# WWII Rate of Turns



## Zipper730 (Jan 14, 2018)

Since there are a couple of polls about what planes were the best dog-fighters, and in those days dog-fighting didn't just mean any close in fight with guns, but specifically fights that involved rapid turning.

I figure there's gotta be some way of organizing all of this data into a single source: I don't claim to know everything about WWII aircraft (I actually know fairly little), but from what I've gathered so far some of the best turning planes would include the following

Ki-43
A6M: Slightly less than the Ki-43

Hurricane: Unsure where it ranks

Spitfire: Slightly less than the Hurricane
There are of course many others, and many variables go into determining a plane's turning performance including the following

Weight: It decreases the responsiveness of the controls, affects maximum g-load at, and raises the corner velocity
The P-51/P-51A could turn inside the P-40 (which could marginally turn inside the Me-109) in typical combat trim; the P-51B/C/D if in a short/medium range layout would also demonstrate favorable performance (but across a wider range of altitudes), but if configured for long-range it was often inferior to the Me-109 except at higher speeds
There were proposals of fitting the Spitfire with slipper tanks and sending them off into combat for greater range: They even factored the performance in with full tanks and slipper-tanks partially emptied against the Me-109, though they ultimately didn't pursue it (probably because the best range required a cruise speed of 240 mph which would be dangerous against the Fw-190)

Altitude: Dictated by stall-speed, though without enough engine power it would mean there'd be inadequate thrust to keep the plane turning, and the slipstream might also be affected by the fact that with less engine power, there'd be less air blown over. The ability to fly at higher mach numbers might help to a point, but I'm not sure about that.

Exterior Stores: Drop-tanks, slipper-tanks, rockets, bombs, etc. All of these add drag in addition to weight.
I'd like to stick to the facts and avoid nationalistic debates and stick to the numbers: In this case, the facts lie in the numbers, so that seems the easiest way to go about it.

Tightest turning circle period
Tightest turning circle under typical speeds, weights & altitudes
Most rapid degree per second rate of turn period
Most rapid turning circle under typical weights, altitudes, speeds
I suppose there were some aircraft that weren't fighters that could turn surprisingly well because they were designed to fly at low speeds and things of that sort. Why not?


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## pbehn (Jan 14, 2018)

first explain the difference between 1 and 3 and then 2 and 4?


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## Zipper730 (Jan 14, 2018)

Technically it's possible to have a tight turning arc that takes awhile if you fly really slow (1 & 3); as for 2 & 4 same applies


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## Ivan1GFP (Jan 15, 2018)

Hello Zipper730,

This is a bit scary to get into yet another discussion about equipment performance, but here goes:
I do not promise to hang around if this starts taking too much time.

I believe you are leaving out a couple really good dogfighting aircraft:
Polikarpov I-153
Fiat CR 32 / CR 42
Gloster Gladiator
Nakajima Ki 43 Hayabusa.

If you look at the table about Lavochkin fighters that was posted in the FW 190 discussion by Tomo Pauk, you can get a few turning times as noted by the Russians. I do not know how accurate they are but they are data points.

I also believe that your ordering of P-40, Me 109G, P-51 is incorrect. I believe the actual order is from best to worst in the order I just listed them. The ordering of the last two is almost certainly correct as tested by the British. In fact in their test, the Me 109G-6/R6 with cannon pods was able to outturn a P-51.
Of course everything varies quite a bit with speed.
The Warbird Buyer's Guide published by Motorbooks International also gave some head to head testing of some of the US fighters. Surprisingly the P-47 and P-51 came out nearly even.

- Ivan.

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## pbehn (Jan 15, 2018)

Zipper730 said:


> Technically it's possible to have a tight turning arc that takes awhile if you fly really slow (1 & 3); as for 2 & 4 same applies


Zipper use your post to inform yourself. Take the argument "ad absurdum". The tightest turning fixed wing aircraft at low speed is the Hawker Harrier because it can do it stood still. At low speeds helicopters are obviously best but no one would dogfight in a helicopter. Turning performance is only significant when planes are of equal or very similar speed. As the speed of the turn increases weight becomes less important while drag becomes more important. While turning performance is of some importance designers and pilots would go for speed every time. The Hurricane may well have been able to beat a Bf109 in instantaneous turn but the top speed difference of circa 30MPH meant the Bf109 could break off contact and there was nothing the Hurricane pilot could do. At the other end of the "ad absurdum" scale the FW190 could out manoeuvre the Mosquito at all speeds except maximum. In a shallow dive at high speed and high altitude the Mosquito still had a little control authority while the FW had almost none. That doesn't mean you choose the Mosquito as your favoured mount though because the situation is completely specific and relies on the FW running out of fuel before you hit the ground.

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## swampyankee (Jan 15, 2018)

One can define several types of "tight turns":

Maximum instantaneous turn rate. 

Maximum sustained turn rate
Minimum sustained turn radius
Minimum instantaneous turn radius
2 and 3 are dependent on power, wing loading, aspect ratio, and aircraft drag. 1 and 4 are essentially dependent on wing loading and maximum instantaneous lift coefficient. In general, they're not the same.


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## swampyankee (Jan 15, 2018)

pbehn said:


> Zipper use your post to inform yourself. Take the argument "ad absurdum". The tightest turning fixed wing aircraft at low speed is the Hawker Harrier because it can do it stood still. *At low speeds helicopters are obviously best but no one would dogfight in a helicopter.* Turning performance is only significant when planes are of equal or very similar speed. As the speed of the turn increases weight becomes less important while drag becomes more important. While turning performance is of some importance designers and pilots would go for speed every time. The Hurricane may well have been able to beat a Bf109 in instantaneous turn but the top speed difference of circa 30MPH meant the Bf109 could break off contact and there was nothing the Hurricane pilot could do. At the other end of the "ad absurdum" scale the FW190 could out manoeuvre the Mosquito at all speeds except maximum. In a shallow dive at high speed and high altitude the Mosquito still had a little control authority while the FW had almost none. That doesn't mean you choose the Mosquito as your favoured mount though because the situation is completely specific and relies on the FW running out of fuel before you hit the ground.




Actually...when I worked at Sikorsky, people were spending a lot of time and money simulating air combat between fixed wing aircraft and helicopters. Basic finding was the fixed wing aircraft didn't stand a chance.


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## Zipper730 (Jan 15, 2018)

Ivan1GFP said:


> I believe you are leaving out a couple really good dogfighting aircraft


I'm sure I did... my knowledge of aircraft is limited even in the post-war era: I'm fine with people adding more information.


> Polikarpov I-153
> Fiat CR 32/ CR 42
> Gloster Gladiator
> Nakajima Ki 43 Hayabusa


I actually meant Ki-43, but wrote Ki-27 by accident... the other designs are all valid as long as they served in the war.


> If you look at the table about Lavochkin fighters that was posted in the FW 190 discussion by Tomo Pauk, you can get a few turning times as noted by the Russians. I do not know how accurate they are but they are data points.


What I got so far would be the following times for a 360 degree turn...

LaGG-3: 18-19 seconds

Yak-1: 17-19 seconds
Yak-7B: 18-19 seconds
Me-109F-4: 19.6 - 20.5 seconds
La-5: 19 seconds
Yak-9: 17-18 seconds
Me-109G-2: 20-21.5
Fw-190A-4: 22-23
Average degree per second rates would come out to the following

LaGG-3: 18.95 - 20.00
Yak-1: 18.95 - 20.18
Yak-7B: 18.95 - 20.00
Me-109F-4: 17.56 - 18.37
Yak-9: 20.00 - 21.18
Me-109G-2: 16.74 - 18.00

Fw-190A-4: 15.65 - 16.59



> I also believe that your ordering of P-40, Me 109G, P-51 is incorrect. I believe the actual order is from best to worst in the order I just listed them. The ordering of the last two is almost certainly correct as tested by the British. In fact in their test, the Me 109G-6/R6 with cannon pods was able to outturn a P-51.
> Of course everything varies quite a bit with speed.


The P-51's figures varies a lot owing to a lot of things.

Long Range Escort Mission: Involves full wing-tanks, center-tank filled, and drop-tanks; by combat the center-tank is usually empty, but the wing tanks are filled
With Drop Tanks: Starts out with the wing & drop-tanks filled; tanks come off when exhausted, or when combat starts: This means the wing tanks are either fully loaded or fairly full.
Internal Fuel: The fuel would be drained down by combat so it would be the lightest



> The Warbird Buyer's Guide published by Motorbooks International also gave some head to head testing of some of the US fighters. Surprisingly the P-47 and P-51 came out nearly even.


That strikes me as a surprise as the P-47 didn't turn very well...



pbehn said:


> Zipper use your post to inform yourself. Take the argument "ad absurdum". The tightest turning fixed wing aircraft at low speed is the Hawker Harrier because it can do it stood still.


Yeah, I suppose that can be taken to the point of absurdity: I could stand still jump and do a 360 in the air... some forward velocity is needed 


> The Hurricane may well have been able to beat a Bf109 in instantaneous turn but the top speed difference of circa 30MPH meant the Bf109 could break off contact and there was nothing the Hurricane pilot could do.


I figure it'd be best to start out with basic data and built up from there...



swampyankee said:


> One can define several types of "tight turns":
> 
> Maximum instantaneous turn rate.
> 
> ...



That's the general rule, I put degrees per second in there because it seemed to have a validity of it's own -- of course it runs into limits (a person doing a jump will spinning -- there 360 degrees a second  ) without a forward speed.



> 2 and 3 are dependent on power, wing loading, aspect ratio, and aircraft drag.


Of course


> 1 and 4 are essentially dependent on wing loading and maximum instantaneous lift coefficient. In general, they're not the same.


I figured aspect-ratio would matter too


> Actually...when I worked at Sikorsky, people were spending a lot of time and money simulating air combat between fixed wing aircraft and helicopters. Basic finding was the fixed wing aircraft didn't stand a chance.


Would that be borne out in fact? I figure a fighter would just have to buzz the plane and knock it out of control.


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## Ivan1GFP (Jan 15, 2018)

Hello Swampyankee,

I would have figured that with a modern jet fighter carrying Air to Air missiles, it would be no contest.
If it were a guns only match up, then the helicopter has a very difficult tracking shot while the jet essentially has an almost stationary and large target and typically has a lot more gun power if not firing rate.
I will also admit that I have no real knowledge in this area.

Hello Zipper730,

If one is looking at instantaneous rates of turn, then above a certain speed, the G tolerance of the pilot is the limiting factor regardless of the aeroplane.
Instantaneous minimum radius would be whatever resulted from that instantaneous G load and airspeed.
Sustained turn would be with whatever energy bleed could be replenished by the propulsion system of the aeroplane.
Energy bleed would tend to vary with a LOT of factors and would be the hardest to get correct.

This of course neglects the fact that for a horizontal turn, the aircraft must be rolled into a bank before the turn.
This data is also not easy to come by and tends to vary a LOT with airspeed.

I know that at least one of the members does a lot of calculations and graphs for this kind of data though I don't really understand how he puts them together so fast.

By the way, although I suggested the data source for some of the Russian aircraft, I believe some of that data is suspect.
Their information for German aircraft has always seemed unreliable to me.

- Ivan.


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## swampyankee (Jan 16, 2018)

Zipper730 said:


> I'm sure I did... my knowledge of aircraft is limited even in the post-war era: I'm fine with people adding more information.
> I actually meant Ki-43, but wrote Ki-27 by accident... the other designs are all valid as long as they served in the war.
> What I got so far would be the following times for a 360 degree turn...
> 
> ...



Regarding helicopters, I don’t know how valid the assumptions were, but most military helicopters aren’t that small, and a fighter pilot relying on high-speed maneuvers at about ground level may find their aircraft fodded by tree limbs. The finding was the helicopter could always get a lock with a missile.


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## Zipper730 (Jan 16, 2018)

Ivan1GFP said:


> If one is looking at instantaneous rates of turn, then above a certain speed, the G tolerance of the pilot is the limiting factor regardless of the aeroplane.


Or the structural limit depending on the aircraft.


> Instantaneous minimum radius would be whatever resulted from that instantaneous G load and airspeed.


Rate of turn and airspeed produces the g-load at that moment in time.


> Energy bleed would tend to vary with a LOT of factors and would be the hardest to get correct.


Well yeah, thrust varies with so many things: Air-temperature, air-pressure, air-density, and out of that mach number, indicated airspeed, and true airspeed.

Indicated airspeed by itself isn't entirely a valid parameter: Really, mach number is, because that dictates how the airflow goes over the wing at different AoA

Critical AoA is higher when subsonic, once shock-wave formation starts, it produces airflow disturbances that make stalls easier.

I'm not sure how Critical AoA changes when supersonic, but L/D ratios drop supersonic for the same airspeed: Seems to be the result of shock-wave formation, increased turbulent airflow, and shifting of the center of pressure.



> This of course neglects the fact that for a horizontal turn, the aircraft must be rolled into a bank before the turn.


That's right, so the higher the g-load, the higher the bank. You want a fast roll rate to get the most out of the turn, there's actually a term for that modern day -- Torsional agility.


> This data is also not easy to come by and tends to vary a LOT with airspeed.
> 
> I know that at least one of the members does a lot of calculations and graphs for this kind of data though I don't really understand how he puts them together so fast.


Well, if you can get him over here, that'd be real useful 


> By the way, although I suggested the data source for some of the Russian aircraft, I believe some of that data is suspect. Their information for German aircraft has always seemed unreliable to me.


So their data is accurate?




swampyankee said:


> Regarding helicopters, I don’t know how valid the assumptions were, but most military helicopters aren’t that small, and a fighter pilot relying on high-speed maneuvers at about ground level may find their aircraft fodded by tree limbs. The finding was the helicopter could always get a lock with a missile.


I would have figured they could have been struck with a missile from a plane with a PD radar? Regardless, their slow speed permits a tight turn-rate, but that is ultimately limited by blast radius from the weapon fired.


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## DarrenW (Jan 16, 2018)

Excellent thread and a topic well worthy of discussion.

Another factor to consider is whether or not the pilot is wearing some type of anti-gravity suit. The US Navy began issuing them to their pilots during the latter stages of WWII (initially referred to as the "Z" suit) and had great success with them. These of course would allow a pilot to push the turn closer to the aircraft's limit, more so than what could be accomplished otherwise. Figures obtained with it's use would definitely skew the numbers a bit.

Just my two-cents on the subject. Good luck with your quest!


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## Shortround6 (Jan 16, 2018)

This is my favorite graph on this subject.
http://www.spitfireperformance.com/spit109turn.gif

Please note the variations in turning times, speeds, diameters. also note the line marked "angle of straight climb" as it pretty well defines the ability to turn without losing altitude. It pretty much explains why turning fights rapidly descended in altitude.

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## pbehn (Jan 16, 2018)

DarrenW said:


> Excellent thread and a topic well worthy of discussion.
> 
> Another factor to consider is whether or not the pilot is wearing some type of anti-gravity suit. The US Navy began issuing them to their pilots during the latter stages of WWII (initially referred to as the "Z" suit) and had great success with them. These of course would allow a pilot to push the turn closer to the aircraft's limit, more so than what could be accomplished otherwise. Figures obtained with it's use would definitely skew the numbers a bit.
> 
> Just my two-cents on the subject. Good luck with your quest!


Before G suits the seating position was important, I believe the seating in a BF 109 is a bit strange because the knees must be raised to fly. Some aircraft had two feet positions on the feet controls, one low for cruising the other raised for combat. The British experimented with leg amputations and this appeared to be successful with Douglas Bader but met with much opposition among young pilots.

Edit:- posted in jest but I suspect the effect of high G turns on amputated leg stumps operating flight controls must have been agony. RIP Sir Douglas.

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## Ivan1GFP (Jan 16, 2018)

Zipper730 said:


> Or the structural limit depending on the aircraft.



In general this is not true if the discussion is limited to WW2 era fighters and pilots without G suits.
There were a few aircraft (Think Ki 43-I) that were very very flimsy, but most could stand more G than a pilot could without blacking out.
I figure a pilot is pretty much done by around 8G and maybe before that while most fighters are stressed to withstand around 12G before structural failure. The problem is that this is in initial designs and with the added weight during production, that limit gets lower.
Also, the REAL intended load limit is around 8G, so past that there may be some permanent structural damage even though there is no catastrophic failure.



Zipper730 said:


> Well yeah, thrust varies with so many things: Air-temperature, air-pressure, air-density, and out of that mach number, indicated airspeed, and true airspeed.



In general, this is not quite as difficult to calculate as you are describing. Air Density, Propeller Advance Ratio, RPM, and Mach effects and of course exhaust thrust makes for a pretty good approximation.



Zipper730 said:


> Indicated airspeed by itself isn't entirely a valid parameter: Really, mach number is, because that dictates how the airflow goes over the wing at different AoA
> 
> Critical AoA is higher when subsonic, once shock-wave formation starts, it produces airflow disturbances that make stalls easier.
> 
> ...



If your discussion is intended to go toward modern jet and other supersonic aircraft, I really have nothing to contribute to this discussion.
That is not my area of interest and I have no data or tools to support any analysis there.

- Ivan.


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## windswords (Jan 18, 2018)

Interesting topic, although I don't know if you can create any kind of "definitive" list as there are so many variables (weight, altitude, model etc.). I will say this: turning radius while important, is the most over rated of attributes in air to air combat; roll rate is the most under rated. All in my opinion of course. 

Wind Swords

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## Zipper730 (Jan 18, 2018)

DarrenW said:


> Excellent thread and a topic well worthy of discussion.


Thanks


> Another factor to consider is whether or not the pilot is wearing some type of anti-gravity suit. The US Navy began issuing them to their pilots during the latter stages of WWII (initially referred to as the "Z" suit) and had great success with them.


