SCRAPHEAP

OR HOW NOT TO LAND A ROCKET ON NATIONAL TV

Probably my most infamous TV appearance was on a Channel 4 TV programme called Scrapheap. Whilst it was not entirely innacurate in capturing my enthusiasm and, what some may term my eccentricities, it sort of gave the impression that I was merely mad, rather than mad, but with 2 Physics degrees, half an Astrophysics Ph.D, Chartered Status, had worked with missions for NASA, ESA and the Russian space agencies, and was running a successful IT company.

I do tend to get carried away with enthusiasm for rocketry (and other technically related things) but then again, it's not done me any harm in getting jobs, contracts etc over the years - although Scrapheap was not so helpful.

To summarise, yes, I may be what some would call mad, but I'm certainly not stupid :-)

The Rocket

The rocket was christened the rather cool name of "Space Cadet" by fellow team member, Kali. The rocket itself consisted of two plastic water filter tubes, an aluminium tube fashioned from a sealant gun, 4 aluminium fins (clipped delta configuration for those who are interested) which were pop rivetted onto the plastic tubes, and a drainpipe payload section carrying a commercially available IAX-96 altimeter/accelerometer.

The motor was secured into the airframe by means of a number of wooden centring rings. These were made from sheets of wood cut into a circular shape, and then cutting circles out within these, to make ring shapes. The motor casing could then be inserted through the rings, with the aft motor closure butting up against the rear centring ring, and transferring the thrust loadings to the airframe through the rear centring ring.

The motor was a commercially available Aerotech I-195J Blackjack solid reloadable motor, with an average of 195 newtons (19.5 kilograms) of thrust for 3 seconds, and a total impulse of 600 Newton seconds. The team experts were informed in advance that there would be 4 Aerotech solid rocket motor casings hidden on the set (they were all 38mm diameter Aerotech rocket motors). We were informed what performance each motor had, and both of us had, in any case launched rockets using these motors before, so we knew how they performed. The hope was then that the teams would find the largest rocket motor casing of the 4. Unfortunately, the Orange Team found the largest rocket motor casing, so we in the Yellow Team had to console ourselves with a few lower thrust motors - the first reason for making the rocket small, to enable it to compensate for the increased thrust of the other team's motor.

I did consider clustering and staging to compensate for the lower thrust, but both were non-starters, clustering because the motors were all differing thrusts so there would be a major thrust imbalance, and staging, because we couldn't find a suitable battery and capacitor to light an upper stage, and in any case, knowing when to light a second stage would be a big problem (normally, an onboard accelerometer or timer is used). A clockwork timer would work at a push, and it wouldn't be the first time one has been used on rockets, but with time being so pressing, it was going to be nigh on impossible to find the right components in a junkyard. Still, I did manage to seriously scare the production crew with my ideas!

Given the time available, building a rocket powered by solid propellant was the best solution that the TV company could have used. Yes, a liquid propellant rocket engine could be built in a day, but building a liquid engine that would (a) work reliably, (b) be sufficiently light to fly, and (c) have sufficient thrust to lift a rocket more than a couple of feet, would be nigh on impossible. A hybrid rocket motor would have been another option, but again, without access to lightweight materials, it would be quite difficult to get it to work in such a short timescale. Given those drawbacks, the use of a motor where solid propellant could simply be loaded into a commercially available solid rocket motor casing, and would have a known amount of thrust was by far the most effective use of the time available.

The choice of 4 fins was made, because with the absence of rocketry simulation software, using 4 fins rather than 3 fins erred on the side of caution in terms of stability of the rocket on the ascent. 3 fins would have upped the altitude a bit, but I felt safety would be better served with 4 fins. The aluminium fins were pop rivetted onto the plastic tube which held the motor.

Clearly, there will always be a limit to what can be achieved in terms of building a rocket, when using the limited resources available in a junkyard, so because of the generally heavy materials available (no fibreglass or carbon fibre tubing on the junkyard unfortunately), I wanted to go for as small a rocket as I could get away with, both in terms of diameter (to reduce frontal drag), and in terms of length (to reduce surface/parasitic drag). This would potentially increase the altitude that could be reached.

