Speed Mod Ideas

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Speed Mod Ideas

Postby av8rps » Sat Mar 07, 2015 2:06 pm

I see some doing fibreglass fairings and such for further drag reduction on our airplanes. So I thought I should share with everyone some ideas for reducing drag:

Start by looking at the old air racers like the Monocoupes and planes like Mr. Mulligan, etc, for ideas, as they pretty much have figured out how to get more speed from low horsepower high wing aircraft way back then.

I've always thought for the Highlander that it might be cool to make a fibreglass wing strut fairing that would clean up the area behind the strut (Monocoupe style) but to incorporate a flow fence for the top of the wing in the same fairing.

And some of the tail fairings they used back then also are worth looking at IMHO.

Bill Brennand, a famous air racer (the airplane he raced for Steve Wittman hangs in the Smithsonian today) is a very good friend of mine, and one night I asked him how to make our little airplanes fly faster. He suggested looking at the old air racers as they had a lot of success in making those old planes fly amazingly fast on little horsepower. So I thought I would share with all of you what Bill shared with me.

Paul S.
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Re: Speed Mod Ideas

Postby Johnny C! » Mon Mar 09, 2015 12:46 pm

Thanks!

john
There are many things that happen really fast when you are
flying an airplane. There is no sense in rushing any of the others.

I would much rather be looking down at the runway, than up at it.

Duane Sorenson & Rick Norton Gone West 6/8/09. Godspeed
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Re: Speed Mod Ideas

Postby SheepdogRD » Mon Mar 09, 2015 11:41 pm

av8rps wrote:I see some doing fibreglass fairings and such for further drag reduction on our airplanes. So I thought I should share with everyone some ideas for reducing drag: Start by looking at the old air racers like the Monocoupes and planes like Mr. Mulligan, etc, for ideas, as they pretty much have figured out how to get more speed from low horsepower high wing aircraft way back then....

Thanks, Paul -- that's a good idea. I looked up that Monocoupe Clipped Wing Special, and found an interesting site with a bunch of pictures: http://vintageaircraftmuseum.org/aircraft/flying/monocoupe-clip-wing-110-special-the-spirit-of-dynamite/.

One of the comments about the development of the aircraft is that they increased speed by decreasing the size of the main wheels and the tailwheel, and by adding wheel pants. That got me smiling, because those moves are opposite to what we’re doing. We're unlikely to give up our fat-tire addiction, and unlikely to shed the long gear with its additional leg (on the Extreme gear) or big external shock legs. But, looking at work done on the Monocoupe, we can put fairings on the struts, gear legs, bungees and shocks, and add fairings where those parts intersect with the fuselage:

Clip-wing-monocoupe_014s.jpg

Troy mentioned he was intrigued by the teardrop pants that don’t cover the tire at all, but just sit behind the tire and provide aerodynamic clean-up downstream. The ones I remember were on Arnold Ebneter’s E-1. He said (on www.http://thepropellerunderthebed.com) that using them meant he gained 10 knots of airspeed with 2 pounds of material. Imagine scaling these up to a 26” tire:

E-1-Wheel-Pant -2.jpg

Even with the small tire, there’s some risk of debris building up in that gap, or of gravel getting caught and chewing up a tire, so it would be interesting to see if there’s a way to mitigate that issue.

If anyone has done tuft testing, it would sure be interesting to see the videos and photos so we have a better idea where else we can reduce drag.
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Re: Speed Mod Ideas

Postby danerazz » Tue Mar 10, 2015 8:15 am

I just want to see 29" tundra tires with wheel pants.
Dane

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Re: Speed Mod Ideas

Postby SheepdogRD » Wed Mar 11, 2015 12:37 pm

danerazz wrote:I just want to see 29" tundra tires with wheel pants.

That’s the beauty of Arnold Ebneter’s idea. From the site I quoted above, “Reasoning that most of the drag came from the turbulent flow behind each wheel and tire, he decided to cover just the backs of those parts.” He used a football shape, as shown in the picture above. On a large tire -- say 26” diameter -- that would be a good-sized piece of fiberglass... or aluminum... or carbon fiber.

But what if, instead of a football shape, we opted for a teardrop, which is even more efficient aerodynamically? Here’s a draft of a 16” high shape mounted behind a 26” tire. This is riding 1-1/2” back of the tire, and extends about 16” behind it:

Tire-Trailers 1.jpg

Let's call them Tire-Trailers. They could be an interesting idea as a travel aid, perhaps mounted like the mud flaps discussed here: http://www.wingsforum.com/viewtopic.php?f=218&t=22777&p=41942. That mount might attach to both sides of the axle, and stay on when the Tire-Trailers are removed.

