Troy:
Yeah, I just got a 4s 850 mAh (32 Amps burst) set that is not much bigger
than my thumb; things battery have improved some of late....
Bill
On Thu, Oct 8, 2020 at 5:38 PM Troy Prideaux <troy@xxxxxxxxxxxxxxxxxxxxx>
wrote:
Bill,
Responding to this specific concern: you can power the solenoid valve
from a/or some dedicated battery/ies for that task. Utilising LIPOs, you
can look for the smallest 3s with the highest C (burst) rating.
In fact, I’d be surprised if a suitable 2s close to the valve/relay/FET
(re: minimum voltage drop) wasn’t enough to reliably open one. Something
like one of these:
https://hobbyking.com/en_us/turnigy-nano-tech-300mah-2s-45-90c-lipo-pack.html?queryID=9f4e3e19b8f282355fcd7d3c995d57db&objectID=47473&indexName=hbk_live_magento_en_us_products
0.6ah x 90C = 54A available burst from a tiny battery.
I have NOS solenoid valves and these batteries and can do some testing if
anyone is curious.
Troy
*From:* arocket-bounce@xxxxxxxxxxxxx [mailto:arocket-bounce@xxxxxxxxxxxxx]
*On Behalf Of *William Claybaugh
*Sent:* Friday, 9 October 2020 10:11 AM
*To:* arocket@xxxxxxxxxxxxx
*Subject:* [AR] Re: Vibration Tolerant Pneumatic Valve
Wyatt:
I should respond to your NO suggestion: the issue I see is that these
valves typically require about 8 amps at 12 volts to actuate, that is a lot
of internal power if it is coming from on-board batteries for, say, an hour
before launch plus powered flight.
In addition, a power failure means the payload comes off the rocket.
Obviously an external power source and switching to onboard power just
before launch will help w/ the first issue at the cost of further
complexity. The second issue is more a matter of preference, I think: with
a NC valve the payload rides the rocket into the ground if the power
doesn’t come on.
Bill
On Thu, Oct 8, 2020 at 2:06 PM Wyatt Rehder <wyatt.rehder@xxxxxxxxx>
wrote:
A simple solution might be to use a NO solenoid, as you might be able to
spice up the actuator a bit and get the electric closure force stronger
than the spring return force. That might be enough to keep the leaks away.
In a similar vein, are you able to change the orientation of the solenoid
to the vibration? Or is the vibration axis pretty random.
Next option (which I haven't tried) they do make rotary solenoid
actuators. Which you could pair with a ball valve. That should be pretty
immune to vibration. But I can't attest to how reliable they are.
-Wyatt
On Thu, Oct 8, 2020 at 9:59 AM William Claybaugh <wclaybaugh2@xxxxxxxxx>
wrote:
Testing shows that the Lake Axial Solenoid valve in my pneumatic payload
separation system is leaking at 125 psia despite a 1000 psia rating (two
valves tested, both leaked); the leak is through the valve and caused the
latchup of the payload to the vehicle to fail within an average of four
minutes. Additional testing on my vibe table showed latch failure in less
than one minute in ten tests.
Can anyone suggest a solenoid valve good for at least 250 psia and
unlikely to leak under vibration?
Alternative suggestions to using a solenoid valve are welcome.
Thanks,
Bill