A prop absorbs around 5 lbs/hp as thrust so a 100 hp engine generates ~500 lbs force. Props are designed to accept that force as bending and torsional loading. So pulling on a prop by hand to move a plane would never exceed the service loads.
Bob H
A prop absorbs around 5 lbs/hp as thrust so a 100 hp engine generates ~500 lbs force. Props are designed to accept that force as bending and torsional loading. So pulling on a prop by hand to move a plane would never exceed the service loads.
Bob H
Is that per blade or for the whole prop? In either case a C-150 weighs more than 500 lbs.
I know we've decided that we are smarter than the engineers at the various prop factories and that you won't hurt (especially a fixed pitch) prop by pushing or pulling but keep the force as near the hub as you can even in a fixed pitch prop. If you are rocketing around with a variable pitch or ground adjustable I strongly suggest you follow the manufacturer's instructions and invest in a tow bar and get in the habit of using it.....AND TAKING IT OFF EVERY TIME YOU PUT IT DOWN! I have a couple of horror stories about props and tow bars...(Think not only tow bar but New MT prop AND ENGINE TEAR DOWN!! at $40k+). My beloved customer's broke the habit. I had to fix it...and the McCaulley on the Mooney wasn't much cheaper... It's NOT the way I wanted to earn my living..
The leverage of pushing and pulling really does have a detrimental effect on the blades (to some extent even of a fixed pitch prop) and their setting especially when they don't have the benefit of centripetal force to lock all the pieces in place as they do when in their "working" mode.
I would say it depends on the size of airplane, what it is setting on, and how far you plan to move it. My little airplane at 400 lbs takes very little effort to move it on the hangar floor a foot or two. But put it on an incline in the grass and its a bitc$ to move. Now take something like a twin engine sitting on concrete.