[Balloon-makers] FW: micro-solenoid valve

[Noah Forden]

I lied, it was April 1990.  See attachment

  _____  

From: Kyle Kepley [mailto:kyle at passfire.com] 
Sent: Saturday, December 27, 2008 12:45 PM
To: Noah Forden; balloon-makers at taleos.com
Subject: re: [Balloon-makers] FW: micro-solenoid valve


Hi Noah,

 

Thanks for the info.  I tried looking up your Balloon Life article in the
online archives, but they only go back to 1995 unfortunately.  My first
burner attempt was made using a valve similar to the one you linked to.
Here's the Swagelok valve I tried:

http://www.swagelok.com/search/product_detail.aspx?part=B-1GS4

 

I just put a servo in front of this and wired the servo arm to the valve
lever so that it would pull the valve open.  My design had other problems
with leaks though, so I'm going to rebuild the whole thing and try solenoid
valves this time.  I was using all compression fittings, which seem to be
very prone to leaking.   What is the best method to use for the plumbing?  I
have to keep the gondola construction to around 6 pounds, including fuel, so
I want to avoid heavy pipe fittings.   I was thinking about trying small
copper sweat fittings next.  I've seen some pictures of flexible tubing
being used also.  There's an entire book written on RC balloon making, but
unfortunately it's all in German and even when using the online translators
I have a hard time reading it.  It's downloadable for free at the link
below. The pictures of the balloons people have made are amazing!

 

http://www.pinguballon.de/main/main_e.html

 

What surprised me in that book were the small size of the propane tanks they
are using.  Maybe RC balloons aren't designed to fly very long?  I have one
of those green camping propane cylinders connected to my burner and it
empties out pretty fast.  I'm planning on carrying two of those in the
blimp.   I think my first burner attempt had too much output though and
that's why it went through fuel so fast.  The flame looks like at least 8
feet tall.  I took the regulator off of one of those camping stove burners
that screw directly onto the tank and added it to my burner to tone it down,
which seems to work.  My blimp is 9 feet diameter and 30 feet long, so I
can't have a giant flame shooting straight up or it will burn right through
it.  I need more like a two foot flame angled at 45 degrees forward and
backward.

 

Another area I had problems with was the pilot light.  I couldn't find
anything small and light, so  I finally just used a standard brass propane
torch head for the pilot light, which works great but is pretty heavy.  The
burner setups in the book linked to above all look compact and light, but
it's hard to see what they are using for the pilot lights.

 

One reason for going to solenoid valves is I want to have one servo control
both burners.  That's pretty easy to do by letting the servo arm make
contact with micro-switches that will power the coils.  Battery technology
has really come a long way in the last 20 years, as has the miniaturization
of servos.  I have a 7.4v lithium polymer pack that can output 2.3 amp hours
of current and it only weighs 114 grams.  The 6 volt DC solenoid I was
looking at is rated for 6.3 watts, so that would be over two hours of
continuous open-time before the battery ran out.  Here's the data sheet:

 

http://www.passfire.com/misc/8256_NSFR1.pdf

 

 

The company selling those, valve-store.com, actually quoted me 9 weeks
delivery time!  Unfortunately I can't seem to find anyone else selling them.

 

-Kyle


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