MARS rocket shown on Sky TV

Early November and the MARS rocket Deimos 2 STV was flown for the Sky Television programme skyrocket. The programme was aired later in the month.

The 14 foot tall Deimos-2 STV finally took to the skies on a solid motor cluster again, in the presence of a rather impressed TV crew, for a programme that was shown on Sky 1 later in the month.

Unfortunately, from the MARS point of view, the flight was "less than optimum" albeit somewhat more exciting, although having said that, in an unusual twist, we ended up getting more useful data from the flight that we would have done if it had all run smoothly.

Due to a lack of the normal igniters, a fall back option was taken on Wednesday, on the way up to Pete's Farm, whereby igniters from a firework factory were used, which were then dipped in Firestar. 2 composite propellant solid motors were static tested to determine the time taken for ignition. Both motors ignited successfully, although one of the motors exhibited a strange pulsation in the thrust (not connected with the igniters). The igniters seemed to ignite instantaneously, and burned, rather than exploded - exactly what was needed.

Wednesday also saw Iain Colledge launch (and sadly lose) his Aerotech Initiator on an Aerotech single use composite G-class motor(G 125). We think it must have got stuck in the sky. It vanished off the launch pad, and not even a parachute was seen. The launch was very impressive though.

During the evening, the motors were all prepared (2 x H-123, 2 x I-161, 2 x I-211, 1 x J-570), the avionics were installed, the igniters were prepared, and the pad was laid out ready for rapid assembly out at the launch site.

Early next morning, Hugh Gemmell arrived, with his radio transmitter, which MARS promptly "borrowed" for integration into Deimos-2 STV. Launch preparations began at about 9:00 am. By 10:15 am the launch pad had been erected, the rocket had been mated to the launch rail, the NOTAM was in force, and everything hinged on the when the TV crew turned up. The weather was fine, with the customary Lincolnshire winds cutting across the launch site, but clear sky.

The 7 igniters were all fused up, a 12 volt car battery was hooked up to the relay box to provide additional power for the multiple igniters. The R-DAS altimeter/flight computer was armed (both the R-DAS _and_ the G-Whiz altimeter/accelerometer were onboard for this flight, along with a 433 MHz tracking transmitter, and a Timer 2B for recovery system ejection).

First Iain sent up a test rocket for the TV crew. His Retro 50's style Estes Silver Comet blasted off on an Aerotech E-class motor (E15), and recovered via streamer. The flight was perfect, with a straight ascent, and recovery a short distance downwind. The film crew were so impressed, that somehow they claimed it was theirs in the programme.

The film crew got all their closeup mini-DV cameras set up close by, and were escorted to the minimum safe distance for a rocket with a cluster of the total impulse of Deimos-2 STV. Ben gave the countdown and Richard hit (and held down) the ignition button.

Basically, from examining the video footage in slow motion, it seems that one motor lit, then another, and the rocket seemed to have lifted on 2 motors (which explains why it was doing about 2 mph when it left the launch rail), as it left the launch rail, the most powerful motor - the notorious J-570 lit, and the rocket took off like Warp drive had been engaged. Then, just to add insult to injury, what seems to have been 1 or more motors airlit in short succession, and the vehicle deviated off course by about 10-15 degrees.

The rocket fishtailed its way to apogee, before giving people reason to hold their breath. Because it had only attained a third of the altitude it was supposed to, and taken a lot less time to reach its new, rather lower apogee, the timer delay was now too long, so it meant the timer would fire the ejection charge on the way down - the only question was where on the way down ?

The rocket arced over ballistically, and descended in what one might call a clean dive. Just as the flight crew were about to collapse of asphyxiation, the ejection charge fired, and the drogue and main chute (a 15 foot cargo chute) deployed and inflated nearly instantaneously about 400-450 feet above the ground, at about 80-100 mph. We noticed a few bits fluttering down nearby, which didn't look good, but the rocket looked like it had landed safely enough.

The TV crew were extremely pleased. They now had some exceedingly good footage of the launch. The flight crew were pleased as they could leave that shovel at home when they went off to recover the thing.

The upper section, comprising the payload, nosecone and the entire upper airframe, was in good condition, lying in a field, attached to the parachutes, along with the booster section, or rather, the fin canister and motor part of the booster section. Approximately 3 feet of it was missing, and was lying strewn around the field and a field adjacent to it. The R-DAS was happily beeping and flashing our the altitude, and the G-Whiz was happily flashing out the altitude. It seems, that the high deployment speed had sliced, diced and zippered the booster tube down as far as the motor mounts and fin canister. This called for a bin bag for recovery of some of the motor section !

Additionally, one could clearly see the cause of the fishtailing off course. 2 adjacent motors, an I-161 (360 Newton seconds total impulse) and an I-211 (480 Newton seconds total impulse), had not lit, causing assymmetric thrust. The igniters were retrieved, and inexplicably, two of them had not even lit.

The following day, it was discovered that another I-161 had not lit, so the rocket took off on at most, two H-123's and an I-211 (a total of 457 Newtons of thrust), and then airlit a J-570, increasing the total thrust to 1027 Newtons. The total impulse of the motors was 2040 Newton seconds as opposed to the planned total impulse of 3240 Newton seconds.

All in all, a good team effort by Ben on motors and recovery, Iain on motors, ground support and logistics, and Richard on motors and avionics/payloads, and with the great assistance of Pete and Hugh. Poor Pete was inundated with requests the whole time, and as ever was wonderful. As usual, the experience was invaluable, and each flight, the MARS launch operations get faster, smoother and slicker. Again, as usual, Ben's recovery system worked flawlessly (although the rocket happened to be in the wrong place when it worked !). Pete and Richard excelled themselves by building an avionics bay and configuring and setting the avionics in less than half an hour.

Oh yes, so how did the D2-STV flight have an unusual twist ?

Well, we learned how little thrust we could potentially fly the hybrid version on and still maintain stable flight, and we learned how low we can actually deploy the recovery system. These were far more useful lessons to learn than just another flight, albeit with a bit more tension added.

A big thank you goes to DCSL who's sponsorship made this flight possible.

By Iain Colledge