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-   -   Ailerons not straight (http://www.rcuniverse.com/forum/aerodynamics-76/11241259-ailerons-not-straight.html)

markhamregular 09-26-2012 02:33 AM

Ailerons not straight
<div style="margin: 0in 0in 10pt">I just bought a GP Revolver 70. When installing the aileron servos, I noticed that the ailerons are not straight all along. One tip of the aileron is slightly up while the other tip is slightly down. Will that cause problems on the maiden flight, or what can I do to minimize any adverse problem before the first flight.</div><div style="margin: 0in 0in 10pt">Thanks,</div>

da Rock 09-26-2012 05:19 AM

RE: Ailerons not straight
While twisting out the warp and holding firm, hit the aileron with hot air from a heat gun. Hold the warp out and let it cool. You may have to do it a couple of times, and may have to hold more than the twist out.

There is a lot that can be done with model airplane ailerons. The twist you mention wanting to take out is sometimes put in by others. If the tips of both ailerons are up, your wing will have washout, something many modelers like to have. Since our ailerons are held firm by servos, rigging them "out of alignment" works for other purposes than rotation on the roll axis.

In answer to your question about your ailerons, it depends.

If both ailerons have the same twist, and have their tips displaced upward, there is a strong probability that your model won't cause you any problems at all. If one aileron differs from the other, there is a probablility your model will show some kind of aerodynamic imbalance. The probability differs with the amount of difference in the two ailerons.

The original design of most of our models very probably assumes both ailerons will be identically shaped and not twisted. However, the amount that shows up with quality ARFs is so slight that most new modelers won't even identify it, and it won't matter.

What you should do however, is make sure that neither wing panel is warped. Do that first before judging the ailerons.

da Rock 09-26-2012 06:05 AM

RE: Ailerons not straight
I just re-read your post and noticed it is unclear if one aileron is twisted or if "One tip of the [one] aileron is slightly up while the other [aileron's] tip is slightly down."

In any case, a model like the Revolver was probably designed with untwisted ailerons in mind. It's not usually emphasized but ARFs usually benefit greatly from our going over the entire covering job, shrinking every bit of film with an iron or gun. While doing that it's even more worthwhile to inspect the surfaces for warps and removing them as we go along. The covering of open surfaces usually provides a significant amount of the rigidity needed. ARF workers aren't really concerned with anything other than the wrinkles their boss would notice. And ARF mfg's often aren't concerned with warps they think most wouldn't notice.

Both ailerons should probably be straight. They most certainly shouldn't be different from one another, unless you want washout.

edsplane 09-26-2012 07:08 AM

RE: Ailerons not straight
The ailerons are meant to change the camber equally and opposite for the wing halves, so that your rolling moment is uniform. If the right aireron has a different rolling moment than the left, with probably some additional drag, your plane will not do a smooth roll and may get weird on you when you least expect it. My suggestion is that you get each aileron dead straight, even if you need to cut out and replace the twisted sections.

By all means, first try the heat remedy previously suggested. But, with a fast plane like the revolver, don't gamble on the twists cancelling themselves out. You probably won't be that lucky. Good luck.

markhamregular 09-26-2012 08:04 AM

RE: Ailerons not straight
I will take a second look at them and take pictures. Maybe it will help.
It's the first time for me and I have build about a dozen ARFs.

Thanks for replies. I appreciate them. Will get back at you.

da Rock 09-26-2012 10:48 AM

RE: Ailerons not straight
A picture from directly behind the model would give the most info. Right on the centerline is best, showing both wings equally. Move the camera up and down until you see as much wing above the TE as below it. Move side to side until you see the same amount of fuselage to the right of the rudder TE as to the left. The camera winds up in the same place your eyeball would be if you were looking for wing warps.

markhamregular 09-27-2012 04:28 PM

RE: Ailerons not straight
<div style="margin: 0in 0in 10pt">When the side of the wingtips are aligned flushed with the wings, the root sides of the ailerons are slightly up. It&rsquo;s the same on both wings.
Once I figure how to post pictures, I will include a couple.


markhamregular 09-27-2012 04:39 PM

RE: Ailerons not straight

da Rock 09-27-2012 06:01 PM

RE: Ailerons not straight
1 Attachment(s)
One of the best ways to post pictures is with the RCU code that puts the picture into your post in a thumbnail. You get to it by going 'advanced' or by clicking on the 'reply' option that's in the upper right of each post. That 'reply' route is how I got the pictures plugged into this post.

Clicking 'reply' opens a window that looks like the QuickReply one, but if you look just below where you type, you'll see a couple of options for uploading images or files. I clicked on the 'Click here to upload images and files!' That will open an application window that you use to browse through your pc to get the picture(s) you want in your post.

I just now ran down to the shop and took a couple of pictures of small planes to show what angle has the most information visible if you want to show off a plane's warps or misalligned surfaces. That wasn't the best studio for the purpose, and they're small planes, but it was the best I could do tonight.

