Please tell me what the final heights of both the Long Brothers' and Art Attack's rockets were. Inquiring minds want to know!!!

-- Jeff Collings (jwc59@home.com), January 25, 2001

Answers

It seems that both rockets ejected their payloads about halfway up at around 1000 feet. The rocket bodies themselves continued up another 1000 feet or so.

This is because of a gaffe with the accelerometers that nobody caught. See my post below on the subject. =)

Thomas

-- Thomas (trh1@cris.com), January 25, 2001.

The two rockets were fitted with altimeters. Our reading was somewhere around 1200- 1500 ft. The long brothers altimeter didn't survive the crash so there was no reading. If our egg would have stayed intact it would have been a default. Also, our altimeter was supposed to set off a charge at the point of the highest arch to set off the parachute....It never shot it off at the right time correctly. It deployed the parachute maybe only 10 feet from the ground. All that aside...it was a great battle and lots of fun with the Long Brothers and the outraegeous crew of Junkyard Wars!

-- Duane Flatmo,Art Attack (flatmo@humboldt1.com), January 25, 2001.

So was your ejection charge wired up by the same people who wired up the igniter? Just kidding!

Was the altimeter in the nosecone with the egg? If so I'm surprised it was damaged.

On another note, I noticed that the aluminum on the cone rocket was deforming significantly during the early stages of acceleration. I wonder if the ring that was suggested too late would have helped to stabilize it.

-- Michael (Canadian P.Eng.) (michael@mks-tech.com), January 25, 2001.

I think those were definitely accelerometers..

The only two types of altimeters I've ever seen are:

1) radar altimeters. Which means you need a radar transciever. Those thingies used on the show sure as heck aren't radar altimeters.

2) air pressure altimeters. These require a static pitot probe to detect air pressure, but I don't see it on those devices used on the show either.

So I think it stands to reason that those electronic devices George and Cathy handed out to the team are accelerometers-- You can actually use acceleration values detected by those things to calculate speed, and if you know the speed, you can calculate altitude over time. :-)

Thomas

-- Thomas (trh1@cris.com), January 25, 2001.

Accelerometers vs. altimeters also explains the "premature" ejections, assuming the devices were designed to close a switch when the readings went to zero.

As long as the devices were just being handed around the work areas, the sensors would have been measuring 1 g. At launch, the measurements would have been 3, 4, or more gs. As soon as the motors cut off, the rockets were in free fall -- zero g -- even though the rockets were still moving upward.

Accelerometers were definitely the wrong choice for ejection initiators. A simple timer would have been better, or a remote switch activated from the ground.

Great show, nevertheless! The highlight of my TV week.

-- John Riess (jriess@swbell.net), January 25, 2001.

Art Attacks 1150 ft by the altimeter, Long Brothers ? Altimeter destroyed! And as far as the accel vs altim question. The devices we used are very sophsiticated computers. They have a accelerometer and a barometric altimeter on board. A single chip computer reads the accel and waits for positive g force above 1 g for a 1/4 second. At that point it starts recording g forces and baro readings. At the same time of recording the g force it calculates the velocity of the rocket. It is this velocity that the device uses to determine peak altitude. They have been around a while and are fairly reliable. (except in this case, I have not been able figure out why it deployed 10 ft or so above the ground.) Timers are great for backup but you need to know within +/- 2 seconds when peak alititude is going to occur in order to use them. If you miss you might as well not deploy at all or have a strong chute and well designed harness.

-- James Tucci (Jtucci@archion.com), January 29, 2001.

Can you given me some infomation on rockets

-- Mark Robinson (mark@durrd.freesrue.co.uk), February 20, 2001.

Mark R. Search for Tripoli Model Rocketry Club. Their site will load you up with links and info.

-- Waddy Thompson (cthomp3851@aol.com), February 20, 2001.