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  #11  
Old 02-04-2009, 05:59 AM
lancef53 lancef53 is offline
 
Join Date: May 2007
Location: Portland, ND
Posts: 424
Talking

I am going with CS, just because I want to.

I think your next question should be nose wheel vs. tailwheel, you can really get people fired up with that one
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  #12  
Old 02-04-2009, 06:01 AM
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Rick6a Rick6a is offline
 
Join Date: Jan 2005
Location: Lake St. Louis, MO.
Posts: 2,346
Default

Quote:
It's true that a fixed pitch prop. is lighter than a constant speed but not by as much as you might expect. It is a big solid hunk of aluminum and it uses a steel prop extension and six long 1/2 bolts (assuming an O-360). I don't know the exact amount but I believe it is inside of 10 pounds. The other factors are no prop. gov., control cable, or gov. drive (if it has been removed). I think the weight difference between a fixed pitch and constant speed is no more than about 15 lbs total. Scott McDaniels
I believe Scott, quoted here from a post of a few months ago is entirely reasonable in his ballpark guesstimate. My constant speed equipped RV-8 came in within a mere few pounds empty weight of my fixed pitch Sensenich equipped RV-6A. This is a real world comparison, not a guess.
Quote:
Originally Posted by L.Adamson View Post
I like being able to enter a pattern area without having to slow down miles ahead of time. You can just use the C/S to fit the circumstance.
This oft cited and common assumption is simply misleading and inaccurate. I can easily enter the traffic pattern environment at top speed in my Sensenich equipped -6A and without flying a wide pattern STILL slow down to Vfe in plenty of time to make a normal landing. My experience is far from unique. Whether you are looking through the backside of a constant speed or fixed pitch propeller...it is always important to know thy airplane.

Once we "makes our brags" it is quite natural to defend our personal choice with oft cited bromides that tend to support our decisions. I feel no particular need to defend one choice as superior to another. My advice is dispassionate and straightforward. Equip your RV for the mission you will fly. For economical operating costs and perhaps a slight top speed edge, go fixed. If you fly out of short field/high altitude environments, or you simply want to experience kick-butt takeoff acceleration, go constant speed. How simple is that?
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  #13  
Old 02-04-2009, 06:37 AM
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L.Adamson L.Adamson is offline
 
Join Date: Apr 2005
Location: KSLC
Posts: 4,021
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Quote:
My quote:

like being able to enter a pattern area without having to slow down miles ahead of time. You can just use the C/S to fit the circumstance. Besides, constant speeds are quieter in cruise, and offer improved takeoff performace at higher altitude airports. However, most RV's can takeoff rather well with F/P's too! But, FWIW, I'd never give my C/S up.
Quote:
[/i] This oft cited and common assumption is simply misleading and inaccurate. I can easily enter the traffic pattern environment at top speed in my Sensenich equipped -6A and without flying a wide pattern STILL slow down to Vfe in plenty of time to make a normal landing. My experience is far from unique. Whether you are looking through the backside of a constant speed or fixed pitch propeller...it is always important to know thy airplane.[/i]
What's a polite way of saying............."Oh Bull"..

I've been around to many fixed pitched RV's, and well know the differences.
To say I'm being mis-leading is actually the inaccurate statement. No offense to those who figure they need to justify F/P.

L.Adamson --- RV6A Hartzell C/S
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  #14  
Old 02-04-2009, 06:53 AM
N208ET N208ET is offline
 
Join Date: May 2007
Location: St. Helens OR
Posts: 429
Default build what you want

I went with fixed pitch for economical reasons, but if I would have had the funding for a constant speed, I probably would have went that way FWIW.

Randy
8A Finishing, FWF
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  #15  
Old 02-04-2009, 06:56 AM
Adam Adam is offline
 
Join Date: Jan 2005
Posts: 269
Default Please!

I had a RV-4 for 15 years with a solid prop, constant speed is the way to go. Faster climb, quit cruse, slows down faster and no constant fiddling with the power. If your on a budget than one has to do what one has to do, but trying to justify the cost and fingering what it costs per hour, is insane! Figure what it costs to live in your house per hour x 24x365 x30 years,, makes a prop seem cheep!
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  #16  
Old 02-04-2009, 07:32 AM
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mikegraycmg mikegraycmg is offline
 
Join Date: Feb 2006
Location: Grand Prairie, Texas
Posts: 232
Default Fixed pitch

With some misgivings, I am going with a Catto 3-blade fixed pitch prop for reasons of cost. The good thing is that it appears to be considerably lighter than constant speed. How much, I don't know, but when I get the prop, extension and hardware, I'll let you all know the total weight for comparison purposes. Craig Catto also tells me that the pitch I'm getting should give me as high or higher a cruise speed than a constant speed prop. I'll also let everyone know my performance figures whenever I get them.

