Originally Posted by Vanel

Quote:

"The altimeters aren't ideal, because certain types of model rockets can't readily carry them without modification, such as punching an atmospheric pressure equalization hole in the payload section tube--if there is one--or perhaps somewhere in the body tube, and some models--such as small boost-gliders and rocket gliders, featherweight and tumble recovery rockets, scale models, etc.--can't carry them at all. Also, the hole's position (with respect to the altimeter), size, shape, and aerodynamic smoothness will affect an altimeter's operation (a messily-punched hole will have rough edges that cause eddies in the incoming or outgoing airflow, which would affect the altimeter's perceived ambient air pressure [and/or delay its ability to register the correct altitude; in very short flights, it could prevent correct altitudes from being registered]). As well:

Altimeters teach relatively little; the student or youth group member pushes a button or two, then sees a number on the altimeter's LED or LCD display after the flight. The altimeter instructions can explain how they work, but it's like looking at an already-worked-out graph of a function. This isn't entirely without educational value, but its effectiveness (and the extent of what it can teach) pales beside the hands-on altitude tracking using theodolite or sighter devices, especially ones built and used by the kids, with guidance from an adult instructor. Doing it that way teaches tool-using skills, geometry, trigonometry, and data reduction. For contest purposes in such activities, altimeters are worthwhile as back-up altitude determination devices (with optical trackers being the primary system), and the models can be selected beforehand to be ones that are compatible with the altimeters."

Your opinion - altimeters are fantastic for showing how pressure, temperature, etc. are related, not to mention the U.S. Standard Atmosphere and so on. Do they teach trig? No. But a good teacher/mentor can use them to teach a bunch of stuff. Plus you are ignoring the value in teaching someone to design/construct an altimeter, which is far more appealing to students these days. Constructing an actual instrument is cool. My club has a 12 year old with an altimeter project and it is amazing at how much he is learning.

In hobby rocketry, the age of the altimeter is here, for better or worse. The numerous "track loss" along with the pain of setting up tracking stations and manning them with people with decent eyes more than mitigate the deficiencies of altimeter use. Using the old style way of tracking is very frustrating for students - I know it was for my long ago mentees when they tried to measure the altitude achieved by their rocket. Even with tracking smoke to mark ejection, they couldn't get a track to close.

Have you ever worked with students using old school tracking, Blackshire?

Originally Posted by Gus

Many NAR chapter heads, like myself, are debating what to do with our theodilites. We feel guilty just throwing them away but are tired of storing the boxes that realistically won't ever be opened again.

Originally Posted by Gus

The Estes Altitrak is useful for teaching the concepts of geometric tracking.


But contest theodolite tracking has rightfully disappeared because it is far too cumbersome to use and has been superseded by very easy to use far better and far more informative technology.


The last NAR theodolite altitude record was set 5/19/12, over 10 years ago.

Many NAR chapter heads, like myself, are debating what to do with our theodolites. We feel guilty just throwing them away but are tired of storing the boxes that realistically won't ever be opened again.

Originally Posted by bernomatic

Actually, before I became entangled in being back to my land surveying job, I was working on a new concept tracking scope over at the Starport Sagitta. tracking theodolite

It used an inclinometer and a holographic site which would have made it a bit more user friendly (read better suited for youngsters). I Never did finish assembling the unit or checking it for accuracy and had not found a suitable horizontal circle to measure azimuths.

As was mentioned in the thread and by Blackshire above, there are issues with the use of a barometer for altitude measurement. Not least of which is the added weight of the unit itself.

One last thing, the "theodolites" of today (actually called total stations) are actually robotic and able to track targets. I have not been in the field with one in a long time and don't know there full potential, but they can also use reflectorless EDM's (Electronic Distance Measurement) to get distances. Given some initial backsites and distances, they will automatically output a height ob their screen. you could also have the information stored automatically in a data collector to be dumped into a computer program. That data can then be imported into a file which is then joined with Google Earth to show in 3D where the points were.

IOW, The good ole Jacob's Staff has evolved from the days of our forefathers. To think that just because a "theodolite" was used back in the day is to think that altitude reading barometers should just be some numbers on a clinky old dial.

Originally Posted by Winston2021

The payload weighs 11 grams... and the FAA and other aviation authorities disagree that it's a hazard... and the thousands of weather balloons launched every year with much heavier payloads have caused no issues... and the sky is a VAST space where, as can be seen in the huge FAA database on aircraft incidents, BIRDS are THE problem for manned aircraft.