Fighter Top speed timeline

[FLYBOYJ]

The Oscar 1 wasnt that slow!! it had the same max speed like the Zero 2.

I think you're confusing models -

Japan's Nakajima Ki-43 Hayabusa (peregrine falcon), "Oscar" - World War II Vehicles, Tanks, and Airplanes

The I and Ia had a top speed of just over 300 mph at altitude. The IIb had a top speed of 320 mph.

So Sea level speed was around 460km/h vs 475km/h of the P40C.
As higher the planes did fly as better the Ki-43-1 got, in comparison to the P40C. Due to the higher weight, smaler drag and higher engine power, the P40C always could outaccelerate the Oscar1, same like the Zero 2 in a shallow dive, while the initial acceleration was way better with the Japanese planes.

Agree to a point - I have to look up my references as to the P-40B/C sea level speeds

Since the allied pilots fast got aware of this, they just kept the speed up and avoided tight fights and they was happy not to have a 20mph slower airplane.

And they usually "sped away" in a dive which gave them way more than 20 mph. The Zero's VNE was 410 mph from what I remember. The P-40 was able to safely dive at speed in excess of 480 mph.

 

[FLYBOYJ]

Another "Oscar" site

WWII TECH: World War II History - Japanese Aircraft - Nakajima Ki-43 Hayabusa (Oscar)

The I and Ia were the first ones encountered. The IIa and IIb (which saw a great improvment) began to see service I believe in mid 1943.

 

[Vincenzo]

The Oscar 1 wasnt that slow!! it had the same max speed like the Zero 2.

So Sea level speed was around 460km/h vs 475km/h of the P40C.
As higher the planes did fly as better the Ki-43-1 got, in comparison to the P40C. Due to the higher weight, smaler drag and higher engine power, the P40C always could outaccelerate the Oscar1, same like the Zero 2 in a shallow dive, while the initial acceleration was way better with the Japanese planes.

Since the allied pilots fast got aware of this, they just kept the speed up and avoided tight fights and they was happy not to have a 20mph slower airplane.

On the speed of Oscar I (Type 1 model I) at FTH was slowest (15/20 mph) of Type 0 model 21 (idk if this is the zero 2), at SL they have near the same speed taht you indicated.
the Type 1 model II get evolution within time so started slowest of model 21 and ended fastest but this Type I timeline it's near to 0 model 22 (early '43)

 

[davparlr]

Thirdly maximum level speed is a funny thing. It is like the disparity between service ceiling and operational ceiling. Assuming you have not overloaded the airframe and can use the same angle of attack between weight changes, the maximum level speed is never affected by weight alone but and this is a very important but, if you make an aircraft heavier the time it takes to accelerate to your maximum level speed maybe too long to make it usable in service conditions.

This is strange. One cannot maintain the same angle of attack and airspeed and maintain level flight with a heavier load. Level flight means lift equals weight. Increase the weight and you must increase the lift. To do this at a constant speed, angle of attack must increase, increasing induced drag.

The only thing which limits maximum level speed is thrust to drag, not weight.

Drag is a function of lift required which is a function of weight. So drag is a function of weight, so, weight is a function of top speed.

So if you get a Spit, which can do say 360mph and then you make it heavier without increasing drag,

You cannot do this and maintain level flight.

the only reason it now does 350mph is because it takes too long to continue accelerating to 360mph under service conditions. By that I mean it works like this...

No. The reason it does 350 mph is because the engine thrust cannot overcome the added drag of the lift needed to carry the added weight.

Feller, that's how it works.

I am afraid it isn't. Now, aerodynamically, induced drag impact is reduced as airspeed increases. So, at high speed, airspeed impact of increased weight is generally not significant. A 2000 lb increase in weight of a P-51D impacts the top speed by about 7-8 mph, according to North American Aviation documents.


