FAR

Fixed Airframe Rocket

Pathfinder 1/2
in use: general testing vehicle

Because the math behind waterrockets is quite complicated, we decided to build the pathfinder test-vehicle FAR (fixed airframe rocket).
As the name suggests, it is fixed to the ground, so not quite a "rocket" yet. But it is basically an early prototype of the planned Poseidon-Rocket, which is held down by load cells.
This enables us to measure the thrust curve and change in mass over time. With that data we should be able to build a mathematic model.

Block 4 Specifications

Height
1710 mm
1710 mm
Diameter
74 mm
74 mm
Dry Mass
2750 g
2750 g
Propellant
Water, 4 kg
Water, 4 kg
Pressurant
Air, 3 MPa
Air, 3 MPa
max. Thrust
102 N / 10.4 kgf
102 N / 10.4 kgf
tot. Impulse
220 Ns
220 Ns
Apogee
no lift off
no lift off

Test Results

We conducted multiple thrust test, with FAR mounted on loadcells to measure the force.
Later tests used higher and higher pressures, up to 33bar. There were different variations of the tanks, valves and nozzle, for example the new carbon composite (opposed to previous PVC) tanks used in the latest tests.

FAR Block 3

PVC tanks, C-D nozzle, 30+ bar rated valve

Chart by Visualizer

FAR Block 4

Carbon composite propellant tank, PVC pressurant tank, C-D nozzle, 30+ bar rated valve

Chart by Visualizer

FAR High Pressure Tests

Over the summer we tested the FAR prototype under higher pressure. For that purpose we bought a 300bar air cylinder and regulator.We conducted the high pressure tests to research thrust and burntime under flying pressures of about 30bar and to check the experimental data against our simulation. Hydrostatic tests At first, to verify that the PVC tanks of the FAR prototype won't explode under the high pressure - the tanks are rated for 10bar, we want to use 30bar - we conducted multiple hydrostatic tests.Hydrostatic - as the name suggests - means we fill the test tank completely with water ...