Message-ID: <000e01c1a583$d5750780$6b30b43f@f3g6s4>
Reply-To: "Dan Schaefer" <dfs155@earthlink.net>
Reply-To: lancair.list@olsusa.com
From: "Dan Schaefer" <dfs155@earthlink.net>
To: "Lancair list" <lancair.list@olsusa.com>
Subject: Re: Constant speed prop
Date: Fri, 25 Jan 2002 01:36:56 -0800
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FWIW. Aircraft with the wide useable speed range of the Lancairs (all types)
can really use a CS prop, if for no other reason than take-off performance.

For the first couple hundred hours on my 235 (O-235-L2C with the Lyc high
compression pistons, giving about 120 - 125 HP at sea level), I ran a fixed
pitch wooden prop pitched for cruise. This prop was set up to give about
2650 RPM, WOT at 7500 to 9500 ft. which seemed to be the best setup for this
earlier LNC2. Typical cruise speed was right at 160 kts. Unfortunately, the
best take-off RPM achievable at sea level with this setup was a meager 2350
RPM, and since shaft horsepower is directly related to RPM, I gave up a lot
during the take-off. (There are a couple of "bite marks" on my seat
upholstery to attest to this). Typical of a slippery airplane like the
Lancair, once I got airborne and gingerly coaxed the airspeed up to about
130 (MPH), the RPM began to come up and the ROC always went up to around
1000 + FPM.

I then installed a MT electric CS prop which allowed the engine to produce
2650 - 2700 RPM at the start of the roll (engine red-line is 2800
continuous). Full gross weight take-offs became non-events, following the
installation. Fuel flow during take-off and climb out went up by nearly 50%
and the consensus is that I must be making quite a bit more power during
that phase of flight. Cruise speed, at approx. 2550 RPM, at the above
mentioned altitudes, went up by a few kts (fuel flow settled down to the
normal rate seen with the fixed prop) but even if airspeed had stayed the
same, the improved take-off performance is worth every penny!

Cheers,

Dan Schaefer
N235SP

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