.3006 will safe it pretty good and solid.
On Sun, Nov 8, 2015 at 10:02 PM, Monroe L. King Jr. <
monroe@xxxxxxxxxxxxxxxxxx> wrote:
Just FYI I would put a vacuum on the system before I loaded propellant
to ensure the least amount of moisture in the system.
Think about on launch day say a LOX fill valve freezes. Here's something
that happened to me. I put a quick disconnect on the wrong side of the
valve and the quick connect froze and I could not get it free.
Think as if some unforeseen issue holds your count. How long can you
hold before you need to dump propellant? How would an extended hold
effect your system?
Once you have procedures consider every point a possible hold of the
count and be prepared for a shut down from that point. Procedures for
that as well.
NEVER CHANGE ANY PROCEDURE ON THE FLY! If you see something you think
you can fix DON'T DO IT! Follow your procedure and re write it. If
something goes wrong even if you can fix it do the shut down and safe
and start over.
IMO it's not safe to fix anything at all on launch day. If it's not in
the procedure ABORT!
I'm sure you are aware of most of this. Your work looks excellent and
I'm sure you will do a great job. I'm just throwing out tidbit's perhaps
some will be useful.
As you talk and I get to understand your electronics I might have some
suggestions for that. Like I said I don't trust servos or solenoids at
all. Over the years it seems they sometimes have a mind of their own no
matter what you do.
I would go pretty far to insure I had the best control over them as
possible.
I'm not saying your not. I'm just saying I know I can find a way they
can activate unfavorably in spite of your best efforts. The best
insurance is a manual valve back up but that's not always possible or
likely on a rocket.
If I had a hold and there was a servo or solenoid in the loop I would be
pretty nervous about that.
Procedures can be fun! Or you can look at it as a pain in the butt. I
will always suggest if you find it a pain in the butt. Get someone else
to do it that sees that part as fun.
-------- Original Message --------
Subject: [AR] Re: Safing of liquid vehicle
From: Robert Watzlavick <rocket@xxxxxxxxxxxxxx>
Date: Sun, November 08, 2015 8:19 pm
To: "arocket@xxxxxxxxxxxxx" <arocket@xxxxxxxxxxxxx>
Here's an idea - the power to all the "moving" parts are controlled
through opto-coupled solid state relays (Vishay VO14624AT). Assuming I
trust the MOSFET side of the SSR against inadvertent switching, all I
need to do is switch off the +3.3V that goes to the LED side of the
relays of interest:
Fuel solenoid
GOX solenoid
CDI module
Servo power
Recovery actuator motor
For added safety, since the power for the CDI and solenoids is
off-board, I can turn those power supplies off when servicing the
vehicle. Aircraft Spruce has some inexpensive mil-spec switches (Otto
T3) series that should work for the onboard +3.3V power for the SSRs.
-Bob
