Today's Message Index:
----------------------
1. 07:05 PM - Re: What engine are you flying (Tracy Crook)
2. 09:08 PM - Re: What engine are you flying (Tedd McHenry)
Message 1
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| Subject: | Re: What engine are you flying |
--> Engines-List message posted by: "Tracy Crook" <lors01@msn.com>
----- Original Message -----
From: "Tedd McHenry" <tedd@vansairforce.org>
> --> Engines-List message posted by: Tedd McHenry <tedd@vansairforce.org>
>
> On Tue, 17 Jun 2003, Tracy Crook wrote:
>
> > But the only reason why the Sube is slowed down more (in terms of
percentage)
> > than the Lyc is that they are specifying a lower percentage of power for
> > cruise,
>
> Yes, the Eggenfellner engine is cruising at less than 75 percent power.
At
> 8,000 feet and 4200 RPM it's putting out about 110 HP, according to the
power
> chart, which is 67 percent of rated power. But the point is that if their
> torque curve were narrower they'd have to either run a higher RPM even to
get
> 67 percent power in cruise, giving a higher piston speed and thus more
wear, or
> they'd have to run the same piston speed and even less than 67 percent
power.
> That's why the torque curve matters when converting an auto engine for
airplane
> use.
>
> Naturally, all that assumes a CS prop. With a FP prop, the torque also
matters
> because a flatter torque curve will give you higher static RPM and
therefore
> better take-off performance.
>
> Tedd McHenry
> Surrey, BC
Guess we need to define what a flat torque curve means in the context of
aircraft engines. Getting a reasonably flat torque curve between 4200 and
5600 RPM is not a big technical problem, this is a very small range in
automotive terms (1 : 1.33 ratio). The discussion started with the
virtues of Honda's VTEC technology being touted as advantageous for aircraft
applications. My point was that VTEC is aimed at smoothing out the torque
band over a MUCH wider area than would ever be taken advantage of in
aircraft applications, something like 2000 to 8000 RPM, (1 : 4 ratio).
Very nice thing to have in a car, but not needed in an airplane.
Excellent discussion Tedd, you know your stuff!
Tracy Crook
Message 2
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| Subject: | Re: What engine are you flying |
--> Engines-List message posted by: Tedd McHenry <tedd@vansairforce.org>
On Wed, 18 Jun 2003, Tracy Crook wrote:
> My point was that VTEC is aimed at smoothing out the torque
> band over a MUCH wider area than would ever be taken advantage of in
> aircraft applications, something like 2000 to 8000 RPM, (1 : 4 ratio).
Good point, I agree.
I enjoyed the debate, too. Nice to discuss these things with someone who
doesn't begin with the assumption that anything but a Lycoming is unsuitable.
I flew Charlie Walker's Eggenfellner-powered Glastar and I was very impressed
with it. I've yet to have the pleasure of flying a rotary, but I hope to
before long. (I've driven them on the street, and they are a gas!)
Tedd
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