Here are a few comments, first the impact of top speed. In my mind top speed has two important components to combat, engaging and disengaging. Once maneuvering combat starts, top speed become irrelevant except for disengagement. Other factors become more important including turn rates, sustained turns, acceleration, climb rate, dive rates, etc. However, I believe that an actual 20 mph, not tested, not calculated, etc., is indeed a significant amount of airspeed advantage. A fighter, with a 20 mph overtake, one mile behind another fighter, will catch the chased fighter in three minutes. In addition, this speed advantage would help significantly to withdraw, say, when you run out of ammunition. As I have stated before, if you are on the highway at 70 mph and someone passes you at 90 mph, you would say "boy, that guys in a hurry". If I remember my T-38 days correctly, if one was to perform a formation rejoin with a 20 mph closure, he would find himself either wings level zooming under lead for a turning rejoin, or, throttles idle, speed brakes out, swapping leads in an in-trail rejoin (been there, done that). In either case, he would find himself being "politely" chewed out from one end to the other by the instructor in lead.

Now, for any two given aircraft, this 20 mph advantage is extremely hard to determine without side by side testing due to the variables previously discussed.

 

[FLYBOYJ]

Here are a few comments, first the impact of top speed. In my mind top speed has two important components to combat, engaging and disengaging. Once maneuvering combat starts, top speed become irrelevant except for disengagement. Other factors become more important including turn rates, sustained turns, acceleration, climb rate, dive rates, etc. However, I believe that an actual 20 mph, not tested, not calculated, etc., is indeed a significant amount of airspeed advantage. A fighter, with a 20 mph overtake, one mile behind another fighter, will catch the chased fighter in three minutes. In addition, this speed advantage would help significantly to withdraw, say, when you run out of ammunition. As I have stated before, if you are on the highway at 70 mph and someone passes you at 90 mph, you would say "boy, that guys in a hurry". If I remember my T-38 days correctly, if one was to perform a formation rejoin with a 20 mph closure, he would find himself either wings level zooming under lead for a turning rejoin, or, throttles idle, speed brakes out, swapping leads in an in-trail rejoin (been there, done that). In either case, he would find himself being "politely" chewed out from one end to the other by the instructor in lead.

Now, for any two given aircraft, this 20 mph advantage is extremely hard to determine without side by side testing due to the variables previously discussed.

Great post Dave - one also has to consider that during in that 3 minute chase you're probably at full power which in most aircraft would be limited for 5 minutes. Bump that scenerio to 2 or 3 miles and more than likely you're not going to be able to chase down the other aircraft without doing some damage to the engine.

As far as that 20 mph for disengagement - put 2 aircraft wintip to wingtip and one tries to disengage with that 20 mph advantage. Unless he can quickly accelerate to exploit that speed advantage, he's just setting him self up as a nice jucy target, that's the point I'm trying to make.

 

[davparlr]

Great post Dave - one also has to consider that during in that 3 minute chase you're probably at full power which in most aircraft would be limited for 5 minutes. Bump that scenerio to 2 or 3 miles and more than likely you're not going to be able to chase down the other aircraft without doing some damage to the engine.

At least you caught him with a couple of minutes of max power available to nail him.

As far as that 20 mph for disengagement - put 2 aircraft wintip to wingtip and one tries to disengage with that 20 mph advantage. Unless he can quickly accelerate to exploit that speed advantage, he's just setting him self up as a nice jucy target, that's the point I'm trying to make.

You certainly cannot outrun a bullet so you would have to have separation before you dashed off. Still better than being 20 mph slower!

It is interesting discussing what makes a great fighter, speed, climb, acceleration, armor, armament, etc etc. Every pilot says his plane is the best, but then he represents the ones that lived. The pilots that were killed never complain about their aircraft. And the pilot is a major part of the weapons system. Each aircraft has its on set of characteristics, the better ones had more better characteristics than the poorer ones. Expert pilots could utilize the good or avoid the bad characteristics of their aircraft to achieve advantages over the less expert pilots. The arguments will go on ad infinitum.

 

[FLYBOYJ]

You certainly cannot outrun a bullet so you would have to have separation before you dashed off. Still better than being 20 mph slower!

LOL - I can agree with that!

I think that's the angle missing here - Seperation. As you said, you're not going to out run a bullet, but put a mile or two behind you and I can see that 20 mph advantage working.

It is interesting discussing what makes a great fighter, speed, climb, acceleration, armor, armament, etc etc. Every pilot says his plane is the best, but then he represents the ones that lived. The pilots that were killed never complain about their aircraft. And the pilot is a major part of the weapons system. Each aircraft has its on set of characteristics, the better ones had more better characteristics than the poorer ones. Expert pilots could utilize the good or avoid the bad characteristics of their aircraft to achieve advantages over the less expert pilots. The arguments will go on ad infinitum.

