Light weight Euro-diesels

"Tim Ward" wrote in message
ink.net...

"Bill Daniels" wrote in message
...

"Morgans" wrote in message
...

"Bill Daniels" wrote in message
...
Hey, you're gonna have to heat the diesel fuel to keep it from
gelling
so
why not use the fuel as a coolant. If the tanks are of the wet wing
type,
you're almost home free. (I actually had a guy ask me how that
would
cool
the engine if I ran out of fuel.)

The real question is, how will the engine cool, once you have the fuel
to
the boiling point, and also how rapidly can you boil off a tank of
fuel.
--
Jim in NC


Why would the fuel boil? Glycol/water coolant doesn't boil if the
engine
temps are normal. I seem to recall the boiling point of diesel is
greater
than glycol/water. That would depend on the rate the heat was rejected
by
the 'radiator' and the pressure of the cooling system. If heat input
was
less than the heat rejection capacity of the radiator, then the fuel
"coolant" wouldn't overheat.

Using fuel as a coolant is a respected technique used by rocket engines
and
the SR-71.

Bill Daniels


It doesn't boil because it's under pressure. You wanna pressurize your
Nimbus wings to, say, 32 feet of water pressure?

Tim Ward



Who said anything about carbon composite wings? If anyone tried this
scheme, they would use thick metal wing skins with enough stringers to
withstand a little overpressure.

Anyway, the 75 gallon tanks in my Nimbus wings will be used for Jet A when I
put the little retractable turbojet on it.

Bill Daniels

"Bill Daniels" wrote

Why would the fuel boil? Glycol/water coolant doesn't boil if the engine
temps are normal.

How are the temps going to stay normal, once the fuel has gotten up to
engine operating temperature? Remember the premise that the skins will not
get rid of the heat fast enough? Someone has proven it here before. The
fuel will then get hotter and hotter, until it is boiling. The change of
state may then keep the engine from melting down, at least until all of the
fuel is gone.

Using fuel as a coolant is a respected technique used by rocket engines
and
the SR-71.

Rocket engines only use the fuel one time for cooling, and that is on the
way into the combustion chamber. If it had to recirculate to keep the
engine cool, the fuel would over pressure and over temp in a short period of
time.

The SR-71 does not use the fuel to cool the engine, but uses the fuel to
cool the hot parts of the airframe, or in other words, redistribute the hot
skin temps. It should also be noted that the fuel was very special, and
only available at a few sites around the world. Are you planning on cooling
your skins, and where are you going to get SR-71 fuel?

Sorry, but your examples are not valid. If it worked, racers would do it,
and so would some others. It does not work. those are my final words on
the subject. See ya. -)
--
Jim in NC

wrote


No need to apologise. I would first have to take you seriously in order
to be disappointed. This is usenet afterall, and a forum about
_experimental_ aircraft. I would think enthusiasm towards innovation
would be met with a slightly more positive attitude.

Right but experiments are take on,, when models and calculations show that
the proposed idea might work. It has been shown via well respected
concepts, that the numbers will not let it work. Sure, try it if you want,
but I would not want to waste my time and mones=y on something that falls
way short by the numbers.

Can I buy an "A"?

Sure! ;-)
--
Jim in NC

"Morgans" wrote in message
...

"Bill Daniels" wrote

Why would the fuel boil? Glycol/water coolant doesn't boil if the
engine
temps are normal.

How are the temps going to stay normal, once the fuel has gotten up to
engine operating temperature? Remember the premise that the skins will
not
get rid of the heat fast enough? Someone has proven it here before. The
fuel will then get hotter and hotter, until it is boiling. The change of
state may then keep the engine from melting down, at least until all of
the
fuel is gone.

You know, I just don't buy the "skin radiators won't work" theory. The
pre-war Schneider Cup Seaplane racers did use skin radiators to cool some
really big engines. There are LOTS of reasons skin radiators weren't used
on WWII fighters - bullet holes being one. Since then, piston aero engines
have been air-cooled.

