Re: Sharp pull up at bottom of loop with Avistar

One thing that immediately comes to mind is that you're flexing the elevator linkage at the bottom of the loop (where the airspeed is highest). The wing may be moving, as another poster suggested. Dr.1 Driver "There's a Hun in the sun!"

Thank you for the suggestions. I don't think it's the linkage as it's made of some pretty stiff wire, but I haven't flown all that many planes either. I'll try the extra rubber bands as a start and see if that helps.

~Dan

If you are not using fourteen #64 rubber bands to hold the wing on, then you know what the problem is now.

Ed Cregger

I don't remember where I heard the following rule, but I am using 1 #64 rubber band per pound of airplane, with the total being rounded up to 6 for my 5 lb plane. Was the 14 rubber bands a joke, or were you serious about that? I will up the number, but do you think it requires that many?

Along those lines, I was using my rubber bands for 2 flights and putting them in talcum powder to degrease them, but it was a mess (got powder over the plane), so I reverted to using them for only 1 flight. Is it worth the bother of storing them for another flight or does everyone normally just throw them away?

Thanks!

~Dan

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No, I am not joking.

The last thing that you need is for your wing to be moving around while you are flying. I arrived at fourteen rubber bands by trial and error many years ago. I'm sure that twelve would work, but why skimp? Rubber bands are cheap and model airplanes are not.

The chord of the wing, the weight of the model and other factors figure into it too, so use more if you need them. I wouldn't use less on anything forty powered and above.

No way is six or eight rubber bands enough for a forty powered model. I'd set aside the formula that you mentioned. No disrespect intended for the teacher of that rule. Time changes everything.

Back when I was young and broke, I used to keep used rubber bands in either talcum powder or corn starch and in a light tight container. I used to use one box for two models all summer long with never a problem. These days, I just throw them away. I suppose it varies with a person's finances and priorities.

Good flying.

Ed Cregger

Dan, Ed gave you good advice. Six rubber bands is definetly not enough since you started doing aerobatics. When you were flying around in circles you probably could have gotten by with just six. I go the talcum powder route and reuse the rubber bands, but only one additional time. I find they become too stretched out and they don't cost much anyway. While you are at it, check to make sure you haven't stripped out your threaded push rods ends or clevises. I've done this with my Avistar and was developing some slop in my maneuvers. It would only show up when I stressed the airplane during aerobatics. Joe L.

Hell yes! I'm surprised your airplane and wing have not parted company yet. Whoever told you the 1 #64 band per pound of airplane... How many airplanes does he have? In all the trainer instructions I've read, I remember them recommending 10-12.

There are two ways to tell if you have enough rubber bands before flying. If you can pry the wing away from the fuselage with any reasonable amount of force, you need more rubber bands. You can also grasp the wing with both hands near the fuselage, pick the plane up and give the plane a quick downward thrust. If the fuselage comes away from the wing, you need more rubber bands.

I've seen trainers with 8 brand new rubber bands come apart in the air.

You only used 6 rubber bands, AND you used them more than once? You should be able to use a set of rubber bands for an entire days' flying, then throw them away.

Dan,

On rubber bands: I would first put two on each side of the wing, then put two more in a cross pattern, then another one or two on each side. It wouldn't hurt to put one more pair in a cross pattern. At this point you would have

When I was beginning and felt a need to "economize", I would reuse rubber bands for a number of flights with the only maintenance of wiping the schmegma off after each day of use. Before installation, I would check for nicks and would pre-stretch to make sure they had enough elasticity and did not break. By the end of the season I would be using a mix of new and "older" bands. I never got burned, but was often "advised" I was being overly miserly. YMMD

On your loops: besides assuring your wing is on tight, try to throttle down a bit on the downward leg of the loop. That fast airspeed may be the cause of you "ballooning"

It's *two* #64 rubber bands per pound of airplane. Friend of mine had a Stik that did the same thing as was described by the original poster. He added two more rubber bands, and the problem was solved.

That would be one band PER SIDE per pound of weight, a 6 pound plane should have 6 bands PER SIDE for a total of 12 then add 2 more in X fashion to help keep the others from slipping off the pegs.

Total of 14 bands for a six pound plane

Thanks for all the advice, everyone! Sounds like I've been pretty darn lucky with the setup I've been using. I'll be doubling the number of rubber bands I've been using.

Good flying, Dan

snipped-for-privacy@aol.com (MEpst22487) wrote in news: snipped-for-privacy@mb-m26.aol.com:

Yep. Same thing happened to me. Had to add more rubber bands.

I had the same problem with a 60 size Ugly Stick. It wasn't until I was taking the wing off to go home that I realized that I had only put on four #64 bands. Always use at least 12 bands. And make sure that you crisscross about half of them. I witnessed a mid-air where one plane was saved because of crisscrossed wing bands. One of the wing hold down dowels was sheared off, and because of the cross bands, the wing stayed on.

If you want to be economical with your rubber bands but not have them break all the time, you can do what I do.

Rubber bands last me a long time. I build a lot of planes and sell them after flying for a little while, so I fly a lot of different stuff all of the time. I usually have a rubber band plane in the fleet. A box of rubber bands usually lasts a year or two.

Use at least 8 rubberbands #64 to hold the wing on. 10 is even better.

Criss/Cross the last 4.

After a weekend of flying throw them away. You can buy them in 1 lb. bags at Wal-mart and office supply stores cheaper than at hobby stores.