Jet Fighter vs. Propeller Fighter Turning Characteristics

[claidemore]

Me262 test pilot Hans Fay maintained that the Me262 had "poor maneuverability", though he also said it turned better at high speeds than at low. He also said it had good response to ailerons at all speeds. Obviously those comments are pretty open to interpretation!

The only account I have read of an Me262 engaging in a turn fight was against Ivan Khozedub, and that resulted in Khozedub shooting down the 262. There may be others, but I haven't read them.

I calculate a turn radius of 4930 ft and time of 46 seconds at 450 mph pulling about 3 G in a Me262. Sustained turn rate at this speed will be about 6.5 degrees per second according to the charts posted earlier. A Spit or Mustang, 350 mph, @ 3G, radius is 2980 feet and time of 36 seconds and could have a sustained turn rate of about 8 degrees per second at that speed. The prop fighter can definately outturn a jet fighter by not trying to match it's speed, and staying inside the jets turn. Note: it takes the prop fighter 1.5 to 2 seconds to relax it's turn and 'cut across the circle' to close to firing range in that scenario, albeit a fairly short firing time given the speed difference.

There is a proplem with claiming a dogfight advantage in a plane because it retains speed better in a turn. IF both planes try to stay at 400mph, the jet is going to have an advantage, but what prop pilot is going to try to keep his speed up while a jet is closing on his tail? It's just not going to happen in the real world, he's going to increase his turn, and because he can lose speed quicker (more drag), he will turn tighter, denying the jet a firing solution.

The jet has an enormous tactical advantage with its superior speed, and will use that to dictate an energy fight, rather than an 'angles' or turning fight.

As for climb, Soren posted a chart here:
http://www.ww2aircraft.net/forum/aviation/me-262-performance-12011.html

-which shows projected climb times for a 004C Jumo engine (more powerful than the 004B engines used in production 262s). It shows a climb time to 10 k at full weight of 19minutes, and 10 minutes at reduced weight. Real operational weight would be somewhere between those two figures, and climb rate of an operational 004B engined 262 would be a bit lower. For arguments sake, even if we use the data for the 004C, the climb rate is at best only at par with contemporary prop fighters and fully loaded, it's not as good.

However, the 262 would zoom climb better due to it's high speed, and to be fair, 'best climbing speed' was faster. In essence, it might not gain altitude on a pursuing Mustang or Spitfire, but would gain distance during the climb. (this is backed up by combat reports against 262's, they usually escaped in level flight or shallow dive) Either way, the prop fighter isn't going to catch it.

The Me262 was a very good fighter, with a kill ratio of 5-1 (maybe 3-1 if you correct for overclaiming). But lets put the credit for that success where it belongs, vastly superior speed and firepower, not dogfighting ability.

 

[FLYBOYJ]

Me262 test pilot Hans Fay maintained that the Me262 had "poor maneuverability", though he also said it turned better at high speeds than at low. He also said it had good response to ailerons at all speeds. Obviously those comments are pretty open to interpretation!

The only account I have read of an Me262 engaging in a turn fight was against Ivan Khozedub, and that resulted in Khozedub shooting down the 262. There may be others, but I haven't read them.

I calculate a turn radius of 4930 ft and time of 46 seconds at 450 mph pulling about 3 G in a Me262. Sustained turn rate at this speed will be about 6.5 degrees per second according to the charts posted earlier. A Spit or Mustang, 350 mph, @ 3G, radius is 2980 feet and time of 36 seconds and could have a sustained turn rate of about 8 degrees per second at that speed. The prop fighter can definately outturn a jet fighter by not trying to match it's speed, and staying inside the jets turn. Note: it takes the prop fighter 1.5 to 2 seconds to relax it's turn and 'cut across the circle' to close to firing range in that scenario, albeit a fairly short firing time given the speed difference.

There is a proplem with claiming a dogfight advantage in a plane because it retains speed better in a turn. IF both planes try to stay at 400mph, the jet is going to have an advantage, but what prop pilot is going to try to keep his speed up while a jet is closing on his tail? It's just not going to happen in the real world, he's going to increase his turn, and because he can lose speed quicker (more drag), he will turn tighter, denying the jet a firing solution.

