Roll Rate study

[Noah17]

Does anybody know of studies done to measure the roll rate's of different WWII aircraft?

[JOACH1M]

Does anybody know of studies done to measure the roll rate's of different WWII aircraft?

190 had the fastest of the war

[Noah17]

I believe it (190) did but I would like to be able to compare a bunch of different aircraft. F4U, A6M, P38, 109......etc...

[JOACH1M]

I believe it (190) did but I would like to be able to compare a bunch of different aircraft. F4U, A6M, P38, 109......etc...

I heard that the A6m out rolled f4f's and that the hellcat could outroll Georges

[pervert]

Might be wrong but I think its measured in time to roll a set amount of degrees, obviously speed would also have to be factored in. I'm sure there is a way to do a chart for it badboy might know how to do something like this  How you would obtain an accurate measurement in game for the varied speed range is beyond me 

[oboe]

I heard that the A6m out rolled f4f's and that the hellcat could outroll Georges

I think pervert is right, speed is definitely a factor.  The A6M probably could outroll the F4F at low speed (I think the Zeke's ailerons had a larger surface area) but at higher speeds the large ailerons became a disadvantage because it took more pilot strength to operate them.   Think I heard or read that somewhere.   

Also I think the P-38L had a very good high speed rollrate due to hydraulic assist.     

[IrishOne]

http://www.wwiiaircraftperformance.org/naca868-rollchart.jpg


this should help 

[SmokinLoon]

http://www.wwiiaircraftperformance.org/naca868-rollchart.jpg


this should help 

I was just about to post a link to that.   

That chart shows the real deal.  Funny how speed changes the rate of roll for certain planes, eh?  Most people forget that.  Likewise, most people forget that planes turn differently at different speeds.  Many of the stereotypical "bad" turning aircraft turn just as good if not better at high speeds than some of the best slow speed turners.

[LLogann]

Yup.... Even the Flying Brick A8........ 

190 had the fastest of the war

Forget about RL.... None of that matters........  Longer you're here the more you fly different rides, you'll soon know yourtself what you prefer to Roll in............

Me?  I prefer to roll with lots of water and a few cuties, in a private home, not in public.   

[hitech]

I was just about to post a link to that.   

That chart shows the real deal.  Funny how speed changes the rate of roll for certain planes, eh?  Most people forget that.  Likewise, most people forget that planes turn differently at different speeds.  Many of the stereotypical "bad" turning aircraft turn just as good if not better at high speeds than some of the best slow speed turners.

In general , roll rate varies linearly with true air speed for any given plane. I.E. you roll twice as fast with twice the speed.

This remains true until the pilot becomes stick force limited.
The wings begin to twist do to high forces.
The control surface begins to bend or deflect.
The cables begin to stretch do to high forces.

The easiest way to think of rolling is simply viewing a screw/helix threw the air. No mater how fast you are going your wing tips remain in the same helix. Hence it must roll faster/slower with change of speed.

HiTech

[Oldman731]

The easiest way to think of rolling is simply viewing a screw/helix threw the air.

I went to one of those, once.

- oldman (smiles at the memory)

[pervert]

Hitech I take it your example assumes that the pilot is always using full airleon to roll?

[bozon]

Hitech I take it your example assumes that the pilot is always using full airleon to roll?

You only need to assume a given constant aileron deflection while the speed varies. Full deflection is such a case as long as the other factors HT mentioned allow this to stay constant.

[dtango]

Hitech I take it your example assumes that the pilot is always using full airleon to roll?

It doesn't matter what the aileron deflection is, roll rate always increases with increasing airspeed up to the constraints HT mentions.

For a steady roll (constrained to a single degree of freedom) the roll rate equation is:


where

V = velocity
b = wing span
Clalpha_a = rolling moment coefficient due to ailerons
Clp = rolling moment coefficient due to rolling (also known as roll damping moment)
delta_a = aileron deflection angle

What the NACA 868 chart shows us is what happens when aileron deflection angle is limited by 50 lbs of stick force.  At higher speeds dynamic pressure is greater thus it requires more force to deflect the aileron a given set of degrees.

Here's an old post I put up awhile back if you're interested in more of the physics of a roll:
http://bbs.hitechcreations.com/smf/index.php/topic,253393.msg3138691.html#msg3138691

[pervert]

You only need to assume a given constant aileron deflection while the speed varies. Full deflection is such a case as long as the other factors HT mentioned allow this to stay constant.

That makes sense to me   dtango great post i'll have to some more reading up on that link you posted thanks guys