There were those who claimed that there was no way that would work.  Well, I reduced my inlet area from 48 sq inch to 28 and it works just fine thank you.  Tracy Crook can vouch that I have flown with the small openings for well over a year and he has never seen steam or smoke coming from my engine - yet {:>).

Hey Ed...that was probably me!  All my analysis uses Military Air outside conditions (+40 deg F over standard conditions), are climbing at 100 mph TAS (near max rate of climb) and assumes that you are actually generating 200 HP.  At 2,000 ASL and +40 deg F over standard....I suspect you are not generating 200HP and if you are indeed capable of 200 HP probably do not maintain that operating condition sufficiently long (at 100 mph) to reach steady state conditions which my rules of thumb consider. 

 

Hopefully if you ever are approaching the trees on T/O under the more severe conditions you can tolerate 245+ deg F engine out coolant temperature.  Been there done that with the Mooney.  You know what?  The throttle stayed in WOT and no leaves on the belly!  It defined "pucker" for me.  So you'll have to forgive me if I size my inlets just a little bit larger for our 95 deg summer days.  (Military Air at sea level is 99 deg F)...WOT...generating 200 HP for an extended period!!  Do what Tracy "noodles" and spray water on the heat exchangers!!  Of course you have to carry that two gallons of water around for the inevitable situation :>).  Sort of like a "gear up...not if, but when...if one flys enough.

 

Incidentally we unavoidably reached those 245 deg F engine out temperatures while developing my friends system without "apparent" ill effects.  He does not have sufficient hours to determine if there were long term effects, but water and oil are still separate!  Being a little experienced with automotive tests I would estimate that short of rapid temperature "shock" at those temperatues, no damage was done.  Note:  one of the OEM Automotive tests of heads/head gaskets is to dump just above freezing water into the engine inlet side of the waterpump while running at full tilt!!  That is thermal stress!

 

SWAG (valuable engineering tool), I believe you have what is almost a reverse venturi duct and your "effective" inlet area is actually larger than 28 sq. in. which is probably your smallest area in the inlet duct.  I have "noodled" (another valuable engineering tool!) that what you are doing might very effectively compensate for a very short inlet duct....but probably is a small detriment to cooling drag.  Too small to matter IMO.

 

Hey, you are a terrific experimenter and an invaluable Hummmmmer flyer who is willing to share even at the risk of us "still building" asking questions trying to understand what is happening in the Big RW.  It is terrific you share so we can consider what you have done and if we are smart....will try to implement same in our own builds.

 

I truly appreciate your combination of theory, practical application and ability to write!!  Thanks!

 

Doug in CO