Initially you will buy pre-stripped rubber from one of the UK suppliers, this will be SuperSport, recent batches are not bad at all.
The sizes you choose to buy would be that recommended and shown on the plan by the model designer, it is a good idea to also buy a size either side of this to accomodate variations in model weight, ceiling heights etc.
Here’s an article what I wrote about stripping rubber.
Here’s an article on making up motors and here some information on using partial motors for testing.
Peter Watt from Northern Ireland let me have this piece about his experiences with rubber testing. You could use the spreadsheet I’ve included below to record your test results.
Carl Bakay wrote an interesting piece on rubber generally, click here.
Did I say wind? Well for that you will need a winder, “stooge” and Torque Meter.
There is a nice simple yellow plastic KP 10:1 geared winder available.
The stooge is just a piece of wood or metal that holds your torque meter and allows you to dock the winder once the motor is fully wound. Clamp the stooge onto your table – most competition flyers use a heavy camera tripod to hold their stooge. This is simply so that they can wind out on the competition floor near to the launch point thereby having a fully wound motor on the model for the minimum time.
The Torque Meter can be really quite simple, either home made or engineered – there’s a simple one to get you started on the INAV site.
If you want to make a non engineered example the write up is here and also a drawing.
Once you become more adventurous you will want or need (!) to strip your own rubber, for this you will need a rubber slitter. The only commercial one available at the moment is the Harlan one from the US based Indoor Model Supplies.
Of course you will also require that scarce commodity known as TANII, unfortuanately not just any old TANII either but only one of the best vintages will do. This is only available through contacts in the Indoor community. So get out there and fly, show them you are worth the investment!!
Once you get the good rubber remember to store it in a cool, dark place – the fridge is good!
Keep your made up motors and stripped rubber in Ziplock food bags, they can be labelled with DVD marker pens. Do be meticulous about labelling – nothing worse than not knowing what you’ve got in a bag.
Testing – when I make up motors from new rubber I like to test them to see how they compare with other known samples. This is a Spreadsheet of 4 recent tests I ran, you could use the format to substitute your own results.
Basically, having broken the motor in, I then give it a competition wind to about 30gm.cm and record the torque readings as I unwind at 10 turn intervals (one turn on the winder).