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I want a C/S, but will likely end up with a FP for the cost savings both in initial purchase price and maintenance.
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By the way, who are the best wood propeller manufacturers in USA?
Thanks |
I'd think that...
.... when a carowner has tried automatic transmission, he'd never want to go back to manual gearshifts anymore...
That's the case for me at least... :D Get a ride in a -7 with a C/S prop: do some short field takeoff and landings, some acro and then decide.... |
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Again personal preference, I would rather have a manual transmission over automatic any day. But that right theres proves the point. It all what you want, if you want simple, you cant get much more simple than one lever for power, push forward go fast pull back slow down. -david |
C/S or F/P
The simplicity of a fixed pitch has benefits:
- no moving parts - no grease - no leaking Zerk's - no down time for rebuild - no high $$ for rebuild - no problem out performing spam cans w/ your F/P - Top end speeds are same as F/P - There are fixed pitch props that flex flatter at max rpm when airspeed is low, (for better climb performance.) This will never compete with a C/S although appears to be a great compromise. - Tri blade F/P is supposed to provide more thrust at lower airspeed although it may be slightly less efficient. - Tri blade creates higher prop clearance to ground. If a RV pilot wants more performance at take off and climb then you can still stay with a F/P by going with a tri blade and/or a higher pitch. This will limit the top end to a lower speed as a direct trade off for the higher performance on take off and climb. This is common with small power bush planes for reasons mentioned above. |
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Best, |
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Best FP prop
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C/S
Grease on windshield? High maintenance? I've used C/S props for years and never experienced either problem. Get what you want.
It'll be cheaper to buy a C/S than buying a F/P and changing your mind later. But get what you want. |
additional workload for CS?
I have flown almost always with a FP prop. I flew some in a 182 that had a CS, but I didn't operate the prop since I didn't have experience with one - the plane's owner did the prop adjustments. That was several years ago and I don't remember much about it. How much more complex is it for a low time pilot? If I remember correctly, LSA does not allow it for that reason. I plan to go with a fuel injected engine to reduce the leaning needs and chance of error and engine repairs. The cost is an issue too and my major flight profile is traveling to visit kids and grandkids. I like the idea of increased climb and the ability to slow down getting in and out of smaller airports, but the -9 with a 360 or a 320 will not have any performance problems for sure with either type of prop.
Does the extra knob add that much workload for a low time pilot? It may be a question that may not have an answer more than a standard transmission - vs - auto would have. I appreciate the expertise here - it is hard to find something that people don't know about on this forum! |
Prop
C/S use is not a big deal. Look at all the extra knobs and switches people add to their airplanes with the EFIS systems they install.
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C/S or F/P
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I've heard this ONE too many times!
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If that were "apples-to-apples", there would be many cars running around with a "one-gear" transmission. Only place I've seen this is on the drag-strip. There are MANY airplanes flying just fine with F/P props. When is the last time you saw a car on the road with a one-gear transmission? |
Does this count?
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aerocar
Yes it does. And it's neither a good car or a good airplane.
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DO YOUR RESEARCH GUYS!
This car did NOT drive on the road with a single speed transmission!
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No, but it drove on the road with a fixed-pitch prop. I thought these were one in the same.
It had a 3-speed on the floor for driving the wheels. That's just like having a constant speed prop. ;) |
Car Transmission analogy.
Mel is correct. The car trans analogy is flawed in showing a comparison between a F/P vs. C/S.
Fixed pitch: $ lower entry price; low maintenance; no mechanical rebuild needed; lighter weight; no loss in top speed. Constant speed prop does have the advantage of helping to move the CG forward for a more usable useful load, depending on mission. Also C/S has the advantages of a climb prop at slower airspeeds, therefore allowing shorter takeoffs and climb capability. |
Air is a Compressible Fluid
You guys are off in Never-Never Land.
There's LOTS of difference between turning a propeller (either CS or FP) in a compressible fluid and driving a tire on a paved road. (Different way of saying that Mel is right again.) Reminds me of a debate by a buddy who challenged a so-called expert on model airplane propellers after the "s-c e" wrote an article in the AMA (Academy of Model Aeronautics) magazine. Put your thinking caps on. :) |
Where I work, we're building a car with a single gear fixed transmission and no clutch.
The trick is to use an electric motor that produces 100% torque at 0 RPM:D:D |
I was just...
.... poking you guys... :D
(with my comment automatic vs manual transmission) As already mentioned, I bet this post is just to poke us... ;) |
HP=TxR
Since HP=Torque X RPM, I like to think of the blue and black knobs as 2 ways to add or subtract power, together or individually...
Darn handy and works every time it's tried... |
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Constant speed prop just gives you some extra versatility. Depends on the operator if that is worth the cost. To each their own.
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It's really simple.
Do you want great performance at a lower cost, or do you want maximum performance and are willing to pay the difference. Excellent results either way.
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Flying out of mountain airports the CS prop can be VERY useful.
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Stupid question
What setting will slow down an airplane with CD, blue knob all the way forward or all the way back?
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Blue knob pulled back results in coarse pitch and max glide. |
C/S control
C/S Prop control:
Forward: Flatens the pitch for take off, climb or slowing. Back/out: Increases the pitch for high speed cruise/extended glide. |
Another stupid question, if I want To slow down in circuit and move blue knob all the way forward, the engine's rpm will go up. Can it in any way damage the engine due to over reving? Same would apply in formation in a dive!
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read a book
prop governor. look it up.
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Thank you L. But I was wondering what would be a reasonable / aceptable RPM in such a situation. Max. Take off rpm? Or could we go higher?
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gov
actually prop rpm is restricted by prop manufacturer. Exceed rpm limits and it is a mandatory overhaul.
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Max RPM
Also, Lycoming engine O-320/O-360 Max rpm is usually 2700, therefore many prop designs are same.
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Not so fast...
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Even Hartzell likes racing airplanes and their custom made props for Dave Anders, the Reno Lancair Legacies and others have higher RPM limits (2900-3200) and were built specifically to run at higher RPM's. How are they different form a stock Hartzell? Call Kevin Karam at Hartzell, he'll tell ya. Craig Catto's background is Reno racing. His props come into their own around 2850 and "posted limits" up to 3200 for my 2 blade. Lycoming's limits running above 2700? That's another discussion for another day. Ask Mahlon, he's on the site. FYI... V/R Smokey |
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What is the maximum and minimum pitch of a c/s prop on a RV7 180hp?
Sensenich is fixed at 85 inches. |
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