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  • How to build
    your own
    Water Rocket
    • Water Rocket Tutorial Index
    • Water Rocket Construction
      • Parachute

        A strong and reliable parachute design is very important to anyone wishing to develop a water rocket with a recovery system. Any system from a simple Air Flap mechanism to the sophisticated ServoChron™ electronic deploy system relies on a well made parachute. This tutorial will reveal the secrets to easily making a parachute that will safely recover your water rockets.

      • Bottle Coupler

        This tutorial will show a method for creating inter-bottle connectors which can be used to join together multiple bottles by the threaded necks. These bottle connectors are useful for Water Rockets because they allow for a modular approach to be applied to your rocket design, which simplifies construction and repair of a damaged rocket.

      • Bottle Cutting

        Nearly every water rocket design that you can construct will involve some sort of bottle cutting. This tutorial will show you an easy method for getting perfect cuts every time.

      • Constructing Removable Box Fins

        One set of Water Rocket components which are critical to a successful and stable flight are the fins. U.S. Water Rockets designed and tested a new idea for creating water rocket fins which is called the "Box Fin" design, to create a quick and easy method for adding fins to Water Rockets which were much more rugged than typical fins, yet easier to fabricate with a higher degree of accuracy. This tutorial will explain how to create a triple box fin for a water rocket.

      • Enhancing Removable Box Fins

        The first improvement we will make is to modify the fin design so that it is adjustable to fit multiple bottle diameters. The next improvement we will make is to alter the attachment method for the fins. If you fly in an area prone to landing in trees, you can modify the design so that it will break away from the rocket with less force.

      • Nosecone

        One of the most important components you will build for your water rocket is the nosecone. This tutorial will explain how to build a good looking nosecone that performs great too.

      • Corriflute Recycling

        A relatively new building material used in the construction of water rockets is a corrugated plastic sheet or corriboard. It is also known under the tradenames of Corriflute, Coroplast, IntePro, Correx, Twinplast, or Corflute. This tutorial explains how to repurpose used corriflute for your water rockets.

      • Bottle Label Removal

        This tutorial will show you how to prepare your bottles for Water Rocket Construction. To prepare your bottles, the labels and glue must be removed, and the bottles must be cleaned of all contamination from their contents and oils left from manufacturing or handling.

      • Bottle Label Removal V2

        This tutorial will show you another method how to prepare your bottles for Water Rocket Constrction. This involves removing the labels and adhesive from the bottles and making sure there are no oils on the bottle. Failing to do so can result in the rocket leaking or exploding under pressure, due to contaminated splices.

    • Launchers
      • Cable Tie Launcher

        What good is building a water rocket if you have no way to launch it? The launcher we will be constructing is a variation of the Clark Cable Tie launcher, as this is the most reliable launcher that is easy to make.

      • Launch Tube o-ring

        Revised instructions for adding the o-ring to the Clark Cable Tie Launcher launch tube which simplify the build and improve the design. We have put a lot of effort into simplifying the design to remove steps which involve precise measurements and part placement, to maximize the ease of construction.

      • Cable Tie Release Mechanism

        This tutorial shows how to add a Clark Cable Tie Release Mechanism to the 22mm Launch Tube fabricated in the previous tutorial. This tutorial shows the newly revised and simplified instructions for making the release.

      • Split Collar Launcher

        This tutorial shows how to create the latest type of water rocket launcher which uses the newest improvements.

      • Gardena Launcher

        This quick tutorial showing how to make a compatible water rocket launcher that uses a gardena hose quick release connector for the release mechanism. This type of launcher also works with any standard gardena nozzle in addition to our 3D printed nozzle design. If you have all the materials on hand you should be able to build this launcher in an hour or less and be out launching water rockets in no time!

    • Parachute Deployment Mechanisms
      • ServoChron™ Quick Start Guide

        The ServoChron™ is a low cost time delayed dual servo controller designed for use as a parachute deployment or staging mechanism for Water Rockets. There are other potential applications for the ServoChron™ as well. The core of the ServoChron™ is the Texas Instruments MSP430 LaunchPad. This $4.30US board is an inexpensive microcontroller hobbyist experimenting platform that you load our FREE application firmware into with a USB cable. The FREE ServoChron™ application firmware file created by U.S. Water Rockets turns the MSP430 LaunchPad into a user programmable dual servo deployment system timer/controller.

      • Launch Detect Switch

        This tutorial will show you have to construct a very reliable and lightweight acceleration switch which you can use to activate electronic systems on your rocket such as a ServoChron™ 2 Dual Servo Actuated Parachute Recovery System.

      • Parachute

        A strong and reliable parachute design is very important to anyone wishing to develop a water rocket with a recovery system. Any system from a simple Air Flap mechanism to the sophisticated ServoChron™ electronic deploy system relies on a well made parachute. This tutorial will reveal the secrets to easily making a parachute that will safely recover your water rockets.

      • Radial Deploy System

        Since it is the key to safely recovering a rocket and payload and all the time, materials, and labor that went into building them To insure the safe recovery of our fragile and expensive experiments and payloads, we decided that we needed to invent a parachute system that was more reliable than anything ever flown before. We dubbed this new design the "USWR Radial Parachute Deployment System", and it is a radical departure from traditional systems, because it relies on only one moving part. The system we designed met that goal and also has a number of other advantages over previous systems.This system is less expensive and time conuming to build, has less moving parts, and can be located more places on your rocket.

      • Axial Deploy

        The objective of this tutorial is to demonstrate how to build a completely new type of parachute recovery system for water rockets. This system was developed to fill the need for a reliable parachute recovery system that could be made from common materials which was very easy and fast to make. Historically, ease of assembly and reliability have been mutually exclusive goals. This prompted U.S. Water Rockets to take a "clean slate" approach to the problem. This tutorial will explain how to construct the latest version of the U.S. Water Rockets Axial Parachute Recovery System.

      • Hybrid Deploy

        The Hybrid Deploy System is our latest idea for improving water rocket systems to make them more reliable and easier to build. This system improves upon our previously published designs known as the Axial Deploy System, and Radial Deploy System. By combining the ease of construction of the Radial Deploy System, with the heavy duty capacity of the Axial Deploy System.

      • Launch Detect Switch

        This tutorial will show you have to construct a very reliable and lightweight acceleration switch which you can use to activate electronic systems on your rocket such as a ServoChron™ Single/Dual Servo Actuated Parachute Recovery System.

    • Splicing
      • Bottle Splicing

        In order to create larger Water Rockets with bigger pressure chambers than afforded by typical soft drink bottles, many enthusiasts have resorted to joining multiple bottles together using various methods which all are commonly referred to as "splicing". This tutorial will show you how to use this new method to create perfect splices that are easier to create and outperform traditional splices in both strength and appearance.

      • Bottle Label Removal

        This tutorial will show you how to prepare your bottles for Water Rocket Construction. To prepare your bottles, the labels and glue must be removed, and the bottles must be cleaned of all contamination from their contents and oils left from manufacturing or handling.