We’ve read about guys changing props or repitching props for competition -- or maybe just to STOL around. Seems like it wouldn't be much more trouble to unbolt the Tire-Trailers and leave them with the speed prop, or put them in the cargo bay.

It sounds like an interesting project, and I’d love to pursue it... but I need to get this bird flying before I do that.
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Re: Speed Mod Ideas

Postby av8rps » Fri Mar 20, 2015 1:54 pm

I thought I should show someone what kind of a wingstrut fairing I was talking about (if I wasn't clear on it earlier).

Here's a pic;

And now imagine if we could incorporate a flow fence on top of the wing that would work into the lower fairing? That was my original idea.


Also, I like the idea of the fairing behind the tire. Could probably help the bushwheel drag a lot.

Paul
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wing fairing from mister mulligan.jpg
Winstrut fairing from a 30's air racer
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Re: Speed Mod Ideas

Postby Johnny C! » Tue Mar 24, 2015 12:40 pm

Waht would the fence do for you?

John




av8rps wrote:I thought I should show someone what kind of a wingstrut fairing I was talking about (if I wasn't clear on it earlier).

Here's a pic;

And now imagine if we could incorporate a flow fence on top of the wing that would work into the lower fairing? That was my original idea.


Also, I like the idea of the fairing behind the tire. Could probably help the bushwheel drag a lot.

Paul
There are many things that happen really fast when you are
flying an airplane. There is no sense in rushing any of the others.

I would much rather be looking down at the runway, than up at it.

Duane Sorenson & Rick Norton Gone West 6/8/09. Godspeed
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Re: Speed Mod Ideas

Postby SheepdogRD » Tue Mar 24, 2015 10:58 pm

Johnny C! wrote:Waht would the fence do for you?

A flow fence blocks spanwise flow of air. In other words, it helps keep air flowing toward the back of the wing, instead of sliding off toward the wingtip. That can help make the control surfaces more effective, and can help reduce stall speed or at least make stalls less abrupt.

Tip fences, as used on the SuperSTOL, are a version of this idea. I've seen similar devices inboard on the ends of flaps and ailerons, too.

I've seen flow fences at the point where flaps and ailerons meet. That's harder to do on the Escapade & Highlander because there's no rib at that point (there's also no rib where the struts meet the spars). But, If flow fences were in a builder's plan, it wouldn't be too hard to add ribs before covering. Here's an example on David Horton’s N422CH:

N422CH-2r.JPG

... as discussed in this thread: http://www.wingsforum.com/viewtopic.php?f=218&t=23061
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Re: Speed Mod Ideas

Postby Johnny C! » Wed Mar 25, 2015 4:55 pm

Thanks for explanation.

John

P.S. Have we lost our edit
privileges?
There are many things that happen really fast when you are
flying an airplane. There is no sense in rushing any of the others.

I would much rather be looking down at the runway, than up at it.

Duane Sorenson & Rick Norton Gone West 6/8/09. Godspeed
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Re: Speed Mod Ideas

Postby av8rps » Sat Mar 28, 2015 8:19 am

Here's maybe a real easy fix for cleaning up some drag behind wing strut
[youtube]www.youtube.com/watch?v=SqB21fwG374[youtube]
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Re: Speed Mod Ideas

Postby av8rps » Sat Mar 28, 2015 8:33 am

Here's someones real easy fix for reducing drag behind forward wing strut;

[youtube]www.youtube.com/watch?v=qTtrGv9PWFw[/youtube]

I'm on an android notepad, so if link doesn't work just search for "Avid Flyer STOL wing wing strut turbulence" and you will see this gentlemans super simple test that proves his fix works. Probably cost less than 5 bucks and adds less than an ounce or two of weight

Paul S.
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Re: Speed Mod Ideas

Postby av8rps » Mon Mar 30, 2015 7:32 pm

Let's try and see if at a regular computer I can get the Youtube video to play? (Or at least I can provide a link to click on)


http://www.youtube.com/watch?v=qTtrGv9PWFw

[youtube]www.youtube.com/watch?v=qTtrGv9PWFw[/youtube]

Hmmm? Can't seem to get that youtube screen to show up here????
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