About 10 years ago I did a crude experiment. The fuel tanks on a PA-28 are
wet leading edge cells with only the wing skin between the fuel and the
airstream. I filled the tanks on my Archer II from a fuel truck that had
been sitting in the summer sun all day, measured the fuel temperature in the
right tank and went flying in the cool evening air using the fuel in the
left tank. 15 minutes later, after landing, I measured the right tank fuel
temperature again. It was a LOT cooler than when I started. This is an
experiment that anybody can do.

Using the tank wetted area, the before and after fuel temperature, the OAT
and the specific heat of AVGAS, I calculated the heat rejection of the tank
as if it were used as a radiator. There was huge heat flow from the fuel in
the tank to the airstream. It looked as if it would be larger than the
heat rejection of the O-360 in the Archer's nose if the fuel temperature
were as high as coolant would be.

Now maybe if the fuel were at 200 F, the heating of the boundary layer would
trip it to turbulent flow and create a lot of drag but I doubt that an
Archer has much laminar flow anyway. If the fuel tank/radiator were in the
propeller slipstream where it belongs there wouldn't be any laminar flow to
trip.

Bill Daniels

Montblack wrote:

("Morgans" wrote)

Your statement may or may not be true, but I'm certainly not going to go
around wringing my hands over a 4 banger.



There is precedent.

http://www.edmunds.com/insideline/do...rticleId=68272
Honda Civic history

Oh, heck, the Untied States has a history of resting on its laurels
while foreign competitors eclipse its technology.

Just look at Airbus.

As far as engine systems go, Ford and GM could have had a 6 year head
start on hybrids, but they determined that hybrids "were not
economically feasable". The result? Now Honda and Toyota have a firm
lead in hybrid technology and Ford and GM are playing catch up.

And this is something that has happened over and over and over again.

If you aren't wringing your hands over this 4 banger then you should be.
Four bangers grow up.


AP

Morgans wrote:

Diesel is still cheaper than jet fuel. Or isn't it? I've been too
afraid to go to the pump the past few days

One thing I have to ask, is if that engine is rated to use Jet A? From what
I have read, many are not, because some injector pumps need the lubrication
that diesel provides, that Jet A does not have. If the pump is not able to
handle the Jet A, it will quit in fairly short order.

Not if you mix in 2% biodiesel. That replaces the lubrosity lost by
eliminating the sulfides in the diesel fuel.


AP

Philippe Vessaire wrote:

No anti-froze agent needed, just an fuel/water heat exchange and the whole
tank become warmer when the engine is runnig. For pure biodiesel, the car
choice is an exhaust/fuel heat exchange.

I've never seen this. All of the biodiesel/vegoil cars I've seen have
used coolant/fuel heat exchangers.


AP

Philippe Vessaire wrote:

For biodiesel cars, some people juste run a copper tube near exhaut and the
same job is done. These cars still need a pure diesel start and stop.

Biodiesel does _not_ require a petrodiesel start/stop fuel. You're
thinking of straight vegetable oil systems.

The only thing you need to do to convert a diesel vehicle to biodiesel
is pour it into the tank.


AP

Morgans wrote:

wrote


The other possibility would be to stick a radiator in each wing root
and funnel ram air through the radiator into the wing cavity. The
warmed air would then be the heating element. I wonder if that would be
sufficient to prevent gelling and also provide some minor wing heat
without all the complexity.


You really need to take some physics and thermodynamics. Right now, you
need to buy a vowel.

I'm only kinda kidding. What you are proposing isn't being done, because it
won't work. Sorry.

Well, again, has anyone done the engineering on this?

As I understand it, what he's talking about is simply using underwing
radiators and ducting the exhaust air from the radiators through the
interior of the wings before allowing it to flow out of exhaust ports.
I can see how it might work, the question is how well it would work.
Would it provide enough heat to the wing skin to keep ice from adhering
to it?


AP

Alan Petrillo wrote:


No anti-froze agent needed, just an fuel/water heat exchange and the
whole tank become warmer when the engine is runnig. For pure biodiesel,
the car choice is an exhaust/fuel heat exchange.

I've never seen this. All of the biodiesel/vegoil cars I've seen have
used coolant/fuel heat exchangers.

Just a copper tube along the exhaust tube do the job in homebuilt
conversion.
Other people do two rounds on the exhaust tube.


By
--
Pub: http://www.slowfood.fr/france
Philippe Vessaire Ò¿Ó¬