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Old Jun 22, 2011, 03:13 PM
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-=Brian812=-'s Avatar
USA, MI, Owosso
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Idea
tailless system??

Question for those serious engineers out there.

Seems everyone makes new styles of wings and pods but no new tails except pull and spring systems.

Has anyone tried a tailless system that pops out/up after launch?
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Old Jun 22, 2011, 04:25 PM
Father of Fr3aK, DLG Pilot
tom43004's Avatar
USA, OH, Worthington
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There are some flying wings around but I haven't seen anything "retractable" yet. Why don't you perfect it and share?
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Old Jun 22, 2011, 08:44 PM
usaf3kteam
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Quote:
Originally Posted by tom43004 View Post
There are some flying wings around but I haven't seen anything "retractable" yet. Why don't you perfect it and share?
Because it is not legal
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Old Jun 22, 2011, 09:05 PM
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-=Brian812=-'s Avatar
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Originally Posted by rcgeorge View Post
Because it is not legal
Change the rules??
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Old Jun 22, 2011, 09:21 PM
Father of Fr3aK, DLG Pilot
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Technically a retractable tail would be legal, provided you don't use it to launch
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Old Jun 22, 2011, 09:37 PM
Kyle Clayton
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United States, VA, Dinwiddie
Joined Feb 2008
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I'm not really sure that I understand the advantage of a retractable tail for launching? I thought the tails provide all of the wacky forces we need to keep these things from cartwheeling out of control and instead climb straight.
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Old Jun 22, 2011, 10:00 PM
usaf3kteam
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Quote:
Originally Posted by tom43004 View Post
Technically a retractable tail would be legal, provided you don't use it to launch
You could be right but it would be changed more than likely.
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Old Jun 22, 2011, 10:51 PM
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Where would it retract anyway... I don't see a need for this, am I missing something? Keep it simple, make it thin and throw it hard.
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Old Jun 23, 2011, 04:57 AM
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MGeo's Avatar
New York
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Quote:
Originally Posted by tom43004 View Post
Technically a retractable tail would be legal, provided you don't use it to launch
Out of ignorance, where does one find the official rules?
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Old Jun 23, 2011, 05:01 AM
Is my CG correct?
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Wollongong, Aus
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The more I hang around here the more it seems that anyone and everyone who flies DLG are purely comp driven? Just seems a lot more comp driven than any other style of flying I've seen.

I'm suspecting he is referring to a tail that is long for launch (longer moment and all that, you guys know better than I anyway), then retracts to normal length for normal flight
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Old Jun 23, 2011, 05:23 AM
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tailless ?????

Christian Behrens' Nurflügel DLG (1 min 15 sec)
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Old Jun 23, 2011, 06:16 AM
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ftp://www.fai.org/sporting_code/sc4/...soaring_09.pdf

DLGs fall under "F3K" in the fai rules.

Yes, it's largely competition driven, but that is changing. Our club has 8-10 DLG fliers and only two of us fly contests.
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Old Jun 23, 2011, 10:04 AM
Oleg Golovidov
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Raleigh, NC, USA
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The link Tom provided is for the 2009 rules.
Here is the latest stuff: http://www.fai.org/aeromodelling/documents/sc4
More specifically: http://www.fai.org/aeromodelling/sys...g_11_rev_1.pdf
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Old Jun 23, 2011, 10:47 AM
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Reno Nevada
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Quote:
Originally Posted by MGeo View Post
Out of ignorance, where does one find the official rules?
Having read the rules, there is no issue with having any sort of retractable tail. Basically, one can interpret the rules to permit any sort of geometry variation provided that the 1500 mm wingpan is not exceeded in any fully extended orientation and the radius of the nose meet the measurements.

The peg definition is poorly written, and can mean a few things depending on the outlook. However, the basic understanding is that the peg must be stiff, and within the halfspan and not extenable or retractable. We take it that the peg is glued orthgonal in some fashion to the wing and does not move.

The latter items, not extenable or retractable, really means that you cannot pull out the peg on some sort of support that moves the location of the peg further from the center of the plane, and effectively gives it a greater wingspan. If you read further, the peg must be stiff. All our pegs are stiff, but if you include the idea of holes, then you could still fold the peg into the wing surface. The extendable or retractable can have a second meaning, depending on the interpretation, that it cannot fold into the wing. But this is how it is interpreted now, but until a challenge is made, you could place the peg 1.5 inches inboard of the tip and then have it fold flush during flying. One could think that a hole could behave in the same way, because after release, the hole could be filled with some sort of foam or other surface that brings the wingtip into a cleaner flying mode. This has the same effect as a folding peg. You can say the folding peg is rigid to the wing, because it is. Its pivot point is rigidly mounted, doesn;t move on the wing (wrt location) and the peg's angle can be changed. As long as it does not affect the wingspan, you coudl do it. That would be the equivalent of retracting a tail in any way. It certainly is equivalent to adding or removing flaps, since they significantly change the projected wing area, as we measure planes, especially in the fully flapped landing mode.

However, until someone makes a retractable tail, or a folding peg, and it significantly gives the pilot a really distinct advantge, little will be gained by anyone filing a protest, or a rule change.

That's the way I interpret it.
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Old Jun 23, 2011, 11:49 AM
G_T
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Joined Apr 2009
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Quote:
Originally Posted by discostu956 View Post
The more I hang around here the more it seems that anyone and everyone who flies DLG are purely comp driven? Just seems a lot more comp driven than any other style of flying I've seen. ... flight
Most people do not build their own planes; they purchase them. Most plane manufacturers of DLGs make primarily or exclusively contest ships. The market is not as large for other types. Additionally, most manufacturers are actually competitive pilots and fly their own planes. So they make what they need, and the rest of us benefit from the ones they sell.

Sometimes I think that those that don't fly competitions possibly don't realize that it is a lot more fun to fly with a large group of your buddies. We call that a competition. But it has plane rules so that is what we fly. Most people at competitions are not competitive, and are merely there for the fun and comraderie.

In any event, modern DLGs perform amazingly well.

Gerald
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