Someone recently posted about the dearth of posts here, so I don't feel too bad about digging up this old thread.
I've lost 3 or 4 clg's in thermals, perhaps more. Tip launched models are supposed to be better flyers, so I expect for them it would happen more often.
I've found silly putty timers reliable, but their speed changes with changes in temperature. A bit of research with a stopwatch and a thermometer might deal with that. I've made a Tomy timer myself. It wasn't too difficult, and the price was right. I understand it's possible to make them under two grams, unless memory fails me. That doesn't seem like much if you build a one meter span model. I suspect most designs at that span could use more area anyway, and therefore would be more able to carry weight.
I've seen a number of designs for homemade electronic timers that could be made cheaply. A motor timer design might work well if you used a PNP instead of an NPN, or vice versa, although I'm sure with an actuator or something it could be used as is. Here's one:
http://www.peterboroughmfc.org/technical-articles/web_site_FETtimer.htm Probably best if used with a supercap instead of a battery, to enable fast recharge and prevent damage if it goes flat. I haven't tried this yet.
As far as tailbooms go, I suspect a balsa one could be made just as stiff and light, but wouldn't be as pretty. My back of the envelope calculations seem to indicate that solid booms of balsa would be much stiffer and at least half as strong, and i think that the increased size of a hollow boom in balsa would give similar results compared to a hollow carbon boom. You could also make the section wider than it is tall, because the max load is during a cartwheel, and the maximum need for stiffness is in yaw at launch. It's also easy to put a custom taper on balsa. To save the trouble of a joint in the fuselage, a vane DT, as found in catapult gliders, might work, or the traditional pop up tail, released weight on thread which is attached at the tail, etc. could be used. Around here, we have a lot of reeds about the right size for tailbooms. One of those with a few strips of carbon on it might even outperform a carbon boom, except for increased aerodynamic drag. You can get scrap bits of carbon tow, etc. for $2/lb (!) at Soller Composites. Look under the tow section. I don't know how long they are, though. However, you can get 3k tow at $2 per ounce! (That's 470 feet!) The 1k is much more expensive, at $16/oz, but the length is much more. Or you could probably do better by slicing off little bits from a unidirectional carbon strip, if your local hobby shop has it.
