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  #1  
Old 06-03-2011, 08:48 AM
Rick of Austin Rick of Austin is offline
 
Join Date: Apr 2005
Location: 07TS Georgetown, Tx
Posts: 115
Default Is 1910 Static enough? -9a w/ 72x72 Catto

Thats what I am seeing as soon as I add full power on the takeoff roll. Its a 160hp RV-9a, recently I went from a climb prop to this very beautiful 72x72 composite prop. I asked for a cruise prop and thats what I have. The cruise is very quiet, super smooth and efficient. It will max at 2675rpm at WOT @ about 3,500. But as you can imagine my takeoff performance is marginal.
My strip is 2,900 feet of grass slightly sloped against my normal takeoff direction.
I used to let it fly itself off then accelerate to maybe 100+ for cooling and to let it spin up to higher hp. Using that technique now makes for a very flat climb out, uncomfortably so, especially for the neighbors in the house off the departure end
Would it be better to rotate to the best climb speed (maybe 75) and hold it there for the first couple hundred feet then flatten out? It just doest feel right to do that with only about 2100 rpm though
Thanks Guys
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  #2  
Old 06-03-2011, 09:48 AM
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dedgemon dedgemon is offline
 
Join Date: Feb 2006
Posts: 359
Default Yuck

This strikes me as patently unsafe, not to mention not any fun at all.
Go get a constant speed prop and get it over with.
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  #3  
Old 06-03-2011, 12:31 PM
krw5927 krw5927 is offline
 
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Location: Wichita, KS
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Default

It sounds like your field situation (grass, uphill, needing to climb out steeply) and your desire for a cruise prop are incompatible. Without a c/s prop, you get climb or cruise - never both.
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  #4  
Old 06-03-2011, 01:24 PM
Rick of Austin Rick of Austin is offline
 
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Location: 07TS Georgetown, Tx
Posts: 115
Default At Best Climb angle?

Well I already know its not as safe as it could be but a 3000' field is not exactly short. A CS prop is out of the question for me.
What do you guys think is best, holding best angle for 500' or a very flat climbout at 110?
Thanks
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  #5  
Old 06-03-2011, 02:05 PM
elippse elippse is offline
 
Join Date: Dec 2006
Location: Arroyo Grande, CA
Posts: 938
Default

You need to have a prop that maxes at 2700 rpm at 8000' dalt, at least. your static ought to be about 2100-2200. Get another prop!
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  #6  
Old 06-03-2011, 02:11 PM
David-aviator David-aviator is offline
 
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Location: Chesterfield, Missouri
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Default

If you upgraded to an O360 180 hp, the prop would be just about right.
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  #7  
Old 06-03-2011, 02:15 PM
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Andrew M Andrew M is offline
 
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Location: Secluded Lake,Alaska (AK49)
Posts: 359
Default I vote

I vote pitch for 75. Either your energy is in speed or altitude, either one makes little differance. As long as you are making enough power at that airspeed to be comfortable. Will speeding it up a little give you a little better climb? Does the climb prop change best angle due to power available at that airspeed? Or is that purely a function of A.O.A.?
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  #8  
Old 06-03-2011, 02:22 PM
Rick of Austin Rick of Austin is offline
 
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Default Thanks Paul

Will do, an email is on the way to Craig

Quote:
Originally Posted by elippse View Post
You need to have a prop that maxes at 2700 rpm at 8000' dalt, at least. your static ought to be about 2100-2200. Get another prop!
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  #9  
Old 06-03-2011, 03:19 PM
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LifeofReiley LifeofReiley is offline
 
Join Date: Jan 2005
Location: Round Rock, TX
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Quote:
Originally Posted by Rick of Austin View Post
Will do, an email is on the way to Craig
Rick,

Let me fly the prop one time and see what I can get her to do... I've got a 70X72 now, it's giving 2250.
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Last edited by LifeofReiley : 06-03-2011 at 03:22 PM.
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  #10  
Old 06-03-2011, 03:27 PM
PropMan PropMan is offline
 
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Location: Donie,Texas
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Default

You should get 2200 static to be safe
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