      • Bottle Cutting

        Nearly every water rocket design that you can construct will involve some sort of bottle cutting. This tutorial will show you an easy method for getting perfect cuts every time.

      • Tornado Tube Coupler

        Many teams build their rockets in this manner using a pre-manufactured commercial product used in school science experiments commonly called a "Tornado Tube" or a "Vortex Bottle Connector". The commercial versions typically cost $1.00US to $2.00US each. This tutorial will show how to make them for pennies each and without the expense and time consuming process of turning them on a lathe. This method could also be applied to other size bottles such as the wide mouth bottles that sports drinks often are supplied in. These bottle connectors are useful for Water Rockets because they allow for a modular approach to be applied to your rocket design.

    • Creating Panoramas

      This tutorial explains how to create a panoramic view using some free image stitching software which you may already have on your computer and were not even aware of!

    • Tree Recovery System

      If you have hobbies which involve things that fly such as RC Planes, Drones or Model Rockets, then chances are that you've had one which you were flying end up stuck in a tree. We've had this experience a number of times in the past, and we wanted to share our Tree Recovery System with you so that you may benefit from our design. In this Tutorial we will show you how to build and how to use our design, which is easy and inexpensive to make and works amazingly well.

  • World Records
    • World Record Index
    • 2004
      • September 2, 2004 1,421 feet

        On September 2, 2004 U.S. Water Rockets set a new single stage water rocket altitude record with an average altitude of 1,421 feet, beating the old record of 1,242 feet that was held by Anti-Gravity Research.

      • September 6, 2004 1,471 feet

        Just 4 days after setting the water rocket single stage world record, it was raised to 1,471 feet.

      • September 11, 2004 1,481 feet

        After 4 more days X-10 set a new water rocket altitude record of 1,481 feet

      • October 23, 2004 1,606 feet

        On a beautiful fall day with the autumn foliage in full glory, the water rocket altitude was raised to 1,606 feet (stunning autumn foliage can be seen in the onboard videos).

    • 2005
      • April 16, 2005 1,609 feet

        On the first launch day of 2005 a new single stage water rocket altitude record was achieved. The required two flights averaged at 1609 feet.

      • May 26, 2005 1,696 feet

        This record was described on the television show Mythbusters.

      • September 24, 2005 1,715 feet

        The shakedown flights for the new X-12 water rocket proved to be winners with a new world record of 1,715 feet.

    • 2006
      • April 29, 2006 1,787 feet

        The freshly rebuilt X-12 water rocket sets a new world record after nearly being destroyed in an October 2005 crash during a record attempt.

      • April 30, 2006 1,818 feet

        After setting a record the day before, the weather conditions were conducive to another record attempt. A new record of 1,818 feet was achieved as the 2 flight average.

      • May 8, 2006 1,909 feet

        On May 8th 2006, a new WRA2 water rocket single stage world record was set by the famous X-12 water rocket.

    • 2007
      • June 14, 2007 2,044 feet

        X-12 pushes the official water rocket single stage world record to over 2,000 feet with an average of 2,044 feet.

  • Launch Reports
    • Launch Reports Index
    • 2004
      • 8-22-2004
        X-10 Crashes

        X-10 Water Rocket crashes and results in the total loss of a video camera and altimeter earlier today during a shakedown flight of a Water Rocket designed to set the World Record for Altitude. The launch went perfectly, but when the rocket went through apogee at nearly 1,200 feet it deployed a parachute which somehow separated from the rocket.

      • 9-12-2004
        Tree Recovery

        A recovery crew for U.S. Water Rockets successfully retrieved the World Record Holding X-10 Water Rocket from a precarious position in a tree, where it had been lodged for 3 weeks. This flight insured the development of our tracking and telemetry system.

      • 11-23-2004
        HD Camera Test

        The successful construction & testing of the remarkable new C-7 payload bay, the first ever payload section to loft a High Definition Water Rocket Video Camera

      • 11-27-2004
        HD Camera Test II

        C-7 is the highest resolution Movie Camera to ever fly aboard a Water Rocket, and was designed to outperform its predecessor, C-6 in resolution and framerate. In the second round of test flights, C-7 performed spectacularly, producing very smooth clear video with every test.

    • 2005
      • 6-5-2005
        Rapid Deploy Parachute

        The latest round of test flights which allowed ground observers to view and photograph a new design parachute in action. The entire deployment process was easily visible with binoculars from the ground, making the performance of the new system easy to evaluate. As a backup, in case the ground observations failed to produce conclusive performance data, we installed an innovative "ChuteCam" system in place of the WRA2 required Apogee camera. The ChuteCam uses a series of prisms to bend light and give the ChuteCam a reverse angle view, perfect for observing the parachute unfurling behind the rocket after deploy.

      • 10-29-2005
        Crash from 1,819 Feet

        While attempting to set a new WRA2 record altitude, parachute failure dooms X-12 and inspires herculean data recovery effort to recover the video from the destroyed camera.

    • 2006
      • 6-6-2006
        2,001 Feet

        Although not an official record due to a second flight did not occur due to lack of daylight, X-12 becomes the first Water Rocket ever to surpass 2,000 feet.

      • 7-19-2006
        2,088 Feet

        X-12 reaches an unprecedented altitude of 2,088 feet (636 m) on a clear summer afternoon with great visibility and bright sunshine. Unfortunately, when the rocket was recovered the water tight bulkhead seals of the payload section appeared to have cracked under the tremendous acceleration of launch and allowed water to fill the electronics bay upon splashdown.

    • 2008
      • 12-26-2008
        Project 3000

        Launch Report of our X-12 Carbon Fiber High Pressure Water Rocket conducted to test our new HD camera and electronics payload during freezing cold weather conditions which resulted in a near disaster when the parachute failed, only to be saved at the last second by a tree.

    • 2011
      • 11-25-2011
        7 Cameras

        Our B-2 Water Rocket was test flown with an unofficial word record of 7 onboard cameras in order to record video of a test of some enhancements to our free ServoChron Servo Deploy Timer Software, and our newly invented Axial Parachute Deploy Recovery Ejection System. This Launch Report contains the details of the launch and the results of the flight, including failure analysis and data logs.

    • 2016
  • Research & Development
    • Research & Development Index
    • Deployment
      Systems
      • Dual Deployment System

        The dual deploy system proved to be a resounding success and a quantum leap in safety. If either one or even both of the parachutes became tangled or failed to inflate, the separate rocket sections would be too unstable to fall ballistically to the ground. Instead, the sections would tumble slowly down, reducing the chance for injury or property damage on the ground due to a "lawn dart".

    • Launch
      Systems
      • Split Collar Launcher

        Water Rocket launcher mechanisms are an important area of Water Rocket design which has received almost no attention by researchers for more than a decade. This Research and Development article introduces our completely new launcher design to the water rocket community, and the history of the evolution of this radical new design.

    • Tracking & Telemetry Systems
      • Ground Test

        A rocketeers worst nightmare is a lost rocket, to combat this we designed our own telemetry and tracking system. A ground test of our new telemetry and tracking system

      • Live Test

        A live test of the tracking system proved a range of 50,000 feet.

