Author Topic: Turn rate and radius questions (Read 4019 times)

F4UDOA · « **Reply #15 on:** April 24, 2003, 09:39:32 AM »

TimRas,

I don't by any means put 100% into these types of evaluations.

However I don't completely disregard them either. When I read that even though it sounds overstated I think based on wing loading and the known higher stall speed of the 190 that the F4U would have a turning advantage. I would like some clear data on accelerated stalls for the 190 series which I do not have. I do have many German docs on the 190 but I can't read them and I don't know if stall speeds are even listed.

So based on this

1. Navy evaluation.

2. 1G stall speeds.

3. Wing loading

4. Zigrats spreadsheet

I think I can make a case for some innaccuracy for the relative turning performances in AH.

Tilt · « **Reply #16 on:** April 24, 2003, 10:28:04 AM »

Quote

Originally posted by F4UDOA
CC Zig,

I have had an ongoing conversation with HT about stall speeds. There are two others that are off for sure. The F6F and P-38.

Can you add both of AH's Lavochkins to this. Pilots notes show an advised landing speed of 85 miles / hour (137km/hour).

In AH the plane has already fallen out the sky at this speed suggesting 1 g stall at least is high.

Its possible that the slats are not modelled (extending between and then below 220/200 km/hour)

dtango · « **Reply #17 on:** April 24, 2003, 10:52:44 AM »

Quote

The F4U-1D has a 3G stall of approx. 160MPH and the FW190A5 3G stall of Approx 190MPH.

Why is it not possible for the F4U to sustain a 3G turn of say 170MPH (10MPH above it's instentanious turn rate) and simply turn well inside the 190?

Because you can't hold 3G's at 170 MPH for any length of time in a flat turn. The a/c bleeds E in a turn so maybe you could get 1-2 sec of 3G's as the speed decays to 160MPH. Let's say you continue the flat turn after you reach 160MPH. You would have 2 outcomes - (1)If you tried to maintain 3G's in a flat turn you would stall. (2)If you wanted to maintain a flat turn and remain in flight your turn performance would have to decrease along with the continued decay of airspeed.

Tango, XO
412th FS Braunco Mustangs

Badboy · « **Reply #18 on:** April 24, 2003, 11:23:38 AM »

Quote

Originally posted by F4UDOA
BTW Zig,

Are the EM diagrams sustained or instantanious?

The diagrams give both sustained and instantaneous performance. I've labled the previous diagram so that you can see which curves represent the sustained turns and which ones are instantaneous. Here it is:

Badboy

F4UDOA · « **Reply #19 on:** April 24, 2003, 11:33:12 AM »

Dtango,

Ok, I understand.

But every A/C has a best sustained turn rate.

According to Zigs spreadsheet the F4U should be able to have a sustained turn of 165MPH at 18.86DPS and the FW190A5 best sustained turn should be 185MPH at 17.55 DPS.

This gives best sustained turn times.

12,000lbs F4U-1D full turn time = 19.33secs/2.7G's/radius 744.5FT

8,690Lbs FW190A5 full turn time = 20.5secs/2.8G's/radius 897FT

So there is a clear advantage.

In reality what would happen is both pilots pull beyond max sustained and both slow down.

The F4U has again a greater ability to turn at lower speeds so the harder the pull the more this should favor the F4U.

Also in reality these speeds would be lower because he cl max used in these calc's is not based on full power prop wash over the wings which greatly increase prop wash and lowers stall speeds.

Badboy · « **Reply #20 on:** April 24, 2003, 11:46:01 AM »

Quote

Originally posted by F4UDOA
Dtango,

Let me re-phrase my question.

The F4U-1D has a 3G stall of approx. 160MPH and the FW190A5 3G stall of Approx 190MPH.

Why is it not possible for the F4U to sustain a 3G turn of say 170MPH (10MPH above it's instentanious turn rate) and simply turn well inside the 190?

If we take the performance of the AH F4U-1D and Fw190-A5 from the EM diagram I posted earlier, and use that to predict the outcome of a one and two circle fight for the F4U-1D if it sustains a turn at 160mph and the Fw190-A5 if it sustains a turn at 190mph the situation would like this...

And this... Here you can see that the F4U-1D would get a guns opportunity in less than half a turn, so you can see it isn't just the turn rate that is important, because you can see from the diagram above, that their turn rates are not very different, but you also see from the diagram below, that the difference in turn radius is really responsible for the early shot, depending on which way they turn.

Of course, in this example, although the Fw190 is pulling a sustained turn at 190mph, it isn't pulling its best sustained turn, it isn't max performing. I used the speed you quoted, just as an example.

It is also worth noticing from the EM diagram that the 3g stall speed for these aircraft are instantaneous values, not sustained because they are above the sustained (Ps = 0) turning curve.

Some food for thought there

Hope it helps.

Badboy

F4UDOA · « **Reply #21 on:** April 24, 2003, 11:54:02 AM »

BadBoy,

I realized my error when examining the charts. Thanks for the explanation.

