Project HARE BRAIN describes a project to built a high altitude launch platform for launching a small sounding rocket from a lighter than air, aerial platform. For the first series of tests, the plan was to use a small lightweight rocket launched from a tethered aerial platform to prove the concept.

LAUNCH VEHICLE

The rocket chosen was a Check-Six rocket. This is one of the Rugged Rocket kit product line, manufactured by Impulse Aerospace. As the name suggests, the rocket, although very small, is constructed more like a High Power Rocket than a model rocket, and as such offered a more robust launch vehicle, at the expense of being heavier (100 grams).

The rocket came with an integral Nomex flame shield instead of the more traditional wadding. This was discarded in favour of a miniature scratch built piston recovery system. The integral payload bay, whilst rather on the small size, was just large enough to squeeze a scratch built altimeter in (built around a PIC 16C84 CPU) - this did take an awful lot of squeezing however.

LAUNCH PLATFORM

After much calculation, the launch platform chosen was a number of Helium filled radio controlled flying saucer envelopes, with a central carbon fibre boom structure. The launch tower was designed to be slotted onto the carbon fibre boom, and locked in position at the centre of the boom. This longitudinal arrangement offers a great deal of flexibility with regard to the number of balloon envelopes used, as well as allowing the launch platform to be re-used. At some point in the future, it is planned to fly the launch platform using a number of electric powered ducted fans.

LAUNCH TOWER

For the first series of tests, the launch tower was a disposable plywood and balsa framed rectangular tower. 2 tubes on either side were fitted to enable the carbon fibre rods to slide through them to mount the tower. 4 vertical rods were fitted to allow the rocket to slide down in between them. The reason for making the structure out of these materials was to save weight. The target for the launch tower weight was a maximum mass of 150 grams.

Written by Richard Osborne