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Old 03-15-2005, 01:13 AM
JonC's Avatar
JonC JonC is offline
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Join Date: Jul 2004
Location: Mountain View, CA
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Default Winglets on a prop?

Ok, first off, im not an engineer, nor did I stay in a holiday inn express last night. So, take a few shots of your favorite drink and then maybe you will understand where I am going here...

Basic aerodynamics say that airfoils generate significant spanwise flow as you approach the end of an airfoil, which in turn creates vorticies at the tip of the wing, causing increased drag and decreased lift... a lot of planes have benefited from having winglets fitted to help disipate the spanwise flow, and thus the vorticies and drag, Correct?

So, why not add small winglets to the tips of a prop since they are just twisted airfoils.. if the same theory applies... it should possible to get more thrust out of a lesser horsepower engine due to the decreased drag on the blade tips?

Just some random rambling/thinking.
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  #2  
Old 03-15-2005, 02:20 AM
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levansic levansic is offline
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Location: Tehachapi, California
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Default Prop winglets...

That sounds like an interesting idea, but the drag penalty would probably sap way too much power from the engine, negating the use of a lower output engine.

It's late, so I'm not quite thinking clearly right now, but what I mean is that winglets on the prop would contribute little if anything to thrust, but would definitely contribute to drag as the prop tips travel quite fast. The winglets on the EZ's act as vertical stabilizers and locate the rudders, so they have a functional purpose that is tied to providing drag, not lift.

-- Len

Last edited by levansic : 03-15-2005 at 02:30 AM.
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  #3  
Old 03-15-2005, 03:30 AM
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John Slade John Slade is offline
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Default

Interesting. One of the planes (VariEZ, I think) in my hangar has exactly that. I was looking at them only yesterday and wondering....

I'll take you a picture in the morning.

I don't think science has finished inventing yet.
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  #4  
Old 03-15-2005, 05:10 AM
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David Staten David Staten is offline
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Location: KEFD, Houston Area, Texas
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Default You can buy one...

Quote:
Originally Posted by JonC
So, why not add small winglets to the tips of a prop since they are just twisted airfoils.. .
They are already on the market. Hartzell sells the "Q-tip" propeller.

The following is a paste from the AOPA website regarding the Q-tip props they put on the "Win A Twin" sweepstakes of recent

Quote:
Originally Posted by AOPA
What about those Q-tips, you ask? Are they purely cosmetic? Hartzell says there are two advantages. One is that the propellers' normal diameters are reduced by one inch. This keeps dirt and small stones farther from the blade tips, and keeps tip erosion during ground operations to a minimum. Noise reduction is another plus. The curl of the Q-tip acts much like a winglet, smoothing out the vortices — and therefore the noise — caused by low-pressure air moving to high as the propeller tips reach the supersonic speeds of high power settings.

But the Q-tips do have an undeniable ramp appeal. They get the looks, get the comments, and it's difficult to resist touching them. And how many times do we hear the wisecracks about landing gear-up? Always. They invoke the story about a hapless flight standards district office official who, upon spotting his first Q-tip propeller, began writing up its pilot for a violation. "Honest, they're supposed to be that way!" came the defense. The report was allegedly filed, and the case was heard. In the hearing, the propeller manufacturer gave a presentation about its line of Q-tip props, and the ticket-happy official received his comeuppance.
.
Also, from the Hartzell Website..

Quote:
Originally Posted by http://www.hartzellprop.com/product_support/support_faqs.htm
What is a Q-Tip propeller? What are its advantages?
Q-tip propeller blades are formed by bending the tip section of the blade 90° toward the face side.

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.
.
Dave
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  #5  
Old 03-15-2005, 07:21 AM
Riseguy Riseguy is offline
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Join Date: Apr 2004
Location: Greenwood,IN
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Default You can buy one

Prince P tip.
I got one with 1 inch less pitch than my Catto. The Prince is about 5 MPH faster at the same RPM. and about 1/2 the weight of the Catto. The Catto is a 3 blade. The Prince P tip a 2.
I am in the prosess of weighing Cool for weight savings, and function.
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  #6  
Old 03-18-2005, 10:53 PM
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levansic levansic is offline
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Quote:
Originally Posted by levansic
...It's late, so I'm not quite thinking clearly right now, but what I mean is that winglets...
I keep telling myself not to post when I'm up too late at night, because I come across as an idiot.

I honestly was picturing a miniaturized end of a Cozy wing with a big honking winglet at the tips of the prop. I'm glad to see that I was really wrong. My friend Google showed me that the Prince P-tip looks really cool. Prince Aircraft's Price list, actually a formulary, shows that they make 3-blade props, but charge a 3x premium over their two blade props.

-- Len
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  #7  
Old 03-18-2005, 11:04 PM
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Dust Dust is offline
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Default

just emailed them to verify 3x, not x/2x3
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