BINGO!

 

[Knegel]

As i wrote many times here, maximum speed is not all, but for a less good turning and climb plane its all and everything(P40 vs Zero).
If the P40 would have been 20moh slower, its dive acceleration wouldnt have been as good as well.

With given power, the max velocity give a hint to the drag at high speed and thats a major factor when it comes to dive acceleration.

 

[vanir]

Knegel please excuse how repetitive this post is going to be, I am not being patronising or short with you, I simply find it awkward sometimes to speak clearly without overcomplicating myself, so I try to say something in many different ways so that it can be seen that from several approaches the same conclusion is self evident. I repeat myself only in trying to communicate most clearly, I apolegise ahead of time if I might seem offensive in any way here as it is not in any way my intention, my respects to you.

edit, since I just noticed Dave's post this applies to his as well, see bolded ahead.


Knegel as I understand it you've been talking about Vmo, not Vmax and we both seem to agree you're not talking about VNE or critical mach.

You seem to be missing the most basic description of the four primary aeronautical forces of lift, weight, thrust and drag and the secondary rule to get more lift, just go faster (I'll come back to this for Dave).

Here it is again. So long as you've maintained correct airframe balance installing your extra weight, being heavier doesn't mean you have to raise AoA. What it does, all it does is raises your wing loading. The only thing that means is you have to keep your minimum operating speeds higher, but even economy cruise is well above stall speeds at normal operating altitude (maximum altitudes will be reduced by higher wing loading).

You don't have to start pointing the nose up just because you raised wing loading. The 109G actually has less wing area than the Emil and more weight, but flies at the same AoA at normal speeds.

Drag is not increased when increasing loaded weight, so long as the airframe remains properly balanced and this weight isn't in external protrusions. Stall speeds increase though, so at very low speed you have to raise AoA or put your flaps down sooner, or land faster. It's only at low speeds.

The only time this isn't true is if you've exceeded the maximum wing loading on that airframe design by increasing weight too much for the wing area that you have.

The Messerschmitt has a higher wing loading than the Spit, and it doesn't run around at a higher AoA than the Spit. They both sit at something like 3-deg at cruise and neutral in the high speed condition (handled with elevator trim).

Everything I wrote about thrust, drag, torque and weight is physically sound.

I won't go venture into speed testing conventions and benchmarks as it would be a long conversation which would hijack the thread too much and isn't directly relevant to the point anymore than you said Vmax wasn't. I'm sure we both understand conventions vary between RAF, NACA and USN testing procedures, and then again by the time period (it's a hilarious story how they tested design limitations in the thirties, I'm surprised any test pilots survived, I mean seriously 12g pullouts at 5000 feet in an F3F those Navy guys were insane).


Dave, two things with your P-51 example. That fuselage tank imbalanced the aircraft, it was unstable until it emptied. There's also the point that with that wing there was already a situational stall issue on that model (though it handled well).
To save confusion with the Mustang, let's take this to a hypothetical extreme so aircraft type is superfluous. I add 5 tons to my P-51 but I put it directly over the centre of lift for perfect balance and it's a magical weight which has no external protrusion, so the only impact it has is on my wing loading. Which is now well and truly exceeded in terms of design limitations. But let's say I have a magical supercharger which gives me an extra 10000hp and 600% greater magical thrust. My stall speed might be 650km/h because of wing loading and my take off speed 700km/h but so long as I go fast enough to generate enough lift from the wing area I have, I can fly straight and level no prob. On the other hand if I tried to fly at 680km/h I'll be doing a big nose up with a lot of drag.

If I want to go higher in the same aircraft I just go faster. When I reach my operational ceiling, if I could magically go faster I could fly higher again.

Greater weight raises your stall speeds, go too far and you will have to raise AoA but only because your stall speed is approaching normal operating speeds, which is essentially described by things like maximum lift loading (or something like that, I get confused about terms occasionally I apolegise but my visualisation is clear).
Another real world example more closely together, 109F versus 109G-6, heavier aircraft, same wings, same AoA, but higher speed cruising conditions (2000rpm and around 430IAS instead of 1900rpm and around 400IAS). Also, faster even where the output increase isn't proportionate to overcome a drag increase associated with more AoA in normal flight as well as increasing speed performance under all conditions. At best the 605A is only 100hp more than the 601E

 

[Knegel]

Hi,

Knegel as I understand it you've been talking about Vmo, not Vmax and we both seem to agree you're not talking about VNE or critical mach.