I didn't know the USN was the first to use them...



pbehn said:


> Before G suits the seating position was important, I believe the seating in a BF 109 is a bit strange because the knees must be raised to fly. Some aircraft had two feet positions on the feet controls, one low for cruising the other raised for combat.


That makes sense, the F-16 had the pilot's feet raised as well: It makes it hard to pool blood in the legs and feet. I'm not sure what it does with negative g-loads, but...


> The British experimented with leg amputations and this appeared to be successful with Douglas Bader but met with much opposition among young pilots.


Well, if an amputee can fly, I see little problem with it: I'm not really fond of hacking off the legs of perfectly healthy pilots (seems rather brutal, plus I think it would probably be counterproductive).


> I suspect the effect of high G turns on amputated leg stumps operating flight controls must have been agony.


The blood-flow, or the pressure of the stump against the proesthetic?



Ivan1GFP said:


> In general this is not true if the discussion is limited to WW2 era fighters and pilots without G suits.


That is a good point. I'm not sure what the Ki-43 was rated for, but typical planes in the USAAF/USN seemed rated often for 7.3g to 8g normal.


> Also, the REAL intended load limit is around 8G, so past that there may be some permanent structural damage even though there is no catastrophic failure.


And each time it'd get weaker and weaker...


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## fubar57 (Jan 18, 2018)

Zipper730 said:


> Thanks I didn't know the USN was the first to use them...



The FAA first used the G-Suit operationally in 1942

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## Zipper730 (Jan 18, 2018)

Shortround6 said:


> This is my favorite graph on this subject.
> http://www.spitfireperformance.com/spit109turn.gif
> 
> Please note the variations in turning times, speeds, diameters. also note the line marked "angle of straight climb" as it pretty well defines the ability to turn without losing altitude.


I was really scratching my head with that one! If I read that correct if equal to or below that line, you could hold a level turn? 

Also, regarding true airspeed and corrected airspeed, which is accurate? I assume corrected...



IvanGFP said:


> In general, this is not quite as difficult to calculate as you are describing. Air Density, Propeller Advance Ratio, RPM, and Mach effects and of course exhaust thrust makes for a pretty good approximation.


When you say propeller advance ratio, you mean pitch right? Regardless, normally I would be inclined to say "engine power only affects sustained agility", but with propellers, the slipstream does augment lift itself, so that is actually important. 

Mach effects don't just affect the wing and tail surfaces, but the propeller too, the same for exhaust thrust (ram compression).



windswords said:


> Interesting topic, although I don't know if you can create any kind of "definitive" list as there are so many variables (weight, altitude, model etc.). I will say this: turning radius while important, is the most over rated of attributes in air to air combat; roll rate is the most under rated. All in my opinion of course.


Roll rate is highly important actually...


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## Glider (Jan 18, 2018)

windswords said:


> Interesting topic, although I don't know if you can create any kind of "definitive" list as there are so many variables (weight, altitude, model etc.). I will say this: turning radius while important, is the most over rated of attributes in air to air combat; roll rate is the most under rated. All in my opinion of course.
> 
> Wind Swords


Again I have to agree. To take a silly but real example, I would defy any aircraft to stay with a glider in a tight turn, but the fact that my roll rate is probably more akin to a 747 would tend to be problem in the real world


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## swampyankee (Jan 19, 2018)

Zipper730 said:


> I was really scratching my head with that one! If I read that correct if equal to or below that line, you could hold a level turn?
> 
> Also, regarding true airspeed and corrected airspeed, which is accurate? I assume corrected...
> 
> ...



Advance ratio is airspeed (ft or meters per second) divided by (diameter (ft pr meters) times rate of rotation(rev/sec); pitch is chosen from advance ratio. For more about prop parameters, see 11.7 Performance of Propellers

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## Barrett (Jan 19, 2018)

Ref. the 109 v. the Hurricane. The Hurrybox certainly could out-turn the 109 (we tend to say THE Hurricane and THE 109 when of course there were model variations) but in any case the RAFish chap probably was purely defensive. 

However, FWIW: the 109 pilots I knew said that an Emil/etc could stay with a Spit at typical altitudes/airspeeds if the 109 driver was willing to fight in buffet with the lats extended. Same applied to many Soviet fighters. I'm writing a detailed Topgun book with the school's founder, and he describes how (in specific circumstances) the F-4 could turn with other "fighterjets" if the Phantom pilot had trained to fight in deep buffet. McDonnell Douglas was appalled at first, then really impressed. Of course, the Phantom's main advantage was its vertical performance to negate a tighter-turning adversary.

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## pbehn (Jan 19, 2018)

Barrett said:


> However, FWIW: the 109 pilots I knew said that an Emil/etc could stay with a Spit at typical altitudes/airspeeds if the 109 driver was willing to fight in buffet with the lats extended..


From what I read, with the top Bf 109 pilots the "fun" didn't start until the slats extended. It was then just a question of skill and nerve.


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## Glider (Jan 19, 2018)

pbehn said:


> From what I read, with the top Bf 109 pilots the "fun" didn't start until the slats extended. It was then just a question of skill and nerve.


Unfortunately if you do that you will have lost all your energy and speed and would be a sitting duck if there are other enemy aircraft nearby


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## pbehn (Jan 19, 2018)

Glider said:


> Unfortunately if you do that you will have lost all your energy and speed and would be a sitting duck if there are other enemy aircraft nearby


It is way above my pay grade on aerodynamics but I was under the impression that the deployment was dependent on the wings angle of attack, in a combat situation no more or less dangerous than for an opposing Spitfire for example as the speeds were about the same.


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## Snowygrouch (Jan 19, 2018)

Shortround6 said:


> This is my favorite graph on this subject.
> http://www.spitfireperformance.com/spit109turn.gif
> 
> Please note the variations in turning times, speeds, diameters. also note the line marked "angle of straight climb" as it pretty well defines the ability to turn without losing altitude. It pretty much explains why turning fights rapidly descended in altitude.



Not to be a party pooper - but I do not like websites that post odd pages of reports. Because you miss important things - I have photographed that entire original report, and I can tell you that all those graphs were constructed by a theoretical formula used to try to predict the turning performance at various speeds/altitudes because its basically impossible to actually conduct enough trials objectively to make a real data-table. Hence, sadly those charts are nothing but a mathematical contstruct.

This does not mean the results they project are totally wrong, but I think its very important to realise that they are theoretical projections based on an unsubstantiated set of equations someone was messing about with at that time - and are NOT - repeat..NOT test data. I quote from the real report below that I copied myself:

"In a recent report on the dog-fight Gates gives an analysis whereby the performance on an aeroplane in steady spiral flight at full throttle can be estimated from its measured full throttle performance in straight flight (partial climbs and top speed); the analysis leads to a compact diagram from which the radius and time of turn, and the corresponding rate of ascent or descent can be obtained at any given airspeed and normal "g", such diagrams have been constructed for the Spitfire and Me109, and are given in Fig 17 together with an explanation of their use"

(Figure 17 is the chart you posted)

Personally I regard the whole report as....well... I`ll give you another quote and leave it for you to decide.

"The tests have shown that as a fighter the Me109 is in general inferior to the Hurricane or Spitfire"

Possibly my favourite quote from any WW2 performance comparison report follows - which basically translates as "the Spitfire turns much tighter except when it doesnt". My view is that its almost impossible to compare combat aircraft of any kind unless the difference between them is almost a generation.

"The Me.109 pilot suceeded in keeping on the tail of the Spitfire in many cases, despite the latter aeroplane`s superior turning performance, because a number of the Spitfire pilots failed to tightern up the turn sufficiently." (page 32)

Incidentally if anyone wants to go read this themselves, they can do by going to Kew in London and asking for "AVIA-6-8714"

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## Shortround6 (Jan 19, 2018)

I don't particularly care if the chart isn't 100% accurate. I knew that it was a mathematical construct. 
However it points out the absurdity of trying to pick one "test" such as the time to turn a 360 degree circle (especially with both speed and radius/diameter unspecified) and use it to decide which plane turned better. Or to try to come up with a "simple" equation/formula based on wing loading or some other basic parameter. 
I would also note that the chart is figured for 12,000ft and that the ability to _sustain _a turn is tied to the surplus/excess power available.
Different wings are going to have different "lift" at different altitudes affecting the turning circles and since the surplus/excess also varies (by a greater amount) with altitude sustained turns are going vary considerably with altitude. 
They are also going to vary considerably between different models of the same aircraft if the engines vary in power by much.

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## pbehn (Jan 19, 2018)

Shortround6 said:


> I don't particularly care if the chart isn't 100% accurate. I knew that it was a mathematical construct.
> However it points out the absurdity of trying to pick one "test" such as the time to turn a 360 degree circle (especially with both speed and radius/diameter unspecified) and use it to decide which plane turned better. Or to try to come up with a "simple" equation/formula based on wing loading or some other basic parameter.
> I would also note that the chart is figured for 12,000ft and that the ability to _sustain _a turn is tied to the surplus/excess power available.
> Different wings are going to have different "lift" at different altitudes affecting the turning circles and since the surplus/excess also varies (by a greater amount) with altitude sustained turns are going vary considerably with altitude.
> They are also going to vary considerably between different models of the same aircraft if the engines vary in power by much.


To me the imaginary absurdity, held by many, is that in WW2 there were huge numbers of pilots who engaged in a turning radius combat. and the loser watched the victor closing in over a series of turns and then got shot down. Malans rules of air fighting stated, do not fly straight and level for more than thirty seconds, circling around for a period of minutes is even worse.


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## Greyman (Jan 19, 2018)

Snowygrouch said:


> Personally I regard the whole report as....well... I`ll give you another quote and leave it for you to decide.
> 
> "The tests have shown that as a fighter the Me109 is in general inferior to the Hurricane or Spitfire"



I would say the report is fantastic, and the RAE's conclusions on the 109's general inferiority are sound - _based on their criteria_ - where overall dogfighting ability appears paramount.


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## Zipper730 (Jan 22, 2018)

swampyankee said:


> Advance ratio is airspeed (ft or meters per second) divided by (diameter (ft pr meters) times rate of rotation(rev/sec); pitch is chosen from advance ratio. For more about prop parameters, see 11.7 Performance of Propellers


I'll take a look if I get the chance (I'm starting another criminal justice course -- I should major in this).



Barrett said:


> I'm writing a detailed Topgun book with the school's founder, and he describes how (in specific circumstances) the F-4 could turn with other "fighterjets" if the Phantom pilot had trained to fight in deep buffet.


Actually at the corner velocity, the plane could sustain around 7g, which would put it above the sustained turn rate of the MiG-21. The problem was the corner velocity was like 420 knots, and the MiG-21's was in the 300-knot range. The F-102's were about the same, the F-106 was probably somewhat higher (10-15 knots) because it had a heavier air-frame on a similar wing (the early F-102's has a wing of 661 square feet, later on 695; the F-106A's first had a 695 square foot wing, enlarged to 697) but with a cleaner frame, better inlets it'd probably have better sustained performance.

With slatted F-4E's, you would have a turning advantage even at lower speeds that would stay with the MiG-21's and equal or beat the F-106 at some altitudes, though once you got above 31,000-32,000 feet, the F-106 could stay with them or exceed their turn



pbehn said:


> It is way above my pay grade on aerodynamics but I was under the impression that the deployment was dependent on the wings angle of attack, in a combat situation no more or less dangerous than for an opposing Spitfire for example as the speeds were about the same.


Well, technically it was a function of dynamic pressure and g-load


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## FLYBOYJ (Jan 22, 2018)

Zipper730 said:


> The F-4 required some skill to fly it, due to a combination of heavy adverse yaw and a highly swept wing, you'd be using fairly firm rudder inputs with aileron under some case, and at higher alpha, you'd just be using the rudder and centering the stick, pulling back as needed to hold the g-load.


And where are you getting your reference for this? I've flown in an F-4, did some aerobatics and found you needed very little rudder at lower speeds. At high speeds you didn't touch the rudder

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## Zipper730 (Jan 22, 2018)

FLYBOYJ said:


> And where are you getting your reference for this?


There was a book entitled "Clashes", but also this 
_View: https://www.youtube.com/watch?v=Y6RcTtGfG3E_
which seem to have similarities in descriptions.


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## Greyman (Jan 22, 2018)

Zipper730 said:


> I've wondered why that happened: There were some guesses about that, as well as some personal speculation.



_5.1 Dog fights with Spitfire and Hurricane .

...

When the Me.109 was following the Hurricane or Spitfire, it was found that our aircraft turned inside the Me.109 without difficulty when flown by determined pilots who were not afraid to pull their aeroplanes round hard in a tight turn. In a surprisingly large number of cases, however, the Me.109 succeeded in keeping on the tail of the Spitfire or Hurricane during these turning tests, merely because our pilots would not tighten up the turn sufficiently from fear of stalling and spinning.

...

5.4 Discussion .

...

As mentioned in 5.1., the Me.109 pilot succeeded in keeping on the tail of the Spitfire in many cases, despite the latter aeroplane's superior turning performance, because a number of the Spitfire pilots failed to tighten up the turn sufficiently. If the stick is pulled back too far on the Spitfire in a tight turn, the aeroplane may stall rather violently, flick over on to its back, and spin. Knowledge of this undoubtedly deters the pilot, particularly if he is not very experienced, from tightening his turn when being chased._

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## FLYBOYJ (Jan 22, 2018)

Zipper730 said:


> There was a book entitled "Clashes", but also this
> _View: https://www.youtube.com/watch?v=Y6RcTtGfG3E_
> which seem to have similarities in descriptions.



I could tell you that's very generic and probably the same on about dozen combat aircraft of the period. You could actually roll an F-4 with the rudder only (the aircraft shakes and buffets while this is going on). I would disagree that the F-4 "required some skill to fly it." Like any combat aircraft of the day, "training enables capability." Don't buy into many of those 1960's training clips, they could be a little over-dramatic.

It is a cool clip though!


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## Shortround6 (Jan 22, 2018)

Zipper730 said:


> I've wondered why that happened: There were some guesses about that, as well as some personal speculation.
> 
> The Me-109's slats acted as a stall-warning device, which the Spitfire did not have: This allowed them to better gauge when they were getting close to stalling
> The Spitfire seemed to indicate a tendency for being potential twitchy on the controls (neutral stability), so some pilots might have feared snapping the wings off



Please remember that there were no anti-suits, and no "G" meters in the cockpit. Pulling 5-6 "G"s means you are near blacking out (or at least greying out) and your arms are 5-6 times heavier than normal while trying to control the stick. Nobody pulled a perfect 5 "G" turn. There was constant adjustment of the elevators to control the turn and the actual "G"s could fluctuate considerably from one second to the next even in a 10 second 180 degree turn. 

I don't think anybody really worried about snapping wings off, this wasn't WW I. What they worried about was stalling the plane while turning at over a 70 degree bank and snapping into an inverted spin. Usually fatal if done at low altitude. 
Low time pilots in just about all WW II fighters rarely pushed the aircraft to the aircraft's limits (official).


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## pbehn (Jan 22, 2018)

Greyman said:


> _5.1 Dog fights with Spitfire and Hurricane .
> 
> ...
> 
> ...


All I read from this is that experienced pilots do better than inexperienced ones, which is well known.

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## pbehn (Jan 22, 2018)

Zipper730 said:


> Well, technically it was airspeed and g-load...
> 
> I've wondered why that happened: There were some guesses about that, as well as some personal speculation.
> 
> ...


Please explain how the g load deployed the leading edge slats? I believe it is the angle of attack of the wing because I read it here. (My bold) Leading-edge slat - Wikipedia

Slats were first developed by Gustav Lachmann in 1918. A crash in August 1917, with a Rumpler C aeroplane on account of stalling caused the idea to be put in a concrete form, and a small wooden model was built in 1917 in Cologne. In 1918, Lachmann presented a patent for leading-edge slats in Germany. However, the German patent office at first rejected it as the office did not believe in the possibility of increasing lift by dividing the wing.[4][5]

Independently of Lachmann, Handley Page Ltd in Great Britain also developed the slotted wing as a way to postpone stall by reducing the turbulence over the wing at high angles of attack, and applied for a patent in 1919; to avoid a patent challenge, they reached an ownership agreement with Lachmann. That year a De Havilland D.H.9 was fitted with slats and flown.[6] Later, a D.H.4 was modified as a monoplane with a large wing fitted with full span leading edge and back ailerons (i.e. what would later be called flaps) that could be deployed in conjunction with the leading-edge slats to test improved low speed performance.[7] Several years later, having subsequently taken employment at the Handley-Page aircraft company, Lachmann was responsible for a number of aircraft designs, including the Handley Page Hampden.

Licensing the design became one of the company's major sources of income in the 1920s. The original designs were in the form of a fixed slot in the front of the wing, a design that was found on a number of STOL aircraft.

During World War II, German aircraft commonly fitted a more advanced version that pushed back flush against the wing by air pressure to reduce drag, *popping out when the angle of attack increased during slower flight*. Notable slats of that time belonged to the German Fieseler Fi 156 _Storch_. These were similar in design to retractable slats, but were fixed non-retractable slots. The slotted wing allowed this aircraft to take off into a light wind in less than 45 m (150 ft), and land in 18 m (60 ft). Aircraft designed by the Messerschmitt company employed automatic, spring-loaded leading-edge slats as a general rule, except for the Alexander Lippisch-designed Messerschmitt Me 163B _Komet_ rocket fighter, which used fixed slots built integrally with, and just behind the wing panel's outer leading edges instead.

