I hope I don't get a wise answer like, "If the kit comes with them, they're important." That may be. The reason I'm asking is because I know of a few people that have removed them from their Piper Cubs, with no ill effects.

Is is the long, slender wing of the cub (and Citabria, etc) that make the struts important to structural integrity?

I have a cub with a 76" WS, and I fiberglassed taped around the entire wing joint. The wing gets securely bolted down to the fuse.
How is this plane any different than any other plane, with just bolts, and no wing struts (or just rubberbands, for that matter?!)

The instructions that came with mu GP cub 40 state the the wing struts are purely for looks and not structural. most of our models are plenty strong without struts!

Thank you! My model is from the German company Graupner, and it doesn't state how important (or not) the struts are.

Nobody can answer that question since you did not state which Cub you have. Cubs are arguably the most modeled airplane in history and literally different kits in the hundreds and that goes back to the thirtys.

Now with that much variety in design of one aircraft you will find as much varience in stuctural design philosophy as there are designers. Such differances as I beam spars with or without shear webbing, Box spars, beam spars, single spars, two spars, sheeting to form a 'D' spar, aileron spars, solid ribs, built up ribs and the list goes on. Because of this differing design philosiphy of course some will require the lift struts and some won,t even with ships of similar sizes.

I only recently witnessed A wing fold on a large Taylorcraft simply because the purchaser of the aircraft forgot to put them on when they were a structurally required part of the airframe. While at the same time a Hanger Nine eighty incher has no problem at all.


John

As above, the cub is by Graupner http://www.rcuniverse.com/reviews.ph...ew&reviewid=20

I put the spar in, but I can't comment on its strength b/c I have nothing with which to compare it (this being my second plane ever). I'll email Graupner. Think of this: physically, my cub's wings are subject to no greater force than any other wing (and probably less than aerobatic planes, as this is a scale flyer). So, from a physics standpoint, is the cub's wing any more likely to fold than say a wing of similar dihedral, length, etc? The answer must be no.
I would guess that an aerobatic plane's wings would be under greater stress--most of them have no struts.
So it goes back to the strenght of the spar, the quality of the kit, and the fastidiousness of the builder.

Paul nothing could be further from the truth as that statement. To suggest that two different model designs should be of similar strength because they are of similar span, Dihedral and Shape is patently ridiculous and For the reasons I outlined above.

Your second post identifing the type Cub was not up when I posted. I have no familiarity with that ship and indeed I suggest you check before flying without struts. The fact remains there indeed are some model Cub designs that can be flown without the struts and there most certainly are some that cannot, You asked the question why in your first post and I did my best to explain. If you care not to accept that then thats fine
but I will not belabor the point any further.

John

[QUOTE]Originally posted by JohnBuckner
[B]Paul nothing could be further from the truth as that statement. To suggest that two different model designs should be of similar strength because they are of similar span, Dihedral and Shape is patently ridiculous and For the reasons I outlined above.

John, thanks for all your insight. I was not saying that two wings are always of equal strength (of course they are not--as you said, the spar as well as other factors contribute to its stength). I stated that airplane wings, all things being equal, are subject to the same stresses, wingloading, etc. A cub wing is under no greater stress physically than any other plane wing, given similar dihedral, etc.

I guess I'd have to ask, why fly a Cub without them? Or any other model of a full scale plane that had them.

If you don't want to fly a plane with struts, buy a plane that doesn't have them.

In my opinion, nothing looks worse than a "scale" airplane like the Cub flying without struts. (Well, maybe a jet with a prop on the nose, or most fun-fly plans, or profile planes, or.... )
Dennis-

I also have a GP40 cub. have to disagree with bearmech as the instructions that came with mine had in big bold print, a warning to Never fly without the struts installed as they are fully functional and NOT just for looks.
Jim

In general, the 40 size and smaller planes can get by with no struts. Most 1/4 scale size require them. It really depends (as mentioned above) on the design, you can most probably beef up any wing enough to not need struts if you are willing to carry the added weight. If they are necessary, the instructions usually say so.

I ask about the need for wing struts because it takes me pretty long to get them on and off. I have a small car, so the wing needs to come off each time. Please don't tell me I'm in the wrong hobby if I don't have the time. I'm a physician who saw 90 patients today, and I flew on my lunch hour behind the office during the only time I had to eat in a 12-hour day. It is just that every minute is precious.

Alright, I've got all your opinions. Thanks.

Pau

Paul,

Try leaving the struts attached to the wing, and just unscrewing them from the fuse. Less bolts to mess with, and a faster wing on and off. Or, if you need more play, loose the wing attachments enough to let the strut move, but don't take it all the way off.

You could always build yourself a new wing that is strong enough to take the loads with out the struts if you wanted to, or modify the existing wing to make it stronger, depending on it's current state, and how much effort you want to put in it.

Can you see inside the wing to see how big the spars are, how things are layed out, if there is shear webbing or sheeting on parts of the wing, etc? Maybe with more info, some of us might offer a guess as to wether the wing is strong enough to fly with out struts or not. What's the RTF weight?

Thanks for the suggestions, Kirk. I got an email back from Hobby Lobby, one of the US distributors for Graupner. Their feeling was that the struts are functional/important. I just received a second email where one of the guys at Hobby Lobby just saw the identical planes wings fold in flight (struts were off). There's the answer!! Again, Hobby Lobby comes through. They always impress me.

outlw36

How old is your Great Planes Cub? On page 38 in my instruction book it says"The wing struts arefor scale appearance only. Built according to plans and instructions, the airframe has sufficient strength for normal aerobatic flying without struts." Is your cub completed? have you flown it yet? Mines not quite complete. If the instructions are encrust I need to know before completion. Not trying to start anything (yea right lol) Just trying to help.

Thanks
Dwayne

paul c

are the wing attach fittings designed so they can be folded against the wing for transport like table legs? If not it should not be to difficult to design some brackets that would allow for this, then use pit pins or similar at the bottom attachment for quick set up! Darn I wish I had Minnflyers graphics capabilities!!

Bearmech, I bought my cub last fall. It is the 81' wing ARF. I don't have the manual handy right now or I would look on it for date info and page # etc. Will look it up later and let you know.been flying mine for about a month now . Flies great. Only flaw so far is the hinge material on the struts I have had to to repair 3 of the hinges so far as they start to seperate. Gonna try a differant hinge material if it continues. Mine is powered with a saito 65 with a 13x6 prop.

Jim

That must be the differance. Mine's the full kit, 40 size, 61" clipped and 76.5 standard span's. I clipped mine! I planed to build mine with struts any way, but if it has to be functional I might change the design from the plans.
thanks

The struts do fold against the wings, and I plan on replacing the nut and screw setup with cotter pins (I've already tried the pins on the ground---they do hold tight). I have small hands, and I still have a hard time using the screw and nut. Regarding my story above about a guys wing folding--what actually happened was that the screw holding the strut to the fuse fell out, and the wing folded on that side.