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Old Nov 12, 2002, 07:42 PM
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Richmond, VA
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What is the technique to attach packing tape?

I'm putting together a mini-flash and was wondering how you attach the packing tape as hinges. I've never used packing tape before and a couple of questions come to mind.

Do you leave a gap between the stabilizer and elevator or butt them against one another?

Do you put the tape on one side only so they can't be seen?

If the tape is on the bottom of the elevator is it difficult to make the elevator go up? It seems the tape would restrict the movement.

I know these are basic questions but not having done it before I don't want to screw it up. I'm sure that tape won't come off my nice Solite covering!

thanks,
Grant
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Old Nov 12, 2002, 08:10 PM
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North GA, USA
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I don't have any experience with the plane you're talking about, but I might be able to answer some of your q's.

Generally, you don't want to leave any more space than necessary between the control surface and body. Just be sure the control surface can still move freely without binding.

Some models use tape on only one side, others tape both sides. Two-sided taping should add some strength to the hinge, and as a consequence will add some resistance to movement.

Generally, the tape follows the contour of the surface rather than spanning the gap. In this way, resistance to movement is minimized.

Good luck. Be sure and post some pics once you get it finished!

Wings
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Old Nov 12, 2002, 08:52 PM
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thanks Wings, I'll give it a go!

I'll definitely post some photos as I think this pup is actually going to look pretty good!
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Old Nov 12, 2002, 09:28 PM
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Also, if you tape only the top or one side of the surfaces, then the sticky side of the tape is left exposed in the gap area. This will attract all manner of debris, grass, and grit, which will not only be unsightly but can cause a malfunction. Whenever possible, I always tape both sides. -thumbs
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Old Nov 12, 2002, 09:51 PM
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That brings up another question. Do you tape the entire span of the gap horizontally or just place two or three vertical strips.

I bought some ARF's before that had what looked like scotch tape that ran the span of the gap.

thanks

Grant
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Old Nov 13, 2002, 12:53 AM
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Entire span in most cases. The hinge will be stronger and more solid, not to mention you'll do away with any airfoil problems from air leaks and thus improve control and performance somewhat (or so I've heard...not that I'm some expert on the matter).

I wouldn't use Scotch tape unless the manufacturer recommended it. Generally, I would expect them to recommend either 2-inch, clear packing tape or a special hinge tape of some sort.

Lookin' forward to the pics!

Wings
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Old Nov 13, 2002, 01:05 AM
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Grant, I generally try to tape a control surface to within about 1/4"-1/2" of the full length. On slowflyers like the TM, this isn't really necessary, but faster planes usually benefit from a full-length taped surface. If this isn't possible or practical, depending on the plane, tape near both ends and once or twice between them, and also near control horns. Just be sure they won't flex or warp under load. Hope this helps!-thumbs
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Old Nov 13, 2002, 10:40 AM
Balsa Flies Better!
Stamford, CT
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Whoa...

Umm, a couple of quickie points-

Let's start with the geometry- on most smaller airplanes- a simple geometry to use involves keeping the trailing edge of the wing square, but angling the leading edge of the aileron back so it forms a shape like this |\ . Thus, when the ailerons are deflected downwards at 45 degrees or so, there is no gap and the surfaces of the trailing edge of the wing and the aileron are flush. If you press this together tightly, and then tape with some mylar tape- (somewhat stretchy clear packing tape- although you want it reasonably thin- the stuff I use comes in a dispenser from 3M and I think they call it Crystal Clear Tape or some such- not the easiest to find.) you will wind up with surface that is lined up reasonably accurately, has no gap (gap= bad) and flexes easily. You want a surface on smaller airplanes to be pretty floppy- otherwise the servos may draw too much current. It's not that critical how close to the ends you get- just remember that gap is bad. Occasionally having an extra set of hands makes this job a lot easier.

Sam
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Old Nov 13, 2002, 11:12 AM
All under control, Grommit!
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To add to what Sam has said, if you are using the clear tape for hinging it is important that you deflect the control surface downwards when you apply the tape. If you apply the tape with the surface at neutral then the tape will sometimes not allow the full downwards deflection to be achieved.