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## pbehn (Jan 22, 2018)

Zipper730 said:


> The Me-109's slats acted as a stall-warning device, which the Spitfire did not have: This allowed them to better gauge when they were getting close to stalling
> The Spitfire seemed to indicate a tendency for being potential twitchy on the controls (neutral stability), so some pilots might have feared snapping the wings off


The slats did not act as a stall warning device with expert pilots because they continued to push in a turning combat after they deployed. The Spitfire had the same stall warning as most aircraft of the period, that is buffeting on the wings caused by the washout. In this respect the Spitfire was better than most. As previously, many pilots were in combat during the BoB with just 50 hours on type whereas 200 hrs is actually needed. With the extra 150 hrs pilots become familiar with stall performance and stall recovery. Did any Spitfire actually snap its wings off, ever, while turning?

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## swampyankee (Jan 22, 2018)

The slats weren't stall warning devices; they were stall _preventing_ devices. Also, the Tiger Moth, produced before WW2, had automatic leading edge slats. Like a lot of aero things, people talked.

Tapered wings, unless there is enough washout, will stall from the tips first, as tapered wings have greater lift coefficients towards the tips. This is bad, as that's where one puts the ailerons _and_ the separated flow from the stalled wing won't hit anything, so there's no buffeting, _i.e._, no warning. In an aircraft like the Bf109, which was built with little washout in the wing, the tips would stall first, leading to loss of lateral control (this may lead to a problem known as "crashing," as it's likeliest to happen near the ground, on approach). By putting on the automatic slats, the tips don't stall, so lateral control can be maintained even after the wing is stalled at the root.

The Spitfire, by the way, had washout and an elliptical wing; it's wing may have stalled from the root out, which is what you want. The most extreme aircraft design to prevent tip stall was the XF-91, proof that US designers may not have been teetotallers.

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## Zipper730 (Jan 22, 2018)

Greyman said:


> _When the Me.109 was following the Hurricane or Spitfire, it was found that our aircraft turned inside the Me.109 without difficulty when flown by determined pilots who were not afraid to pull their aeroplanes round hard in a tight turn. In a surprisingly large number of cases, however, the Me.109 succeeded in keeping on the tail of the Spitfire or Hurricane during these turning tests, merely because our pilots would not tighten up the turn sufficiently from fear of stalling and spinning. . .If the stick is pulled back too far on the Spitfire in a tight turn, the aeroplane may stall rather violently, flick over on to its back, and spin._


So the issue was the fear over being able to properly gauge when they'd stall?



Shortround6 said:


> Please remember that there were no anti-suits, and no "G" meters in the cockpit. Pulling 5-6 "G"s means you are near blacking out (or at least greying out) and your arms are 5-6 times heavier than normal while trying to control the stick. Nobody pulled a perfect 5 "G" turn. There was constant adjustment of the elevators to control the turn and the actual "G"s could fluctuate considerably from one second to the next even in a 10 second 180 degree turn.


That makes sense, different amount of stick forces are needed to pull a given g-load at a given speed.


> What they worried about was stalling the plane while turning at over a 70 degree bank and snapping into an inverted spin.


Would that flood the engine?


> Low time pilots in just about all WW II fighters rarely pushed the aircraft to the aircraft's limits


Makes enough sense: They don't know what they can and cannot get away with... there's natural skill in that, but also practice is often a helpful cure.



pbehn said:


> Please explain how the g load deployed the leading edge slats?


Automatic slats were extended through usually two means: Dynamic pressure and G-load

Slats extend outwards and downwards opening up an aerodynamic gap between the slat and the leading edge, which increases lift and delays stall-onset

G-load is correlated to lift, and lift is related to angle of attack and airspeed
As angle of attack increases, g-load increases until a stall occurs; at low speeds, the amount of lift available ranges from being able to maneuver only to a minimum extent, to actually stalling at the point at which you are holding 1g (stall speed).
The extension of the slats as a function of dynamic pressure ensures that when lift is very low, the slats will come out and increase it.

The extension of the slats as a function of g-load ensures that they come out when angle of attack is high



> The slats did not act as a stall warning device with expert pilots because they continued to push in a turning combat after they deployed.


It would provide a guide as to how close you were getting...


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## Zipper730 (Jan 22, 2018)

FLYBOYJ said:


> Don't buy into many of those 1960's training clips, they could be a little over-dramatic.


I found the video interesting because it matched a statement made by the author of Clashes who was an RF-4 pilot, but clarified things a little better.

It does seem to confirm what Barrett said about having to fight in deep buffet


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## pbehn (Jan 23, 2018)

Zipper730 said:


> So the issue was the fear over being able to properly gauge when they'd stall?
> 
> That makes sense, different amount of stick forces are needed to pull a given g-load at a given speed.
> Would that flood the engine?
> ...



so we agree on angle of attack then?

The slats normal position is "out" or deployed, it is solely air pressure that compresses the springs. In level flight the slats will be pushed back to the wing at a certain speed.


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## DarrenW (Jan 23, 2018)

Shortround6 said:


> Please remember that there were no anti-suits, and no "G" meters in the cockpit. Pulling 5-6 "G"s means you are near blacking out (or at least greying out) and your arms are 5-6 times heavier than normal while trying to control the stick...



And once pilots began utilizing G suits the game changed dramatically. I have a US combat report from 1945 which basically states that the accelerometers installed on the aircraft were registering as high as 8 Gs but the pilots were not affected by it much.

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## Zipper730 (Jan 23, 2018)

pbehn said:


> so we agree on angle of attack then?


Indirectly as I explained: Though I guess the goal is that it extends at low speed where AoA is higher.



DarrenW said:


> And once pilots began utilizing G suits the game changed dramatically. I have a US combat report from 1945 which basically states that the accelerometers installed on the aircraft were registering as high as 8 Gs but the pilots were not affected by it much.


That's quite good


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## FLYBOYJ (Feb 2, 2018)

Zipper730 said:


> I found the video interesting because it matched a statement made by the author of Clashes who was an RF-4 pilot, but clarified things a little better.
> 
> It does seem to confirm what Barrett said about having to fight in deep buffet


Well having actually flown in F-4s, i still find some of the comments in the movie a little over dramatic, but then again it was a training film made 50 years ago.

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## Zipper730 (Feb 2, 2018)

FLYBOYJ said:


> Well having actually flown in F-4s


What model if I may ask?


> i still find some of the comments in the movie a little over dramatic


Well I think they were to iron home the point of flying the plane right as if you got into a flat spin you were doomed.

Frankly, the USAF at the time was far too obsessed with safety to emphasize the aggressive combat training needed to endure in combat. I'm not saying I don't think safety is important -- I just think it has to be balanced against the danger of the war you're fighting. War is inherently dangerous.

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## pbehn (Feb 2, 2018)

Zipper730 said:


> What model if I may ask?
> Well I think they were to iron home the point of flying the plane right as if you got into a flat spin you were doomed.
> 
> Frankly, the USAF at the time was far too obsessed with safety to emphasize the aggressive combat training needed to endure in combat. I'm not saying I don't think safety is important -- I just think it has to be balanced against the danger of the war you're fighting. War is inherently dangerous.


Do you have any proof at all for this? Fighting is inherently dangerous but I can put forward a very good argument that proves the top aces in two world wars were cowards, "if it is a fair fight you have done something wrong", they were as much, if not more concerned with their own survival as they were with a "kill". If the USAF is in the position of losing football games by two goals to one they can try to score more or concede less, constructing strategies to concede less is not being "far too obsessed with safety" in fact the strategy worked.


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## Zipper730 (Feb 2, 2018)

pbehn said:


> Do you have any proof at all for this?


There were numerous writings about the USAF during the 1950's and 1960's. If I recall it had to do with several things

The attitude that air superiority wouldn't be essential: For a nuclear conflict, there's probably some truth to that (particularly if the flight profile is (Lo-Lo-Lo); for non-nuclear war, well that wouldn't always apply as you would need more aircraft to do the same job, and a protracted campaign (which brings the amount of "acceptable losses" lower as you need to sustain the campaign) which would probably be measured in weeks to months instead of a day or two, maybe a few days at most.

The fixation on safety seemed to start with SAC, and revolved around early jet aircraft: The USN & USAF both had problems and both implemented solutions, but the USAF seemed to lose their mind; this was then carried over progressively to TAC.



> Fighting is inherently dangerous but I can put forward a very good argument that proves the top aces in two world wars were cowards, "if it is a fair fight you have done something wrong"


Okay, we are thinking of two different forms of safety.

I was talking about robust training being needed if a war breaks out to allow pilots to maximize the use of their aircraft, craft tactics and structure the combat so it is most in their favor. This degree of training often keeps pilots from getting killed because they know when they're getting into a dangerous situation (so they can avoid it), avoid falling into traps that can get them killed if the enemy were to turn the tables on them (so they can avoid such a set-up).


> If the USAF is in the position of losing football games by two goals to one they can try to score more or concede less, constructing strategies to concede less is not being "far too obsessed with safety" in fact the strategy worked.


If you can't score a lot, make sure they can't score on you?


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## pbehn (Feb 2, 2018)

Zipper730 said:


> There were numerous writings about the USAF during the 1950's and 1960's. If I recall it had to do with several things
> 
> The attitude that air superiority wouldn't be essential: For a nuclear conflict, there's probably some truth to that (particularly if the flight profile is (Lo-Lo-Lo); for non-nuclear war, well that wouldn't always apply as you would need more aircraft to do the same job, and a protracted campaign (which brings the amount of "acceptable losses" lower as you need to sustain the campaign) which would probably be measured in weeks to months instead of a day or two, maybe a few days at most.
> 
> ...


I asked for proof not musings, as a British national I have no great knowledge of the USA post war military, but your post was completely dismissive of the actions of people who had many lives in their hands. An "obsession with safety" with early jet aircraft may have stemmed from the number of early jet aircraft that crashed and even as far as the number of people in training who did not eject when they could have.


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## FLYBOYJ (Feb 2, 2018)

Zipper730 said:


> What model if I may ask?
> Well I think they were to iron home the point of flying the plane right as if you got into a flat spin you were doomed.


F-4D, F-4E. We had an RF-4E but I never got to fly in that one


Zipper730 said:


> Frankly, the USAF at the time was far too obsessed with safety to emphasize the aggressive combat training needed to endure in combat. I'm not saying I don't think safety is important -- I just think it has to be balanced against the danger of the war you're fighting. War is inherently dangerous.


 Actually it was the opposite. There were many things being done during that period that were terribly unsafe. There was little room for discussion and safety mitigation because of the pace of the Vietnam War. Look at the accident rates of that period - they were horrendous by today's standards. 
List of aircraft losses of the Vietnam War - Wikipedia

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## FLYBOYJ (Feb 2, 2018)

Zipper730 said:


> The fixation on safety seemed to start with SAC, and revolved around early jet aircraft: The USN & USAF both had problems and both implemented solutions, but the USAF seemed to lose their mind; this was then carried over progressively to TAC.


Zipper, that is one very ignorant statement. Unless you have some hands on experience or can quantify that statement, to put it bluntly, you're talking out of your ass, really! 

The safety card was a necessity and probably more could have and should have been done to spare the lives of many young men who perished during that period just to attempt to see how much the muscle could stretch. Unless you were there, either as a maintainer or pilot, please keep your ill-informed armchair perspectives to a minimum.

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## DerAdlerIstGelandet (Feb 2, 2018)

Fixation on safety? 

I'm confused as to what the problem with that is.


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## Zipper730 (Feb 3, 2018)

DerAdlerIstGelandet said:


> Fixation on safety?
> 
> I'm confused as to what the problem with that is.


When it reaches a point that it undermines effective training...


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## Zipper730 (Feb 3, 2018)

FlyboyJ said:


> Unless you were there, either as a maintainer or pilot, please keep your ill-informed armchair perspectives to a minimum.


Since I don't want to be banned, I'll stop.


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## pbehn (Feb 3, 2018)

Zipper730 said:


> When it reaches a point that it undermines effective training...


From the first world war where planes and pilots were treated as disposable the cost of an aircraft steadily increased, with post war jets the cost went up still further and the pilot is always a more valuable asset than the plane he flies. The B 29 could not suffer the loss rates that were accepted on B17 and B 24s not only because of the huge difference in cost but the similar difference in training for pilots and flight engineers. Disregarding safety was simply not affordable, the object is to down the enemy not yourself.

Anyone with good practical skills can build a plane similar to a ww1 aircraft, any Euromillions lottery winner can buy a ww2 warbird and the training required to fly it, this includes armament, warbirds are not armed but machine guns are not prohibitively expensive. Even a huge winner on a lottery cannot afford to buy and run something like an F4 for more than a couple of years and that is without using any arms which cost millions each.


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## DerAdlerIstGelandet (Feb 3, 2018)

Zipper730 said:


> When it reaches a point that it undermines effective training...



What?

You are talking to an aviation safety and quality assurance advisor...

Nothing in aviation trumps safety.

My experience in aviation is pretty broad. At least I like to believe. Army air crew member, mechanic, private pilot, safety advisor, and in all these years nothing comes before a crew going home at night and an aircraft safe in a hangar.

Why would you put training before the safety of your most important asset? I’m honestly at a loss of words here, and not sure how to dumb this down any more.

And how the hell does safety, get in the way of training? Where are you coming up with this?

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## DerAdlerIstGelandet (Feb 3, 2018)

Maybe I am looking at things from a modern point of view, but I like to think safety was evolving back then as well. Even during a war,

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## FLYBOYJ (Feb 3, 2018)

Zipper730 said:


> Since I don't want to be banned, I'll stop.


 Smart move.


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## FLYBOYJ (Feb 3, 2018)

Zipper730 said:


> When it reaches a point that it undermines effective training...



Do you even know anything about combat training aside what you might have read or seen on youtube? So in your worldly aviation experience, tell us what is effective training?


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## pbehn (Feb 3, 2018)

Below are Adolph Malans rules of air fighting, only the first two have no aspect of self preservation AKA safety.
*
TEN OF MY RULES FOR AIR FIGHTING*


Wait until you see the whites of his eyes. Fire short bursts of one to two seconds only when your sights are definitely "ON".
Whilst shooting think of nothing else, brace the whole of your body: have both hands on the stick: concentrate on your ring sight.
Always keep a sharp lookout. "Keep your finger out".
Height gives you the initiative.
Always turn and face the attack.
Make your decisions promptly. It is better to act quickly even though your tactics are not the best.
Never fly straight and level for more than 30 seconds in the combat area.
When diving to attack always leave a proportion of your formation above to act as a top guard.
_INITIATIVE_, _AGGRESSION_, _AIR DISCIPLINE_, and _TEAMWORK_ are words that MEAN something in Air Fighting.
Go in quickly - Punch hard - Get out!


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## Greyman (Feb 3, 2018)

FLYBOYJ said:


> Do you even know anything about combat training aside what you might have read or seen on youtube? So in your worldly aviation experience, tell us what is effective training?



I've listened to an F-16 pilot complain about the altitude of the USN safety 'hard deck' and how it impaired their training.

I'm sure there are a million things like this in all services. Surely we can use our imaginations and heap on safety regulations until training becomes unrealistic and almost pointless. There's a sweet spot between man/materiel losses and training value, everyone could have a different opinion on where that is.

Group A would point to Group B's appalling training accidents - Group B would claim Group A is just training a bunch of wussies.

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## swampyankee (Feb 3, 2018)

pbehn said:


> Do you have any proof at all for this? Fighting is inherently dangerous but I can put forward a very good argument that proves the top aces in two world wars were cowards, "if it is a fair fight you have done something wrong", they were as much, if not more concerned with their own survival as they were with a "kill". If the USAF is in the position of losing football games by two goals to one they can try to score more or concede less, constructing strategies to concede less is not being "far too obsessed with safety" in fact the strategy worked.



"Coward" is not a synonym for intelligent, nor is "brave" one for stupid. One wants the pilots, who have been trained through a very rigorous and expensive process, to operate very expensive machinery to make intelligent risk-benefit assessments, not just throw themselves into stupid fights to get themselves killed _and the country defeated_. 

The WW2-era veterans I knew were fighting for a specific purpose, which was the defeat of either Japan or nazism. They weren't fighting for glory or out of some stupid chivalric ethic; they were fighting to win.

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## FLYBOYJ (Feb 3, 2018)

Greyman said:


> I've listened to an F-16 pilot complain about the altitude of the USN safety 'hard deck' and how it impaired their training.


And it also saved some lives along the way.


Greyman said:


> I'm sure there are a million things like this in all services. Surely we can use our imaginations and heap on safety regulations until training becomes unrealistic and almost pointless. There's a sweet spot between man/materiel losses and training value, everyone could have a different opinion on where that is.
> 
> Group A would point to Group B's appalling training accidents - Group B would claim Group A is just training a bunch of wussies.


And you also have Group C - "It's better to die than look bad."


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## Greyman (Feb 3, 2018)

FLYBOYJ said:


> And it also saved some lives along the way.



They'd save more lives if they never flew in peacetime at all and stuck to simulators. Ridiculous extreme to make a point - but you get my drift.

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## pbehn (Feb 3, 2018)

Greyman said:


> They'd save more lives if they never flew in peacetime at all and stuck to simulators. Ridiculous extreme to make a point - but you get my drift.


I believe you are close to the mark there with the F 35.


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## FLYBOYJ (Feb 3, 2018)

There needs to be some sought of realistic combat training balanced with a margin of safety. Over the years risk mitigation has evolved almost into a fine art. During the Vietnam War era (from the OP) there was mention of how the safety margin was becoming unrealistic. For one to really understand this, there needs to be a level of knowledge or experience to justify said comments. The safety card is never too great, especially for those who have to take the risks and hopefully return to their families at the end of the day. As the old saying goes "There is never a need to fly directly into a thunderstorm during peacetime."

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## pbehn (Feb 3, 2018)

FLYBOYJ said:


> And it also saved some lives along the way.
> 
> And you also have Group C - "It's better to die than look bad."


That is a mentality that sounds ridiculous but for many reasons does exist. I am not a great viewer of on line videos but this had me hooked, at the time of the Vietnam conflict an instructor and trainee or pilot were less likely to eject from a doomed aircraft over the USA than a pilot shot down in combat.


