Bill Freeman wrote:

 Tracy is burning 8.25 GPH at a cruise of 202 mph.

  8.25 gph x 6 = 49.5 lb/hr   since I don't know the
  BSFC, I'll estimate.

   for 0.65 lb/hp-hr  >>  it comes out to 76 HP
   for 0.60               >>    82.5 HP
        0.55               >>    90 HP
        0.50               >>    99 HP
        0.45               >>    110 HP

I don't think it is reasonable to expect better than
0.45 BSFC.   My guess would be about 0.55
+/- 0.05, or from 82.5 to 99 HP.   Probably
90 hp.   For a Lyc 150 hp motor, 75% is
112.5 HP, 65% is 97.5 HP, 60% is 90 HP.

Seems like a pretty reasonable overlap of
HP values, assuming a 150 HP RV-4 can cruise at
202 mph at 60-65% hp, and probably ( I estimate)
cruise at 210mph on 75%.  Is this somewhere
near correct ?

How does this square with the fuel burn of Lyc
powered RV-4s at that speed?  How big of an
engine is normally used in the RV-4 ?? (aren't they
O-320s, typically??? - or are they O-360s ??)

I'll bet the vibration is a lot lower at cruise than any 4 cyl
Lyc ever even *dreamed* about.

Bill

Being the worlds most experienced rotary powered airplane passenger 
you got that right! :-)

Paul Lamar
 
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