I wa stalking about Vmax level flight, generally spoken Vmax(i never had any problems with this therm), which always get written in TAS or CAS, not about Vmo, which get written in IAS.

You seem to be missing the most basic description of the four primary aeronautical forces of lift, weight, thrust and drag and the secondary rule to get more lift, just go faster.

Here it is again. So long as you've maintained correct airframe balance installing your extra weight, being heavier doesn't mean you have to raise AoA.

I think its the other way around, as me and also davparlr already did explain, you cant raise the weight of a plane, wihout to raise the power and keep same altitude and speed without to increase the lift.
To increase the lift, you need to increase the angle of attack and this increase the drag and this decrease the speed.

As such "more weight = less speed", while the engine power and altitude stay the same, is absolut correct.

You don't have to start pointing the nose up just because you raised wing loading. The 109G actually has less wing area than the Emil and more weight, but flies at the same AoA at normal speeds.

You be wrong here and what please is "normal speed"??

Drag is not increased when increasing loaded weight, so long as the airframe remains properly balanced and this weight isn't in external protrusions. Stall speeds increase though, so at very low speed you have to raise AoA or put your flaps down sooner, or land faster. It's only at low speeds.

The only time this isn't true is if you've exceeded the maximum wing loading on that airframe design by increasing weight too much for the wing area that you have.

The Messerschmitt has a higher wing loading than the Spit, and it doesn't run around at a higher AoA than the Spit. They both sit at something like 3-deg at cruise and neutral in the high speed condition (handled with elevator trim).

Everything I wrote about thrust, drag, torque and weight is physically sound.

I won't go venture into speed testing conventions and benchmarks as it would be a long conversation which would hijack the thread too much and isn't directly relevant to the point anymore than you said Vmax wasn't. I'm sure we both understand conventions vary between RAF, NACA and USN testing procedures, and then again by the time period (it's a hilarious story how they tested design limitations in the thirties, I'm surprised any test pilots survived, I mean seriously 12g pullouts at 5000 feet in an F3F those Navy guys were insane).

The SpitfireIXc and 109G-2 have almost the same liftload, as such the AoA might be almost the same at same speed. Otherwise "cruise speed" is a variable and if the 109F-2 did fly at same AoA at cruise speed like the 109G6. then this is related to the fact that the 109G6 had a higher cruise speed, cause it had more power.

Cruise speed is the speed of minum drag, its not always at the same AoA and also not at the same speed. With the same airframe, as heavyer the plane, a higher the AoA and also crauise speed increase. If a plane cant reach "cruise speed", cause the plane miss engine power, the plane fly to high(at one stage there just isnt enough power) or is a bad contruction.

Every little different in the weight change the AoA, as long as the plane keeps level flight and same power. Its a pysical law: no action without reaction.

btw, there is one possibility when a plane gets faster with more weight:
This is so when the plane is constructed for a Vmax(level flight) of lets say 500km/h, but with the time the engine got so much more strong and so the speed did increase so much, that the airfoil produce so much lift that the plane need to get trimmed into a negative attack agle to keep a level flight. Due to this the drag would be bigger than the smalest possible drag and so more weight would even this out and leadt to a higher speed.

Greetings,

Knegel

 

[vanir]

To increase the lift, you need to increase the angle of attack and this increase the drag and this decrease the speed.

As such "more weight = less speed", while the engine power and altitude stay the same, is absolut correct.

And yet this is simply not true. If your weight increases enough to have to raise the AoA (a factor of wing loading at a given airspeed), then all you have to do is fly faster to bring the AoA back down again.

Here is what you guys are talking about, economy cruise is roughly speaking the minimum speed the aircraft can do without having to have too high AoA to cause fuel burning drag. If you go slower than your economy cruise, then you get close enough to the stall speed to have to raise AoA and you would actually have to use more power to keep the lower speed. You would use more fuel going slower than you would going slightly faster, because of AoA-induced drag at the slower speed. So the economy cruise setting is a compromise between not too much AoA and as little excess thrust as possible.