The jet has an enormous tactical advantage with its superior speed, and will use that to dictate an energy fight, rather than an 'angles' or turning fight.

As for climb, Soren posted a chart here:
http://www.ww2aircraft.net/forum/aviation/me-262-performance-12011.html

-which shows projected climb times for a 004C Jumo engine (more powerful than the 004B engines used in production 262s). It shows a climb time to 10 k at full weight of 19minutes, and 10 minutes at reduced weight. Real operational weight would be somewhere between those two figures, and climb rate of an operational 004B engined 262 would be a bit lower. For arguments sake, even if we use the data for the 004C, the climb rate is at best only at par with contemporary prop fighters and fully loaded, it's not as good.

However, the 262 would zoom climb better due to it's high speed, and to be fair, 'best climbing speed' was faster. In essence, it might not gain altitude on a pursuing Mustang or Spitfire, but would gain distance during the climb. (this is backed up by combat reports against 262's, they usually escaped in level flight or shallow dive) Either way, the prop fighter isn't going to catch it.

The Me262 was a very good fighter, with a kill ratio of 5-1 (maybe 3-1 if you correct for overclaiming). But lets put the credit for that success where it belongs, vastly superior speed and firepower, not dogfighting ability.

Great post Claidemore, another comment on the "maneuverability" comment of Hans Fay – these pilots were jumping into this new technology coming off the ear of the bi-plane. Many of these test pilots were "good-ole stick and rudder guys" that got their training in biplanes and other highly maneuverable aircraft and jumping into something that was sluggish at low speed with little throttle response was something of a new thing.

 

[Soren]

Claidemore,

The big no no in a Me-262 and any other early Jet was to engage in a low speed turn fight with a piston engined fighter, which is what happened in the incident with Ivan Khozedub. The reason for this was the low acceleration of the Jet engines at low speeds, and the ability of piston engined fighter to hang on the prop.

The situation is completely reversed at high speed though, where the Me-262 will out-turn ANY piston engined fighter, the energy retention and acceleration being much greater.

Hans Fey was of the opinion than the Me-262 lacked maneuverability as the roll rate was low, something which every 262 pilot agrees upon. However the turn performance was very good, esp. at high speeds, something which Hans Fey mentions in his report and is confirmed by German, British UK test pilots. There's no mistaking this.

As long as the speed was kept above 450 km/h the Me-262 has the advantage in acceleration, and therefore angles fighting.

As for pulling G's, well assuming the CLmax is 1.52 (Which is being very conservative) the Me-262 will be capable of pulling the following:

At 6,400 kg - 5,700 kg

450 km/h = 5.04 G - 5.66 G
500 km/h = 6.23 G - 7.00 G
550 km/h = 7.53 G - 8.46 G
600 km/h = 8.97 G - 10.07 G
650 km/h = 10.52 G - 11.82 G
700 km/h = 12.20 G -13.70 G

Now since the average pilot couldn't withstand much more than 5 G's the Me-262 will have the advantage in an angles fight at speeds above 450 km/h. So unless the pilot in the piston engined fighter pulls over 5 to 5.5 G's at 450 km/h (or way above that as speed increases) he isn't going to get out of the Me-262's sights.

Now ofcourse if the turn fight is prolonged and the piston engind fighter keep decreasing its speed to below 450 km/h then the Me-262 will have to break off and regain energy.

As for the Climb chart I presented, remember that the 19min time to climb 10km was at 6,900 kg, 500 kg heavier than normal (6,400 kg). Half a ton lighter the Me-262A-1a would reach that altitude allot faster, probably in 13 to 13.5 min, and at 5,700 kg in 10.5 min.

 

[HoHun]

Hi Claidemore,

>IF both planes try to stay at 400mph, the jet is going to have an advantage, but what prop pilot is going to try to keep his speed up while a jet is closing on his tail?

Good analysis! The propeller fighter could always afford a sharp, energy-costly turn while the jet could not afford one as readily - the jet would gain energy back only at a much slower rate initially.