The altitude reached

The altitude reached by rocket built by the team I was in was somewhat higher than that indicated on the TV programme, also, the altitude reached by the other team's rocket, was somewhat lower than that indicated on the TV programme - again, I guess it makes for better TV if the altitudes were seen to be closer.

What Happened ?

Alright, so what happened ? Why did the rocket crash ?

Well, as was seen on the TV show, the wadding (cabbage), was packed too tightly. Far too tightly. As a backup, the two halves of the rocket should have split in two, pulling the parachute out into the airstream so that it could inflate properly.

The problem here, was that I had not made it clear enough that we needed plenty of line connecting the two halves of the rocket, rather than a short length of line. This was a big mistake on my part - I screwed up. Unfortunately, it is not seen on the TV programme that I did say that I didn't think the recovery system would deploy because it was packed in too tightly. I guess it makes better TV to omit things like that!

What this meant was that the ejection charge fired on time, but the cabbage was well and truly jammed in, and didn't push the parachute out of the rocket. The rocket then tipped over as it was supposed to do, the two halves separated a short distance, but because the length of line between them was so short, instead of the parachute being pulled out, the two halves slammed back together, so the rocket continued downwards ....in a dive. The resulting impact smashed the nosecone containing the snow globe, and cracked open the tube containing the altimeter.

Why use cabbage ?

In model rocketry, lettuce is sometimes used as wadding, both because it reduces the chance of the parachute getting burnt by hot ejection gases, and also because it is biodegradable. In a higher power rocket, either a flame shield (a piece of cloth made from flame proof materials such as Nomex), or an internal piston is used to prevent the parachute getting burnt.

Whilst the choice of cabbage may have seemed amusing to those unfamiliar with rocketry, it was just an appropriate substitute given the materials available. I did not choose to use an internal piston because pistons can jam, and where a rocket is being made from less than optimal materials, I felt this would be a liability.

The Experts

Apart from myself, the other team expert was Charles Simpson. I know Charles well since he is not only another UK rocketeer I see at UK rocketry launch events, but him and I have served alongside each other for 8 years on the United Kingdom Rocketry Association (UKRA) Committee - in fact, Charles served as chairman for 3 years of that 8 years. We've known each other since 1996.

Charles has launched considerably less High Power Rockets than myself (about half as many in fact), but that is mainly because he has had less time to attend launch events. He has however, attained the highest formal certification for High Power Rocketry both in the UK and the U.S. namely UKRA Level 3 certification and Tripoli Level 3 certification, whereas I have UKRA Level 2 certification and Tripoli Level 2 certification. He's very good.

The Judge

The Judge was Dr Chris Welch. Again, I know Chris from the time I spent in the formation of the Space Education Council, of which he has been the Chair for several years, and previously through UK-SEDS from 1993 (Chris served as the UK-SEDS Chair in 1994 and 1995, and I served on the UK-SEDS Council in 1996). Chris is an all round nice guy, and a lecturer at Kingston University. He was one of the applicants for a British Astronaut/Cosmonaut for the Juno Mission to the Russian Space Station Mir, and got down to the last 25-30 or so, which was incredibly good going. He also served on the British Interplanetary Society (BIS) Council.

The "Buzz" thing

My nickname was never ever "Buzz". Not before the programme, not after the programme. Put that down to the TV crew inventing a nickname for me. They asked me if I had a nickname before the programme, and I said "apart from being called 'mad', no". I was somewhat surprised when I turned up on set to find out I would be called "Buzz"!

The "Mad" thing

Am I as mad as I came across in Scrapheap? Well I guess I can only really go on what my friends say, and the general consensus was, that I "toned" it down a few notches for Scrapheap. I can't really argue with that - I was on my best behaviour for Scrapheap, albeit focussed on the task in hand. I just get these blinding flashes of inspiration, and that's it, I'm away! If you're ever on a train and you see a couple of people animatingly discussing ways to build a stable wormhole for space travel or something equally esoteric, oblivious to the bemused stares around them, then yes, chances are, it will be me.

See Also

Hybrid Rocket Science, Hybrid Rocket Help Clinic, Amateur Hybrid Motors, Amateur Liquid Rockets, Guidance, Gimballed Motors, Launch Controller, UK Rocketry Vendors, UK Rocket Groups, UK Space Organisations