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Hand propping versus Horsepower options

zenairdave

zenairdave

Registered User
Ontario
No, not another how to hand prop question.

I am considering a lighter aircraft with a goal of 750 lbs empty weight but with 150ish hp. Something along the Super Cub, Decathlon lines. Those planes routinely are 1000 lbs plus so it will take drastic weight reduction to get there.
Simple weight reduction (if not needed) is drop the electric start and generator like many Cubs and Champs. I don't have any issues with the A65, C85 or even O200 that I am hand propping(small engines) but at some point, increasing engine size has to make for an engine that you would rather not 'swing' .

So the question is not how big of motor you once started but rather, how big of motor is reasonable if the only way to start it is flipping?
I have never swung any other bigger or Lycoming motors , and hence the question.

Thanks

(and yes, it is a given, almost no interior panels, instruments, radios, ELT's etc.)
 
I know of IO-520's being hand propped so I don't think any four cylinder should be a problem. It comes down to what you can handle (bad back or shoulders?) and what you are comfortable doing (training).

Web
 
The worst engine I ever hand propped was a stock Lycoming O-360 with a short, lightweight wood prop. The lack of prop mass and inertia makes a big difference. An O-320 with a long prop shouldn't be too bad, as long as you can reach it reasonably.
 
I propped a heat soaked io360 with 3 blade hartzell. Counted my fingers after it lite off


Sent from my iPhone using SuperCub.Org
 
An O-320 or O-360 is a piece of cake to prop, once you first learn how to start them. I’ve propped larger engines, but wouldn’t want to do so routinely

MTV
 
Used to hand prop a 150 HP Super Cub all the time. I’ve propped R985s on AgCats and my Howard many times. Size isn’t so much a problem, prop position, flywheel mass, and compression ratio are the keys.


Sent from my iPad using Tapatalk
 
I've hand propped various airplanes from time to time but refuse to do it now. Two of my friends who were very experienced have had props kick back and whack them on the back of their hands. I have a Catto prop (which is very light) on one of my planes, and no way would I let someone hand prop it. You need to have a heavy mass to swing. Years ago I let the Flathead Forest Supervisor hand prop the Cessna 206 we were flying that day. Stupid! He said he could do it, and he did. Normally he flew a desk.
 
I've hand propped lots of engines...big and small. The absolute worst and most scary was a volkswagen in a Sonerai! Easiest was a 985. Like said above, mass of the prop has lots to do with it...Are you planning on higher compression, or other performance mods? I don't know how comfortable a Catto or some other really light prop would be. Use your head and you shouldn't have any problems.
JH
 
stewartb said:
Targeting 750# would be much easier with a lighter engine.
Click to expand...

As I was reading this thread, I was thinking "Man, I would NOT want to try hand-propping my Rotax 912ULS, with 2.43:1 gear reduction system and light-weight composite prop... Not sure it would be possible to get the engine spinning fast enough to light off... LOL

Fortunately, it's got a full electrical system and starts quite easily, so not something I've had to lose any sleep over.
 
Remember that the taller the landing gear the greater the prop angle is. Prop at the 6 o'clock position might be 1 to 2' closer to your legs then the 9 o'clock position if your out front

Glenn
 
stewartb said:
Targeting 750# would be much easier with a lighter engine.
Click to expand...

Yes it would but I already have that with a Clipwing J3 Cub with O200.

Looking at a different mission with more power and more wing. Not as easy to get the weight down.
 
Since some mention of Catto's is being made in this thread:

I hand prop a high(er) compression O-235 with a Catto 76" prop. It can be a pain the a$$ some days, but the prop is not a problem. I would not hesitate to prop a 320 with a Catto, and it would probably be easier than what I do now...
 
I've never propped a plane with a Catto prop, but I've propped several O-360a with MT composite propellers. That's best done wearing a glove, since the trailing edge of those props is pretty sharp, but I've done it bare handed.

I always prop from behind if at all possible, in any case. To make that work, you need to index the prop so it stops at 10 and 4 o'clock, as viewed from in front.

Aviat started indexing Husky props at 12/6 years ago, and those are not friendly to hand prop, though I've done it. We re-indexed those props for that reason. The good thing about composite props is that they eliminate most vibration issues on these engines, so re indexing is not a big problem.

MTV
 
I prop my high compression 0-200 with a 78” catto no problem and my pacer with a o-320 is no problem either


Sent from my iPhone using SuperCub.Org
 
Unless you're committed to a lycoming, consider the Yamaha Apex motor to save about 100 pounds, and still get 160-300hp...
 
Good luck making 750lbs. You will be lucky to make 900lbs empty with an O-320 unless you sacrifice everything that makes the plane easy to live with.

Lil Cub is a purpose built machine for short local hops and competition. You don't want to spend $$$ on a build so that you can only go a few miles from your home base at 65mph cruise speed.
 
Around here most 150 hp supercubs are around 1200 lbs. Very light non electric ones might go at 1,000 lbs. If you want a 750lb plane don't even consider a Super Cub. How much does you J3 weight empty?

DENNY
 
Denny, my J3 is around 735 empty (book weight) but that's probably optimistic. On top of that, the J3 has what I'd consider the bare minimum for a flying machine to be useable and even that is debatable. Add a baggage you can use and some big tires and it's probably around 800# if you put it on scales.

For a 150/160 horse plane I'd target 1000lbs. There's a few guys out there with planes that light and they work great that way. Another thing to consider is that 1000lbs is with some pretty heroic measures in the build process like drilling out every piece of channel, lowered floorboard mod, going thinner on boot cowl and leading edge material, no electrical system, no lights, and almost zero instruments. Basically a big J3 in essense.

The point is that a 750lb 150hp cub is a dream. It's never going to happen. Hell the engine is 200lbs all on its own so it would be pretty nose heavy at that weight.

BUT I will say a light cub is a fantastic thing. All this talk of shock absorbers and big tires is cool but when you're flopping 50% less aircraft weight into the ground the bungees and little 26's work just fine. I've muffed up some landings pretty good and still had respectable results just because there's so little amount of plane to get slowed up and stopped.
 
Hardtailjohn said:
I've hand propped lots of engines...big and small. The absolute worst and most scary was a volkswagen in a Sonerai! Easiest was a 985. Like said above, mass of the prop has lots to do with it...Are you planning on higher compression, or other performance mods? I don't know how comfortable a Catto or some other really light prop would be. Use your head and you shouldn't have any problems.
JH
Click to expand...
Yes the PW radials are pretty easy prop. Low compression and plenty of flywheel. You also get lots of choices on prop position. Nine, over the course of two revolutions.
 
PerryB said:
Yes the PW radials are pretty easy prop. Low compression and plenty of flywheel. You also get lots of choices on prop position. Nine, over the course of two revolutions.
Click to expand...

The most fun one was underneath and behind, while on floats.
JH
 
What could possibly go wrong.....? Besides the engine starting as you subsequently fall off.
 
I did it once on a Beaver floatplane 2-blade. Dumb me had let the battery get low or it was too cold +20F and snow. Rope with loop over one blade pulled a few times facing into the shore. Started because we put a coleman cook stove under the engine with tent tarp over the top. The battery was old plus still in the rear and the chief pilot thrifty.

Gary
 
180 on floats while drifting downstream rapidly on the Skwentna River... Not intentional and not fun....
 
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