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- Ken Thompson
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- Posts: 136
19 Sep 2020 17:00 #1
by Ken Thompson
Replied by Ken Thompson on topic propellers
Andy I have the C85 Stroker STC and a 7148 prop. I do believe it’s the best possible compromise between climb and cruise. I fly out if 2480 foot strip at 300 MSL in hot, humid SE Texas. We have tall trees on one end of the runway and power lines on the other.
Even at max gross I’m easily airborne well before the halfway point getting better than 500 feet per minute.
And I cruise at 118 mph.
I don’t see the point of cruise props. You give up climb ability in exchange for three or four mph speed.
Maybe worth it if your base is a very long runway at sea level, in a cold, dry climate. And you often fly really long cross countries where getting there five minutes early is critical.
Even at max gross I’m easily airborne well before the halfway point getting better than 500 feet per minute.
And I cruise at 118 mph.
I don’t see the point of cruise props. You give up climb ability in exchange for three or four mph speed.
Maybe worth it if your base is a very long runway at sea level, in a cold, dry climate. And you often fly really long cross countries where getting there five minutes early is critical.
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- Larry Snyder
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- Posts: 709
09 Sep 2020 12:27 #2
by Larry Snyder
Replied by Larry Snyder on topic propellers
Stallings Aircraft Propeller, LLC
PH: 870-208-8882
On-Call MB: 870-208-5198
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Hours of Operation
Mon.-Fri: 8:00 a.m.-5:00 p.m.
After hours as needed.
Address
1715 North Falls Blvd.
Wynne, AR 72396
PH: 870-208-8882
On-Call MB: 870-208-5198
This email address is being protected from spambots. You need JavaScript enabled to view it.
Hours of Operation
Mon.-Fri: 8:00 a.m.-5:00 p.m.
After hours as needed.
Address
1715 North Falls Blvd.
Wynne, AR 72396
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- Andy Mintz Mintz
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09 Sep 2020 12:00 #3
by Andy Mintz Mintz
Replied by Andy Mintz Mintz on topic propellers
Larry: love fishing the white river for trout mountain home, when we lived in monroe la. Hope to go back again.
Can you send me contact info for the shop in Arkansas please. I am going to get all the information on the c85 engine and our prop. To see if it can be pitched to help with climb performance. Thxs andy
Can you send me contact info for the shop in Arkansas please. I am going to get all the information on the c85 engine and our prop. To see if it can be pitched to help with climb performance. Thxs andy
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- Larry Snyder
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09 Sep 2020 11:54 #4
by Larry Snyder
Replied by Larry Snyder on topic propellers
It all sounds good. You can certainly get a prop repitched/overhauled less expensively than buying a new one. We have a good prop shop in Arkansas, but I'm sure there must be one in your area. I can't remember what an overhaul/repitch costs, but it would be far less than the cost of a new prop. One caveat is that a prop can only be overhauled so many times. Do you have a logbook on that prop? Regardless, I'm sure a good propeller shop can advise you on how to handle it. Good luck.
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- Andy Mintz Mintz
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09 Sep 2020 11:49 #5
by Andy Mintz Mintz
Replied by Andy Mintz Mintz on topic propellers
Larry:
Thanks so much for your quick response.
1) we are getting static rpm of 2250. So i think engine is ok. It just had major overhaul 30 hrs ago
2) i am getting my mechanic to see what pitch is on the propeller— that should tell us a lot as you mentioned.
3) could not agree to you more that a cruise pitch
On c85 engine over 50 results in poor climb and poor decent cruise. We are seeing this on the ercoupe just purchased. And it was mentioned to me that it is a cruise prop. Confirming.
4) can prop be repitched if so or am i looking at buying new prop to match up with c85?
5) the airfield with 3700 length has 50 ft Tree obstacles probably another 800 feet each end.
With that, i think we will still be ok at gross but i do want climb prop anyway. Would you agree?
Thanks Larry. I really appreciate the technical assistance. The ercoupe is a wonderful airplane.
Thanks so much for your quick response.
1) we are getting static rpm of 2250. So i think engine is ok. It just had major overhaul 30 hrs ago
2) i am getting my mechanic to see what pitch is on the propeller— that should tell us a lot as you mentioned.
3) could not agree to you more that a cruise pitch
On c85 engine over 50 results in poor climb and poor decent cruise. We are seeing this on the ercoupe just purchased. And it was mentioned to me that it is a cruise prop. Confirming.
4) can prop be repitched if so or am i looking at buying new prop to match up with c85?
5) the airfield with 3700 length has 50 ft Tree obstacles probably another 800 feet each end.
With that, i think we will still be ok at gross but i do want climb prop anyway. Would you agree?
Thanks Larry. I really appreciate the technical assistance. The ercoupe is a wonderful airplane.
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- Larry Snyder
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09 Sep 2020 11:19 #6
by Larry Snyder
Replied by Larry Snyder on topic propellers
That's not a very good climb rate for a C-85 at a lower altitude. I'd first look at what the pitch is on your current prop. Do you know what it it is now? You have to treat the prop and engine together as a single unit, and you have to consider them together. If you have a very high pitched prop, say 53, that could explain your poor climb rate. But if it's a lower pitch, you probably need to look into the engine to make sure it's generating power. I personally agree that the best prop for climb and decent cruise on a C-85 is a 7148. If you are going to be flying out of short grass strips I'd go 7146. I honestly can't figure out why anyone would want to go over 50. Make sure your carb is properly jetted for a C-85. I'd have someone who understands carbs go over it completely. With a C-85 you should be getting a static RPM f 2100-2250 or something like that. If your engine is not falling in that range, you'll need to figure out what's going on. Good luck!
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