However I noticed two things when examining your chart compared to the G limits chart i posted.

1. Notice the 2G intantanous from AH and the real chart. The 2G stall should be about 10 to 15MPH lower.

2. You are testing with 25% fuel. This chart is for max internal load. So basically a F4U-1D in AH with 25% fuel stalls higher than a RL F4U-1D with full fuel.

Frankly I don't don't know why I am so interested considering I hardly get a chance to play more than a few hours a month. I am far more interested in the historic performance than I anything else.

Thanks for the input

F4UDOA · « **Reply #22 on:** April 24, 2003, 11:59:34 AM »

Heya,

You keep beating me to the punch getting your post in a second sooner.

I ask you, does it seem like there is an extreme parity in the turning ability of A/C in AH compared to RL?

I can't help but wonder if this is not intentional for gameplay?

Badboy · « **Reply #23 on:** April 24, 2003, 12:14:47 PM »

Quote

Originally posted by F4UDOA
Dtango,

Ok, I understand.

But every A/C has a best sustained turn rate.

According to Zigs spreadsheet the F4U should be able to have a sustained turn of 165MPH at 18.86DPS and the FW190A5 best sustained turn should be 185MPH at 17.55 DPS.

This gives best sustained turn times.

12,000lbs F4U-1D full turn time = 19.33secs/2.7G's/radius 744.5FT

8,690Lbs FW190A5 full turn time = 20.5secs/2.8G's/radius 897FT

So there is a clear advantage.

But that is only a small advantage, just over one degree per second difference, and not very different to the test times you posted in your original message, and not very different from the AH EM diagram above?

Badboy

F4UDOA · « **Reply #24 on:** April 24, 2003, 12:31:34 PM »

Those numbers are from the spreadsheet EM that Zig gave me.

Badboy · « **Reply #25 on:** April 24, 2003, 12:33:23 PM »

Quote

Originally posted by F4UDOA
Heya,

You keep beating me to the punch getting your post in a second sooner.

Yep, perhaps I type faster than you

Since we are both just sat at our keyboards, why not email me a voice number (Badboy@netcomuk.co.uk) so we can chat... my dime

Quote

I ask you, does it seem like there is an extreme parity in the turning ability of A/C in AH compared to RL?

Well, of course some aircraft appear to be similar, but others are very different so I don't think you have discovered a trend. But when you consider that it is almost impossible to find any two real world sources that agree on such data, we shouldn't be too surprised to find that the sources used in AH doesn't match what you have.

Quote

I can't help but wonder if this is not intentional for gameplay?

I doubt that very much! I have no doubt at all that every aircraft in the game represents an honest and honorable attempt to model it with the maximum fidelity possible. I've been flying simulations since 1987, and I've flown every online sim ever produced, and I can say without doubt that HTC have certainly shown more commitment to getting it right, and willingness to tweak, than any other developer I've known. In most cases I think they have done an excellent job. My guess is, that if you really want to influence their effort, this might not be the best place to do it

Badboy

Badboy · « **Reply #26 on:** April 24, 2003, 12:37:43 PM »

Quote

Originally posted by F4UDOA
Those numbers are from the spreadsheet EM that Zig gave me.

Sorry, I'm getting confused

Badboy

Zigrat · « **Reply #27 on:** April 24, 2003, 01:02:51 PM »

dude my spreadsheet is just approximate mabye accurate to 10% but not exact. i wrote that thing a long time ago when i really didn't know much, i still don't know a lot but definitely more than i did then, i just had to study performance fo my qualifying exams.

Zigrat · « **Reply #28 on:** April 24, 2003, 01:04:39 PM »

i have a little time today i am gonna look at that thing and see if i can improve it

dtango · « **Reply #29 on:** April 24, 2003, 01:54:29 PM »

F4UDOA:

(1) You mentioned the best sustained turn performance #'s from Zig's spreadsheet. Badboy points out how small a differential of an advantage that is.

(2) If you look at Badboy's EM chart you'll notice best sustained turnrates and radiuses of both a/c are even closer and pretty much negligible vs. the data you quoted from Zig's worksheet.

(3) Hopefully you can see by all this that comparative turn performance can be extremely tricky to determine between a/c because if you want to compare apples to apples there all sorts of things that you need to take away as variables. Badboy's further explanation of sustained turns using the speeds of F4U at 160mph vs. Fw190A5 at 190mph is an example. At those speeds according to Badboy's charts the F4U will gain angles on the 190A5. The reason being the F4U is flying at a point of it's flight envelope that has better turn performance than the 190A5. But this isn't an apple to apple comparison. Looking again at Badboy's chart you'll notice that the 190A5 if flown in a sustained turn maintaining 160 mph would pretty much match the F4U's turn rate and radius.

(4) Looking at Badboy's EM chart again the F4U doesn't have much if any advantage for sustained turns at slower speeds.

(5) If you were at Ps=0 and lowest airspeed for Ps=0 you couldn't pull any harder without stalling or losing alt.

Tango, XO
412th FS Braunco Mustangs