To view the final, contest entry, see L.A.R.S. on the Instructables web site. Also, be sure to check out the other great entries of the Reuse 2019 contest.
This project is made up of various models and assemblies. All together, they represent a recovery system suitable for a low-altitude water rocket. The rocket is made up of several sections, fabricated from 1.5 liter SmartWater bottles.
The entire system is comprised of several elements within three, primary components:
- Launch Pad
- Propulsion
- Recovery System
The inspiration for this project (as most of my projects) originated with my nephews. Long story short, years ago (when my young nephews weren't so big) they wanted to set off some fireworks on Independence Day. Normally, not so bad, but that year was different: we were planning a long weekend at their grandparent's cabin, in McCall, Idaho. If you've never been to Idaho, it's very dry. If you've never been to McCall, Idaho: it's very dry and there is a LOT of trees, shrubs, grass and other fuels perfect for forest fires. As it was already an incredibly dry year and Smokey the Bear was holding the "HIGH" fire risk sign outside the forest service office, I sought an alternative.
At the same time, I saw it as an opportunity to demonstrate what I try to impress upon young, scientific minds: STAND OUT. Think outside the box and come up with the solution to multiple problems. It may stand out like a sore thumb (bwah!) at first, but the best ideas usually do.
Also, as it turns out, I'm SUPER cheap. Not so much for saving money, but I just see so much that can be done with ordinary things. Most of the time, ordinary things that are meant to be single use.
I would be remiss if I didn't mention this first; I am constantly reminding my nephews "Safety, first." This fits into the overall goal since the primary propulsion is water and air. Obviously, this doesn't pose any serious fire danger.
As I built more sections of the propulsion system, this added volume for more highly-compressed air (i.e. more propellant). Of course, this is directly proportional to the max altitude attainable. Continuing with this logic a bit further: yes, this meant A MUCH MORE DANGEROUS velocity when returning to earth.
The realization of how dangerous this could be became apparent after we had our first successful launch of an early prototype, using multiple sections in the fuselage. Take a look at Rocket Boys, on YouTube.
Minimizing the cost of any build is important. In my scenario, I thought it was equally important to ensure the cost of each use was minimal. I mean, c'mon - who wants to put in a ton of work for a one-time use system?
Anywhere possible, I used junk: water bottles that would go to the trash, an old flight case from the army surplus store, a broken chair umbrella from a local sporting goods store, a burst air hose from Harbor Freight and even a broken, pop-up sprinkler head - basically, I like to teach the kids there's no such thing as trash; it's a product that needs repurposing.
In many cases, things you want to use are not necessarily "for sale" and, if they are, may not be worth their price. The original, green umbrella I used for the parachute was on a broken $28 item at a store. I took it to the counter and said I'd give them the $4 I had on me. I showed them it was broken anyway and explained I only wanted the umbrella material. Voila! we instantly had a parachute.
It's nearly impossible to talk about keeping material cost down without also considering how the product design lends itself to reusability. If we could not easily use the rocket over and over again, we may as well be setting the forest on fire with bottle rockets and M-80s.
After only 1 test launch of our first prototype, I realized the entire rocket system needed to be as compact as possible. At the same time, I wanted to loan it out to anyone who wanted to try it. I didn't want to write a bunch of detailed assembly instructions or rent a moving van for transport.
In the end, I used the box where I stored all the parts as the launch pad. A few modifications made it possible to attach air compressor fittings, hose and no-return valve while leaving plenty of room inside for all sections of the rocket propulsion/recovery systems.
...of course, after the most recent launch, I realized the entire system could stand to be more portable, ha.