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How to use rubber bands on avistar.

Old 07-05-2016, 11:34 AM
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krokodyl
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Default How to use rubber bands on avistar.

I rescently got the avistar elite, and am wondering if the bolts that attach the wings are safe. I am learning, so I will have hard landings. Everytime it hits hard, the wood that the bolts go through weakens, so it will eventually crack.

I think I will use bolts, and alsorubber bands. However, to use rubber bands I will need to have 4 of those wooden things. That would require me to drill 4 holes, and every hole weakens the fuselage. My question is, can I use the rubber bands without the 4 little things? Can I attach the bands somewhere else? It is only a backup, so it doesn't have to be extremly strong.
Old 07-05-2016, 12:33 PM
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JohnBuckner
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Those wooden things are called dowels and yes often used for wing rubber hold downs. Yes they are installed by drilling four holes and the dowels are positioned with a few drips of thin CA.

OK now you are severely over thinking this, there is no need for both a banded and bolted wing that is just needless overkill. If you are hitting hard enough to cause damage with either system then using both will just cause more severe damage when you do.


Man you need a mentor , yes the evil instructor who is likely to help see you through to success. attempting to be self taught is highly overrated and the so called 'right stuff' is just Hollywood fantasy.

The only other way to secure the rubber without drilling holes in the fuselage is to just glue the dowels across the bottom of the fuselage and use longer or doubled up rubber. 'But' all this does is make more aerodynamic drag and the airplane flies not so nice anymore.

John
Old 07-05-2016, 12:50 PM
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krokodyl
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Alright, I guess I wil just keep it the way it is.

And I do have a instructor, but he has to let me land and can't save every hard landing.

The only reason that I felt unsafe is bdcause I rescently crashed a different plane because the wing fell off in the air...
Old 07-05-2016, 04:42 PM
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John is correct. You are overthinking this. And he is also spot on about using both systems at the same time. Just leave it as designed. And crashing is part of flying. Learning to repair is also part of flying. Its why I am a huge believer in building your models. At least a few of them.

Now that you have a trainer start on a kit. I bet you will enjoy the experience. It may not have as fancy of a covering job or be as light as a cad designed ARF but it will be yours and no other will look like it. Sig makes really well designed kits that anyone can build if they can follow simple instructions. A good second plane is the Mid-Star 40.
Old 07-06-2016, 05:03 AM
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krokodyl
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Ok, thanks for the replies. Just wanted to know how reliable the bolts are.

I am going to start a kit soon. A few years ago I built a guilows kit. It was far from perfect, but lots of fun, and still looked good. Then I messed it up with the covering...
Old 07-06-2016, 06:38 AM
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JohnBuckner
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Hey don,t feel to bad about that first one. A common experience among many of us with our first stick an tissue ships, especially when we got to the covering part

Bolted wings are quite reliable and generally not to worry about especially with most modern ARF's but of course anything can be muffed up by the end user. Actually when a bolted wing separates in crash or hard hit that is considered a good thing since that will minimize hopefully even worse damage. That after all is the main idea behind behind the banded wings also.

There was a time that the earlier designed for RC airplanes in the Fifties often had main landing gear on swivel points and held in position with rubber bands so they would give way easily. And often the banded wings would include instead of a cross dowel at the front there would be fore and aft dowels so wing could slide off the fuselage easily in a sudden stop.

John
Old 07-06-2016, 04:11 PM
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flyboy2610
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I was taught that when using rubber bands, use two going diagonally across the wing, two each way, then use one fore and aft on the right and one for and aft on the left. I don't know if there's an absolutely "right" way to do it, but that's what I was taught.
Old 07-07-2016, 07:35 PM
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Originally Posted by krokodyl View Post
I rescently got the avistar elite, and am wondering if the bolts that attach the wings are safe. I am learning, so I will have hard landings. Everytime it hits hard, the wood that the bolts go through weakens, so it will eventually crack.

I think I will use bolts, and alsorubber bands. However, to use rubber bands I will need to have 4 of those wooden things. That would require me to drill 4 holes, and every hole weakens the fuselage. My question is, can I use the rubber bands without the 4 little things? Can I attach the bands somewhere else? It is only a backup, so it doesn't have to be extremly strong.
You'll have no problems with the bolts. I have an Avistar Elite and regularly fly very hard aerobatics with it stressing the wing bolts (its a play toy and to use for intro flights). I was recently farting around in 17 -22 mph winds (60 deg crosswind at that) at around 4', full flaps and just above stall speed. I got bit screwing around when a gust caught it rotated it into the wind and then the gust stopped. It instantly stalled dropped to the left wing hitting there first, then the nose. The wing bolts worked exactly as they should have and sheared off flush with the bottom of the wing. Because I had flaps down it also busted up the front retaining tab when one flap caught on the fuselage preventing the wing from pivoting off, otherwise there would have been no wing damage. The wing hold-down block is didn't split on mine. The only other damage was the firewall breaking loose and teh removable hatch busting up hit who knows what. Overall not bad on the damage as it could have been a lot worse.

Here's a video of a Top Flite 81" Cessna C-182 that I had to deadstick to show you the winds the Avistar can easily handle - this was just before I dumped my Avistart.

If you're having problems with the block, here's a way to strengthen it (this may be overkill for your mechanical experience level, but somebody not familiar with model repair may need this level, or more detailed instructions):

1) Bolt the wing on and put tape reference marks where it aligns to the fuselage so it can be properly realigned later on.

2) Drill the holes out and fit a dowel the same diameter as the drilled holes thus eliminating the holes.

3) Cut some 1/8" and 3/16" plywood the size of the hold down plate. Make sure you use quality plywood from the hobby shop made for model airplane use, not Home Depot/Lowes quality or light ply.

4) Clamp the lower ply doubler to the bottom of the plate and cut the dowel's to fit flush with the top of the plate (they'll be the same thickness of the factory hold-down plate).

5) Epoxy the plates and dowels onto/into the hold down plate. Use 30 min or preferably 60 minute epoxy for this step to give the epoxy time to soak into the wood. Also use small clamps (spring type closepins work good for this) to hold everything in place, and let it sit overnight to cure.

6) Once every thing has cured overnight, put the wing back on using the reference marks you made to align it. Then use a small drill (1/16" works good) and drill a hole directly in the center of the existing bolt holes in the wing. Step up until you reach the diameter to tap the wood for the bolts. Make sure you drill perpendicular to the top of the wing (normal to the wing surface where the bolt heads will sit - look at it bolted up when you make your alignment marks to see how the heads sit on the wing).

7) After everything is done, saturate the top of plate around the bolt holes with thin CA and let sit over night. This will harden the holes and threads. Then retap the holes and run the bolts in. I doubt you'll have any more issues with the hold down plates.

Modifying the plane for rubber bands is not necessary on this plane as it you will gain nothing and possibly weaken the structure. It will also require a bit of work to try and do with the removable front hatch.

Hogflyer

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