SS wing Dihedral, how much is too much? too little? - RC Groups
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Jun 10, 2003, 07:58 PM
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SS wing Dihedral, how much is too much? too little?

I built my slowstick to be a good beginner plane. I made it with this much angle in the wing. is this too much? it flies very well now, but I wonder if i'm sacrificing something here. what are the nuances of wing dihedral? lift, efficieny, stability? would I get more lift if I flatten out the wing a little more? will my plane crash because of it? would it make any difference or help anything? Thanks
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Jun 10, 2003, 11:34 PM
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wolfance's Avatar
Seems normal to me.

Jun 11, 2003, 12:49 AM
Smooth Air
Morb's Avatar
Looks good......that's what it should be at.........It is a slow flying plane, so the dihedral will keep it aloft at those slow speeds.

*sigh* I love my Slowstick.
Jun 11, 2003, 07:06 PM
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Andy W's Avatar
The way the kit is designed, you can't get it wrong..
Jun 11, 2003, 08:17 PM
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i don't think the designers intent is anywhere near that much ...... you must've bent the heck out of the kit supplied aluminum tubings to do that... the instructions and experience communicated to me to just match the folded wing's adjustable dihederal angle to the furnished tubings pre-set angle.. and not actually glue & tape the wings as far as they would fold out and upward to an obviously extreme angle and i guess you bent (and probably weakened) the tubings to match that ..... but what the hay.... mine isn't even 1/2 that much of angle and turns as tightly as i would probably need .... i'm having a ball trying to master inverted flight antics and perhaps knife edges where i don't know if an extreme dihereral angle like your photo would help or hurt compared to the prebent tubings angle or even a lesser dihederal.......but for whatever reason you did, let us know your results... if good, we may want to try also.......... kw
Jun 12, 2003, 12:19 AM
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the result is VERY stable and predictable slow flier. I folded the wings so that the centers met, if that makes sense, and the GWS kit that I got did not include the aluminum brackets, so I had to go to the LHS to get some aluminum tubing, so the bend is all me. It will flatten out very quickly from a hard turn which I love, and I just got brave enough to loop it tonight, and she loops like a dream, but trying to fly inverted is a bit like balancing a marble on a beach ball (to steal an anology from the "rules of flying a helicopter") My question is, will I get more lift with less dihedral?
Jun 12, 2003, 12:33 AM
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i'm not an aircraft expert, but if you kept increasing the dihederal angle until the wing's top surfaces touched directly over the fuse, you'd have an effective near zero lifting wingspan......... so, i would say that more dihederal angle reduces a given wing's lift and less angle gives the max available potential wing lift or so it seems to me....... kw
Jun 12, 2003, 12:26 PM
Registered User
If you consider the lift force as perpendicular to the plane of the wing, as you increase the dihedral, you will have a progressively larger portion of the lift force pushing horizontally, towards the plane fuselage, instead of vertically. That is the component responsible for giving lateral stability to your plane, but it is not contributing to lifting your plane at all. Hence, KillerWatt is essentially right - the more dihedral, the less lift.
Jun 14, 2003, 09:53 PM
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Originally posted by KillerWatt
i'm not an aircraft expert, but if you kept increasing the dihederal angle until the wing's top surfaces touched directly over the fuse, you'd have an effective near zero lifting wingspan.........
(tounge in cheek *on*) I decided to test that theory, and yes, it is true. If you increase the dihedral angle to the point where the wings touch, then indeed, you do have essentially ZERO lift. This point is demonstrated best when the plane is flying. (tounge in cheek *off*) Sigh. Yes, a mid-flight, (mid-loop) example of the more dihedral = less lift theory was put to the test today, and sadly, it is true. About 40 to 50 feet above ground, I pulled a hard loop from a dive and folded the wings. My slowstick hung in the air for a second, and I thought that it might still fly with the wings straight up like that (split second denial) and then it plummeted to the ground. Bent prop shaft, broken prop, broken gear box, bent rudder. I'm just going to buy a new SS and save myself the trouble of trying to repair this one. BTW, what are some GOOD strengthening mods for the wing? besides a brass wing connecter I mean....
Jun 14, 2003, 10:38 PM
Smooth Air
Morb's Avatar
Sand the centre part a bit till you see some white, then epoxy the two haves together. The sanding will allow the epoxy to bond better.

Then epoxy the carbon rods to the wing, instead of just taping them on. Some people have also put some carbon rods on top of the wing across. Haven't found a need.

