WW2 fighter turning performance comparisons

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Kukuruznik said:
Its interesting that these two performance indicators are not usually given in aircraft data although apparently considered very important by the pilots.

Cheers
Click to expand...

These are not put in aircraft performance charts because turn rates vary with bank angle and speed, also factor in aircraft loading and weight. Not necessarily finite numbers that would be of interest of pilots during the heat of combat especially when you could manipulate the turn by skidding or slipping.
 

That diagram is very interesting, but it has some contradicitons with other AFDU material, even the one you can find on the same site.
For example the Mustang3 is highly rated on this diagram while FW190 turns out to be very poor.
However this is what MustangMkIII tactical trial has to say about it and I quote:

"Turning circle
42.Again there is not much to choose. The Mustang is slightly better...."
That was against BMW801 engined FW190, who knows which one and in what condition. Would you say that above diagram says "not much to choose" and "slightly better"?
 
I would think a major factor in turning would be the condition of the pilot if he was in superb condition he might be able to turn to the aircrafts potential realizing G suits were not in vogue during this period
 

Which is close to the thesis of Energy Manueverability and subsequent generated airframe design performance criteria that Boyd developed at great personal career sacrifice in USAF in the 50s and 60s - leading to the F-16 and F-15s

He`crafted the concepts at USAF Fighter School at Nellis post Korea and demonstrated to everyone's dismay that ALL the multi role fighters we had in ops and on the boards were inferior in fighter to fighter Energy manueverability to the Mig19 and Mig21 - and sure enough proved it in VietNam
 

Hey Mike - as a cynic I might have suggested a couple of months back that the prime off line instructions to the Navy pilots conducting the tests "Don't come back with a conclusion that the 51 is superior in any way" - which is why the Patuxent River tests are not accompanied by Turn and acceleration comparisons at various speeds and altitudes - lol - but definitely accompanied by statements that the F4U out turned, accelerated and climbed better -
 

Yes, ok, but good pilots knew what their aircraft could take (and they could take in terms of Gs), and in most memoirs the words 'turn' and 'roll' are mentioned very frequently. I'm looking for optimum of course, as any pilot of the period would be also.
The problem with memoirs is that they give descriptions of combats that rarely provide technical data (of course!), and this data is not readily available from other sources I find.
Of course its early days in my research, so I may be able to dig up something eventually. However given all the sites online dedicated to study of WW2 combat aircraft, I am rather surprised of the lack of data on these two aspects of air combat...or even discussion.

Cheers
 
For what you're looking for your going to have to ask the respective engineer. For the most part when you're in an aircraft and turning there is one instrument your going to use, and it comes in two different configurations depending of the size of your aircraft...




 
There are a couple of very practical reasons why sustained level turn ability is much more important to today's computer gamer than it is to a fighter designer or pilot in RL.

Facts are all aircraft at the same velocity and angle of bank will make exactly the same turn.

That is a very powerful fact. Sustained turning ability is a function of the fundamental relationship of aircraft performance, power available to power required. However, the most important factor in turn performance is velocity. The slower aircraft will always outturn the faster aircraft.
In BGS terms:

Radius of turn = Velocity in Knots^2 divided by the product of correction factor of 11.26 because we are using Knots and the tangent of the angle of bank.

r = Vk^2 / (11.26* tan AOB)

The portion of the envelope in which any design contemporary fighter has an advantage over another design is very small.

This small portion occurs at the popular term of flying at the edge of the envelope.

My experience comes as a pilot, aircraft owner, and someone formally trained in aerodynamics. I throw a big BS flag on any claims of consistent flight at the edge of the envelope. Pilots certainly may come close to "the edge". Many have to change their shorts when they do brush up against it. Many pilots are dead after thier first real brush with the "edge". Facts are flying at any portion of "the edge" is very detrimental to controlled flight and in the majority of cases downright deadly.

Some quick examples:

1. Flying at the "edge" of the cruise envelope all it takes is a gust of wind to damage or destroy the airframe.

The red line is preceded by a yellow band which is the caution area, which runs from VNO (maximum structural cruise speed) to VNE
Click to expand...

