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Feb 25, 2013, 03:32 PM
Director of Entropy
EarthMagnet's Avatar

Looking for airfoil advice for fast slope soaring wing

Hello all,

I know there are hundreds of pages of discussions on airfoils, but as I'm still relatively new I thought it would be easier to just ask.

I'd like to build a hand launch slope soaring tailless swept wing. Currently my only experience is with a Zagi THL, so I would like to stick with similar construction methods. Ideally I'd like it to be faster, slightly larger, and better for higher wind speeds (20-30mph). I'll probably hot wire cut the wing from EPP foam. I'm not so much concerned with durability and definitely not intending to do any combat.

I've looked over airfoil info here ( and it looks like a Sipkill or MH style airfoil might work for me? What do you suggest for such a plane?

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Feb 25, 2013, 04:15 PM
I bail out, anywhere, anytime
Taurus Flyer's Avatar
I suggest to ask this forum


Feb 25, 2013, 07:06 PM
B for Bruce
BMatthews's Avatar
EPP isn't the optimum choice for a faster flying design. It needs to be fairly thick to ensure the stiffness needed to avoid flutter. And it needs a spar to withstand the loads. It also doesn't have the best and smoothest surface finish.

To be able to use a thinner and more slippery airfoil you'll want to consider some alternative construction technique. Vacuum bagged glass cloth and epoxy resin would be optimum. But if you're not set up for bagging then polystyrene foam cores "sheeted" with glass fiber skins made up on sheets of glass isn't a bad option. The resulting wing panels would be pretty strong and definetly stiff enough. And it let's you get away with using thinner and more slippery airfoil options.

If you're keen on a fast sloper then you want to do more in terms of good design. The Zagi does a lot of things that are less than ideal in terms of how the control surfaces are tacked onto the rear of the wing panels. Control surfaces are part of the wing's airfoil shape. So when you're looking for low drag they need to be done right so that the airfoil can do what was intended.
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Feb 25, 2013, 07:35 PM
Director of Entropy
EarthMagnet's Avatar
Thanks Bruce. I'm up for trying a bagged wing or glass sheeted foam. I've been trying to find as much info as possible on flying wing designs, but I can't seem to find a basic explanation of planform options.

For instance, some of the larger ships have a thin wing cord and are shaped more like a V (see C09, whereas the Zagi and most of the EPP wings are chevrons. Are the thin chord wings best suited for thermaling and not sloping? Is there a generic name used for C09 type wings? What are the different flight characteristics of each style planform? Once I have that figured out I might be able to research my airfoil options more effectively.

If this belongs in a different forum please feel free to move it. I thought about posting in the Horton section but I'm not really looking to build a Horton (I don't think...)
Feb 26, 2013, 01:29 PM
Registered User
mhodgson's Avatar
Go for something like the CO5
Proven design, simple to build, should fly very well with the MH45 and have a wide speed range.
Most tailless models are sensitive in pitch and need careful placing of the cg but otherwise handle well.
Feb 27, 2013, 01:02 AM
auto-tune remix
slopemeno's Avatar
Actually, a stock Zagi 5C isn't bad, just add 10-16 ounces of ballast.

A friend of mine (Tick Point here on RCGroups) has used MH45 on a PSS Northrup Black Bullet, and it works great. It flies fast and is very stable.
Apr 23, 2013, 07:44 PM
Registered User
wildrooster321's Avatar
sd7003 will kick but however i suggest viewing the Nurfugal page and and leap whole heartily into the Hortons skip the Northrops inferior designs
that said more information would help like wing platform plank swept or tailless
a small taperd leading edge with a booom carbon arrow shaft and a small vertical can be made to rock your world but are you ready for such a beast

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