    • Tools
      • Bottle Cutting Tool

        The bottle cutting jig will cut a straight cut around your bottles to remove the bottom or neck when splicing or making nosecones.

    • Pressure Tests
      • Compressor Failure

        To construct a world record water rocket, we needed to do many pressure tests. On this test the compressor failed and caught fire. Then the test vessel self launched at 300PSI!

      • Thermal Imaging
        Pressure Test

        Does a water bottle rocket explode because the plastic bottle heats and softens when the air inside is expanding and stretching the plastic? We wanted to find out. The purpose of this experiment is to determine if bottle burst pressure is reduced because of the heat generated by the stretching bottle as it expands.

    • Chase Camera

      As early as 2003, we were experimenting with ways to get outside views of our water rocket. Back then we had been flying a camera inside a payload compartment that was meant to separate from the pressure vessel at apogee. This article shows the development of a new system which would record the entire rocket for the entire flight, rather than just the descent of the pressure vessel.

    • 3D Camera

      At that time, basic ordinary video cameras capable of shooting 3D were quite costly (and they never came down in price since 3D never caught on in a big way). Therefore, we decided the only way to accomplish what we wanted was to build a 3D Camera Rig that would allow us to use our specialized cameras to achieve the goal. The way to accomplished this is to somehow use two similar cameras in tandem to capture photos and videos for each eye, and then merge them in software to create 3D output.

    • Tower Camera

      We wondered what the view would be like to a person standing on the tip of a Water Rocket as it was launched hundreds of feet into the air, so we came up with an idea to make a tower to mount a camera on the top of a Water Rocket, so we could find out what it would look like from that point of view.

  • MSP430 Launchpad Projects &
    Utilities
    • MSP430 LaunchPad Index
    • Projects
      • Replace Male Headers

        This tutorial will show a clever trick which will make it extremely easy for anyone of any skill level to remove the male headers that are installed on the MSP430 LaunchPad without damaging the circuit board, and replace them with the female headers provided.

      • Horizontal Stabilizer

        This tutorial shows how to modify your MSP430 LaunchPad so that you can use it with both Breadboards, and BoosterPacks. This simple modification is very easy and costs almost nothing. You can have the best of both worlds by adding these "Horizontal Stabioizers" to your MSP430 LaunchPad.

      • Ruggedizing the LaunchPad

        This tutorial shows how to modify your MSP430 LaunchPad so that the removable jumpers will not come loose if your MSP430 LaunchPad is subjected to high accelerartion or vibration forces. This simple modification is very easy and costs almost nothing.

    • MSP430 Drivers
      • MSP430 LaunchPad Drivers

        This archive contains the MSP430 Application UART driver file necessary to communicate to the UART on the MSP430 Launchpad. MSP430 projects which communicate to the PC will use this driver.

    • ServoChron™
      • ServoChron™ Manual

        The ServoChron™ is a low cost time delayed single/dual servo controller designed for use as a parachute deployment or staging actuator mechanism for Water Rockets, or Water Rocket Propelled Vehicles. There are other potential applications for the ServoChron™, but this document focuses on the Water Rocket single/dual parachute deploy application. The ServoChron™ was created specifically to make servo controlled recovery and staging mechanisms easy to build, and affordable or everyone. Note: this manual includes the ServoChron assembly, programming and operating manuals into one convenient file. This manual supersedes the previous revisions.

      • ServoChron™ Firmware

        ServoChron™ Firmware file archive for the MSP430 Launchpad.

  • 3d Printing
    • 3d Printing Index
    • Gardena Nozzle

      A type of Water Rocket launcher that has been popular for well over a decade uses a garden hose quick release connector for the launcher mechanism. These connectors are often called Gardena connectors because of a popular brand of connector that these launchers and nozzles were made from. We used a CAD program called Alibre to create the custom nozzle object, and then printed it on a Rostock Max V2 3D Printer. We have also shared the 3D file for this custom 3D nozzle on thingverse.

    • Self Aligning Fin Brackets

      We put our new 3D Printer to use making our fin brackets, but there's no reason something similar could not be made from scratch using fiberglass, plastic, wood, etc. The 3D Printer just makes producing a lot of brackets as easy as pressing a button, walking away, and coming back later to collect the parts. Using this technology also allows us to configure the printer to print the brackets as hollow shapes, meaning that they are very lightweight.

    • Star Wars Droid

      U.S. Water Rockets is proud to release this nearly ¼ Scale accurate droid replica for 3D printing. This replica robot from the Star Wars Universe was designed to be the most detailed and accurate 3D Printable Astromech droid you can print, with exceptional detail lacking in other printable models.

    • Universal Fin Can

      U.S. Water Rockets is proud to take fin construction to the next level, by using 3D printing technology. Our initial effort resulted in a set of fins which are joined together by a cylindrical section that holds them in perfect alignment. This arrangment is commonly referred to as a "Fin Can".

  • Tips to increase performance & Altitude
    • Tips Index
    • Increase Altitude/
      Go Higher
      • Weight Reduction

        A lighter rocket will fly higher. Removing excess weight is one of the simplist ways to make your water rocket fly higher. This tip will show you how to make your water rocket, payload bay, camera, and deployment mechanism lighter.

    • Design
      Competition
      winning
      rocket

      Our team was recently asked to assist some students participating in a water rocket distance competition held by their school. We had never done any experiments in achieving maximum distance, so we were excited by the prospect of applying our experience in setting world records for altitude, as well as the chance to work with students in the STEM field.

  • LaunchPad AlTImeter
  • Manuals & Documentation
    • Manuals & Documents Index
    • Manuals
      • LaunchPad AlTImeter Manual

        Have you ever wanted to use an electronic altimeter to find out how high your rockets fly, but you have found that the commercially available altimeter products are too expensive? U.S. Water Rockets proudly presents the LaunchPad AlTImeter, a very low cost model rocketry peak recording altimeter with optional apogee detect output and servo motor control connection. With this "Do it yourself" project, you can save close to 80% or more of the cost compared to commercially available altimeter systems.

      • LaunchPad AlTImeter Firmware

        LaunchPad_AlTImeter Firmware file archive for the MSP430 Launchpad.

      • ServoChron™ Manual

        The ServoChron™ is a low cost time delayed single/dual servo controller designed for use as a parachute deployment or staging actuator mechanism for Water Rockets, or Water Rocket Propelled Vehicles. Note: this manual includes the ServoChron assembly, programming and operating manuals into one convenient file. This manual supersedes the previous revisions.

      • ServoChron™ Firmware

        ServoChron™ Firmware file archive for the MSP430 Launchpad.

    • Documents
  • Downloads
    • Downloads Index
    • LaunchPad AlTImeter™
    • MSP430 LaunchPad Drivers

      This archive contains the MSP430 Application UART driver file necessary to communicate to the UART on the MSP430 Launchpad. MSP430 projects which communicate to the PC will use this driver.

    • ServoChron™
      • ServoChron™ Manual

        The ServoChron™ is a low cost time delayed single/dual servo controller designed for use as a parachute deployment or staging actuator mechanism for Water Rockets, or Water Rocket Propelled Vehicles. Note: this manual includes the ServoChron assembly, programming and operating manuals into one convenient file. This manual supersedes the previous revisions.

    • MSP430 LaunchPad Drivers

      This archive contains the MSP430 Application UART driver file necessary to communicate to the UART on the MSP430 Launchpad. MSP430 projects which communicate to the PC will use this driver.

    • MD-80 Camera
    • 808 Keychain camera
      • Clock Set Instructions

        Instructions and examples showing how to set the clock in the 808 Car Keys Keychain Type #11 HD720P MiniDV Camera.

      • Datestamp removal

        808 Keychain camera Type #11 Firmware file disabling the timestamp feature. NOTE: This firmware works on all models.

      • Continuous Record

        Version 2 of the 808 Keychain camera Type #11 Firmware file enabling the "continuous recording" feature. This firmware adds the following: a) The camera will not split recordings into 20 minute clips, it breaks recordings up into 4GB segments instead. b) The timestamp is disabled. c) If the battery dies, the last clip is properly saved. NOTE: This firmware works on all models.

    • Downloadable Photo Screensavers

      U.S. Water Rockets has just announced a newly created photo documentary journaling their Experimental Water Rocket Launches in the form of a Microsoft Windows Compatible Screensaver for all PCs. The new screensaver details many of their flights and contains their world famous Fall Foliage Aerial Photos, which were shot in the peak of the leaf season in northern New York State. These Screeensavers are simply loaded with breathtaking views from high altitudes, and ground camera footage from dozens of launches that kids young, old and young at heart will enjoy.

  • Water Rocket Resources
  • About USWR
  • Search
Member of the The Water Rocket Achievement World Record Association   Member since 2003


LaunchPad AlTImeter

The Servo Deploy Model Rocket Altimeter you build yourself!


Have you ever wanted to use an electronic altimeter to find out how high your rockets fly, but you have found that the commercially available altimeter products are too expensive? U.S. Water Rockets proudly presents the LaunchPad AlTImeter, a very low cost model rocketry peak recording altimeter with optional apogee detect output and servo motor control connection. With this "Do it yourself" project, you can save close to 80% or more of the cost compared to commercially available altimeter systems. Anyone can make this project by following the free instructions we provide and the free firmware package available on our USWaterRockets.com website.
We're giving this project to the community for free, to raise awareness of model rocketry to the general public, and to help encourage more friendly competition. This instrument can also be a wonderful learning tool, teaching how to improve the performance of model rockets through real flight data measurements.
We are also planning on getting this design approved for actual rocketry competitions, and wish to work with groups like the WRA2.org and NPL.co.uk to that goal.

Table of contents:

Please click a links below to jump to a section of the documentation. If you are new to barometric altimeters or have only used simple toy altimeters in the past, you should take the time to carefully read the documentation. There are many simple things you can do to improve the accuracy of your altimeter data that are discussed in this documentation.

Introduction:

The LaunchPad AlTImeter is a low cost, high quality "Do It Yourself" model rocket altimeter that has optional parachute deploy outputs which you can easily make yourself for far less cost than commercially available altimeters on the market that have only a fraction of the performance!
Our experience in building word record setting high altitude water rockets using many of the major commercially available altimeter brands has given us the background experience needed to create an altimeter that is uniquely suited for use with all forms of model rockets, including water rockets. The LaunchPad AlTImeter is the first rocket altimeter specifically designed to address the needs of both Pyro and Water Rockets.
The LaunchPad AlTImeter can be assembled as a simple altimeter, or it can be built with an optional servo for parachute recovery. It also has a digital output that signals apogee detect for use with external recovery hardware.

What it does:

The primary function of the LaunchPad AlTImeter is to report how high your model rocket flew. A secondary function allows you to connect optional Servo Motors or Ignition systems to deploy a parachute at apogee. Knowing how high your rocket flew after each flight can help you tune your rockets for better performance, and the ability to trigger a parachute at apogee results in safer and more reliable recovery.

How it works:

LaunchPad AlTImeter is installed in the payload compartment of a model rocket and measures the current altitude of the rocket over 100 times a second. The specialized software running in the onboard MSP430 microcontroller processes any changes in altitude over time to detect key events in the rocket flight where specific actions take place, like detecting the liftoff, or deploying a parachute at apogee.
Altitude is measured with a micromechanical barometric pressure sensor which senses the weight of the atmosphere pressing down from above. The determination of altitude this way is possible because the higher you are in the atmosphere, the less air there is above to press down
The LaunchPad AlTImeter uses the US Standard Atmosphere model 1976 (NASA) to convert the measured pressure into altitude.
[Back to Table of Contents]

Quick Start Guide:

This section will help you resolve the most common problems that people encounter with the LaunchPad AlTImeter.
From time to time you may encounter an issue that you do not understand. Use this troubleshooting guide to help resolve problems.

If you are already familiar with model rocket altimeters, or you are simply an all-knowing genius, you can skip many of the details of this documentation and follow these steps to get up and running fast!
  1. Go right to the Parts List and Assembly Tutorial Sections of this document to build your LaunchPad AlTImeter
  2. If you are using the Parachute Deploy features, read the Parachute Deploy section and User Configuration sections.
  3. Install the LaunchPad AlTImeter in your rocket, leaving a vent hole to allow the outside air pressure to reach the sensor.
  4. Arm the launch detection system by pressing and holding in S2 for 5 seconds, and wait 30 seconds for the arming delay to expire.
  5. You can now launch your rocket.
  6. After landing, you can read out the apogee altitude on the red and green LEDs or listening to the optional buzzer beeping.
The Basic LaunchPad AlTImeter
The Basic LaunchPad AlTImeter

For technical support, please use the LaunchPad AlTImeter technical support forum.
[Back to Table of Contents]

Parts List:

To assemble a LaunchPad AlTImeter, a number of components are required.
Everything you will need to build the Basic Version (No Servo variant).
Everything you will need to build the Basic Version (No Servo variant).
The design has been thoroughly tested using the components listed below. All of these parts for the basic altimeter only model are available from SparkFun Electronics. www.sparkfun.com. You will need a few additional components from HobbyKing www.hobyking.com if you choose to add a servo deploy.

Parts needed for basic Altimeter:

Component Source Part Number
MSP430 LaunchPad estore.ti.com MSP-EXP430G2
Pressure Sensor Breakout SparkFun SEN-11084
9V Battery Connector** SparkFun PRT-00091
9V Battery** SparkFun PRT-10218
Audio Transducer SparkFun COM-07950
**Optional

Optional Parts needed for Servo Deploy:

Component Source Part Number
Mini Plug for Micro Battery HobbyKing HK9727
138mAh Lithium Polymer Cell HobbyKing BAT13810C
HXT900 9g Micro Servo HobbyKing HXT900
Jr-Type Servo Extension Lead** HobbyKing AM1043-10-32
**Optional
[Back to Table of Contents]

Assembly:


Tools Needed to build the LaunchPad AlTImeter:

  • Wire Cutter
  • Wire Stripper
  • Solder
  • Soldering Iron
  • Hobby Knife
Within these assembly instructions, you can click on the photos and illustrations to see them expanded and read additional assembly notes for more information.
Be aware that there are some exceptions to the assembly that you will need to follow if you plan on using a Servo recovery system with the LaunchPad AlTImeter. Exceptions will be clearly marked. If you choose not to use a servo, you can ignore the exceptions.
Note that there are multiple versions of the MSP430 LaunchPad board which have been manufactured over the years, and the instructions will vary slightly from one board version to another. These instructions will note any different procedures you need to follow for different MSP430 LaunchPad versions.

