Help - Launching a rocket from a weather balloon

[joco28]

I am new to this forum and relatively new to rocketry and I do not want to open up the Rockoon issues again, but I am hoping for some help. I have launched numerous commercial rockets, but now I am biting off a big project. I am in a Science Research class in my high school. I spent last summer completing research in the magnetic fields of low mass stars. For this summer I wanted to do an engineering project, particularly since Covid has stopped so much lab research.

My goal is to launch a (small) model rocket from a weather balloon at 10k, (maybe) 15km and (maybe) 20km, track the flight performance, compare it to the same rocket from the ground, etc. The general idea is to support the use of high altitude launches for small payloads. I know that there had been successful launches such as this before, such as https://news.stanford.edu/2015/02/01/launching-rocket-high-altitude-balloon/, but I believe that my project/research can still add to the field.

I can really use help from people skilled and experienced in model rocketry. I know there are a host of problems to solve, but I am worried about the problems I am not anticipating due to my lack of knowledge and experience. I expect to use a very simple commercial or 3D printed rocket with a mid-power, composite engine.

Among the problems I have identified that need to be solved (any advice would be great):

1) I need a lightweight launch platform that can be taken up by a weather balloon. Since I am currently expecting to use a single balloon, the launch would have to be done at a 15 degree angle to miss the balloon. I have thought about 3 balloons carrying up the platform, but that is expensive and adds even more complexity.
2) an ignition system that will remotely launch the rocket if it reaches an exact height (or "simply" on a timer) and is in the "green" (e.g. the rocket is pointed correctly, any other conditions)
3) a flight control strategy/system. With the extremely low air pressure I am worried that the rocket will not fly on the correct trajectory. A rocket with fins designed for a stable flight from the ground may not work with 90%+ less air pressure
4) effective tracking of altitude, speed, etc. at a much higher altitude than typical
5) are there conditions (temperature, air pressure, oxygen amount) that preclude the ignition and operation of composite engines

I have a number of ideas for the above problems that need to be thought through and tested, but I am most concerned with the problems I do not know. I am sure there is a lot I have not thought of.

Any help would be appreciated. Also, I would be happy if anyone wants to join me in figuring this all out.

Thanks!

 

[dhbarr]

If you haven't successfully launched & recovered either rockets or balloons, it's inadvisable to begin with both at once.

RE: missing the balloon, just launch from the end of a balanced arm.

 

[joco28]

Thank you. Very helpful - balanced arm.

I also appreciate the advice. I have launched rockets a number of times, but only small commercial ones and was part of a school group that launched a weather balloon 2 years ago. That said, this I have a lot to learn and do over the next 3 months. Thanks!

 

[les]

Search for Rockoon. There are many threads here on them plus you may find more info on the web.

Item 3 is a definite concern....

However, if you are trying to fly in the US, from what I've heard the FAA has never approved such an endever.