Big Update! (Patreon)

Hey there! Have you wondered why I haven't posted anything for a month? Me too! I'll be working on getting more regular updates out, just had a bit too much on my plate for a bit. Without further adieu, here's what's been going on.

TVC Static Fires:

We had a second static fire on June 23rd. After reviewing lots of data and working for weeks on developing an offline simulation of the rocket's behavior under thrust, I concluded that the model I was working with was accurate enough(it was). I performed a bifilar pendulum test(correctly) and then used that to calculate the inertia of the vehicle(incorrectly). Not knowing I did my math wrong, I headed out to the test site and performed the test: https://www.youtube.com/watch?v=TTf8HQ941RU

After seeing the poor results of this test, I went back, double checked everything, and found an error in my inertia math - an extra set of parenthesis. I re-did my math, got a different value, and tuned the simulation to that value. Here's where the cool part comes in. Scout, Relay, Echo - all of these vehicles have fairly similar masses. To see if I got the inertia correct in my simulation, I plugged in the PID values from the Relay F2 flight. 

To explain, doing this should give me a fairly close flight profile to Relay F2. Though the inertia of the current build of Scout and the past build of Relay are certainly different, they should be close enough to return fairly similar results (if my math on the vehicle inertia is right)... and it was! The offline simulation closely matched the real, in-flight data of Relay F2! This is something I should have done for the second hold down test in hindsight, and would have allowed me to catch my error sooner, and without burning a motor. 

Here's footage of the newly tuned Scout V1.1: https://www.youtube.com/watch?v=u6gw6bdgeeM

Signal Avionics:

Progress with the Signal system is still on schedule! The photo above is of the next revision on the flight computer(everything is still un-routed of course). I'm sending out for a print of the board tomorrow. Upgrades include a screen to show data and a simple UI for programing, a micro SD card slot, a few buttons to navigate the UI, another pyro channel, a simpler overall wiring scheme(no more TVC breakout), a second switchable power supply for fin and TVC use(can be turned off without fins to save power), and many other small changes like component sizes(0406 instead of 0805), adding another timing crystal for the IMUs DMP, etc. The only downside, is there will be less LEDs, a decision that will haunt my dreams forever.

What's next?

This week I have a few things on my plate. The first is to get this new revision of Signal sent off for printing. In addition, I got some slightly troubling news this week that I may have a problem actually selling the system internationally, potentially nationally as well. I'll be going through ITAR, EAR, and DDTC regulations to see what I can find out. I was not under the impression that what I am building violates any of these regulations, but have heard from a few folks that it may - the safest option is to do my homework very thoroughly here.

Otherwise, I'll also begin work on an emergency chute deployment system for Scout V1.1. It's not responsible to continue flying rockets without parachutes, which means I need a better deployment system than mounting them radially. I'll be storing an emergency set of parachutes up at the top of Scout. They'll deploy out the top of the vehicle in the case of an off course trajectory, computer error, etc - a real flight termination system! Side note, this feature (orientation triggered aborts) will be part of the Signal system as well.

As always, thanks for following along - more to come soon!