Rubber Power questions

[Sparr]

I have never built a rubber powered model before. Where does one get the right kind of rubber? I am looking for rubber to power a 2-8g plane with a 3-4" propeller, but general help would be nice too.

[flailing]

Look in the Free Flight Resources thread most of the bigger shops have rubber, try www.sigmfg.com I think Peck Polymers has rubber also. You will need 1/8" for the size and weight airplane you ask about. The best rubber by far is the Tan rubber but it is no longer being made, a sad day. Some of my club members are having great results using plain old office rubber bands looped together, they are using a specific brand I will try to find out what brand, I do know there in a white box with green and gold trim.

[BMatthews]

Sorry flailing but 2-8 gms is peanut or penny plane territory. Sparr, I suspect you'll be looking for smaller sizes like 3/32 or even 1/16 for the 2 gm stuff. Actually you're getting into indoor sizes and they measure the rubber is thous, ie .050, .055, .065 etc. You'll be wanting indoor supply places for these sizes. Pecks has some for peanuts and the like but I don't know if they have a full range or not.

FAI model supply has 3/32 and 1/16. The jump may be a little coarse unless you're just sport flying.

[Bob Chiang]

If you have never built a rubber powered model before, I would not suggest such a light weight type to begin with. When I built a Penny Plane I accidently broke it at least twice during the building process, and this was after many successful rubber models. Depending on what you build, many of the very light weight models actually use quite large props that turn slowly in order to extend the motor run.

Here are a few suppliers of rubber and related supplies:

http://members.aol.com/IndoorMS/IMS.htm
http://www.aeroaces.com/aeroaceshome.htm
http://www.freeflightsupplies.co.uk/
http://www.pennvalleyhobbycenter.com/rubber/supplies/rubber.htm

Bob Chiang
Ithaca, NY
(love rubber, but not the light indoor stuff- at least not yet).

[Sparr]

Actually this isnt for a plane, it is for a helicopter. A matchbox helicopter at that, although I might scale it up a bit.

[flailing]

2-8 grams is a really wide weight range I went for the 8 gm. I have been flying 7-8 gram peanuts for years on 1/8 rubber, it must work I have won many FAC competitons in peanut scale aginst some pretty tough competition, my p-nuts eaisly do over a minute outdoors. If I were flying indoor I would use smaller rubber 3/32 or 1/16. I assumed he was talking about a peanut model and a beginner p-nut is more likley to weigh 14+ grams, a 7 gm p-nut takes a lot of skill.

[Bob Chiang]

I'm interested in the helicopter you plan to build. I've built three rubber powered helicopters. The simple no-cal types are fun, but the counter-rotating type are very impressive flyers. I'd be happy to e-mail plans for the simple types. The duration model was designed by Stan Buddenbohm.

[BMatthews]

Originally posted by flailing
2-8 grams is a really wide weight range I went for the 8 gm. I have been flying 7-8 gram peanuts for years on 1/8 rubber, it must work I have won many FAC competitons in peanut scale aginst some pretty tough competition, my p-nuts eaisly do over a minute outdoors. If I were flying indoor I would use smaller rubber 3/32 or 1/16. I assumed he was talking about a peanut model and a beginner p-nut is more likley to weigh 14+ grams, a 7 gm p-nut takes a lot of skill.

Ah, fair call then. I only built a couple of peanuts way back when and they were both for low ceiling indoor use. If I'd put 1/8 in them they would have been trying to cut a new vent in the roof.... :D

And I'm sort of curious about this helicopter too.... Links? Pics? Plans? ..... and a matchbox size to boot. Too cool.

[Sparr]

http://home.att.net/~mybeasts/MatchboxCopter.gif

That is the original, it flew for 25 seconds on whatever kind of rubber they were using, which was enough to win the matchbox competition it was entered in. I am thinking it will be a great platform for my first attempt at a palm size RC heli, perhaps scaled up to 200-300%.

[peteypete]

WOW ! that's small. It makes my peanuts look big. What's that protrusion foward of the upper prop that measures .6 in.-- are the lower blades fixed or do they rotate-- is there any curve in the blades or are they flat ? I started building the Peck/penny copter but was a little confused about the tail rotor and put it on the shelf. this looks like fun and a little simpler.

