Fred,

 

I once did a haphazard test with exhaust thrust.  In that example, the result was any reduction in exhaust pipe exit area (to increase nozzle speed) resulted in power loss.  I guess that means I should’ve opened up the exhaust system.

 

Would it be possible to post a copy of the paper you speak of?  Or email a copy?  I really appreciate the read.  Perhaps two shrunk neurotics would have a chance of assimilation?  I’d love the study.

 

Larry

 

 

“There is a free lunch - or at least a cheap one.”

 

Right you are, Scotty!  I merely was pointing out that one has to pay for more horsepower, or work for drag reductions.

 

 

However…..

 

There may be another nearly free lunch.  Exhaust thrust. 

 

I have a WWII NACA tech paper discussing the theoretical and experimental work done to determine the potential thrust from the exhaust of aspirated piston engines.  The faster you go, the more effective it can be.  So after evaluating all the cooling drag reduction work I have done, I plan to work on this area next.

 

First I will have to wade through all the equations and data and attempt to understand and interpret it with my ever-shrinking neuronal capacity. That is a project for the latter half of the year. Trading more back pressure (and presumably some power loss) for thrust improvement (via exhaust nozzles) is an interesting trade-off.

 

It is not a simple one.

 

 

“Combining power gains with drag reductions [and perhaps some augmentation of exhaust thrust] results in significantly greater performance.”

 

Want to try some experiments?

 

J

 

Fred, AKA

Captain Tuna, Chicken of the Skies