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-   -   I Don't Get It - FP vs CS (https://vansairforce.net/community/showthread.php?t=80855)

paul mosher 03-03-2012 03:37 PM

read a book
 
prop governor. look it up.

Moura 03-03-2012 03:41 PM

Quote:

Originally Posted by paul mosher (Post 635897)
prop governor. look it up.

Thank you Paul.

L.Adamson 03-03-2012 05:53 PM

Quote:

Originally Posted by Moura (Post 635896)
Another stupid question, if I want To slow down in circuit and move blue knob all the way forward, the engine's rpm will go up. Can it in any way damage the engine due to over reving? Same would apply in formation in a dive!

You don't have to move it all the way forward. It still acts like a brake. In fact, if you move it forward too soon, it is like quick shifting into lower gear. Throws you towards the panel, and doesn't do well for the engine either. Just push all the way in on short final, when power is pulled back. I'd just usually leave mine, at the 2350 cruise setting. You'll only notice that the blue knob isn't full forward, if you do a go-around or touch and go. You'll notice a definate decrease in power.

Moura 03-03-2012 10:14 PM

Thank you L. But I was wondering what would be a reasonable / aceptable RPM in such a situation. Max. Take off rpm? Or could we go higher?

PerfTech 03-03-2012 10:25 PM

Quote:

Originally Posted by Moura (Post 636018)
Thank you L. But I was wondering what would be a reasonable / aceptable RPM in such a situation. Max. Take off rpm? Or could we go higher?

The max is set by the prop manufacturer, most Hartzell or Whirlwind compact is 2700 rpm red line. Allan

paul mosher 03-03-2012 11:17 PM

gov
 
actually prop rpm is restricted by prop manufacturer. Exceed rpm limits and it is a mandatory overhaul.

NickAir 03-04-2012 02:59 AM

Max RPM
 
Also, Lycoming engine O-320/O-360 Max rpm is usually 2700, therefore many prop designs are same.

smokyray 03-06-2012 08:32 AM

Not so fast...
 
Quote:

Originally Posted by paul mosher (Post 636025)
actually prop rpm is restricted by prop manufacturer. Exceed rpm limits and it is a mandatory overhaul.

Not quite. 2700 Max RPM on C/S props is correct for most manufacturers recommendations for certified applications and has carried over on experimental props sold to be installed on Lycomings. Being an IA I'm sure you know once you paste "experimental" on your type certificate, all bets are off. You don't have mandatory limits on anything per say, except your conscience, your posterior and the approved limits/maneuvers posted in the logbook during the test phase. If you follow certified standards and limits for your RV experimental airplane's engine/prop, good on ya. Years of testing, NTSB investigations and lawsuits have set the ultra-conservative limits on most parts sold by major aircraft parts companies. They do however perform very well beyond posted limits...

Even Hartzell likes racing airplanes and their custom made props for Dave Anders, the Reno Lancair Legacies and others have higher RPM limits (2900-3200) and were built specifically to run at higher RPM's. How are they different form a stock Hartzell? Call Kevin Karam at Hartzell, he'll tell ya. Craig Catto's background is Reno racing. His props come into their own around 2850 and "posted limits" up to 3200 for my 2 blade. Lycoming's limits running above 2700? That's another discussion for another day. Ask Mahlon, he's on the site.

FYI...

V/R
Smokey

MauiLvrs 03-06-2012 10:43 AM

Quote:

Originally Posted by rockwoodrv9 (Post 634917)
Does the extra knob add that much workload for a low time pilot?

No....
Quote:

Originally Posted by rockwoodrv9 (Post 634917)
I plan to go with a fuel injected engine to reduce the leaning needs and chance of error and engine repairs.

I don't see how fuel injection would in any way reduce the leaning needs in a noticeable way :confused:

gasman 03-06-2012 05:26 PM

What is the maximum and minimum pitch of a c/s prop on a RV7 180hp?

Sensenich is fixed at 85 inches.


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