_View: https://www.youtube.com/watch?v=dyjYp6WT7ww_


from the text intro

The film starts with footage of an F-4 Phantom in a deadly spin, forcing the air crew to eject from the plane. An officer from the Air Force Inspection and Safety Center explains at mark 01:50 that the decision when to eject from an out-of-control aircraft could mean the difference between life and death. From 1949 to 1980, we are informed via a pie chart that there were 4,626 ejections — 82% of them success. Yet from 1976 to 1980 the survival rate had fallen (mark 02:25) due to delayed ejection. A horrific accident involving an F-100 fighter jet careening out of control is seen at 2:40. At 3:30, POV footage from inside an aircraft as an ejection occurs is shown. The ACES II Ejection Seat is seen at 3:48. As the film continues we see numerous crashes, look at the design of an ejection seat, and review statistics on fatality rate by altitude (mark 04:42). The training film continues with detailed narratives on ejection scenarios and archived combat footage from the Vietnam War (07:15) followed by a look at statistics on 1967-1973 combat and mishap ejection survival rates. In peacetime, we are told at mark 07:50, that there seems to be an increase in delayed ejections including failed attempts to gain altitude and lack of confidence in the ejection system. At mark 09:15, a pilot offers a first-hand look at what it’s like to eject from an aircraft as his F-4 lost all hydraulics and started taking an uncontrolled bank. At 11:00, a female pilot who was flying as a student recounts having to eject from a T-38 Talon with her instructor, followed by images of T-38 Talon wreckage. Several more pilots share their experiences starting at mark 11:05 with those interviews accompanied by scenes of aircraft in flight and in crisis. Stressing that time is everything, an officer concludes at mark 21:33, “Wasting those few precious seconds can not only be critical; in the ejection world it can be fatal.”

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## pbehn (Feb 3, 2018)

swampyankee said:


> "Coward" is not a synonym for intelligent, nor is "brave" one for stupid. One wants the pilots, who have been trained through a very rigorous and expensive process, to operate very expensive machinery to make intelligent risk-benefit assessments, not just throw themselves into stupid fights to get themselves killed _and the country defeated_.
> 
> The WW2-era veterans I knew were fighting for a specific purpose, which was the defeat of either Japan or nazism. They weren't fighting for glory or out of some stupid chivalric ethic; they were fighting to win.


That was pretty much what I was trying to say (maybe a bad choice of words). During the Battle of France and Britain the ideal was to be up sun and shoot down the enemy before you were seen. Mass dogfights between groups of fighters rarely achieved anything conclusive, where planes were disabled by a single bullet it was quite possible that bullet came from a friend or foe aiming at someone else. 
One of my favourite quotes was from Bob Doe. "I wasn't fighting for King and Country, I was fighting for my mum, I didn't hate Germans, I just didn't want 'em over here"

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## Zipper730 (Feb 21, 2018)

Greyman said:


> I've listened to an F-16 pilot complain about the altitude of the USN safety 'hard deck' and how it impaired their training.
> 
> I'm sure there are a million things like this in all services. Surely we can use our imaginations and heap on safety regulations until training becomes unrealistic and almost pointless. There's a sweet spot between man/materiel losses and training value, everyone could have a different opinion on where that is.


That's a good point


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## swampyankee (Feb 21, 2018)

FLYBOYJ said:


> There needs to be some sought of realistic combat training balanced with a margin of safety. Over the years risk mitigation has evolved almost into a fine art. During the Vietnam War era (from the OP) there was mention of how the safety margin was becoming unrealistic. For one to really understand this, there needs to be a level of knowledge or experience to justify said comments. The safety card is never too great, especially for those who have to take the risks and hopefully return to their families at the end of the day.



Sometimes, I feel that there are people whose comments have an underlying tenor of "safety is stupid." Obviously, flying has some risks -- the in the US the category "commercial pilot" has a greater rate of work-related fatalities than does police or firefighter (for reference, the greatest fatality rate is for commercial fisherman correction: timber industry workers) --but losing pilots and aircraft because of non-combat losses is a gift to the enemy.



FLYBOYJ said:


> As the old saying goes "There is never a need to fly directly into a thunderstorm during peacetime."



....although there are pilots who have deliberately done exactly that.

Sometimes it seems that NASA has some pilots who not only push the envelope but take a match to it.

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## Shortround6 (Feb 21, 2018)

Back in the 70s when I joined the fire service it was the most dangerous job in America (depending on who you believed) however, better equipment, better training and better safety standards have brought the numbers down. Some of the stuff firefighters did back then was just plain stupid even if "macho". 
A nearby big city had a 'tradition' of the first in engine company (pumper) NOT putting on air packs and advancing the hose as far as they could into the heat/smoke. 2nd in engine took care of water supply to the 1st engine, put on air packs, and went in and took over the hose. Where upon the first-in crew came back out, puked up their guts on the sidewalk and were useless for the rest of the incident, not to mention long term health problems. 
Our smaller dept didn't have the luxury of 3rd and 4th engines showing up so we put on air packs before going in and remained more effective for a longer period of time. It was also common to ride on the rear step (bumper) of the truck. A bit thrilling (unless it was winter) and while we never lost anybody plenty of other depts did. Somebody did a study and found an almost unbelievable number of deaths/injuries due to crashes _while responding!!! _
some years it was higher than the losses actually on the fireground. 
Crashed truck and injured crew puts out NO fires and saves NO victims. 

Injuring (or worse) firefighters on the training ground is really stupid but it took a long time to change.

"What do you mean you don't want to train in the rain? You think fires only happen when it's not raining!!!"

SO out we would go to climb aluminium ladders to 2nd and 3rd floor heights with wet rungs and wet boots. 
Then we would sit in a classroom the next day while the sun shown outside.  

You need some degree of realism while training with more realism introduced after basic skills are mastered. 
However any training officer that bragged about melting a helmet visor in training is a training officer I don't want to train with. 

I started with rubber covered canvas coats and some metal helmets, rubber covered gloves and ended up with nomex coats, pants, hoods and gloves and fiberglass/composite helmets. Air packs went from demand to positive pressure. Radios went from officer only to every man in the crew. 

This took well over 20 years and things were still improving in the last last 10 years after that and hopefully are still improving. 

Brave and skilled shouldn't have to equal stupid.

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## swampyankee (Feb 22, 2018)

Shortround6 said:


> Back in the 70s when I joined the fire service it was the most dangerous job in America (depending on who you believed)
> 
> 
> Brave and skilled shouldn't have to equal stupid.



Brave never equaled stupid; poorly trained and dead does -- or at least did -- cost less than well-trained and alive, leading to rewards for managers


For reference regarding job dangers see 25 most dangerous jobs in America and The Most Dangerous Jobs in America


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## fubar57 (Feb 22, 2018)

I made #1 on both lists, same as Canadian lists

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## swampyankee (Feb 22, 2018)

Right now, I’m way down on that list, although that may change: I teach in a suburb.


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## Zipper730 (Mar 2, 2018)

Okay, let's get back onto rate of turn


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## fubar57 (Mar 2, 2018)

....said he who often heads off in wild tangents

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## Zipper730 (Mar 2, 2018)

Yes, but at least I turned back onto track...


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## Laurelix97 (Mar 11, 2018)

You can calculate the turn rates

For example:
Ki-84
Loaded Weight: 3600kg
Wing Area: 21m2
Air density at sea level: 1.225kg/m3
Flap Area: 2.436m2
Wing Lift Coefficient: (according to its manual)
Flaps at 0 degrees: 1.46 CL_Max
Flaps at 15 degrees: 1.70 CL_Max
Flaps at 30 degrees 1.92 CL_Max

Step 1:
Find out the Lift Force:
Weight (kg) X Gravity
3600 X 9.81 = 35,316 Newtons

Step 2:
Look at the formula and fill in the numbers 






V= Stall Speed
2L = 2x Liftforce (2x 35316)
CL = wing lift coefficient 
p = Air density (kg/m3)
a = Wing Area (m2)

Note:
If you are looking for stall speed without using flaps (0 degrees) you do not add the flap area to the wing area in the calculation. It's only when you start calculating the stall speed with flaps deployed, that's when you add the 2.436m2 to the 21.0m2
So the wing area that will be used for calculating flaps 15 and 30 degrees is (23.436m2)

Step 3:
Do the working out, use scientific calculator which lets you write the entire format. Top is just 2x L, bottom is CL X p X a
The top is divided by the bottom and everything is square rooted.
The answer you will get is the stall speed in m/s, you need to multiply it by 3.6 to convert it to Km/h.

If you're struggling with the math, here's the easiest way.
Airplane Aircraft Wing Lift Design Equations Formulas Calculator - Velocity

Ki-84
At 3600kg weight , Sea level
Stall speed is:
Flaps at 0 degrees: 156km/h 
Flaps at 15 degrees (Combat): 137km/h
Flaps at 30 degrees (Landing): 129km/h

Step 4:
Work out the Power to weight ratio
Weight (Kg) / Power (HP)
3600 / 1990 = 1.81kg/HP 

Step 5:
Now you can compare the turn rate against other planes.
Yak-3
2692kg loaded weight
1300hp engine 
That's 2.07kg/HP power to weight ratio

Yak-3 stall speed at 2692kg, sea level, No flaps (0 degrees)
163km/h

Which ever plane has lower stall speed, that plane has smaller turn radius and sharper turns. This is the initial turn.
Ki-84 not only has lower stall speed (better initial turn) than Yak-3, it has better power to weight ratio than Yak-3 (carries less weight per horsepower). This means the Ki-84 sustains it's speed better than Yak-3.

There are instances where planes have very good initial turn (they turn very well with energy) but their engine is underpowered and as soon as they get into prolonged turns, they turn into whales that do small turn radius but they take long time to complete one because the plane is fighting stall thus the plane isn't turning efficiently because it doesn't have enough energy to perform manuevers. One example would be the F6F-3. 

Yak-3 sustained turn (no flaps, 1000m altitude)
18 seconds to complete 360 horizontal turn
-
Ki-84 is rated at 17 seconds 
La-7 is rated at 19 seconds

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## Greyman (Mar 11, 2018)

If I told you how far that all went over my head you wouldn't believe me.

If it were up to me to invent things we wouldn't even have scissors yet.

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## Zipper730 (Mar 11, 2018)

Laurelix97 said:


> You can calculate the turn rates


Just to be clear, does the coefficient of lift figure include the downforce of the tail? As for g-load, I would just multiply 9.81 x (g-load) right?


> Ki-84
> Loaded Weight: 3600kg
> Wing Area: 21m2
> Air density at sea level: 1.225kg/m3
> ...


And for this I got...

Flaps 0: 43.3657270825 m/s, or 97.01 mph
Flaps 15: 38.2035146891 m/s, or 85.46 mph
Flaps 30: 35.7964821077 m/s, or 80.07 mph

I'm not sure how you factor in indicated airspeed with true airspeed, and mach number with temp

I was looking at a graph and found something interesting: Gravity varies with altitude...

0 m = 9.807 (listed, actually 9.80665) m/s
1000m = 9.804 m/s
2000m = 9.801
3000m = 9.797
4000m = 9.794
5000m = 9.788
6000m = 9.785
7000m = 9.792
8000m = 9.779
9000m = 9.776
I didn't go any further: Will this factor in stall speed and g-loads?


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## Shortround6 (Mar 11, 2018)

I think the variation in gravity is the least of your worries/considerations. 
Come on, gravity at 9000 meters is 0.3% of gravity at sea level?
10,000lb airplane will act like a 9970lb plane at 9000 meters?


You are going to get more variation in air density on cold and hot days. Let alone fuel burn and oil consumption. 
ANd if you are figuring things that close you better being using pilots who are 100% clones of each other and planes that have 100% identical fit and finish.


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## swampyankee (Mar 11, 2018)

Pitching moment does, as it will influence trim drag. Lift coefficient also comes in as higher lift coefficient means greater induced drag; this is why deltas have, historically, bled off speed quickly in air combat. Maneuvering flaps will probably make sustained — vs instantaneous— turn rate worse, as the increase trim drag and tend to be partial span, so they increase induced drag.


Lift coefficient has one direct effect on sustained turn rate: induced drag increases by lift coefficient squared, so the induced drag in a 2-g turn is 4 times what it is in level flight at the same speed and altitude. There's also a second order effect from the fact that the horizontal tail needs to provide lift to maintain the proper angle of attack for the new lift coefficient, which increases trim drag. Propellers ahead of the c/g are destabilizing, which could be another problem, and could require more trim.

Lift flaps can increase instantaneous turn rate, as they can increase achievable lift coefficient, but since they're usually part span, they will increase induced drag -- there will be a big vortex where they end -- and, since they increase camber, they will increase the nose down pitching moment and, so increase the trim drag.


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## pbehn (Mar 11, 2018)

Zipper730 said:


> I was looking at a graph and found something interesting: Gravity varies with altitude...
> 
> 0 m = 9.807 (listed, actually 9.80665) m/s
> QUOTE]
> .



You do have a problem with units Zipper, acceleration due to gravity is m/s²

From Wiki
The apparent force of gravity on Earth is the resultant (vector sum) of two forces:[30] (a) The gravitational attraction in accordance with Newton's universal law of gravitation, and (b) the centrifugal force, which results from the choice of an earthbound, rotating frame of reference. The force of gravity is the weakest at the equator because of the centrifugal force caused by the Earth's rotation and because points on the equator are furthest from the center of the Earth. The force of gravity varies with latitude and increases from about 9.780 m/s2 at the Equator to about 9.832 m/s2 at the poles​


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## Zipper730 (Mar 11, 2018)

Shortround6 said:


> I think the variation in gravity is the least of your worries/considerations.


I just didn't know to what degree it varied with altitude. I know in space you usually see in orbit, zero g because you're basically in a constant state of fall except you're moving so fast that you never actually crash into the Earth (well eventually you do, it's called orbital decay, but...)


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## Shortround6 (Mar 11, 2018)

What keeps things in orbit is centrifugal force countering gravity. Orbital decay happens because most low orbit satellites/objects are not in a true vacuum and the very low density air is causing drag which slows the satellite/object below the speed needed to stay in orbit, the lower the satellite/object "falls" the higher the density of the "air", the more drag, the faster the speed bleeds off and then just keep repeating. 

I would also note that even P-40 fighters could vary by over 100lbs (extreme) from one aircraft to another on the production line (empty weight) so trying to figure gravity to 3-4 decimal places when computing performance is pretty much a waste of time.

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## pbehn (Mar 11, 2018)

Shortround6 said:


> View attachment 485668
> 
> 
> What keeps things in orbit is centrifugal force countering gravity. Orbital decay happens because most low orbit satellites/objects are not in a true vacuum and the very low density air is causing drag which slows the satellite/object below the speed needed to stay in orbit, the lower the satellite/object "falls" the higher the density of the "air", the more drag, the faster the speed bleeds off and then just keep repeating.
> ...


If the plane is on full power, then for example a Merlin used 150 gallons per hour, which means it is losing something like 1 lb per second in fuel, it needs a computer or some calculus to make sense of it.


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## DarrenW (Mar 12, 2018)

Laurelix97 said:


> There are instances where planes have very good initial turn (they turn very well with energy) but their engine is underpowered and as soon as they get into prolonged turns, they turn into whales that do small turn radius but they take long time to complete one because the plane is fighting stall thus the plane isn't turning efficiently because it doesn't have enough energy to perform manuevers. One example would be the F6F-3.



Hi Laurelix97,
While I can appreciate your scientific approach concerning the determination of an aircraft's turn rate, I would have to disagree with the comment that the F6F-3 was "underpowered". Of the eleven US fighters discussed in Dean's _America's Hundred Thousand_, it had one of the lowest power loadings at the specified altitudes:

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## DarrenW (Mar 12, 2018)

Dean did some calculating of his own regarding the turn_ radius_ of various US fighters in _America's Hundred Thousand_. He basically was looking at two factors, wing loading and maximum wing CL, under the assumption that the aircraft had enough power to sustain the turn and not sink in altitude. With this information he placed the FM-2 as best of the eleven fighters, giving it an arbitrary 100%, and ranked the others in comparison to it accordingly.

For instance, the P-63 came in second at being able to achieve 124% of the FM-2's radius, followed by the P-61 at 133%, then the F6F at 138%, the P-51 at 179%, and so on. Even more surprising to me than the Black Widow's ranking was the placement of the F4U in dead last. Dean surmises that the relatively lower maximum CL, due to the spoiler on the right wing, was the culprit and apparently NACA testing supports this notion.

I figure that turn radius is just as important as turn rate, because if you can't turn tight enough to bring your guns to bear on an enemy than being able to turn at a high rate of speed really amounts to nothing.

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## Zipper730 (Mar 13, 2018)

What does minimum turnr-radius index number mean?


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## swampyankee (Mar 13, 2018)

DarrenW said:


> Dean did some calculating of his own regarding the turn_ radius_ of various US fighters in _America's Hundred Thousand_. He basically was looking at two factors, wing loading and maximum wing CL, under the assumption that the aircraft had enough power to sustain the turn and not sink in altitude. With this information he placed the FM-2 as best of the eleven fighters, giving it an arbitrary 100%, and ranked the others in comparison to it accordingly.
> 
> For instance, the P-63 came in second at being able to achieve 124% of the FM-2's radius, followed by the P-61 at 133%, then the F6F at 138%, the P-51 at 179%, and so on. Even more surprising to me than the Black Widow's ranking was the placement of the F4U in dead last. Dean surmises that the relatively lower maximum CL, due to the spoiler on the right wing, was the culprit and apparently NACA testing supports this notion.
> 
> ...



