Electric Flugbox

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Electric Flugbox

Post by Igull » 01 Jan 2019, 20:56

Hi All

Happy New Year to everyone !

Been building this for a while and finished it last week, this is v2, as v1 - while exactly the same shape, had the wheels across the narrow width to get through our flying field gate (the gate is split to stop motorbikes getting through :-) ) Bad move as it was qute unstable when being towed across the field - it also caught the heels - which is why the quick-release handle is offset on v2.

The whole thing is constructed from 6mm liteply (to keep overall weight down) - actually 6.35mm - 1/4" - stuff that doesn't cut well on my laser due to the adhesive used during manufacture - the regular 6mm liteply is fine - it's also 100g heavier per sheet, but is great for this application :-)
It's split into four sections - tool drawer, heated battery compartment, tx drawer and empty top section for flask/sandwiches/beer etc

The only interesting bit is really the heated battery compartment. The lower section of the flightbox splits away to form a seat (the leather upholstered top is yet to be done :-) ) with the heated part in the box under the lid. The heater is simply a 2mm alloy plate cut from an old electronics front panel I had (400x200mm). Mounted on the plate are 8 x 0.75 ohm 10W resistors in series. The only decision for the resistor values was that they were the cheapest on fleabay at around 10 quid for the 8 shipped. The value was fine as 8 x 0.75 ohm gives 6 ohms at around 2A at 12V for 24W - I just use a 'knackered' 3S LiPo for power- of which I have a few - 2A isn't a great pull - even if it looks like Billy Bunter :-) I considered 12v silicone heater mats, but this method offers more flexibility.
TBH, you don't actually need the temperature controller if you're careful, but I thought that for safety (*?), having some control was nice - it was a fiver from fleabay inc delivery and also included a temp sensor and a built-in 20A relay contact set. I used it in earnest a couple of times last week - first time was around -0.5 to +1.0degC at the flying site - I kicked off the heater when I stuffed the gear in the car - about a 1/2hr drive and it was at 21degC - I have it set for 25degC - the compartment was literally FULL of batts (not a great idea - completely unnecessary and adds extra load to the heater - and the hernia :-) ) - it got to 23 and stayed there.
Next time was a couple of days later at around the same temp - battery compartment only had enough batts for flying that day - maybe around 12 or so. Temp at 25degC was easily achieved and it clicked in and out all morning - changed the batt early afternoon. I have a low batt howler plugged in to the balance lead - that is a good warning system - although , a DIY controller and batt switch off would be nicer :-)
BTW, it will run on 4S just fine - gives about 42.5W for 2.7A.

The whole thing was also designed to fit the passenger footwell in the car - it can also be split and strapped to the back of the passenger seat for safety if I have a passenger. Wheels are 200mm dia - adult scooter from Decathlon.

BTW, the controller is simply an off/on type, not PID.



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