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United States, MA, Waltham
Joined Dec 2001
6,065 Posts
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I see 3 critical areas. How well does it launch? It seems like most competition gliders today launch very high in comparison to something like an old Mantis. Then there's strength to withstand the above, and to withstand dork landings.And then, how much does it weigh? I think the older gliders tend to be a little heavier than something like a Supra. I'm assuming the airfoil and wing design are reasonably good, but I suppose that's hard to know.
If it shares a lot in common with the Graphite 2, I expect that it's strong and launches very well. WIth the built up tips and tails, it may be lighter than my Graphite 2, which would remove the other issue. Mine has a lot of lead in the nose. Is this it? http://hotgliders.free.fr/gliders/hybrid_c.html Something to keep in mind: A v tail can handle very well if it's big enough, but a lot of them were made too small. http://www.charlesriverrc.org/articl...tailsizing.htm I don't know what the theoretical optimum is, but one might copy the vertical tail volume (cv aka vv) seen on the Supra: http://www.charlesriverrc.org/articl...upra_3view.pdf As long as the wing isn't too much heavier at the tips (i.e. larger radius of gyration) and the tail moment is a similar proportion to the span, this ought to work pretty well. Otherwise you might want it even larger. I have a Graphite 2 with a v-tail. It's kind of a handful when it's slow, and it has a violent stall which can be hard to recover from without losing quite a bit of altitude. Evaluated by the above method, it appears that the tail is something 40 percent smaller than it would take to be equivalent to a Supra. I think, since it launches so well, that a larger tail might make the Graphite 2 competitive. At least on breezy days. There's a guy in the ESL who wins with it now and then. Perhaps the same is true of your glider. I just did a back of the envelope calculation based on the drawing on that web site. I guesstimated the angle at 112 degrees. If this is so, and my numbers are right, the v tail is severely undersized for yaw. This could be fixed with a smaller angle and a bit more area, or by adding sub fin, or by enlarging the surfaces alone. However, I think the size is adequate for pitch, so enlarging the surfaces alone may be a bit less efficient. I'm thinking the sub fin would only have to have 40 square inches. Maybe I should do this with my Graphite II. Of course it's possible that little drawing is distorted and there's no problem. But I don't think so. My guess is that if those first 3 questions have good answers, and the v tail is larger than it looks or gets enlarged, it will be competitive. But really it's a piece of junk and you should send it to me so you don't have to bother disposing of it. ;-p |
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Latest blog entry: pics from Winthrop, MA indoor flying...
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United States, MA, Waltham
Joined Dec 2001
6,065 Posts
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Well, I can't go by my experience with the MH 32 as I think the tail on my glider is too small. However, I know people who like it. Rumor has it that you shouldn't slow it down too much. It must not be too bad, considering how popular it is. I seem to recall that Xfoil likes it. Certainly, on those occasions when I've gotten along with it, it's flown very well.
Anthony Procino flies a Graphite 2, which has the MH32, ended up in the top half of the ESL standings this year, even though he's a sportsman. (26 out of 73, better than me) Or was, perhaps he's been bumped up for next year. I dunno. Still, given a slightly larger tail, perhaps he'd have gained a few places. |
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Latest blog entry: pics from Winthrop, MA indoor flying...
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Joined Feb 2011
53 Posts
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Mike, found all I was talking about on 1 page - http://www.fvk.de/Englisch/Graphite-Standart.html
As you can see, there were 3 versions - all parts can be swapped. In fact the wings can be put on an Ava fuz. I would bet that other planes also use similar interchangeable parts. Hope it helps, Anthony. PS - the transparent yellow can easily vanish. Change to red transparent - at least it will look like a winner. (joke) |
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