Re: REFLECTOR: XL engine choice: 260HP vs 300HP

[Alan Shaw <wingco@iu.net>]

Matt Harrop wrote:

>  decision is between the 260HP and the 300HP IO-540.

At 10,000' the HP difference is very little but the weight difference is still 50
lbs.   This weight can create as much drag as the extra horses can make up for in
speed.  Speed does not increase directly with power but speed does decrease to the
cube of the drag coefficient.  Going to the 300 hp lyc. appears to be past the
point of diminishing returns in this respect.  It also has tighter cooling fins
which make it more difficult and more drag to cool.

The only other alternative I see now is a small turbine they make in the Ukraine.
It is basically a copy of the Allison 420 hp.  It weighs about 200 lbs with gear
box and are prices similar to the Lyc. 540.  I'm doing research on them now.   I
think they don't have a trust bearing for a pusher.
Big problem.   The other problem is fuel volume, short endurance and fuel weight
(20+gal/hour at 7lbs./gal).

It will run on fuel oil or Jet A so fuel cost near home base can be less than a
C-150.  The other plus's are that it is light, reliable, low in maintenance,
powerful and has safer fuel.  Prop efficiency will also be better with the mini
cowling.

The battery goes on the back side of the fire wall for balance & better starting
power.  Turbine mechanics tell me if you put the fuel to it before you have
sufficient rev's you just bought a new hot section which cost about what the power
plant is worth.

Just thought I'd try and make your choices more interesting.

Alan