In a one-versus-one, a forewarned propeller fighter would be very difficult to outmanoeuvre with a jet.

The advantages of the jet really are its capability to engage or disengage easily, the high speed that means it can get into position for a surprise attack very quickly (lessening the chances of being detected in time by the defender), and the capabilty for high-speed zoom climbs so that it can approach targets from below (where it's hard to spot) without giving away the energy advantage.

And in a many-versus-many, turn manoevrability loses much of its importance anyway - it's mainly a defensive strength in such a fight.

Regards,

Henning (HoHun)

 

[Soren]

I somewhat agree, as a very sharp and prolonged tight turn quickly can cut speed to down below 450 km/h. However if the engagement speed is 600 km/h the Jet can easily afford to pull lead for a while before having to break off and regain speed.

 

[davparlr]

Davparlr,

A jet looses speed in maneuvers much much more slowly than a piston engined fighter, the reason being a Jet is a MUCH cleaner a/c, and at high speeds its also got more power available. This is simple fact, there's no point in trying to deny it Davparlr.

It could be spic and span but under 4 g's of maneuvering the induced drag will overwhelm the pitiful thrust available from the early jet engines and the prop plane and both planes WILL decelerate, however, slow speed is the friend of the prop and the enemy of the jet.

And this is pretty much universal when comparing Jets to propeller a/c, as the prop whilst generating allot of thrust also generates allot of drag

I don't think a propeller produces drag when it is producing thrust equal to or greater than the aircraft drag.

At the same time the efficiency of the prop falls off quickly as speed increases, whilst the Jet keeps a constant amount of thrust during the entire speed regime.

And the inverse of this is precisely why prop fighters quickly gain an advantage as airspeed decreases.

So FLYBOYJ is completely right when he says that Jets are allot slicker than piston engined a/c.

The P-80 has a zero lift drag coefficient of .0134 and the P-51 has a zero lift drag coefficient of .0161, the P-80 has 83% of the drag of the Mustang, not a lot. An F-4 Phantom has a zero lift drag coefficient of .0224, or, not as slick as the P-51.

And like he says Jets are very reluctant to loose speed, which is one of the prime reasons you need reschooling before going from piston engined a/c to Jets. This very high energy retention is one of the major suprises to the German test pilots when they first flew the Me-262, the reluctance to loose speed during the turn in approach often forcing them to go around for a second try. (I'm sure FLYBOYJ has had a couple of these as-well when he first started flying jets)

Again, when you pull the throttle back on a prop job, the propeller starts generating drag as the air flow tries to turn the propeller (in a piston engine, this is against engine compression). In a jet, when you throttle back, no drag is created. If you could feather the propeller, or if the propeller fell off, I think you would find it much harder to reduce speed as compared to an unfeathered prop and be more similar to a jet. This is the main force differentiating flying final in a prop or a jet, not the "slickness" of the airframe.

There is a proplem with claiming a dogfight advantage in a plane because it retains speed better in a turn. IF both planes try to stay at 400mph, the jet is going to have an advantage, but what prop pilot is going to try to keep his speed up while a jet is closing on his tail? It's just not going to happen in the real world, he's going to increase his turn, and because he can lose speed quicker (more drag), he will turn tighter, denying the jet a firing solution.

This is correct. But also, it must be pointed out that both aircraft will decelerate when pulling "gs". This gives the prop fighter an advantage as dogfight airspeed will continue to deteriorate as gs are maintained.

As long as the speed was kept above 450 km/h the Me-262 has the advantage in acceleration, and therefore angles fighting.

How do you maintain this while pulling gs?

Now since the average pilot couldn't withstand much more than 5 G's the Me-262 will have the advantage in an angles fight at speeds above 450 km/h. So unless the pilot in the piston engined fighter pulls over 5 to 5.5 G's at 450 km/h (or way above that as speed increases) he isn't going to get out of the Me-262's sights.

Now ofcourse if the turn fight is prolonged and the piston engind fighter keep decreasing its speed to below 450 km/h then the Me-262 will have to break off and regain energy.