I very much wanted a constant speed prop, but I have been flying a friend's RV4 with a Sensenich, and the performance is so good, even with 150 hp, that I just can't justify the expense of a constant speed propeller. I have to be more ahead of the airplane to slow down properly than with a constant speed, but it just requires a little extra planning. if I had all the money in the world, I'd be getting constant speed, but then if I had all the money in the world I'd be getting a Columbia 400 or a Lancair.
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  #17  
Old 02-04-2009, 08:20 AM
Steve Brown Steve Brown is offline
 
Join Date: Oct 2007
Location: Alviso, CA
Posts: 405
Default Since when is flying about slowing down?

Its true my Catto requires closer attention to speed management in the pattern. On the other hand, glide ratio is much better than with a CS prop. So, if glide ratio is included in the performance equation, it is not at all clear that CS has better performance.

I can plan my pattern work based on what my airplane does. However, I do not get to decide when or if my engine quits. I would say the FP is safer in an engine out emergency.

Last Saturday I flew my granddaughter into CVH for lunch. I easily made the first turn which is at 1000' from the start of rwy 31 pavement. On takeoff I was airborne before the same point.

Neither the landing nor takeoff were near maximum performance.

Operating out of APA & BJC (Denver area) on very hot days, I never got the "I wonder if I'm going to get off the ground" feeling during takeoff. By comparison, my last airplane, an M20J, was not happy at all taking off in thin air, even with its CS prop.

I've definitely fallen out of love with CS props. My view now is that if an airplane has plenty of horsepower for the job, FP is fine. For me, that includes all the RVs.
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  #18  
Old 02-04-2009, 08:29 AM
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JonJay JonJay is offline
 
Join Date: Jan 2007
Location: Battleground
Posts: 4,348
Default Not sure it matters?

Quote:
Originally Posted by panhandler1956 View Post
I plan to do a lot of formation, so a C/S is a must for me.
Although I do have C/S, I fly formation with fixed pitched folks, and they have no problems. As you know, it takes constant adjustments of power to hold position. Power changes on manifold pressure (C/S) or RPM(fixed) but the power is what it is in both cases. Slowing down after the break works the same, pull 2g's and power, fixed or C/S, you should still have chewed up your airspeed quickly and slowed to your target speed (100mph) and your C/S just became a fixed pitch. I cant think of any other examples that would be of concern.
Take this for what it is as I have never flown a fixed pitch in formation although I am sure there are plenty on this site who have done both and could offer more insight to this than I.
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  #19  
Old 02-04-2009, 09:16 AM
lsu-rv lsu-rv is offline
 
Join Date: Jan 2005
Location: austin tx
Posts: 109
Default fuel burn

ok, i'm leaning CS, but this thread is interesting. I plan on IO so i can run lean of peak easier. If i cruise 6K - 11K will a CS allow me to burn less fuel?

I have never flown behind fixed pitch in something faster than a 172 or citabria. My rv6a had io320 and CS and my bonanza is CS.

I don't want to start an argument, just some of you who have flow both please enlighten me on fuel burn at same speed and LOP with each?
jeff h
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  #20  
Old 02-04-2009, 10:40 AM
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Andy Hill Andy Hill is offline
 
Join Date: Dec 2005
Posts: 976
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We have a C/S... and run a Formation School with FP and C/S.

One aspect that has not been mentioned above is aerobatics... I'm doing some Formation Aerobatics and potentially Display stuff, and the carefree handling in these areas of the C/S, particularly approaching VNE, is a bonus

I do not think it is easy to justify a C/S if you on a tight cost or weight budget. By going FP, you will save a lot of $ (? ) and lbs... and the benefits of C/S are really subjective (see above posts), but not performance limiting.

Formation is not a problem, even mixing FP and C/S apart from Formation Takeoffs (C/S can follow FP but be aware the engine will be way back on power! - FP following C/S is not really practical) and tailchasing (not ideal, especially a the teaching stage).

Andy & Ellie Hill
RV-8 G-HILZ
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