Hope you can follow me here.

Let's say our economy cruise is 300km/h at 7-deg Alpha. My stall speed is 270km/h at 30-deg Alpha. To go at 280km/h and 25-Alpha just above the stall speed I would actually use more fuel than I would at 300km/h because of the increase in drag.

Bear with me.

Now I make my plane heavier. My stall speed is now 280km/h at 30-Alpha. If I wanted to do my normal economy cruise at 300km/h I would be at 10-Alpha. OMG you're right I have to raise my AoA because I made the aircraft heavier.
NO WAIT, hang on a minute! I can just increase my economy cruise to 310km/h and I will be back at 7-Alpha.

But because my engine is working a little bit harder I will use a little more fuel in economy cruise when I'm heavier. And I will have to go a little bit faster to maintain the original AoA.

Here's the key point: you guys are talking about maximum level speeds which are well and truly above the stall speeds until you get near the service ceiling. By a lot. Tons of room to play with to keep AoA commonality unless you go absolutely stupid with overloading the plane with extra weight.

I rest my case.

(concluding with my very first point, two examples of the same aircraft, one heavier will have the same Vmax but different maximum level speeds under service conditions. heavier aircraft may run out of fuel before they can reach their previouis maximum level speed when lightened, because you accelerate harder for longer lighter, an inertia thing or that force which resists acceleration, a function of mass).

 

[Knegel]

And yet this is simply not true. If your weight increases enough to have to raise the AoA (a factor of wing loading at a given airspeed), then all you have to do is fly faster to bring the AoA back down again.

Great, and how do you want to do that at Vmax level speed, where you already use max engine power??

Here is what you guys are talking about, economy cruise is roughly speaking the minimum speed the aircraft can do without having to have too high AoA to cause fuel burning drag. If you go slower than your economy cruise, then you get close enough to the stall speed to have to raise AoA and you would actually have to use more power to keep the lower speed. You would use more fuel going slower than you would going slightly faster, because of AoA-induced drag at the slower speed. So the economy cruise setting is a compromise between not too much AoA and as little excess thrust as possible.

Hope you can follow me here.

Let's say our economy cruise is 300km/h at 7-deg Alpha. My stall speed is 270km/h at 30-deg Alpha. To go at 280km/h and 25-Alpha just above the stall speed I would actually use more fuel than I would at 300km/h because of the increase in drag.

Bear with me.

Now I make my plane heavier. My stall speed is now 280km/h at 30-Alpha. If I wanted to do my normal economy cruise at 300km/h I would be at 10-Alpha. OMG you're right I have to raise my AoA because I made the aircraft heavier.
NO WAIT, hang on a minute! I can just increase my economy cruise to 310km/h and I will be back at 7-Alpha.

But because my engine is working a little bit harder I will use a little more fuel in economy cruise when I'm heavier. And I will have to go a little bit faster to maintain the original AoA.

Here's the key point: you guys are talking about maximum level speeds which are well and truly above the stall speeds until you get near the service ceiling. By a lot. Tons of room to play with to keep AoA commonality unless you go absolutely stupid with overloading the plane with extra weight.

I rest my case.

(concluding with my very first point, two examples of the same aircraft, one heavier will have the same Vmax but different maximum level speeds under service conditions. heavier aircraft may run out of fuel before they can reach their previouis maximum level speed when lightened, because you accelerate harder for longer lighter, an inertia thing or that force which resists acceleration, a function of mass).

More speed = more drag, so even if you start all this from cruise speed, and you increase the speed to increase the lift, you increase the drag at same time. You actually increase it in square with the speed.

There is no switch, where more weight change the AoA and so the drag.
Sometimes you wrote something like this " If your weight increases enough to have to raise the AoA", there is no special weight limit at whcih the plane suddenly get pushed downward , every little gram will push you down and so you need to increase the AoA for every little gram and milligram. And 0,01 degree different AoA at highspeed already make a good different.

Do you have an idea why a FW190A5 with 4000kg have a Vmax sea level of 567km/h, while the clean FW190A8 with 4300kg made 556km/h?? I never did calculate what is the AoA different between a 190A5 and 190A8 at this speeds, but be sure, the 190A8s AoA is higher.