Airspeed indicator - Wikipedia, the free encyclopedia

2. Flying at the "edge" of our turn performance envelope, that same gust of wind will induce a stall and chances are it will be an aggravated or uncoordinated stall. Now we are in danger of experiencing a spin.


AOPA Online - ASF Article of the Month - Safety Pilot: Spinning In

If it occurs without sufficient altitude to recover we have lost our life.

No matter what "edge" you choose, there is a very real danger of turning our controlled flight into a fight for survival. That is not even factoring in another airplane with a pilot trying to kill us!

It takes a very skilled and experienced pilot to fly the highest performance and most technologically advanced aircraft of the day anywhere close to the edge. The kind of skill and experience only a small percentage of pilots in any given force are capable of exhibiting.

Given the reality of flight and the fact aircraft performance is not an absolute but rather a percentage range over a mean average, only a handful of WWII designs stand out as having a sustained turn performance that would even be noticeable in the air.

If anyone is interested, I have done the calculations for several WWII fighter design sustained turn performance and could post the results as well as the methodology used.

All the best,

Crumpp
 

 

Crumpp - With enormous respect to you, I agree everything you said except the flat statement that

Facts are all aircraft at the same velocity and angle of bank will make exactly the same turn.

If you mean by the above statement that all exact model aircraft at same weight and configuration (external stores) - then I agree

For dissimilar aircraft entering that turn I would disagree as I think you would also. The "G" forces will be exactly the same as long as the velocity and angle of bank are the same - but aerodynamics (energy bleed) and wing loading and airfoil properties will immediately enter into the equation

Not all a/c could 'maintain' the same angle of bank and airspeed given reasonably close thrust to weight equivalency. I have in mind an F-105 in a turn with a Jap Zero to illustrate the problem with the concept.. or even a very light F105 in a turn with a heavily loaded one.

For every other comment I am in violent agreement
 
Hi drgondog,

Thank you for the kind words.

I think you misunderstood what I wrote regarding turn performance. Don't worry it is a difficult concept to grasp but as I said, it is a very powerful fact of aircraft performance. You will begin to see why sustained level turn is just not very important to a fighter designer.


Radius of Turn

Turn performance is based on the relationship of power available to power required. In a very simplistic form, wing loading is a reflection of this relationship. However aircraft are a system and not one characteristic. The designers in WWII were very competent and I would even venture to say much more competent in high power piston aircraft design than we are today. There simply is not much of a market for 2000hp single engine aircraft.

Not all aircraft can sustain the same angle of bank at the same velocity. The L/D characteristics of the design play a very important role. In fact all aircraft performance depends on the L/D curve.

For WWII fighter design contemporaries, the differences are a very small portion of the total maneuvering envelope.

In your example, the F-105 simply cannot travel as slow as the Zeke, velocity being the key component to turn radius.

Now the Zeke cannot travel as fast as the F-105 either. So at the higher velocities the F-105 is comfortable maneuvering, the Zeke cannot sustain the same turn performance.

Just as excess power extends into the low velocity realm, it also extends into the high velocity realm. At Vmax, an airplane only has enough power to sustain wings level flight.

In the graph above the red lines represent the radius of turn for any airplane, at 10,20...80 degrees of bank. Keep in mind that the radius of turn equation is universal, therefore this graph is valid for any airplane, from a C-150 to a Boeing 747.
Click to expand...

The blue line in the graph is for an airplane with a stall speed of 60 knots in straight and level flight. This line will be different for every airplane of course.
Click to expand...

Minimum Radius of Turn

You can confirm this aerodynamic fact easily with the following program:

Gyles AeroDesign - Freeware Turn Radius Calculator

All the best,

Crumpp
 

Crumpp - I wasn't having a problem grasping the concepts - strictly to the statement and question I posed. Like you I have both the education and the experience behind the stick to agree the points you made.

In my example with the Zeke I was perhaps not clear enough.

The F-105 could in fact fly at 300 kts, and enter a turn with a Zero at three hundred kts, and not be able to keep up in the turn radius no matter how much power is subsequently added by the 105 jock to try to maintain bank angle...

If he continued to try to maintain the turn and the rule of this engagement is a.) do not add any more throttle, and b.) put the engagement on the deck, the 105 will be severely out turned by the Zero.

