In article ,
"John Carrier" writes:
Just out of curiosity, what is the source for all your PsubS data?

In the case of the numbers I posted, the inital data comes from teh
Standard Aircraft Characteristics for the particular aircraft. Using
the characteristcs of teh engine, I generate the thrust curve for that
altitude & speed range, which gives me the total for Drag. (For the
engine, I can dope it out with Sea Level Static Thrust & SFC data, the
bypass ratio, and overall pressure ratio.) Then come the fun part,
breaking the drag numbers down to the individual contributions, and
fit them into a predicticed curve for total drag coefficient.
Then I test vs. certain point conditions - Vmax at Sea Level, and
various altitudes for Vmax values, and PsubSmax at Sea Level, (Rate of
Climb), and the altitude at which PsubSmax = 100 ft/minute (Service
ceiling). If the numbers are within reason, then it gets plugged into
teh flight model section of the Mighty Wurlitzer to deliver a PsubS
matrix for all acheivable speeds and altitudes. (Much repetitive
work, let teh computer do it!) While that's crunching away, I'm
running mathematicl models of teh airplane geomety through LDstab and
VLM to get the stability derivitives and the control moments.
So far, I've got things tuned to deliver numbers with a nominal 3%
accuracy to the flight test data, which is less than the variation
that you'll find in a squadron-sized group of airplanes.

A-4F always clean. TA-4J on occasion clean.

Thanks, John. I don't have any good Skyhawk numbers yet, but it seems
that on a little jet like that, the tanks would make a big difference,
wrt drag.

--
Pete Stickney
A strong conviction that something must be done is the parent of many
bad measures. -- Daniel Webster