2009 Project – Cradle Boosted Rocket—>launched

Well, we tried it. As an engineer I’m very familiar with the old saying “Back to the drawing board”, and that’s where I ‘m going.

This cradle rocket concept can only work if both motors ignite within milliseconds of each other while the rocket is still on the rail. Because of the waiver’s ceiling of 12,000 feet, I had to use J motors in the booster and both were required to get the speed for stability before leaving the rail. It was designed to accomodate K700’s so there might have been a different outcome, but I doubt it.

All 6 electronic modules worked, and believe it or not are all usable again. One thing learned was you can ignite the sustainer from the booster as long as you do it under thrust. The DC20 was having trouble picking up the WAAS because of the dense cloud cover

Both J350’s in the cradle fired (see picture #2 in the series below, you’ll see a bit of flame in the left motor and smoke in the right motor).

Picture 3 shows only the right motor in full burn. After it leaves the rail, it starts to bend left, then when the left motor finally turns up the wick, it bends back right. (see picture 4) You’ll notice the black pair of fins on the sustainer always facing the camera. Fortunately it kept bending so that it went away from the crowd at the LCO table.

1.1 second after 1st movement of the rocket, the timer in the cradle ignited the sustainer and separation occured.

The cradle fell into the earth on the left side of the trailer, jamming the nosecones, so when the deployment charges went off (via dual PML/MW CPR’s), it was too tight to separate. (note the backup main charge did not go off).

The sustainer hit the ground on the right of the trailer and broke the tail can off at the top of the motor (the retention held at the top). Though the nose cone hit first breaking the tip off leaving the GPS exposed, I think it was a fairly flat strike, like an airplane pancaking in, as one fin broke off and the sections separated under the shock, both chutes deploying. You can see the drogue shock cord stretched out as that section is flying to the right.

However, none of the 4 charges in the sustainer avbay went off. They were connected to two MW RRC2-mini’s. This may be because the rocket never reached the initialization threshhold, or more likely my 8 second mach delay. Before 8 seconds went by, the avbay was laying on the ground so it may have thought it never left.

All three nosecones were damaged beyond repair, but the tubing stayed intact (except for the sustainer tail can).

More comments after the picture sequence…

A very short movie:
http://www.telerover.com/rockets/CR/GoH_Launch.MOV

My goal was to make a multi stage minimum diameter rocket design that was fairly short(and light for carrying as I have a bad back), and had all the deployment options, unlike my K700 to K700 “The Twins”.

Unless someone can show me a reliable, repeatable method of lighting two motors simulataneously, the dangers of asymetrical thrust is too great to risk people getting hurt and the amount of work it takes to build these is too extensive.

If I do this again, I think putting deployment electronics and chutes in side pods on the booster, with a central motor would be the best alternative. Still thinkin’….