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New Rocket Recovery System

Discussion about deployment systems including altimeters, timers, air speed flaps, servo systems, and chemical reactions.
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Jamie5335
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New Rocket Recovery System

Post by Jamie5335 » Thu Aug 13, 2015 8:01 am

Hello All,

For an extended period of time I have been very busy and preoccupied with my A-Level exams. I have also been to Japan on the World Scout Jamboree. Now all that has passed and I have a period of respite before travelling to the Peak District at the end of the Summer. Very little rocket launching has occurred but a new project has been started and development has been going on in the background.

I have started development of a new Rocket Recovery Timer- the Rocket Recovery System (RRS). This is a small PCB that deploys a parachute via activating a servo motor but it is no longer a timer. It uses a new sensor to deploy a parachute. It uses a Magnetic Field Sensor to detect when the Rocket has tipped over more that 100 degrees to then activate the parachute. This concept has been visited before and was used in Air Commands MAD (Magnetic Apogee Detector) in conjunction with there Servo Timer II. However my board is different, in the fact that is doesn’t interface with any of my older timers and uses a brand new type of microprocessor programmed in C!

Recently, I have been visiting Universities and I visited the University of York on an Electronics day on the 3rd of July and saw many awesome gadgets such as Cluster Robots and a 3D naughts and crosses game using LEDs. York were kind enough to present us all with Arduino Uno's as gifts. I had heard of the Arduino, as it was similar to the microcontroller I used presently- the PICAXE. The Arduino is a open source electronics development platform, which uses a version of C to program it. It comes with its own easy to use IDE and is a good step up from the PICAXE and its interpreted BASIC.

The Arduino System is based around an Atmel ATmega IC called the ATmega 328p. This is a raw microcontroller with a Arduino Bootloader. Microcontrollers are usually programmed through a programmer unless you have a piece of firmware in your microcontroller that allows installing new firmware using an external programmer. This is called a bootloader. I had a play at York using a shield that plugs into the top and found that it was FANTASTIC. I have therefore decided to use an Arduino in my next Rocket Recovery Timer. The Uno is rather large, and the bare IC can be used, but this is very large in a DIL package so I have decided to use a Arduino Nano. A different package of the Uno, which is smaller and includes the Voltage Regulator which means I can use the two cell lipos for power! The Nano was purchased of eBay for £1.73 along with the Magnetic Field Sensor which was £0.99.

So, how does it work? Well the Magnetic Field Sensor is called the HMC5883L. This is comes in a small package/PCB that can be plugged into a breadboard or using some female headers, a PCB. This communicates with the Arduino Nano using I2C. I2C uses 2 wires that are pulled up to +ve volts with some 4k7 resistors, that allow Serial Communication between the AVR and the HMC5883L. The HMC5883L sends data back to the Arduino in multiples of Gauss (magnetic field strength). A vector quantity as it has a direction and magnitude. When facing the north pole, it is strongly positive, when facing the South pole, it is strongly negative. Depending on the orientation of the sensor. The strength of the earths magnetic field is different. The readings can be positive or negative and are sent back to the microcontroller in the form of 2's compliment (slightly confusing if you don't do electronics). The data is send in Binary and the MSB is either a 1 or a 0 saying if the data is +ve or –ve.

Anyway, using some fancy trigonometry you can work out the angle that the rocket is at using both x, y and z readings. Using the vector from the x and y gives the angle of the rocket tipping left and right and the vector from the z and y give the angle for tipping forwards and backwards. It is awfully tricky to explain without using an animation but I am not very good at that. The code is relatively straight forward though not completely finalised. I have been doing plenty of experimentation useing the breadboard and the PCB design is very simple as there are not many connections. This project is software heavy! With the Arduino Nano, I have access to all trigonometric functions, datatypes and programming structures, unlike with the PICAXE which struggles to process non-integer numbers!

Well that gives a brief overview. I will release a more detailed overview some point soon on the forum, but for now that gives a good overview of what I am doing. Please leave some constructive criticism or some comments about the project. I would love to hear your feedback and any tips you may have.
rocket_and_HMC.jpg
DSC_0351.JPG
nano_and_HMC.png
Jamie B
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JSB Rocketry
Website: www.jsbrocketry.webs.com
Youtube: https://www.youtube.com/channel/UCczlD-uBjlYdJyBFEfuCEbg/feed

Jamie Bignell,
jamie.s.bignell@gmail.com
Somerset UK

"The important thing is to know how to take all things quietly" -Michael Faraday.

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Tim Chen
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Re: New Rocket Recovery System

Post by Tim Chen » Thu Aug 13, 2015 8:40 pm

Nice project! Do you think that you can track the heading of the rocket through the flight? Maybe record the spin and stuff? That would be cool.


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Team Seneca
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Re: New Rocket Recovery System

Post by Team Seneca » Fri Aug 14, 2015 12:53 am

The Magnetic Apogee Detector (MAD) was invented by Professor Robert Galejs of MIT over 15 years ago. It was quickly refined and sold by Aerocon Systems. Katz (as usual) has been using a knockoff of an existing design, except he didn't even build it. It was a clone that someone else sells called uMAD.


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Jamie5335
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Re: New Rocket Recovery System

Post by Jamie5335 » Fri Aug 14, 2015 6:12 am

Tim Chen wrote:Nice project! Do you think that you can track the heading of the rocket through the flight? Maybe record the spin and stuff? That would be cool.
Hello Tim,

Thanks for the compliment. Once I have mastered the system, yes the Arduino can log data and save it to EEPROM memory which can be accessed. So the simple answer is yes, spin and heading could be logged. That is actually a really cool idea that I am going to try and research further and implement in the future. I have got the basic concept nearly mastered- but that is an excellent way of pushing forward the project and the idea of logging spin and the tipping bearing using electronics hasn't really been explored using a water rocket yet! (as I know of!) How exciting! :D

Thanks, Jamie B.


JSB Rocketry
Website: www.jsbrocketry.webs.com
Youtube: https://www.youtube.com/channel/UCczlD-uBjlYdJyBFEfuCEbg/feed

Jamie Bignell,
jamie.s.bignell@gmail.com
Somerset UK

"The important thing is to know how to take all things quietly" -Michael Faraday.

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Jamie5335
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Re: New Rocket Recovery System

Post by Jamie5335 » Fri Aug 14, 2015 6:16 am

Team Seneca wrote:The Magnetic Apogee Detector (MAD) was invented by Professor Robert Galejs of MIT over 15 years ago. It was quickly refined and sold by Aerocon Systems. Katz (as usual) has been using a knockoff of an existing design, except he didn't even build it. It was a clone that someone else sells called uMAD.
Hello Team Seneca,

Ah, it is interesting to know a little history about the Magnetic Apogee Detector.

Jamie B


JSB Rocketry
Website: www.jsbrocketry.webs.com
Youtube: https://www.youtube.com/channel/UCczlD-uBjlYdJyBFEfuCEbg/feed

Jamie Bignell,
jamie.s.bignell@gmail.com
Somerset UK

"The important thing is to know how to take all things quietly" -Michael Faraday.

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