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Oct 15, 2002, 04:23 PM
heli on the brain
dezflyer's Avatar
Thread OP

flying wing airfoils


...i recently took my passion for flying to the next level, purchasing a feathercut foam wing cutting machine. does anyone have any links or suggestions on the best slope/combat flying wing airfoils? any input would be greatly appreciated to help on saving wasted attempts. i just finished cutting one with a modified rg15 foil, test flight was good, but it seemed to be a bit slower than expected although very stable. whew! theres alot more to it than i had peviously thought! any feedback on achieving that balance of speed and stablity with the proper airfoil would be a tremedous help. thanx.
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Oct 15, 2002, 04:51 PM
Registered User
Here is a link for airfoils specifically for tailess aircraft:

www.b2streamlines.com/EH.html

Good luck with your project.

Found the correct site this time.

Terry Throop
Last edited by TThroop; Oct 15, 2002 at 04:54 PM.
Oct 15, 2002, 05:22 PM
No fuse too fat
slopeiron's Avatar
dezflyer,
Flying wings need a reflexed airfoil to be stable. The amount of reflex can be varied by the amount up or down in the elevons. You could probably even get away with using a symmetrical airfoil and reflexing the elevons but I haven't actually tried it.

As far as speed goes, a thicker airfoil will provide more lift and fly slower, while a thinner airfoil will provide less lift but fly faster. Lucky for us, in sloping you really don't need much of an airfoil. The lift is being provided by the wing area, not so much by the airfoil itself. This means you can get away with using a very thin, less draggy airfoil and have a plane that totally hauls.

Russ.
Oct 15, 2002, 07:27 PM
Slope Samurai Bushido
kbstingwing's Avatar

Best airfoil


You know the best airfoil is one you develope, I myself use only my own airfoils that I dream up, if you're not sure how to go about it, just imagine it in your head, and then draw it on a peice of paper, draw the root section first and then the tip section, then transfer the drawings to your template material, make sure to allow for wash out and dihedral if any, you can copy an airfoil but it doesn't make it yours, I've found more satisfaction and fun in designing my own and it's a proud moment when it works.
Heres an example of one of my prototypes, this is my skelton skyragers DRAGON; some of you might have seen this in another thread.
Oct 15, 2002, 07:40 PM
The MH series of airfoils were specially designer for flying wings. MH-45 and MH-61 seem to be really popular choices.

Eddie
Oct 16, 2002, 11:45 AM
Tu ne cede malis
MtnGoat's Avatar
Roger that on the Mh foils. I have not used the Mh6x's, but am beyond satisfied with the MH45 I've used on my latest two wings.

I've built flying wings with numerous different foils - S7003 (elevon trim provides reflex on that one), Tsagi 10, EH2/10, EH1.5/9, EH 3/12, and the RG15 modded with some reflex, and the MH45 outperforms all of them. Has a wide drag bucket, low minimum drag, and a great range of angles of attack with very high lift coefficient which makes for great turning characteristics with really sweet stall recovery. The S7003 and EH2/10 were my previous favs, with a nod to the S7003, which in in's normal non reflexed state is also great for standard planes.

My 72" delta with the MH45 is nearly always the last plane up in light air, even after the THL Zagi's and Red Herrings are down because it not enough, the delta is still dogging along with a couple clicks of up trim to put it in floater mode. A panel for this plane is 36" span, 23" root, 10" tip.

When the wind machine turns on and it's blowing like stink, a couple clicks of nose down and the thing is a rocket. I finished it in May, do a lot of flying and haven't needed ballast yet, no matter how windy it is, this foil has proved slippery enough to be completely configurable using trim for differing wind speeds. I'll be up with no ballast, passing all the ballasted wings my buddies fly.

Turns are gorgeous slow and tight if you want, it's very hard to stall it and if you do, just let go of the stick, count to 1, and you're flying again. Really fast recovery.

If I'm raving, it's because this foil impresses the heck out of me, I've never flown one with such a great combination of characteristics. The only difficulty with this foil is the relatively thin trailing edge which is hard to reproduce, I'm really not that close to a "true" MH45 because of that difficulty, my trailing edges are a bit shorter than they should be and this probably makes the performance worse than it should be, which is nuts because even as it is it flies better than anything else I've used. Don't let the thin TE scare you away, try it out, do the best you can on the TE, and you'll see what I'm ranting about! ---assuming you use a good planform!-----
Oct 16, 2002, 12:41 PM
No fuse too fat
slopeiron's Avatar
Quote:
Originally posted by MtnGoat
The only difficulty with this foil is the relatively thin trailing edge which is hard to reproduce, I'm really not that close to a "true" MH45 because of that difficulty, my trailing edges are a bit shorter than they should be and this probably makes the performance worse than it should be, which is nuts because even as it is it flies better than anything else I've used. Don't let the thin TE scare you away, try it out, do the best you can on the TE, and you'll see what I'm ranting about! ---assuming you use a good planform!-----
You bring up a good point. It doesn't matter what airfoil you plot out on your printer. By the time you make your templates, cut the cores, slice the leading and trailing edges off and glue wood in their place, then reshape the wood, chances are that the airfoil you end up with is not really that close to what you started out building. And therefore, any Reynolds numbers and other statistics are basically nothing more than a nice idea at that point. Who knows, by shaping the trailing edges shorter, you may have actually made the airfoil perform better!