Most of the lift coefficients they're showing -- considerably over 2 -- are _highly_ suspect. While there is some momentary increase in lift coefficient when there's a rapid change in angle of attack, such as during a landing flare, I would be very surprised if any of these aircraft could demonstrate no-flap instantaneous lift coefficients over 1.75 in turning flight. Indeed, the only lift coefficient in that table that I find plausible is the Corsair's.


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## CORSNING (Mar 14, 2018)

I figure that turn radius is just as important as turn rate,

*That depends on what game you are playing. Think A6M5 vs Yak-3, there
is no question that the A6M5 will outturn the Yak-3 IF they both limit their
speeds to 225 mph. This all changes if the Yak decides to accelerate up
to higher speeds. At 320 mph. the Yak-3 controls are still fully functional
where as the Zero's are not. Once into a turn at these speeds the A6M 
still has a smaller turning radius, BUT the Yak-3's much greater roll rate
allows it to go into the turn infinitely faster and continue on to complete 
its turn quicker. This allows the Yak-3 with its much greater climb rate
at 1,000 m to gain quite a height advantage....and so on.*


because if you can't turn tight enough to bring your guns to bear on an enemy than being able to turn at a high rate of speed really amounts to nothing.

*There are other ways to bring your guns to bear as I tried to point out above.*

*There is another consideration that makes quite a difference also, engine capability.
While the Yak-3 can pretty much have its way with the A6M5 at 1,000 m. Its Klimov
engine's power tends to peter out at ALTITUDE. This is another great factor to take
into consideration. While the cleaner design of the inline Yak allows its top speed to
remain 384 mph. at 6,000 m. compared to the A6M5's 350, the Sakae 31A engine's
output at that altitude gives it a better climb rate of 2,620 fpm vs. 2,250 fpm. of the 
very close in weight Yak.*

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## Zipper730 (Mar 14, 2018)

CORSNING said:


> I figure that turn radius is just as important as turn rate,
> 
> *That depends on what game you are playing. Think A6M5 vs Yak-3, there
> is no question that the A6M5 will outturn the Yak-3 IF they both limit their
> ...


Okay, so let's divide this into the turn radius as well as rate of turn

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## DarrenW (Mar 14, 2018)

Zipper730 said:


> What does minimum turnr-radius index number mean?



It is calculated by dividing an aircraft's wing loading by it's maximum coefficient of lift. Dean surmises that it's proportional to minimum turn radius.

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## Zipper730 (May 16, 2018)

pbehn said:


> At the other end of the "ad absurdum" scale the FW190 could out manoeuvre the Mosquito at all speeds except maximum.


Wait, I thought the Mosquito maneuvered better at higher altitudes...



swampyankee said:


> Advance ratio is airspeed (ft or meters per second) divided by (diameter (ft pr meters) times rate of rotation(rev/sec)


Where would you find RPM rates for WWII aircraft?


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## fubar57 (May 16, 2018)

WWII Aircraft Performance

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## Zipper730 (Jul 2, 2018)

What do you guys think about this one?


_View: https://www.youtube.com/watch?v=Ir5J9X3txz4_


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## parsifal (Jul 3, 2018)

I thought this was interesting as a non-technical assessment

P-40 and Zero

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## Zipper730 (Aug 8, 2018)

There is something interesting here to potentially make note of when it comes to comparing the F4U vs the P-51: They might very well have based the coefficient of lift on the P-51 operating with flaps and the F4U without.


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## pbehn (Aug 9, 2018)

Zipper730 said:


> Wait, I thought the Mosquito maneuvered better at higher altitudes...
> 
> ?


I read an account of a Mosquito bomber avoiding an Fw 190 at high altitude by going into a shallow high speed dive, the Mosquito just had slightly better control than the Fw which couldn't get a shot on target, at that height and speed the Fw doesn't have much time before it runs short of fuel.


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## Zipper730 (Aug 9, 2018)

fubar57 said:


> WWII Aircraft Performance


Good point, I'm looking up figures for most of the major aircraft. I figure climb-speed and maximum speeds would be the most useful


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## Zipper730 (Aug 13, 2018)

Okay, so I'll start with the Hawker Hurricane & Supermarine Spitfire and proceed from there...

Hawker Hurricane Prototype K.5083 (In the process of being edited... editing will be made under presumption of 0.477 gear ratio)

Speed Trials (Altitude/TAS/Engine RPM/Propeller RPM/Boost/Advance Ratio)
0'...........253.0 MPH...2505 / 1194.9 RPM...20.7.. PSI / 42.15" MAP.....1.6892797329
1000'.....257.5 MPH...2535 / 1209.2 RPM...20.7.. PSI / 42.15" MAP.....1.6989791546
2000'.....261.5 MPH...2560 / 1221.1 RPM...20.7...PSI / 42.15" MAP.....1.708521737
3000'.....265.5 MPH...2590 / 1235.4 RPM...20.7...PSI / 42.15" MAP.....1.7145633732
5000'.....274.0 MPH...2645 / 1261.7 RPM...20.7...PSI / 42.15" MAP.....1.7326612674
6500'.....280.5 MPH...2685 / 1280.7 RPM...20.7...PSI / 42.15" MAP.....1.747339748
10000'...295.5 MPH...2785 / 1328.4 RPM...20.7...PSI / 42.15" MAP.....1.7746841329
13000'...308.0 MPH...2870 / 1369... RPM...20.7...PSI / 42.15" MAP.....1.794971678
15000'...314.0 MPH...2930 / 1397.6 RPM...20.7...PSI / 42.15" MAP.....1.7924655121
16200'...315.0 MPH...2960 / 1411.9 RPM...20.7...PSI / 42.15" MAP*....1.7799492645
16500'...315.0 MPH...2960 / 1411.9 RPM...20.4...PSI / 41.5"...MAP......1.7799492645
18000'...313.5 MPH...2940 / 1402.4 RPM...19.0...PSI / 38.7"...MAP.....1.7835241545
20000'...311.0 MPH...2910 / 1388.1 RPM...17.4...PSI / 35.4"...MAP.....1.7875416952
23000'...306.0 MPH...2860 / 1364.2 RPM...15.25 PSI / 31.05" MAP.....1.7895513884
26000'...298.5 MPH...2795 / 1333.2 RPM...13.3...PSI / 27.1"...MAP.....1.7862872728
28000'...291.5 MPH...2745 / 1309.4 RPM...12.05 PSI / 24.5"...MAP.....1.7761718835
30000'...282.5 MPH...2680 / 1278.4 RPM...10.8...PSI /.21.99" MAP....,1.7630817046

Climbing Trials (Altitude/Climb/TAS/Engine RPM/Propeller RPM/Boost/Advance-Ratio)
0'...........2550 fpm...151.5 mph...2100 RPM / 1001.7.,.,.,20.7...psi / 42.15" MAP.....1.2066522270
1000'.....2600 fpm...154.0 mph...2125 RPM / 1013.625..20.7...psi / 42.15" MAP.....1.2121338155
2000'.....2650 fpm...156.0 mph...2125 RPM / 1013.625..20.7...psi / 42.15" MAP.....1.2278758131
3000'.....2710 fpm...158.5 mph...2180 RPM / 1039.86.,,.20.7...psi / 42.15" MAP.....1.2160783413
5000'.....2810 fpm...163.5 mph...2235 RPM / 1066.095..20.7...psi / 42.15" MAP.....1.2235705352 
6500'.....2880 fpm...167.0 mph...2275 RPM / 1085.175..20.7...psi / 42.15" MAP.....1.2277893186
7600'.....2950 fpm...170.0 mph...2300 RPM / 1099.485..20.7...psi / 42.15" MAP*....1.2335784456
10000'...2680 fpm...173.5 mph...2305 RPM / 1099.485..18.85 psi / 38.4"...MAP.....1.258975649
13000'...2370 fpm...177.5 mph...2305 RPM / 1099.485..16.95 psi / 34.5"...MAP.....1.2880010241 
15000'...2150 fpm...181.0 mph...2305 RPM / 1099.485..15.80 psi / 32.2"...MAP.....1.3133982274
16500'...2000 fpm...183.0 mph...2300 RPM / 1097.1.,.,.,15.00 psi / 30.5"...MAP.....1.3307976778 
18000'...1840 fpm...186.5 mph...2300 RPM / 1097.1,.,.,.14.20 psi / 28.9"...MAP.....1.3562500925
20000'...1620 fpm...189.5 mph...2295 RPM / 1094.715..13.20 psi / 26.9"...MAP.....1.3810687712
23000'...1310 fpm...195.0 mph...2285 RPM / 1089.945..11.80 psi / 24.0"...MAP.....1.4273720475
26000'.....990 fpm...199.5 mph...2265 RPM / 1080.405..10.40 psi / 21.2"...MAP.....1.4732059843
28000'.....790 fpm...204.0 mph...2245 RPM / 1070.865..........N/A / N/A...................1.5198565615
30000'.....570 fpm...208.0 mph...2210 RPM / 1054.17............N/A / N/A...................1.5741997604

Notes: Diameter estimated at 11.03"
Hawker Hurricane Mk.I will be next


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## Zipper730 (Dec 19, 2018)

Just to be clear on something, and this might sound stupid: The listed RPM -- is that the propeller's RPM or just the engine and how do you conclude the propeller's RPM if you have the engine RPM?


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## pbehn (Dec 19, 2018)

Zipper730 said:


> Just to be clear on something, and this might sound stupid: The listed RPM -- is that the propeller's RPM or just the engine and how do you conclude the propeller's RPM if you have the engine RPM?


Reduction ratio here Rolls-Royce Merlin. Engine data.


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## Zipper730 (Dec 20, 2018)

pbehn said:


> Reduction ratio here Rolls-Royce Merlin. Engine data.


The reduction gears seem to run through a range -- is this do deal with different propeller installations?


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## pbehn (Dec 20, 2018)

Zipper730 said:


> The reduction gears seem to run through a range -- is this do deal with different propeller installations?


I post on a forum I am not an engineer of aircraft, as a guess I would say its different use/ prop diameter.


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## Zipper730 (Jan 11, 2019)

Okay, speed and climb-trials are finished now I'll start setting up data on the Hurricane Mk.I... since I can't find much data on the twin-pitch propellers due to an inadequate supply of data, I'll go right to the constant-speed propeller data.

A/C:...Hurricane Mk.I (L.2026)
Date:..6/12/1940
Weight: 6316 lbs

Climb-Trials

*ALT*........*R/C*.....*TAS*.&&*IAS*...\\*PEC* *&* *CEC*...*CAS*.....*RPM*...*Boost* & *MAP*.....*Diameter*
0'........,,,2500*.............................................................2600.\\+6.25. & 42.65"....10'9"
1000'..,,,2610\\\167......169.5...-4.8 & -0.1............\\...2600.\\+6.25. & 42.65".... "..."
2000'..,,,2615\\\169.5...169.5...-4.8 & -0.1...........\\....2600.\\+6.25. & 42.65".... "..."
3000'..,,,2620\\\172......169.5...-4.8 & -0.1.................2600.\\+6.25. & 42.65".... "..."
5000'..,,,2625\\\177.5...169.5...-4.8 & -0.2.................2600.\\+6.25. & 42.65".... "..."
6500'..,,,2630\\\181.5...169.5...-4.8 & -0.3.................2600.\\+6.25. & 42.65".... "..."
10000',,,2640\\\191.5...169.5...-4.8 & -0.5.................2600.\\+6.25. & 42.65".... "..."
11600',,,2645\\\195......169.5...-4.8 & -0.6.................2600.\\+6.25. & 42.65".... "..."
13000',,,2485\\\197.5...167......-4.6 & -0.7.................2600.\\+5.25. & 40.72".... "..."
15000',,,2250\\\200.5...164......-4.3 & -0.7.................2600.\\+3.9... & 37.97".... "..."
16500',,,2080\\\202.5...161.5...-4.1 & -0.8.................2600.\\+2.95. & 36.14".... "..."
18000',,,1910\\\205......159.5...-3.8 & -0.9.................2600.\\+0.8... & 34.21".... "..."
20000',,,1675\\\209......157......-3.8 & -1.0.................2600.\\+2.0... & 31.97".... "..."
23000',,,1330\\\214......152.5...-3.2 & -1.1.................2600\\\-0.95...& 28.61"... "..."
26000'..,,,990\\\219......148......-2.7 & -1.2.................2600~~-2.55..& 25.45".... "..."
28000'..,,,755\\\223......145......-2.4 & -1.3.................2600\\\-3.6.... & 23.41".... "..."
30000'..,,,530\\\227......142......-2.0 & -1.4.................2600\\\-4.6.... & 21.48".... "..."

Speed Trials

*ALT*........*TAS*.&&*IAS*...\\*PEC & CEC*...*CAS*.....*RPM*...*Boost & MAP*.....*Diameter*
0'.......................................................................3000...+6.25. & 42.65"....10'9"
1000'.................................................................3000...+6.25. & 42.65"...."..."
2000'.................................................................3000...+6.25. & 42.65"...."..."
3000'.................................................................3000...+6.25. & 42.65"...."..."
5000'..,,,276......267......-10.0 & -0.8.................3000...+6.25. & 42.65"...."..."
6500'..,,,280.5...265.5...-10.0 & -1.0.................3000...+6.25. & 42.65"..~"..."
10000'...291.5...262......-10.0 & -1.7.................3000...+6.25. & 42.65"..~"..."
13000'...301......258.5...-10.0 & -2.2.................3000...+6.25. & 42.65"..~"..."
15000'...307......256......-10.0 & -2.6.................3000...+6.25. & 42.65"..~"..."
16500'...312......254.5...-10.0 & -2.9.................3000...+6.25. & 42.65"..~"..."
17750'...316......252.5.....-9.9 & -3.2.................3000...+6.25. & 42.65"..~"..."
18000'...316......252........-9.9 & -3.2.................3000...+6.05. & 42.25"..~"..."
20000'...314.5...243........-9.8 & -3.4.................3000...+4.85. & 39.8"....~"..."
23000'...310.5...228........-9.2 & -3.4.................3000...+2.5... & 35.02...~"..."
26000'...305......212.5.....-8.3 & -3.4.................3000...+0.75. & 31.46...~"..."
28000'...299.5...200.5.....-7.4 & -3.3.................3000....-0.35. & 29.22..~"..."
30000'...292.5...188.5.....-6.6 & -3.2.................3000....-1.4... & 27.08..~"..."

The climb-figures for the Hurricane are unfortunately limited to 2600 rpm with +6.25 boost, if anybody knows how to calculate for 3000 rpm, reasonably speaking, I'd love to hear it: I figure I could graph the speeds between 0 & 4000 feet provided it follows some form of non exponential relationship.

Also I'm not sure what to make of the position error calculation and compressibility error calcuation. I figured I could just add or subtract the error and get the correct CAS, but the numbers don't seem to work.


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## Zipper730 (Feb 6, 2019)

Snowygrouch
& 

 swampyankee


What formulas do you use to convert the advance ratio figures into thrust?


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## swampyankee (Feb 7, 2019)

Zipper730 said:


> Snowygrouch
> &
> 
> swampyankee
> ...




Prop efficiency is advance ratio times (thrust coefficient divide by power coefficient), so thrust coefficient is equal to (efficiency times power coefficient) divided by advance ratio. See, for example, here: Aerodynamic Characteristics of Propellers

I’ll put the formula up later today; I have to convert them to images to post them.

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## Zipper730 (Feb 8, 2019)

I'm looking at some figures and I'm getting some conflicting data as to gear-ratios and propeller diameter: The Hurricane prototype was stated to have an 11'3" diameter, so I guess I'll rework the numbers; as for the twin-pitch set-up they listed 11.03 feet. It should be what it sounds like 11 feet and 3/100ths of a foot -- is this in anyway an error of 11'3"?


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## Zipper730 (Feb 18, 2019)

swampyankee said:


> Prop efficiency is advance ratio times (thrust coefficient divide by power coefficient), so thrust coefficient is equal to (efficiency times power coefficient) divided by advance ratio.


Okay, so at the penalty of sounding stupid

What does thrust coefficient mean in plain english?
What does power coefficient mean in plain english?
Out of all of this, where does exact thrust figures come out?
Additionally, I could use figures that are based around imperial/english units () since those were heavily used in WWII.

Thanks


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## swampyankee (Feb 18, 2019)

Zipper730 said:


> Okay, so at the penalty of sounding stupid
> 
> What does thrust coefficient mean in plain english?
> What does power coefficient mean in plain english?
> ...



Thrust coefficient, power coefficient, and advance ratio are non-dimensional coefficients; any consistent set of units could be used. Off the top of my head, I can't give you typical values for these.

Some sources could be: 
Slavik, S. "Preliminary Determination of Propeller Aerodynamic Characteristics for Small Aeroplanes", https://ojs.cvut.cz/ojs/index.php/ap/article/viewFile/558/390
and
Hartman, Edwin P and Biermann, David, "The Aerodynamic Characteristics of Four Full-Scale Propellers Having Different Plan Forms", https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930091718.pdf

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## Zipper730 (Feb 18, 2019)

Just to be clear, what I'm trying to compute is thrust -- pounds of thrust, newtons, etc, at given speeds. If you want to determine sustained turning performance and climb rates you need to know how much OOOMPF comes out the engines -- with jets it's just "pounds of thrust" or "newtons" depending on what measurement system you're using. I'm trying to get figures like that.


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## pbehn (Feb 18, 2019)

Zipper730 said:


> Just to be clear, what I'm trying to compute is thrust -- pounds of thrust, newtons, etc, at given speeds. If you want to determine sustained turning performance and climb rates you need to know how much OOOMPF comes out the engines -- with jets it's just "pounds of thrust" or "newtons" depending on what measurement system you're using. I'm trying to get figures like that.


With a jet engine the pounds of thrust is not a constant either, it varies depending on all sorts of variables.

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## Zipper730 (Feb 19, 2019)

pbehn said:


> With a jet engine the pounds of thrust is not a constant either, it varies depending on all sorts of variables.


