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Old Feb 12, 2012, 10:33 PM
just Some Useless Geek
Chicagoland
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[ahem]

Advanced Theory/Science, guys -- remember?
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Old Feb 12, 2012, 11:06 PM
Build straight - Fly twisty
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Australia, QLD, Little Mountain
Joined Feb 2010
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Scarce commodities around here recently. Be nice to get some though...
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Old Feb 13, 2012, 07:08 AM
Jack
USA, ME, Ellsworth
Joined May 2008
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Quote:
Originally Posted by Whiskers View Post
Ah yes! The Cone of Safe Return.
With even a half decent glider the cone is very flat, and the high-performance guys need spoilers etc. to stop it from being embarrassingly flat during landing.
So it is actually a truncated cone, right? Setting with the small end down, right?

They have some competitive sailplane events where landing close to a marked spot increases your score. They have developed a specialized landing technique for optimizing those landings, they call it the "doink landing" but it is basically an intentional crash landing. The doink landing technique is described as "..fly to the spot, stand the plane on it's nose, and spear the ground...".

They even have a rule that if the doink landing renders the plane incapable of flying, no score is given for the "landing."

The sailplane community is slow to recognize the creative efforts of others. If they don't look around and see one on their flight line or actually being flown by one of their beloved "experts" they deny the existence.

It I were to go on a sailplane forum and suggest that the doink landing was anything but an intentional crash they would be all over me. And if I were to mention that crash landings are a technique that was mastered many years ago, and are still ongoing in the powered flight community, it would send them into a rage.

If you want to see something really funny over on the sailplanes forum, go over there and say aloud that "a sailplane with a motor is still a sailplane" and they'll really get wound up!

Jack
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Old Feb 13, 2012, 07:19 AM
gpw
“There’s no place like Foam”
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United States, LA, New Orleans
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Flew competitive sailplane briefly ... was very expensive to be competitive , and not really much FUN , so went back to Sport sailplane flying lying in a chaise lounge with a tall iced tea... hunting for thermals ... Relaxing and FUN !!! ... Most any airfoil works for that ...

Motorized gliders = Electric thermals ...
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Old Feb 13, 2012, 09:05 AM
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United States, OH, Bradford
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Quote:
Originally Posted by jackerbes View Post
...They have some competitive sailplane events where landing close to a marked spot increases your score. They have developed a specialized landing technique for optimizing those landings, they call it the "doink landing" but it is basically an intentional crash landing. The doink landing technique is described as "..fly to the spot, stand the plane on it's nose, and spear the ground...".

They even have a rule that if the doink landing renders the plane incapable of flying, no score is given for the "landing."
It's called a "dork" landing, and "dork" is a deragatory term. However, spot landings are an integral part of modern sailplane competition. Which is one of the main reasons why I personally do not like and do not participate in R/C sailplane competitions, even though historically my designs have dominated sailplane competitions.

Quote:
The sailplane community is slow to recognize the creative efforts of others. If they don't look around and see one on their flight line or actually being flown by one of their beloved "experts" they deny the existence.
Absolutely not true, in fact quite the opposite is true.

Quote:
It I were to go on a sailplane forum and suggest that the doink landing was anything but an intentional crash they would be all over me.
There are some who are that way, and even will resort to character assassination attempts and ridiculous rationalizations to suppress any dissent (much like what I see going on in some other areas of discussion). I have been the victim of that myself, I've lobbied in favor of dropping the landing points and developing contest tasks that are actually related to soaring, Typically I get a whole bunch of extremely supportive private e-mails from a huge group of soaring enthusiasts who agree with me, while a few "landing Nazis" publically flame me, including resorting to attacking me as a person when they can't refute my logic (again, a lot like what I've seen in some other places). I finally gave up and left them to their landings. For a number of years now, Joe and I have catered to the sport soaring crowd, although our planes do get flown quite a bit in competiton.

