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Airfoil shapes

Old 01-08-2006, 11:02 PM
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Sleeper-6
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Default Airfoil shapes

Hi, my Sterling Fledgling Is coming up on it's fourth or fifth re-birth. Mostly due to bring returned to kit form by me. It has evolved somewhat but still remained close to it's roots over the years. I'm looking to change the wing airfoil to something that will slow it down some and make it a more relaxed flyer. The problem is that there are so many airfoil shapes out there, Where can a Find a guide to help me pick the right one?
Old 01-09-2006, 03:25 AM
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BMatthews
 
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Default RE: Airfoil shapes

To slow it down ideally you should carve out about 1/2 the overall weight. But since that's probably a bit hard to do what you need is an airfoil with more camber than you have now. Consider going to something that has about 12 to 15% thickness and about 6% camber. That's a good compromise for our model sized stuff and will provide a higher maximum lift coeffient to let you loaf along at reduced speeds but not fall out of the sky.

Also remembe that some of your controls will need more travel since the slower speeds reduce the effectiveness. And higher camber wing sections flown at the higher lift coefficients at low speeds are more prone to adverse yaw effects from ailerons. To combat this you should design in a control linkage for the ailerons that induces a lot of differential travel with the up travel being at least twice the down travel.

Or consider switching to roll control spoilers instead of ailerons. That would be a cool experiment. Not as aerobatic but effective for general upright flying.

My suggestion would be one that I have on one of my RC assist old timers. It's the Gottingen 501. It has a great slow speed flight but a surprisingly good penetration ability when you put the nose down a bit. Not fast by any means but it'll punch into any reasonable headwind even when gliding.

You'll need to learn how to cover an undercambered wing for this as well.
Old 01-09-2006, 10:54 AM
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Sleeper-6
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Default RE: Airfoil shapes

That sounds like it would work. I was planning on using dual aileron servos mounted side by side in the center underside of the wing anyway, so differential movement would be a piece of cake. This plane was my trainer so learning to fly on it was quite an experience. My main complaint was that it took forever to slow the thing down for landings. It always wanted to fly fast no matter how far back I pulled the throttle. I have since been flying a Super Sportster and an Ultra Sport, I the Sportster is closer to the characteristics I would like to copy, if not a bit lazier for relaxed putt around the sky type flying. Thanks

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