Sustained Turn Ratio vs IAS measurements

[artik]

On the deck 50% fuel (P-51D 25%), WEP+

360 degree turn time in seconds:

Plane	200mph	250mph	300mph
Yak-3	19.5	23.2	31.9
Spit 14	19.2	23.0	30.6
La-7*	21.2	22.5	28
109K	22.7	26.0	30.1
P-51D	21.9	25.2	33.8

* Not too accurate

It is damn hard to keep speed and altitude constant. In most of cases alt +- 50 feet speed += 10mph

[artik]

Added G force and turn radius


Plane   200mph                  250mph                   300mph
---------------------------------------------------------------------------
        t       G       R       t       G       R       t       G       R
---------------------------------------------------------------------------
Yak-3   19.5    2.95    280     23.2    3.1     410     31.9    2.7     680
Spit 14 19.2    3.0     270     23.0    3.1     410     30.6    2.8     650
La-7*   21.2    2.7     300     22.5    3.2     400     28      3.1     600
109K    22.7    2.5     320     26.0    2.7     460     30.1    2.9     620
P-51D   21.9    2.6     310     25.2    2.9     450     33.8    2.6     720


t - time of 360 turn seconds
G - G-load
R - radius of turn - meters


I'll try to add more in near future and refine measurements I can

[hitech]

artik, what are you measuring at speed? Trying to maintain the same speed in the turn?

Or are you starting at a speed, and doing 1 360 turn?

HiTech

[artik]

Ohh this is hard

I do left turn low over the water so I have good visual height reference.

I keep E6B open to see the speed and I try to maintain it as constant as possible while also keeping altitude.
It is very hard and in general I manage to keep the speed +- 10mph and alt +-50 feet - for La7 I didn't do it so well that it is marked by *

All is done using AHF recording. I do several circles. Than in AHFV I measure time for each circle and than take an average.

I don't always succeed but it is the best I can manage. I assume test pilots can do it better - I'm still learning to be AH2 test pilot 

It would be cool to have offline autotrim on sustained turn ratio :-)

Edit: I can attach a link to sample test if you want.

[earl1937]

Added G force and turn radius


Plane   200mph                  250mph                   300mph
---------------------------------------------------------------------------
        t       G       R       t       G       R       t       G       R
---------------------------------------------------------------------------
Yak-3   19.5    2.95    280     23.2    3.1     410     31.9    2.7     680
Spit 14 19.2    3.0     270     23.0    3.1     410     30.6    2.8     650
La-7*   21.2    2.7     300     22.5    3.2     400     28      3.1     600
109K    22.7    2.5     320     26.0    2.7     460     30.1    2.9     620
P-51D   21.9    2.6     310     25.2    2.9     450     33.8    2.6     720


t - time of 360 turn seconds
G - G-load
R - radius of turn - meters


I'll try to add more in near future and refine measurements I can

Good post! I would like to see your measurements of constant 3G turns, at constant altitude. Airspeed is going to decay somewhat when first entering turn, but after a constant 3G, speed should stabilize, as we have no heat thermals or wind to content with in AH2. (assuming a 500 foot altitude).

[artik]

Good post! I would like to see your measurements of constant 3G turns, at constant altitude. Airspeed is going to decay somewhat when first entering turn, but after a constant 3G, speed should stabilize, as we have no heat thermals or wind to content with in AH2. (assuming a 500 foot altitude).

There are two major problems with a constant 3G.

1. If you take a look on the typical G vs Speed you'll see that at some point G grows with the speed and than goes down  to 1G at the top speed. So every G non-peak value has two sable points - low speed and high speed.

2. It is much harder (at least in AH) to maintain constant G turn. There are two ways to measure it while flying: (a) by using G-meter - but is has very low accuracy - its notches are about 1/2 G. (b) Use constant angle of wings related to the horizon actually G = 1/cos(alpha)  where  alpha is the angle between the horizon and the wings. But it does not have accurate measuring instrument as well. Additionally as G grows the changes in alpha become much smaller  making it is even harder to keep the constant G. For example the difference between 2 and 2.5G are about 6 degrees and 2.5 and 3.0G is 4 degree -  barely visible

On the other hand, altitude and speed have very accurate gauges. For speed we have both accurate altimeter and variometer while the speed has quite accurate gauge and up 1mph accurate E6B as well.

