A Note on Rubber Bands - Page 4 - RC Groups
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Mar 25, 2012, 08:58 PM
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It has nothing to do with your question....but the age of the post...I don't think I've ever seen one this old
I have never had a new rubber band break on me.....I am a firm believer in using rubber bands only once.....I cut mine off when I was a student I encourage my students to do the same.....I use #64's from office supply stores.....
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Mar 25, 2012, 10:14 PM
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The predictability of nylon bolt shear characteristics is ummm...unpredictable. I've fixed too many planes for people that had fuselages torn apart to believe they're a reliable damage mitigation system.
Mar 25, 2012, 10:32 PM
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ckreef's Avatar
Originally Posted by NACA0012
The predictability of nylon bolt shear characteristics is ummm...unpredictable.
I thought Nylon bolts were all about the bolt breaking before the wing broke. I don't really subscribe to that so ...........

Why Nylon Bolts ??? Steel hex head bolts and then no worries.
Mar 29, 2012, 10:47 AM
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Toysrme's Avatar
just to start, its silly to continue a post this old....
buy HOBBY GRADE rubber bands. I've used TWO boxes of Hobbico #64 rubber bands in NINETEEN YEARS OF FLYING. the current box im pulling rubber bands from is Hobbico via a LHS has a trademark of 1992! If you're tossing hobby grade rubber bands off after one use... wow that's moronic...
  1. the band has not deteriorated to chemicals or UV
  2. no cuts in the rubber band (obvious as you begin to stretch)
  3. stretch it until its pretty much done
you may re-use the rubber band indefinitely.
youll also notice when you buy a box of hobby grade rubber bands that they come with a lot of cornstarch in the box...

AFA nylon wing bolts. yes, it is pretty rare to "properly" shear off a standard 1/4" nylon bolt. the only plane i've ever done in my 19 years of flying in person was a 12 pound 1/4 scale cap. (and for the record, it's wing bolts were taken from a real estate sign & "had seen some use"...)
i've never, ever had it happen to me, or seen it happen in person from .60 size (1/6 scale) & under something else fails before the bolt does.

what i've seen most often on planes less than around 10lbs is that the bolts are strong enough to pop the blind mounts back out of the ply/hardwood wing saddle in compression. they simply rip the entire wing saddle out of the fuselage, or the wing is simply not strong enough wherever it impacts to "survive very well". (caving in large sections)

more than anything else, the point of nylon wing bolts is brevity during plane assembly & looks.

i've seen a lot of kits & arf's over the years swap from 1/4" nylon bolts to small steel hex bolts with washers & back. same problem.

if you put a 1/4" nylon bolt on a .40 sized plane and expect it to save anything, you're kidding yourself.
if you put 12+ rubber bands on a .40 sized plane and expect it to save anything, you're also pretty well kidding yourself.

if the typical application is a .40 sized trainer. 8-10 rubber bands is sufficient. 1 pair straight, next pair crossed (under more tension). if half of the break in flight (ya right) that's STILL more than you need to land on....
use 4-8 on smaller park flyer planes, or gliders. no point in crushing foam, or thin balsa...
Mar 29, 2012, 10:51 AM
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Toysrme's Avatar
one thing brought up by Wingwrecker a couple years ago is def true. if you over torque your nylon wing bolt. i guarantee you eventually what's going to happen is that the head of it will pop off the shaft.

i've seen that in flight & after landing.

