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Old May 08, 2012, 01:40 PM
Jack
USA, ME, Ellsworth
Joined May 2008
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Another regular here, viking60, has spent quite a bit of time and effort reducing the drag on KFm wings and improving their performance. A lot of his work can be seen here and at the links to his web pages that are in that thread.

DANCER Series: 39" to 62" Wings... - http://www.rcgroups.com/forums/showthread.php?t=860461

You'll notice the Godfather of KFm wings,Tony65x55, posting in the early parts of the Dancer thread. Viking's involvement with KFm wings goes back to the time when it was all getting started.

The leading edge thinning and tip shaping techniques seen there are some of the things that are going to put the performance of the KFm winged gliders much closer to conventional foil gliders.

The Altitude Limited Electric Soaring (ALES) competitive glider flying events have been gaining is popularity in recent years. The ALES events center around AMA club flying sites that have a good interest in gliders. Here are the rules a typical ALES event (some minor changes are found from place to place):

http://www.rcgroups.com/forums/showa...3&d=1330384272

A simplified description of the ALES event is that it is a Man-on-Man competitive flying event where a number of motor gliders (without regard for size or quality) are launched simultaneously against a 10 minute timer. There is a device on each plane that cuts off the motor at a run time of 30 seconds or at the altitude of 200 meters (656 feet), whichever happens first.

The goal after cutoff is to fly on thermal lift for the remainder of the 10 minute period and land on or as close as possible to a marked spot. The closer to right on the 10 minute time limit the landing is the better the score is, and bonus points are awarded for how close to the marked spot the touchdown was.

A series of flights are flown and the winner is the best score and the end of it all. And in the end it is the pilot that finds the lift to keep himself airborne for the 9:30 seconds after cutoff and that also does the best job of nailing the landing as the 10 minute timer expires and while also landing on the marked spot is going to be the winner. So there are elements of luck, skill, and plane quality all intertwined to make it interesting.

As the ALES events started being flown the Hobby Zone Radian was a frequent entry and was winning and placing high in events. And, as you know, the Radian is a molded foam mass production glider that was a wonderful flyer, would thermal well, and was a lot of fun to fly.

The Radian could be bought for a little over $125 or so and was doing a great job against some much more expensive and much larger planes. So ALES was bringing a lot of interest and new participants into the hobby. It was one of the first events for glider pilots that did not emphasize or favor much more expensive planes and the more experienced and skilled pilots.

As i got started with gliders two springs back I was also reading about ALES events. It looked to me as if that, with some more effort, a KF winged glider might have a chance to be competitive in ALES events.

I haven't gotten any further along with actually attending or competing in any events (none are held in my immediate area as far as I know). And that it would be a challenge for me with the performance I have at hand, I still think it would be fun to fly the events. I look forward to the day when KF wings and scratchbuilt foam airplanes at seen aret these events.

Jack
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Old May 08, 2012, 02:16 PM
RC beginner
New York
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as usual you post the most interesting material. i would also be thrilled to see a kf wing place in one of those events. btw isnt >400' verboten by ama rule?
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Old May 08, 2012, 08:33 PM
Jack
USA, ME, Ellsworth
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Quote:
Originally Posted by dave1993 View Post
as usual you post the most interesting material. i would also be thrilled to see a kf wing place in one of those events. btw isnt >400' verboten by ama rule?
Jeez, you got me on that. I don't fly at AMA clubs because there are none handy to me. And maybe I don't like the level of supervision and rules and stuff they have to have at those kinds of places either.

Maybe they make an exception on the 400 foot rule for these events?

If you get to 656 feet at the 30 second mark, you have 9:30 (570 seconds) left to fly for the thermal duration portion. My Big Blue, at it's best of 2.8 FPS and no thermal help, would be on the ground in 203 seconds. So I'd really have to find some thermal help to have a chance.

The "gold standard" floater at 1.0 FPS would, at least in theory, be good for a 656 second glide with no thermal help. So he would have to rush his descent to get it on the ground at the 10 minute mark. That is really an advantage for him. He could just over over and hang around the landing spot and wait for the time to run out while I would be out scouting for thermals and hoping I can get enough lift from where ever the thermal is and still get back to the landing place.

It really is a fascinating event. They have their own forum here now:

Altitude Limited Electric Soaring (ALES) - http://www.rcgroups.com/altitude-lim...ring-ales-770/

I read the Electric Sailplanes forum occasionally, and maybe Sailplane Talk. It can get pretty funny over there when the thermal only purists get up on their high horse and start their "it is not a sailplane if it has a motor" thing. They actually make snide remarks about planes with motors and and even the people that fly them.

My feeling on it is that they have their motors in a box on the ground and I have mine in the nose of the plane. And I really prefer it that way. When I get caught downwind and am struggling to get back, I can use the motor. If it was a thermal only plane the alternative would be to watch it go down in the woods and then to have to go and find find it.