The turn speed can be measured with stopper easily

This makes constant speed/altitude turn speed measurement much easier (but still very hard:

This is one of the test films Yak-3 250mph sustained speed: http://cppcms.com/files/yak3-250.ahf

You can see that it is very hard to keep the steady flight parameters and they fluctuate.

[bustr]

The game's E6B is an interface in real time reveling the active data sets Hitech chose to make available. He could have made this available as another HUD like the damage list or FPS counter. Since so many players over the years have spent countless hours offline attempting to manually create speed, climb and turn rate charts a la Wright Bros and a stopwatch.

You could ask Hitech for an "offline only" HUD like tool to assist you in gathering more accurate data. I suspect for development and testing Hitech has a developer mode with everything you would ever want to see in an active HUD display along with logs to review. OR, Log Mode in which you use hot keys to start and stop active logging while you pull turns, climb and fly speed tests. OR, Hitech could make that a component of the film viewer so you can playback in data mode along with generating a log file to build your speed, climb and turn charts from.

It couldn't hurt since these ongoing efforts may be a passive trouble shooting vector that helps Hitech keep track of his aircraft physics modeling visa watching the forum. Worst case, more forum fights over "my data is better than your data".

[earl1937]

There are two major problems with a constant 3G.

1. If you take a look on the typical G vs Speed you'll see that at some point G grows with the speed and than goes down  to 1G at the top speed. So every G non-peak value has two sable points - low speed and high speed.

2. It is much harder (at least in AH) to maintain constant G turn. There are two ways to measure it while flying: (a) by using G-meter - but is has very low accuracy - its notches are about 1/2 G. (b) Use constant angle of wings related to the horizon actually G = 1/cos(alpha)  where  alpha is the angle between the horizon and the wings. But it does not have accurate measuring instrument as well. Additionally as G grows the changes in alpha become much smaller  making it is even harder to keep the constant G. For example the difference between 2 and 2.5G are about 6 degrees and 2.5 and 3.0G is 4 degree -  barely visible

On the other hand, altitude and speed have very accurate gauges. For speed we have both accurate altimeter and variometer while the speed has quite accurate gauge and up 1mph accurate E6B as well.

The turn speed can be measured with stopper easily

This makes constant speed/altitude turn speed measurement much easier (but still very hard:

This is one of the test films Yak-3 250mph sustained speed: http://cppcms.com/files/yak3-250.ahf

You can see that it is very hard to keep the steady flight parameters and they fluctuate.

Ok, one fact that you cannot get away from is this: If you go into a turn and establish a 3G turn, 2 things are going to happen: #1 unless you add power during the turn, the airspeed is going to decay! #2- unless you add power to maintain your desired airspeed, then the AOA will be constanty changing in order to maintain your altitude. The only way to do the tests, as I see it, is to go into the turn at say, 75% power, using the other 25% to adjust your airspeed as it decays and or to hold your altitude. In straight and level flight, you are pulling 1G, in a 30 degree bank, 1.5G's and a 60 degree bank, 2G's, so you are going to have to start with a 90 degree bank and back pressure on the "stick" to get to the 3G factor and without adding power, your altitude and airspeed are going to be decaying during the whole turn. But, thanks for sharing what you did with us!

[Widewing]

There are two major problems with a constant 3G.

1. If you take a look on the typical G vs Speed you'll see that at some point G grows with the speed and than goes down  to 1G at the top speed. So every G non-peak value has two sable points - low speed and high speed.

2. It is much harder (at least in AH) to maintain constant G turn. There are two ways to measure it while flying: (a) by using G-meter - but is has very low accuracy - its notches are about 1/2 G. (b) Use constant angle of wings related to the horizon actually G = 1/cos(alpha)  where  alpha is the angle between the horizon and the wings. But it does not have accurate measuring instrument as well. Additionally as G grows the changes in alpha become much smaller  making it is even harder to keep the constant G. For example the difference between 2 and 2.5G are about 6 degrees and 2.5 and 3.0G is 4 degree -  barely visible

On the other hand, altitude and speed have very accurate gauges. For speed we have both accurate altimeter and variometer while the speed has quite accurate gauge and up 1mph accurate E6B as well.

The turn speed can be measured with stopper easily

This makes constant speed/altitude turn speed measurement much easier (but still very hard:

This is one of the test films Yak-3 250mph sustained speed: http://cppcms.com/files/yak3-250.ahf

You can see that it is very hard to keep the steady flight parameters and they fluctuate.

It takes a lot of practice to get good at sustained turning. Like Mosq, I've tested everything. With few exceptions, we usually get numbers that are very close.

