Re: Lycoming engine fails! Pilot survives!

Roger

Merlin (in P-51) turned 3000 rpm on take off. Prop speed was 1500 rpm
(2 to 1 reduction gearing).

Engine life was about 250+/- hrs (not in combat). 

Probably happened but never heard of the reduction gearing 'going
west'. Was not a 'common' failure mode to be worrried about.

Big John


On Wed, 03 Dec 2003 02:05:35 GMT, Roger Halstead
<[EMAIL PROTECTED]> wrote:

>On Tue, 02 Dec 2003 12:57:49 GMT,
>[EMAIL PROTECTED] (Corky Scott) wrote:
>
>>On Mon, 01 Dec 2003 17:20:55 GMT,
>>[EMAIL PROTECTED] (Corky Scott) wrote:
>>
>>  The PSRU was the one thing he felt should be done
>>>by people who knew how to do them, and contracted NIS to develop one.
>>>
>>>To make a long story short, the PSRU did not work well and things have
>>>been in litigation for a while.  Making a PSRU to handle 120 to 180
>>>horsepower is one thing, making one to handle over 400 horsepower is
>>>something entirely different.
>>>
>>>Corky Scott
>>
>
>Thanks Corky,
>
>I appreciate the info.
>As I see it (and I don't  know squat about PSRUs except their goal) a
>high ratio PSRU as used in a turbo prop which has a very high ratio
>(planetary) is easier to build than say the 2:1 or 3:1, BUT the
>planetary also has the advantage in being used on an engine without
>pulses being inherent in their operation.
>
>The life of a PSRU on a piston engine has to be complicated.  It not
>only has to handle linear torque and thrust, but virtually any other
>imaginable angle as well. Then it has to be designed to avoid any
>resonances with those power train pulses AND take the positive and
>negative torque without beating the snot out of the gears which means
>next to nothing for slack (which brings its own set of problems).
>Helical, double helical, spur, planatery...each with it's own set of
>pluses and minuses.
>
>BUT, didn't  the big 12 and 16 cylinder Vs in WWII have PSRUs? Course
>those engines had very short TBOs too.  Then again they weren't
>exactly babied either.

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