[AR] Re: magnetic apogee sensor

  • From: Ben Brockert <wikkit@xxxxxxxxx>
  • To: "arocket@xxxxxxxxxxxxx" <arocket@xxxxxxxxxxxxx>
  • Date: Sat, 18 Jul 2015 13:40:56 -0400

There's a lot of them out there!

https://www.apogeerockets.com/Electronics_Payloads/Altimeters/PerfectFlite_StratoLogger_Altimeter?cPath=52_192&zenid=82e9eb46ba716a7b27c5ef85e148bd74

$59. No soldering. With screw terminals you attach a battery and up to
two igniters (up to a crazy 10A!) for deployment, one goes off at
apogee and the second goes off close to the ground, known as 'dual
deployment'. Typically either you just deploy the parachute at apogee
for relatively low altitude rockets, or you do a small drag device at
apogee (a drogue or simply separating the rocket into two pieces,
attached by cord) and then a main parachute near the ground.

Also logs apogee height and beeps it out.

$86:
https://www.apogeerockets.com/Electronics_Payloads/Dual-Deployment/EasyMini?zenid=82e9eb46ba716a7b27c5ef85e148bd74

Different manufacturer, same idea, still no soldering, and this one
you can directly plug into USB after the flight to download logged
flight data.

There's no way a metal ball in a cage can give accurate apogee
deployment for any significant altitude, it's just not physically
possible.

Ben

On Sat, Jul 18, 2015 at 1:11 PM, John Dom <johndom@xxxxxxxxx> wrote:

Ben Brockert wrote on 180715:

what's the use case that requires a magnetic apogee sensor? There are plenty
of barometric or accelerometer-based apogee sensors on the market, some
incredibly small, and they're quite reliable.

Plenty and on the market, I only need one! It need indeed not be a magnetic
apogee sensor circuit capable to fire a squib or drive a servomotor. I am
just exploring cheap reliable sensor actuator circuits on the market ready
for use.
Even Apogee does not have such and the item of Aerotech costs 150 USD and is
an RDAS dongle . So should you know better, please mention a sensr/PCB type &
company producing apogee actuators, NOT REQUIRING advanced (to me)
electronics circuitry design and tedious risky soldering jobs.

As far as I am slowly finding out, barometric, accelerometric or even such 3D
sensors record or transmit trajectory data like apogee which are only useful
for post-flight analysis. Giving nice graphs to point out when apogee
occurred in time, later on. But AFAIK, they are not actuators which can fire
the squib near apogee time. Most rocketeers I know, familiar with nineties
prints and code like RDAS report nice altimeter graphs. But their parachute
squib is fired by... a timer! Apogee time preset by trajectory simulation
software. Reliable?

So far the only cheap real time apogee actuators I came across are ingenious
metal ball or micro ball tilt sensors. No µprocessor fuss required. If they
are reliable I still have to find out next month or so.

jd




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