It realy dont matter what speeds we are talking about, in a level flight more weight increase the AoA, if you want to keep the AoA constand, you need to increase the speed, both increase the drag. With the exception i wrote above, still the drag change.

So in a level flight this is a fact: different weight = different drag

 

[FLYBOYJ]

As i wrote many times here, maximum speed is not all, but for a less good turning and climb plane its all and everything(P40 vs Zero).
If the P40 would have been 20moh slower, its dive acceleration wouldnt have been as good as well.

I don't quite understand what you're trying to say but I think you're saying that in a close-in encounter, maximum speed is not that important. If so that's been my point from the beginning and I believe that's wahy davparlr eluded to.

Remember what was said here - SEPERATION. That 20 mph advantage will work for a fleeing aircraft if there is enough separation to keep his opponent at bay, keeping clear of any firing solution his pursuer may try to establish. But as stated, if you're trying to run in an aircraft with a 20 mph speed advantage over your opponent and don't have the separation, no WW2 aircraft is going to outrun a bullet.

 

[vanir]

Great, and how do you want to do that at Vmax level speed, where you already use max engine power??

You're just not getting it. You don't need to go faster at the maximum speed because you're far enough above the stall speeds of the aircraft that you will not have to raise AoA when making it a little bit heavier.

You raise the AoA when your airspeed is getting close to the stall speed.

Let me say that again. You raise AoA when your airspeed is getting close to the stall speed.

Your stall speed goes up a when making the aircraft heavier. This is because wing loading.

Maximum level speed is far enough above the original stall speed to not be affected by this except in terms of ceiling.

Say you put bombs on an aircraft. The increased drag slows you down so your cruise setting to get to the combat area maybe close enough to the higher stall speed (caused by lift loading), that you may indeed have to trim more elevator in the cruise (especially if you want to maintain original cruise altitude...which is why fighter-bombers often cruise at lower alt and also to save fuel from more difficult sustained climbs). Your maximum speed with the bombs might be reduced enough by drag that you may indeed have to trim elevator almost to cruise condition when flat out, say 2-alpha instead of neutral (again particularly if you want to retain the clean performance altitude).

But if the weight is internal, drag not being an issue from installation of weight itself, your maximum speed and even maximum cruise are going to be high enough above your stall speeds that you just won't have to raise your AoA for level flight. The reduction in top speed is because acceleration and service use, it is not a reflection of Vmax for the airframe (again why I stipulated you were using the Vmax terminology incorrectly).

The 109G-2 is a lot heavier than the 109F-2 but the airframes are identical. With the 1.35atu restriction on the 605A they both put out 1350PS.
Same output. Same airframe externally. More weight latter. Yet they both fly at neutral trim in the high speed condition (ie. straight and level).

Kills your argument dead.

 

[Shortround6]

You're just not getting it. You don't need to go faster at the maximum speed because you're far enough above the stall speeds of the aircraft that you will not have to raise AoA when making it a little bit heavier.

You raise the AoA when your airspeed is getting close to the stall speed.

Let me say that again. You raise AoA when your airspeed is getting close to the stall speed.

For a given plane at a certain weight the following apply.

For any given speed there is only one angle of attack that will give level flight.

Or

For any given angle of attack there is only one airspeed that will give level flight.

As in cruising at 200mph at angle of attack "A" you have level flight, neither descending or ascending.

If you maintain the same angle of attack but slow to 190 mph your lift will go down and you will start a gentile decent while maintaining the same angle of attack. If you speed up to 210mph and keep the same angle of attack the plane will start to climb gradually.

Or if you add or decrease throttle to maintain 200mph while changing the angle of attack you will climb if you increase the angle of attack (more lift) or descend if you lower the angle of attack (less lift at the same speed).

As the wing changes angle of attack the co-efficient of lift changes.

As the speed increases for a fixed angle of attack the lift increases.
The changes in angle of attack can be a fraction of one degree but hey are happening.

as the weight of the plane goes up you need to generate more lift at the same speed to maintain level flight.

This might only need a very small change in AoA but it is there.