I would pose the same outcome for a MiG21 and F-105 entering a turning fight on the deck, each entering at 550 kts and let the 105 be able to increase his power to all available as he is faster on the deck. The 105 would be able to enter with the same bank angle but would not be able to sustain it (or lose bank angle/energy less slowly than the MiG).

This is the end of my only rebuttal to a statement that I think you did not mean in the context I parsed it..

As to 'not very important', at low altitude and very little excess energy available to break combat with a fighter with significantly better turn performance....it might be critical.

As to the pilot who knows his ship and understands the strengths of his speed and zoom, then he avoids the circumstances above - and makes it 'less important' -

And to your point a superior pilot (say, in a P-47) on the deck might be able to outfly the inferior pilot in a 109 or 190 in a turn, entering at the same speed and bank angle, and defeat them by being able to skirt closer to the stall - in which case as you pointed out, the turn radius (optimal) was not the critical factor, but the skill of the pilot in the a/c with 'inferior' turn potential performance and his ability to ultimately 'out turn' the better a/c in that manuever.

This is a lot of words for what I thought was a minor point of disagreement for a literal statement I wasn't sure you meant - <smile>

If you meant it, I tip my hat and withdraw from the debate.

Regards,

Bill
 
I admit that I am with Drgondog on his comments about radius of turn. Some aircraft have lift devices that enable them to reduce the turn radius for a given speed. This must be reflected in the final result somewhere along the line.
Weight surely must also play a part. The heavier plane is going to have a harder time in the turn due to the additional forces in play trying to 'throw' the plane out of the turn, plus of course wing design. I cannot see an F104 staying, say with an F86 in a turn at the same speed and bank, due to the different amount of lift generated by the wing.

Also isn't there a significant danger in looking at this in isolation. For example the roll rate has a major impact on how long it takes to get into a bank for the turn to take place. I have some experience in gliders and I am confident nothing powered could keep up with me in a turn, but my roll rate is shocking and to get into a turn takes an appreciable amount of time compared even to a simple Cessna.
 
The F-105 could in fact fly at 300 kts, and enter a turn with a Zero at three hundred kts, and not be able to keep up in the turn radius no matter how much power is subsequently added by the 105 jock to try to maintain bank angle...
Click to expand...

If we are not considering the effects of power then yes, our F-105 would turn exactly the same as our Zeke at 300KEAS at the same angle of bank. It could keep up and match turn performance exactly. There would be no difference in the two aircraft's turning ability.

However power available to power required is the fundamental relationship of aircraft performance. We have to consider the effects of power.

Lets just use EAS so we can simply things by eliminating density effects.

Actually the Zeke is incapable of turning at 300KEAS. In fact it is incapable of even reaching that speed in KEAS in level flight. It does not have the power available. If the pilot attempted to turn at 300Kts he would have to trade altitude for airspeed if he wanted to maintain 300KEAS.

The F-105 would end up above him.

The Zeke could give up energy in the form of airspeed to maintain alitude. As he travels at a slower velocity he will now turn a smaller radius but will have lost energy.

Here we can see the Zeke 52 maximum sustain load factor using TAIC data:



Here is the excel spreadsheet data from the sheet I designed:



Here we can see the P47D-22 using AHT data at combat weight. Notice the curve is very similar to the Zeke's. However the Zeke can sustain this at a much lower velocity. The P47D-22 however can sustain a turn at 250KEAS of 2.76G's while the Zeke can only sustain 1.5G's at 250KEAS.



Now which would you rather dogfight in? The aircraft that has to give up a large portion of its energy to maneuver or the aircraft that can remain fast and still maneuver?

Speed is life.

All the best,

Crumpp
 
I have some experience in gliders and I am confident nothing powered could keep up with me in a turn,
Click to expand...

Certainly it can outturn most "powered" aircraft for a while at least. Your glider has much more power available than a Cessna as long as it exchanging PE for KE to maintain that altitude. It uses it's lightweight and low drag to gain the advantage in Pa. Great example of how L/D characteristics determine performance.

Typical L/D max for a sailplane is ~60:1. Typical L/D max for a Cessna 150 is ~7:1. Your glider is moving 60 feet forward for every foot of altitude lost. The Cessna 150 is moving 7 feet forward for every foot of altitude lost. It takes a lot less energy to move your glider than it does the Cessna.

