Navion N5375K modeling
These functions are based on several datapoints, induced and parasitic drag, the changing shape of the presented drag at high AOA and the prop efficiency w.r.t. AOA. No Guarantees implicit or otherwise
are implied, your mileage may vary. Don't sue me because you were stupid enough to use this! Don't have
your relatives sue me because you were stupid enough to use this, run out of fuel, hit a truck on the
runway, or in general do incompetent stuff! I take no responsibility for your actions, take some
responsibility for your own actions!
NOTE: This shows the relationship between IAS(in MPH) and engine hp (HP2, in horsepower percentage).
I now have a general solution for the reverse IAS(in MPH) in terms of engine HP (in percentage)
BTW there are 2 solutions for most IAS's in front of and behind, the power curve.
HP1 is fitted with excel to best match of a/IAS+b*IAS^3 (26.38761/IAS+1.33E-07*IAS^3)
HP1=(26.38761/IAS+1.33E-07*IAS^3)
HP2 is fitted with the cosine fudge factor which is apparently missing from a Bonanza I profiled.
HP2=-0.548/cos(1.964988*HP1+2.413564) hp #2 fits closer than the measurement uncertanty for my engines power.
Using Power percentage Induced = 26.38761/IAS and Power percentage Parasitic = 1.33e-07*IAS^3
and Drag Induced = 325*285hp*Power percentage Induced/(IAS*.868) and Drag Parasitic = 325*285*Power percentage Parasitic/(IAS*.868)
And using excel solver the interesting points of v speeds are
Vglide=Vmin.power=90.1MPHIAS at 2900lbs
Suprise suprise these numbers look good for the navion.
LA=26.38761:LB=1.33E-07:HP=percentage horsepower (i.e. .75 for 75% power in my case 285hp==100%)
RQRTC=(HP/LB)^4/16384-(LA/(12*LB))^3
IF RQRTC > 0 THEN RQRTC=SQR(RQRTC) ELSE PRINT "Not enough hp for straight and level flight"
BA=(((HP/LB)^2/128)+RQRTC)^(1/3)
BB=(((HP/LB)^2/128)-RQRTC)^(1/3)
RL=(BA+BB)^.5
MTH=(PI-ATN(SQR(3)*(BA-BB)/(BA+BB)))/2
MR=2*COS(MTH)*(.25*(BA+BB)^2+.75*(BA-BB)^2)^.25
ias=(RL+MR)
Derivation of the above ias=f(hp)
Why is the navion paying a high penalty for high AOA above and beyond the already calculated induced drag?
Of course the datapoints I have for the bonanza is above its Vl/d where some of my datapoints are below,
so I might not have the data I need for a high enough AOA to start affecting Bonanza's data. So I suspect
The cos() term used to bring the horsepower needed by total drag into line with the horsepower generated
by the engine is a combination of change in prop efficiency and change in 'barn door'(induced drag) due
to the navions changing foreward looking face at high AOA. i.e. A navion is not a flat plate. :-)