Here are some thoughts on using Propane in a Europa:
**Remember you need to use liquid propane going to the motor. Somehow you need
to have a way of heating the liquid propane where it has a phase change to vapor
and is trying to get to approx -42F
**In the USA it is hard to find 100% Propane all the time. The boiling point of
propane is lower than the boiling point of Butane, thus for a given temperature
Butane has a higher vapor pressure. In the winter, (and sometimes in the summer
if it is old fill up) you buy a mixture of Propane and Butane. Butane has
less BTUs per gallon than Propane. OK so you now want to know just how much
power
loss there is going to be (and decreased range) compared to 100% Propane
with the fuel you are using. You need to keep the vapor pressure high enough to
allow full power and low enough to prevent the tank blow off valve from venting.
You can warm tanks in the winter with electric heater, or you can inject
Nitrogen. The problem with Nitrogen (or Argon or other inert gasses, I think
perhaps
CO2 will work) is if you don't use all the fuel up, if it gets hot out,
the valve may vent.
**In aluminium and Stainless tanks you need to over size them by ~ 25% to allow
for the expansion of the liquid fuel. Thus you need a physical tank size of 25
gallons to carry 20 gallons
**I am a Hot Air Balloonist and build my own burners and tanks. For some time 10
gallon aluminium tanks (capacity is 12.5 gallons) were very common. There were
some 15 gallon tanks but boy were they expensive. I used to garbage pick
forkllift
tanks which hold ~ 7.5 gallons (capacity ~ 10 gallons) and cut the bottom
off one and the top off the other and weld them back together. One problem
with many tanks were that they used too thin a wall in the dip tube and they
would crack and fail. I would just extend the dip tube and make it more robust.
Voila! 15 gallon tank for cheap. Anyway tankage kills you. With a 10 gallon
Worthington cylinder it weighs over 30 pounds! Anyway keep in mind the tanks
have
to be over sized to allow for expansion.
**WATER IN FUEL IS BAD! When you change phase from liquid to vapor, things get
cold. The best scenario is the restriction is at the heat exchanger and is warm.
That said if you have any restriction before, it will get below freezing in
a hurry. If there is moisture in the fuel it will freeze. Best way is to inject
under high pressure some Methanol to be sure. PITA. Of course you could drain
tank, open it and pour in. You also want to be able to get inside tank and
clean it out from time to time. You can't believe the debris that collects.
**I have refueled many hundreds of gallons by simple transfer method. All you
need
to do is connect a full tank to an empty tank, liquid to liquid line and open
the vent on the empty tank. In 5 or 10 minutes 10 gallons is transfered. You
can speed the process by raising the full tank above the empty tank and heating
the full tank or pressurizing it with some inert gas. So if you were to garbage
pick some old fork lift tanks, they are a nice size to carry the stuff
around with. BTW if you garbage pick several forklift tanks and gang them
together
in parallel, they make a nice compressor tank! If you garbage pick a
refrigerator
(or two or three) compressor/s they work well for pumping up the tanks.
Yes there is the hassle of transporting a lot of propane in your vehicle and
the fact dumping propane into the atmosphere does not do the the ozone layer
any good.
**Did you ever see Cozy or Long Easy baggage pods? Anyway seems like an ideal
thing
to wind your own propane tanks in a nice aerodynamic shape. I would bet that
you the wing could support more if some of the weight is not at the root?
Anyway here's a pic:
http://www.europaowners.org/forums/gallery2.php?g2_itemId=82116
**I was planning a long distance flight for a while back and decided to use
Kerosene
as the fuel of choice. Tankage can be unbelievable light. Just hang 1 gallon
plastic milk containers from the balloon and discard them when used up. Idea
was to pour into one of my 15 gallon garbage picked tanks and pressurize with
either propane and use a burner similar to a current hot air balloon burner,
or use the monstrosity I made which was a leaf blower connected with a flex
shaft to a home oil burner pump. It went to preheating coils and jets. Worked
great except it had a motor running that would be annoying after a while. The
other problem is burned Kerosene kills balloon fabric, so that needs to be in
the equation.
Anyway even if you discard lightweight tanks after they are spent, compared to
kerosene or gasoline net is less BTUs for more weight. That said it is far far
far better than if you compared to the very best electric system out there.
Why doesn't someone lend their unfinished project to Mythbusters along with this
post??
I say it is plausible!
I guess you could use an oil heat exchanger, but water may be easier.
Might be nice to add 16 to 18" extra span to each wing where you attach the pods
with a full length CF spar? If you want to make a new wing with internal tanks,
be sure to allow for easy cleaning and inspection.
Can you say BLEVI?
(Boiling Liquid Expanding Vapor Explosion)
http://www.youtube.com/watch?v=ZnsAV1ph2CU
Ron Parigoris
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=337612#337612
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