A different question

[wesleyw]

Okay we have a Combined Cadet Force at the school which has approx. 50% of the pupils as members. One of them came to me today saying that they release rockets powered by C4 and wondered if I had any device that would be able to give them the height the rocket got to?


Any ideas guys?



Wes

[strawberry]

string ?

[kennysarmy]

@strawberry lol

thanks for making me chuckle today

[somabc]

An Altimeter

Rocket Altimeter

Altimeter: SEAM calculations to determine the altitude of your rocket

[wesleyw]

Thanks I'll go have a look.

[strawberry]

@strawberry lol

thanks for making me chuckle today

was a serious answer!, if you tie string to the rocket and coil it up whatevers uncoiled will be how far it went!.

[SYNACK]

Maths and a stop watch, all you need to do is start timeing when it reaches its maximum height then stop when it hist the ground, you know that acceleration due to gravity is 9.8m/s so you can work out the height that it fell from.

WikiAnswers - How do you find the maximum height and time of flight for the rocket in question 32

You can also use trig to measure irs apparent angle at the top of its flight path:
Ptolemys' Ptools - Measuring the Height of a Model Rocket's Flight

Or there is some software that says it will do it from here:
SpaceCAD Model Rocket Software



If you are specifically after a device you can use a magnetic apogee detection sensor to determin the height by changes in the earth magnetic field or build/buy a small altimeter, you should be able to find sources to both from here:
Model rocket payloads

there are other specs to build one from here:
Rocket Altimeter Project (RAP)

On a side note are you sure that they are using C4 to fuel the rockets as I was sure that that was a military/commersial grade explosive that would be far more likely to accelerate the rocket in all directions at once than polightly heft it skyward

[SteveLaw]

C4?

[kennysarmy]

was a serious answer!, if you tie string to the rocket and coil it up whatevers uncoiled will be how far it went!.

I know !!!!!!

it just made me chuckle thinking that the OP wanted some high-tech answer and sometimes the most elegant solution is the simplest

[powdarrmonkey]

Can you guarantee that the rocket flies directly upwards though? Otherwise you'd have to measure the distance to its landing point and triangulate.

[CHR1S]

Perhaps using a theodolite? Theodolite - Wikipedia, the free encyclopedia