I have a question about constant speed props with the O-360 AVCON conversion. Currently running a standard pitch (no numbers here at work) prop that is pitched slightly to favor cruise.
What kind of performance changes could I expect from converting to a 76" or 80" Hartzell CSP? I have been speaking with Dave Stoots in Fairbanks about the prospect of a changeover. He holds several STC's for different conversions. Wanted to hear from people here with first hand experience or knowledge.
Thanks,
Jaime
Performance changes with Constant Speed Prop
Moderators: GAHorn, Karl Towle, Bruce Fenstermacher
Re: Performance changes with Constant Speed Prop
This post is going to elicit some very subjective responses. The difference is going to be similar to observing the difference between accelerating away from a red light with a standard transmission stuck in 2nd gear.... and doing the same manuever with a properly operating automatic transmission. The CSP will make the fixed pitch prop seem like a very deficient prop.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
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jon s blocker
- Posts: 217
- Joined: Tue Apr 23, 2002 1:56 pm
Re: Performance changes with Constant Speed Prop
Jaime,
I have the 80" prop and STC from David Stoots on my '53B with a Delair Lyc 0-360 STC. My plane is heavy, (lots of mods) and no STOL kit. The top speed is increased but not a whole lot. The change is in the take-off power. Take off distance is shortened and the climb out is much better. Each plane will get its own benefits from the change over. The change is expensive, but we started with a basket case, sold the firewall forward parts and started from there. If you plan to fly from higher density altitudes and or carry alot of weight , a C/S prop on an 0-360 is going to put you ahead in the game. Dave Stoots is GREAT to work with , and will bend over backwards to help you get your set-up right. I had a very good experience dealing with him. As for solid numbers on the change over, as I said, each plane will be different. Keep it light. Keep it in proper trim. You can expect about 10mph incresase in speed. The difference in take off and climb out, is what will really shine. Jon
I have the 80" prop and STC from David Stoots on my '53B with a Delair Lyc 0-360 STC. My plane is heavy, (lots of mods) and no STOL kit. The top speed is increased but not a whole lot. The change is in the take-off power. Take off distance is shortened and the climb out is much better. Each plane will get its own benefits from the change over. The change is expensive, but we started with a basket case, sold the firewall forward parts and started from there. If you plan to fly from higher density altitudes and or carry alot of weight , a C/S prop on an 0-360 is going to put you ahead in the game. Dave Stoots is GREAT to work with , and will bend over backwards to help you get your set-up right. I had a very good experience dealing with him. As for solid numbers on the change over, as I said, each plane will be different. Keep it light. Keep it in proper trim. You can expect about 10mph incresase in speed. The difference in take off and climb out, is what will really shine. Jon
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Jr.CubBuilder
- Posts: 517
- Joined: Thu Aug 12, 2004 10:33 pm
Re: Performance changes with Constant Speed Prop
I had two different prop pitches on my C145 (76/48 and 76/51) the 48 came with the plane and I had it pitched to 51 after a while.
I now have the Lyc O360, and the 76" Hartzell. The constant speed gives a real nice performance increase on takeoff and climb-out is great. I think the increase in cruise of the O360 and CS prop over a stock motor with a fixed pitch cruise prop is minimal at best, but it allows a cruise at stock speed with minimal fuel burn. I think it's just a more efficient setup, at 120mph indicated with myself and some camping junk in the plane I usually see a fuel burn of about 8.5gph. On a cool day with smooth air I've had it up to 135mph but the fuel burn goes way up, the drag on the 170 airframe goes way up if you try to push it faster I think.
The downside of the constant speed is the complexity, I had the money to get all the parts new when it was time to buy a prop so went with the constant speed, but if the govenor takes a dump on me it's going to be an expensive fix. If Hartzell comes out with an AD on my prop hub that will be another chunk of change to deal with.
