Re: Fuel Pump?

[Stewart MacLund <sundie@lunaticfringe.org>]

Uh.  The jet that you fly has no reciprocating parts in the engine... 
If we were talking, say, wankel rotary engines, we'd be talking about
RPseconds, not RPM...  <grin>

Someone a while back posted calculations for when your pistons rings
start "floating", letting combustion gases by them, into the crankcase. 
This would be bad.  Hence a redline.

The sheer momental force in a piston engine is just unbelieveable to
me.  Imagine.  A piston head wieghs about, what, 4oz lightest?  At
600RPM (coincidentally, idle speed for the VR6), the piston is changing
direction 10 times a second.  Just TRY to move your hand back and forth
10 times a second.  Perfectly.  Every time.  Now, at 6000RPM (close to
redline), it's 100 times a second.  

I know i'm telling you all things you already know, but whoa.  THINK
about it.  That 4oz (8 oz, whatever) changing direction that many times
a second.  Again, whoa.  It's amazing that our engines even hold
together.

Just another silly point:  Top fuel dragsters only crank out 6k or 7k
RPM.

Sundie...

JetFutr@aol.com wrote:
> 
> my gosh people...the jet that I fly cruises at about 30,000 RPM...and we are
> whining over the difference between 4200 and 7200 RPM?  No doubt that the more
> times you redline your engine, the more it will cut down on its useful life.
> 
> Kevin

-- 


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Stewart MacLund				Systems Integrator
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