Updated February 20, 2006

ScienceMan Neat Idea - Rocket Engine Impulse Lab

I'd like to share a truly amazing lab with you for measuring impulse. Wouldn't it be great to be able to measure the thrust of a rocket engine? Well you can! Just grab your science interface, a force sensor, a few different rocket engines and you're ready to rock!

Pasco makes a great rocket bracket that attaches directly to the force sensor. Watch the following video carefully (QuickTime, 2.3 MB) and you'll see how simple the set-up is. The rocket in the bracket is fired, sending force data to the portable 500 interface. For comparison sake, we fired off three rocket engines, a "D", "C", and a "B".

When the data is brought back to class and downloaded into DataStudio, you can clearly see the force of the engines over time. The following graph show the "D" and "C" engines;

What's really slick about the software is that it will allow you to calculate the area under the curve, automatically calculating the impulse of the engine!

Try not to make the same bone-headed mistake I did... I forgot to tare the force sensor before firing, so you can see the tracing started above zero. Students compensated for this by calculating the area of the rectangle "underneath" the rocket firing data, and subtracting it from the total provided by the software (see the inset numbers on the graph). They found the impulse of the engines was very close to what was advertised on the packages! Cool!