Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: agent 009 on April 23, 2005, 10:56:50 PM
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Thought this might be of interest.
I have another graph from my retired pilot/Aeronautical Engineer, "Maximum Sustained Turn Rate" in terms of "Turn Rate in degrees/second." The values given are average turn rates - MSL through 30,000 feet. I would say that the plane with the greatest turn rate would be an indicator of an ability to cut a tighter turn. At the top, no surprise here, is the Spitfire LF Mk IX at 16 degrees/sec, followed by Spitfire Mk XIV at 15.3; P-38 J-10 at 13.5; Bf 109K-4 at 13; Bf 109G-6 at 12.8; P-51D at 12.8; Tempest V at 12.5; P-51B-10 at 12.5; Fw 190D-9 at 11.7; P-47M at 11; Fw 190A-8 at 10.9; and P-47D-23 at 10.5.
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K-4 ahead of G-6? interesting.
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Also 190D-9 ahead of A-8
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Dora stuff. Don't know how they got this data.
Turn Performance
300mph 1,000ft 5,000ft 10,000ft 15,000ft
One 360 17.9s 20.2s 23.2s 25.0s
Two 360s 39.7s 44.2s 53.1s 62.4s
250mph
One 360 19.4s 22.6s 26.8s 29.2s
Two 360s 41.4s 27.6s 58.0s 64.0s
Sustained
No Flaps 23.0s 25.5s 31.8s 38.4s
Full Flaps 23.7s 25.7s 32.4s 40.0s
Best Flap 1notch full none none
Speed/best 180mph 140mph 180mph 170mph
Corner Speed and Radii (1,000ft):
Speed: 325mph
Radius: 769ft
Sustained Turn Speed: 200mph
Sustained Turn Radius: 1,073ft
Full Flaps Speed: 155mph
Full Flaps Radius: 860ft
Corner Times 1,000ft 5,000ft 10,000ft 15,000ft
180 degrees 8.1s 9.2s 10.1s 10.5s
360 degrees 18.2s 20.3s 22.6s 24.1s
I did once read D-9 pilot's report. he said it could outturn A series as it had more shaft horsepower. Don't know what "shaft" horsepower means. But that's what he said.
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HP is usually measured at the engine shaft, as opposed to at the gearbox/wheels/prop/whatever.
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Originally posted by GScholz
Also 190D-9 ahead of A-8
And D9 and A8 ahead of P47s.
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Interesting. Perhaps you would like to share documents. I might have something of interest to trade.
I did once read D-9 pilot's report. he said it could outturn A series as it had more shaft horsepower. Don't know what "shaft" horsepower means. But that's what he said.
Adding more power will decrease your turn rate.
In a nutshell, Minimum level turn radius occurs at CLmax provided Pa = > Pr.
You can read more about it here on page 202:
http://www.enotalone.com/books/047168046X.html
All the best,
Crumpp
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The figures quoted by agent 009 looks like sustained turn rate data.
I did once read D-9 pilot's report. he said it could outturn A series as it had more shaft horsepower. Don't know what "shaft" horsepower means. But that's what he said.
In a sustained turn power-available (e.g. shaft horsepower etc.) is a key variable of turn performance since it's what's needed to offset the high induced drag and resulting power-required in a prolonged turn.
Tango, XO
412th FS Braunco Mustangs
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Well, I was looking for my graph of turn radius & couldn't find it. Did find this though.
He says he could "run circles" around the P-51 with the P-38. He has a lot of data on aircraft characteristics that back him up. For example, per a graph he, Woodrow, and I both have, "Comparative Turn Radius," the P-38 H's turn radius is 830 feet, and the P-51D's turn radius is 940 feet. This turn radius is with a 60 degree bank. With another graph, "Maximum Rate of Climb," the P-38J climbs at an average climb rate of 3,180 feet/min, and the P-51D at 2,790 ft/min.
Has anyone got a radius graph for rest of ww2 planes?
I think 109 F was 750
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Originally posted by Crumpp
Adding more power will decrease your turn rate.
Crumpp
Just to clarify this point... Adding more power will actually increase your sustained turn rate.
With more power available, a similar aircraft can sustain a higher turn rate, and for maximum rate turns at the load limit for either the pilot or the aircraft, the one with more power will lose energy less quickly and thus hold the higher turn rates longer. I think that’s what dtango is pointing out… He is correct.
You need to be careful here, because higher speeds are generally associated with lower turn rates and many people also associate higher power with higher speed, but at or below corner velocity it works the other way.
Hope that helps...
Badboy
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I think what Crumpp was trying to say was that if you increase power, you increase the TURNING RADIUS.
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(http://www.onpoi.net/ah/pics/users/503_1114374740_paequalspr.jpg)
Interesting Badboy. You are speaking of energy bleed and a turn rate increase due to speed. A pilot would just have to back off the throttle.
Adding Horsepower does decrease the turn radius.
For example, using this chart. Our theoretical aircraft is incapable of making a 60-degree bank at 125-130mph. Add 400 horses to the Pa and it can easily bank 60 degrees to tighten the turn.
Good example of this is both the Dora and the Spit XIV. Notice the Spit XIV when compared to the Spit Mk IX.
AFDU says:
The tactical differences are caused chiefly by the fact that the Spitfire XIV has an engine of greater capacity and is the heavier aircraft (weighing 8,400 lbs. against 7,480 lbs. of Spitfire IX).
