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The answer depends on what the multiplication factor of your winder is. I assume you mean 90 crank turns, which can be 1800 motor turns (20:1) or 1350 (15:1) or 900 (10:1) or 558 (6.2:1, yes such a winder is available commercially) or whatever. So you can see, comparing winder cranks without knowing the multiplication factor might mean you are OK and winding harder than you think. Or your technique might be lousy and you are breaking prematurely.

Another important factor is the quality of the rubber itself. How has your rubber been stored (high temperature, sunlight, and ozone (from electric motors most commonly) are NOT your rubbers friend)? Is it fresh (rubber changes over time)? How cut to width (are there nicks in the edge?)?

Do the curves yourself and you should see for competition, always wind to just short of breaking and backoff to torque that just bumps or misses the ceiling, depending on how brave you are. A common rule of thumb is you want to pick rubber to match prop so that the backoff is about the same as turns remaining on landing.

Jeff Anderson
Livonia, MI

Sorry, it's a 15:1 winder.

And I'm storing my rubber in a plastic baggie with a bit of lube in it in a pretty cool, dry, and dim place. I suspect knicks or maybe torque is to blame, since I usually get quite a few flights before a motor breaks. I'm working on my torque meter as well.

blue cobra wrote: Preferably a torque meter, but if not you can make a hook out of some stiff wire and attach it to something like a 3-inch C clamp and clamp that onto a table or the bleachers.

and you can bring that out onto the field with you when you are competing right?

I have a feeling I might be winding wrong. I can only really get 90 winds into .090 TSS. Maybe I'm winding too quickly or moving in too quickly.

Also, with regards to dewinds, how many are typical? And if I had to dewind, say, 5 times, and I wanted 90 winds, would I have to wind 95 times, then dewind 5?

what type of winder are you using? 1:?

Yes, you can bring your winding apparatus into the testing area (I saw one at States last year). They don't have to provide a table to attach it to (though they did at States last year), but most if not all areas are gyms with bleachers. And just out of curiosity, if you're in Division C, why are you so active on the Wright Stuff forum? Do you do things with flight outside of SciOly?

blue cobra wrote:Sorry, it's a 15:1 winder.

And I'm storing my rubber in a plastic baggie with a bit of lube in it in a pretty cool, dry, and dim place. I suspect knicks or maybe torque is to blame, since I usually get quite a few flights before a motor breaks. I'm working on my torque meter as well.

What is the Armor all Lube called

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Wright Stuff
Meteorolgy
Can't Judge a Powder

blue cobra wrote:Yes, you can bring your winding apparatus into the testing area (I saw one at States last year). They don't have to provide a table to attach it to (though they did at States last year), but most if not all areas are gyms with bleachers. And just out of curiosity, if you're in Division C, why are you so active on the Wright Stuff forum? Do you do things with flight outside of SciOly?

Thanks. It's because i'm doing helicopter, but if i post in the helicopter thread i wont get as nearly as good as answer as i would get here (and the principles for both events are the same). I also help the Div B school in my area but pretty much everything i ask is for myself.

Taran wrote:What is the Armor all Lube called

Try googling armor all origional formula.

jander14indoor wrote: Another important factor is the quality of the rubber itself. How has your rubber been stored (high temperature, sunlight, and ozone (from electric motors most commonly) are NOT your rubbers friend)? Is it fresh (rubber changes over time)? How cut to width (are there nicks in the edge?)?

This brings up a point i was going to bring up soon anyway. The storage of rubber. High temperature, sunlight, and ozone degrade rubber. Would putting rubber in a freezer be a good way of storing it? How long after aquiring the rubber does it begin to degrade if left in a cool, dry place but not a freezer?

Storing in freezer is common among hard core rubber flyers. Cool, dry, no light will keep it good for years, assuming its not a weird batch.

Note, I've heard that some kinds of plastic storage bags have plasticizers to soften them added that rubber doesn't like. I don't have evidence other than hearsay on this one, but its easy to avoid, so I just keep mine in the original cardboard box, or if cut up, in manila envelopes.

Jeff Anderson
Livonia, MI

I have noticed that at least half of the time when the rubber motor breaks, it breaks at the winder, often a fraction of inch from the knot.

Is this because of the extra instantaneous force exerted at the winder, or because of small tears that were formed when tying the knot?

Probably damage while tieing the knot. There are some knots that will hold well even if you lube the rubber, which helps protect against tears. I've seen fliers tie the knot under water to lube and the the water dries reducing knot slip.

Jeff Anderson
Livonia, MI