David,
I had an interesting incident a couple of weekends ago at a local jet meet. I had brought down my "basher" jet to fly and had the night before charged it's batteries (3). It's a little Velox and I am on Spektrum 2.4 powered by two 2 cell Li-ion batteries regulated through a Powerbox regulator/switch.
Anyway, I checked everything before the first flight and it was fine. After a few flights (5 minutes each, I was powering up for another one and I noticed one of the lights on the switch was not coming on anymore and the plane did not power up on the LH battery. I thought maybe it had a bad connection, so I unplugged it and then plugged it back in and it still did not work. I then saw the "clue light" flashing brightly in my face and I grabbed my voltage tester to check the battery.
The volts read 0. The battery, which had been at 8.3 an hour ago had commited suicide. I'm guessing it "died" during the last flight.
Thank God I was running a dual battery set up. While we can't "bullet proof" out jets, there are simply some things that for relative pennies compared to the overall cost of the project can make it much more reliable (safe).
Beave
ORIGINAL: David Gladwin
Really guys its unbelievably simple. Our models are TOTALLY dependant on a secure power supply. Without it they are DEAD, period. We CAN so easily gurantee that power supply by fitting TWO batteries, at minimal cost in cash and weight. A big hole plugged, dead easy and cheap in the big picture . Risk of battery failure is X, with TWO batteries its X squared , virtually eliminated . Why do you guys think that two of everything (sometimes three, but they still have just ONE main spar !) are fitted to things like ETOPS airliners, why does my boat have 2 batteries ? Why does my car (all modern cars) have THREE brake systems, my aeroplane (when I had it) 2 ignition systems ?
May I suggest you read the manuals of the Weatronics DRs and the Powerbox systems if my logic about power supplies is dismissed. The designers of these system are no fools, far from it.
Sorry, Ali, my big models do have TWO receivers ( Weatronic) and TWO power supplies. I CANT guarantee totally systems redundancy as even with twin servos on a single surface a burned out servo will make that surface immovable. Even my small models will soon have Weatronic Dual receivers (micros) on 2.4
However, there are situations where total redundancy IS possible and the critical situation of vital power supplies is just such. Not filling THAT gap is, in my opinion, just dumb !
Just my opinion, of course, but based on 40 years of R/c modelling (back to RCS Guidance systems and Flight Link Proportional) and 40 plus years of operating real jets, but what would Boeing etc. know ?
Funny thing is that I have bought hundreds of servos over the years, with perhaps two failures, I have a whole box full of batteries that have deteriorated to the point of being unuseable as main power supply. Go figure, as our American friends would say !
Regards,
David.
PS and yes large models DO place a larger demand on electrical supplies. Large digital servos moving large surfaces against higher dynamic loads equals greater current draw, elementary physics !!