Air Warrior Turn Performance Diagrams

These GIF files depict the energy-maneuverability (E-M) characteristics of Air Warrior's WWII prop fighters (at least as much as I could generate from the data in the AW manual ). E-M diagrams depict the aircraft's maximum instantaneous and sustained turn rates as a function of airspeed (usually indicated, calibrated or Mach number) for a given altitude, power setting, weight, and configuration. This is the maneuverability part of the diagram. E-M diagrams also usually contain contours of constant specific excess power (Ps) across the airspeed range. This is the energy part of the diagram. Unfortunately, the AW manual only provides enough data to generate one sustained turn rate point (maximum sustained turn rate at sustained corner velocity) and doesn't provide enough data to generate any Ps contours. I hope to acquire the necessary data from Kesmai so I can add these later.

This method of aircraft performance comparison was developed in the 1960's. The F-15 Eagle was the first US fighter designed and developed using E-M diagrams, also know as "doghouse" plots due to their shape, as a primary design trade-off tool. Doghouse plots are today's fighter pilot's "bible". They tell him how his aircraft will perform in the within visual range (WVR) fight, and given an E-M plot of the threat, will show him where he wants to fight the enemy to maximize his strengths and minimize those of his adversary.

Ok, so what are these plots showing you. The blue line is the maximum instantaneous turn capability of the aircraft across its airspeed range for the given altitude and weight. Power setting really has no effect on this for these aircraft. The apex of the curve occurs at the slowest speed where you can generate the aircraft's limit normal load factor, ie G limit. This airspeed is the instantaneous corner velocity. The portion of the curve to the left of the apex defines the lift limit, ie the aircraft will stall (reach its lift limit) before it reaches its G limit. The curved portion of the curve to the right of the apex is the G limit. This defines the maximum normal load factor the aircraft is rated for at the given weight. The straight vertical portion of the blue line on the right hand side defines the maximum level flight speed. This is a cluge on my part, because that line should really be the maximum speed (ie do not exceed speed) for the given altitude. However, I didn't have that data so I just used maximum level flight speed instead, so sue me . The yellow X is the maximum sustained turn rate. This occurs at the sustained corner velocity. Ideally, we'd have a yellow curve like the blue curve to define how sustained turn performance varies with airspeed, but I don't have that data yet. You'll also notice a patchwork of light grey lines. These denote lines of constant G loadings and turn radii.

You'll probably notice that the A6M5a Zero is not included. That's because when I backed the data out it said it was doing 18g. Sorry, I think there's an error in the AW manual data . I knew it wasn't gonna work when I saw those 70+ deg/sec turn rates. :)

I haven't verified this data, I just applied the necessary equations to the data given in the AW manual to back this stuff out. The whole reason I did this was because I felt AW's flight model was close enough to the real thing that it was worthwhile. I know there are some problems with how they model the stall, so the left side of the doghouse may not always come out right, especially if you make very abrupt stick inputs. I also know the aircraft doesn't break at the G limits depicted. It's not supposed to, not in real life (tm) anyway, you a 1.5 safety margin in real life (tm). I do think this gives you a better idea of how the aircraft compare. I was sold on the validity when I saw the Ki-84 data. I knew I love that aircraft for a reason. It turns up its own butt just like the F-16 :).

Anyway, if anyone finds any major glaring errors or has suggestions, don't hesitate to contact me. I hope to get more data from Kesmai to do this up right, and also do some overlay comparisons later. 

Stuart Butts, #6333
 Mister Ed
FSFORUM Air Force
The Flying Squirrels
"Watch Yer Nuts"
September 1994
CIS:  71553,356
GEnie:  S.BUTTS2

EM Diagrams - Doghouse plots

Last modified: Mon Sep 19 20:39:51 CDT 1994
Jim Knutson (Red Beard), knutson@cactus.org