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Aug 13, 2019, 10:24 AM
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1kW Funcub reinforcements for towing?


Hey fellas, got a Funcub kit arriving today, going off the menu ordering parts from five different vendors. Kind of ludicrous admittedly. I'd use a giant-scale but I'm lazy for transporting. Dealing with stripping stainless steal screws in the winter with numb fingers, no thanks. So, question about building an overkill tow Funcub (about 1kW), judging from a video of one of you towing a couple gliders vertically using the setup I'm trying to mimic, and at least one of you using reinforcements with the motor mount. Is not metalsmithing reinforcements something I'll immediately regret? I'm not very competent...

Vertical funcub (1 min 13 sec)

Regarding being a reliable go-to tow man (once I've gotten more comfortable with the piloting -- not so easy), I realize charged batteries are an ingredient. This is tough to calculate, but on-hand I have four four cell four amp hour packs, maybe I'll get four minutes tops out of each, plus some extra time between tow hookups and charging swaps. Close by I'll have a briefcase with three chargers powered by a bunch of old jumbo packs in parallel. So rotating in after each depletion a pack to recharge, taking out a charged pack, three packs charging at 1C at different steps of progress, might that be about enough to keep on towing without having to take a break? Because towing is a high current operation, pushing the packs to their limits, if I need to charge faster, would charging at 2C given the abuse of this sort discharging I'll be inflicting not be that significant in terms of hastening the frequency of my having to buy new packs?

That was tricky to articulate, let me try harder: For you tow guys who are in demand at the field on a perfect day for gliding, how many packs and chargers would be nice to have with you, or what could you get away with, in terms of continuing to tow without interruption to finish recharging (until you exhausted your chargers' source)? If you want to tow almost constantly for a good two or three hours and you get a good rhythm going, how many kilowatt hours does that sound like? Yes, I know, many variables... The reinforcement question is more important.

Muscle Funcub, cheap towplane. (2 min 31 sec)

By my math the additional weight of a 4250 motor, a juicy ESC and a 4S 4Ah pack versus a normal configuration, that's about another 500g, and in front of what would have been the CG. Strong, raked gear would be nice, like what I found in the Funcub thread, but don't know where to buy it. Maybe I don't need it and should put that money into life insurance should I forget that throttle cut switch. Any pointers would be appreciated! Thanks!

Doug
Last edited by Doug Simmons; Aug 13, 2019 at 10:30 AM.
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