Sunday, February 26, 2012

Stiga flight 2 - to 95km by Armadillo Aerospace



Recovery on this flight was less than optimal, but it is great to see the rocket performing as needed for spaceflight.

The footage from about 3:30 until reentry shows really cool micro-gravity and a lack of atmospheric drag. One can see a parachute just float around, along with small particles, the nosecone, and recovery lines. This is the look (and silent sound) of space!

A recovery failure appears to occur at 4:59, with the loss of the nosecone and ballute. Clearly spaceflight is hard, and takes practice to get right. Even with minor problems like the ballistic recovery, I consider this flight highly successful. With the loss of this drogue ballute, the main 'chute was destroyed as well. With the rocket now aerodynamically stable again, an high-speed impact was inevitable.

The best part of the video is at the end when the rocket comes in ballistic (and nose-down) for a crash landing. Yes it is sad that the rocket was damaged, but it scores very high on the cool factor nevertheless. It falls very fast, supersonically it would seem. The rocket then lands extremely close to the launch pad. It is good that footage was recovered and no one was harmed by the crash-landing at the end.

"The video and subsequent hardware analysis showed that when a coiled rope extended and created a jerk load, the ballute broke a strap that was meant to retain it until the main was released.

After the ballute left the vehicle, the rocket fell nose-down the rest of the way. The main parachute also departed with haste as the rocket entered the thicker atmosphere. Once the rocket gets below the clouds it provides a good view of the spaceport runway and the gravel mine southwest of the vertical launch area.

Telemetry was regained briefly on the way down as the rocket came back within range. It sent some information on event timings, but unfortunately does not send a latched apogee altitude. Apogee was estimated from the position and velocity curve of the last data received, about 10 seconds before the end of the burn, plus main engine cut-off time and apogee time from the onboard video. The best match to the data is at 94.5km above sea level.

From launch control we heard a sonic boom, shorter than the last flight's, followed by the noise of a rapidly falling rocket. The rocket was spotted, and some of us watched as Stiga impacted the ground at 205 meters per second roughly 750 meters from the launch site. This represented kinetic energy of around 5 megajoules. Everything on the rocket was destroyed, except the fins and engine, which were last to hit the ground and were quite overbuilt."

The nosecone and ballute were recovered about nine miles away! From the picture below, the size of this rocket becomes clear. It is a huge nosecone, and that is not 1 inch kevlar strap as I had suspected, but rather some really beefy 2+ inch strap. They clearly built it up and it still failed! The dynamics of spaceflight are particularly demanding.

Here are a few images from the website:




I am particularly interested in the ballute used for recovery:





I had previously noted that they would be better off going with a rocketman drogue. While I still suggest trying this, it is clear that the ballute is working fine and the real problem this time was a failure in the attachment point. This ballute will possibly be used on the next flight, a new rocket designed to fly to 125 km.

Here is more information about the flight:

Stiga Flight 2

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