Wednesday, February 13, 2019

Journey of the Rocket 03 - Water and Electronics do mix!

Link to full article on Facebook:

I am getting more and more interested in doing interesting things with low power rockets. It is education and robotics that led me to a rocket interest. My rocket-for-education design that started with a rocket motor of "E" power rating is now reducing and I am now designing for "B" power. The aims being:

  • to be able to launch from school grounds 
  • to take sensor readings
  • to do all-electric recovery.

I think even small rockets need to detect apogee with an altimeter to control recovery and the electronics involved are now small enough and low cost enough to work as part of a student project. The video shows - shock! horror! - a water rocket for prototype testing of an altimeter circuit. That does achieve proof of concept although I am having challenges with lightweight battery versus relatively power-hungry bluetooth module.

Journey of the Rocket 02 - Catapault(?!)

Link to article and video on Facebook:

Trying out some rocket design ideas eg air brakes by launching a test body with a catapault to get a close-up look at apogee behaviour. The air brakes do not deploy but I get some other good learning value. The tail fins seem to be remarkably effective at low speeds as in too effective. They are pointing the body nose down very soon after apogee which keeps the air flow going past the body from nose to rear which keeps the air brakes closed. I was hoping for some random airflow to catch the air brakes and help them open.

Tuesday, February 12, 2019

Journey of the Rocket 01

Rockets! These have been one small activity in the "HiTechFromLoTech" project, the idea being to use our by now sweet combo of smartphone-bluetooth-arduino as rocket and model aircraft flight recorders possibly leading to flight control. 2 students picked this up as their project at the end of 2018 and they have done excellent work with it, to the point that "Rockets" may take over as the flagship or number one activity here.

Sun 11 Nov launch day with NZ Rocketry at their launch field on a farm was excellent value for my students and me. Thanks to everyone for making us welcome. Special thanks to Alex for his help and advice and for flying our smart-phone-as-flight-recorder experiment, Thanks also to Jim Hefkey and Tristan O'Hanlon of APSS for their help and encouragement. Some findings: The lowest cost smart phone, Vodafone VFD-300, ($39 on special) did take video and record data. Data recording rate was about 15 samples per second. Our altimeter graph is close to Alex's TeleMega result. GPS results are approximate and the GPS biggest achievement is to place us on the farm. The most accurate GPS result is for walking down the track with the recovered rocket. The smart phone is working well after its flight experience. Jasmin gets a programming hero award. The day before she upgraded the user interface and data recording stopped working. On Sunday, Clinton drove while Jasmin did extreme phone programming. She got data recording up and running again minutes before the launch. Graphs are by our data analysis student Li who has been digging up her high school physics knowledge to analyse this. Our next experiment will be to try using GSM 3G cellphone data networking to send data to Earth while the rocket is in flight.

Alex loading our student instrument package into his rocket

Student instrument package in place

Data collection - smartphone records data into its SQL-Lite database

Data Analysis done post-flight - "Journey of the Rocket"