Chart of Stall Speed vs G

[pembquist]

Has anyone made a performance chart with stall speed at G 1-6 (or structural failure if that is higher than 6)?  I'm just learning in the Spit 8 and it occurred to me that I want these numbers.  I can test fly but I thought for all the other planes someone might have done some research.  (Isn't it just part of the computer code anyway?)

[Drano]

I haven't seen charts like those you describe for the AH planes although there are performance curves available for speed and climb rate at a given altitude. I'm sure the turn rates are part of the code as that would have to be a fairly important component of the flight model. I see you're looking for G 1-6 as I'm sure you understand that 6G is the point at which you would black out within a few seconds. That's a constant. Structurally, yeah they're all different and that would also be part of the models and another constant. That plane would start to break apart at a certain stress level every time. You know the performance numbers would be impacted by configuration of the aircraft and also by the altitude? The weight of things like fuel, bombs and ammo, whether you're using flaps, etc., would all impact turn performance. A piston engine might generate more power at one altitude than another affecting power to weight ratio again affecting turn rate. Some planes that are beasts below 15K are all but useless above 20K. That said there is no set in stone number (other than the structural limits) regarding turn rates as it's all relative to the variables above. The turn rate charts you're looking for, if you look closely, are performance numbers for a particular aircraft using a particular configuration at a particular altitude. They would be accurate but only for those parameters.

[pembquist]

What I'm curious about is at what airspeed you can pull a given g-force without stalling.  At gross weight, (whatever that is in AH,) lets say.  This would be the same, (if the airspeed indicator is modeled on pitot/static pressure like a real altimeter,) no matter the altitude.  I'm confusing myself the more I think about it but I was thinking that a 6 g turn at minimum airspeed would be the fastest reversal of direction.  A slower speed would have a tighter turn radius I guess, but I'm thinking degrees/second would be less in a level turn.  I could be all wrong,(not about the g airspeed altitude thing though.)

[pembquist]

What I'm curious about is at what airspeed you can pull a given g-force without stalling.  At gross weight, (whatever that is in AH,) clean configuration.  This would be the same, (if the airspeed indicator is modeled on pitot/static pressure like a real altimeter,) no matter the altitude right?  The same way True Air Speed goes up compared to Indicated AS as you gain altitude.  I'm confusing myself the more I think about it but I was thinking that a 6 g turn at minimum airspeed would be the fastest reversal of direction while maintaining velocity.  A slower speed would have a tighter turn radius I guess, but I'm thinking degrees/second would be less in a level turn.  I could be all wrong,(not about the g airspeed altitude thing though.)

[Rolex]

The slowest speed that you can still pull 6 G's is called "Corner Speed" or "Corner Velocity." That is an instantaneous turn and not a sustained turn, so your turn rate degrades quickly.

The speeds for each plane are derived from testing, then input into a spead sheet or an EM Diagram. The test conditions are usually 25% fuel, 500' AGL, flaps (settings vary) and no flaps, +/- 50' altitude variation, a set fuel burn for the game, stall limiter off, combat trim off and other flight parameters by the person testing. It also depends on who is doing the testing, but the numbers don't vary too much if the same test conditions are followed.

Here is some data of sustained turn as tested by MOSQ. (Disclaimer: I don't know if it has been updated beyond this link.) Lnk>>

[Drano]

What Rolex says about instantaneous vs sustained turn rates is spot on. If you're looking for the "max" turn rate that rate might only be able to be maintained briefly--maybe only a second or less. Looking at an actual EM diagram you'll see a peak at the low speed and high speed ends at the 6g line. There's a reason for the peak. On the low end (with a higher peak, indicating a higher turn rate) as soon as you start to pull in the turn you'll induce drag onto your plane and you'll slow down. As soon as you slow down--even a little--you're no longer turning at that max rate. The sustained turn rate is the maximum rate of turn a plane can generate for an *extended* period of time--but that's not going to be at 6gs in a propeller driven aircraft. On the high end (with the lower peak) the reason is with the higher speed you're turning a larger radius and slower turn rate. You've got the concept of higher speed= larger radius and slower turn rate. Just know that slower and slower might = a tighter turn radius but not necessarily a faster turn rate. The reason there's a curve along the 6g line is it's rather pointless to discuss turn rates higher than that as, at least within the game's model, you're blacked out and in no position to enjoy it.

Seems you're on the right track. I'd suggest doing a search for posts in this forum by a guy named Badboy who can explain this subject in greater detail than I'm capable of.

I'd also suggest that there's more to this game than turning. Yanking away will put you at a disadvantage more often than not vs a competent pilot. Best to know when to turn and when not to turn.

[Drano]

Here's a link to one of Badboy's EM diagrams that might help. Be advised it's a little dated and the FM has been tweaked since that time so don't use it as dogma but more as a guide. Pay attention to the peaks representing max turn rate and sustained turn rate. See there's a difference in both even tho they're both Spits. Different models with different performance.

The turn rate curves for every plane ever would look much like this.

http://bbs.hitechcreations.com/smf/index.php/topic,164617.0.html

[Drano]

And more of Badboy's goodies. I was shocked to see these still up! Again pay attention to the dates--ancient. While the data might not be useful today, the concepts remain the same.

http://bbs.hitechcreations.com/smf/index.php/topic,83992.0.html

Scroll down about 2/3's through this thread to a reply by Badboy to FTJR. There are links to some .pdf files there that are excellent.

[Drano]

Read this whole article.

http://www.simhq.com/_air/air_011b.html

[Rolex]

Here is the easy way to derive corner velocity: multiply clean stall speed of the aircraft by the square root of 6 (2.45)

If a Spit VIII stalls at 90 MPH clean, corner velocity is 90 x 2.45 = 221 MPH.

[pembquist]

Excellent information.  I'm brand new at AH and I'm really glad I didn't get the rtfm response. Rolex can I ask where the cornering formula comes from? Thanks all.