Step 1: Unboxing the Texas Instruments MSP430 LaunchPad Evaluation Kit:

Open up the box containing the Texas Instruments MSP430 LaunchPad Evaluation Kit, and remove the main board and the Mini USB cable. These are the only items in the box which you will need for this project. Save the rest of the parts (especially the spare microcontroller integrated circuit in a safe place, as we have plans for those which you may want to follow in the future.

Step 2: Prepare the Male Header pins used on the MSP430 LaunchPad:

The MSP430 LaunchPad comes with 20 male pins in 2 rows of 10. Older model boards shipped with the pins included in a small package in the box, not installed. Only 6 pins are needed for this project, soldered in connector J1 holes 4 through 9. Clip off or de-solder and remove any unused header pins (or install the required pins, if they were shipped separately in the box).

Step 3: Solder the barometric pressure sensor breakout board to the MSP430 LaunchPad:

You must solder the pressure sensor breakout board to J1 pins 4 to 9 in the position shown in the assembly photos. Make sure that the sensor board is oriented as shown before you solder each pin to the male header pin.
When you have finished soldering the pressure sensor breakout board in place, you can trim off the excess portion of the male header pins protruding through the board.

Step 4: Add jumper wires if you are using the 14-pin MSP430 chip:

Some MSP430 LaunchPads ship with a CPU that has 14 legs, and others ship with a 20 leg chip. If you have a chip with 14 legs, you need to install 2 additional wires. One wire connects pin #8 of J1 header to pin #1 of J1. The second wire connects pin #9 of J1 to the bottom of S2. If you do not have wire on hand, you can take a small portion of the battery lead for this purpose.

Step 5: Solder the battery connector to the locations shown in the accompanying photos.

If you do not plan to use the optional servo deploy, you can use a 9V battery and battery clip. If you are going to add the optional servo deploy, then you should install the Mini Plug for Micro Battery.
Solder the Red and Black wires in the holes as shown. CAUTION: Do not swap the colors in the holes because this will destroy your MSP430 LaunchPad.

Step 6: Solder the audio enunciator to the MSP430 LaunchPad as shown:

If you want audio status sounds from your LaunchPad AlTImeter, you can install the optional audio transducer as illustrated. You will need to bend the pins closer together with a pair of pliers before installing because they are slightly wider than the holes provided. Note that one pin of the Audio Transducer is marked with a "+", and this must go into the hole marked "XOUT".

Step 7: Solder the servo to the MSP430 LaunchPad as shown (Servo Deploy Optional):

If you want to deploy a servo motor operated parachute with the LaunchPad AlTImeter, you can connect an optional servo. You can solder the servo directly to the LaunchPad AlTImeter, or use a JR type extension lead so that you can unplug the servo from the board in the future.
Warning: Do not use the servo motor with the 9V battery power option. You will damage the servo!
To connect the servo, cut the female connector off the end of the servo leads, and solder the brown servo lead to the black battery lead. Solder the red servo lead to the red battery lead, and solder the orange servo lead to P1.7 hole in your MSP430 LaunchPad.
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Programming:


The heart of the LaunchPad AlTImeter is an MSP430G Value Line microcontroller from Texas Instruments. This microcontroller contains flash memory which must be programmed with the LaunchPad AlTImeter software, to create the finished product. Follow the procedure below to load the firmware into the MSP430 LaunchPad:

Programming Step 1: Download LaunchPad AlTImeter firmware project:

Click on the link provided below to download the firmware project file: LPAlt_V100.zip, and save the file on your computer.

Programming Step 2: Extract the firmware file:

Open the file you just downloaded and drag the files into a convenient folder location on your computer.

Programming Step 3: Download the Programming Software Tool:

Go to the website http://www.elprotronic.com/download.html and download the free program called "FETPro430 Lite". When the download has completed, read the installation instructions and follow the procedures for installing the software and the USB drivers included. This is a third party utility and if you have difficulty with this step, you should contact Elprotronic for technical support with their utility.

Programming Step 4: Launch the 3rd party programming utility:

Go to the "File" menu of the FET-Pro430 Lite application and click on "Open Project". You will then be presented with a file open dialog with which you will navigate to the directory where you saved the firmware project file. You select the firmware you wish to load and click "Open". The project file will then load into the programming application.

Programming Step 5: Program the Microcontroller on the MSP430 LaunchPad:

Disconnect any batteries from the LaunchPad, and connect a USB cable from your PC to the USB port on the LaunchPad.
Warning: You must NEVER connect the battery and the USB cable at the same time. You can damage your PC or the LaunchPad, or cause the battery to explode.
Once you have connected the USB cable you can press the "AUTO PROG." button to load the firmware file.
Exceptions:
If your MSP430 LaunchPad is Version 1.5 or newer, it most likely has a microcontroller with a different part number installed on the board. The programming software will detect this different part and ask that you confirm the download is correct. Click on the confirmation 'Yes' button to proceed.
The programming tool will report "PASS" when the operation is complete.

Programming Step 6: Finishing:

Congratulations! Your LaunchPad AlTImeter is ready for flight! Close the programming software and disconnect the USB cable from your computer. You are now ready to use your LaunchPad AlTImeter.

You should now carefully read the installation guide section to learn the proper way to install the LaunchPad AlTImeter in your rocket. Improper installation can result in poor accuracy or even damage to the LaunchPad AlTImeter.
If you want to add a Parachute Deploy system to your LaunchPad AlTImeter, please consult the Parachute Recovery section before continuing.
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Installation Guide:

You will be installing the LaunchPad AlTImeter inside your rocket prior to launch so that it is carried with your rocket to measure the altitude. It can be oriented in any direction in any position that is convenient. More accurate readings will be recorded if the LaunchPad AlTImeter is secured to a bulkhead so that it does not shift around or get bumped during flight. We suggest affixing the LaunchPad AlTImeter to a piece of corriflute or cardboard with double sided tape.
The LaunchPad AlTImeter must be installed in a compartment in your rocket that is not exposed to propellants, flames, smoke, liquids, or fumes from the rocket motor or ejection system or environment. This means you must install it in a compartment that is sealed from exposure to these substances. Water rockets must seal the electronics from contact with water!
The compartment housing the LaunchPad AlTImeter must be sealed with airtight bulkheads at the top and bottom, to prevent pressure fluctuations caused by the aerodynamic forces at the nose or tail of the rocket from entering the compartment and causing false readings.
The sealed compartment must have at least one hole in it to allow for the air pressure inside the compartment to change as the rocket changes altitude. These holes are called "Static Ports". One static port is required, but more ports spaced evenly about the circumference of the rocket is better because the additional ports reduce pressure variations caused by wind on one side of the rocket, unstable flight, and buffeting during descent. The exception to this rule is that two ports is not recommended. Use 3 or more if possible.
The position of the ports on the compartment for subsonic rockets should ideally be at least 1.5 times the diameter of the compartment separated from any join, transition, or protrusion in the body tube. For supersonic rockets, the distance from the tip of the rocket should be increased to 4 or 5 times the diameter of the rocket. These guidelines will result in the highest accuracy from the altitude report, but are often impractical to construct on every rocket, so if you may have trade a small amount of altimeter accuracy due to the available space for placement of your pressure ports.
The ports must be round, and sanded smooth, with no burrs or ridges on the body tube.
The size of the static ports in your sealed compartment is important for getting the best possible results. A general rule of thumb is that for every liter of volume inside your compartment, you should have 4mm of port diameter. One hole of 4mm diameter or 4 holes 1mm in diameter will work well.
Caution:
     Avoid making holes less in diameter than the thickness of the compartment walls.
     Avoid making holes smaller than these guidelines.
     Avoid making holes over 2 times larger than indicated by these guidelines.

It is important to note that the Barometric Pressure Sensor is so sensitive, that sunlight shining on it can cause the pressure reading to change, so you should not place the sensor in a location where it will be directly in sunlight. The light can cause faulty readings or even an unintended launch detect. We recommend making a shade from opaque vinyl tape to block sunlight from hitting the sensor but still allowing free air flow to it.
It is also important to note that handling of the rocket can cause it to bend or stretch or compress in ways that can create pressure fluctuations inside the compartment with the LaunchPad AlTImeter, leading to possible unintentional launch detection or misleading altitude readings. Take care to avoid this situation.
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Parachute Deploy:

The LaunchPad AlTImeter has 2 available methods for deploying a parachute or triggering some other external event after apogee has been detected. The following instructions provide the proper connection methods and any extra modifications needed to utilize either one or both of the deploy methods. Consult the Wiring Diagrams in the Assembly Instructions Section of this manual for more example connections for deploy systems.

Servo Motor Recovery:
This method uses a common servo motor to trigger a mechanical ejection system. Such a system is a prerequisite for Water Rockets, as pyrotechnic systems are forbidden in international Water Rocket Competitions like the WRA2 Competition Rules, and could even be illegal in your area.
To add a servo motor recovery to your LaunchPad AlTImeter, you will need a Servo and a power source for the servo. A servo will have 3 wires that need connections to function:
External Deploy Apogee Output:
This method of recovery often uses an electrically ignited pyrotechnic device to eject a parachute. The LaunchPad AlTImeter provides a 3.6V digital signal which can be used to activate an external driver circuit for such a deploy system. This output could also be used to trigger some other type of circuit, such as a camera shutter or telemetry indicator. To configure the active state for the External Trigger Deploy, see the Deploy Configuration section of this document. The connection terminal for the external Apogee Output is the XIN terminal. (See the Diagrams in the Assembly Instructions Section of this manual for more information).
Note: This signal is provided for advanced users, since it requires interfacing to external circuitry. Please leave this connection alone if you are not sure of how you would connect it to a particular device.

If you wish to add a parachute deploy system to your rocket, we recommend you follow our tutorials for building a state of the art recovery system:
Parachute Tutorial
Radial Deploy Mechanism Tutorial
Axial Deploy Mechanism Tutorial

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Configuration:

The picture below shows the front of the LaunchPad AlTImeter, and all of the controls you will use to configure the deploy settings.
LaunchPad AlTImeter Configuration Controls.
LaunchPad AlTImeter Configuration Controls.
The LaunchPad AlTImeter has two configuration settings which can be modified. The configuration settings are only used when you are using the LaunchPad AlTImeter to deploy a parachute. If you are not connecting a deploy system, you may skip the configuration steps. The two settings which can be user modified are shown in the following table:
Setting Factory Default Description
Deploy Delay 0 Sec. Time delay after apogee before deploy is triggered
Deploy State True/Clockwise Polarity of deploy output and direction of servo motor

The following instructions allow these settings to be changed:
Setting Deploy State:
The parachute deploy output signals from the LaunchPad AlTImeter can be set to two different states, depending on what system you have connected.
If you are using an external igniter circuit the input signal required by that circuit will either deploy when the output from the LaunchPad AlTImeter goes high, or when it goes low. This will vary from one circuit design to another, so we have provided a way to define the deploy state of the digital deploy output.
If you are using a servo motor actuated deploy then the deployed position of the servo could be either clockwise or counter-clockwise. The direction depends on the mechanism you are using, so the position for the servo deploy is also programmable using this same method.
To program the Deploy State:
  1. Connect power to the LaunchPad AlTImeter with neither of the buttons pressed.
  2. Hold down the Mode button while pressing and releasing the Reset Button. The Red and Green LEDs will come on and stay on.
  3. Release the mode button and observe the Red LED. The Red LED will alternate between ON and OFF once every second. The state of the Red LED indicates the possible selections for the Deploy State.
  4. When the Red LED is indicating the desired Deploy State (see the table below), press the Mode button once more to save the desired Deploy State to permanent memory on the LaunchPad AlTImeter. The Deploy State will be preserved for every future launch until changed in this manner again, or new firmware is loaded.
Deploy Type Red LED Condition Deploy State
Servo Motor ON Servo Fully Clockwise (Default)
  OFF Servo Fully Counter-Clockwise
Deploy Output ON TRUE (3.6V) (Default)
  OFF FALSE (0v)
Setting Deploy Delay:
You can program a delay from 0 to 30 seconds with this setting. You can use this to hold back the parachute deploy event for the desired number of seconds after apogee is detected. This is useful in a scenario where you want your rocket to descend for a number of seconds after reaching apogee and then deploy the parachute.
To change the Deploy Delay:
  1. Disconnect the power from your LaunchPad AlTImeter.
  2. Hold down the Mode button while connecting the power source. Both the Red and Green LEDs will come on and stay on.
  3. Release the Mode button. The Red LED will begin to flash once every second, counting up the delay time interval.
  4. Press and release the Mode button again when the Red LED has flashed the number of seconds you wish to set the Deploy Delay for. For example, press the Mode button after 5 flashes for a 5 second Deploy Delay. The Deploy Delay will be saved to permanent memory for every future launch until changed.
Firmware Version Display:
After either of these settings has been configured, the Red and Green LEDs will display the current version number of the loaded firmware. You can verify that you have the latest version loaded. See the Configuration section of this manual for more information.
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Operating Instructions:

The LaunchPad AlTImeter is operated using the controls pictured in the image below:
LaunchPad AlTImeter Operating Controls
LaunchPad AlTImeter Operating Controls
Operating Mode Description:
Apogee Reporting Mode The altitude of the last recorded flight is reported
Deploy Configuration Mode Make changes to the optional parachute deploy settings
Arming Mode Operator initiated time delay before launch detect system is armed
Armed/Launch Detect Mode System is armed and waiting for launch
Apogee Detect Mode Launch is detected and system is detecting the apogee
Recovery Delay Mode Apogee is Detected and Recovery Delay is in progress
Recovery Activation Mode Recovery System is Activated
Error Reporting Mode A configuration error was detected and the error code is reported
Hardware Failure Mode A serious hardware problem was detected at power up
Show Firmware Version Mode Operator initiated output of firmware version

Apogee Reporting Mode:
When the LaunchPad AlTImeter has been powered up or reset with no control buttons pressed or has just completed a flight, it will be in Apogee Reporting Mode. In this mode the LaunchPad AlTImeter will report the altitude recorded on the last recorded launch. The recorded altitude is saved in non-volatile memory so that it will be retained even if the battery becomes depleted or disconnected.
The altitude report is displayed on the two status LEDs as well as using audible tones using a proprietary sequence of flashes/tones to report the height in feet of apogee. Use the following chart to decode the report sequence:

Note: The Red LED is associated with a low tone and the Green LED is associated with a high tone, so when the LED is indicated there will also be a tone generated if you have populated the optional Audio Transducer.
LED Condition Indication
Red LED ON for 2 seconds Start of Report
Green LED flashes 0 to 9 times Single Digit expressed as count of flashes
Both LEDs OFF for 2 seconds Separator between digits

For example, a flight of 935 feet would report the sequence:
  1. Red LED ON for 2 Seconds indicating the start of a report
  2. Nine flashes of the Green LED
  3. 2 second pause with both LEDs OFF, indicating the end of the first digit (9)
  4. Three flashes of the Green LED
  5. 2 second pause with both LEDs OFF, indicating the end of the second digit (3)
  6. Five flashes of the Green LED
  7. 2 second pause with both LEDs OFF, indicating the end of the third digit (5)
  8. The Red LED ON for 2 seconds indicating the start of the report again.
The MODE button has 3 functions in reporting mode:
  1. Press briefly to start new report at the beginning. This is useful if you lose count and need to restart and are annoyed at waiting for the rest of the report. You can start over instantly by pressing MODE briefly.
  2. Press MODE and hold it for 1 second and release it to toggle the audio output until reset or armed. This option is useful if you want to avoid powering down the LaunchPad AlTImeter between flights, but find the beeping sound annoying. You can disable the audio reporting temporarily and turn it on later. Tip: if you can avoid repeatedly opening the rocket to access the battery, you reduce the risk of breaking wires or parts of the rocket from the wear.
  3. Press the MODE button and hold it for 5 seconds to initiate the ARMING sequence just prior to a launch. You must ARM the LaunchPad AlTImeter prior to each launch, otherwise it will not record a new altitude or deploy a parachute. See the section on Arming Mode for full details.
Deploy Configuration Mode:
The Deploy Configuration Mode is used when you want to make changes to the settings used by the optional Parachute Deploy system that you can connect to the LaunchPad AlTImeter. The settings can be ignored if you are not using a parachute recovery controlled by the LaunchPad AlTImeter.
See the Deploy Configuration Mode for details how to use this mode to set up the recovery parameters.
Arming Mode:
Most commercially available altimeters automatically arm themselves after a short time interval once they have been powered up, only giving you a brief window of opportunity to close up your rocket and get it into position for launch. Often, the commercial altimeter will arm itself and begin waiting for launch detect before you are completely done, and handling of the rocket will cause a false launch detect and possibly activate the deploy system. To avoid this poor design, the LaunchPad AlTImeter uses the MODE button as an arming switch at any time when the LaunchPad AlTImeter is in Apogee Reporting Mode. You can bring the mode switch circuit to an external button for easy access, or press it with a skewer stick through one of the static pressure ports when you decide the rocket is ready for arming.
When you initiate the arming sequence, the LaunchPad AlTImeter flashes alternating Red/Green LEDs for 30 seconds to let you know it is preparing to arm. It also emits a Low/High siren sound for the first 5 seconds to audibly alert you that you have initiated the arming sequence.
During this 30 second time period, the LaunchPad AlTImeter will go through a series of self-calibrations to reduce the effects of ambient air pressure and weather conditions.
After 30 seconds, the LaunchPad AlTImeter will be armed and will emit a short beep once per second while waiting to detect the liftoff of the rocket.
Armed/Launch Detect Mode:
When the LaunchPad AlTImeter has armed itself, it begin to monitor the altitude changes it senses over time and calculates the velocity the rocket is moving upwards. A proprietary wind pressure cancelling algorithm senses a launch provided the rocket reaches an altitude of 30 feet or more. Once launch is detected, the LaunchPad AlTImeter enters Apogee Detect Mode.
Apogee Detect Mode:
When in flight after launch is detected, the LaunchPad AlTImeter begins to monitor the upward velocity of the rocket to detect when the rocket has ended upward movement. The altitude at this moment is recorded as the Apogee of the rocket and stored in nonvolatile memory in case of battery failure.
The velocity as the rocket is climbing is passed through a proprietary software filter that cancels out the pressure drop caused by the rocket passing through the speed of sound. This filter also cancels out the effects of wind and erratic flight, preventing incorrect apogee detection.
When Apogee is detected, the rocket then goes into Recovery Delay Mode.
Recovery Delay Mode:
If you have programmed a Recovery Delay time using the Deploy Configuration Options, this mode is a time delay between apogee and the trigger of the Parachute Recovery Output signals between 0 (default) and 30 (maximum) seconds. See the Deploy Configuration Section on how to change the delay.
When the Recovery Delay time has elapsed, the parachute Recovery Output Signals will activate the recovery system (either a Pyrotechnic Recovery, a Servo Motor Recovery, or Both). The Parachute Recovery Output signals will be active for 5 full seconds. After this time, the LaunchPad AlTImeter will revert to Apogee Reporting Mode.
Note: If you are not using either parachute recovery output of the LaunchPad AlTImeter, this mode is only a delay between Apogee and the time when the altitude is reported.
Recovery Activation Mode:
In this mode, the Parachute Recovery Output signals will be active for 5 full seconds. During this time the deploy system you have connected should deploy the parachute or some other recovery system. After this time, the LaunchPad AlTImeter will revert to Apogee Reporting Mode.
Error Reporting Mode:
After each flight, and after each power up or system reset, any configuration errors or problems are reported in this mode. This mode will read out errors in a similar way to the way that Apogee is reported in Apogee Reporting Mode, except the roles of the Red and Green LED are reversed. If the Red LED is flashing the count, then you will know that the count is an Error Number that is being reported.
The possible error codes are listed below:
Error Condition Reason
2 Memory Error A problem was detected writing to permanent memory
3 Sensor Error The Pressure Sensor is reporting a failure

Hardware Failure Mode
A serious hardware problem was detected. This can be caused by the CPU becoming physically damaged due to misuse or improper voltage, or it has not been programmed correctly. Improper connections of the wiring can also cause this error.
The error conditions are as follows:
Error Condition
Power LED ON, Red and Green LED OFF Damaged MSP430 Microcontroller
Power LED ON, Red LED ON Bad Programming of MSP430 or Pressure Sensor wiring error

Show Firmware Version Mode
You can read out the currently installed firmware version by observing the LED indicators when this mode is activated. The firmware version number will blink a 3 digit value using the same blinking patterns used in Apogee Reporting Mode, except the 3 digits will report the firmware version. For example, the flashed code digits 1, 0, 0 would indicate firmware 1.00 version.
Two methods are provided to activate Show Firmware Version Mode:
  1. Loading new firmware activates this mode in place of Apogee Reporting Mode until a launch has been recorded.
  2. Manually configuring a deploy delay (any value, even 0), or manually setting a deploy state will replace Apogee Reporting Mode until the next launch is recorded. See the configuration setting section for more information.

