This blog covers the day to day progress of water rocket development by the Air Command Water Rockets team. It is also a facility for people to provide feedback and ask questions.

Monday, January 21, 2008

Launcher and Booster Tests

We've had a very productive weekend this week. We completed the majority of the new Polaron IV launcher, spending about 8 hours in the workshop on Saturday.

The image below shows the state of the launcher currently. I will do a full update this week and post it on our main website that shows all the details and discuss some of the design issues.

On Sunday it was too windy to launch regular rockets and so we opted to do a number of booster test launches. We fitted a booster with a regular nozzle and launched it from our medium launcher. The main aim of the test was to see how the booster behaved in flight and how its recovery system would work. Full details of the booster will also be posted with the next web update.

The larger parachute is now finished for the Polaron IV rocket and the payload section is also well under way. With the altimeter, flight computer, and video camera, the payload section alone is worth around $300. Hmmm... I think I will add a padded nosecone extension for protection in the trial flights. This padded nosecone will be removed for the higher performance flights once the design is proven.


Unknown said...

Forgive me if you have covered this elsewhere, I have only had a chance to briefly glance through your site. (Great information though) Have you ever tried filling the bottle with plastic drinking straws to streamline the water flow. I know that high pressure water fountains force the water through an array or thin tubes to reduce the waters turbulance prior to it being forced through the nozzle. This array of tubes not only reduce the turbulance, it allows the water stream to maintain its surface tension so that there is less spray outside the water stream. I have always wondered if this idea would work for water bottle rockets. the straws would have to be glued together so that they dont fall down to the opening of the bottle. Or one could lay out a number of straws on some packing tape and roll the lot up in a spiral until they are the diameter of the pop bottle and then put them into a bottle that has had the bottom removed. Then re-gluing the bottom to the bottle... I would like to try making this array with long straws that would fit inside two joined bottles, but as it's almost -40 outside that will have to wait until warmer times.
So have you tried this?

George Katz said...

Interesting concept. No, we haven't tried that before. While trying to reduce turbulance is a good idea, I am not sure whether you would actually get a loss in performance due to the drag of the water passing along all that surface area. The edges of the straws, tape and glue also act to restrict the flow of the water and air.

You also have the added weight of all the glued straws. It doesn't sound like a lot of weight but if the rocket weighs another 30 grams, then that could be 10% of the weight of the rocket.

But you may be right in that it may produce a more streamlined stream.

It sounds interesting enough though to add to the list of things for us to try, once the static test stand is set up again.