Monday, January 19, 2009

Launch Report #15

As always, click to embiggen. These are all from my dad's new high-res digital camera, so you can zoom in all the way.
Here's me putting the Lego rocket on the pad with my new 4' long 3/16" rod. I got that rod and a 3' 1/8" at a local hardware store for around $3 each under 'welding supplies.' Because it was so heavy and the booster stage fit on too loosely, it was a pain to put on and get hooked up. I wasted an igniter, the second try got the motor off.


Here's the Lego rocket / Vampire combo lfting off. It cleared a circle of snow 12" in diameter and 2" thick, down to the ice underneath.
The flight went awry. It went about 30 feet up, started to lose stability - it was too heavy - reached its peak around 60 feet up, staged, and impacted right around burnout. It fortunately turned onto its side just before impact, which allowed me to recover all the pieces except three. Three pieces broke; two slightly, but one 2x4 brick was literally cut in half by the ice.

My advice: don't fly a Lego rocket without large fins and a long body for stability, a large field with no one nearby, and a high-thrust composite motor. It was an interesting idea idea, though, and Legos *can* hold up to the stress of liftoff, if not of a crash.
This was fun. My 24mm saucer on a D12-0 staging to my Mongoose on an A8-3. It worked fairly well; the flame of the D12 reflected off the saucer's underside and made it look orange, but the saucer was a little to slow to stage safely and the Mongoose was slightly unstable, going off at a 45° angle, but it recovered safely.

A perfect flight from my Jinx on a A10-3T. It landed less than 15 feet from the pad. Note the very high peak thrust of the A10; it's putting out as much flame as a D12. This picture is slightly darkened by Picasa's processing, but it looks really cool.

I also flew my glider #2 on a B6-2. It flew great with less arcing over than the original glider, but it separated around burnout with no damage. Even with only half the normal altitude, the glider still glided for around 30 seconds, making nice sweeping circles. A flew onlooking sledders were suitably impressed; one cried out, "An airplane!"

I updated my motor impulses with data from Thrustcurve that reflects the actual rather than ideal total impulses of the motors. This knocked my total impulse flown and average impulse columns down about 10%. I flew 4 rockets plus 2 boosters on 4 flights yesterday for 51 Ns (27% F), making my totals 29 distinct rockets plus boosters on 61 motors on 51 flights for 271.92 Ns (70% H), an average of 4.45 Ns (78% B) per motor and 5.33 Ns (7% C) per flight.

The percentage of a motor class is the percentage of the way it is on the scale from the minimum of the motor class (160 Ns for H) to the maximum (320 Ns), so 271 Ns is a 70% H.

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1 comment:

mandachan said...

and you bust me up for having a picture of me playing softball on my page.