AFDU says:
The turning circles of both aircraft are identical. The Spitfire XIV appears to turn slightly better to port than it does to starbord. The warning of an approaching high speed stall is less pronounced in the case of the Spitfire Mk XIV.
http://www.spitfireperformance.com/spit14afdu.html
http://www.spitfireperformance.com/griffonhp_b.jpg
The Spitfire Mk IX was limited to (+18) in the AFDU trials.
http://www.spitfireperformance.com/merlin66hpchart.jpg
All the best,
Crumpp
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Hi Crumpp:
Just for clarification turn rate and turn radius are two different things. Turn rate means how quickly you can get around the circle while radius is the size of the circle.
Usually increasing turn performance means (though not necessarily) that turn rate is INCREASING while turn radius is DECREASING.
When you say "tightening a turn" that means you're both reducing turn radius (size of circle) and increasing turn rate (how fast you get around the circle).
Tango, XO
412th FS Braunco Mustangs
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Doah!
Thank you Dtango and Badboy.
I did mean you increase your turn rate because your turn radius gets smaller.
I certainly know the difference between turn rate and turn radius. Just confused the wording as to whether increasing or decreasing is better for a fighter! :o
More power is a good thing....
All the best,
Crumpp
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Hi Agent,
>P-47M at 11
>P-47D-23 at 10.5.
Hm, I'd have expected the difference to be greater.
Assuming an altitude of 4500 m (which should be about right considering the data you quoted), my calculations would yield 10.5 °/s (Clmax set to match :-) for the P-47D-25 at 2535 HP/6621 kg, but 14.2 °/s for the P-47M at 2850 HP/6020 kg.
(Decreased weight and increased power seem to contribute at a similar order of magnitude to the improvement.)
Regards,
Henning (HoHun)
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Originally posted by lasersailor184
I think what Crumpp was trying to say was that if you increase power, you increase the TURNING RADIUS.
That isn’t true either, but it doesn’t really matter now, because it looks as though the penny has dropped. The thing to remember is that increasing power doesn’t automatically mean an increase in turn radius, because the turn radius depends on the speed and the load factor, it wouldn’t matter if you were in a power off glide or at full power, the same combination of speed and load factor would produce the same turn radius.
Once again, it is easy to think along the lines that higher power implies higher speeds, which would in turn lead to larger turn circles, but that is not necessarily so, because even at full power aircraft can still fly slow enough for minimum radius turns.
Hope that helps...
Badboy
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Originally posted by HoHun
Hi Agent,
>P-47M at 11
>P-47D-23 at 10.5.
Hm, I'd have expected the difference to be greater.
I would have though so too.
Since I'm involved in dynamic testing almost on a daily basis (not of aircraft), my experience is that a sample of one is meaningless.
If the USAAF takes out one of every type (as they usually did), and several pilots fly different aircraft, the results will be skewed towards the skill of the individual pilots, which even among test pilots can vary widely. Even speed runs can vary quite a bit depending upon state-of-tune and fit and finish of the aircraft.
We see this in the game. One guy can turn a fighter tighter than another guy (flying the same model with a similar loadout).
To get truly accurate measurements of performance, a significant population would have to be tested. This is something that AFDU, TAIC and the USAAF did not do. They usually tested one or two aircraft.
Everything is relative and comparison testing has far too many uncontrolled variables to be considered gospel.
My regards,
Widewing
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If an aircraft which goes the circle in a given time will get more thrust without a weight penalty, it will definately be able to turn tighter.
This is basic.
The Spit XIV, being heavier than the IX for instance, could practically keep up with it's older-of-kin, while being heavier, the remedy was more power.
The 109F may have been a tad heavier than the 109E, yet it turned better if anything!
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Originally posted by Widewing
I would have though so too.
Since I'm involved in dynamic testing almost on a daily basis (not of aircraft), my experience is that a sample of one is meaningless.
If the USAAF takes out one of every type (as they usually did), and several pilots fly different aircraft, the results will be skewed towards the skill of the individual pilots, which even among test pilots can vary widely. Even speed runs can vary quite a bit depending upon state-of-tune and fit and finish of the aircraft.
We see this in the game. One guy can turn a fighter tighter than another guy (flying the same model with a similar loadout).
To get truly accurate measurements of performance, a significant population would have to be tested. This is something that AFDU, TAIC and the USAAF did not do. They usually tested one or two aircraft.
Everything is relative and comparison testing has far too many uncontrolled variables to be considered gospel.
My regards,
Widewing
I think you're absolutely right about that. Those spreads would have been even bigger in those days, without the better tolerance systems that we have today. Sometimes I wonder what they would be like if those designs were manufactured with todays systems, being truer to the design than was possible then. I have few engineers, machinists, and a tool&die wizard in the family, and they make it sound alot more like gambling when it came to fitting those machines in those days.
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Agree results vary. Atmoshperic conditions are different in UK, Germany & US. Plus if a country flys a captured aircraft, it can be an old flown out one. German pilots got more out of D-9 than US pilots did after war when asked to fly it. So familiarity plays a pivotal role. How to use tail trim device etc.
Also, I don't know what altitude the graph above was calculated at.
Leykauf said it mattered how one "went in" to a turn, so pilot skill is all important to how well a plane turns.
& yah Crump, anything you wanna trade feel free.
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What is your email addy?
All the best,
Crumpp
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Me? elephantshampoo@yahoo.com
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Agent,
I am always curious about different peoples turn estimate calculations mostly because we assume they start out with good data.
I think I emailed you a turn performance calculator from an engineering student that used to be on these boards. You can plug many variables into it and come to your own conclutions.
The most mistated performance characteristic of WW2 A/C I have seen is clmax. If that is wrong you are done before you start. After that make sure the weight is correct followed by HP, Wing area and span.
The best indication of trun performance is stall speed in level 1G flight. If you have that information from the A/C pilots manual you can quickly calculate Clmax and get your answers from there.
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Well, I suck at math, but will give it a go.