You're right, I've done alot of pricing, and it is MUCH better just to buy a second Slowstick instead of ordering spare parts. You can still fix that wing though, by epoxy it back together, and taping it up.
Jun 15, 2003, 01:10 AM
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Not an expert, just a lucky guess...... nice of you to flight my "increased to 90 deg dihederal theory".....but seriously, i've got a new theory about the higher and faster you hold a terminal, sustained nose dive.... the deeper hole it makes.... any test pilots avail ?? ......... kw
Jun 17, 2003, 03:54 PM
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Less dihedral = more of a pain in the A$$!!!! put together a brand new SS and this time used brass for the wing connectors and used WAY less dihedral, almost stock I think. THE TURNS SUCK!!!!!! I'm so upset! when I kick the rudder out, the plane just starts to fly sideways for a while before dropping the wing to turn, then when it finally does, it goes way over and is difficult to control. I was happier with the amount of dihedral I had in the first picture. My rudder throws are maxed out, and I can't turn NEARLY as well as I could with more dihedral. AND THERE IS NOT REALLY ANY SIGNIFICANT LIFT GAIN!!!! PLUS, it handles like a dog in the wind. I think I'm going to increase the angle on this wing as LESS DIHEDRAL = LESS CONTROL.
Jun 18, 2003, 06:32 AM
29 rods from you in western WI
Karl Bē's Avatar
Keesercc -

I started out with brass tubing and bent them to match the wing mounts. After taping them to the wings, I noticed that the wing had a gap in the middle. I just taped over it (per instructions), and gradually over time and many flights they eventually bent up to almost the angle shown in your first picture.

I rebuilt my wing because the taped spars were moving under the tape. I reset the brass tubes to the original angle, glued the spars to the wings with polyurethane, and filled the gap in the middle of the wings with a wedge of balsa and more polyurethane. The wing is substantially flatter, probaby like your second wing. With one panel flat on the table, the other tip is 4-1/2" above the table.

What I've found (I'm a long-time pilot) is that the rate of banking, and therefore turning, is slower, and once banked and turning, it has more tendancy to keep turning. A bit of opposite rudder will straighten it out and level the wings. My rudder throw is around 30 degrees each way. The only way to do this is to drill a new hole on the rudder horn closer to the base.

While it's not as nimble and easy to fly, I'm using my SS for aerial photography, and find that the reduced banking gives more predictable pictures, less shots showing nothing but sky. There isn't a noticeable increase in lift, you're right. It is much stronger with the mods, though I still don't recommend power dives. Inverted flight was barely possible before, and is somewhat easier with the flatter wing.

Because the increased dihedral may tend to rock on the wing mounts, some people put small shims on the outer edges of the mounting brackets to better secure and steady the wing. In my first wing, I found that after putting plenty of rubber bands on, the dihedral flattened out a bit, yet would flex up again once airborne.

BTW, my SS weighs 19.5 oz with MiniAC brushless and 9x1100 Hecell pack, and tops out just over 22 oz. with digital camera.

Good luck,
Jun 19, 2003, 10:59 PM
Registered User
IN comparison to the pixs of extreme dihederal angle, my S Stick has a total 4.00 inches (about 10 degs) of dihederal angle which closely matches the kit supplied pre-bent tubings, flies great and can do a complete 180 deg turn within 1 wing span during speed at level flight...which i consider a tight turn..... i'm having no turn or banking problems whatsoever, you just have to fly it right...this is combined a tall trailing edge wing to fuse spacer resulting in about 2 deg NEG wing angle of attack, turning this slow flyer into a fantastic speedy aerobat capable of sustained circling and turning inverted flying with what amounts to wing anhederal....... i just don't see any turning or banking problems with a moderate dihederal angle and makes for a more capable and exiting flyer......... kw
Jun 19, 2003, 11:15 PM
Been There! Done That!
boomerace's Avatar
Carbon rods on top of the wing are not very effective as they need to be under the wing so they are under tension not compression as on top! That said the new wing I am building for the Monster Astro 020 SS wiill have a strip of 1" carbon tape epoxied to bottom of wing at CG full length of wing and another 1/2" strip full length at the TE! The wing dihedral joint will have brass tubes with 6" piece of heavy music wire CAed and wrapped as additional tube reinforcing! It is necessary as that brushless setup produices over 40oz of thrust and without the bullet proffing of the wing it will fold! (Ask me how I know!)
My MiniAC brushless SS since it isn't as heavy and does not produce the higher stresses has the wing cris-crossed on the underside with 3/4" packing tape along with a extra strip at the CG full length ala Zagi! Very little flex in the wing after taping! Have done power dives without much wing flex!

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