I somewhat agree, as a very sharp and prolonged tight turn quickly can cut speed to down below 450 km/h. However if the engagement speed is 600 km/h the Jet can easily afford to pull lead for a while before having to break off and regain speed.

If you calculate the induced drag at 25k ft and 600 km/hr, I think you will find that it is many times higher than the jet thrust available and that deceleration will be very high and the jet will get quickly into trouble. I would suspect he could only do about a half turn and if he hasn't got the prop plane by then he better unload and build up energy. I don't think this is good dogfighting ability.

 

[Soren]

Davparlr,

With lift comes drag, it's inevitable. Thus while a prop certainly provides thrust, it also generates drag.

As to the Cd0 figures where did you get these from ? (I suspect the P-51's is for a mock up a/c without a prop)

The Cd0 of the Me-262 is 0.0115 IIRC.

As for the Phantom, well that's not surprising at all, Cd0 of many modern fighter s quite high, but their thrust figures are at the same token also extremely high.

 

[FLYBOYJ]

Again, when you pull the throttle back on a prop job, the propeller starts generating drag as the air flow tries to turn the propeller (in a piston engine, this is against engine compression). In a jet, when you throttle back, no drag is created. If you could feather the propeller, or if the propeller fell off, I think you would find it much harder to reduce speed as compared to an unfeathered prop and be more similar to a jet. This is the main force differentiating flying final in a prop or a jet, not the "slickness" of the airframe.

While you are correct you describe the "slickness" I spoke about. The jets I've flown seem like they don't want to slow down, but their engines are slow in spooling up, a somewhat tricky situation. In a propeller driven aircraft it accelerates quickly and slows down quickly.

Of course that comparison would be void if we're talking about a modern fighter, especially with AB.

 

[davparlr]

Davparlr,

With lift comes drag, it's inevitable. Thus while a prop certainly provides thrust, it also generates drag.

That's true, but induced drag is perpendicular to lift so the drag of the propeller is operating against the torque of the engine, not the forward direction of the airframe. I've got to tell you that this is way out of any expertise I have, but just seems to make sense. When I looked up propeller drag, all I found was windmilling drag. None identified drag on the aircraft of a propeller generating thrust.

As to the Cd0 figures where did you get these from ? (I suspect the P-51's is for a mock up a/c without a prop)

I just googled zero drag coefficients of the P-80, 51, and F-4. This is a pretty good site for this kind of data (unfortunately the Me-262 Cd0 is missing)
contents

The Cd0 of the P-51 is undoubtedly without propeller. I have never seen Cds calculated with the propeller included. Another hint that it is not a function of overall aircraft parasitic drag.

The Cd0 of the Me-262 is 0.0115 IIRC.

I've only seen it in one place and it showed .02, but I have no confidence in the site, could be a gamer site.

As for the Phantom, well that's not surprising at all, Cd0 of many modern fighter s quite high, but their thrust figures are at the same token also extremely high.

Actually, most modern, well, 60's anyway, fighters are quite low. Here's a few, F-105, .0173, F-8, .0133, and the best I have found, F-106, .0083. The F-4 is kind of a dog with huge engines, which cures a lot of sins.

 

[claidemore]

Now since the average pilot couldn't withstand much more than 5 G's the Me-262 will have the advantage in an angles fight at speeds above 450 km/h. So unless the pilot in the piston engined fighter pulls over 5 to 5.5 G's at 450 km/h (or way above that as speed increases) he isn't going to get out of the Me-262's sights.

Now ofcourse if the turn fight is prolonged and the piston engind fighter keep decreasing its speed to below 450 km/h then the Me-262 will have to break off and regain energy.

This scenario where the jet is already in the rear hemisphere of the prop plane is an ideal situation, and is not really an example of an angles fight. The jet in that scenario only has to adjust his turn a few degrees to keep the guns on the prop fighter, while the prop fighter has to move his plane through several degrees to escape. That is basically a 'bounce' situation, where arguably the jet is employing a better high speed turn rate to stay behind the other fighter for a short time.

The question is, can the jet use the high speed turn rate to get into the rear hemisphere in the first place; and to make a fair comparison of turning ability you have to start both planes on an equal footing.

