Introducing the USWR Split Collar Cable Tie Launcher

History of the USWR Split Collar Cable Tie Launcher.

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.

Totally new water rocket launch release mechanism design released

Introduction:

Water Rocket launcher mechanisms are an important area of Water Rocket design which has received very little attention by researchers for more than a decade. There appear to be only a handful of teams doing work in this area. A sampling of hundreds of discussions taking place on the Water Rocket Forum shows that virtually every team actively participating have been using variations of only two existing launching systems which have remained unchanged for many years.
Both of these designs have been reliable workhorses, and have served their respective users needs, in spite of their weaknesses:

1. The Gardena Release:

The Gardena system is made from garden hose quick-connectors. This release is hampered by the small nozzle diameter which restricts maximum speed and altitude, and is difficult to combine with a launch tube, necessitating the use of cumbersome external launch rails. The cheap plastic garden hose connectors which form the core of the release are also not suitable for high launch pressures, limiting their appeal to mostly novice rocketeers.

Gardena launchers limit nozzle diameter and make use of launch tubes difficult. Even this custom 3D Printed nozzle cannot exceed 9mm in diameter.

Gardena release will require the addition of guide rails to our launch pad.

2. The Clark Cable Tie Release:

The Clark Cable Tie system requires a bit more skill to construct, but it allows larger nozzle diameters and internal launch tubes, making them the attractive choice for high performance water rockets. The weakness of this design is that the force required to activate the system increases as pressure in the rocket increases, making the release difficult to trigger at high pressures. Even at moderate pressures, the activation force can be large enough to break the release cord or tip over the launcher.

A very early Clark Cable Tie version of our launcher.

This launcher was difficult to operate when pressure in the rocket was ramped to the limit of the rocket tube.

The vertical release collar motion needs to be translated into a horizontal motion of the release cord.

High pressures increase the friction holding the release collar, making it very hard to move.

Eventually the collar is so hard to move it can tip over the launcher or break the release cord.

U.S. Water Rockets did a great deal of research into release designs when we were incrementally raising the Water Rocket World Altitude Record to over 2,000 feet. The high performance rocket designs necessitated the use of the full bore nozzle, making the Clark cable tie system the obvious choice. To overcome the friction in the release resulting from the high pressures, we determined that the use of mechanical force multipliers would be needed. Our solution was to add a system of pulleys to increase the release cord force, and this idea worked well as we increased launch pressures for a number of years. Other rocket teams observed our progress and attempted to address the force issue we identified by using levers and other types of force multiplication hardware.

Pulleys were added to the design to amplify the pulling force of the release cord.

The pulleys also allow the motion to translate from horizontal to vertical.

Evnetually even the pulleys were not able to easily release the rocket.

After a number of revisions to our pulley system to keep up with ever increasing pressures, we realized that the concept of moving the release collar to launch the rocket was fundamentally the wrong approach, and that simply opening the collar to release the rocket would be much easier.
We then constructed a release collar that was split in two halves and would hold the rocket by simply holding the collar halves in place over the cable ties and releasing them to separate and fall away when launching the rocket. We dubbed this release system the "U.S. Water Rockets Split Collar Release".

The new design by U.S. Water Rockets divides the collar holding the cable ties into two or more sections.

The collar can open to release the rocket instead of needing to slide off.

The only question that remained was how would the collar be held in place and easily released at launch. The solution to this was to use a commonly available pair of locking pliers, with the launch release cord connected to the tab on the pliers that releases the jaws. We also experimented with various locking clamps, but our preference has been the pliers because of their low cost and availability worldwide.

A pair of locking pliers are all that is needed to hold the collar in the closed porition.

The release cord is connected to the tab on the locking pliers that opens the jaws.

The split collar design holding a water rocket in place.

This particular design has been one of the key advances that contributed to the success of our world record flights, and has been a team secret for several years. We decided to release this information to the public at large to celebrate the anniversary of our 10th year since our team first formed to pursue the world record, and to encourage other teams to join the competition for the record, which has become stagnant for far too long. We hope that sharing these ideas will liven things up!
A detailed step by step tutorial can by found by viewing: USWR Split Collar Launcher Construction Tutorial
We've tested a number of variations of this design and believe there are plenty of other new ideas that can be explored with this release. A few of the adaptations of this release are:
1. We added spacer blocks to the sides of the collar, which allows the locking pliers to pass over fins projecting beyond the rear of the rocket. By passing over the fins, the clamp cannot strike the fins when it snaps open like it does when the clamp passes in from under the fins.

Spacer blocks were added to provide clearance for fins.

2. We added aligning keys into the cut when splitting the collar, which makes alignment of the collar halves easier.

The cut line can be keyed to make alignment easier.

3. We added cups to the collar halves so that locking pliers with smooth faces would not slip off.

Any locking clamp like this welding clamp can be adapted to this design.

This welding clamp has smooth faces which could slide off the collar if not adapted.

The smooth clamp faces were no longer an issue once we added cups to hold the clamp in place.

There are plenty of other ideas for this launcher that we are exploring. We hope the water rocket community will find this release design as useful as we have!
USWR Split Collar Cable Tie Launcher Video: