REFLECTOR: Higher RPMS

[Brainard, Jerry]

Rene',

 Did you make you own NACA or modify the factory.  If you made your own,
did you use the NACA ratios?


- jerry

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Rene Dugas
Sent: Monday, November 20, 2006 1:26 PM
To: 'Velocity Aircraft Owners and Builders list'
Subject: Re: REFLECTOR: Higher RPMS

Thanks to all.  I have raced boats, motorcycles and cars for years but
always appreciate others experiences and view points.  I've blown up
engines in small applications at 16,000 rpms and had lawn mowers hopped
up and blow at 3000 rpms.  I wish to be conservative but by nature I am
a racer.  I will continue to research.  I do not intend to use the
higher setting except if desired for climb out and acceleration to
cruise at 23/23 or 24/24.  Cooling has never been a problem.  I have
NACA's about one inch larger than the factor is now recommending.  Oil
in cruise is 165 degrees and CHT at 380 with EGT's 1450.  Large piston
diameter makes for large mass effect that multiplies rapidly as RPM's
increase. 
Thanks,
Rene'

-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Chuck Harbert
Sent: Monday, November 20, 2006 11:15 AM
To: reflector at tvbf.org
Subject: REFLECTOR: Higher RPMS

> 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'

-------------------

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









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