Composite Warehouse HV-ARCAS 4.5inch 75mm MMT
D'Oh, after re-reading your post, I see the altimeter has a simulation mode that "fires the light bulbs" -- which, if you'd attached e-matches would have set off the black powder and fired the ejection charge. Aha, I learned something today.
Quote from Brian C. on March 19, 2023, 9:18 pmSo many questions, so little day left.... I've seen these ejection charge tests done by Whats-his-name who does Rocket Vlogs on youtube, but I'm not sure what the procedure is. How are you tricking the altimeter to believe it's time to pop the chute? Or are you igniting the black powder manually, and if so, via what method? I don't see dangling wires in the video, so, is there some kind of remote control you've invested in? Or is a manual control method a different "program" built into the altimeter that you're able to run that gives you 3 minutes to get out of the way before it fires? Like those timers built into cameras that take a photo after a pre-determined countdown? I have yet to do any electronics in a rocket, so naturally, I am clueless.
In the past, I have simulated attaining altitude with a vacuum applied to the vent hole of the deployment electronics bay. However, the MARSA33LHD was well thought out and designed by John Derimiggio. John equipped his altimeter with a simulation mode. I displayed this in the thread with three videos. This is the one that demonstrates the Simulation Mode with the parasitic display installed. If you watch it via YouTube in High Def, you can read the display as the test progresses.
FWIW, your questions are good questions. There are several option for deployment altimeters and if you eventually progress to the point of flying with electronics, it's good to get the answers. The MARSA33LHD has a simulation mode to perform the ground tests. The Eggtimer Rocketry deployment altimeters have 802.11G wireless and a web server interface for remote control. Others have no way short of vacuum simulation. I actually like the latter because that tests the actual altimeter in more flight-like conditions. I have flown the two MARSAs in actual flights paired with PerfectFlite StratoLogger CFs (SLCF). The MARSA is unique in that apogee can be detected by barometer or accelerometer or by both. I have mine selected to use both methods for better apogee determination.
I have seen ground testing done without the altimeter at all being concerned. Many test only to insure that the deployment charge is adequate and fire with a wired system akin to a launch controller use to light motor igniters. I prefer to know that the altimeter has adequate battery voltage and current to fire the electric matches in the charge canisters.
The purpose of ground testing is to insure that the compartment maintaining the recovery laundry separates with the selected FFFFg amount. There are calculations to determine how much should be used. I believe I have links to the formula and a calculator, provided by The Rocketry Forum folks, in this thread.
Quote from Brian C. on March 19, 2023, 9:20 pmD'Oh, after re-reading your post, I see the altimeter has a simulation mode that "fires the light bulbs" -- which, if you'd attached e-matches would have set off the black powder and fired the ejection charge. Aha, I learned something today.
I learn from teaching and from teaching I learn. A lyric from my favorite Procul Harum song sums it up:
For the lesson lies in learning
And by teaching I'll be taught
For there's nothing hidden anywhere
It's all there to be sought
It's been quite a while since I last posted to this thread.
I was playing with the new Laser and I tried to etch a small (50mm) fiberglass bulkhead that I never used. I was a mazed that I was able to do so quite easily at 20% laser power. Having proved that it was, in fact, doable, I pulled out the ARCAS av-bay and engraved the bulkheads with useful information. Here's the results.
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