LOHAN rolls out racy rocketry round-up
Progress to date on our audacious spaceplane mission
3: Rocket motor heater
One big concern is the effect of cold on the rocket motor at altitude, where the temperatures can get down to -60°C.
After a few sleepless nights imagining a frozen cylinder of ammonium perchlorate composite propellant (APCP), we decided to launch a pre-emptive strike on the problem and ordered a space-grade Polyimide Thermofoil flexible heater:
This will be wrapped round the motor casing, with a layer of space blanket as insulation, and held in place with some heat-shrink tubing.
The effective area of the heater is 46.54 in2 (300.257 cm2), and its resistance is 64Ω. A quick calculation revealed that at 12V, it'd be running at 0.1875A and pumping out 2.24W - a watt density of 0.05W/in2, or 0.0078W/cm2.
Once we've got the rocket casing and heater in a tight embrace, we'll test to see just how much juice we need, and for how long, to the keep the temperature up.
We have three options: pre-heat on the ground, heat during the ascent phase, or a combination of both. Whichever ultimately proves necessary, it won't impact on the Vulture 2's weight, since any batteries will be external.
If we do heat during the ascent phase, we'll have to work out an umbilical system to supply power to the heater, and which will detach easily when the aircraft launches.
We're sure readers have some bright ideas as to how that can be done with the minimum of fuss.
4: Fantastical flying truss
As the above vid shows, we've done some testing to see just how our flying truss will, er, fly, and now have a definitive design, seen here in our lovingly-crafted one-quarter scale model:
You'll note it's sprouted a tail, which helps keep the truss orientated into the wind. We've just ordered the carbon fibre rods and fittings to construct the full-fat, two-metre long truss, so we'll do more testing when we've put that together.
What we can't do at this stage is add the titanium launch rod, since we'll need the Vulture 2 to work out its exact positioning.