WWII Rate of Turns

[Zipper730]

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.

1. Tightest turning circle period
2. Tightest turning circle under typical speeds, weights & altitudes
3. Most rapid degree per second rate of turn period
4. 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?

 

[pbehn]

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

 

[Zipper730]

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

 

[Ivan1GFP]

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.

 

[pbehn]

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.

 

[swampyankee]

One can define several types of "tight turns":

1. Maximum instantaneous turn rate.
   
2. Maximum sustained turn rate
3. Minimum sustained turn radius
4. 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.

 

[swampyankee]

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.

 

[Zipper730]

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...

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...

One can define several types of "tight turns":

1. Maximum instantaneous turn rate.
   
2. Maximum sustained turn rate
3. Minimum sustained turn radius
4. Minimum instantaneous turn radius

1. 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.

 

[Ivan1GFP]

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.

 

[swampyankee]

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...

• 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

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

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

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

1. 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.

Of course
I figured aspect-ratio would matter too
Would that be borne out in fact? I figure a fighter would just have to buzz the plane and knock it out of control.

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.

 

[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.

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?

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.

 

[DarrenW]

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!

 

[Shortround6]

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.

 

[pbehn]

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.

 

[Ivan1GFP]

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.

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.

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.

.....

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.

 

[windswords]

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

 

[Zipper730]

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...

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?

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...

 

[fubar57]

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

The FAA first used the G-Suit operationally in 1942

 

[Zipper730]

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...

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).

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...

 

[Glider]

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