You can decide whether or not to add a second strip of tape underneath, pushed well into the hinge line which I have done on some foamies, but one strip on top generally works fine with small models. It is important not to leave a gap between the control surface and the trailing edge, lest you allow slop to enter the system where the tape can move without the control rods moving.

The clear hinge tape sold by Multiplex is very good and Tesa make a very similar crystal clear tape that does the job well. A newbie arrived at our field last week with the surfaces hinged with 3M "Magic" tape, the transluscent variety, stuck straight on the foam. That isn't really good enough IMHO, it's adhesion to foam isn't brilliant and it splits very easily along it's length if you get a nick. I replaced the hinges with the Tesa tape before flying the model and they were surprised quite how easily the "Magic" tape came unstuck.

Brian
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Old Nov 13, 2002, 12:18 PM
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Sorry Grant.....

I didn't mean to imply that you should leave a gap between your control surfaces. In my mind, I was thinking of the inevitable "gap" that occurs when a surface that is taped on one side only is deflected opposite the tape, i.e. "up elevator", exposing the sticky underside. Yes, gap=bad, especially in communications! Sorry if my reply has caused you any problems with your Mini Flash, but it IS a Mountain Models kit, which virtually assures your success! -thumbs
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Old Nov 13, 2002, 01:01 PM
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Megacoup has the right idea. Chamfer the bottom of the surfaces (or one side of rudder) at about a 30-45 degree angle. The angle will depend on how much movement you will need for the surface.

For large surfaces like full span ailerons, I like to tack the surface in place with a few pieces of scotch tape. To do this, cut a 1" long section and fold over the last 1/8-1/4" so you have a tab that will make it easy to remove. Use 3-4 of these to hold the aileron in place. This also lets you check if your joint is flexible enough. Now start with the packing tape (it helps if you can weigh down the plane so it is stable). Cut the tape to length and hold it over the seam. Press it down on one end and smooth it along the joint, removing the tacking tape as you work.

Now if you want to tape the bottom too, fold the aileron up ontop of the wing, press it down so it forms a crease in the tape and the top of the trailing edge of the wing is in contact with the top leading edge of the aileron. Now place the bottom hinge tape over the aileron and wrap it around to the bottom of the wing. When you let the surface return to neutural, the tape should be following the entire contour of the bottom surface, ie it is stuck up in the chamfer.

I hope you can follow that. If I were better with a paint program it would be quite easy to explain. If you have any questions, let me know.
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Old Nov 13, 2002, 01:08 PM
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OK, here is a really, really bad drawing of the bottom tape.
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Old Nov 13, 2002, 01:20 PM
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Butte, MT
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I usually sand both the wing and control surface to make the angles (up to 45 degrees -- don't need to be super accurate here) -- see drawing below. On mine I use the Permenent 3M Crystal Clear Tape 3/4" stuff on both sides starting with the bottom strip. When placing the bottom strip you will need to move the control surface so you have a 'flat' surface to lay the tape onto (where you sanded). Once that this down then straighten the control surface and simple lay a length of tape flat along the top. Done! Yes, I usually have to hollor for another pair of hands to help in this process....

Whoops, I guess you can't display BMPs.... Sorry .
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Old Nov 13, 2002, 07:38 PM
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Richmond, VA
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OK, it sounds like everyone advocates hinging at least on the top of the aileron. I get that you flex the aileron down and apply the tape.

Sam,
Is this what you were trying to say? I didn't follow it very well.

Doug at Mountain Models suggest beveling the bottom of the aileron only. I guess to better butt the two pieces together and you wouldn't need to bevel the top if the tape is applied to the top since it would swing out the way.

As far as the gap goes, what gap? When you put tape over the two parts there is no gap at least if you put it on both sides.

Grant
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Old Nov 13, 2002, 08:16 PM
All under control, Grommit!
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Grant

The gap that folks are referring to is the gap that would be left if you were to tape the control surface to the trailing edge without the two being actually being in contact. If you do that, then the slack piece of tape between the two can flex without the control linkage moving, which causes slop in the system, imprecise control and potentially flutter on the control surface.

You should bevel the front edge of the control surface with a single bevel across the whole front face of the control surface, as in the diagram above, if you are top hinging. You only need a double bevel on the front edge of the control surface if you are using a centreline hinge. That's probably what Doug meant.

Brian
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