Saturday, August 29, 2009

Steve's rocket story 1969/70

Here's a story from Steve Dempsey about the second rocket trip sponsored by Mr. Karge. I think this was early 1970. We almost bought the farm on this one...
Old memories are dangerous, but here's what I recall:

I was only at the final trip (what Charlie calls the "second" trip). I don't think it was intended to be the final launch, but that's how things turned out. I'm pretty sure this was in our senior year (69-70), probably in the late fall, as I don't recall it being very hot. The previous launches had been with relatively small steel tubes, 1 - 1.5 inches diameter, but Dan and Jim wanted to try something larger.

Charlie's right about the general design, but I think it was 4 inch seamless steel tube and was approx. 8 feet long. Powdered zinc and sulfur was the fuel, with a small clump of black powder and an electric igniter at the base. There were three stabilizer fins welded to the bottom of the tube. The payload held a parachute and consisted of a piece of 5 or 6 inch pvc pipe, sawn in half and then taped together. A pendulum switch was supposed to make contact as the rocket tipped over at the top of the flight, detonating a small pipe bomb (gulp!) that would separate the payload housing and release the parachute. There was an external plug to arm this circuit. The whole thing weighed about 250 pounds and took 5 people to lift.

The launch tower was a tripod made of heavy angle iron. One leg extended above the others and served as a launch rail. This thing weighed as much as the rocket.

So, the rocket was fueled, mounted on the launcher, and the payload circuit was armed. I and a few others (Dan Hogan's sister Hilary Hogan was among the group) drove to a point about a mile away. Our job was to track the rocket from a distance and try to get an estimate of the height as well the landing point. We had walkie-talkies to communicate.

The countdown commenced, and at zero there was a small puff of black smoke, then nothing. I was told it wasn't unusual for this to happen and then a few seconds later have the fuel ignite, so we waited. A hour later we decided it was probably safe enough to go back.

The igniter and black powder had to be replaced. So we lifted the rocket off the launcher and tipped it over to examine the bottom. That's when someone noticed that the payload circuit had not been disarmed! So five people stood there holding a 250 pound rocket loaded with fuel and wondering if the pipe bomb in the nose was going to go off. We didn't want to move for fear of triggering it. It seemed like an eternity, but Jim Blair decided to just pull the arming plug. No boom. We lived.

This also told us the payload circuit was faulty, but we decided to try and launch again anyway. The igniter was replaced with new black powder, and we retook our position a mile away. 3...2...1...FIre....

This time there was an instantaneous detonation. All we could see at the launch site was a massive cloud of dark smoke. Then someone spotted the rocket. It was spinning furiously around it's long axis as it arced over, then a shrill whine could be heard as it descended and impacted. A nice parabola, but no parachute.

The folks back at the launch site told us over the walkie-talkies that they were OK. So we headed back there. At this point a huge mushroom cloud of smoke had risen, then spread out to nearly fill the sky above the entire valley that Clark Dry Lake sits in. We wondered what people in Borrego Springs thought of this.

When we got back to the launch site we realized the magnitude of the explosion. The launch tower had been folded into a pretzel shape. There were small pieces of parachute material scattered around.

We found the rocket. It had buried itself nose first, about 3-4 feet deep. No crater, it looked like the rocket had just been injected into the earth. The nozzle was gone, and one of the fins had been severely bent. It took about an hour to dig it out.

The results:
1. We estimated a peak height of about 4000 feet.
2. The bent fin caused the rocket to spin.
3. 8mm movies taken from the launch site showed a flash of fire, a lot of smoke, and then a few small pieces of parachute material floating down. The rocket itself appeared in just the first few frames, but from that it was estimated that it took off with a force of 22Gs.
4. We surmised that the rocket essentially blew out its nozzle at launch and travelled right through the payload. The nozzle was never found to my knowledge.
5. We presumed the fin was bent as it hit the launch tower on its way up, but we never understood how the tower was so heavily damaged.