180 Hp Prop problem and Smith Cub Builder Offer

[GeneHerzog]

I am half finished (hope to finish in April) with a Smith Cub and have gotten a tremendous amount of info from this site. I really am just posting this to say that as payback I will answer any questions I can regarding this project so far. The build site is a hangar at Sulphur Springs just down from the American Legend Aircraft hangars and the personnel there have been a tremendous help. As a first time builder, I probably can't help with technical questions but may have experienced some problems (and possibly solutions) before someone else who is currently building one.

My biggest problem has been trying to get past the Sensenich fixed pitch prop versus hollow crankshaft 0-360 engine harmonic problem. I am currently waiting on McCauley to tell me if they have a 76-56 or something around there to use without the continuos operation limitation between 2150 and 2350 RPM. Anyone have a solution to that one besides the variable pitch prop from Brian Sutton? I know I could go to a "borer" prop, but want a compromise prop between speed and climb if I can.

 

[glassjet]

I know guys that have gone from borers to constant speed... it is unanimous... go with the constant speed.... especially if you want fast and short..... just my two cents worth...

 

[CptKelly]

Smith Kit Prop...

Gene,
I am using a Sensenich 80x48 wood prop with my Smith Kit, and it performs well. Wood props are beautiful, and don't have any harmonics problems. My XP-360 has a hollow crank too, but has no rpm limitations.
There are other brand of wood props that would work as well. If you would like to see how tis particular prop performs, come to NC and fly it.
I also have spoken to Mr. Tarver who is currently doing testing on his Aeromatic prop, and I certainly hope this works out.

Mike in NC

 

[jon s. blocker]

prop problem

Gene, I don't know if this will help at all, but on my C170 with an 0360/ hollow shaft, Hartzell C/S, the combination calls for a dampener on the prop. I know, I know, it adds 11 pounds, and right where you don't want it, but it works and it does away with the RPM restriction. This allows me to use an 80" prop. Move your battery back and you may be able to compensate for the added nose weight. We use a B&C light weight starter and it works great. Just another possible solution. Jon

 

[GeneHerzog]

Thanks for the replies guys. I know I can get a McCauley 80 or 82 inch (Borer) prop with a pitch of 42 to 48 inch pitch and not have any restrictions with the hollow crankshaft.

I was trying to find a way of getting more of a cruise prop like the Sensenich 76-56 in a McCauley or equivalent without the restriction. The constant speed option is out at this point. I know that is the best of both worlds. It looks like no one has found another answer except the wood prop.

Craig Catto who makes composite props for the Reno races and a lot of RV's says he will have a great prop available in about 5 more months. I can't wait that long myself.

Again, thanks for the replies.

 

[diggler]

delete

 

[GeneHerzog]

Diggler,

We built the engine at the Superior Build school and they only offer a hollow crankshaft engine which we plugged. The engine school was a great experience and I really believe they have improved the Lycoming engine to a great extent.

Didn't know about the restriction at the time we built the engine.

Which prop available would provide the best speed and reasonable climb performance without the restriction? The engine developed 189 static hp on the test stand. Has roller lifters.

Thanks for the interest.