One estimate for a P-51D Mustang claimed that for an increase of 1000lbs loaded weight the speed would decrease by 3mph at 24,500ft using WER power. that is clean condition, no external drag. The decrease is from the extra drag from the change in AoA or induced drag.

 

[davparlr]

But if the weight is internal, drag not being an issue from installation of weight itself, your maximum speed and even maximum cruise are going to be high enough above your stall speeds that you just won't have to raise your AoA for level flight. The reduction in top speed is because acceleration and service use, it is not a reflection of Vmax for the airframe (again why I stipulated you were using the Vmax terminology incorrectly).

Explanations have been clear. You cannot carry weight for free. You prove that every time they weigh your baggage when you get on an airliner. More weight, more lift required, high AoA for given airspeed, more induced drag, higher throttle setting to increase thrust to offset higher drag, more fuel used. If you add weight to a fighter at top speed no more thrust is available to offset the increased induced drag, fighter MUST slow down or pick up a descent rate.

Where did you come up with your position on weight and airspeed?

 

[Knegel]

I don't quite understand what you're trying to say but I think you're saying that in a close-in encounter, maximum speed is not that important. If so that's been my point from the beginning and I believe that's wahy davparlr eluded to.

Remember what was said here - SEPERATION. That 20 mph advantage will work for a fleeing aircraft if there is enough separation to keep his opponent at bay, keeping clear of any firing solution his pursuer may try to establish. But as stated, if you're trying to run in an aircraft with a 20 mph speed advantage over your opponent and don't have the separation, no WW2 aircraft is going to outrun a bullet.

Hi,

all iam saying is that 20mph more maximum level speed is not "pissing against the wind", like someone told.

A 109E with a real maximum speed of 550km/h at height and 450km/h sea level is a different plane than a 109E with 570km/h at hight and 470km/h sea level and thats just 20km/h not mph!!

Around 20km/h, thats the different between combat/climb(30min) and 5min combat power for the 109E!

To achieve 20mph more speed a plane need a way better aerodynamic or much more power.

For the generally same airframe, even if i dont know what is the cause for 20mph more or less, i can safely assume that the faster plane also will accelerate better, zoom up better and also dive faster. Depending to why the plane is faster(less drag or more power) i also can estimate that the plane climb better(more power) or accelerate better in a high speed dive(less drag).

20mph more or less maximum level speed have a impact to the whole flight performence.
You can have a 109E with 450km/h sea level but the same accleration like a 109E with 470km/h sea level.
If the speed difference is related to more power, also the climb and turn performence will change extrem!
And that only with 20km/h, not mph.

20km/h in case of the 109E is equal to around 50PS more or less, in this case thats 5% engine power, 20mph would be more. Thats not pissing against the wind.

Greetings,

Knegel

 

[FLYBOYJ]

Hi,

all iam saying is that 20mph more maximum level speed is not "pissing against the wind", like someone told.

A 109E with a real maximum speed of 550km/h at height and 450km/h sea level is a different plane than a 109E with 570km/h at hight and 470km/h sea level and thats just 20km/h not mph!!

That's the same for ANY aircraft - S/L speed will be lower but the airframe and engine will perform better mainly in climb performance (Vx and Vy)

For the generally same airframe, even if i dont know what is the cause for 20mph more or less, i can safely assume that the faster plane also will accelerate better, zoom up better and also dive faster. Depending to why the plane is faster(less drag or more power) i also can estimate that the plane climb better(more power) or accelerate better in a high speed dive(less drag).

Not always true - you have yet to bring up power to weight ratio for a given aircraft.

"zoom up better?" You man climb?

Go back to the P-40

Was it able to out turn a Zero or Oscar? NO
Was it able to outclimb either aircraft? NO
Was it able to out accelerate either aircraft? Depending on altitude airspeed
Was it able to outdive a Zero or Oscar - YES

This comparison can be made with other aircraft Like the P-47, P-38, etc.

20mph more or less maximum level speed have a impact to the whole flight performence.
You can have a 109E with 450km/h sea level but the same accleration like a 109E with 470km/h sea level.
If the speed difference is related to more power, also the climb and turn performence will change extrem!
And that only with 20km/h, not mph.

And do you have performance charts to back up that claim?

20km/h in case of the 109E is equal to around 50PS more or less, in this case thats 5% engine power, 20mph would be more. Thats not pissing against the wind.