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Frequently Asked Questions:

In any product of this complexity, there are always going to be common questions that arise. This section groups together many of the basic questions people have about the LaunchPad AlTImeter. Please check here for the solution to any questions you may have before contacting U.S. Water Rockets. If you cannot find the answer to your issue here, then feel free to contact us with your question. You can post questions to us on The Water Rocket Forum, Facebook, or Twitter.
Q. Where do I order a completely assembled LaunchPad AlTImeter?
A. The reason the LaunchPad AlTImeter is so affordable is because you build it yourself from a small number of separate parts. We provide the plans and the software for free, and you easily build the hardware and save money. We're interested in helping people do it themselves, not manufacturing and distributing products.
Q. What's different about the LaunchPad AlTImeter that would make it worth building, as opposed to a commercially available Altimeter?
A. There are several reasons:
  • The LaunchPad AlTImeter costs much less than other Altimeters because U.S. Water Rockets is giving away the firmware for free, and you build the hardware yourself.
  • The LaunchPad AlTImeter is the latest release with the newest innovations. Technology is always advancing and you will always find superior performance in newer designs.
  • The LaunchPad AlTImeter is the first Altimeter design specifically created to address the requirements of both Pyrotechnic and Water Rockets.


Q. What does the LaunchPad AlTImeter do differently than other Altimeters that makes it suitable for Water Rockets?
A. Once again there are several answers:
  • It has the ability to drive a Servo Motor powered deploy system, which is the preferred method of parachute deploy for Water Rockets because the WRA2 competition rules forbid using black powder and similar types of pyrotechnic deploy systems. You can find great designs for servo deploy systems on our website: http;//www.uswaterrockets.com/construction_&_tutorials/menu.htm.
  • Some water rockets are designed to accelerate very slowly and this can cause a regular altimeter to fail to detect the launch, resulting in no altitude reported, and no parachute deploy. Slow acceleration can also cause a regular altimeter to detect launch only after the rocket is well into flight. This results in a lower than actual altitude to be reported. The LaunchPad AlTImeter uses a proprietary launch detect system which can detect low acceleration launches but is also quite immune to false triggers due to wind gusts, if you follow the installation guidelines provided in this document.
  • Combining the functions of a regular altimeter with the functions of a water rocket servo timer for less than half the cost of either one of those products, the LaunchPad AlTImeter helps to promote the sport of Water Rocketry.


Q. Where can I get the source code, so I can add my own features?
A. We have chosen not to publish the source code because this type of device could be easily modified from a hobby/educational instrument into something that could be used to hurt people or damage property. We are constantly adding new features to the basic design over time, so chances are anything you can think of to add to the software is probably already in the testing stage in our labs or in the field.
Q. Why can't I use the 9V battery option when I use the servo deploy feature?
A. Most small hobby servo motors are only rated for about 6V input power, so you would have two power sources on your rocket. To save room and space you can run the entire system from 6V.
Q. Does the LaunchPad AlTImeter work in supersonic rockets?
A. It was designed to work in this realm, but we have not yet flown it on a supersonic test flight to confirm it works properly. We have only conducted subsonic test flights at the time of release.
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Troubleshooting:

This section will help you resolve the most common problems that people encounter with the LaunchPad AlTImeter.
From time to time you may encounter an issue that you do not understand. Use this troubleshooting guide to help resolve problems.

Issue Resolution
The altitude started reporting while I was setting up to launch.   •  A pressure variation that resembled a launch pressure drop has triggered the launch detect.
The altitude started reporting while I was pressurizing my water rocket.   •  Be careful not to flex rocket while handling it, causing pressure changes inside.
The altitude started reporting while I was waiting to launch.   •  Make sure pressure leaks from within pressurized components of your rocket are not affecting the readings.
    •  Make sure sunlight is not hitting the pressure sensor, leading to bad readings.
    •  Windy conditions in combination with poor air inlet portals can cause false triggers. Refer to the installation instructions for proper inlet design recommendations.
The height reported is impossibly high.   •  A pressure fluctuation has caused sufficient false altitude readings to register as a valid data point. This is usually caused by a very unstable rocket flight, or a crash event.
My rocket did not report a flight.   •  There can be several reasons for this:
    •  You did not arm the system before launching.
    •  The rocket did not achieve sufficient speed or altitude to trigger a launch.
    •  The pressure inlet ports are too small or have become blocked.
    •  The battery became disconnected before the launch event.
    •  A crash event disrupted the launch detection system.
Every so often, things go wrong. This troublshooting guide may help.
Every so often, things go wrong. This troublshooting guide may help.

For technical support, please use the LaunchPad AlTImeter technical support forum.
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Specifications:

Measurement:  
Resolution: < 1 foot (30 cm)
Minimum Apogee: ~32 feet AGL (10 meters)
Maximum Apogee: ~32,500, AGL
Minimum Altitude: -1,800 feet ASL
Maximum Altitude: 37,200 feet ASL
Calibrated Accuracy: +/- 1% max
Analog/Digital Converter: 24-bit
Sampling Rate: >100hz
Slow Launch Detect: Yes
Wind Gust Filter: Yes
Nonvolatile Memory: Last Apogee and Deploy Settings
   
Deploy:  
Digital Output: 0VDD and 3.6VDC at 5mA Max
Servo Output: 0.5ms to 2.5ms at 50Hz, 3.6VDC p-p
Deploy Event Duration: ~5 seconds
   
Operator Interface:  
LED's: Power (1 Green), Status (1 Green, 1 Red)
Switches: Reset (S1) and Mode (S2)
Audio Enunciator: 85dB
   
Power Requirements:  
Current Required: 25mA average (Add 10mA if Audio Enunciator is used)
Battery Input:
 		 3.7VDC to 10VDC (Non-Servo Configuration)
3.7VDC to 6VDC (Using Servo Parachute Deploy Configuration)
Battery Life: 40+ Hours on typical 9V transistor battery (non servo version)
   
Environmental Requirements:  
Operating Temperature: -20°C to +60°C
Storage Temperature: -40°C to 90°C
Battery Life: 40+ Hours on typical 9V transistor battery (non servo version)
LaunchPad AlTImeter Validation Test hardware.
LaunchPad AlTImeter Validation Test hardware.

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Creative Commons License LaunchPad AlTImeter by U.S. Water Rockets is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported License.