Skyhawk CS prop?

DavidWhite

DavidWhite

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I got to thinkin' "boy wouldnt it be nice when overhaul time came to install a CS prop?"

My first question is, does such an animal exist? I know the RGs have a CS prop but I was wondering about an STC for a regular 172
 
DavidWhite said:
I got to thinkin' "boy wouldnt it be nice when overhaul time came to install a CS prop?"

My first question is, does such an animal exist? I know the RGs have a CS prop but I was wondering about an STC for a regular 172
Click to expand...

I've seen 180 HP upgrades that included a CS prop, but I'm not sure which ones they are.

John
 
DavidWhite said:
I got to thinkin' "boy wouldnt it be nice when overhaul time came to install a CS prop?"

My first question is, does such an animal exist? I know the RGs have a CS prop but I was wondering about an STC for a regular 172
Click to expand...

You can find STCs on the FAA web pages. Need to make sure the STC is for your engine model.

Also check the Cessna Owners Group.
 
Most of the engines used in the 172's aren't set up to run a C/S prop due to differences in the crankshaft and cases. First thing is to check your model and see if its even possible. Check the wikipedia page on lycoming O-320's. There is a list of dash numbers and features. My 175 has an O-320 B3C which was an Apache engine and it uses a constant speed prop. The same engine setup was at one time STC'd for use in the 172 by one of the companies who also did the O-360 conversions with and without C/S props. The company was (is?) called RFB. You may be able to install a C/S prop or you might have to do an engine to do it. Frank
 
DavidWhite said:
I've got an O360A4M
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I think you're screwed. The A2A on up had no provisions for CS prop. You need one of the O-360-A1x series of engines. I'm pretty sure only the "1s" of the A series can mount a CS prop.
 
I don't think it makes sense on a fixed gear 172 or Cherokee 140. If you seriously upgraded the power then maybe, but then it's a 182 with no room inside.
 
If you want a CS prop, check into some of the MT Electric prop conversions. I believe the 172s have an STC for one, and it might even be a 3-bladed prop that looks cooler.

That said, I doubt you're going to see any significant benefit. The plane isn't fast enough, and the CS prop won't make it significantly faster.

That conversion Tom linked to is interesting enough, but a 172 with a 180 HP engine is plenty. The plane is designed for slow.
 
I'd be surprised if the CS prop didn't actually slow the plane down, actually. The machinery involved has quite a bit of weight, and I doubt you'd come out ahead, depending somewhat on what kind of flying you do. Maybe if all of your flights are long cross countries... maybe.

Still probably wouldn't be worth it as it would cut your useful load down by a couple hundred pounds and make merry hell with your weight and balance. Would also tax your engine mounts, especially since it'll probably run out of elevator authority and land with surprising conviction if you chop the power too early.

Trading up to a 182 might actually be cheaper. No idea what major engine modifications cost, but since it involves an airplane, I'm guessing it's a bundle.
 
thomascannon said:
I'd be surprised if the CS prop didn't actually slow the plane down, actually. The machinery involved has quite a bit of weight, and I doubt you'd come out ahead, depending somewhat on what kind of flying you do. Maybe if all of your flights are long cross countries... maybe.

Still probably wouldn't be worth it as it would cut your useful load down by a couple hundred pounds and make merry hell with your weight and balance. Would also tax your engine mounts, especially since it'll probably run out of elevator authority and land with surprising conviction if you chop the power too early.
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Weight would be one of the minor considerations. The fixed-pitch McCauley 1C160-DTM found on the 150-hp 172 weighs 35.5 pounds. The McCauley D2A34C67 found on the 210-hp 172RG weighs 47 pounds. The governor weighs maybe two or three pounds, the control cable another pound. We end up with a 14 or 15 pound penalty. Not a big deal.

Dan
 
The 172RG has a CS prop, the heavy gear to haul around, and slightly more horsepower than the 172, and is generally a total dog of an airplane.

There's a reason its nickname is "Gutless". ;)

The suggestion to go up to the 182 is sound. By the time you add enough horsepower to make a CS prop on a 172 really perform, you could'a been out flying a Skylane. ;)
 
Dan Thomas said:
Weight would be one of the minor considerations. The fixed-pitch McCauley 1C160-DTM found on the 150-hp 172 weighs 35.5 pounds. The McCauley D2A34C67 found on the 210-hp 172RG weighs 47 pounds. The governor weighs maybe two or three pounds, the control cable another pound. We end up with a 14 or 15 pound penalty. Not a big deal.

Dan
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Yeah, I suppose you have a good point. The weight of the CS prop is related to the overall size of the engine (and how much stress it's going to have to handle) and I was thinking of the difference in weight for larger engines than those.

It's a shame there are so few Cutlasses around these days. Both I had access to were pulled offline after the owners got tired of repairing the landing gear actuators or dealing with firewall issues from people landing the planes too hard (the gear is quite rigid). Nice little complex trainers and cheap to fly. Just not cheap to own, I guess. :nonod:

Never heard of any problems with the CS prop on those, so I guess it must work somehow!
 
We had a 172 in our club with a 180HP CS prop. It didn't go any faster, but it climbed much better than our other 172s on the line.

It was our go-to high altitude 172 until somebody decided to pass up fuel stops in a headwind. Ended up 60 feet short of the threshold of the destination runway.

--Carlos V.
 
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denverpilot said:
The 172RG has a CS prop, the heavy gear to haul around, and slightly more horsepower than the 172, and is generally a total dog of an airplane.

There's a reason its nickname is "Gutless". ;)

The suggestion to go up to the 182 is sound. By the time you add enough horsepower to make a CS prop on a 172 really perform, you could'a been out flying a Skylane. ;)
Click to expand...

Yes all those things exactly. Except I didn't notice the slightly extra power when I flew one.
 
denverpilot said:
It's used up carrying the gear and prop hub. LOL.
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True. The hydraulics, mechanisms, and extra structural stuff for wheel wells for the retracts will add a lot more weight than the CS prop.

There's a "homebuilt" Cessna not far from here. It has, IIRC, a 172 fuselage, 182 gear and tail, 206 wings and the 206's 310-hp engine. Now THAT performs. Too bad Cessna didn't have a little more fun in the engineering hangars when they were designing new models. Had to leave that until they bought someone else's design--Columbia Aircraft--and called the airplane the Corvalis.

Dan
 
DavidWhite said:
I got to thinkin' "boy wouldnt it be nice when overhaul time came to install a CS prop?"

My first question is, does such an animal exist? I know the RGs have a CS prop but I was wondering about an STC for a regular 172
Click to expand...

I used to own a Skyhawk with a 180 and constant speed prop. It'd cruise all day at 125kts and would out climb any 172 I've ever been in. It was a fun 172.
 
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