I am seeing pretty much consensus, with convincing reasoning, for choosing a
very different flight computer for redundancy. Based on my experience with my
3” diameter Start Walking III rocket, I would like to argue that there are
benefits to using the same flight computer.
If the flight computer is very reliable for the needs of the rocket then the
much more likely source of problems will be from sources external to the flight
computer that change with each flight. Hardware problems include malfunction
of electric matches or breaks in the wiring. For some of us (ok, speaking for
myself), the biggest source of problems I had with deployment could be
classified as operator error. In particular, my experience was that having two
very different flight computers can add a whole set of other potential errors.
For instance, I wired wired one ejection charge into the main terminals and the
other (accidentally) to the apogee terminals. I also found it much more
difficult to set up multiple diverse flight computers on the electronics
platform (the 3” diameter makes space an issue). So, I settled on using the
same flight computer (Altus Metrum Easyminis) for both primary and redundant
deployment control. Here are the advantages:
1) Using the same altimeter allow me to mount them back-to-back on my
electronics platform which made the position of the terminals for the primary
and redundant ejection charge wiring identical, so less chance of connecting
them incorrectly.
2) User interface including method for setting parameters and beep sequences,
is the same for both altimeters so less chance of confusion.
With this setup, I have not had any parachute deployment failures in SWIII for
many flights. The bottom line is that I have found that keeping things simple
and knowing your equipment very well has a lot of value in reliability.
On Mar 22, 2021, at 7:25 AM, Michael Kramer
<mike@xxxxxxxxxxxx<mailto:mike@xxxxxxxxxxxx>> wrote:
not to get all Kevlar vs nylon but...
Just checking peoples philosophy, if you have a redundant altimeter, better to
have;
a) 2 identical ones (Stratologger CF - Stratologger CF )
b) 2 different ones, each from different manufactures (I.E. Stratologger CF -
RRC3)
c) 2 different ones, same manufactures (I.E. RRC2 and RRC3)
d) doesn't matter any combination works
Mike Kramer
On 3/20/2021 11:00 AM, Chris J Kobel wrote:
Richard,
Darn it, left work at 3:30 and missed it! I had the website up and refreshing
and everything.
Thanks for the heads up, I’ll just have to keep trying.
Chris
From: roc-chat-bounce@xxxxxxxxxxxxx<mailto:roc-chat-bounce@xxxxxxxxxxxxx>
<roc-chat-bounce@xxxxxxxxxxxxx><mailto:roc-chat-bounce@xxxxxxxxxxxxx> On Behalf
Of richard dierking
Sent: Friday, March 19, 2021 8:06 PM
To: roc-chat@xxxxxxxxxxxxx<mailto:roc-chat@xxxxxxxxxxxxx>
Subject: [roc-chat] Re: PerfectFlite Stratologger CF Altimeters
Well, hopefully Chris got my email and placed his order. Perfectflite Direct
had CF's in stock for a couple hours. Now showing out of stock again. :-(
On Mar 19, 2021, at 2:01 PM, Chris J Kobel
<chris.j.kobel@xxxxxxxx<mailto:chris.j.kobel@xxxxxxxx>> wrote:
Thanks Mike and all,
I just might have to try that!
Chris
From: roc-chat-bounce@xxxxxxxxxxxxx<mailto:roc-chat-bounce@xxxxxxxxxxxxx>
<roc-chat-bounce@xxxxxxxxxxxxx<mailto:roc-chat-bounce@xxxxxxxxxxxxx>> On Behalf
Of Mike Riss
Sent: Friday, March 19, 2021 1:46 PM
To: roc-chat@xxxxxxxxxxxxx<mailto:roc-chat@xxxxxxxxxxxxx>
Subject: [roc-chat] Re: PerfectFlite Stratologger CF Altimeters
Chris,
Seems like waiting for SLCF's to become available is like hunting for snipe ;-)
In the meantime, I'd recommend trying Eggtimer's Quantum. Pick up an Apogee
and a Quark while you're at it.
Mike
On Friday, March 19, 2021, 12:47:18 PM PDT, Chris J Kobel
<chris.j.kobel@xxxxxxxx<mailto:chris.j.kobel@xxxxxxxx>> wrote:
Just wondering, anybody know why PerfectFlite Stratologger CF Altimeters have
been unavailable for so long?
Thanks
Chris Kobel
(looking forward to see you all April 10!)
