Originally posted by ResearchWorm
If I remember correctly, this was/is Estes amazingly expensive hand-held and incredibly inaccurate blue plastic tracking theolodite (I think I spelled that right), and was pretty much useless at altitudes over 400 ft. It was essentially a upside down protractor, a weighted pendellum and a trigger. You'd crosshair the rocket up till apogee, and either release or hold the trigger at that point, read the inclination off the protractor face, and multiply that number times distance to the pad. I think the actual calculation is: Tangent of the angle multiplied by the distance to pad = altitude. If I need to use trig, I have to look up the equations. Only problem was that the numbers were so widely spaced that you'd end up trying to split hairs to figure out what it actually read. It'd probably be easier to make a suitable replacement then to find one. I've seen them at a local hobby shop though (Eagles Games, Models and Miniatures in Bellingham, WA) last time I was home, so I think they are still in production.
A couple of reasonable quality drafting protractors, a plumb bob, a length of wood, two small eyebolts, and a calculator. Cheaper, more accurate, and more educational as well.
Harm none,
RW: I'll have correct you on this one. the alti-Tracks are crude but work quite well a part of a triple tracking station system.. Scout troops up and down the east coast have successfully used this system many times to track and close A- D powered models With closure rates below the magic 10% rate allowed in NAR competition. It's more a product of HOW the trackers are used and on what baseline. Set on a 1000 foot baseline we've had no trouble closing tracks on D powered models in the 2000 foot range. varified by higher tech Theodolites set at the same stations. True a single used for 400feet is pretty useless but set up properly they are an enexpensive way to track model rockets.
ResearchWorm
