Greg Klein's Blog

Balloon Parachute Test

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Okay, so my internship is done at Sun Labs, and I’ve got about 3 weeks until I’m leaving for Santa Cruz.

In the time that I’ve got, I’m working on a project with my friends, Tim and Alex. We’re planning on sending a high altitude weather balloon into near space (roughly 90,000 ft).

The parachute arrived in the mail the other day. It’s 5 ft wide and designed for rockets. We weren’t actually very sure about the size, so we decided to test before the actual flight. We’re pretty sure our payload will be about 5 pounds, so we tried to figure out how fast a 5 pound weight would fall with the parachute attached.

So how do you test a parachute?

Well, our first thought was to drop it from somewhere high. So Alex climbed up on the roof, and we dropped the thing.

Unfortunately, the roof wasn’t as tall as we would have liked it to be, and the parachute did not inflate. Not terribly useful for finding descent rate.

So we thought about the problem for a while, but couldn’t find any taller places from which we could drop things.

The only other option was to test horizontally rather than vertically.

The idea is as follows: we attach the parachute to the back of a car and drive. When the parachute pulls on the car with a force of 5 lbs, the speed at which the car is traveling is the terminal velocity of our 5 lb payload and parachute.

So, in lieu of a proper scale for this sort of thing (likely a fish scale), we found a kitchen scale and made that work.

Tim and Alex got into the car and I chased behind to make sure the parachute got airborne and didn’t drag too much.

When the scale hit 5 lbs, Tim stopped accelerating and noted his velocity. We measured a terminal velocity for a 5 lb payload to be 12 mph.

More to come on the payload and other details.

Written by gregklein

September 1, 2009 at 8:07 pm

Posted in balloon

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  1. Dumb students


    November 11, 2010 at 6:12 am

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