REFLECTOR: Higher RPMS

[Chuck Harbert]

> Question:  The AeroComposite has a rpm limit of 3000 and an overspeed
> limit of about 4000.  I was thinking of increasing my engine rpms up
> from the 2700 of the MT to 2800 or even 3000.  That is still very low
> rpms and should get better climb out on take off.  Thoughts?
>
> Rene'

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Rene, you can physically can run at higher rpms right now, and I know that 
people who race, do just that (heard up to 3,300 rpms), but I believe that 
most install the higher rpm engine components. I have a HIO-360 Lycoming 
(helicopter) that is rated at 2,900 rpm in my V which I found out has 
different connecting rods and lighter and stronger valve train to handle the 
higher rpms.

I've talked to Lycoming (570-323-6181) and Bart at Aerosport (250-376-2955) 
regarding higher rpm operations. The engine makes more horsepower as rpms 
increase (to a point) so you will be burning more fuel and have higher 
temps, particularly CHT's which may be a problem. Engine life is directly 
affected by operating at higher temps, especially >425F, even if you are 
allowed up to 475-500F (for short duration).

The higher you fly directly affects the loading on the engine because of 
less air pressure (unless turbcharged) creating lower hp and less of a load. 
Thus, you can run at higher rpms at higher altitude and still be under 
normally rated hp, but cooling is usually the limiting factor.

Your new Aerocomposite prop sounds like a winner. I've seen their blades and 
they are beautiful. Is it hydraulic or electrically controlled?  If you 
don't mind telling us, how much did it set you back? Thanks.

Chuck H