Redline (formerly the Beater thread)

Jay Honeck wrote:
However, how is it that you can up the RPM limit of a given engine simply
because you want to keep the prop tips subsonic?

You would decrease the RPM limit, not increase it, to keep the tips
subsonic.


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__!__
Jay and Teresa Masino ___(_)___
http://www2.ari.net/jmasino ! ! !
http://www.oceancityairport.com
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However, how is it that you can up the RPM limit of a given engine
simply
because you want to keep the prop tips subsonic?

You would decrease the RPM limit, not increase it, to keep the tips
subsonic.

Understood. If you lengthened the prop, you'd have to decrease the RPM
redline to keep the tips subsonic.

However, the part of the question I was referring to was if you *shortened*
the prop. Part of the original post implied that you would be able to
simply *increase* the engine's redline RPM if you shortened your prop,
regardless of engine limitations. I don't believe this is true.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

On Mon, 14 Jun 2004 19:39:46 GMT, "Jay Honeck"
wrote:

However, how is it that you can up the RPM limit of a given engine
simply
because you want to keep the prop tips subsonic?

You would decrease the RPM limit, not increase it, to keep the tips
subsonic.

Understood. If you lengthened the prop, you'd have to decrease the RPM
redline to keep the tips subsonic.

However, the part of the question I was referring to was if you *shortened*
the prop. Part of the original post implied that you would be able to
simply *increase* the engine's redline RPM if you shortened your prop,
regardless of engine limitations. I don't believe this is true.

It isn't true. Theoretically, you could increase the redline rpm
providing you don't exceed the limitations of any other part of the
"system", such as the engine. The redline would have to be based upon
the most restrictive component.
Rich Russell

Found the source, sort of...

http://www.airweb.faa.gov/Regulatory...rgAdvisoryCirc
ular.nsf/0/c2f903127f0f41e4862569ae006d44d7/$FILE/AC20-88A.pdf

ANNOUNCEMENT OF AVAILABILITY OF ADVISORY CIRCULAR 20-88A; LINES ON THE
MARKING OF AIRCRAFT POWERPLANT INSTRUMENTS (DISPLAYS)

g. Tachometer (Reciprocating Engine Aircraft)
Red Radial - At maximum permissible rotational speed (rpm).
Green Arc - From maximum rotational speed for continuous operation to
minimum recommended for continuous operation (except in the restricted
range, if any). For propeller driven small airplanes which must meet
the requirements in Appendix F to Part 36 of the FAR at maximum normal
operating power, from the corrected rotational speed used to establish
the aircraft noise level to the minimum recommended for continuous
operation (except in the restricted ranges, if any).
Yellow Arc - From maximum rotational speed for continuous operation to
maximum permissible rotational speed.
Yellow Arc (Offset) - Conditional operating range for one engine
inoperative flight that exists above the normal takeoff rating limit
(if applicable).
Red Arc - Range(s) in which operation is restricted, except to pass
through, for all operating conditions because of excessive stresses,
etc.

Jay Honeck wrote:
However, the part of the question I was referring to was if you *shortened*
the prop. Part of the original post implied that you would be able to
simply *increase* the engine's redline RPM if you shortened your prop,
regardless of engine limitations. I don't believe this is true.

I think at that point, you'd be getting into limitations of the engine
components (with some tolerance).



--
__!__
Jay and Teresa Masino ___(_)___
http://www2.ari.net/jmasino ! ! !
http://www.oceancityairport.com
http://www.oc-adolfos.com