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wing loading vs. preformance ???

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wing loading vs. preformance ???

Old 09-29-2006, 06:51 PM
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kamakasi
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Default wing loading vs. preformance ???

please help me with this. our local airport has deemed it nessisary to fence the whole lot in. while this does not hurt the power flyer it is really playing hell with the hi-start and winch lines. not being able to find a second sight to fly from i am forced to go to an e-plane. this in and to itself is not an issue what i can't get my head around is a really wild set of wing loadings. plane (1) is a thermik xl 4m. electric version comes in at 110 oz. aup. about 12 oz. per foot. plane (2) a thermik xl 5m electric version comes in at 214 oz. aup. about 21 oz. per foot. both plane share the same airfoil mh-32. my question is" can the mh-32 provide good lift at the 21 oz. wing loading. i admitt i like big but i can't seem to justify the weight penalty between the 4m to the 5m. remember this is mainly a thermal and xc ship.
Old 09-30-2006, 03:58 AM
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slopemeno
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Default RE: wing loading vs. preformance ???

I bet at 5 meters 21 oz to the sq/ft will seem too light. I did the calculation on my 3.7 meter DG800 and its wing loading was close to my 60" Higgins plane (a total lead-slead) and the DG800 seems feather light in the air.

How high a fence are we talking, BTW? Hope the flaps go down 90 degrees or close to it.
Old 10-01-2006, 10:35 PM
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Default RE: wing loading vs. preformance ???

The 4m at 12 oz/sqft will likely be a real floater that can kick out when needed thanks to the airfoil. Scale effect and reynolds numbers you know.

The 5m at 21 oz will likely soar just fine but even at that size and with that airfoil I don't think it'll fit in the floater class.


Those are sure some hella big options for models....
Old 10-02-2006, 01:34 AM
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rogerflies
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Default RE: wing loading vs. preformance ???

I built a 42% Spacewalker which had a wing loading of only 19 oz/sf. (135" span, 24" chord, 22 sf area, and 25 pounds) It worked quite well as a motorglider, and I routinely shut the engine off, worked thermals with it, and made precision dead-stick landings. I suspect the thermal performance would have been a lot better without the drag from the cockpit, windscreen, fixed 22" prop, and landing gear with bare 6"x1" wheels. The two-foot chord and tail-brace wires didn't help much, either.

I'd expect a clean ship that size at 21 oz/sf to do pretty well, but I don't think it will be a floater.

Roger
Old 10-06-2006, 03:26 PM
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Default RE: wing loading vs. preformance ???

I'm not taking the time to research your gliders but a non powered, true glider, should be in the 5-8oz/sqft. The arf bird of time is a heavy glider and it has 8.2 loading. Cheap 2M gliders run under 8. Motorized and if you still want thermaling you still want the loading to be as light as possible, I would want no more than 9-10oz/sqft. 12 seems heavy to me, 21 I wouldn't even consider to be a glider. As an example my Giant Aeromaster biplane has better loading and it's one of the highest loaded airplanes I have out of a dozen gliders (some powered), 3D(like my U-Can-Do @17oz/sqft), gassers(the Aeromaster and my big Quaker, my avitar, that has 5.4oz/sqft), competition fun flys (real good loading) and a few scale jobs.

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