If you are going to do the change you might want to check out the MT props, they are quite a bit lighter than the Hartzell, the 76" Hartzell on my plane was 51lbs with everything as I remember, however the O360 block is 20lbs lighter than the C145 motor it replaced. The MT prop is supposed to weigh in at 36lbs I believe, and on paper it makes a little more thrust as well. I'm curious how it feels to fly behind.
I now have the Lyc O360, and the 76" Hartzell. The constant speed gives a real nice performance increase on takeoff and climb-out is great. I think the increase in cruise of the O360 and CS prop over a stock motor with a fixed pitch cruise prop is minimal at best, but it allows a cruise at stock speed with minimal fuel burn. I think it's just a more efficient setup, at 120mph indicated with myself and some camping junk in the plane I usually see a fuel burn of about 8.5gph. On a cool day with smooth air I've had it up to 135mph but the fuel burn goes way up, the drag on the 170 airframe goes way up if you try to push it faster I think.
The downside of the constant speed is the complexity, I had the money to get all the parts new when it was time to buy a prop so went with the constant speed, but if the govenor takes a dump on me it's going to be an expensive fix. If Hartzell comes out with an AD on my prop hub that will be another chunk of change to deal with.
If you are going to do the change you might want to check out the MT props, they are quite a bit lighter than the Hartzell, the 76" Hartzell on my plane was 51lbs with everything as I remember, however the O360 block is 20lbs lighter than the C145 motor it replaced. The MT prop is supposed to weigh in at 36lbs I believe, and on paper it makes a little more thrust as well. I'm curious how it feels to fly behind.
Re: Performance changes with Constant Speed Prop
Had a chance to see a MT prop up close awhile back. And after seeing the bits of wood and other plant material imbeded in the stainless part of the leading edge, decided it is too light duty for the places I often go. Can't help but mow some grass or occasional willow twig sometimes.
Re: Performance changes with Constant Speed Prop
I'm watching this one with great interest. Constant speed is the only way to go for a price. 180HP on takeoff vs 110HP with stock set up on o-300. I see 135 to 140MPH at 9500 feet burning 8GPH @ 2300RPM. Take offs by myself on grass with full fuel are under 500 feet at sea level. Pull it back to 19 squared at 2500 feet I see about 105MPH on less than 6GPH. : 
I have a 53B with the avcon conversion, O-360 with hartzell 76" CS. 20 pounds extra with the prop- way out front. Two adults in front - foreward CG. Burn off fuel- really foreward CG, I mean outside the limits. 60 pound sandbag in the back helps. As soon as I can sell a couple more condos I will be majoring the O-360 and the prop. What do I want to do with the prop? It needs to be overhauled, has the hub AD requiring edey current inspection every 100 hours ( $250 plus two hours round trip plus taking a day off ). What are the other options available?
Scott
I have a 53B with the avcon conversion, O-360 with hartzell 76" CS. 20 pounds extra with the prop- way out front. Two adults in front - foreward CG. Burn off fuel- really foreward CG, I mean outside the limits. 60 pound sandbag in the back helps. As soon as I can sell a couple more condos I will be majoring the O-360 and the prop. What do I want to do with the prop? It needs to be overhauled, has the hub AD requiring edey current inspection every 100 hours ( $250 plus two hours round trip plus taking a day off ). What are the other options available?
Scott
Re: Performance changes with Constant Speed Prop
At those prices it won't take you long to pay for a new hub ($2800) & be done with that AD for good. My guy only charges $75 bucks for the eddy current inspection.Of course everything is cheaper in Georgia. 
Do unto others............
Re: Performance changes with Constant Speed Prop
Thanks all. After re-reading I realize my question was rather vague. Of course I wasn't looking for any "hard-and-fast" numbers, as the variables are too great between aircraft.
I will say, if you have any questions talk to Dave Stoots in Fairbanks. What a knowledgeable resource willing to explain things. Thanks for the other PMs I received. I understand constant speed much better now!
Jaime
I will say, if you have any questions talk to Dave Stoots in Fairbanks. What a knowledgeable resource willing to explain things. Thanks for the other PMs I received. I understand constant speed much better now!
Jaime