A count down

4/20/2015

2 Comments

Getting ready to launch a rocket.

Attaching the leads

ignition

Rocket on the way. Fun stuff.

2 Comments

Linda

4/20/2015 11:55:55 pm

So, how far away did it land?

Keith

4/21/2015 01:47:49 pm

Hi Linda,

Remarkably, not that far away, maybe 25 yards?

There are a number of factors involved here, and I will try to explain. Given that we were launching on a school ball field, we had to land pretty close to the launch pad or risk ending up on a neighbor's roof or in the middle of the league soccer game going on right next to us.

It was pretty windy, which was a concern. If you notice, the launch was set at an angle just to the right, into the wind. This helps as the wind will try to blow the rocket as it climbs. However, there is a second bit of physics involved. The rocket is aerodynamic at the top, but a crosswind will blow on the fins on the bottom, thus putting the rocket's position actually angled into the wind. The engine is producing thrust parallel to the rocket, so the angle makes the rocket actually fly into the direction the wind is coming from.

So, the rocket was essentially flying into the wind and over the soccer game. And then the second key. We did not use a parachute but a streamer to slow the descent. A parachute would have taken it way off into the nearby housing plan, but a streamer allowed it to have a reasonably slowed descent without too much wind blowing it away.

Add all those physics vectors up and you can fly a rocket in fairly heavy wind and it will land darn near where you shot it up from.

A count down

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