In Maine, the best thing to do when that happens is to go directly to one of the boggy spots that are swarming with gnats and black flies and walk around in the ankle deep mud for an hour. Then give up and walk a bee line back to your car and you'll find it on the way back there. Seems like no matter how hard I try I cannot reverse the "find the plane in the woods" process.

Jack
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Old May 09, 2012, 01:43 AM
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Victoria, BC, Canada
Joined Apr 2001
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The 400' rule applies within 3 miles of an airport and is an AMA rule because FAA requires aircraft to fly above 500' except when landing. However, the FAA provides guidance that model aircraft should (not must) remain below 400'.
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Old May 09, 2012, 08:48 AM
just Some Useless Geek
Chicagoland
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Quote:
Originally Posted by jackerbes View Post
...So there are elements of luck, skill, and plane quality all intertwined to make it interesting.
Aaaaand that's where you lose me. I used to try my hand occasionally at model rocket competition (altitude, duration, spot landing, yada yada). I found that the luck element in far too many of the classes made actual competition more of a joke than a contest. No fun at all.

I fly ribbon and full contact combat because it's pretty simple and the rules are straightforward: he who lands last/has the longest ribbon/is still flying wins. There are other competitive R/C air activities I might be slightly interested in, but investing a buck and a quarter and lots of time practicing for a competition that could be decided by a coin toss isn't one of them.

No doubt there are plenty of people who find this ALES stuff enough fun to justify their involvement. I just can't imagine calling this a "competition" when luck has any part of it. Oh, well.
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Old May 09, 2012, 09:46 AM
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Quote:
Originally Posted by jackerbes View Post

The "gold standard" floater at 1.0 FPS would, at least in theory, be good for a 656 second glide with no thermal help. So he would have to rush his descent to get it on the ground at the 10 minute mark. That is really an advantage for him. He could just over over and hang around the landing spot and wait for the time to run out while I would be out scouting for thermals and hoping I can get enough lift from where ever the thermal is and still get back to the landing place.

Jack
Jack,

I agree with your comments, but there's one other tidbit which I'd like to add into consideration:

The guy with the ideal floater still has another factor that he is still up against... for there to be rising air - thermals - there also has to be a lot of sinking air replacing those columns of rising air. Where I fly up here, it seems there's very little of the in-between 'dead' air that's neither rising or sinking. So the challenge still involves staying out of the sinking air that's being sucked into the base of those rising columns of air as much of the time as possible, while locating the warmer 'up' air.

This is also a constant background factor when trying to do comparative consecutive 'test flights', as the variation from warm rising air to cool sinking air is an ongoing background process that, in my observation, may be far more significant when doing non-powered 'glide duration' tests of different wing configurations.

So the simultaneous launch is the great equalizing factor in the ALES competition. Everyone starts in the same variable 'river of air' that's moving through the flying site, offering ever-changing challenges.

Some days, once you're above 600' AGL it seems like the whole sky is going up & there's not much for sink air up there, and the challenge is to keep your aircraft down within sight. (Ahhhhh, our aging eyes offer their own challenges into the game for some of us....)

Viking
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Old May 09, 2012, 12:49 PM
Jack
USA, ME, Ellsworth
Joined May 2008
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Quote:
Originally Posted by A Useless Geek View Post
Aaaaand that's where you lose me. I used to try my hand occasionally at model rocket competition (altitude, duration, spot landing, yada yada). I found that the luck element in far too many of the classes made actual competition more of a joke than a contest. No fun at all.

I fly ribbon and full contact combat because it's pretty simple and the rules are straightforward: he who lands last/has the longest ribbon/is still flying wins. There are other competitive R/C air activities I might be slightly interested in, but investing a buck and a quarter and lots of time practicing for a competition that could be decided by a coin toss isn't one of them.

No doubt there are plenty of people who find this ALES stuff enough fun to justify their involvement. I just can't imagine calling this a "competition" when luck has any part of it. Oh, well.
I think the biggest part of the luck thing is whether or not you can find any thermal lift more than anything else. Assuming that none of us can see the lift with a naked eye and go straight to it, we are all at the same element of chance there. I would consider it the same kind of luck you would need to intentionally run into another airplane.

Jack
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Old May 09, 2012, 01:14 PM
Jack
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Thanks for sharing that, Viking.

I have not flown glider a lot yet and never in party with other gliders. And I would love to sample the flying in the wide open spaces of the west and high desert environments too.

I doubt that I'll ever sort out the details on ALES but in the meantime it is always in the back of my mind when I fly. Trying to arrive at one specific small spot and arriving there to the second is nothing I consider to be easy.

