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  #11  
Old 08-05-2010, 04:11 PM
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apkp777 apkp777 is offline
 
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I don't know how to throw this into the mix, but what about the ground adjustable prop from Sensenich. Where do you think this falls?
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  #12  
Old 08-05-2010, 04:18 PM
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Default FP vs CS

...and don't certain models of the Hartzell constant speed prop on certain lycomings have an RPM range to avoid at certain power settings? I don't think it's true for the blended airfoil props, but rather for some of the older Hartzell CS props. The details escape me now.
There's a lot to know in this area before one makes a good decision. Do lots of homework.
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  #13  
Old 08-05-2010, 04:23 PM
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Quote:
Originally Posted by Sam Buchanan View Post
The restricted range for the Sensenich FP prop on an O-320 is rpm in excess of 2600.....
Sam brings up a fair point and as usual, is absolutely correct. To give you an idea of what that means in the real world, consider this: My Sensenich prop is bolted to an O-320, thus the prop RPM limitation exists. Since the O-320 engine develops 155 H.P. at 2600 RPM, we seldom approach anything near max engine RPM so it follows we enjoy pampering our engines automatically.


As for real world performance, I've showed skeptics over and over again with flight demonstrations. Just give me a modest tailwind component to work with and GPS measured groundspeed easily flirts with and often generously exceeds 200MPH. That is what I call efficiency on a blue collar budget.
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  #14  
Old 08-05-2010, 04:50 PM
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180 HP or better engine

CS prop
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  #15  
Old 08-05-2010, 05:05 PM
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My 7A O-360 has a constant speed prop. I just got back from flying a friends RV with an O-360 an a fixed pitch prop (I was flying solo to do the 'acro' checklist items he wanted on phase I).

Yes, the constant speed is awesome. However, the fixed pitch is still a great plane. His plane climbed way better than any spam can I've flown. So if the cost and maintenance is a turn-off, you might want to avoid the tempation to spend extra money (especially if lots of mtn flying isn't in the cards).

As for slowing down, it isn't a big deal - it just requires a little bit of planning.
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  #16  
Old 08-05-2010, 05:08 PM
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Quote:
Originally Posted by RVbySDI View Post
... The differences that will be noticeable will be on the takeoff performance and braking performance (slowing the plane down to land) you will see. This will be where you will have to make your decision as to whether the extra expense and weight is worth it.
Very true on both counts.
With just me on a cool morning with 20 deg flaps the takeoff roll can't be much more the 150 feet.

No problem getting it slowed down either.

Now if the engine quits, that would be a different set of trade offs....
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  #17  
Old 08-05-2010, 06:05 PM
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Quote:
Originally Posted by apkp777 View Post
I don't know how to throw this into the mix, but what about the ground adjustable prop from Sensenich. Where do you think this falls?
I think it will just end up at the most compromised setting...........most of the time. It won't be a climb prop like a C/S, won't have the braking ability of a C/S, and you won't being pulling the rpms back in cruise for quieter flight, as is done with a C/S.

Pulling the spinner everytime to change prop settings, seems like a bit of hassle to me. I just see this prop as being a compromise depending on the conditions..............and not adjusted all that often.

L.Adamson --- RV6A/ Hartzell CS
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  #18  
Old 08-05-2010, 06:33 PM
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Default ground-adjustable prop

For a person looking for a fixed pitch prop, I think the ground-adj prop has some advantages. You would be able to dial it in for best performance for your RV and you could decide what "best performance" is for you. Maybe if you are doing a lot of local flying, you might set it up for higher climb rate and if you were doing a long trip or two, you could set it up for best cruise at a certain altitude. Certainly not as simple as a C/S, but if you werent going to buy a C/S anyway, that might be the way to go.
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  #19  
Old 08-05-2010, 07:17 PM
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Quote:
Originally Posted by L.Adamson View Post
I think it will just end up at the most compromised setting...........most of the time. It won't be a climb prop like a C/S, won't have the braking ability of a C/S, and you won't being pulling the rpms back in cruise for quieter flight, as is done with a C/S.

Pulling the spinner everytime to change prop settings, seems like a bit of hassle to me. I just see this prop as being a compromise depending on the conditions..............and not adjusted all that often.

L.Adamson --- RV6A/ Hartzell CS
That's what I am thinking. I see myself just having a more expensive fixed pitch prop that once in a while I tweak for a particular flight or two.
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  #20  
Old 08-05-2010, 07:29 PM
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N941WR N941WR is offline
 
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The question is, what is acceptable climb rates?

With my old fixed pitch prop on an 135 hp O-290, I could climb at 1800 FPM on a hot day, solo. Load up the plane at gross and it would "only" climb at around 1000 FPM. Oh bummer!

Granted, the CS prop will push you into the back of the seat when you push the black knob forward.

For me, it has been about useful load, fast cruise, and acceptable climb. Thus a FP Catto prop is my choice.

Notice how this is written, "I", "for me", "my choice". Your requirements may be different; however, no FP O-320 powered RV is a dog in climb or cruise, except when compared to another RV with a CS prop.
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