Sender: <marv@lancaironline.net> (Marvin Kaye)
To: lml
Date: Tue, 30 Jul 2002 16:40:06 -0400
Message-ID: <redirect-1660310@logan.com>
From: Jeffery Peterson <jbp@fire.phys.cmu.edu>
Subject: RE: turbine butterfly valve. 
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Rick Schrameck wrote:

>I do not get it. I am a turbine fan and thought long and hard about
>building a Legacy with one. But here is what stopped me. Price per HP and
>fuel burn.  A turbine is just like a normally aspirated engine, it looses
>power the higher it goes. Having said that why would you trade 300 HP of
>Cont or Lycon power for the same turbine power with much higher fuel
>burn.
>TBO is not a good enough answer. How many experimental planes have run out
>a cont. 550? It does sound cool.

Rick,

-Price of the ATP is $35K for 300 HP... comparable to turbo charged 300
   HP piston engine.
-Fuel economy is reasonable in their tests of the 200 HP version.
   I think their fuel injection system is helping here
-I thought the trubine were optimized for high altitude and
   developed full power at the flight levels.

My main worry is the low power fuel burn, which is a fuel exhaustion
safety issue.   But, I think the butterfly valve solves that.

Gary Casey wrote:

>The cruise fuel consumption might be 50% higher and the idling fuel
>consumption much, much higher than a piston engine. Even by adding
>another 200 pounds of fuel the endurance might be less than with the
>piston engine. It looks like they did a very nice job, though.

Gary:

They say the cruise fuel use is not 50% higher than with pistons.
Sorry, i dont remember the numbers they were quoting from thier
rv4 test plane.  perhaps 20% higher??  And I think the butterfly valve
solves the idle fuel use problem...fools the turbine into
thinking its at 20,000 feet.

also, remember that you save 100 lb on the engine, so the
first 100 lb of fuel comes at no weight penalty.

and it runs on #1 heating oil at $0.90/ gallon !

-Jeff