ACM 101. The 'slick' jet cannot trade energy for angles as efficiently as a 'draggy' propeller driven plane.

The argument about which has the better sustained turn rate at what speed is moot. The prop fighter simply does not have to match the speed of the jet, in fact he cannot match it.

If you look at the graphs provided by HoHun, you see that the best turn rate for the jet is 8 degrees per second, while the prop plane enjoys a best turn rate of 12 degrees per second. That's a 33% turn advantage.

Those graphs are generic, but they illustrate the rule very well.

That 33% advantage means that if the positions of the planes are even at the start of the engagement, ie they are at opposite sides of the circle, it can take as little as 1 1/2 turns for the piston plane to be in the rear hemishpere of the jet. (120 degrees in 30 seconds, and you only need 180 degrees to be right on his tail)

Your second statement above Soren, is absolutely correct and illustrates good energy tactics. The jet can pull lead on the prop plane for a few/several seconds, but if he doesn't get a shot pretty quick, he should reverse his turn and seperate.

 

[davparlr]

Actually, the entire argument is moot. The Me-262 was a plane of the future and the propeller planes were of the past. There ain't too many prop driven fighters in the air today.

 

[HoHun]

Hi Davparlr,

>When I looked up propeller drag, all I found was windmilling drag. None identified drag on the aircraft of a propeller generating thrust.

The drag of a propeller generating thrust is accounted for by the propeller efficiency factor.

Propeller drag (expressed as a power) is propeller shaft power minus effective propulsive power.

That's taken into account in my calculations for the generic propeller fighter, of course.

Regards,

Henning (HoHun)

 

[Soren]

I've only seen it in one place and it showed .02, but I have no confidence in the site, could be a gamer site.

Hehe, the Me-262's Cd0 is far lower than the P-51's that's for sure, and lower than the P-80's as-well.

.02 is waay too high and in the same league as the 109 Spit.

Where did you see the figure ?


As for propeller drag, well a prop works by generating lift, creating a low pressure infront of itself and a high pressure behind itself. With this lift however comes drag, but despite this there's also the frontal disc area of the propeller, the props themselves being hit directly by the airstream. Hence why no prop fighter is able to brake the sound barrier, the prop simply generates way too much drag at high speeds.

The Jet fighter on the other hand is very "slick", being much cleaner than the piston engined fighters, lacking all the cooling ducts etc etc. Hence why everyone who flew the Me-262 noted how it kept its speed in tight turns much better than any prop fighter, German, UK US pilots all noting the same.

 

[Holtzauge]

Hehe, the Me-262's Cd0 is far lower than the P-51's that's for sure, and lower than the P-80's as-well.

.02 is waay too high and in the same league as the 109 Spit.

Where did you see the figure ?


As for propeller drag, well a prop works by generating lift, creating a low pressure infront of itself and a high pressure behind itself. With this lift however comes drag, but despite this there's also the frontal disc area of the propeller, the props themselves being hit directly by the airstream. Hence why no prop fighter is able to brake the sound barrier, the prop simply generates way too much drag at high speeds.

The Jet fighter on the other hand is very "slick", being much cleaner than the piston engined fighters, lacking all the cooling ducts etc etc. Hence why everyone who flew the Me-262 noted how it kept its speed in tight turns much better than any prop fighter, German, UK US pilots all noting the same.

Well one well known aerodynamic resource book, Hoerner Fluid Dynamic drag by S. F. Hoerner, gives the following values:

Table on page 14-9:

P51 Mustang: Cds=0.017
Me262: Cds=0.021
P-80: Cds=0.02

Cds is drag coefficient based on wing area which I assume you refer to as Cd0 above.

I gather you are convinced that the opposite is true (that Me262 has a lower Cd0 than the P51). What do you base this on? Source?

 

[drgondog]

Well one well known aerodynamic resource book, Hoerner Fluid Dynamic drag by S. F. Hoerner, gives the following values:

Table on page 14-9:

P51 Mustang: Cds=0.017
Me262: Cds=0.021
P-80: Cds=0.02

Cds is drag coefficient based on wing area which I assume you refer to as Cd0 above.

