Thanks again guys I will look for Whees response.

I had that Hartzel on my M5 0-540 turbo.
Switched to an 86” Mac.
Mind blowing difference.
Different engines of course, but I love the Mac.

If composite is out of the cards, and cub like performance is the end game you might consider a pawnee prop pitched to +/- 42
1P235/AFA8442 . Good cub prop, if you're not certified. I know where a new one exists, that could be bought right, but am not sure of the pitch.

IMO it would be a shame to go fixed, but the owner of that prop is running fixed on his TIO-360 (Lyc) Dakota cub, so not much difference I guess...
Different strokes...

And FWIW, I've owned multiple MT's.... each was significantly more $$$ than the WW200A I had stashed for my never ending my exp cub project. Perhaps Covid shortages have changed things?


Take care, Rob

While it may not be the way you'd go I'll take this discussion in a slightly different direction. I'm in the final stages of my 170 engine upgrade, an 0-360A1D that was previously spinning a CS prop but now it will be FP. Before everyone screams at me about cruise speed hear me out and then flame away. For the fun flying I do; floats, wheel-skis TO performance was my sole concern not forward speed, glassy water and overrun water under snow. I looked very seriously at the Whirlwind ground adjustable prop (at A1 suggestion), it's a work of art and very appealing. However in the end I just don't see myself "adjusting" the blade angles very often. Therefore I decided to forgo cruise speed in favor of TO performance. I selected a suitable blade length pitch angle that should ensure rated rpm at TO power, less load on the engine, lightweight for the same reason, for C of G location and overall airframe weight.

Burners on, flame away

First off, I sincerely hope that the OP keeps us posted on his progress in building the subject airplane. The “Producer-type” conversions/ EX builds always have made a lot of sense to me, and, with that engine and the right prop, it should be a BLASTER.

That said, I’m like Rob….if there’s any way to use a constant speed prop, I’d try to go there. I have a lot of experience with MT props, and love them. I have an Ultra on my current ride and would do that again.

I can’t let Maple’s invite to flame get past me, but not really a flame….:

The advantages of a CS prop are far more than just increased cruise speed. In fact, I’d choose a CS prop MORE for the type of flying that Maple proposes, than for a cross country bird. Here’s why:

All you have to do is look at the “static rpm” limits for a fixed pitch prop to understand. As an example, an O-360 might be limited to a red line of 2700, but with a fixed pitch prop, the STATIC rpm limit will be quite a bit lower….in some cases say 2400 to 2550….or? But, your prop will NEVER (legally) turn 2700 on takeoff, or stuck in nasty snow on skis.

Now, hang a CS prop on that engine, and it will turn 2700 on every takeoff, assuming it’s set up properly. And, guess what rpm that engine actually develops its “rated” horsepower at? You got it: 2700 rpm.

So, by using a fixed pitch prop, you’ll never be able to use ALL the power that engine is capable of.

And, here’s an example of another advantage, applicable to skis:

You just got big time stuck on skis. Deep snow, overflow, whatever. You need every bit of thrust that engine can provide.

Fixed pitch, you open the throttle and hope for the best at 2500 rpm. Nope, not good enough.

With a CS prop, you push up max power, 2700. Still not quite there? Grab that prop lever, pull it all the way to coarse pitch, immediately followed by back to fine. That will create a surge of thrust you won’t believe…often just long enough to drag you out of that hole.

But, the advantages of CS props occurr at BOTH ends of the speed spectrum, AND (this is huge with $6.00 gas) a CS prop will allow you to fly MUCH more economically, by setting pitch and MP for economy. Even if you don’t care about price of gas, every plane Carrie’s limited supply of fuel, so, having the ability to save gas when needed is huge.

Which is why I’d highly recommend the OP to install a constant speed prop on this airplane. This will undoubtedly be a backcountry beast, where the advantages of CS props are important.

MTV

All agreed MTV but unfortunately the rules around the uniquely Canadian OM C of A dictate FP props only, less than 200 hp and fixed gear. Therefore I'm limited by the regs for my round tailed lady.

My Bearhawk is equipped with a 210hp Continental IO360 so it's not a direct comparison to your engine, just like GT's Maule, but we are talking props not engines. GT and I probably are running the same prop because the Franklin has the same crank flange pattern as a Continental.

The 88" Mac on my Bearhawk is awesome. The thrust is generates is killer but it is crazy noisy, it costs me 10mph in speed and I do have prop/ground clearance concerns. I mostly solved the clearance issue by putting the plane on 31" Bushwheels, now I'm in full poser mode. 5" extended gear and 29s is probably where I want to end up to keep my prop out of the dirt.

I like long props.

I put 50 or so hours on a Lyc O360 powered Bearhawk that had an 80" Mac C214 prop on it. It performed well. But here is the hitch: the Lycoming O360 has very harsh power pluses. That's the nature of four cylinder big bore engines. For that reason there are few big metal props that are harmonically compatible with those engines. The last thing you want to do it put a big metal tuning fork on your engine and end up shucking a blade. The only one I know of is the 80-84" Hartzall and it requires a heavy damper ring that mounts behind the prop hub. I looks like the only prop Mac offers for that engine is a 3-blade.

If I were in your position I would be looking for a long composite prop. I was in a very similar position as you when I was looking for a prop for that O360 powered Bearhawk I was flying. The WW 284 was my pick at the time.

If you don't care about harmonics, which I think is foolish, you could find a serviceable 2 blade prop off of a 540 powered 182 which would be an 82" McCauley. These props can be found for a somewhat low price which may allow you to run it for a while then when you were ready you could send it to WW and have them put their 284 blades on the hub for what I think is a very fair price.

whee wrote:I put 50 or so hours on a Lyc O360 powered Bearhawk that had an 80" Mac C214 prop on it. It performed well. But here is the hitch: the Lycoming O360 has very harsh power pluses. That's the nature of four cylinder big bore engines. For that reason there are few big metal props that are harmonically compatible with those engines. The last thing you want to do it put a big metal tuning fork on your engine and end up shucking a blade. The only one I know of is the 80-84" Hartzall and it requires a heavy damper ring that mounts behind the prop hub. I looks like the only prop Mac offers for that engine is a 3-blade.

That is VERY important information regarding four cylinder Lycomings, which was part of my initial question, as to what engine was being discussed.

As Whee noted, to install a Hartzell CS prop on parallel valve four cylinder Lycoming engines requires a harmonic damper assembly, which weighs about ten pounds (and, yes, it IS that heavy) and mounts to the back of the prop.

BUT, even with the damper assembly, maximum prop length is 80 inches. This prop is a Pawnee prop, which starts out at 84 inches. Some folks were using them on O-360s without a harmonic damper. A mechanic convinced Hartzell to conduct a vibration survey on that prop/engine combination. They found a destructive harmonic. Even adding the harmonic damper assy. till required reducing the prop diameter from 84 to 80 inches.

There’s no way I’d run an 84 inch HC2Y Hartzell prop on a parallel valve Lycoming engine. Talk to Hartzell tech for further info.

Now, the four cylinder angle valve Lycoming engines have a mass balanced crankshaft, so harmonics are very different.

MTV