Steam Rocket

Dear friends,

Yesterday my son and I took part in the Great Dinosaur Safari and picnic at Crystal Palace. To avoid the young ‘uns being bored, I figured we needed some suitable steamy entertainment, and decided to resurrect the old hydrogen rocket that we stole the electrolysis cell from for the Egg Cannon. But the rocket never worked very well and the ignition element had died, so a little upgrading was in order. But what better for a Steampunk picnic than a hydrogen rocket; after all, hydrogen + oxygen + spark = steam!

The original D cells weren’t up to the job so in went a 12V 3.3Ah lead-acid rechargable battery – that should improve hydrogen generation! Next we needed a box to hold the battery, to control hydrogen generation, and to ignite the resulting propellant. And some way to tell whether we’ve got enough battery charge remaining. So the control centre is made from an old box I had lying around, the fake-leather cover of a writing pad, some etched copper circuit boards to strengthen where the switches attach and to look decorative, and whatever switches and connectors I could find in Maplin at short notice. The ammeter is WW2 vintage, and is wired in series with a 200KOhm resistor, so that every 5uA actually indicates 1V across the electrolysis cell. 60uA indicates a good battery.

The rocket stand is made from my old favourite: copper pipe. The electrolysis cell was unmodified from the original rocket, except that the ignitor no longer works. To ignite the hydrogen/oxygen mix, I melted some thick copper wire into the launch tube, leaving a 5mm gap between the two ends. To this I added a miniature 8KV voltage generator, also powered from the 12V battery, and switched from the missile control switch covered with the big red safety cover. The safety cover is not just for show – when I was assembling the ignitor, I accidentally shocked myself from the still-charged output capacitor, and my left arm wasn’t quite the same for the rest of the evening. Finally the rocket was painted to look a little more in keeping with the launchpad.

I didn’t get a change to test it before packing everything up and rushing off to the safari. Miraculously, it all worked first time! We got off a couple of very good shots, reaching perhaps 200feet altitude. Unfortunately on the third shot, the electrolysis cell gave out. This was the one part I didn’t expect trouble from. It turns out the anode mesh grid had completely eroded, breaking the circuit. Maybe we had fired too many eggs at Easter? Not hard to repair once we got home, but a little disappointing nonetheless. Still, the concept has been publicly demonstrated: the steam rocket lives!

Cheers,
Fzz

Generating hydrogen and oxygen:

Ready to fire!

Ready for lift off – open the blast doors. What blast doors? Damn, knew I forgot something!

Testing the igniter:

Assembling the rocket at the picnic (picture courtesy of Marchioness Cherise):

Lift off (video by Tiny5th):