Correct camera procedures for double hang test

[WEST OZ FLYER]

What is the camera techniques for eliminating parallax errors with double hang tests?

[Disco]

Maybe take your tripod back really far with a telephoto lens might help. Some one correct me if that"s wrong please.

[bones]

Just need to make sure your camera is exactly 90* to the machine,actually the mast, just far enough back to get the whole machine in the shot, i drew a line on the concrete, and squared off that for the tripod, and then made sure who was holding the machine that the keel was lined up with the mark on the concrete. well that worked for me anyway.

[birdy]

I had no help and the wind blew the dog off the chain, so i fotoshoped mine.

[GraemeMonro]

I had no help and the wind blew the dog off the chain, so i fotoshoped mine.

[gyroo]

Howdy West Oz Flyer,This is an excellent question, because parallax can become a real issue if people aren"t careful to avoid it.In late 2010 and 2011 about 45% of the then-gyro fleet was double-hang and double tilt-back surveyed because at that stage ASRA just wasn"t able to tell CASA how many and by how much Australian gyros were High Thrust Line. No-one knew. No-one.The survey showed that most gyros tend to be high thrust line in the region of 5 to 8 inches, with 6 to 7 being pretty much the norm. While these measurements are outside the "plus or minus 2 inches" advocated by the UK Glasgow University research, ASRA doesn"t consider this to be too much of an issue, because self-evidently our gyros aren"t PPO"ing anything like they were 20 years ago, here and in the US. The fleet survey did, however, turn up a very small number of very high thrust-line machines (10 to 14 inches), usually characterized by having the seat down close to the keel, fuel tank (if not a seat tank) right on the keel, heavy undercart, then a heavy Suby behind the mast complete with HTD belt re-drive orientated up, meaning the prop axis was a good 8 or more inches above the crankshaft axis. ASRA didn"t move to ground these, and decided that because the owners now knew they were very high thrust line that this knowledge alone would probably prevent their owners from maneuvering into PIO or PPO. It was anticipated that these really high thrust line machines would be recognized by all as unsatisfactory and that registrations would lapse on them as they fell out of favor, or that they would be modified to bring them more toward CLT. This has more or less happened, as the general membership has become much more aware of thrust-line / CofG considerations.Interestingly, no stock-standard unmodified RAF owner submitted any survey pictures, but 2 modified RAFs were surveyed. By doing some math, and extrapolating from the results of the modified machines, I was able to calculate that a stock-standard unmodified RAF 2000 with HTD belt re-drive and with full seat tanks and 2 x 90 kg occupants is likely to be 13 to 14 inches high thrust line. I would really love to get my hands on one to hang-test and tilt-back test to see if my calculations can be verified.

[WEST OZ FLYER]

Thanks guys.That is how to answer a question Mark I had the Bones method in mind but this was the bit I wasn"t sure about. The camera must be raised on the tripod so that it is pointing to more or less the same point it was during the hang test,I had no help and the wind blew the dog off the chain, so i fotoshoped mine.