True, but you know what I mean -- I'm trying to determine pounds of thrust.

Advance ratios seem fairly generalized speed versus engine power and RPM. It seems to include exhaust thrust as that's part of the speed. I just need some way to take the advance ratios and turn that into thrust numbers.


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## pbehn (Feb 19, 2019)

Zipper730 said:


> True, but you know what I mean -- I'm trying to determine pounds of thrust.
> 
> Advance ratios seem fairly generalized speed versus engine power and RPM. It seems to include exhaust thrust as that's part of the speed. I just need some way to take the advance ratios and turn that into thrust numbers.


You have been given them, as with almost every subject you want a simple solution to very complex issues. A jet engine thrust obviously changes with altitude, it changes with temperature, it changes with speed and it changes while manouvering from what I have read as airflow to the inlet changes. So for a jet you need an equation for actual thrust, the quoted thrust for a jet will be in a certain test condition, used to compare to other engines in the same/similar test condition.


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## Zipper730 (Feb 20, 2019)

pbehn said:


> You have been given them


No, I haven't -- at least I don't think I have

This link: Aerodynamic Characteristics of Propellers talks about efficiency, but I don't know what kind of efficiency we're talking about -- what does an efficiency of 0.8 mean? 80% of what?

This link: https://ojs.cvut.cz/ojs/index.php/ap/article/viewFile/558/390 talks about the propeller efficiency provided the blade angles and geometry are known. This is not data I have. I'm just trying to convert he advance ratio into thrust. Is there anyway to do that -- if the answer is no, I can probably still create some large graphs that would provide some use as they're large and highly detailed but would tell me I could avoid bothering trying to compute thrust; if yes -- I'm just trying to find a thrust figure.

T/W helps one determine the angle you could climb at without loss of speed, and would probably also help determine what would happen if the horsepower were increased and decreased. I'm sure that would be useful to somebody.


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## pbehn (Feb 20, 2019)

Zipper730 said:


> No, I haven't -- at least I don't think I have
> 
> This link: Aerodynamic Characteristics of Propellers talks about efficiency, but I don't know what kind of efficiency we're talking about -- what does an efficiency of 0.8 mean? 80% of what?
> 
> ...


Efficiency is how good something is at doing something. If a gear box and differential is 90% efficient then 90% of the power going in is transmitted to the wheels, the rest is lost. I would say the rest of it requires a lot of knowledge/experience like a degree and cant be imparted in a single post. The blade angle of a CV prop depends on the power load at the time I believe.


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## Zipper730 (Feb 20, 2019)

pbehn said:


> Efficiency is how good something is at doing something.


I'm aware of that, the problem is 80% of what?

The issue isn't an understanding of something like efficiency, I'm just not even sure what the 80% even is for? Thrust to drag? And where do you get the thrust and drag from -- at least if I knew the drag I could probably get the thrust right?


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## pbehn (Feb 20, 2019)

Zipper730 said:


> I'm aware of that, the problem is 80% of what?
> 
> The issue isn't an understanding of something like efficiency, I'm just not even sure what the 80% even is for? Thrust to drag? And where do you get the thrust and drag from -- at least if I knew the drag I could probably get the thrust right?


I thought you were discussing propellors?

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## swampyankee (Feb 20, 2019)

Zipper730 said:


> I'm aware of that, the problem is 80% of what?
> 
> The issue isn't an understanding of something like efficiency, I'm just not even sure what the 80% even is for? Thrust to drag? And where do you get the thrust and drag from -- at least if I knew the drag I could probably get the thrust right?


 Efficiency is defined as useful work out divided by energy in. For a propeller, that would be airspeed (in feet per second) times thrust (in pounds) divided by (horsepower multiplied by 550) or, equivalently, airspeed (in meters per second) times thrust (in newtons) divided by power (in watts).


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## Zipper730 (Feb 20, 2019)

swampyankee


Okay, fps x pounds/horsepower*550? or (fps*pounds)/horsepower*550? I'm curious if this is derived from advance ratio or another formula?


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## swampyankee (Feb 20, 2019)

Zipper730 said:


> swampyankee
> 
> 
> Okay, fps x pounds/horsepower*550? or (fps*pounds)/horsepower*550? I'm curious if this is derived from advance ratio or another formula?


(Fps time pounds)/(550* horsepower)

Velocity times force is equal to power, in ft-lbf/sec. Multiplying horsepower by 550 gives ft-lbf/sec

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## pbehn (Feb 21, 2019)

pbehn said:


> I thought you were discussing propellors?


A propeller produces thrust but it also suffers drag and creates sound and some heat itself. The resultant thrust of the whole propeller is what is used in thrust drag calculations for the aircraft itself. Unless you are precise with terms and units its difficult to actually know what you are asking about.


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## ODonovan (Feb 21, 2019)

I'm coming in at the end of this, and don't have time to read through all the previous messages. Family aggro prevents that, unfortunately. I do want to leave a couple observations, for what they're worth.

P-47s were NOT bad turn fighters. See the battle over Asch Airfield (aka Y-29), during Operation Bodenplatte. The Germans lost 28 109s and 190s, some to American AAA, but 14 or more were actually air to air kills. The Americans lost one P-47 and no P-51s. This was in a low altitude turning fight around the slag heaps near the airfield.

A6Ms (Zero) could duck and dodge, but were not very good in sustained turns. They were built so lightly that at anything over about 6Gs, their wings would start to warp and could end up breaking off. That's also why they weren't very good in dives. People don't think much of the F4F Wildcat, but even in 1942 it had almost a 6:1 kill ratio, many of those being against the Zero.



-Irish


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## Elvis (Feb 22, 2019)

Zipper730 said:


> Since there are a couple of polls about what planes were the best dog-fighters, and in those days dog-fighting didn't just mean any close in fight with guns, but specifically fights that involved rapid turning.
> 
> I figure there's gotta be some way of organizing all of this data into a single source: I don't claim to know everything about WWII aircraft (I actually know fairly little), but from what I've gathered so far some of the best turning planes would include the following
> 
> ...


Somewhere, in some old obscure thread that I have yet to locate, there was a link to a website that included some tests the Russians did that helped them determine how good of a fighter the planes of the time were.
The test was how quickly they could navigate though a 180 degree turn at 2000(?) meters altitude.
I remember a number of the more popular fighters that are often quoted at this site actually didn't turn all that fast. I think most were in the upper teens to the mid 20 second range.
I seem to remember planes like the 109 and the P-51 did it in something like 22-25 seconds. The P40 and maybe the Spitfire were more in the 17-19 second range. One that did surprisingly well was the Brewster Buffalo (B239). It performed the task in something like 7 seconds.
I wish I could find the website that had that info, but have never been able to relocate it.
It could be that the site no longer exists, as the thread I saw that link in is over 10 years old now.
...anyway, those tests might be something to search for (could be they're mentioned at other websites) in compiling the information you require.


Elvis

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## Zipper730 (Feb 22, 2019)

swampyankee said:


> (Fps time pounds)/(550* horsepower)
> 
> Velocity times force is equal to power, in ft-lbf/sec. Multiplying horsepower by 550 gives ft-lbf/sec


And this gives pounds of thrust?


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## Shortround6 (Feb 22, 2019)

The trouble (for me anyhow) is that these turn times are a snapshot out of a movie and a fuzzy one at that. 

The British calculated a turn chart for the Spitfire I at 12,000ft

at a bit over 18 seconds in time the Spitfire was _supposed_ to be able turn 360 degrees on a 1600ft radius (not diameter) at 6 Gs while doing 315-320mph (corrected.

at the other end of the chart it was supposed to be able to turn 360 degrees in the same time on an 800 ft radius at a bit over 3 Gs and doing a bit over 150mph. 

Now a big problem is that the Spitfire could not actually do either one (or anything in between ) *and *maintain speed and/or altitude. Either speed would decline as the turn was made (increasing the turning time) or a downward spiral would have to be made in order to maintain speed. 

See; http://www.spitfireperformance.com/spit109turn.gif

changes in engine, propeller, weight of aircraft and altitude (or more properly altitude density) will affect things. 

Please note the curve marked "angle of straight climb" which pretty much marks the line between slowing down/descending and being able to climb while turning. The further above the line the more you have to descend to maintain speed. the further below the line the more you can climb while turning. 

Shortest time for Spitfire (at 12,000ft) while maintaining height/speed seems to be about 19.5 seconds right at the edge of stall while pulling about 2.6-2.7 Gs on a just under 700ft radius. 

BTW I would hazard a guess that the Buffalo in no way could manage a 360 turn in 7 seconds. I might well believe a misprint in which they left out a numeral 1 (17 seconds) which is still quite good.


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## Elvis (Feb 22, 2019)

Shortround,

180 degrees, not 360.


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## Shortround6 (Feb 22, 2019)

Elvis said:


> Shortround,
> 
> 180 degrees, not 360.


 something seems off then, as the Spitfire and 109 could both do a 180 in 7-8 seconds if they bled off speed or altitude (or both).

If they maintained speed and altitude then they could do a 180 in 10-12 seconds (at 12,000ft not 2000 meters) and with lower powered engines unless the russians were testing an Allison powered Mustang. 

I might but the B239 being able to out turn the later aircraft but out turning them by a factor of 3 takes an awful lot of swallowing.


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## Elvis (Feb 22, 2019)

I know you're just trying to separate the BS from actual facts.
If you can find the thread and the link, please, post it here.
I even just tried to find the site and have come up with zilch, but I know I've been to that site and read the account myself, although a long time ago.
From what I remember, the planes simply came into the turn at 2000 meters and made a U-turn as fast as they possibly could.
Apparently, allied generals were on hand as well, to witness the event.
As for the B-239's accomplishment, it could be the factor of a lighter aircraft (less than 1/2 the weight of a P-51D) generating less stress (centrifugal force) on the frame (and wings) and thus, would be able to come into a turn harder and maintain that speed better.....of course, it also means less momentum, so one has to push the engine harder, but if the airplane is capable of doing it....


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## tyrodtom (Feb 22, 2019)

ODonovan said:


> I'm coming in at the end of this, and don't have time to read through all the previous messages. Family aggro prevents that, unfortunately. I do want to leave a couple observations, for what they're worth.
> 
> P-47s were NOT bad turn fighters. See the battle over Asch Airfield (aka Y-29), during Operation Bodenplatte. The Germans lost 28 109s and 190s, some to American AAA, but 14 or more were actually air to air kills. The Americans lost one P-47 and no P-51s. This was in a low altitude turning fight around the slag heaps near the airfield.
> 
> ...


The


ODonovan said:


> I'm coming in at the end of this, and don't have time to read through all the previous messages. Family aggro prevents that, unfortunately. I do want to leave a couple observations, for what they're worth.
> 
> P-47s were NOT bad turn fighters. See the battle over Asch Airfield (aka Y-29), during Operation Bodenplatte. The Germans lost 28 109s and 190s, some to American AAA, but 14 or more were actually air to air kills. The Americans lost one P-47 and no P-51s. This was in a low altitude turning fight around the slag heaps near the airfield.
> 
> ...



The aircraft seems to always get the credit for accomplishments due to pilot skill.

A high % of the Luftwaffe pilots who were involved in the Bodenplatte operation were low time , inexperienced pilots, led by a few veterans, up against mostly experienced allied pilots.

A lot of those low time Luftwaffe pilots probably weren't capable of flying their aircraft on the ragged edge of it's flight envelope.

Bodenplatte was mostly a low altitude slugfest. Low altitude, hard turns. and low time pilots is a combination that kills a lot of people in general aviation even today.


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## swampyankee (Feb 22, 2019)

Zipper730 said:


> And this gives pounds of thrust?



This is the formula for efficiency; airspeed and power could be known, thrust would be solved for

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## CORSNING (Feb 22, 2019)

Elvis,
I do not know what site the 180 deg./7 sec. for the Buffalo was posted on, but that
is the number for the Findland's B-239. This figure was for a speed of 349 km/hr at
2,100 m.
The following information is from Russian tests for a sustained 360 deg. turn at 1,000m.

Bf 109F-0 18 sec.
Bf 109G-2 20L/21.5R sec.
Hurricane IIb 20.5 sec.
Spitfire F. Mk. IX 17.5 sec.
Mustang I 23 sec.
B-239 15.8 sec./360 deg. @ 4,000 m.

I have put together 108 different models of A/C at 1000 m. and 77 different models of
aircraft at 4,000 m. The figures from 1,000 m. come from a few different sources mostly
from the Russian, French and Finish test. The figures I have at 4,000 m. come from Erik
Pilawlkii's aircraft compared book and are labelled, observed. Sorry I do not have time
to list them all at this time (to work at 5:00 a.m. you know). When I finally have a place
on a site to post all my aircraft performance material, I will make a special section for
these figures and post each with the perspective A/C models as I post.

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## Elvis (Feb 22, 2019)

Thank you, Corsning. I was starting to think those nice young men in their clean white coats were coming to take me away ()
I think you're citing a different test, though. It would make sense for a variety of tests to be done, probably on different occasions, too.
I'm sure I read that the test I'm thinking of was a U-turn (180 degrees) at 2000 metres.
The aggravating part is no one believes you until you can post something to back up your claim.....workin' on it.


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## Shortround6 (Feb 22, 2019)

Elvis said:


> The aggravating part is no one believes you until you can post something to back up your claim.....workin' on it.




It is not that I don't believe you read it, it is just so far off from the other aircraft that it boggles the mind. 
See Cornsings figures. 2/3s of the time needed by an Allison Mustang is at least believable (not that the Mustang is the gold standard) and somewhat quicker most everything else.

It is when you get to 1/3 of the time needed by most of the other aircraft that things get really strange (the maneuverability of a UFO) 

I have sure run across any number of misprints not only in books but in government manuals or government test results, some times you can guess what the number should be based on the trend,( numbers on either side).


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## Elvis (Feb 23, 2019)

...and yet, Corsning quoted it right in the beginning of his post....


> I do not know what site the 180 deg./7 sec. for the Buffalo was posted on, but that
> is the number for the Findland's B-239. This figure was for a speed of 349 km/hr at
> 2,100 m.


Mind boggling as it may seem, there you go.
...and btw, Corsning, the B-239 IS the Brewster Buffalo. It's my understanding that "B-239" was actually Brewster's model/catalogue number for that particular airplane. The US Navy designated it F2A-1. I think the British came up with the name, as they were in the habit of using model names, rather than letter/number sequences.

Elvis


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## CORSNING (Feb 23, 2019)

Elvis said:


> The aggravating part is no one believes you until you can post something to back up your claim.....workin' on it.



Elvis,
It is very important to have reputable reference material to back your statements if possible. 
That immediately takes a great deal of doubt out of your statement and gives some credence
to it. 
As I have mentioned from time to time I had posted a lot of WW2 fighter information on another
forum before it went defunct. I tried very hard to make sure I listed all sources for the information
I posted so that the reader could make up his own mind the validity of my posts. If everyone just
posted their beliefs or partial facts from their memory we would not be able to collaborate the
correct information to find the truth, or as close to the truth as we can.


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## CORSNING (Feb 23, 2019)

[QUOTE="Elvis, post: 1463014, member: 14526

Mind boggling as it may seem, there you go.
...and btw, Corsning, the B-239 IS the Brewster Buffalo.

*I wouldn't be too sure about that. I believe the Finns referred to it as The Brewster. .........
I will now request the knowledge of the other members of this site to correct me if needed.*

It's my understanding that "B-239" was actually Brewster's model/catalogue number for that particular airplane. The US Navy designated it F2A-1. I think the British came up with the name, as they were in the habit of using model names, rather than letter/number sequences.

*That is correct.*


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## Elvis (Feb 23, 2019)

I used to have the story on the Buff (Aviation History, Nov.1996).
The Finns got the Buff because the salesmen at Brewster convinced the US Navy to invest in the new upgrade to the Buffalo, the F2A-2, just after they had bought the F2A-1.
So all the planes were pulled and replaced with the "latest and greatest" version.
Just so happened Finland needed to upgrade their air force due to a skirmish they were having with Russia over 50 acres of land each said belonged to them.
Brewster not only gave them the planes that had been in service with the US Navy, they also boxed up all B-239's that had been under construction and various parts that had yet to be assembled.
The only change Brewster made to that version was that they equipped them with an older style antenna, an older style gunsight and an _international_ version of the R-1820 the plane used while in US Navy service (I wanna say it was the "G-205", but don't quote me).
Finland successfully used the plane for about two years. after which they were replaced with Bf-109's (although Finland was considered "neutral" during the war, they had a friendly alliance with Germany. In fact, it was the German's who guarded the port that the B-239's were originally brought in to).
In the end, both sides called a truce.
Finland annexed the 50 acres of land to Russia and in trade, the Germans stationed in Finland would have to leave, allowing the Russians use of that Port, unmolested (because it fell within the area of land that the Russians were after).
HOWEVER, the Russians were only allowed the use of that land (and the port) that was annexed to them. Thus, no "invasion" of Finland.
I think once that was all agreed to, the Finns bowed out of WWII and returned to neutrality.

Elvis


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## Elvis (Feb 23, 2019)

CORSNING said:


> Elvis,
> It is very important to have reputable reference material to back your statements if possible.
> That immediately takes a great deal of doubt out of your statement and gives some credence
> to it.
> ...


I understand what you're saying and it makes perfect sense.
I wasn't asking you to take me on my word alone, I was only stating how aggravating it is to know the information is out there and I can't find it to cite.
I kinda feel like the sane guy who was mistakenly placed in the insane asylum and all records of the court proceeding showing my sanity have disappeared. 

Elvis

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## CORSNING (Feb 23, 2019)

Elvis said:


> I was only stating how aggravating it is to know the information is out there and I can't find it to cite.
> I kinda feel like the sane guy who was mistakenly placed in the insane asylum and all records of the court proceeding showing my sanity have disappeared.
> 
> *I have felt that feeling many times my brother. You just have to take a deep breath, spend the time
> ...

