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Old Mar 02, 2004, 04:03 PM
MEDIC!!!!!!!
roguewolf's Avatar
Near Fresno, California
Joined Sep 2002
1,741 Posts
New to slope, question about wingloading

Is there a relatively linear relationship between wing loading and wind speeds?

I expect that I will have to add ballast with increasing wind speed to aid in penetration and to keep from getting blown away.

I'm looking at 6.6 oz/sq ft on an EPP bluto-ish plane that I copied and expect it will be ok for light wind....how far off am I?

Thanks in advance,
Kevin
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Old Mar 02, 2004, 04:13 PM
Registered User
Long Beach
Joined Nov 2003
63 Posts
Kevin
There are so many different things that you have that goes into a ship that make it perform.Yes the right wing loading will get you close.Post some pics of your ship and let the boys here give you their input.There are alot of guys that I can see that they know what they are talking about.Good luck with the bird!


Later Glenn
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Old Mar 02, 2004, 04:32 PM
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Southern California
Joined Sep 2003
6,903 Posts
Hi Kevin--
I can tell you that it really depends on where you fly! I have a slope near my house that is GREAT for flying F3F and small light slopers as well as light foam planes--- these are all in the 8 to 14oz wing loading range-- but my favorite planes to fly are Semi Scale PSS Warbirds and I don't even bother flying them at less than a 14 to 25oz wing loading--- but most of my flying with them is at Pt Fermin and the Cajon Pass-- higher lift sites. For me-- anything around 10to 12 oz is a "floater" and above 25oz-- gets real fun real "fast"!!
Tim
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Old Mar 02, 2004, 08:59 PM
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surfimp's Avatar
United States, CA, Santa Barbara
Joined Feb 2003
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Drag is another big consideration as regards penetration. I've designed a small SPAD glider that has a very low wingloading, so it flies in relatively light lift (for something made out of Coroplast, anyways). Because all the gear is out in the wind, and because it uses a single surface Jedelsky-style airfoil, the drag is very high. This actually limits its light lift performance, because the L/D is not very good.

On the other hand, a Weasel has a comparative wingloading and far less drag (plus a real airfoil, not just a piece of kinked Coro ). It has a better L/D and will perform great in both lighter and stronger lift than the Coroplast plane. So it's more versatile, and if ballasted up the performance (in terms of energy retention and top speed) gets better.

To make a long story short, as I understand it the L/D performance of a given airframe remains constant regardless of the wingloading of said airframe. However, in order to achieve the best L/D performance, the ballasted airframe will have to fly faster. Which is what you want for stronger lift situations, of course...but a draggy airplane with ballast is still a draggy airplane, and while you may be able to wring some additional performance out of it via additional weight, for stronger lift conditions a sleeker, more streamlined plane will provide much greater satisfaction, especially when ballast is added!

Hopefully the experts can rectify any and all errors I've made in this explanation, but this is pretty much how things work as I understand it. But IANAE (I am not an engineer) so take my hackneyed explanation with a grain of salt

Steve
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