The whole landing controversy came about because the planes evolved faster than the contest tasks. Just about anybody could get a very high score because the tasks were no longer challenging to the aircraft. The contests were coming out with a lot of tie scores. Rather than fix the problem with better tasks, they added things like precision endurance (points subtracted for how many seconds below OR above the target time) and the landing task as a way to break up the ties. The contests became less about soaring and more like Navy Carrier. However, "lawn darting" a delicate and expensive flying machine is still frowned upon, and yes, if any pieces come off or the plane is otherwise unflyable, the landing points do not count. A truly good competitor can consistently put the plane down within a couple inches of the target and a couple seconds of the target time, with a smooth touchdown. Still, it's not about soaring, it's about landing.

RC Hand-Launched Sailplanes used to be about soaring. We flew as long as we could, no precision times or landings, if we were flying at the end of a round we could continue flying up until we achieved a "max" (no penalties for going over the max time), just about how well we could read the air currents and keep our models in the air. Then the planes got better (and I have to admit, Joe and I had a hand in that), they found the tasks easier, and they started inserting things like precision endurance into the tasks to break up all the ties. Now it's all Discus Launch, ridiculous launch altitudes, the soaring-related tasks are no longer challenging enough, and the DLG class is just as bad as all the others.

So, Jack, it appears that you and I have actually found something that we both fully agree on!

Quote:
If you want to see something really funny over on the sailplanes forum, go over there and say aloud that "a sailplane with a motor is still a sailplane" and they'll really get wound up!

Jack
There were some initially who felt that way, but that attitude is fading rapidly. Our best selling kit sailplane is our 2-meter electric, and electrics in general are taking over most of the sailplane market. The latest craze is "ALES", which is Altitude Limited Electric Soaring". This uses a small electronic device that kills the motor at precisely 200 meters altitude, and they also have a 30 second time limit on motor run. There are no winches or other big, bulky, expensive equipment to set up and maintain, they just go out and fly. So far, the precise limits on launch altitude seem to help keep the focus more on soaring, and the guys coming into this from the (formerly ostracized by the purists) electric camp do not seem to be so indoctrinated or enamoured with the landing tasks. We'll see if it continues, but there is hope.

However, with electrics, including sport electrics, performance is if anything even more important, and even harder to come by, due to the weight and drag of the motor and its battery. A few percentage points in things like L/D or sink rate can be quite noticeable, and the use of the electric motor when in soaring mode is definitely a no-no, even for sport flying. The plane is expected to have the necessary efficiency all by itself, not get it from a battery. In sport flying, using the electric motor for a downwind "save" is definitely accepted for safety reasons, but it's considered a mark of defeat, in the same category as the "walk of shame". It means that the plane and the pilot could not get the job done, so they had to resort to the motor to bail them out.
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Old Feb 13, 2012, 10:09 AM
Jack
USA, ME, Ellsworth
Joined May 2008
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Don Stackhouse wrote:

"..It's called a "dork" landing, and "dork" is a deragatory term..."

There you go again., Your habit of opening a discussion by saying I am wrong about something is not contributing anything to the quality of the discussion here.

Dork refers more to a type of person than anything else:

http://dictionary.reference.com/browse/dork

But words often get used differently so I'm not trying to say you are wrong. Just explaining my use of a different word than you use. Here is a post that verifies the validity of the term "doink" if you think I am making it up:

http://www.rcgroups.com/forums/showp...1&postcount=17

You can say what you think if it differs, you can even say you don't agree with that, but you cannot say I am wrong. That is the thing that get's friendly "it is OK if we don't agree" discussions off to a bad start.

No one here is not smart enough to read two posts and see that there is a difference of opinion. But for you to approach it and present from the viewpoint that only you are right and all other opinions have to be pointed out as wrong is not contributing anything to what you have to say.

I don't spell derogatory the same way you do either...

Jack
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Old Feb 13, 2012, 10:24 AM
gpw
“There’s no place like Foam”
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Gentlemen, I think we should resolve this by saying “to each his own “ ...
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Old Feb 13, 2012, 10:49 AM
just Some Useless Geek
Chicagoland
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Please, let's get back to arguing over the science -- or lack thereof -- surrounding the KF. Sailplanes make me dizzy, and the further discussion of same causes my jaw to crack in yawning. Really.
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Old Feb 13, 2012, 10:49 AM
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Jack, you are looking for things to get upset about.