sadly it doesn't matter if you're sniping old UV ones out of real estate signs, buying new at sign/bolt shops or ordering them new. quality is all over the board!
Mar 30, 2012, 12:26 AM
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About the nylon bolts breaking, they do brake before the wing. I maidened my cub on floats the other day and ended up hitting the wing on one of my neighbor's wood wall around his shore line. I pulled up the nose just in time so the fuse didn't hit, but the wing hit into the wall and the bolts sheared and the fusealage was safely sitting flat on the floats on the grass in my neighbor's front yard. Of course the wing had a little dent in it, but a peice of balsa and some sanding and it is good as new. I don't see the point of rubber bands anymore.
Apr 04, 2012, 01:16 AM
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Yes you can use inner tubes. One of the old fellas out at the club uses them for all his planes. They are mainly cubs, scorpions etc and nothe aerobatic. He just flies planes that fly
Apr 05, 2012, 02:45 AM
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DL8698's Avatar
Originally Posted by scrubmonkey
Yes you can use inner tubes. One of the old fellas out at the club uses them for all his planes. They are mainly cubs, scorpions etc and nothe aerobatic. He just flies planes that fly
I have flown my Yamamoto (its a trainer) a few times with a single band each side in X pattern. But I am keeping my +ve G's on the low side as not sure how strong the bands are. However, just by pulling on them they sure seem pretty strong.
Apr 05, 2012, 08:40 AM
EIEIEIO Classic is dway ta go!
flyinwalenda's Avatar
If you can find NOS hobby rubber bands use them. The new ones are not very good in my opinion. Have many pilots using them and they either break upon installing, sitting on the ground waiting to fly, or in flight ! Plus they are only good for one session as there is no resiliency.
Apr 06, 2012, 03:46 PM
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Probably 20 years ago, the fact that Nylon bolts rarely actually fail was addressed in an RCM column, possibly by Chuck Cunningham. There were a couple suggestions, one of which was that the axis of the bolt has to actually be perpendicular to the wing/mounting plate line. The idea was that that way, the shear force is along the actual diameter of the bolt. If the bolt comes though the wing at an angle, the effective diameter of the bolt is increased, also increasing the shear strength.
Another suggestion was to use a razor saw to partially cut through the bolt along the wing surface to reduce it's cross section.
Frankly, the very rare times I've had Nylon bolts fail on an unintended impact, the rest of the plane was ready for a body bag. But, I've actually had rubber bands fail with only a minimal amount of damage to the plane.
And sadly, since around 1962 when I added rc to my hobby/sport addiction, I've had two planes come down from having rubber bands let go in flight.
Apr 06, 2012, 04:31 PM
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Most people use much to large a nylon bolt. In most cases a 6-32 or an 8-32 will handle most 1/4 scale and smaller models. I use 8-32 on my biggest 1/4 scale with never a failure.
Apr 07, 2012, 10:07 AM
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Alex Koehn's Avatar
Well on my escapade that my friend crashed its running 1/4-20 nylon bolts and it sheared one of them on the wing that caught the ground with no damage to the wing mount points. It caught the ground hard enuf to crush the wingtip...
Apr 07, 2012, 02:57 PM
222 km/hr Parkjet flyer
solentlife's Avatar
Using Office supplies rubber bands is IMHO a non-starter for me.

I have always used Hobby Grade bands that are wide and designed for the job. I may live in Latvia - but I buy via internet Ben Buckle Bands from the UK. They may cost a bit more than your office shop jobs - but they last months ... not flights and are about 1/3" wide ...

My 61 powered aerobatic biplane has banded top and bottom wings with no interplane struts. 6 Ben Buckles are more than enough for each wing. First I put one each side fore aft ... then another one each side. The last 2 are crossed over to not only provide wing hold-down .. but also a positive pull to keep bands on the dowels. If you tried to put 10 or more on - you'd crush the wing.

So my advice ? Get rid of those cheap office bands and use the proper bands.
Apr 07, 2012, 03:57 PM
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Years ago, near St Louis, I went out to fly free flight models on a day with Ozone warning. I could not get the airplanes together because the rubber bands would immediately break when stretched. These were not Hobbyco rubber bands, but never-the-less. After this happened to me twice, I quit trying to fly on Ozone warning days. I understand that Ozone meters use a stretched rubber band, but have never seen one. I suppose nylon bolts are not affected by Ozone.
Apr 13, 2012, 06:43 AM
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Oberst's Avatar
Originally Posted by dbruening80
Most of today's trainers use #64 rubber bands to attach the wings to the fuselage. Please, Please, PLEASE use at least 12-14 rubber bands when attaching the wing and ALWAYS CUT UP and THROW AWAY the rubber bands after each flying session. A few flyers at our field recycle rubber bands by placing them in a baggie filled with corn starch, IMO this is almost asking for trouble. Not only does fuel oil deteriorate (sp?) the bands, but the UV rays from the sun breaks the rubber down as well, while the corn starch could remove the oil, it will do nothing to reverse the sun's damage. Rubber bands are cheap, planes are not! (Personally I would rather crash my plane beacuse of something my thumbs did than have some sort of mechanical failure ) I also cut mine up after I witnessed a new flyer at our field pulling old rubber bands out of the trash and putting them in his baggie for re-use. I know the hobby can nickle and dime you to death some times, $7.99 for a plug, $5.00 for glue etc etc, but hey, a one pound bag of #64 rubberbands from office max is around $3.50. Sorry to rant, just somrthing to chew on
I agree and know where you are coming from. Very good advice in my opinion. However, I do re-use mine for about 4xs then I check and decide if I need to replace them or not. The Hobbico #64 tends to last for quite a few flights before they get stretched out and become not so trustworthy.

Last edited by Oberst; Apr 13, 2012 at 06:49 AM.

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