Making a non-electronic homemade recovery/ parachute deployment system

Two of my friends and I are making various homemade rocket engines for our school science fair (using a store bought model rocket body), and since the parachute systems for regular model rockets are part of the engine, we were wondering if anyone had any homemade parachute delivery systems, or an alternative recovery system. Of course, we will reference you and give you credit for your design as well. Thanks!

You could look at the problem this way: if your recovery is inside your rocket, you have to force your rocket to separate somehow. Currently a popular way of doing that is pressurizing the parachute bay with exploding gases (black powder) or cool CO2. This must be done at a very specific time, so you could use a timer (electronic or motor delay+charge) or an electronic sensor. It seems you want to find a solution that is 1) not integrated into the motor and 2) not electronically detected. If you want to use a mechanical device, first think about the conditions/state (altitude, velocity, acceleration, orientation, pressure, magnetic field, past states, etc.) of the point at which you want to eject, during the flight, on the pad, and during assembly. Determine how your ejection state is unique from any other state (you wouldn't want to eject in any other state). Once you have this problem figured out, you can start coming up with devices that will only work in a single state.

Okay- I'm gonna get flamed for this, but I'll ignore the 'homemade rocket motor" part first and get to the recovery system. Get familiar with a sim program-Open Rocket is free and damn good. Then run sims for flight times after you've extensively tested your 'home made' motor (it's how it's done in real life-like science) THEN you could conceivably use what is called a 'Tomy Timer'-guts from a kid's wind up toy used for water rockets. Google 'water rockets'. XCheep and a little kludgy unless you go to a "real" electronic based deploy system. Mouse around here in the recovery section for ideas. If you are clever and know how to modify a digital timer, please do NOT post it here! The "parachute system" is NOT part of the rocket motor-that is just the ejection charge. You can incorporate that into your homemade motor. If you are really serious and want to learn "science"-visit Richard Nakka's website. Be safe, wear protective gear and learn a lot. Straight smoke and good chutes!

I dont think I want credit for this one.

Swartz55 said:

Two of my friends and I are making various homemade rocket engines for our school science fair (using a store bought model rocket body), and since the parachute systems for regular model rockets are part of the engine, we were wondering if anyone had any homemade parachute delivery systems, or an alternative recovery system. Of course, we will reference you and give you credit for your design as well. Thanks!

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I don't want to be a spoilsport, but what you're proposing to do for a school project is likely to get you in big trouble as it is illegal for a minor to make rocket motors. If you enter your school with "homemade" explosives, you are likely to be in a heap of trouble. I would discuss this with the school administrators before you go any further because getting arrested is not something you want on your academic record........

Bob Krech, TRF Moderator

Yes and there is a lot of stupid people on you tube . Look around

bobkrech said:

I don't want to be a spoilsport, but what you're proposing to do for a school project is likely to get you in big trouble as it is illegal for a minor to make rocket motors. If you enter your school with "homemade" explosives, you are likely to be in a heap of trouble. I would discuss this with the school administrators before you go any further because getting arrested is not something you want on your academic record........

Bob Krech, TRF Moderator

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I see what you mean. We wouldn't be bringing the fuels into the school, and we'll be supervised by my science teacher who is also a professor and was training to be an astronaut at one point. Plus, my friend is 18, and we could have our parents or my teacher mix it too. But thank you for the warning!

So I guess the moral of the story here is that there really aren't a lot of "standard" homemade deployment systems? I looked at Richard Nakka's website and it did help. We were thinking about using rubber bands and springs to launch the parachute or something.

P.S. I'll still probably discuss this more with my science teacher to make sure we don't get in trouble.

One afternote--don't get discouraged by the limitations of what you can or should do. There are lots of great opportunities in rocketry for trying new concepts and teaching yourself something cutting edge. Obviously, everyone here has your best interests in mind, but the concepts you are exploring and the questions you are asking are indicative of your great potential in science and engineering. We need scientists and engineers, but we especially need good ones--ones who are intellectually curious and ones who don't stop at the status quo. Keep up the good work and keep asking the good questions. Just because you can't do something right now doesn't mean you won't be able to in the future.

I've wondered if something like this is deterministic enough to be used as a simple, mechanical delay:

https://www.orientaltrading.com/crazy-bird-pop-ups-a2-12_3874.fltr?prodCatId=550220

It's just a combination spring and suction cup. You would have to come up with some way of holding it completely compressed until the rocket was launched.

g zilla said:

I dont think I want credit for this one.

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ROTFLMAO!!!

Check out "Rocket Manual for Amateurs" by Bertrand Brinley. It's an old (1960) book that is available online in PDF.

jmattingly13 said:

We need scientists and engineers, but we especially need good ones--ones who are intellectually curious and ones who don't stop at the status quo. Keep up the good work and keep asking the good questions. Just because you can't do something right now doesn't mean you won't be able to in the future.

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We need them with all of their fingers, eyes, brains, etc. Safety is not third, it's first.

mikemech said:

Check out "Rocket Manual for Amateurs" by Bertrand Brinley. It's an old (1960) book that is available online in PDF.
We need them with all of their fingers, eyes, brains, etc. Safety is not third, it's first.

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Good thing I wasn't suggesting to ignore safety. Intellectual curiosity refers to asking questions and exploring concepts, not necessarily conducting dangerous experiments.