Many thanks to the various contributors on this. However " Instant weight and
balance" wasn't mean't to be about calculation prrograms where you have to
know things to input first - there are oodles of these about.
The idea is to read use the numbers required directly in the cockpit - the
calculation is trivial if you have any on board computing which accepts the
inputs without having to type them. If you don't yet have such a facility it
might even be a meter reading (but I don't want to get involved in that - too
low tech when there is a laptop sitting between the headrests, and a display
up front). You do not have to measure arms to get moments when they are
alredy known and fixed at the three points, though I did say you could input a
variable if you want to put things in funny places.
The key element is the monowheel weight measurement. Though described in terms
of the damper block compression, indeed as the top is fixed , the measurement
of the relative position of the bottom would do. In fact any point on the
arm would do, but the tyre does NOT come into it. It just absorbs the weight
by compressing enough to pass it on the to the arm. You could measure the
compression of the tyre instead, but that would a bit daft, as you need
something resting on ground and also start worrying about tyre pressure and
temperature too. At least one doesn't pump up the damper block !
Yes, it is valid to ponder on the possible variation of the compressibility of
the red stuff with temperature, moisture content ?, drift etc. (the OAT could
be fed in if it matters significantly) Such investigations could be done in a
lab. (Europa ?), but installed in the aeroplane I was hoping to fit a suitable
device and get on with it (yes LVDT's ring a bell) and yes please Dave, I
would appeciate a digital caliper source, hopefully with an interface-(
perhaps too much to hope for serial output ?).
Graham C. G-EMIN
|