USING RUBBER - SOME TIPS FOR MAXIMUM PERFORMANCE
One of the many benefits of flying in competitions is the fact that you have to learn about using rubber effectively at a very early stage. F1D has made this even more important for me, as each turn you get on increases the potential flight time by over a second when the prop RPM is only 46.. Thanks to much help from the top flyers and time spent testing samples, I have learnt much which I thought mught be useful to NORWIND members. I find it really frustrating to watch really competent modellers limiting their performance because of a lack of understanding, or even sheer laziness! One flier had a well built Penny Plane which was clearly underperforming. When I suggested a rubber size, he told me that he couldn't be bothered to weigh a bit of rubber!. So.. I hope you will find the following comments to be helpful:
1. MYTH - YOU HAVE TO HAVE THE BEST RUBBER TO WIN.
If you are flying an F1D in the World Champs, this will be true. Otherwise, it aint necessarily so! Rubber is like wine. There are vintage years and well stored rubber will perform better. A rough guide to vintage is as follows:
The best - FAI May 1999. If you have the chance to get any of this buy it! It is in a league of its own,
Second choice - either October 1997 or March 2002. Both will give a very good account of themselves. Oct 97 seems to have higher torque, but I get a better cruise on Mar 02.
FAI Super Sport rubber should not be discounted. Two years ago, the Penny Plane comp at the Velodrome was won using Super Sport. I have tested some and have found it to be nearly as useful as Oct 97, but much more brittle. Two good winds and it broke or was really tired!
Whichever rubber you use, you still have to test and select from your stock, because it can vary enormously. I have a VERY small amount of May 99 and have found that some (from the same stripping) will add 20% to my best flight time, while other bits struggle.
2. LOOKING AFTER YOUR RUBBER
The enemies of rubber are grit, light, heat and air. I keep my rubber in an airtight sandwich bag, in a really cold place (preferably the fridge) and well away from light. My October 97 was bought about then and is still as good . Lubrication is crucial. There are different kinds of lube. Some fliers swear by soft soap and glycerine. Some by castor oil, I use a silicone lube which I get from Mike Woodhouse. If you use soft soap or castor, it is important to wash the lube off and dust the rubber with talc after each outing, otherwise dried particles can shatter a motor. I find that castor ruins a motor over time, but silicone seems to preserve it. (This is controvertial territory, but is my experience for what it is worth).
NEVER leave rubber wound up in a model between flying sessions. The rubber takes a "set" which seems to weaken parts of the length. I emulated the UK team member Tony Hebb for the storage of my made up motors. I keep each one in a seperate ACID FREE 2" x 2" white envelope of the kind used by coin collectors. You can buy them in lots of 100 very cheaply from Ebay. Each envelope has the details and history of the motor written on it, so I can keep track of how many winds it has taken,etc.. The envelopes are kept in a neat storage box which cost me the princely sum of £5 for two at B&Q!
3. STRIPPING AND TYING RUBBER
While it is possible to make a cheap, homemade rubber stripper, getting a consistent cut is virtually imposisble. Rubber strippers aren't cheap, but as a lifelong modelling investment it is a no brainer! Several of us in the group have strippers. I use a Harlan stripper from the USA. Buying ready stripped rubber is unsatisfactory for several reasons: You never get exactly the size you ask for, you don't know what quality you are getting and by the time you have done a bit of testing, it works out to be more expensive per motor! If you have some rubber which you need stripping and you really can't get the cost of a stripper past your personal Chancellor of the Exchequer at home, then come and see Dave, Tom or myself.
When most modellers begin, they strip their rubber in widths of thousands of an inch. As you progress, you inevitably change to using weight instead of width. I strip rubber using grams per meter (eg about 1.3g/m for F1D). The reason is that different batches of rubber come out at varying thickness. Oct 97 is .042" thick, but Mar 02 is .040" thick. Such a difference sounds small, but it can make a huge change in energy available. If I work in grams/cm, I can interchange motors much more easily. Obviously it takes a bit more effort to do a test strip (of say 10cm length) to establish the weight per metre, than it does to check it with a vernier or clock gauge, but it is worth it.