news13.htm
Tri-Mode ARLA
Amateur Rocket Launch Assist (ARLA)
Newsletters and Random Thoughts
This page will include progress reports, notes, random brain farts,
and other ramblings.
September 24, 2004
Sputtering Restart or Last Gasp?
It's been over 2.5 years since I last wrote in this BLOG. I don't
think the term BLOG even existed back then. In the past I was always
the optimist thinking that I would soon get back to work on my ramjets.
When I moved and didn't have a decent shop I still worked on but
thought I would really get going once my shop was finished. Then I had
to wire it up and catch up on a few things. Then I took in my
grandaughter and had no time for myself. Then I thought I would get
that early retirement. Well, now I'm down to less than 10 months to
normal retirement and have mentally "made the turn onto final." Even
then, however, ramjets will have to share my time with many other things.
In the meantime, I wanted to get some notes out on things I've learned
even though I wasn't doing any productive testing.
Fuel Valves and Bladders
A few years ago I spent a lot of time trying to buy or design simple
fuel valves. Well, I've since found some very good sources. Some of
these are on/off and some are variable flow. A quick trip to town
should get you what you need.
- My favorite is boxed wine. These now come with different types of
valves, depending on the brand. And, as a bonus with your $7 valve, you
get 5 liters of liquid joy. And, as an added bonus, you get a fuel
bladder. Some of these bladders are Mylar and some are more like latex.
I've poured kerosene into the second type and left it for weeks with
no degradation. I think that Mylar would be impervious to almost every
type of fuel. What I haven't tried is to glue pieces of bladder into
special shapes.
- Speaking of Joy, laundry detergents now come in 2.5 gallon plastic
jugs, with valves, for about $10.
- 2.5 gallon jugs of drinking water also come with a variety of valve
types for about $2.
- Some of the personal sized water bottles have on/off valves so you
can squirt the water into your mouth or at your kids. The bottles can
also be used as fuel tanks, so long as you allow for air entry. By
placing a weight on the flange of the valve you can make it open
automatically on launch. Many dish soap bottles use the same type of
valves. And you can place washers under the caps to restrict the flow
rates.
- Some mustard bottles come with twist-on valves.
- Fish tank air valves, from the pet store, are very small, light
weight, and variable flow. You may have to buy 2-3 before you get one that
doesn't leak when shut off, but they do work.
- Water valves for travel trailers and motor homes are smaller than
those for houses and made of light-weight plastic. Home Depot even
carries these.
- For the purists, a quick trip to the lawnmower/small gas engine
shop will get you a real variable flow shutoff valve made for gasoline.
They're on the order of $4-6.
Igniters
This was another of those multi-year brain-racking exercises
in searching for what was right in front of me. I now know of
several sources of igniters for bench testing and for flight.
- If you want real hot bench start on your combustion chamber
testing get yourself a Taser for $40. Those things will kick out
a 2" spark that will knock your socks off. But, play nice with
them, they don't discriminate well between fuel and fingers.
- Another real hot igniter is a commercial neon sign transformer.
The first one I had when I was a kid was a used one given to me
for free. The one I have in my shop now (I make Jacob's Ladders
with it) I paid $70 for. This will kick start a 1.5 inch arc that
will expand to 4 inches. The current is much higher than the
Taser and it can literaly kill you in less than a heartbeat
(because you won't have any). But it will ignite your fuel.
- Stepping down a little in power, I currently use the guts
from a $30 bug zapper. I've run it on a wide-gap spark plug for
10 minutes at a time and, after many runs, it still works great.
- I've read about people using auto ignition parts and I'm
sure they work. Some even swear that the only way to go is a
Model A Spark Box. Hmmmmm!?
- For in-flight ignition there are hand-held, battery powered,
electronic barbecue lighters. They're very light weight and can
operate as long as your ramjet is flying.
- My new barbecue grill came with a nifty igniter that's
powerful enough to jump 3/8 inch gaps at four locations at once.
All off of a single AA battery. The sealed spark generator is quite
small and looks to be only a few ounces, though I haven't taken it
off.
- Of course, you can always use chemicals such as black powder,
flare chemicals, magnesium, model Estes rockets, and such. Model
Estes igniters can be used to start these chemicals, though they
take a second or two to work.
P.S.
By the way, that 500 gallon propane tank I bought is still
sitting where I parked it. My new neighbor has a 5000 gallon
water tank that would be great and I could probably get it cheap
but my other neighbor claims that it's his. There are some much
larger ones down the road that I could probably get for cheap but
I don't know how I'd get them home.
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This Page created September 24, 2004
Last Updated September 26, 2004