Prop makers?

I couldn't either. If you're going to use one of these, you'd better make sure there is some way to get a lot of air moving over the engine. The usual test clubs have short, wide, steeply pitched blades to do this.

 

I have an article by Michel Colomban that I translated from french here
http://www.homebuiltairplanes.com/f...t=5622&page=76&p=432780&viewfull=1#post432780

The quality is quite low but PM me for a better copy.

Also use "wood club dyno" in your google search and you should get more hits.

Shannon.

Edit: I might have the wrong end of the stick here and have the wrong idea of what you are after?

 

I have a spreadsheet that can calculate hp absorbed by a certain Effel prop, or calculate the size eiffel prop to absorb a certain hp.

View attachment Eiffelclub.xls

 

Thanks for jogging my memory.. I raise you the version I picked up from somewhere....

 

Uh-oh, another long thread I now have to read...

 

That f!@#$%^& insignificant tower in Paris keeps getting in the way of my web searches on this subject. ;-)

 

Those put a weird asymmetric load on your crank shaft that at the very least can wallow out your front main bearing. IIRC the Cub that was flying with an Everel prop a couple years ago was wrecked over that very reason.

 

eiffel propeller -tower

 

One bladed propellers have been touted to be more efficient, But there is more to consider, what is it going to do to your motor mounts and engine bearings?

 

The blade is balanced side to side but it has asymmetrical thrust loading so it needs a teetering hub bearing like the Cub prop mentioned.

 

This article is kind of interesting:
https://www.aircraftpilots.com/tutorials/groundschool/blanik.html

 

I saw the counterweight come off a single bladed RC model like a bullet. I wouldn't do it. Folding props have a history of problems on piston engines. I wouldn't do that either. The difference in drag of a feathered Hoffman prop at 50 kts is not detectable by me. The main advantage of the Hoffman prop is the cockpit adjustable mechanical low/high pitch settings which make takeoff possible in a heavy motorglider.

 

Aircraft Propeller Design by Fred Weick, the NACA 212 guy. There's also a print on demand available in abebooks.

Hovey's prop book is on a VJ24W owner's website, along with one by Shubert.

The folding single blade props fixes some issues that they have. I wouldn't want to use a fixed single blader myself.

 

Seems like if they can make a feathering prop that survives a piston engine, they should be able to make a folder that does, which can probably have the bearings a little further apart. As far as counterweights go, I'm sure they can be made quite safe if the design is right. BTW, I've seen a blade break off a two bladed RC model prop like a bullet. It's a good thing that the guy who was hit on the back was wearing a heavy leather jacket. I guess it wouldn't have gone as FAR as a counterweight, but it probably went faster, at least at first. What percentage of performance degradation do you think you could detect?

 

I can feather the prop or unfeather it back and forth in a second with the prop lever. No difference that I can detect.
I can detect the dramatic effect of the dive brake lever and see the vsi go to 2000 fpm. I can't really detect the different glide ratio of say from 25 degraded to 20 without instruments or a clock. With a motorglider who cares? It isn't a glider.
Is the feather prop worth $12k? A very narrow fixed prop could be made with some almost feathered permanent root fairing cuffs if desired, I suppose.

 

Composite single balde props would probably be OK, the Everel prop had a problem of keeping it in balance as the wood adsorbed and lost mosture

 

If a motorglider isn't a glider, what do you call a good glider or sailplane that's able to launch itself?

 

There are only motorgliders or pure gliders. Pure gliders don't launch themselves.

 

Some footlaunchers are glaring at you, BB.

 

Snob! I won't let you ride in the S-10! ;-)