I agree that any rocket should be able to sit on the pad under ground power
all day long. If its power draw is low, you could use a 1/4" phono plug --
they're cheap, low profile, have some spring retention for wind etc while
still being easy to pull straight out, and they can handle a few amps.
It seems like we need parallel safing systems -- a 'soft' system that can
be engaged and disengaged remotely and a 'hard' system that requires some
sort of physical intervention (pins, plugs, etc). So, in the re-safing
scenario, the operator engages the soft system and then someone runs up to
the rocket quickly and engages the hard system.
-p
On Tue, Nov 10, 2015 at 1:46 PM, Paul Mueller <paul.mueller.iii@xxxxxxxxx>
wrote:
Seems that a safe/arm system may have to be at least partially dependent
on onboard power, and then the question becomes how do you make onboard
power as reliable as possible for various failure scenarios? One way would
be a ground-based charging connection much like a laptop (runs on ground
power and keeps onboard batteries charged until you disconnect it). That
way you could sit on the pad, powered up, all day long if you need to, as
long as you have gas for your ground generator! You could have a magnetic
connection like an Apple laptop, which could be fairly easily reconnected
if needed with a rotating arm. Then do your arming/safing remotely via
something like a TV remote control or even a laser pointer aimed at a
photoreceptor on the side of the rocket. It would also be smart to have
LEDs indicating the arm status of your various systems (visible through
binoculars).
On Tue, Nov 10, 2015 at 2:33 PM, Paul Mueller <paul.mueller.iii@xxxxxxxxx>
wrote:
The re-safing problem seems to be the most difficult, as the concepts so
far seem to involve pulling a pin or a rare earth magnet with a long
string. It's hard to "push on a rope" to reinstall a pin, etc. from a
distance if necessary. I'm at a loss to figure out a contraption that would
allow you to remotely arm and safe the rocket mechanically. Maybe a
rail-mounted rotating arm that would return to the same spot (assuming the
rocket didn't move during a launch attempt, misfire, etc.)...?
On Tue, Nov 10, 2015 at 10:59 AM, Pierce Nichols <piercenichols@xxxxxxxxx
wrote:
Here's a (half-baked) thought:
Make the shorting switches mosfets instead of physical switches and
drive the mosfet gates either with a single shorting plug or with a hall
effect switch. The cool thing about the hall effect switch is that you can
place it in the skin of the rocket with a small piece of steel. Then your
shorting plug become a rare earth magnet stuck to the outside of the
rocket... which can be easily pulled off with a long cord when it comes
time to arm the rocket. On the flip side, as long as there's nothing else
ferromagnetic near it, you can re-safe the rocket by tossing a small magnet
at it.
-p
On Tue, Nov 10, 2015 at 9:24 AM, Robert Watzlavick <
rocket@xxxxxxxxxxxxxx> wrote:
I have 5 opto relays I need to disable so I would need multiple
contacts - GOX igniter solenoid, fuel igniter solenoid, CDI module, servo
power, and recovery motor power. I could do a multi-pin connector and
shorting plug or go with a switch that grounds the + lead for all the
optos.
-Bob
On Nov 10, 2015, at 10:11, Paul Breed <paul@xxxxxxxxxx> wrote:
The Short across the opto with an external plug does not have to be to
ground, just short across the opto input pins. The 820 ohm resistor will be
more than enough to isolate the cpu from damage....
On Tue, Nov 10, 2015 at 7:04 AM, John Dom <johndom@xxxxxxxxx> wrote:
Actually, “Failure is not an option” is a Gene Kranz book. Not C.
Kraft.
jd
*From:* arocket-bounce@xxxxxxxxxxxxx [mailto:
arocket-bounce@xxxxxxxxxxxxx] *On Behalf Of *Nels Anderson
*Sent:* dinsdag 10 november 2015 13:48
*To:* arocket@xxxxxxxxxxxxx
*Subject:* [AR] Re: Safing of liquid vehicle
Something similar was considered, though not actually done, when
NASA's first attempt launch a Mercury capsule resulted in a four-inch
flight in November 1961. From Wikipedia (
en.wikipedia.org/wiki/Mercury-Redstone_1):
"[T]he fully fueled and powered-up Redstone was now sitting on LC-5
with nothing securing it to the pad. Various other dangers existed as well
such as the capsule's retrorocket package and the range safety
<https://en.wikipedia.org/wiki/Range_safety> destruct charges.
Furthermore, the capsule's main and reserve parachutes were hanging down
the side of the rocket, threatening to tip it over if they caught enough
wind. Fortunately, the weather conditions were favorable. Amid the
panicked
atmosphere in the control room, the launch team was unable to come up with
quick and viable options to rectify the situation. Chris Kraft, the
now-frustrated flight director, rejected several unsafe interventions,
including getting a rifle and shooting holes in the booster's propellant
tanks to depressurize them. He eventually took the advice of one of the
test engineers to simply wait out the battery discharge and let the
oxidizer boil off."
Wikipedia cite's Kraft's biography, _Failure is not an Option_, as its
source.
On 11/09/2015 02:58 PM, Ben Brockert wrote:
Only an 'unreasonable' person would carefully shoot off a vent cap
with a .30-06 when the servo-actuated normally closed vent on their
spherical peroxide rocket doesn't actuate.
On Monday, November 9, 2015, Robert Watzlavick <rocket@xxxxxxxxxxxxxx>
wrote:
I've heard similar anecdotes - has this technique ever actually been
used?
-Bob
On 11/09/2015 01:40 AM, Michael Clive wrote:
.3006 will safe it pretty good and solid.
--
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