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Propellers with winglets - are they any better?


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I have noticed that a few manufacturers are bringing out props with winglets on their tips. I heard that the French team introduced them in the world championships and the whole market has been gaga ever since. Has anyone tried them out yet? Are they the dog's danglies?

I understand the science behind winglets on commercial aircraft, but how does that translate to propellers? Does the winglet increase the swept area of the prop without increasing the diameter or is it all a marketing ploy?

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I've got the new turned up tips on my new parajet props and they make a massive difference............

The difference is that they look great (not that the carbon ones looked too shabby)!!!

The idea is that they are more efficient and quieter.

I would love to say that I was sensitive/experienced enough to feel or hear or measure a difference but I would be lying...............but don't they look nice? :D

Ian.

p.s.

The new props also benefit from interlocking hubs which stiffen the blades and reduce slipping

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I am not so sure that there is any other benefit than looking good.

But they are not worse thats for sure.

We can check the noise level in the field on the same day, same motor, by changing the prop, leaving the meter in the same place..

It should show some variation if any exists.

SW :D

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Do you have facility to measure static thrust as well?

Nice seeing your sound level post - it would be even more fabulous (read: that was fabulous) to correlate prop manufacturer size and type.

So many variables...

I've only seen one prop with the tip winglets so far (I got to massage it with some bicarbonate and superglue), and I think the center of winglet lift was canted somewhere ahead of center of prop rotation. I will assume by virtue of that prop having a winglet at all that it was engineered for a specific rpm to soundly and directly interact with and redirect the forces normally wasted as wingtip (proptip) vortice and therefor supersonic noise. It makes sense that they are quieter and make more thrust than a similarly pitched smae diameter prop and that's the goal of the winglets, er wingtiplets, er, thingies on the end of the prop.

I think in general they are a fabulous idea and would retrofit my current prop with stick ons in a second if I expected they would stay put for any length of time.

The winglets on an Advance Paraglider, modern jet, all do the same thing.

Imagine the curl seen here, getting put to use rather then getting left behind the wing, then use your mind to chop that wing in half and spin it ;-)

I secretly think they ideal prop would be a mixture of scimtar (a la macro) and wingtiplet, but with the wingtiplet integrated into a larger proportion of the outer portion of the prop disc. Even in my imagination though, that is prohibitively expensive...

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It is well established that Advance's winglets did not have the desired effect, but it became such a distinctive feature, that they now retain it for marketing and advertising purposes. The winglets on their competition gliders are miniscule.

The only paraglider to provide any convincing evidence that their winglets work are Bio Air Technology (BAT). There was an interesting discussion on the paragliding forum sometime back.

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A prop is just the same as a wing in most ways. A winglet at the tip reduces induced drag and increases efficiency. If you can keep prop tips subsonic and smooth the flow of air past the tip there will be a reduction in noise.

Less thrust required to drive a 'cleaner' prop = improved aerodynamic efficiency = reduced fuel consumption

One minor drawback is that these devices are 'tuned' to a particular speed for their efficiency and do less good as you move away from that prop rpm (or in the case of a wing - TAS - True Air Speed).

Winglets.jpg

RTEmagicC_51880079c2.jpg.jpg

whispertip_600.jpg

It even works with water.

Image1.jpg

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Am I getting this wrong or what?

Looking at the above pictures and converting the wings in to props the wing-lets would be on the front of the prop not on the back as they are now :?:?

Pete b

I do believe the man is right! On a wing the tips turn towards the low pressure area, but on a prop it's the reverse. I can only guess that it's like the draft excluder on a door, you can put it on the inside OR the outside.

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It even works with water.

Image1.jpg

That looks like the "where is that sandbar?" design.

I have a friend who buys from them.

They live in the shallow parts of the bay and don't charge a thing for the dynamic redesign.

You don't even have to slow down! It's automatic! ;-)

Richard/Norbert: Do you have any thrust or Db numbers?

My Advance winglet was indeed a bad example for function as it is more of a brand stamp, but the intent/goal of the winglet is to extract/redirect the energy from the tip vortices after all, so it makes sense that those little sonic booms getting changed into a thrust vector adds something, or extracts something in trade off for noise, as the design model may determine.

A draft excluder is probably as apt an analogy as any. It would get expensive tearing off a jet's winglet's after a crossed up landing. Top or bottom it's going to chop the wingwash vortice in half right?

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Well got my shiny silver props from Parajet and fitted em on the Volution ..Took off and levelled out at about 1000ft...It may be me but i eased off the throttle as i normally do..then eased a bit more with plenty of thrust there. they DID feel different.Mind you i may have been justifying the cost in my mind !!.Did about an hour and very pleased. The next evening had a fantastic 90 min...got back home for a splash and dash before sunset. Nill wind so forward launch towards some trees. Running as fast as i could (wheres the lift when you need it?) ,full throttle and do or die...you guessed it...slipped , and three carbon works of art shattered across a 100ft area taking the petrol cap off in the process and damaging the cage..DOH!!..Why isnt there more clearance between cage and props ? Ordered more but none in stock. Im going for fibreglass this time ..still with the winglets and hoping not to make same mistake/balls up again ! Reverse Launches Rooool !

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Perhaps the fact that no aircraft prop manufacturer, who spend millions on the most efficient design due to the high returns on efficiency savings from even the smallest percentage improvement, have produced them is telling? Just a thought.

Rob

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and three carbon works of art shattered across a 100ft area taking the petrol cap off in the process and damaging the cage..DOH!!..

How interesting..... :? Pete B might have an interesting comment to make there.

Dont fall over :D

Make sure the cap is screwed on properly as they do tend to go on cross threaded some times.

I thing the clearence on the prop needs to be addressed, on all models.

Pete b

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