First i used metric units. Iīm simply used to them (ca=cl, cw=cd)
.
I made a little mistake, and put up a new pic.I added some other planes, too, have a look at the picture again
And something really important: Every formula i used, you used and everyone here used is so simple that itīs usually not enough to describe the characteristic of a real ac. A guy of a chair for flight mechanics told me that the mistake that you have with those simple formulas are often bigger than the differences between the ac.
I calculated with a constant prop effectivity from 100-400mph. I did not take into consideration that your elevator reduce total lift, and that this changes when you go faster. Drag from control surfaces, interferences between wing and airframe... there are so many variables
ok now to your question. I simply said Lift=weight*earth_acceleration or L=m*g
air density near the ground (i did all my tests near f8, sometimes i have the impression people do flight tests from fields which are in 1000-5000ft) is 1,225kg/m^3, g=8,81m/s^2
i calculated v[m/s]=v[mph]*1,61/3,6
m*9,81=camax*1,225/2 * A * v_min^2
I didnīt had a look at departure, i tried to hold the plane in the air.
BTW, i have an excellent table for drag coefficients for the 190A8, A9, D9, D12, TA152-C1 , 152 E1, 152H1. According to this table the fw190A8 had a camax of 1,59, like the other ones except 152H with camax of 1,7.
The 190 had a NACA230 airfoil btw, same like the F4u (though different in itīs thickness etc.)
In Nacareport829 figure 14 and 15 are the camax values for the corsairs, in service condition ~1,25-1,3
i donīt know why our acc. charts are different because i donīt know your method. I only can see at your calculation that acc for 60m/s is higher than for 50m/s (??).
The problem is that you donīt know the effect of the control surfaces. In a slow flight you must pull a lot >> much "negativ lift". And you donīt know the exact K value for the calcultaion of the induced drag. From earlier glide test i calculated for myself some K values, but they are all very high compared to 1/pi*AR. Esspecially for small ac where you need theoretically bigger surfaces (neg. lift) to hold the plan stable, so maybe that makes the difference. The answer knows only HTC. But how i said, you can do many little calculation, in best case you come close to AH values. And i donīt think theyīre (mine included) good enough to demand some improvements.
For the drag calculation i used
cw=cw0+Kca^2
cw0 from maxspeed
K from the glide tests (unfortunality not possible anymore because of prop drag
)
ca like camax for every speed.
I donīt know exactly how to handle propeff. so i simple said:
Trust=0.8* Pmax(nominal)/v
Facc=Trust-Drag
acc=Facc/m
climb=acc*v/9,81
Thatīs it. If you want my excelsheet mail me
Corresponding climbrates would be for my calc:
niklas