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## eagledad (Feb 23, 2019)

Corsing and Elvis

Attached is a file of turn times for various fighters. The data was provided by members either Juha or Jukka (I think) I do not want to slight the indivdual(s) that provided the data and comments.

FYI

Eagledad

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## Shortround6 (Feb 23, 2019)

Elvis said:


> I used to have the story on the Buff (Aviation History, Nov.1996).
> The Finns got the Buff because the salesmen at Brewster convinced the US Navy to invest in the new upgrade to the Buffalo, the F2A-2, just after they had bought the F2A-1.
> So all the planes were pulled and replaced with the "latest and greatest" version.
> Just so happened Finland needed to upgrade their air force due to a skirmish they were having with Russia over 50 acres of land each said belonged to them.
> ...


That is not quite how it is laid out in AHT but the truth maybe somewhere between the two accounts?

The Navy had placed an order for 54 F2A-1s on June 11 *1938.*

On march 22 19*39* the Navy orders the conversion of the XF2A-1 prototype to XF2A-2 standard (maybe the Brewster salesmen were wining and dining the Navy brass?) 

June 20th 1939 sees the first production F2A-1 rolled out and delivered.

July 1939 sees the work done on converting the XF2A-1 to XF2A-2 standard and fight tests start. 

August 1939 sees the British stick their oar in the water.

August 1939 also sees the Poland order 250 F2A type fighters. 

Dec *1939 *sees 11 F2A-1s having been accepted by the US Navy (Brewster delivering late as would become usual) 

the remainder of the 54 plane order (43 aircraft) are released to Finland using commercial engines. 9of the Navy planes are put into service with VF-3 aboard the Saratoga. 

Dec 1939 sees the Dutch place their first order and Jan sees the British reverse course and order 120 panes (later increased to 170) 

Brewster delivers 17 aircraft in jan 1940 and 27 in Feb and they are shipped to to Sweden where they are assembled and test flown by SAAB at Trollhatten. 

It took until April for all the 239s to reach Finland. 

Dutch and British aircraft take precedence over US Navy deliveries and it is not until *Sept of 1940* that deliveries of the replacement aircraft to the US Navy began. 

After 43/44 F2A-2 aircraft are built production changes back to the British 339E. 

The US Navy orders 108 F2A-3 in Jan *1941 *because Grumman is slow delivering F4Fs, _BUT _Brewster does manage to rework eight of the Navies F2A-1s to F2A-2 standard (they did not go to Finland?) in May of 1941. Production of the F2A-3s starts in June with first aircraft accepted in July 1941. Production will run into Dec 1941/Jan *1942 *at which point it switches to the Dutch 439 model but none are delivered before the Dutch East Indies fall. 

I have no idea which account in more correct (Germans guarded Swedish port? or planes where unloaded and assembled somewhere else?) 

I don't really want to play the 'my source is better than your source' game.

however. 





Caption (from wiki) says "LT John S. Thach tipped this F2A-1 onto its nose on Saratoga, March 1940. "

The engines used in the F2A-1 and the Finish planes were R-1820G series engines. Which are quite different than G-100s or G-200s (changed from aluminium crankcase to steel crankcase, etc) the last number (as in G5 or G 205) designates things like supercharger gear ratio or some other difference. And this is where it gets more than a little difficult to figure out who got what. 
Wright would put the letter "G" in front of the engine designation if the engine was fitted with a reduction gear as in GR-1820G2 and leave if off if the engine was direct drive, R-1820G2 for example. The Military didn't make that distinction in the basic designation but had more model numbers at the end as in R-1820-40, which is actually (I think?) a GR-1820-205A.

For the R-1820 (at least the early ones) it seems the last digit of "2" signifies a 7 : 1 ratio is used in the supercharger drive. the digit "3" signifies an 8.31 : 1 ratio and the digit "5" signifies a two speed supercharger with a low ratio of 7.14 : 1 and a high ratio of 10.0 : 1 

again please note that this is for the civil designation, no such simple code exists for the military engines.

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## Elvis (Feb 23, 2019)

Shortround,
Not saying your info is incorrect, but I never cited any dates, so what are you debating with all the *bold* dates?
Thanks for the reminder on the engine designations. I do believe now it was the R-1820-G5 (not G205) that went to Finland with the rest of the B-239's.
As far as I can remember, I have never found (or heard of anyone else finding), a source to prove that 8 F2A-1's were left with the Navy, so that picture speaks loads.
Thanks also for posting that. Interesting that 8 were left behind. Maybe an oversight?
As for the port that the B-239's landed at, that was a Finnish port that was run by the German's (apparently there with the Finn's blessing).
Interesting interaction there, too. German run port accepting a shipment from USA due to sendee being the Finns.
….truth is indeed, stranger than fiction.


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## CORSNING (Feb 25, 2019)

eagledad said:


> Corsing and Elvis
> 
> Attached is a file of turn times for various fighters. The data was provided by members either Juha or Jukka (I think) I do not want to slight the indivdual(s) that provided the data and comments.
> 
> ...



*Thank you Eagledad. Juha posted that list on this site some time ago and I added some of his
information to my list. I had done pretty much the same thing as Juha collecting from several
sources and putting them all together. Finding information for 4,000 m. was a plus. Juha should
be commended for his efforts.*

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## P-39 Expert (Mar 2, 2019)

eagledad said:


> Corsing and Elvis
> 
> Attached is a file of turn times for various fighters. The data was provided by members either Juha or Jukka (I think) I do not want to slight the indivdual(s) that provided the data and comments.
> 
> ...


Fascinating. The P-47 certainly didn't turn very well. Admittedly 1000m was not exactly it's wheelhouse.


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## CORSNING (Mar 2, 2019)

P-39 Expert said:


> Fascinating. The P-47 certainly didn't turn very well. Admittedly 1000m was not exactly it's wheelhouse.



It would be very interesting to know all the ww2 aircraft's turn times at 30,000 ft./9,000 m.
The story was a very different one up there for the P-47 and its beautiful R-2800 engine.


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## Zipper730 (Mar 27, 2019)

Shortround6 said:


> Please note the curve marked "angle of straight climb" which pretty much marks the line between slowing down/descending and being able to climb while turning.


Isn't that basically a level-turn? I'm amazed by how people can complicate such simple things to the point that it becomes incomprehensible.


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## Zipper730 (Mar 27, 2019)

swampyankee said:


> Efficiency is defined as useful work out divided by energy in. For a propeller, that would be airspeed (in feet per second) times thrust (in pounds) divided by (horsepower multiplied by 550) or, equivalently, airspeed (in meters per second) times thrust (in newtons) divided by power (in watts).


Would this mean that 80% of the theoretical maximum power ends up emerging as actually power/force/thrust?


> This is the formula for efficiency; airspeed and power could be known, thrust would be solved for


Okay... let's start at the basics: I have a bunch of data from WWII Aircraft Performance on the Hawker Hurricane Mk.I & II's

In some cases, there are pieces of data that's missing: I'm trying to fill in the gaps to the best of my ability to determine how much thrust is being produced overall. Apparently I need to know horsepower in some cases, the speed in other cases (there are gaps in the data). I know the propeller diameter in all reference cases. 

I've been told speed can be graphed pretty reasonably in a linear fashion -- not sure if that's true, but if I provide the data -- can somebody help me fill out the gaps?


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## Zipper730 (Jul 2, 2019)

I was looking at .doc by 
E
 eagledad
, about turn-rates measured by the USSR in WWII. Does anybody know what speed these turns were entered at? Some cases seem to indicate a turn-radius, so that's not too hard; others have no indicated radius, which makes determination of speed impossible.

BTW: 

 BiffF15

X
 XBe02Drvr
Would the tightest rate of turn be at the corner-velocity?


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## XBe02Drvr (Jul 2, 2019)

Zipper730 said:


> BTW:
> 
> BiffF15
> 
> ...


Yes. It's all explained here:
Corner Speed
Cheers,
Wes


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## Zipper730 (Jul 2, 2019)

XBe02Drvr said:


> Yes. It's all explained here:
> Corner Speed


Okay, so as an estimate, you'd use compute power-on stall speed * square root of g-load right?


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## XBe02Drvr (Jul 2, 2019)

Zipper730 said:


> Okay, so as an estimate, you'd use compute power-on stall speed * square root of g-load right?


Don't ask me. Read the reference in its entirety, and if that's not good enough, google corner velocity. There's all kinds of stuff out there for you to find, so go find it instead of trying to get everybody to spoon feed you. If what you find raises questions, THEN ask the x-spurts.
Cheers,
Wes


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## Zipper730 (Jul 2, 2019)

XBe02Drvr said:


> Don't ask me.


Don't worry, I found the answer on another page on this site. It turns out, I asked this before, but forgot about it. You were actually the person who answered -- turns out power-on was not the speed figure to use, so I guess I'll just compute with power-off.


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## Zipper730 (Jan 7, 2020)

DarrenW said:


> Dean did some calculating of his own regarding the turn_ radius_ of various US fighters in _America's Hundred Thousand_


These numbers don't look right, now I could be wrong: I'm looking at stall speed x square root of g-load, and the P-61B's 1g stall speed @ 27000 lb. is 106 mph power off clean, flaps down is 88-89 mph if these figures are right, and I put a speed of 97-1/3 to 100.2 as a maneuvering flap setting if it even had one.





I get the following for 3g stall

183.6 mph flaps-up, power-off
153.6 mph flaps-down, power-off
168.6 - 173.6 mph flaps part-down, power off
The square root of 3 is 1.732050807568877

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## Zipper730 (Jan 9, 2020)

There's another flight manual on the P-61, and while there are slight variations in the stall speed, they're fairly close.


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## Elvis (Jan 10, 2020)

swampyankee said:


> Efficiency is defined as useful work out divided by energy in. For a propeller, that would be airspeed (in feet per second) times thrust (in pounds) divided by (horsepower multiplied by 550) or, equivalently, airspeed (in meters per second) times thrust (in newtons) divided by power (in watts).


Sorry to resurrect this part of the thread, but I'm curious....why are you multiplying HP by 550? What does 550 represent?
Thanks in advance.

Elvis


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## XBe02Drvr (Jan 10, 2020)

Elvis said:


> Sorry to resurrect this part of the thread, but I'm curious....why are you multiplying HP by 550? What does 550 represent?
> Thanks in advance.
> 
> Elvis


550 foot-pounds was how much work James Watt originally calculated one standard issue horse could accomplish in one point zero measured seconds.
Doesn't anybody teach history of technology anymore?
Cheers,
Wes

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## pbehn (Jan 10, 2020)

XBe02Drvr said:


> 550 foot-pounds was how much work James Watt originally calculated one standard issue horse could accomplish in one point zero measured seconds.
> Cheers,
> Wes


It was a Scottish steam horse.


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## swampyankee (Jan 10, 2020)

...and Watt was performing marketing. Horses are about 50% more powerful than that.


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## pbehn (Jan 10, 2020)

swampyankee said:


> ...and Watt was performing marketing. Horses are about 50% more powerful than that.


I think it was just a number that allowed him to make a fortune by the improvement in efficiency of steam engines as I remember.


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## Elvis (Jan 10, 2020)

XBe02Drvr said:


> 550 foot-pounds was how much work James Watt originally calculated one standard issue horse could accomplish in one point zero measured seconds.
> Doesn't anybody teach history of technology anymore?
> Cheers,
> Wes


But the formula already has you plugging HP in as a known source, so why are you calculating it again?


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## XBe02Drvr (Jan 11, 2020)

Elvis said:


> But the formula already has you plugging HP in as a known source, so why are you calculating it again?


He asked what the significance of 550 foot-pounds was. I wasn't calculating anything, just answering his question.


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## Zipper730 (Jan 12, 2020)

Since the figures for the P-61 were inaccurate, I've started looking at the other figures.

The F4F-3's stall speed was

74.2 mph @ 6895 lb
73.7 mph @ 6763 lb (80% fuel)
72.5 mph @ 6565 lb (50% fuel)
Which would yield a 3g stall of

128.9 @ 6895 lb.
127.7 @ 6763 lb.
125.6 @ 6565 lb.
Though there might be other variables at work, if I was to scale the stall figures up to the FM-2's weight, I would get the following

1G Stall: 77.2 mph @ 7420 lb.
3G Stall: 133.7 mph @ 7420 lb.
I guess up to this point, nobody had access to all the data, or was anal enough to compute it all out.


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## Elvis (Jan 12, 2020)

XBe02Drvr said:


> He asked what the significance of 550 foot-pounds was. I wasn't calculating anything, just answering his question.


...and that's another question....WHY are you commenting on this at all?
I was asking Swampyankee something specific about something specific that they posted.
It had nothing to do with you at all.


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## Elvis (Jan 12, 2020)

...and now that that got all mucked up, I'll ask again....ATTENTION: *SWAMPYANKEE*...



swampyankee said:


> Efficiency is defined as useful work out divided by energy in. For a propeller, that would be airspeed (in feet per second) times thrust (in pounds) divided by (horsepower multiplied by 550) or, equivalently, airspeed (in meters per second) times thrust (in newtons) divided by power (in watts).


Sorry to resurrect this part of the thread, but I'm curious....why are you multiplying HP by 550? What does 550 represent?
Thanks in advance.

Elvis


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## DerAdlerIstGelandet (Jan 12, 2020)

Relax everyone...

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## swampyankee (Jan 12, 2020)

Elvis said:


> ...and now that that got all mucked up, I'll ask again....ATTENTION: *SWAMPYANKEE*...
> 
> 
> Sorry to resurrect this part of the thread, but I'm curious....why are you multiplying HP by 550? What does 550 represent?
> ...




One horsepower is 550 ft-lbf (a unit of energy) per second. Power is energy per unit time. Confusingly, torque is also measured in ft-lbf (I know; some people use lbf-ft), but the two are fundamentally different quantities, like speed and hair color.

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## XBe02Drvr (Jan 12, 2020)

Elvis said:


> Sorry to resurrect this part of the thread, but I'm curious....why are you multiplying HP by 550? *What does 550 represent?*





Elvis said:


> ...and that's another question....WHY are you commenting on this at all?
> It had nothing to do with you at all.


Well, excuse me for living! You asked a question, I offered an answer. I didn't realize I was intruding on a private conversation on this *public* forum. Excuse me all to hell. I'll don my dunce cap and go sit in the corner.
Cheers,
Wes 😭


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## DerAdlerIstGelandet (Jan 12, 2020)

Relax everyone...

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## Elvis (Jan 12, 2020)

swampyankee said:


> One horsepower is 550 ft-lbf (a unit of energy) per second. Power is energy per unit time. Confusingly, torque is also measured in ft-lbf (I know; some people use lbf-ft), but the two are fundamentally different quantities, like speed and hair color.


Thank you for taking the time to explain that.
I think I'll look into this a little further.

Elvis


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## Laurelix (Jan 13, 2020)

sustained 360 horizontal turn
Ki-43-I - 12.5-13 sec
A6M2 - 13-14 sec
A6M3 - 14-15 sec
A7M2 - 14-15 sec
A6M5 - 15-16 sec
Ki-61-I - 16 sec
Ki-84 - 17 sec
Ki-100 - 17 sec
N1K2-J - 17 sec
BF-109E - 17 sec
P-39N - 17-18 sec
Yak-9 - 18 sec
Yak-3 - 18 sec
Ki-44-II - 18 sec
J2M3 - 18 sec
P-40F - 18 sec
Yak-9U - 18-19 sec
BF-109F-4 - 19 sec
BF-109G-10 - 19 sec
La-7 - 19 sec
F4U-4 - 20 sec
La-9 - 20-21 sec
F4U-1 - 21 sec
F6F-5 - 21-22 sec
P-51D (67Hg) - 22 sec
P-38J - 22 sec
FW-190A-5 - 23 sec
Ki-94-II - 23 sec
P-47N - 26 sec

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## Elvis (Jan 14, 2020)

What source are you quoting?


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## P-39 Expert (Jan 16, 2020)

Interesting. P-39N was the tightest turning plane not made in Japan (or an obsolete Bf109E).


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## tyrodtom (Jan 16, 2020)

Laurelix said:


> sustained 360 horizontal turn
> Ki-43-I - 12.5-13 sec
> A6M2 - 13-14 sec
> A6M3 - 14-15 sec
> ...



Several important aircraft not on that list, F4F, P-36, early model Mustangs, no Spitfires or hurricanes at all.


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## Zipper730 (Jan 25, 2020)

We should also try and find the stall speeds whenever possible as that will give the speed at which it becomes possible to pull a given g-load. That said, some airplanes are more sluggish than others and will take longer to pile on the g-load, so, it's just a start...


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## pbehn (Jan 25, 2020)

Zipper730 said:


> We should also try and find the stall speeds whenever possible as that will give the speed at which it becomes possible to pull a given g-load. That said, some airplanes are more sluggish than others and will take longer to pile on the g-load, so, it's just a start...


Which stall speed? At which altitude? An aircraft can stall out on full power while pulling many "G". Thats where these "spanwise lift distribution" discussions are important. A plane that is completely benign coming in to land obviously at 1 G can stall with no warning at all its power on limit.


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## XBe02Drvr (Jan 25, 2020)

Zipper730 said:


> That said, some airplanes are more sluggish than others and will take longer to pile on the g-load, so, it's just a start...


Any plane that needs to pile on the G load to do its job, such as fighters, fighter-bombers, attack planes, etc, while it may be sluggish in roll, isn't likely to be sluggish in pitch, as that's the working parameter in all combat maneuvering. A plane that reacts slowly in pitch is dogmeat, so elevator response and stick force gradient (the thing that will most likely impede pitch response) are critical design parameters.
Cheers,
Wes


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## XBe02Drvr (Jan 26, 2020)

pbehn said:


> A plane that is completely benign coming in to land obviously at 1 G can stall with no warning at all its power on limit.


