Airfoil choice for flying wing, help needed

[slowflyer]

Myself and a friend are thinking about cutting our own Zagi type wings. Any advice on the airfoil choice? Does anybody know what type of airfoil is used on the Zagi? Thanks--Rob

[Haldor]

I dont know the airfoil on the Zagi but the MH30ish airfoils where designed especially for flying wings and should be given a look.

If you have/locate Profili - a freeware airfoil plotter - it have the Zagi airfoil in its database.

Happy flying!

[fisher]

I’ll probably get some flak for posting this ,so I’ll put on my flak jacket first.
I don’t like cambered airfoils for tailless planes.
Zagi included.
I have a Zagi and it is a fun little plane. However it has some bad habits at certain angles of attack and certain speeds it is a squirrelly little monster. It will dip suddenly in ways not expected.
Other flying wings of my own designs which I used a “semi symmetrical” airfoil had the same or worse characteristics.
Cambered airfoils create a pitching moment which changes with the lift being generated. symmetrical Airfoils do not. I believe this is the problem. None of the symmetrical winged flying wings I have built had these problems.
-fish

[cwatters]

Try Martin's site for info on flying wings...
http://beadec1.ea.bs.dlr.de/Airfoils/nf_1.htm

Colin

[fisher]

Good link!
Answers a lot of the questions I've had
Thanks
-fish

[Dereck]

Slowflyer
All half dozen or so tailless I did - admittedly 'plank' wings with low AR - used symmetrical sections. Mostly NACA 0012 based, one 0015 based. All flew pretty much like a "conventional" would, though you had to be somewhat precise with touch down speeds - the short wheelbase UC mostly - and snaps / spins happened very fast. Otherwise, vice free and real fun to take flying.

My low winger also added field long knife edge to the envelope. That was a trip - it looked like a short conventional model from the side, in knife edge it caused some surprised looks at big events.

I did build one 'vintage' styled model with a Zagi-like wing planform. Only intended to loaf around slow and upright, it had basically a NACA 23012 with a little reflex built into the last 30% of the section. It was lost to a tiny problem (the elevons shifted on their sewn hinges, locked up and she dived into the ground http://www.ezonemag.com/disc/frown.gif) but was stable enough. I incorporated some washout into that one, but it didn't fly enough to really say if that was necessary or not.

Hope that helps

Dereck

[berniep1]

Hi Fish!

Well...you are going to have a pitching moment in a "conventional" plane too if you are using cambered airfoils....sure you can use symmetrical on everyting you fly but only if you are a "full-power-all-the-time-guy"...you just don't see many Sukhoi's or Cap's lazely circling in thermals.... http://www.ezonemag.com/disc/smile.gif http://www.ezonemag.com/disc/smile.gif

Bernie

[berniep1]

Back to the acutaly question: I would use a MH45 -- it's a good airfoil with pretty much a neutral Cm...and not to thinn (on foam wings that's important)

Bernie

[Jonas Leander]

A guess is that Zagis use either "Zagi 10" or "Zagi 12". Both are available in Profili.

I have myself used EH3012 to good effect.

/ Jonas

[maciek]

I spoke with someone from Trick-R/C; he might have been the designer of the Zagi. I asked him about the zagi10, zagi12 and the tsagi airfoils in the Profili program. He said that those might be the old airfoils. The new zagi has totally different airfoils and the root and tip airfoils are not the same. I want to build my own wing too, and I'm gonna go with MH45 and Martin Hepperle's design procedure.

[Jonas Leander]

Good point, maciek.

I know that the Zagi THL uses the Zagi 12, but this model is a few years old and obviously not designed for e-flight, being named THL. I would go with something thinner for e-versions.

/ Jonas

[dave_lilley]

Check out the foam EPP wings at FlyingFoam.com

[fisher]

Originally posted by berniep1:
Hi Fish!

Well...you are going to have a pitching moment in a "conventional" plane too if you are using cambered airfoils....sure you can use symmetrical on everyting you fly but only if you are a "full-power-all-the-time-guy"...you just don't see many Sukhoi's or Cap's lazely circling in thermals.... http://www.ezonemag.com/disc/smile.gif http://www.ezonemag.com/disc/smile.gif

Bernie

Yes Bernie they do; but they also have a considerable moment arm to the stabilizing surface which is not available on a flying wing.
I was not referring to thermal glider design. Perhaps I miss understood what slowflyer had in mind. I assumed he meant a electric powered or sloper. You see lots of symmetrical airfoils there.
-fish


[This message has been edited by fisher (edited 06-22-2001).]

[davecee]

Bruce Tharpe, designer of the Vortex (symmetrical airfoil ), replied to a question of mine on RCO. He said that reflex was not needed on a flying wing airfoil. Most flying wings are nose heavy in the interest of stability, which then requires added reflex of the airfoil. Moving the CG rearward incrementally as far as possible, without compromising stability will get you a flying wing with no need for reflex ( or a cambered airfoil ). This plane will not need to fly at full throttle all the time as mentioned by Bernie. The Vortex flys extremely nicely so set up, with a good speed range and very stable handling. Admittedly the allowable CG range on some planforms may be very small and it may be difficult to "get it right" Dave C.

[slowflyer]

Thanks for all the good info guys. I kind of copied the airfoil on the Zagi, but shortened the wingspan 4 inches. I had the wing cut from white foam. I'll let you know how it flies.---Rob