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

Since speed goes as the cube root of power, that 15% in hp will get you
about 4-5% more speed; maybe 9 or 10 kts; with about 15% higher fuel burn.
Of course even cruise speed there there is a small penalty for the
additional weight, but maybe only a knot or 2.

Biggest difference would probably be on takeoff roll; next biggest
difference on climb rate.

But these are my guesstimates.  I'm not an aerodynamisist (probably can't
even pronounce it).

Al Gietzen

-----Original Message-----
From: Matt Harrop <matt@mattcave.ca>
To: reflector@awpi.com <reflector@awpi.com>
Date: Saturday, March 13, 1999 1:26 PM
Subject: REFLECTOR: XL engine choice: 260HP vs 300HP

>I'm looking for opinions and experience with regards to engine selection
for my
>XL-FG project.
>I'm definitely going to stick with a certified aircraft engine, since I
>simply don't have the knowledge to feel confident with an auto conversion.
>So the decision is between the 260HP and the 300HP IO-540.
>My thoughts are that the 15% difference in horsepower isn't going to make
>much difference in performance.  I would think that the rate of climb would
>be the most improved.  15% isn't going to do much for the cruise speed.
>I'm leaning towards the 260, since I think the added weight and fuel burn
>are to big a trade off for the incremental performance improvement of the
>bigger engine.
>Can anyone help me out with this decision?