Picture of 2 Liter Bottle Water Rocket and Launcher Pad
This is my design for a 2 Liter Bottle Water Rocket and Launcher Pad.

First, I know this is not the first 2 Liter Bottle Water Rocket launching system ever designed.  This design actually took inspiration from several of the designs that NASA had posted.
Second, depending on where you buy your parts and what stuff you have on hand, this may not be the cheapest design either.  You will need to decide if this design provides you the characteristics that warrant the potential additional costs over alternative designs.  I had some very distinctive goals with this Water Rocket Launcher system that I personally felt the other designs did not fulfill.  For example:
  • The design needed to survive rapid repeated use in a very short amount of time.  Scaling to 100+ repeated launches in a day with the ability to turn around and do it again the next day.  Not only did this mean it needed to be rugged enough to last, but it had to have a system that allowed for quick resets.
  • The design needed to allow children 6-17 and adults of all ages to pressurize and launch the system from a safe distance (~20 feet). Although staging / clamping and safety check would be done by an experience adult / young adult prior to pressurizing, it was important to me that each participant had the opportunity to be involved in the act of pressuring and releasing the Water Rocket.

Third, I know the design is not perfect.  I am hoping, like I did with other designs I found, someone will see this design, identify refinement opportunities, and be inspired to improve on it.

Disclaimer:  This “Instructable” is provided “As Is” without any express or implied warranty of any kind including warranties of merchantability, noninfringement, or fitness for a particular purpose.  The Author of this “Instructable” does not warrant or assume responsibility for the accuracy or completeness of any information, text, graphics, links or other items contained within this “Instructable” post.  In no event shall the Author of this “Instructable” be liable for any damages whatsoever (including, without limitation, lost profits, business interruption, lost information, damaged electronic equipment and circuits, damage to property) or be liable for any personal harm / pleasure / death whatsoever (including intentional or unintentional, without limitation, cuts, scratches, lacerations, punctures, bruises, inhalation, swallowing, or insertions) arising out of the use of or inability to use this “Instructable”, even if the Author of this “Instructable” has been advised of the possibility of such damages or personal risks.

In short... Do your own engineering work and analysis of the approach for your specific implementation to determine validity, safety, and assume accountability for the outcome of your engineering assessment; assess and mitigate the risks specific to your scenario and skill level. Use good sense on how, where, and if to use this approach; if you are unsure, do not use it... I would have said common sense, but common sense is definitely not common.

This Bottle Water Rocket Launcher Design has 3 major system components:
  1. 2 Liter Bottle Water Rocket & Pressurization Plug: This system stores the pressurized water and air and, on Launch Pad Clamp release, allows the 2 Liter Bottle to generate thrust projecting the 2 Liter Bottle housing into the air.
  2. Launch Pad: Holds the 2 Liter Bottle Water Rocket while the system is being pressurized and provides a mechanism to quickly release the pressurized water / air.
  3. Modified Bicycle Pump / Pressurization System: Although any bicycle pump can be used to pressurize the system, this modified version provided additional hose length and pressurized water back flow protection.  Whether you use this modified bicycle pump or any off the shelf bicycle pump design, a bicycle pump or air compressor is required.

Summary of Procedure:

Launch System Component Assemble
  1. Getting your Materials (Parts & Tools)
  2. Assemble Pressurization Plug
  3. Assemble Launch Pad Clamp Bracket and Hinge
  4. Launch Pad Base preparation
  5. Launch Pad Base Pressurization Plug Housing rough-in
  6. Launch Pad Base Pressurization Plug Housing tuning
  7. Fastening Launch Pad Clamps to Launch Pad Base
  8. Place the Launch Pad Clamps under return spring tension
  9. Secure Stabilization Feet to Launch Pad Assemble Base
  10. Affix Velcro Launch Pad Clamp release strap
Bicycle Pump Optional Step:
  1. Disassemble Bicycle Pump
  2. Assemble Bicycle Pump Hose Extension
  3. Reattach Bicycle Pump Hose & Head
Operation, Safety & Additional Notes
  1. 2 Liter Bottle Water Rocket and Launcher Pad Operation
  2. Safety and Additional Notes

Hi, This is a very comprehensive set of build instructions with very good safety notes included. A definate must build for when the grandchildren are next round to stay. I see hours of endless fun for me oops! I mean the grandchildren. As an addition to the projectile construction may I suggest listed in Instructables:-

Water Rocket
by JoeGadget on April 26, 2014

Well done keep the space faring going.