Bending the prop tips at 90 degrees
 

i have some club members who think by bending the very tip of the prop 90 degrees on the gws props creates more prop effiency. is this true? if so how much. i would think that if this is the case, all prop driven planes would have this.
d

RE: Bending the prop tips at 90 degrees
 

This is very simple to demonstrate...
Have the club members who "think" this could possibly work, SHOW it works using their stuff.. not yours. :)

RE: Bending the prop tips at 90 degrees
 

Tall Paul
They do have them bent. I don;t see a big difference as i have tried it. It is the silliest idea i have ever heard

RE: Bending the prop tips at 90 degrees
 

Yea I do have to agree with you that this is an extremely dumb idea. Another way to tell if little experiments like these actually work is to look at manufacturers. If it worked, then they would have had them out on the market years ago. Maybe they just like the look of the prop shaped like that.

RE: Bending the prop tips at 90 degrees
 

I'd be interested in the criteria these guys use to make the judgement of "better"... ???

RE: Bending the prop tips at 90 degrees
 

Would this be an attempt to put a Hoerner tip on each of the 'rotating wings' on the prop? Such tips reduce the vortex losses, increase efficiency, etc. on aircraft wings, and maybe the proponents' rationale is that Hoerner tips would benefit a prop as well.

RE: Bending the prop tips at 90 degrees
 

In FS airplanes, it's called a Q tip (Q for quiet?) propeller

Aerodynamic improvements include a reduced diameter and decreased tip speeds. This results in quieter operation and reduced tip vortices. The 90° bend reduces the vortices that, on traditional blades, pick up debris that can contact the blades and cause nicks, gouges and scratches.

Sounds like a marketing ploy to me :D

http://www.hartzellprop.com/product_...pport_faqs.htm

Cheers!

Jim

RE: Bending the prop tips at 90 degrees
 

I can see their point with reducing the tip vortices, but not with a 90 degree bend. Thats not a very efficient angle to place it at. Also, props are designed to have the gratual taper from root to tip. This is the most efficient way for a prop to be designed (with today's information and technology). But an increase in tip speed, which would happen if you bent the prop 90 degrees, would generate a a bit more thrust, but I don't think that boost is worth all of the trouble and the saftey issues.

RE: Bending the prop tips at 90 degrees
 

The benefit is real, both in noise reduction and efficiency gain, but the improvement in props in our RC planes would probably be mostly negligible. The reason 90 deg. bends aren't used everywhere and/or aren't bigger is the mechanical trade-off. Adding a 90 deg. bend creates significant CF induced moments in the prop blades, so you have to strengthen (read as thicken) the prop, which of course is not efficient- it's a trade-off that has to be evaluated for each design.

By the way, adding these bends to RC props is DANGEROUS for the reason described above. The props were not designed (the normal ones anyway) for the added CF induced bending stresses, so you risk prop failure by adding this bend.

DON'T DO IT!!!!!

RE: Bending the prop tips at 90 degrees
 

I need to see a photo of one of these things...

RE: Bending the prop tips at 90 degrees
 

RE: Bending the prop tips at 90 degrees
 

I'll try again [sm=angry.gif]

RE: Bending the prop tips at 90 degrees
 

That small difference at the tip makes a measureable difference in performance?
It might be possible in full-scale, but models are so seldom flown for true performance/efficiency, I doubt the alteration would be worth the effort.

RE: Bending the prop tips at 90 degrees
 

I remember seeing one of the carbon fiber prop makers sells props for rc with those tips on it... can't remember who made them though...

RE: Bending the prop tips at 90 degrees
 

http://tntlandinggear.com/store/shop...e_aircraft.htm

These particular props probably do not increase efficiency much (if any), and they certainly do not reduce noise levels, but they do add noticable stability in hovering-type maneuvers. This is due to increased prop normal force, according to an aero engineer whom I asked about it. I know I felt a HUGE increase in high alpha/hovering stability when I switched to a Prince prop for 3D.

RE: Bending the prop tips at 90 degrees
 

Wait wait wait. This is the cost of one prop? At first I though you put up a link for full scale props, but I realized it wasn't. Are they usually that expensive? I know that it is cabon graphite, but wow. There is no way that I would pay for a $200 prop.

RE: Bending the prop tips at 90 degrees
 

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RE: Bending the prop tips at 90 degrees
 

From several people I have talked to that use the Prince P-Tip props as available from TNT:

They are LOUD, and they pull. HARD.

I know I will be trying one after my DA50 is broken in.

RE: Bending the prop tips at 90 degrees
 

I can't seem to find any pictures or descriptions of them, but I thought I read something a while back about props with blades curved backwards in an arc. Not just the tips, but the whole blade in a parabolic-like shape. Apparently this worked well on some turboprop planes or something, I'm not sure. That's what I thought you meant before I saw the pictures of what look like winglets on the end of the prop blades.