[Sparr]

Yeah, it is built to Matchbox scale (http://home.att.net/~mybeasts/matchbox.htm). That is an EXTREMELY tiny scale, all models have to fit, in their ready-to-fly form, inside a large matchbox which is 1-3/8" x 2-9/16" x 4-1/2". I havent built it yet, dont have any rubber, but upon re-reading that page it seems like they are using the rubber strands inside a bungee cord which I think I can get my hands on. I can answer those questions though :). The protrusion ahead of the prop is the prop shaft, it protrudes so the model will 'walk' on the ceiling instead of the prop blades hitting and stopping. The lower blades are fixed, they divert a small % of the thrust sideways to neutralize the torque of the main rotors. No curve to the blades on a model this small but I bet someone with some aerodynamic knowledge could tell us how to curve them to make it a more efficient flier.

[BMatthews]

Ya know? That looks kinda familiar......

In my mind I'm seeing a pic of a guys hand with a matchbox and a little heli like that inside it. And it's very old and yellowed paper that the pic is printed on. I think it was back in the 60's when the magazines were printed on that cheap newsprint.

Am I close? Do I win anything...... :D

[steve lewin]

Unless my eyesight is worse than I thought it looks like a micro version of a Ceiling Walker as in http://home.att.net/~dannysoar/CeilingWalkerVol1.htm.

We were talking about them here a while ago (I'd never seen one at the time). http://www.rcgroups.com/forums/showthread.php?s=&threadid=51993&highlight=ceiling+walker

OTOH I'm not sure what you're going to R/C. I can't see much on there to control :(.

Steve

[Sparr]

We have been discussing palm sized helicopters over in the micro heli forum and this airframe seems suited. both because of its extremely low CG (relative to the rotor span) and because it doesnt need a tail for yaw stability. The basic idea is to use coils mounted on the airframe directly under magnets mounted on the rotors. Energize the coils in pairs, one + one - and you can get the rotors to tilt, a virtual swashplate. 4 coils and 2 magnets would work. add a RFFS100 and a small motor with the appropriate gearing and you get an AUW of 11g+X where X is the weight of the airframe, and you can get 15-30g of thrust out of a small motor with the right gearing, so hovering and climbing will be no problem.

[flailing]

The rubber bands I mentioned are Alliance brand, they have 1/16" bands in 7 different lengths from 7/8" to 3-1/2". My clubmates are using them for a subsitute for the TanII rubber with very good results, should fit your application well.

[yfm1]

On my site I sell FAI Tan rubber. 24 feet of 1/8" for $2.95. This usually make 8 to 10 morors. MY site is www.fly-m.com

[KnifeEdge51]

So, I went to the Penn Valley Hobby Center website, and they have a wide selection of TAN rubber to choose from. I'm looking for a large amount of rubber for p-nuts, walnut sized planes, and some scratch stuff for the SO competition next year. Would I b better off getting Mini TanII in feet, Tan Sport in Pounds, or Tan Super Sport in pounds? I don't know the difference really. :) Also, if I can find some regular TAN II, should i spring for that instead?

And, how do I store rubber for long periods of time? Put it in the fridge? :eek:

Nick R.

[yfm1]

TAN II rubber is no longer made. There is some around in individuals hands. Is it worth buying? A limited supply that will increase in cost and deminish in quality with age, should you buy?

At some point all will be changing to TAN Super Sport. May as well do it now. Learn how to make TAN Super Sport perform to it's best and save the money chasing history.

If you use large amounts of rubber buy from FAI Model Supply (faimodelsupply.com). If you use small amounts buy from my web site fly-m.com.

Have a fantastic day,
Fred Matthis
yfm1@macatawa.org

[KnifeEdge51]

Fred,

I checked your site for the TAN II tubes that are on there. I saw them a while ago (a number of months) and never did buy any. Using the link to your ebay store, I found you didn't have any.

There is a 1 pound box of 1/16" Tan II on Ebay, produced January of 2001. That is old, I guess, after thinking about it.

Out of curiosity, how does the Super Sport compare to TAN II? In any case, I'm most certain that it's infinitely better than the Guillow rubber I find locally. Too bad none of my local shops carry any serious FF stuff. But I guess that's where EZone comes in. :) Thanks!

Nick R.

[BMatthews]

IF the rubber was stored in a cool dark place, like my basement refrigerator, then it's fine even if years old. In fact there's some historical info that used to say that cool aging the old Pirelli was good for it's power output.

If the guy with that box 'o rubber stored it properley then it's fine. If it sat in the box on a sunny window then it's useless.

If you don't fly often and don't overstress the motors up to max torque then sport model motors can be kept in the fridge between sessions and can last for many flights before the edges get nicked too much and you risk a blowout. Check your motors before installing for nicks and tears along the edges of the rubber. Small corner slivers are OK for sport flying but any slivers that have grown to a tear that spans the distance between two corners of the strip is reason to toss it. I've found that once a tear spans two corners it's a short trip to a blown motor. Minor power test flying is OK but even 75% is going to shred things sooner or later.