JSB Rocketry

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Rocket Recovery Timer 2

What is it?

The Rocket Recovery Timer 2 is designed to deploy a parachute on a Water Rocket to safety recovery it back to earth without the rocket hurting anyone. It also makes sure that your rocket can be re-used and doesn't break when carrying heavier and more precise payloads.  

The RRT2 was designed to be user friendly and to allow the user to program the time delay (until the parachute is deployed from launch) and Servo Positioning. It was also designed to fit in the Side Deployment system to deploy a parachute on a Water rocket. If you don'y know much about the Side Deployment system then visit this link to build one:

Can I buy one?

A lot of hard work and personal time was given up in the design and manufacture of this product. If we get enough interest in the timer then we may start to sell them in a batch production format.  Presently we have no timers ready to sell. It you personally want one then feel free to email at [email protected] and we can reserve one for you so that once more timers have been all finished and ready for selling you are guaranteed one! We are not quite sure of the price, but it will not break the bank. Again, if you want more details then email us.

How does it work?

The Timer is based around the PICAXE 14M2 Microcontroller. This is basically a mini computer. We at JSB Rocketry have written the code for the PICAXE in BASIC that enables it to be used in this configuration as a Rocket Recovery Timer! This code is downloaded to the PICAXE and interpreted. The timing and positioning of the Servo can be changed via variable resistor which gives an analogue value hence the need for a fixed voltage input as this value will change as the input voltage decreases or changes. However, simple easy to understand steps on how to change the delay and servo positions are explained below and the push to make PCB mount switch can aid with the setting of different parameters. 

Four LEDs are included on the board, each one telling the user which state the timer is in. There is a Power LED, then two LEDs to show the user if they are setting the timer delay or the servo positions and also an armed LED. All values are saved to the EEPROM memory of the PIC which is non-volatile meaning that the saved settings can be accessed as soon as the timer is powered up. The RRT2 also differs from the RRT1 via having an on-board piezo which acts as a auditory means of knowing when the timer is armed. A PCB mount slide switch is included to allow an easier means of turning on and off the timer. The PIC can be reprogrammed without unplugging it from the IC socket as a programming socket can be connected to the pins to the right of the board (more details below). The timer can be triggered by either a broken wire or a G-Switch, either one of these triggering will start the delay automatically meaning there is no need to set a preference- these are connected via a internal OR gate in the PIC to the trigger input.  

How do I configure the settings?

To set the Time Delay:

To set the time delay the potentiometer is turned to anywhere in this range (see picture below). This image shows the top of the potentiometer for ease of viewing. The timer is then powered on. Once the timer is powered on the user turns the centre of the potentiometer to the number of seconds that they want the delay to be. In this case it is a delay of 4 seconds. Each notch on the potentiometer is a second as seen here. The program button is pressed and the time delay LED flashed the number of seconds including the 0- which can be confusing!

Link to Simulator: http://www.polyplex.org/rockets/simulation/

To set the Servo Positions:

When the user wants to set the two positions of the servo, the centre of the pot is tuned to anywhere in this range (see image below) and the timer is powered on. The user can then use the potentiometer to turn the servo to the position they want it to start in. Once they are happy with that, the program button is pressed and the servo LED flashes indicating that the starting servo pos is being set. The user then does the same with the potentiometer to set the end position. Note that by skipping notches on the POT the servo will move in larger, less fine steps. The program button is then pressed, saving these values to EEPROM memory and the timer can be switch off.
To use the timer for Launch mode:

The user can use the timer for recovering the rocket. Putting the potentiometer in this range (see image below), and turning the timer on will put it in the launch phase. The armed LED has turned on and the timer waits for the G-Switch to be triggered. In this case shorting it out with a piece of wire simulate a launch and then 4 seconds later the servo is moved from the start pos to the preset end pos. A default 5 seconds later, the servo moves have to the start pos and the time can then be turned off ready for the next launch. 

Note the timer can be triggered by either the Breakwire or the G-switch. If the timer is turned on and the wires are attached together then the timer will assume that the user wants to use the Breakwire as a trigger option. If the timer is powered in the launch mode and the wires aren't together the timer will use the G-switch to detect launch. This just means that if you want to use the Breakwire. Twist the wires together before powering on the timer. A Breakwire should be used for low G rockets as the G-switch may not trigger. An example would be a foam rocket. Any fullbore rockets would use the G-switch.

How do I power it?

The Timer can use up to 13 volts. We tend to use double cell, 7.4 volt Lipo batteries. The RRT2 differs from the RRT1 because the RRT2 has a Voltage regulator on-board which makes sure that a constant supply of 5 volts reaches the PIC even if you use a power supply greater than 5 volts so a 9 volt battery could also be used. The timer simply controls the timing and positioning of a Servo Motors movement. Because of the 5 volt regulator it isn't recommended that a single cell lipo is used as this would change the ADC values. A 2 cell should be used for optimum performance and it is small and light enough to mount on your rocket.

Any Questions?

We at JSB Rocketry are happy to answer any of your questions regarding the timer. The Operation, the Manufacture and Availability of the RRT2 are all open to discussing. If you want to just leave any comments or constructive criticism in the form below please feel free.

Thank you for contacting us. We will get back to you as soon as possible
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