Close

Good and bad news...

A project log for 3DPMRS - 3D Printed Modular Rocket System

Collaborative rocket design.

mike-malukMike Maluk 10/26/2015 at 02:010 Comments

Well, it's fully assembled now. But, I'm going to have to make some changes, albeit, fun and exciting changes. Turns out I'm an idiot and have D12-0 motors, meaning they have no delay or ejection charge. This opens the door to some awesome problem solving opportunities!

It fits! So, the good news is everything has been lining up, and looks good.


AUW so far is 5.75 oz. The recommended max airframe weight for the D series engine is 14oz. So, I've got some wiggle room to add a system to deploy the chute that is completely independent from the motor. This also allows me to build my own motors (down the road, of course) that have no requirement for an ejection charge!


Well, it looks like a rocket...

The plan now is to use an ATiny85 (seeing as I have a few on hand) along with a 9g servo to deploy the chute. To simplify this I plan on using a delay system, thus avoiding any need for sensors or external input (outside of one initial input to start the clock). The way I plan to do this is by coupling the initial input signal into the relay I'm using to launch the rocket. By using a DPDT relay, I can initiate two signals of different voltages at once, 9v for the rocket igniter and 5v for the ATiny input. By mounting a small contact (most likely a pin) at the bottom of the rocket, I can allow the ATiny to receive this 5v signal when the motor is ignited. By calculating the time the rocket will take to reach it's peak, I can program the ATiny to actuate the servo at the correct time, pop the top and have it float down.

Time to get busy with eagle and get some boards cut!



Discussions