Russ.
Oct 16, 2002, 01:02 PM
Your bird look anything like this, MtnGoat?
Oct 16, 2002, 01:04 PM
I'll try again .....

By the way, what kind of foam cutting setup do you have?

Eddie
Oct 16, 2002, 01:41 PM
Tu ne cede malis
MtnGoat's Avatar
damn, that's cool! yup, that's the baby. I've tried various delta shapes and that's still my best compromise IMO.

no matter what span, I wind up at those proportions again. More sweep rolls better, but you start to have stall and spanwise flow issues because of the proportionally smaller tips, plus the aspect ratio gets low and it doesn't hang as well.

Less sweep has turned out to be better for even more stall resistance in tight turns, and seems to float a better due to the higher aspect ratio, but it will not roll as quickly. So I always wind up back at the 17:12:5 ratio (single panel span: root: tip).

I use a triangular "bird" like vertical stab that trails behind the plane, I find it holds turns better than using a tall vertical stab like a picojet. That's my favorite thing about my latest bird, the planform/foil/tail combo holds a really nice turn. Set the bank desired, add a bit of up to start the turn, then let off and it just stays there.

It's all EPP cut from 4" sheets and weighs about 56 oz, yet with 9 square feet of wing the loading is still very low, hence the floatability.

For cutting I use a variac I got at a local electronics surplus outfit, with a handmade bow with a pulley and weight system for pulling it.
Oct 16, 2002, 02:07 PM
MtnGoat,

That looks neat .... so if I'd like a 48" version I would have a single panel turning out to be 24:17:7 based on your 17:12:5 ratio.

Got any pics of your creation?

Dezflyer .... have you used that Feathercut yet?

Eddie
Oct 16, 2002, 02:50 PM
heli on the brain
dezflyer's Avatar
Thread OP
...thanx for all the feedback guys, its a real help. is the MH45 the same airfoil that wedgie uses? i own a wedgie , and luv it, you are right, the trailing edge is pretty thin. im figuring that if i want to try to cut one with the MH45 it'll have to have quite less sweep than an electric powered one (wedgie). the only problem is that i just have the demo version of compufoil, which only has like 15 airfoils in it. before i shell out bucks for a airfoil program (ive seen some for $695!),are there any that are freeshare or can be downloaded for a little less cash? just was wondering, thought id ask. well, im off to pick up another load of epp, lets see what i can conjure up this time

...emoone... yep ive used the feathercut and am very satisified with its performance. a very cool tool indeed.

...re planforms; after getting an airfoil transfered to the template material, cutting it out, sanding it smooth, no matter which one that you pick its really going to be a modified version of that form anyhow. unless , of course, you're cutting them out with a cnc machine. but thats the whole beauty of it. pick a 'foil', cut n sand it, and its basically your own modified version of it.
Oct 16, 2002, 02:53 PM
Registered User

HS 2.0/8.0


hi All,

Anybody tried the HS 2.0/8.0 ?

http://www.aerodesign.de/english/pro...e_s.htm#hs2080

Looks good on paper. I am after something with the speed of a 56 bluto but the turn of a model with the JW foil

Ade
Oct 16, 2002, 03:18 PM
dezflyer,

Do a search for a program called "Profili" ... yes thats an "i" on the end ... its Italian but has English menus also. It comes with a ton of airfoils and has a fairly nice interface ... plus it is free!

Eddie
Oct 16, 2002, 04:55 PM
Tu ne cede malis
MtnGoat's Avatar
yes, the wedgie uses the MH45, you have a good example of it's speed range with that little bird.

Speaking of birds, and in keeping with the request for a photo, I have a neat shot of the 72" plane I've been talking about wingtip to wingtip with a hawk that paced me for a good 10 minutes last Sunday on our camping trip to a fav mountain in E Washington called Chumstick.

I do not have anywhere to post the picture for server access here, if one of you kind folks has a spot for it and can put it up on this thread for me, it would be very cool. my email is [email protected].


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