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Hello from the New York Spaceport


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Hello everyone!

 

We're a small group of science enthusiasts with varied interests who got together a little over a decade ago after seeing a video about the (then) world altitude record for Water Rockets. Everyone here surely remembers fondly the small plastic rockets that you filled with water and pumped with compressed air and can shoot up 50 feet or so? Well, there exists a small niche of rocketry enthusiasts who design and build their own high performance versions of these rockets that can fly hundreds or thousands of feet in the air. With their short but powerful boost phase, water rockets are ideal for lofting experiments and payloads that commonly available pyrotechnic rockets simply cannot budge.

 

The primary benefit to these rockets is that they don't use combustion to fly and don't use pyrotechnics in their recovery systems, so they are not heavily regulated and are vastly less expensive to build and fly.  Water Rocketry attracts a wide range of people with different backgrounds from all over the world. Given that water rockets are assembled from common everyday materials, the cost to get started is minimal, and this is very appealing to those of us who are on a budget.

 

How this relates to the MSP430 is where things get interesting...

 

A few years ago, Mythbusters did a segment about water rockets, which created a surge of interest in the sport. The surge in popularity generated a lot of wonderful research into improvements in key areas. Enthusiasts began lofting cameras and science experiments and often crashing them, since the state of the art at that time were notoriously unreliable passive and clockwork parachute deploy systems. To improve the reliability of deploy systems, a number of people turned to electronic systems, usually activating a servo motor or a magnetic release. Many designs were built and tested, and at the time there were numerous designs based on the Microchip PIC processors, which we felt were abhorrent even back then. We did some designs based on Motorola micros and some AVR designs, and then we discovered the low cost R/F development kits for the MSP430 and discovered how amazing this family of micros is. We designed a number of deploy controllers and camera controllers and other payloads for our rockets based on the EZ430-RF2500 kits.

 

Around this time, a couple of garage shops took the best designs that were being discussed online, and they rehashed them and started producing and selling various microcontroller servo deploy timers for water rockets. Being early into a new market, quite a bit of price gouging began taking place. This type of thing flies in the face of what water rockets is all about, so we thought it would be great to publish plans on how to build a version of our servo deploy timer. As luck would have it, the MSP430 LaunchPad had just arrived on the market and so a little software work to fit our code into the small memory of the MSP430G2231 was all it would take to make our design work for everyone (Documenting the build process for the average layperson was by far the hardest part of the project).

 

When the project was complete, we published the executable and build instructions, and thanks for the $4.30 price, people could have a servo parachute recovery system for about 10% of the price of the PIC based semi commercial offerings.

 

We absolutely fell in love with the LaunchPad and the fact that it could be programmed easily in C or assembler, and has such a wide range of offerings.

 

Since then, TI upgraded the LaunchPad to the MSPP430G2553, with more memory, and we decided to produce a much more advanced design. With the addition of a Sparkfun barometric sensor breakout board and a piezo buzzer, we created a LaunchPad based model rocket Altimeter with automatic parachute deploy at apogee. This past summer we published the executable and the instructions for this new version and it has been well received.

 

That's our history in a nutshell.  We hope to continue to refine and improve our DIY designs using some of the new LaunchPads which have come out recently. They come out so fast now we have a backlog of ideas to apply! This is a good problem to have!  We hope you enjoyed our story, and look forward to interacting with everyone here on the forum!

 

USWaterRockets

www.uswaterrockets.com

 

 

 

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Hello everyone!

 

Since then, TI upgraded the LaunchPad to the MSPP430G2553, with more memory, and we decided to produce a much more advanced design. With the addition of a Sparkfun barometric sensor breakout board and a piezo buzzer, we created a LaunchPad based model rocket Altimeter with automatic parachute deploy at apogee. This past summer we published the executable and the instructions for this new version and it has been well received.

 

That's our history in a nutshell.  We hope to continue to refine and improve our DIY designs using some of the new LaunchPads which have come out recently. They come out so fast now we have a backlog of ideas to apply! This is a good problem to have!  We hope you enjoyed our story, and look forward to interacting with everyone here on the forum!

 

USWaterRockets

www.uswaterrockets.com

@@USWaterRockets, Welcome! We are happy to have you here and awesome intro!

 

Make sure you put your website in your signature.

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Bluehash: Thanks for the welcome! I didn't want to hotlink to our site or videos showing our project because I'm new here and didn't want to do that until I got familiar with the rules of the forum and what other people were up to. I will put the link in my sig for now. Anyone interested can find the stuff on our website. Thanks again!

 

P.S. Quoting messages does not seem to work for me. Do I need to set something to get that working?

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Zeke: Thanks for the feedback on the tutorials. We have a lot of fun making them.

 

Yes, we've played around with accelerometers and they do work as you suggest, but we found a few drawbacks. The first was the price was quite a bit higher than that of a decent pressure sensor. This may have changed in the past couple of years, but when we were deciding how to improve our deploy detection that was the case.

 

The second drawback is that we realized after we started work on the altimeter that we could optimize the snot out of the code and get it to fit in the MSP430G2231. A lot of folks already made our parachute timer device using the original Launchpad, and we thought it would be great to get the code small enough to fit into the 2K part, so people who already made our timer could convert it to an altimeter with just the pressure sensor. The drawback of the accelerometer is simply that the math is quite a bit more intensive and so the code got too big to fit the 2231. 

 

Also, people who fly water rockets tend to have a lot of variables the things that they can tweak to increase altitude. Changing the nozzle size or the pressure can make a huge difference in altitude. The most important thing we could offer in addition to reliable deploy is a very accurate altitude readout. We found that the pressure altitude reading was more reliable than one calculated from an accelerometer (This improves with higher sampling rates that we couldn't sustain reliably). Water rockets tend to accelerate very rapidly (Think of an airsoft gun), so you need a very high sample rate to get good resolution on the acceleration data to figure out the altitude from acceleration. Being that the altitude readout is an important feature to the end user, we really needed to use the pressure sensor method. We've been told our altimeter is going to be used in school competitions, so we're happy we went this route.

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