Greetings,

Knegel

If the aircraft is trying to run with no SEPERATION to exploit that 20 MPH advantage, it is pissing in the wind, and that's been the point from the beginning.

 

[Knegel]

That's the same for ANY aircraft - S/L speed will be lower but the airframe and engine will perform better mainly in climb performance (Vx and Vy)

Sure thats the same for any aircraft

Not always true - you have yet to bring up power to weight ratio for a given aircraft.

Sure thats always true. An example is the 109E-4 vs the 109E-4/N or 109E-4/N vs the 109F.
The 1st is the same airfame with more power and around 20km/h(not mph) more speed.
The whole performence is better due to the higher power.
The latter is the same engine with a similar airframe, where mainly the drag is different.
Also here close to 20km/h(not mph) speed difference and the whole plane did count as way better(appart from the guns).

If generally the same airframe show a 20mph different level speed performence, thats the different between speed with WEp or speed with combat power, with all other advantages or disadvantages.

"zoom up better?" You man climb?

Climb out of high speed.

Go back to the P-40

Was it able to out turn a Zero or Oscar? NO
Was it able to outclimb either aircraft? NO
Was it able to out accelerate either aircraft? Depending on altitude airspeed
Was it able to outdive a Zero or Oscar - YES

And if the P40B would have been 20mph slower, it would look like this:
Was it able to out turn a Zero or Oscar? NO
Was it able to outclimb either aircraft? NO
Was it able to out accelerate either aircraft? NO
Was it able to outdive a Zero or Oscar - Depends to the Altitude

Cause when the P40 would have been 20mph slower, there was either less power or way more drag.
Both would influence the dive performence much.

And do you have performance charts to back up that claim?

There is a typo, i actually meant "You cant have a 109E with 450km/h sea level but the same accleration like a 109E with 470km/h sea level. "
Otherwise, if you never saw Bf109E charts with combat/climb and 5min power, iam sorry. Actually i doubt that someone need to proof that a plane with 60PS more power perform all over better.

If the aircraft is trying to run with no SEPERATION to exploit that 20 MPH advantage, it is pissing in the wind, and that's been the point from the beginning.

You dont seems to get the point: The 20km/h difference(in this case, not mph) is a static value, comming from absolut values to give the reader a idea of the whole plane performence.
20km/h more or less in a special situation might not be that much, but 20km/h more maximum level speed of the same plane type is a extreme evolution. Its the step from 109E4 to 109E4N to 109F-2 to 109F-4. How the speed gain get achieved, by drag reduction or increased power dont matter, in combat area the faster of this planes have a all over better performence(zoom climb, acceleration, dive).
if your plane today have a 20mph higher Vmax than yesterday, the probability to end up with just 20mph more speed in front of the same enemy like yesterday will minimize.
In the same situation you will have 40mph or more speed advantage, with a 20mph higher max speed than yesterday you might have a absolut performence advantage so that you can dictate the rule of the combat (109E4/N vs Spit1a would have ben like that, same like SpitV vs 109E).

And if you go back, this discussian started when you told that it dont matter if the Spitfire have a max velocity of 553 or 567mph.

Till now you dont get the point that a maximum speed value is also a indicator for other performences, specialy if you compare basicly the same airframe(Spitfire1 or 109E with an max vel difference of 14mph).

To estimate performence relations based on only the max velocity on different airframes, of course, is not good possible, but with additional knowledge of the power output and weight even this is good possible and still always count:
A higher the max velocity on the same or similar airframe is, in all normal cases the whole performence will be better.

 

[vanir]

Explanations have been clear. You cannot carry weight for free. You prove that every time they weigh your baggage when you get on an airliner. More weight, more lift required, high AoA for given airspeed, more induced drag, higher throttle setting to increase thrust to offset higher drag, more fuel used. If you add weight to a fighter at top speed no more thrust is available to offset the increased induced drag, fighter MUST slow down or pick up a descent rate.

Where did you come up with your position on weight and airspeed?

you're wrong.

do me a favour, check the altitudes on the Vmo of the lighter/heavier Spits, you'll find a disparity

altitude, not Vmax is affected. if you wanted to keep the same altitude...


edit. and fyi peoples, Vmax is on the airframe, not the condition.