RST Engineering - JIm wrote:
And after all is said and done, we remind ourselves that we are supposed to
be building inexpensive airplanes that look good and fly well.

So a vane on a synchro? Sure, we had those on the Boeing 3-holer (7-deuce)
at a cost of slightly less than $10k a copy in 1965 dollars. Surplus
synchros? Sure, now you are doing a one-off and how to tell another builder
how to use another brand of surplus synchro isn't feasible...not to mention
the fact that most synchros are set up to use the 115v 3phase power that the
Air Force/Boeing is so pleased with.

Or a gas tank sender with a big flap on it? Well, that looks like hell,
doesn't it? Besides that wirewound pot on the gas gauge needs some REAL
FORCE to push it around and consumes a fair amount of current in the
process.

Or some thermistors inside the pitot? WIthout a little more description you
can't tell exactly what the scheme of that is. One thermistor on the inside
top of the pitot and one on the inside bottom, each thermistor heated
equally (difficult task) and then you hope that the incoming air is laminar
and not swirling around? This might be feasible with a little more
explanation.

Differential pressure sensors? Haven't done the research lately, but the
last time I looked Motorola had stopped making the inexpensive variety and I
don't know if anybody else picked up that ball.

So, let's take it from scratch and think about what the optimum solution for
cost, looks, and reliability might be ... and the rotated yaw string is a
good idea except for the fact that 95% of the homebuilts are tractors and
the prop blast will decalibrate anything we might come up with...

Jim


Every aircraft synchro I have ever seen uses 26 VAC 400 hz single
phase. I have seen power supplies for them on e-bay for around $25 or
so. It's been awhile since I have looked, but they were there. In any
event synchro systems don't seem to be sine wave particular so a simple
power supply should be easy.

If you want cheap aircraft synchros find a shop that repairs jet
aircraft. The 1" "peanut" pressure indicators contain a synchro that
usually outlasts the internal lighting. I have found them on e-bay also.
Compass amplifiers such as used in the C-12 compass system contain a
multitude of synchros since they use a gear train to drive several
synchros. Vertical scale instruments such as those used on C-141 also
contain synchros. I have seen those for sale on e-bay also.

Dan, U.S. Air Force, retired