Hence your glider has more power available in the turn. You will reach a point where you have exchanged all energy available and can no longer maintain that altitude. The Cessna on the otherhand will reach a point it can sustain performance at that altitude as long as it has fuel to convert to KE.

due to the different amount of lift generated by the wing.
Click to expand...

This statement bothers me and I just want to clarify your meaning here. Airfoils on different aircraft due generate different amounts of lift. However all of them generate only the amount of lift required for a condition of flight.

It does not matter what airfoil or lift devices you place on a 2000lb aircraft for example. It will always generate only 2000lbs of lift in level flight. In climbing flight our wing will generate less lift than in level flight and in a dive it will generate more lift than in level flight.

For example the roll rate has a major impact on how long it takes to get into a bank
Click to expand...

Yes, in fact designers consider roll rate to be much important than level turn ability. All manuvers begin with a roll.

Any aircraft with a significant roll rate advantage can use it to overcome a level turn advantage. Placing the vector of lift below the horizon adds weight directly to thrust based on the angle. Adding thrust to the turn equation directly increases our maximum sustainable load factor.

All the best,

Crumpp
 
Some aircraft have lift devices that enable them to reduce the turn radius
Click to expand...

The effects depend on the device in question. Flaps for example, depending on the setting selected will actually reduce turn performance. In the first few degrees the tendancy is too gain more lift benefit than drag penalty. After that first few degrees, the drag penalty increases explosively.

While TE or trainling edge flaps do increase an airfoils usable angle of attack by changing camber, they also increase the angle of incidence. This has the effect of lowering the nose of the aircraft while maintaining the capability to fly at a lower velocity for the same lift production. If we did not have flaps, our body angle at approach velocity would be high enough to obstruct the pilots view of the landing site.

Airfoil lift devices can be divided into two broad catagories. Those that increase camber, and those that energize the boundry layer.

As for the calculations, the effects are acounted for in the forces required.

All the best,

Crumpp
 
Just to clarify on the Zeke/P47 comparision.

Any turn that is below the blue line, the two aircraft will make exactly the same turn and the performance is sustainable.

Any turn above the blue line, the two aircraft will make exactly the same turn but the performance is not sustainable.

So if the Zeke is sustaining performance in an area the P47 cannot sustain the same performance, the P47 can exchange energy if available to match performance up to the stall line. This goes both ways for both aircraft.

Hnece the expression all aircraft at the same angle of bank and velocity will make exactly the same turn.

The graphs only show the thrust limited performance. There is a lift or stall line which is not shown. Niether aircraft can achieve controlled flight if they pass the stall line.

Understand now?

All the best,

Crumpp
 
I wasn't having a problem grasping the concepts
Click to expand...

Hi Bill,

I know that you do not have any trouble grasping the concepts. It is just a difficult concept to explain on a BBS over the internet.

I hope my explainations above make the concept I was conveying much clearer.

You are correct that there are situations where turn performance can be decisive. In fact turn performance is much more important in the Jet age due to the differences in thrust producers and power producers behavior in the region of reversed command.

It is an interesting line of discussion IMHO.

All the best,

Crumpp
 
I agree completely with Crumpp

The pilot is an extremely important factor, but taking away the pilot factor L/D T/D ratio, lift-loading and power-loading are the most important factors as to how well an a/c turns.

Believe it or not the Me-262 A-1a is actually a very capable turn fighter as long as the speed is kept high, and the extremely low drag of this a/c coupled with its high AR wing LE slats made sure it possesses a high L/D ratio, which means a much lower drag penalty for the amount of lift produced in aturn than normal - as its pilots explained the Me-262 was very slow to loose speed in a turn, which was very good cause if you did go slow you were in trouble as the acceleration of the jet-engines was very low at low speeds, making for a pathetic turn performance at low speed.
 
At 540 km/h at a weight of 6,000 kg the Me-262 A-1a will be capable of a 8 G turn, which is more than what the average pilot can take.

Lift: 1.58*21.7*.5*1.225*150^2 = 472503.938 Newtons (N)

472503.938 N = 48181.99 Kgf

48181.99 kgf / 6000 kg = 8.03033167

G-force at Clmax at 540 km/h: 8.03
 
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