The fact is that the most common term for that type of landing within the sailplane community is "dork". It's a fact. No personal attack involved or intended. I have never intended to attack you, I have merely tried to correct errors of fact, wherever and whoever they came from. That has been my intent within the discussion where I first encountered you (where your recommendation of K-F airfoils to the original poster was incompatible with what that person was looking for in performance improvements in his models), as well as in this particular thread, which you dragged me into by attacking me behind my back.

The fact is that K-F airfoils have significant problems with L/D, and a problem with L/D has important implications in the design of models, including sport models. That's a statement of fact, and is not, and has never been, intended as a personal attack.
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Old Feb 13, 2012, 10:51 AM
RC beginner
New York
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like they say: opinions are like , everybodys got one. but seperate from those there is s real world. some are fotunate enough to discuss and learn about it. the "scientific method" is one tool to this end.

just my opinion.
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Old Feb 13, 2012, 11:00 AM
just Some Useless Geek
Chicagoland
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Then perhaps we need to further specify what our focus in this discussion should be: are we aiming at ultra-high-performance applications for the KF, or are we interested in finding out what qualities of the KF can be applied towards general sport flying, simplicity of construction, airworthiness, reliability, predictability, robustness, etc? Are we perhaps too narrowly focused on the drag issue to the detriment of the KF's other qualities?

Do we need to split the discussion Yet Again so as to get back to studying how the KF can benefit the R/C equivalent of GenAv?
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Old Feb 13, 2012, 11:06 AM
Jack
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My apologies for getting into this here. It will stop here.

Don,

Welcome to the list of people who's posts I will not ever see again. You are the only person there as of now...

You just don't get it, do you?

Jack
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Old Feb 13, 2012, 03:19 PM
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I designed the Blu-Guppy to prove that one could build a sailplane with a KFM airfoil that could thermal "reasonably" well. The Guppy has a 96" KFM3 wing, and can stay aloft indefinitely in moderate thermals. Light lift was good for a 3 minute flight. That's about it.

What I considered reasonable performance for the Blu-Guppy would not be in the least acceptable to a competition soaring pilot. That's OK, because the Blu-Guppy was never intended to compete. I hoped for a sailplane that was reasonably easy to build, and fun to fly. Based on feed back, I achieved that. Even the local vultures liked the Blu-Guppy (see attached photo).

The bottom photo is a 35 year old Multiplex Flamingo converted to electric power. The wing span, area, etc is a almost the same as the Blu-Guppy, but the Flamingo is considerably heavier. Given all that one would think the Blu-Guppy could stay up with the Flamingo, but such is not the case. Flown side by side the Flamingo would be up long after the Blu-Guppy had to land. Not bad for a 35 year old bird. A modern design of similar dimensions, would leave the Blu-Guppy in the dust.

This doesn't mean the Blu-Guppy is a bad design, nor does it mean the KFM3 is a bad airfoil. If you want to learn to fly sailplanes with a airplane that is cheap and easy to build and repair (beginners usually do that a lot), yet performs well enough to learn soar, then the Blu-Guppy is a good choice. So is Jack's OSG. If performance is your over riding criteria, then neither plane is worth considering. Different horses for different courses.

Roger
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Old Feb 13, 2012, 03:23 PM
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Jack, both you and Don have valid points. From what I read he wasn't attacking you. He was just trying to straighten out some things, and put forward his point of view. Please don't take offense.

Roger
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Old Feb 13, 2012, 04:27 PM
treefinder
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Yeah, c'mon Jack, cut the guy some slack. I actually appreciated Bob's discussion and bit of history on competition gliding as I never bothered to research it, other than wonder why they would slam that expensive piece of carbon fiber into the ground and get points for it....

So, back on topic, who's gonna build the first full scale foamie model wind tunnel????
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