Electronics for safe composite motor staging?

The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

Winston

Lorenzo von Matterhorn
Joined
Jan 31, 2009
Messages
9,560
Reaction score
1,748
Are there any electronics available for upper stage ignition which can sense the rocket's attitude and prevent ignition if the rocket isn't within plus or minus XX degrees of vertical? I know some have an altitude permissive filter, but that's less than ideal.

This excellent thread in which there have unfortunately been no posts since 2017 shows that orientation determination is much more difficult than simply reading the gyros in a MEMs sensor:

Next Generation Tilt Sensor/ Attitude Monitor

https://www.rocketryforum.com/showthread.php?140061-Next-Generation-Tilt-Sensor-Attitude-Monitor

Also, how about just a list of links to all staging electronics currently available? Know of one or some? Post the links below.
 
I think some of the Tele-series altimeters can do tilt sensing, but I don't think there are any other commercial ones.

There have been a few DIY altimeters recently, the ones I remember off the top of my head being slaak's DasAltimeter and AllDigital's Rocket Talk:
https://www.rocketryforum.com/showthread.php?144307-DasAltimeter-%96-A-homebrew-rocketry-altimeter
https://www.rocketryforum.com/showthread.php?144824-Rocket-Talk-Arduino-based-radio-flight-data

And, of course, I never miss any opportunity to advertise my in-development ArdIU project:
https://www.rocketryforum.com/showthread.php?142671-ArdIU-Open-source-flight-computer-w-ATMega328
 
Yep, the Altus Metrum *Mega boards are the only commercial products currently available that can provide this capability. Before that the only commercial board that could do it was the Rocket Tiltometer which was discontinued in 2013 iirc.

This thread on the Rocket Tiltometer has advice from Adrian on how to use his Raven altimeters to successfully program staging with those FCs to ensure some smarts are leveraged in the decision to light the sustainer motor.

https://www.rocketryforum.com/showthread.php?58947-Rocket-Tiltometer-discontinued&p=605968#post605968
 
The only issue with the Raven altimeters are the vague programming parameters and it behooves one to post ones program settings to see if others can spot any mistakes before flying. Or better yet if one has access to a flyer whose had consistent success with staging using the Raven altimeter, that would be the best way to go about it and get one-on-one instruction. Shoot, I thought I was resetting my Raven for a more accurate main chute deployment on a single stage rocket and guess what happened? No main parachute came out. I did a full system reset on the altimeter and it's been flying fine ever since. And yes, the E match was fine. Kurt
 
I have just recently flown my HP two stage using a couple of Eggtimer Quantums for stage separation and sustainer ignition. With the Quantum you can use altitude and vertical velocity as a prequalifier for ignition. To use this feature you have to have a fairly accurate sim of your rocket. The idea behind this is that if your sim is accurate you should reach a certain altitude and be traveling at a certain velocity (remember that traveling horizontally looks like zero velocity to a baro altimeter) if your stack if flying fairly vertical. Upon checking these parameters at a predefined time after booster ignition the altimeter will fire the channel to light the sustainer. My first attempt at flying this two stage failed due to a booster motor CATO and the altimeters never fired but it was due to not reaching the Launch Detect Altitude of 200’.

https://www.rocketryforum.com/showthread.php?145168-Second-Try-High-Power-Two-Stage-Success-Video
 
I have also recently flown two 2-stage flights with an Eggtimer Quantum. Neither staged - but both recovered safely. The first was shear operator error. I'm trying to fly high thrust, low impulse flights as tests ahead of a higher impulse/altitude flight. An Estes Pro Series Nike on an F79 puts staging at the bottom limit of what the Quantum allows for altitude limits, and my sim wasn't accurate enough. I thought I would be over. I wasn't. Especially as I was trying to minimize the coast period to keep the airspeed up and the total altitude down where I can see things happen. I used the data from the first flight to update the sim.

The second flight (G88-D9) drag separated at the payload bay at booster burnout. The Quantum -didn't- fire the sustainer, AND it fired the backup drogue charge at noseover. At 300'. So I'm pleased at its performance, even if I'm not pleased with mine :).
 
For the booster, I like to use motors with about a 2 or 3 second firing time, at least 8:1 thrust:weight ratio and no more than 15:1. As you found out, those high-thrust motors don't always translate into the best performance for a 2-stager... a nice steady boost works better than a short whomp.
 
I’ve been flying Smokey Sams - not really high thrust. Openrocket says about 9g. The Quantum measured 6G on the F79 flight. The stack is 760g dry. I think the challenge I set myself up was in keeping it low. The burns are about 1sec for those motors, and end about 200 feet up. With a minimum staging altitude of 300’, I’ve got to let it coast. Now that I’ve ‘calibrated’ the sim with real flight, I should get better results. And I’ve learned a lot. I’m not criticizing the Quantum, Cris. I love it. I posted to point that it correctly inhibited staging for me.


Sent from my iPhone using Rocketry Forum
 
The only issue with the Raven altimeters are the vague programming parameters and it behooves one to post ones program settings to see if others can spot any mistakes before flying. Or better yet if one has access to a flyer whose had consistent success with staging using the Raven altimeter, that would be the best way to go about it and get one-on-one instruction.

I believe that issue also exists with the *Mega altimeters as many have had difficulties configuring the staging logic without the assistance of someone who has done it successfully.
 
I believe that issue also exists with the *Mega altimeters as many have had difficulties configuring the staging logic without the assistance of someone who has done it successfully.

I agree with that, too. One either, needs to send their program to somebody who knows or latch up with someone who's flown the devices in question in staging mode. Kurt
 
Back
Top