What do you mean by "its power on limit"? "on limited power"? Or "power on its limits"? In other words, "reduced throttle" or "full throttle"? In either case a plane with no wing twist, so the entire wing stalls at once, can hardly be called benign. And if it has wing twist so the wing stalls progressively, root to tip, it's pretty hard to stall it without causing warning buffeting, especially at approach speeds and configurations.
One thing I don't get is why AOA indicators have been so slow to take hold in the civilian world. USN and USMC have been using them to great effect since WWII, and I'm convinced they are a superior way to fly safely. Our club T34 had an approach indexer, which is a rudimentary AOA indicator, and I was taught to use it from my first flight in the bird. Oddly enough, the FAA, when they issued the civil type certificate for the B Model T34 specified that the approach indexer had to be disabled and its indicator masked over. When the club took delivery of their bird, the base CO (who had instructed in Teenie Weenies earlier in his career), came over for a look-see and made the club's mechanic unmask the indicator and re-activate the system. "Best damn safety device on the whole plane. If the FAA gives you any flak over it, send them to me!" The Feds did and the club did, and that's the last anybody ever heard of it. And the legend still lived on when I joined the club several years later.
Cheers,
Wes


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## Laurelix (Jan 26, 2020)

*Calculating the Stall Speed is easy.*
Here is the formula:








V = Stall Speed (Metres Per Second)
L = Lift Force (Newton’s)
CL = Wing Lift Coefficient
P = Air Density (1.225kg/m3 at sea level)
A = Wing Area (Metres Squared)

On this website it will calculate the stall speed for you
Airplane Aircraft Wing Lift Design Equations Formulas Calculator - Velocity

-

Kurfürst - R.A.E. - Messerschmitt Me.109 Handling and Manoeuvrability Tests
Here are the British stall speed tests to determine the CL_Max (Wing Lift Coefficient) for BF-109E







BF-109E
Loaded Weight = 5580lbs / 2531kg
Lift Force = 2531kg x gravity (9.81) 
= 24829 Newtons 
Wing Area = 174sq ft / 16.17m2
Air Density at Sea Level = 1.225kg/m3 
CL_Max = 1.4 (no flaps)







V = 42.31m/s stall speed which is 152km/h 

The UK source states 95.5mph stall speed which is 154km/h. The 2km/h difference probably comes from the weight being round up.

Planes with laminar wings have about 1.3-1.33 CL_Max. These wings produce less lift, but also less drag which means these wings give a plane higher top speed whilst sacrificing manoeuvrability

Planes with Normal Wings have about 1.4-1.5 CL_Max
All BF-109’s and FW-190’s and Ta’s have 1.4-1.41 CL. Ki-61/100 has 1.44 CL, Ki-84 has 1.46 CL. P-47’s have 1.5 CL, F6F and F4U also have like 1.4-1.41 CL

The lower the stall speed, the better the initial turn. Then it comes down to how well the plane can maintain energy in a sustained turn to determine the overall sustained turn time. Power to weight ratio is good determining factor but the drag of the plane etc also plays a role.

if you want to know the stall speed of a plane whilst it’s using flaps, you have to add the flap area to the total wing area and use the correct CL_Max. In this case, BF-109E wing lift coefficient using flaps is 1.9. You’ll also have to add the flap area on top of the 16.17m2 wing area in the equation

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## Zipper730 (Jan 26, 2020)

pbehn said:


> Which stall speed?


Generally, I tend to use the power-off stall speed as a guideline.


> At which altitude?


That has to do with mach effects on airspeed? I have no idea how to compute that out, though I'm curious if there are any form of correction factor to come up with something remotely accurate, reasonably speaking.


> An aircraft can stall out on full power while pulling many "G". Thats where these "spanwise lift distribution" discussions are important. A plane that is completely benign coming in to land obviously at 1 G can stall with no warning at all its power on limit.


Accelerated stall piles on more loads on the wing, wing twists start to take hold, you have airflow asymmetries that are involved (turns), and things happen more abruptly. Snap-rolls are awesome to watch -- a rapid pitch up and jerky but fast roll. It also dumps speed so you can force overshoots with it..



XBe02Drvr said:


> Any plane that needs to pile on the G load to do its job, such as fighters, fighter-bombers, attack planes, etc, while it may be sluggish in roll, isn't likely to be sluggish in pitch, as that's the working parameter in all combat maneuvering.


Yet attack planes often _do_ seem to require more pounds per-g than do fighters, and are often trimmed nose-up for dive-recovery. That said, I would not suspect that they were _extremely_ sluggish in terms of pitch -- just moreso than fighters.


> What do you mean by "its power on limit"?


I guess power on stall?


> One thing I don't get is why AOA indicators have been so slow to take hold in the civilian world.


Actually, that is good point: When did they first appear in the commercial aircraft industry?



Laurelix said:


> *Calculating the Stall Speed is easy.*
> Here is the formula:
> 
> 
> ...


Just out of curiosity

Newtons is 1/(kg*m/s^2), correct?
Coefficient of lift is a ratio of the lift to dynamic force right?
What would you use for imperial measurements in terms of lift-force and air-density? I can enter either one, but I figure it's useful to be able to use either conversion factor.



> On this website it will calculate the stall speed for you
> Airplane Aircraft Wing Lift Design Equations Formulas Calculator - Velocity


Cool


> Kurfürst - R.A.E. - Messerschmitt Me.109 Handling and Manoeuvrability Tests
> Here are the British stall speed tests to determine the CL_Max (Wing Lift Coefficient) for BF-109E


So they plugged in all the other figures to get the C/L?


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## CORSNING (Jan 27, 2020)

Laurelix said:


> sustained 360 horizontal turn
> A7M2 - 14-15 sec
> Ki-84 - 17 sec
> Ki-100 - 17 sec
> ...



Laurelix,
I have a few questions about the times you have posted for the above aircraft sir.
1. What is your source for all your posted times?
2. At what altitude were these times recorded?
3. Are any of the aircraft take-off weights listed in your sources?
I have a listing of all the Soviet turn times recorded at 1,000 m. and a list of about 85 A/C turn times at 4,000 m.
which according to Erik Pilawskii these are observed tests. The above aircraft are not listed for the sourced I
have and I am very interested in adding them if the source is solid.

Thank you in advance, Jeff


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## Laurelix (Jan 27, 2020)

CORSNING said:


> Laurelix,
> I have a few questions about the times you have posted for the above aircraft sir.
> 1. What is your source for all your posted times?
> 2. At what altitude were these times recorded?
> ...


All calculated. But it matches sources. For example I calculated 19 sec for La-7 and that’s exactly what the Russian tests concluded.


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## CORSNING (Jan 27, 2020)

Laurelix said:


> sustained 360 horizontal turn
> 
> *The following is what I have on file for these aircraft. The 4,000 m figures are from
> Erik Pilawskii's book Fighter Aircraft of WW2, A Comparative Study. He states in
> ...


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## Laurelix (Jan 28, 2020)

Mind you Yak-9U tests probably shown 19.5 because in the beggining it didn’t have fuel injection and was limited to 1500hp but later had 1650hp which would of given it 18-19 sec

as for BF-109E test, they must of screwed something up really bad during the test to get 23-26 sec because the aircraft was capable to turn with the spitfire initially when it deployed its flaps. This wouldn’t be possible if it had 23-26 turn time. You’d need the BF-109E to have like 1.02 CL_Max

the British themselves tested the stall which was 154km/h (1.4 CL) compared to the 163km/h on Yak-3. So BF-109E has lower stall speed than Yak-3 and with 1160hp for 2530kg weight which gives slightly worse power to weight ratio than yak-3. With 9-11km/h lower stall speed the BF-109E should easily beat Yak-3 in a turn fight. Now if Yak-3 has 17-18 sec turn time, how can BF-109E have 23-26 sec?

just goes to show how flawed turn rate tests can be and sometimes it’s just better to trust the maths and the physics

also the P-40F turn rate of 18.5 sec at 8500m is complete nonsense do you even know how lack luster it’s engine is at that altitude to sustain a turn, never mind the extremely low air density

P-40F has 3855kg loaded weight, 21.93m2 wing area, 850 horsepower at 9000m.
The air density at 8500m is 0.4951kg/m3.
P-40F has 1.41 CL max wing lift.

At 8500m the P-40F would have 253km/h stall speed (imagine how huge the turn radius is)
On top of that the engine is only spewing out 850 horsepower trying to support a 3855kg of weight... getting 18.5 sec sustained turn in these conditions is nothing short of bullshit

I don’t know about you but my turn times make far more sense and look far more realistic than these actual tests than have so many other factors that could effect it and cause the test to be ruined and then getting the wrong values.

at sea level with 1.225kg/m3 air density the P-40F would have 161km/h stall speed and at sea level it’s engine can produce 1420 horsepower. BF-109E has lower stall speed and FAR BETTER power to weight ratio to sustain turns than P-40F.


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## CORSNING (Jan 28, 2020)

OK then, I pulled the P-40F @ 28,000 ft. until I can locate and study the
report closely. I believe 18.5 is the turning ability for this aircraft. To
compare, the Spitfire LF Mk.IX's turn time was 18.5/1,000 & 4,000 m.

Since you mentioned it, seems to me the 23-26 seconds for the Bf.109E-3
was measured with some trouble with the *slats *opening...? I believe the 18.92
and 20.2 times were correct. 17.0 seconds would put it on par with
the Yak-9, and that, it was not.

*Nope, I found the Bf.109E-3 report. The supercharger wasn't functioning
correctly.*


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## Laurelix (Jan 28, 2020)

CORSNING said:


> OK then, I pulled the P-40F @ 28,000 ft. until I can locate and study the
> report closely. I believe 18.5 is the turning ability for this aircraft. To
> compare, the Spitfire LF Mk.IX's turn time was 18.5/1,000 & 4,000 m.
> 
> ...


That’s only what you think.

eighter way a plane with lower stall speed that can sustain it better will have superior sustained turn than a plane with higher stall speed (bigger turn radius) and worse sustainability. In this case BF-109E is on par in turn but it’s not as fast as Yak-9. BF-109F/G obviously turned worse


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## CORSNING (Jan 28, 2020)

Laurelix said:


> That’s only what you think.
> 
> *Yep, me and all the guys who recorded the actual testing of the aircraft*.


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## Laurelix (Jan 28, 2020)

According to that book, Yak-9 is turning better than a spitfire LF IX?
I can tell you right now it’s sustained turn is like 16 sec, not 18.5 sec
Otherwise La-7 turns as good as spitfire LF IX which too is nonsensical


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## CORSNING (Jan 28, 2020)

The 18.5 turn for the La-7 was for a late 1945 version. The earlier
La-7 was tested at 20-21/1,000 m & 19.5/4,000 m.
I have nine tests for Spitfires from Mk.I to Mk.IX. None of these
tests recorded less than 17 seconds ability. However, the 17 seconds
for the Mk.I & II were at 4,000 m.
I remember reading about a fighter competition in Italy where Soviet
and Allied pilots flew their fighter aircraft against each other in mock 
combat. One of the British pilots claimed that the interior of the Yak-9 
was very crude but none of the aircraft there were able to stay with the
Yak-9 through maneuvers. The Yak-9 in question was the Yak-9DD, 
perhaps the least maneuverable of the series.


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## Zipper730 (Mar 20, 2020)

I think it's about time we bring this thread back to life.


BTW: Notes to self, to determine newtons in regard to lift, use mass in kg * 9.80665; propulsive efficiency is the percentage of HP that gets turned into thrust


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## Zipper730 (May 2, 2020)

This comes from a multi series article on Greg's Planes and Automobiles about the P-47, and an image (to be added shortly) which covers the Me-262 (and sustained turn-rates with airspeeds).



This seems to cover a bit, though I'm not sure I get everything here (the propeller efficiency thing I kind of didn't quote grasp). There were links below, that I think would be useful to everybody here, and probably me when my mind works better as things start coming online. I did get up at around 7 PM, so today might not be my day to do this.


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## Zipper730 (Jun 5, 2020)

L
 Laurelix97
, 

 swampyankee


The coefficient lift figures which you posted earlier on the Ki-84 (CL Max w/ Flaps 0: 1.46; w/ Flaps 15: 1.7; w/ Flaps 30: 1.92): I'm curious if theres any online sources that have reliable CL figures for aircraft seen in WWII?

Furthermore, when it comes to altitude: Would you simply input a different air-density that correlates to the different altitude and air-temperature?

As for computing power to weight: Does that produce accurate sustained turning performance? After all, with different propellers producing different thrust, different thrust coming out of the exhaust system at different altitudes, and tip-velocities nearing the speed of sound at high speeds seem all to be something that would affect overall thrust.

Regarding the formula FPS * (550*HP). For a 2000 horsepower engine, I end up with 1,100,000 foot/pounds. I'm not sure how that can be used to provide overall engine thrust, as I've never heard thrust figures that high for any propeller engine.


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## Laurelix (Jun 20, 2020)

someone copied and pasted Ki-84 manual details into the comment section here.
I happen to come across it and realised that it included wing lift coefficient of the wings.
Nakajima Ki-84 Hayate / FRANK - fighter

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## Zipper730 (Jun 20, 2020)

Was there any changes made to the Ki-84 wing


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## Laurelix (Jun 22, 2020)

Zipper730 said:


> Was there any changes made to the Ki-84 wing


all Ki-84's used the same wing.

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## Zipper730 (Jun 9, 2021)

I honestly should have bookmarked this particular page.


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## GregP (Jun 21, 2021)

Reference post #124.

The A6M was NOT a weak airplane and its wings did not break off easily. U.S. fighters were stressed to 8 g's with a safety factor of 0.5, for an ultimate load factor of 12 g's. The A6M was stressed to 6 g's with a safety factor of 1.0, for an ultimate load factor of 12 g's.

This means that the U.S. fighter could sustain 8 g's many times with no damage. If loaded to over 8 g's, the structure would take it, but could be damaged beyond continued use. You'd expect structural failure at anything over 12 g's. For the A6M, it could sustain 6 g's many times without failure but could be damaged at loads over 6 g's. Again, you'd expect structural failure at anything over 12 g's.

The A6M was not and IS not flimsy, weak, or poorly made. It is a good, solid airplane that, like all other airplanes, has limitations. The A6M was designed to excel at dogfighting at speeds of 180 - 290 mph, and it did that job VERY well. Since the designer didn't have a 1,500+ hp engine to work with, he had to make design choices to get good performance. In the case of the A6M, that meant lighter structure and no armor, resulting in a plane that was good at dishing out punishment, but not so good at taking it. That was acceptable to the Japanese military.

When the same designer had a more powerful engine, he came up with the J2M Raiden. It was a match or better for most late-war Allied fighters in ceiling, armament, climb, and maneuverability. It was was slightly slower than most late-war U.S. fighters, but could still catch a B-29, something that many other Japanese fighters could not do. They just never got to built very many of them.

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## GregP (Jun 22, 2021)

So, you believe that post above about the CL and the flight test report translation?

It MIGHT be true, but I have seen too many people with an agenda make false claims to believe it without seeing the reference. The reference he translated might also be bogus and I can't find it. Maybe not, but maybe. I can't say for sure. So, it falls into hearsay, for me rather than reference values. One post makes it seem like Ron is Shinpachi in this forum. If so, I have more faith in the text than before.

I found an English language flight test dated Nov 46 and found no CL or empty weight.

Hi Shinpachi, was that post from you?


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## Zipper730 (Jun 28, 2021)

Okay, I was looking at the figures cited from America's Hundred Thousand, which I've put into an Excel sheet (then turned that into a screen-cap)







The red stuff was things I either know are wrong or strongly suspect, the gray item was something I was just unsure of: The P-61B's wing area is 662.36 square feet and, while I'm unsure the exact C/L for the P-51, I've heard some sources that listed numbers lower (1.5). I'm curious if anybody has more accurate data on the coefficient of lift figures for the aircraft in question since I have doubts as to the accuracy of the source.

The wing-area for the P-51 seems to vary a bit from 233 to 235.7 or so. I'm not sure why there are variations in this area.

Thanks


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## swampyankee (Jun 28, 2021)

Zipper730 said:


> Okay, I was looking at the figures cited from America's Hundred Thousand, which I've put into an Excel sheet (then turned that into a screen-cap)
> 
> View attachment 630207
> 
> ...


I'd be _very_ leery of all those posted lift coefficients. It's fairly rare for airfoils to get no-flaps lift coefficients quite that high except for some fairly special cases, like the high-lift Liebeck airfoils (which generally suck otherwise). See, for example, Abbot & von Doenhoff, _Summary of Airfoil Data_, Summary of Airfoil Data - NASA Technical Reports Server (NTRS)

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## XBe02Drvr (Jun 28, 2021)

Zipper730 said:


> The wing-area for the P-51 seems to vary a bit from 233 to 235.7 or so. I'm not sure why there are variations in this area.


At some point in P51 manufacture the wing leading edges were "cranked" forward at the root, adding a few square feet. IIRC, some earlier aircraft were updated to the later standard. It's all in Drgondog's book, _P51B, _a very good read.

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## Zipper730 (Jun 28, 2021)

XBe02Drvr said:


> At some point in P51 manufacture the wing leading edges were "cranked" forward at the root, adding a few square feet. IIRC, some earlier aircraft were updated to the later standard. It's all in Drgondog's book, _P51B, _a very good read.


This the book?

P-51B Mustang: North American's Bastard Stepchild that Saved the Eighth Air Force


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## XBe02Drvr (Jun 28, 2021)

Zipper730 said:


> This the book?
> 
> P-51B Mustang: North American's Bastard Stepchild that Saved the Eighth Air Force


Yup, that be the one.


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