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Old 22nd Aug 2017, 12:52
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john_tullamarine
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Join Date: Apr 2001
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you are obviously not old enough

.. only a year or three behind your good self ...

the ‘stoneman’ technique.

When this exercise started (at that stage I thought it was nonsense .. that idea was corrected instantly the first time I watched - wide-eyed - as the Diesel 9 disappeared stage left/right as the case may have been off the video monitor) we had no guidance on how to go about it (that sounds regularly familiar over the years) so we sat down over a beer or three and tossed around ideas.

The prime requirement I had was that we wanted to achieve a defensible error less than 6 inches (no metrication nonsense for us).

Rapidly, we discarded a bunch of ideas including such as

(a) estimating deviations from the runway head or side (too much hit and miss and too hard to run a sensible error analysis) - near enough to the stone man technique, I guess.

(b) side looking video using stock standard domestic video kit mounted in the aircraft and looking out a window (what about accounting for aircraft rolling motion ? - bin that one, too)

(c) sand dispenser attached to the aircraft (the chap who came up with that idea bought the next round after he couldn't quantify just how he proposed to allow for lateral accelerations and so forth)

Fairly rapidly, it came down to two options

(a) a long lens video at the runway head, or

(b) a couple of strap down INS units (which wouldn't have given us anything in the way of a significant improvement in accuracy and .. did I mention that the extra-aircraft operating test budget was measured in cents rather than dollars ? .. scrap that idea)

The biggest problem then was to figure out how we were going to go about the exercise.

(a) WRE, as I recall, had some mega-million dollar super long lens kit for tracking low altitude rockets etc. Probably not a likely contender for us

(b) Now, I had a couple of high end domestic video units with C-mount demountable lenses. It took about a beer's worth of scribbling on the back of a fag packet to figure that we needed around a 1000mm lens hanging off the C-mount.

So a few calls to the TV stations to find out how they did it. "You want to do 'what'" ? .. back to square one

Eventually, I realised that the race callers must be using something similar to what we needed when they were calling the weekly neddy races in action. A few more phone calls and I tracked down the race video guru. He was doing exactly what I had in mind .. same camera but, admittedly, with much more expensive high end lenses of much lower focal length than I needed. But at least, now, I knew that the idea would work ... (?)

A few sideline tech issues to sort out and we had ourselves a very workable (and dirt cheap) bit of kit. The video output quality at this sort of focal length due to camera/lens mismatch was dreadful .. but it was fine and fit for purpose

The aforementioned zzuf had all the fun in the sharp end for each bird processed.

Thanks for the link to the Boeing presentation ...
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