If you want to get a feel for the kinds of scores people are getting you can look at the results of ALES events in the ALES thread. This recent event would be a good example for just reading up on a typical event:

SVSS Monthly ALES Contest - Saturday April 7th - http://www.rcgroups.com/forums/showthread.php?t=1622621

The scoring is not described there but it is simple enough. You get 1000 points for landing exactly on the 10 minute mark and, depending on how close to the marked spot you are, you can also get a landing bonus. That would produce a score of 1000 or better.

If you land over the 10 minute mark points are deducted for how late you were and you get less than 1000 points. And maybe no landing bonus is available to late lander? I don't know all the rules...

Jack
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Old May 19, 2012, 05:28 PM
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United States, NC, New Bern
Joined Feb 2012
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The best KFm wing??

I got really disappointed way back when this thread turned into a Who thinks they are smarter than you contest, and LE shape got to be a major issue.(yes I do understand the issue). I am a regular Joe trying to build a fun, relatively inexpensive plane with limited skills but understand folding some foam will give a half way decent LE, if care is taken.
So I would like to know which KF wing configuration is the best to build for a 52" Blu Baby(just a trainer). Thanks for your input, Jerry 42
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Old May 19, 2012, 08:46 PM
Build straight - Fly twisty
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Australia, QLD, Little Mountain
Joined Feb 2010
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Quote: I got really disappointed way back when this thread turned into a Who thinks they are smarter than you contest

I agree, It's a bit rough when people start talking Advanced Theory and Science on an Advanced Theory/Science thread.
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Old May 19, 2012, 08:54 PM
treefinder
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SE MI
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KFM3 is a nice flying, strong yet flexible wing for the larger BB's
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Old May 20, 2012, 07:23 AM
Jack
USA, ME, Ellsworth
Joined May 2008
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springer probably has it right, the ** Kline-Fogleman (KFm) Airfoils - Building/Flying Discussion ** thread might be a better place for a discussion about building and flying a KFm wing.

As to the question, I think the best leading edge for quick and easy building is the factory folded edge on two sheets of FFF. And the KFm3P with polyhedral tips is awfully hard to beat in the wider spans.

Build that with a couple of 36" to 48" round dowels (1/8" in the leading edge fold and 1/4" in front of the 75% strip where the 50% strip overlaps it and you have a flat 48" wing that is hard to beat for flyability.

Want to make it a better trainer wing? Make a cut 8" in from each tip and bend up about about 2-1/4" to make a 15 degree polyhedral tip and you have what might be the strongest and best flying KFm3 variant for a trainer. Here is the details on a 48" KFm2 build:

http://www.rcgroups.com/forums/showp...6&postcount=36

I like the single sheet full width build on that, getting it out another two inches on each tip for a 52" span would require the tips be made separately. A 10" chord on a 52" wing would give your 520 sq. in. of wing area, if you wanted to get that in the 48" span you could make the chord to 11" and that would give you a 528 sq. in wing. The small change in aspect ratio to better suit the 48" FFF material width would not make for much if any difference they way it flies.

So that's my recommendation, a 48" KFm3P. You can see a 48" KFm2P fly in this post on the KFoenix Stick build:

http://www.rcgroups.com/forums/showp...3&postcount=43

And if you add ailerons to a KFm2P or KFm3P you can have a plane that has the incredibly wonderful flying talents of Russ40's Trainer Type Plane seen here:

http://www.rcgroups.com/forums/showthread.php?t=1281056

Jack
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Old May 20, 2012, 10:23 AM
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RE: the best KF wing

Thank you Springer, and jackerbes. The info is exactly what I was searching for.
I apologize for inserting into the wrong thread and will respectfully go to the "building and flying" thread with any further questions.
Thanks again for the help, Jerry42
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Old Jul 06, 2012, 10:32 AM
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Joined Nov 2007
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Hi guys!

I've been using gorilla glue to lamlinate EPP foam layers together to make the KF airfoils.

GG is sure hard to spread in a very thin layer.

Does anybody know of something I can use to THIN it before application, and that won't hurt the EPP foam?

I like GG because it seems that when it "foams up", it penetrates the cells and pores of the foam and really locks it together. Is there an ALTERNATIVE glue that also does this but is more easily spread?

Thanks!
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Old Jul 06, 2012, 01:28 PM
just Some Useless Geek
Chicagoland
Joined Oct 2008
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Well, I use various forms of spray glues like the 3M products. 45 is very easy to use and doesn't attack the foam with any gusto at all, but also doesn't adhere with the same vigor as 77 or 90. However, with the higher number adhesives you have the problem of the spray transport attacking the foam, so you have to be careful in applying it in real thin layers. Experiment a little and you'll get the hang of it.

Also, I have found that a fine mist of denatured alcohol makes the spray glues momentarily soft so that you can position parts before they are locked down. I use a spray bottle with an atomizer to get as fine a spray as possible. That way I use the absolute minimum of alcohol to get the glue tacky before final assembly.
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