If you look closely at what you can see of the wings, notice I made an attempt to show as much bottom as top. When you look from a spot directly behind both wings, showing both equally, with some practice you can see if both wings are equally aligned first off. You can see if there is washout. Warps show themselves. etc

da Rock 09-27-2012 06:19 PM

RE: Ailerons not straight


ORIGINAL: markhamregular

<div style=''margin: 0in 0in 10pt''>When the side of the wingtips are aligned flushed with the wings, the root sides of the ailerons are slightly up. It’s the same on both wings.
Once I figure how to post pictures, I will include a couple.


(BTW, I clicked on the "quote" button to get here and it offers the upload options under it's typing window.)

If you are saying that your aileron tips are straight with the centerline of the wing at the tips, but stick up as much as shown in the pictures, then you have a problem that really should be solved. If both sides are up at the roots, but straight at the tips, your wing has washin. It's not what you want on a wing, and especially a wing with a symmetrical airfoil.

I would try to iron out each aileron. You can tape the root end of each aileron solid to the wing's TE to make up for only having two hands. Then push and hold the TE of the aileron at the tip to twist out the warp. While holding that, heat the aileron on both sides and then let it cool while holding it straight. Will it work? It does sometimes. If you can easily twist out the warp with your hands, the wood in the aileron won't fight too hard and it's a good bet the ironing will work fine. If the wood is rigid and doesn't twist, forget about ironing and figure you got 2 choices. Get the mfg to replace the wing panels or send you straight ailerons. Or build new ones and replace the old yourself.

da Rock 09-27-2012 06:25 PM

RE: Ailerons not straight
Another option would be to strip the covering off those suckers and steam the wood. It could be less work than cutting the present hinges to install mfg supplied replacement ailerons. They'd need new slots cut and those slots would be into a wing with a TE stiffened by the CA hinges you just cut.

BTW, the amount of warp shown in your pictues is enough to have an effect on the low speed stability of that airplane. If the warp is: tip down/root up, the plane will have a stronger tendency to tip stall on landing. Not good.

I just noticed the wrinkles in the covering in your pictures. The covering on the ailerons is loose enough (when wrinkles like that show) the covering really hasn't influenced the aileron wood to warp at all. It's worth seeing if tight covering can hold the aileron wood straight. If the wood is somewhat flexible, the covering should not only hold it straight, but stiffen it as well. It's worth the effort.

markhamregular 09-30-2012 07:43 AM

RE: Ailerons not straight
<p class="MsoNormal" style="margin: 0in 0in 10pt"><font size="3"><font face="Calibri">Thanks you guys for all the great tips, but I am not very handy, so I do not want to mess with the ailerons and brake them. I have only been 100% satisfied with all Great Planes I&rsquo;ve bought. This wing is really bad, all wrinkled and warped. So I sent an e-mail to them and they immediately responded that they will replace the wing. A great company backs its product, and GP is no exception. I will continue to buy from them.</font></font>



jester_s1 09-30-2012 06:33 PM

RE: Ailerons not straight
That's great they are taking care of it, but this is a fairly simple skill that every modeler needs to have. Even if a plane is built right to start with, warps can develop and wrinkles certainly will develop with humidity and temperature swings. Correcting them isn't hard using the method outlined above.

markhamregular 10-01-2012 02:19 AM

RE: Ailerons not straight

Winkles are fine. All models have them, and they are easy to fix. Those 2 ailerons have serious curves. I don't think it's fair to buy a product and have to take off covering, heat something and all the other things you have to do with risking to brake it. Anf if you do brake it, the manufacturer would not take it back. I have bought about 12 ARFs so far, and none of hem came with such a defect. I even built a kit one time, but I don't think it's my job to fix defects for a product from a leader in the industry. I once had a Nitroplane, and trust me I had to fix a lot of defects and the plane was a mess. It took 4 months to get a new cowl. But, I paid $99 for a product that GP would have charged me $300. So I swallowed the pill, but I will not buy Nitro again. But I don'r expect serious warps from GP.

da Rock 10-01-2012 02:39 AM

RE: Ailerons not straight
It quite easy to fix or repair or correct almost every proplem or break possible with model airplanes. Really.

Repairing problems and breaks is a good skill to develop. If you got to keep the wing with the defective ailerons they would be excellent to practice on.

It is most assuredly true that noone who purchases an Almost Ready to Fly should receive one that is defective. But keep in mind that the quality of ARFs being sold today seems to have it's ups and downs. The fact that so many of us are willing to take really awful ARFs without complaint simply because the price was discounted seems to have encouraged the Chinese to try and ship lower and lower quality. It also looks like the present suppliers to US retailers have put some of those retailers out of business thanks to the quality of the products they shipped.

It really looks like it's a good time to know how to repair stuff for yourself, not just so you can fix the plane you break, but so you can keep from losing the money you spent buying cheaper stuff. And so you'll be in a better position when quality drops on the more expensive stuff.

markhamregular 10-01-2012 05:44 AM

RE: Ailerons not straight

I agree 100% with you. I sure will practice with those wings once I receive the new ones.

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