Hatty

This topic has probably been discussed before, but I couldn't find anything. Is there any benefit to propellers with winglets or any other vortex reducing device? I'm guessing that there might be a velocity limit to winglets and that's why they aren't used on props, but I could be wrong. I'm also guessing that if they do improve performance, the prop would probably be susceptible to breaking at the point of curvature. If that's the case, what about raked tips?

What's your take on the whole subject?

I think I asked too many questions.

Sport_Pilot

They have used winglets on full scale props, but I don't know all the details. There is an STC to add winglets to existing props on certain aircraft, but I am recalling that the main benifit is reduced noise.

Tall Paul

A couple of my foamie 3D planes come with 10x3.8 props with small winglets molded to the tips.
Why?
Who knows?

mulligan

See this thread about Q tip props:

http://www.rcuniverse.com/forum/m_21...tm.htm#2191474

Hatty

Funny thing, I got a new plane this week and it had this type of prop on it. The first thing I thought of, after seeing it in person, was that it helps with hovering stability. I bet it had no aerodynamic benefits.

cyclops2

In my point of veiw the vertical winglet can also be seen as a airfoil fence. That would prevent the airflow from sliding to the end of the prop. Fences can boost efficiency by reduceing slippage.

There is a ton of centrifugal force generated by a prop on the air going around it.

airraptor

My Feedback: (66)

a 10" prop with winglets will act like a 11 to 11.5 size prop with out, while having the 10" prop amp draw on the motor

Hatty

Do you have any data to prove this, or are you just guessing? What companies make them?

N1EDM

My Feedback: (2)

What would be the difference between putting a winglet on a prop, as opposed to running the prop inside a duct?

Bob

da Rock

The blades in a duct experience only straightline airflow. That enough?

Hatty

I would think that a blade inside a duct wouldn't allow the formation of vorticies at all. Thats probably why you never hear about engine manufacturers (like GE or RR) worrying about vorticies. The only problem with a duct is that you cannot get the thrust that a large diameter, non-ducted blade can deliver.

Winglets technically only reduce the effect of voticies, not eliminate them. So, like airraptor said, its like adding wingspan with the same sized wing (for airliners that is). I don't know about props. I would like to see scientific data on this one before I start talking about the effect of winglets on props.

N1EDM

My Feedback: (2)

Thanks, Hatty. And, da Rock, I'm not sure what you're getting at??

Bob

da Rock

Protecting the blades in a duct creates such a different environment from exposed blades, that the "other" differences pale by comparison. It's basically apples versus salami.

airraptor

My Feedback: (66)

test it your self with same type of prop but one size bigger. watts vrs thrust

they do work same principle as the winlets on wings more lift with less wing. the only bad thing is one nick on the ground and the winget is gone

pimmnz

But the air is drawn in from the tips of a prop, not thrown out.
Evan.

da Rock

Do you have any references for that?

pimmnz

All those fancy wind tunnel/smoke things. Even a mate of mine who makes CF speed props, and tests them in a tunnel, has a simple smoke injector thingie and tells me the same.
Evan.

Ed_Moorman

My Feedback: (1)

I tried winglets on prop back in the middle 1980s on gas engines. As I recall, I did 18" ones for the G-38 and Webra Bully I was flyng and also a 22" for a Sachs-Dolmar 60cc.

I used Zinger wood props. I sanded the finish off the back side ofr the blade for a half inch or so then 30-minute epoxied on 3/8x1/2 maple motor mount stock. After the epoxy cured, I drilled and inserted small dowels or toothpicks with epoxy. Next, I used a Dremel sanding drum to sand the inside to a nice round shape. After shaping, I soaked the wood with thin CA. Some light sandng and I painted the prop in color with K&B epoxy paint. I used red and yellow.

Ground rpm was not much difference and I don't remember what it was. In the air, I did notice a good increase in climb and the prop seemed to bite more. As I recall, the rpm was lower, but the climb was better. This told me the prop was hangng on to more air, giving better performance.

Soon after I started flying mine, I saw some made from carbon fiber in pattern sizes. These didn't catch on. I think it was the cost vs. breakage factors.

I was always afraid to try them on small glow engine sizes because of the high rpm and the chance of slinging one off. I always made sure the sides were clear before starting and running up.

cessnat210

I'm going to try and build a wood prop like ED mentioned. I'll do some testing on it with my O.S. 65LA and let you know the results when I get them. It seems like its worth trying due to the fact there is so much debate.