Now, here's a tip towards making it much easier to test the Yaks... Turn right instead of left. By going right, you're not fighting torque and you'll have less trouble being consistent.

[Karnak]

Now, here's a tip towards making it much easier to test the Yaks... Turn right instead of left. By going right, you're not fighting torque and you'll have less trouble being consistent.

Spit XIV, Tempest and Typhoon as well.

[artik]

One other thing I thought of is to create several areal circles that are very easy to follow - such that you would have an exact flight path you can follow without looking that the gauges.

Maybe some sort of torus sharped cloud with big radius but very thin - something like that.

Such that you fly at constant=alt/turn-radius on full power and see at what speed you get stabilized.

Is there any way to create such a circular path that would be easily visible by the pilot?

[Mace2004]

Hummmm...not meaning to dismiss your good work artik but why not just use the EM diagrams Badboy (and I think some others) produce?  You can read all that info (and more) directly off the chart.  This chart has the P-51D and Yak-9U (sorry, couldn't find a copy with just the Pony.)  

To use this for a stabilized level turn (i.e., constant speed, constant G), just pick your speed at the bottom and then go vertically to the P_s=0 line.  From that point you look across to the left and you can read the Degrees per Second (DPS).  Follow the curved G line to determine your available G and follow the diagonal lines to determine radius.  

So, for the P-51D at 200mph with 25% fuel, at sea level and mil power we get: 17DPS, 2.8G and 1000ft radius.  Convert that to a 360 degree turn and meters and you get 21.2 sec for a 360deg turn at 2.6G with a radius of 304 meters.  Also, as others have asked regarding numbers associated with a specific G, the chart can do that as well.  Let's pick 3G.  Follow the 3G line to where it intersects the P_s=0 line (ok, it's just a tiny bit away from intersecting but close enough for government work) and we get 250mph.  Degrees per second is 14 (25.2 sec for 360deg) with a radius of 1,500 ft (457 meters).  

These charts can also tell you lots more.  For instance, you can't sustain a level turn above 3G at all (it's all above the P_s=0 line so you don't have enough power to sustain a level turn above 3G).  Also, if you're at full power at a constant 2g level turn you'll accelerate to about 345mph (you're below the P_s=0 line so you have excess Power).  You can also lots of other things, for instance your available instantaneous turn rate anywhere in the envelope (23DPS at 325mph with a 1200ft turn radius) and lots more...it's like magic!  It's not only easier than doing a flight test for every number you'd like to know there's no math required.

All that said, there really isn't much use for numbers like constant speed and G other than where they are maximized.  In ACM you always strive to maximize your plane's performance either in acceleration or turns so these "in between" numbers aren't as useful as say, corner and max sustained speeds.  Generally speaking, you're either trying to accelerate in a straight line or using your maximum performance instantaneous or sustained turn rates.  If you aren't max performing your turns you increase your radius (called "arcing").  Arcing will often give your opponent an advantage as he can more easily position himself within your turn radius to cut you off or lead turn you.  That said, it's certainly interesting and beneficial to study these types of performance numbers as they show you the tradeoffs you make when you don't max perform your plane.

[artik]

Nice, that is what eventually I wanted to have (I was searching for something like that but hand't found).

Questions:

- Were do I get these diagrams/data?
- How they had they been generated?
- Are there similar diagrams for different altitudes?

BTW what is cool that I got relatively close data using flight testing...

[pervert]

http://www.leonbadboysmith.com/Files/AH_BootStrap.zip

Think thats what you are looking for Badboy's Bootstrap Calc?

[FLS]

Artik the turn rate data comes from flight testing. It's very difficult to get it exactly right but you only need to get close to have useful information.
 
Typically for best sustained turn you'll be pulling between 2.5 and 3 Gs at the slowest speed which allows that G load. You can pull harder and go slower but you won't turn as fast. You can see that on the EM diagram. Sustained turn rate peaks at 170 mph for the P-51 and 160 mph for the Yak. Going slower drops the turn rate as does reducing G load.

You won't know if you want 2.5 or 3 Gs or something in between until you fly it and time it. The speed and G combination that gives you the best sustained turn rate in a particular WW2 fighter aircraft will likely be more than 2.5 G and slower than 200 mph. If you see 2.8 G and hear the stall horn you're likely close to your best turn.

It's useful to go faster than your best sustained turn speed so that you have energy for vertical maneuvers.  If the bandit gets too slow from max turns he won't be able to follow you up.