I gather you are convinced that the opposite is true (that Me262 has a lower Cd0 than the P51). What do you base this on? Source?

Just an aside but Cd0 is CD at zero lift to take induced drag out of the equation. I suspect the induced drag is also higher for both the P-80 and Me 262 but I haven't looked - so the statement is from a place where the sun does not shine.

 

[drgondog]

Hehe, the Me-262's Cd0 is far lower than the P-51's that's for sure, and lower than the P-80's as-well.

.02 is waay too high and in the same league as the 109 Spit.

Where did you see the figure ?


As for propeller drag, well a prop works by generating lift, creating a low pressure infront of itself and a high pressure behind itself. With this lift however comes drag, but despite this there's also the frontal disc area of the propeller, the props themselves being hit directly by the airstream. Hence why no prop fighter is able to brake the sound barrier, the prop simply generates way too much drag at high speeds.

The Jet fighter on the other hand is very "slick", being much cleaner than the piston engined fighters, lacking all the cooling ducts etc etc. Hence why everyone who flew the Me-262 noted how it kept its speed in tight turns much better than any prop fighter, German, UK US pilots all noting the same.

Soren, with all due respect every encounter report I have seen (survivors obviously) which is 30+ indicated the 'evade' manuever for a trailing Me 262 was a tight climbing turn.

The surviving 262 continued on, rather than try to turn. The non-suviving 262 turned with the 51 w/o attempting to use superior speed to climb back up and turn back to re-engage once again.

The 355th/2SF got 7-1-6 Me 262 air awards (6 pilot bail outs, 1 blew up) between March 1 and April 7 plus one Ar 234(blew up). The one that was blown up was probably severely damaged in the chase but tried to out run the 51s and land quickly to save his aircraft, rather than bail out.

At the same time they lost none to the Me 262... which says obviously that they were not suprised from behind!

All the encounters were at high speed and at 18-30K feet altitude.

The one that blew up was hit from a chase which lasted 20+ miles from 25,000 feet to final approach at Ingolstadt where he blew up, out in front of the Mustangs by about 2 miles.

That is only ~ 5-7% of all the Me 262s awarded to 8th FC in the air so not a comprehensive statistical sample. Nevertheless, there were no examples of an Me 262 out turning these Mustangs and none of the awards were for a 262caught taking off or landing.

I Know quite a few were shot down on the deck for those reasons, but it would take a research project to collect and review all the Encounter Reports to get a sample distribution. I intend to do that when I am fully retired.

 

[Holtzauge]

Just an aside but Cd0 is CD at zero lift to take induced drag out of the equation. I suspect the induced drag is also higher for both the P-80 and Me 262 but I haven't looked - so the statement is from a place where the sun does not shine.

I think the Cds in the numbers I quoted above refers to Cdo but I'm not sure. But even if the Cdi is included or not this does not really change the numbers:

Ballpark: Assuming Cl at around 0.1 (high speed), aspect ratio around 6, oswald factor circa 0.8 this gives:

Cdi= Cl**2/(pi*A*e)=0.0007 which is insignificant in the comparison

 

[davparlr]

Hehe, the Me-262's Cd0 is far lower than the P-51's that's for sure, and lower than the P-80's as-well.

.02 is waay too high and in the same league as the 109 Spit.

Where did you see the figure ?

An Italian site.

http://digilander.libero.it/Dany_Aerospace/Messerschmitt/Me262_Mission.m

 

[drgondog]

Just an aside but Cd0 is CD at zero lift to take induced drag out of the equation. I suspect the induced drag is lower for both the P-80 and Me 262 but I haven't looked - so the statement is from a place where the sun does not shine.

The aspect ratio for the 262 is ~ 6.9 to 5.85 for the 51

 

[davparlr]

Hehe, the Me-262's Cd0 is far lower than the P-51's that's for sure, and lower than the P-80's as-well.

The comparison to the P-80 is a source of confusion. At sea level, the P-80, with equivalent thrust and similar weight, has a top speed 50 mph faster than the Me-262 (558 to 508). Top speed at sea level vs. thrust is a good indication of aircraft "cleanliness".