Here is my favorite plot of aircraft performance as
a function of various changes from Crawford's book.

Note that increased prop diameter does nothing for top speed.
Conversely a decreased prop diameter would not hurt top speed much.

An increased prop diameter really helps the climb however.

About a 10% increase is HP is roughly the equivalent of a 10% reduction
in drag as far as top speed is concerned. A 20% increase in HP
increased the top speed about 12 MPH in a stright line.
Little else hurts or helps the top speed in a straight line. Top speed
in a 2G turn is another matter entirely. Not covered in this book.

Paul Lamar

Paul - I have a BASIC program that predicts performance pretty well
and it computes induced drag, uses prop diameter, airfoil tables
wing span,shape etc. The 2G is easily modeled by increasing
gross weight by twice. Weight is a minor player in top speed,
and the turns in the F1 class course are a larger factor than on
the unlimited course. It took F1 guys a long time to get the message
on aspect ratio. Acceleration is also a factor in F1, but not so much
in unlimited with the paced start.
If you like I could run some straw man cases for you. Vance

Figure 4000 HP and a R3350 Rare Bear or Corsair R4360 size airplane and see 
what you get. The unlimited guys are saying pretty much 2.5 G's continuos 
at 500 MPH. If you are not going 500 you might not be pulling 2.5.
I think you will have to model the course.

Paul Lamar
 
The AirCraft Rotary Engine NewsLetter.  Powered by Linux.
ACRE NL web site. http://home.earthlink.net/~rotaryeng/            
Copyright 1998-2003 All world wide rights reserved.