see belowL
Simon Van Leeuwen wrote:
Comments inserted;
Lincoln Ross wrote:
snip
I wonder if anyone has tried using the tailboom for an antenna? How
about the wing spar for the ground, i.e. negative, power wire? For
reference, for another project I measured a carbon tow at 25ohms/ft.
Not sure which type.Not sure how many tows in one of those spars.
Not a silly question - but carbon is dissipative by nature, so
definitely no. The electrical losses would be huge.
Well, what about the power wire? That's DC, isn't it? I don't know how
many tows equal a spar, though. It would have to be a lot.
Seems to me those dedicated wires are just extra insulation. For that
matter, you could drop the insulation on the negative wire. One could
use one big wire, as someone else mentioned. And a little wire for
the signal. If you're worried about reliability, one big wire makes
it easier to have redundant pins. If you use double pins for every
function, that's 12 pins per wing. One big connector, perhaps? Also,
if you're worried about reliablility, make sure you use very careful
strain relief. Probably using really fine stranded wire would help
with the reliability as well, but I don't know where to get it,
particularly on a budget.
Again, I challenge anyone to demonstrate a win or loss becuase they
carried slightly more or less mass equating to approximately an ounce.
I challenge anyone to demonstrate a win or loss due to anything except:
1. practice
2. ability
3. failure of the airplane, radio, health of the pilot, etc.
4. complete inadequacy of performance. I used to beat Windsongs with a
Sagitta 600 (43 oz)
Proving things is hard.
I challenge anyone to demonstrate a win or loss because of 1/2 sq. inch
flat plate perpendicular to flight direction. (Or, at similar drag
coefficient, a cylinder. Can anyone say "launch peg"?)
Anyway, I'm ruined because for a while I built EZB's.
The drive to have the lightest mass is not warranted except as an
excersise to show it can be lighter. Other systems are being
compromised for what? It just won't contribute to a win or a longer
flight given current L/D's. As it stands now there exists viable
conector options in very small form factors that allow each of the 4
servos in an F3x wing to have PWR/GND along with the SIG.
Yeah, but in the other system you can lose any one pin with no effect at
all. Probably needs to have a diagnostic, I suppose. (I'm sure your
systems are very reliable. Your soldering, strain relief, and attention
to detail are probably much better than us occasional hackers.)
One known reliability issue is for those systems that the enduser has
to literally connect and disconnect connector systems by hand.
Yah, that's a scary one. 1000 feet, minute and a half to go, no spoilers!
As far as strand count goes versus flexibility, 7 strands in 24 or
22awg is more than adequate in this scenario. I build plenty of
plug-and-play harnesses for IMAC-style giant gassers that employ 7-9
strand that have experienced zero fatigue-failure. This environment
offer significantly more chances of fatigue-failure scenarios than a
sailplane ever will.
That's good info. Thanks. Maybe I can relax about the "lousy" wire I found.
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