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Post  cjuliano Mon Jan 09 2012, 20:29

which airfoil creates the most lift at slow air speeds
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Post  nitroairplane Tue Jan 10 2012, 01:58

Quite open question.
For low speeds I like flying nice under cambered wings.
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Post  cjuliano Tue Jan 10 2012, 15:35

can you show me a picture of that wing
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Post  nitroairplane Tue Jan 10 2012, 15:38

cjuliano wrote:can you show me a picture of that wing

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there ya go.
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Post  microflitedude Tue Jan 10 2012, 16:09

nitroairplane wrote:
cjuliano wrote:can you show me a picture of that wing

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there ya go.

Good stuff to memorize.
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Post  nitroairplane Tue Jan 10 2012, 16:34

Yes very important for the designer Smile
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Post  cjuliano Tue Jan 10 2012, 16:43

thanks
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Post  nitroairplane Tue Jan 10 2012, 16:44

Anytime just ask.
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Post  cjuliano Tue Jan 10 2012, 17:24

how do i post images
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Post  WingingIt74 Tue Jan 10 2012, 17:27

There also is a KFm airfoil. It's wild that it actually works.
off topic air foils Kfm-family-descriptions3
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Post  nitroairplane Tue Jan 10 2012, 17:34

WingingIt74 wrote:There also is a KFm airfoil. It's wild that it actually works.
off topic air foils Kfm-family-descriptions3


Those are crazy I have to use them one day!
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Post  nitroairplane Tue Jan 10 2012, 17:50


Looks interesting.
You will need to sand it smoother though.
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Post  cjuliano Tue Jan 10 2012, 17:51

think it will work well
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Post  nitroairplane Tue Jan 10 2012, 17:53

Yes once sanded.
What is it going to be on?
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Post  cjuliano Tue Jan 10 2012, 17:57

think it will fly
a 400g plane
with a cox .049 sure start
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Post  cjuliano Tue Jan 10 2012, 19:22

any one
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Post  John Goddard Wed Jan 11 2012, 05:00

I think you need to give the motor a fair bit of down thrust, it'll just keep looping otherwise.
Besta luck Very Happy
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Post  andrew Wed Jan 11 2012, 07:52

John Goddard wrote:I think you need to give the motor a fair bit of down thrust, it'll just keep looping otherwise.

John's made a very valid point.

If your motor is mounted as shown in the picture, the plane will be uncontrollable. Downthrust, or having the motor pointed downward relative to the angle of attack (the relative angle of the wing as the plane moves thru the air), is necessary to keep the aircraft from continually trying to climb, especially with high lift airfoils. Within a specific speed range, lift is related to the square of the velocity, so it goes up quickly as the speed increases. Before RC, freeflight planes had to be trimmed to fly on their own without pilot input. Downthrust was used as one of the trimming components. When under power and flying faster, the downthrust worked against the lift generated by the wing to keep the plane from ballooning or pitching up. It would be adjusted so the plane would fly in a slight climb. When the motor quit, the speed dropped off, as did the lift. But without the motor trying to pull the nose downward, the plane would be set up to fly in a fairly flat glide.

Downthrust is still used today on planes with lifting airfoils --- partially to compensate for lift to velocity squared relationship. When looking at your plane from the side, with the fuselage sitting as you think it will be angled in the air, the motor should be pointed slightly downward.

400g AUW is fairly light and the Surestart will haul it around quite well.

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Post  Kim Wed Jan 11 2012, 08:11

[quote="nitroairplane"]
cjuliano wrote:can you show me a picture of that wing

off topic air foils Intro_10

there ya go.[/quot

YEA !!!!!! for UNDER-CAMBER!!!!-----"Like Flying with Your Brakes On!"

off topic air foils Under-10
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Post  Kim Wed Jan 11 2012, 08:23

[quote="WingingIt74"]There also is a KFm airfoil. It's wild that it actually works.

Thanks a LOT, Travis. Just what I needed....something ELSE I got to try !!!!!
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Post  WingingIt74 Wed Jan 11 2012, 08:30

No problem, glad I can contribute to your madness Smile

Here is proof they work...
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Post  Kim Wed Jan 11 2012, 10:00

Cool! I'll have to check it out on the airport's WiFi.

Also, I wasn't challenging the performance claims..learned along time ago to keep my criticism to my self 'till I've got a little knowledge !

Wonder how easy this would be to apply to a slab balsa airfoil???? Looks like a little laminating and kazoom ! Off to the races !
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Post  andrew Wed Jan 11 2012, 10:44

Kim wrote:Wonder how easy this would be to apply to a slab balsa airfoil???? Looks like a little laminating and kazoom ! Off to the races !

The KFm airfoils are really quite interesting. Of course, the supporters love them and the detractors say the efficiency claims are bogus. I've built several electric foamys that use the KFm1 and KFm2 foils and they do work fairly well, particularly at the slower speeds we fly.

I build using Dollar Tree Readiboard with the paper peeled off, so with a little care, the leading edges can be nicely rounded. In the attached pic, I use Scotch storage tape across the area 1-2, then roll the panel over toward the beveled side. What's left of the bevel crushes and the LE with tape is round. The "step" is usually 3/16" or 1/4" square balsa and also serves as a spar. Two pieces of foam, one balsa spar, a little glue and a strip of tape --> your done. Ta-da: you have a wing for 50 cents.

off topic air foils Monoko10
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Post  Kim Wed Jan 11 2012, 11:24

andrew wrote:
Kim wrote:Wonder how easy this would be to apply to a slab balsa airfoil???? Looks like a little laminating and kazoom ! Off to the races !

The KFm airfoils are really quite interesting. Of course, the supporters love them and the detractors say the efficiency claims are bogus. I've built several electric foamys that use the KFm1 and KFm2 foils and they do work fairly well, particularly at the slower speeds we fly.

I build using Dollar Tree Readiboard with the paper peeled off, so with a little care, the leading edges can be nicely rounded. In the attached pic, I use Scotch storage tape across the area 1-2, then roll the panel over toward the beveled side. What's left of the bevel crushes and the LE with tape is round. The "step" is usually 3/16" or 1/4" square balsa and also serves as a spar. Two pieces of foam, one balsa spar, a little glue and a strip of tape --> your done. Ta-da: you have a wing for 50 cents.

off topic air foils Monoko10


Well... cool....Item # 37,320 on "Kim Lists of Projects to Try/Complete Before He Croaks" .... !!!!!!!!!!!!!!!!!
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