V-4 Missile Possibilities

(robert arndt) wrote in message . com...
Bruce Simpson wrote in message . ..
On 21 Jan 2004 08:53:05 -0800, (robert arndt) wrote:


I think you'll find that Paul Schmidt's valveless pulsejets (that were
superior to the valved Argus engies which he nevertheless assisted
Argus in designing) could resonate at zero velocity. I do recall
reading that a V1 engine required 26mph to opperate but I'm all open
on this. I imagine that the expulsion of hot gases out of the rear of
the Argus tube could by its own inertia continue moving and thereby
partialy void the combustion chambers and create sufficient vacuum to
draw in a fresh charge of air over the valves. Similar to the way
'extractor' exhausts work in cars. (I think the term is
Schwungaufladdung in German IC engine terminology)

Some of Schmidt's cruise missiles designes and engines had zero
frontal area for the intake. The intake was simply a 'cigar band'
mesh 2/3rds of the way along the missile. The resonating effect
drawing in air around the circumfrence. Very elegant.

Schmidts designes were more advanced, superior anbd actualy worked at
700kg thrust but I beleive they didn't get into the V1 because Schmidt
wanted to hang onto his patents which helped Argus advance faster into
production.

Bruce Simpson incidently has quite a lot of credibillity on these
matters as he was featured in Junkyard wars making pulsejet powered go
carts and featured in the news for his dersire to build a backyard
cruise missile.

Bruce Simpson wrote in message . ..
On 22 Jan 2004 08:46:18 -0800, (robert arndt) wrote:



SNIP

Incorrect -- a gas-turbine is a constant combustion device,like a
ramjet and whereas a turbine has a rotating compressor, the ramjet
achieves an increase in static pressure by using a diffuser (go read
up on Bernoulli's theorum to see how that works.


During the 1920s and 1930s a German engineer called Holzworth deigned
and built for the German railways several "constant volume combustion"
gas turbines.

Also von Ohain while working at Heinkel also inspired the construction
of a 60kg thrust constant volume combustion jet engine that produced
60kg thrust. It was damaged in testing and not pursued because of the
urgency of other war time work.

Holzworths gas turbine consisted of a large water jacketed chamber
that was filled with compressed air via a large hydraulically
opperated poppet valve. The Hydraulic poppet valve was then closed,
the mixture ignited and then a second hydraulicaly opperated poppet
valve was opened to exhaust the mixture over a large water cooled
power turbine.

The whole thing opperated at about 50 cycles a second. A pair of
chambers and tubines coupled to a common shaft was used to provide
smooth power. The advantage being that the device was much less
sensitive to turbine and compressor efficiency, the combustion was at
a higher temperature becuase the intermittant nature allowed cooling.

Holzworths engines worked quite well on gas, liquid fuels. They
worked quite well on powdered coal though the abrasion on the turbines
was fairly high.

At one point it seemed that constant volume combustion would win out
over constant pressure combustion. Several projects were looked at by
the Germans as they seemed superior at both generating thrust and gas.
Some used conventional compresseors and systems of poppet valves and
spark plugs that needed to be elaborately sequenced. (this
comblicated things)

Von Ohain engine relied upon a sort of rotating combustion chamber
consisting of blades which partitioned the chamber into sections.
von Ohains engine does have a name (after the town it was built in)
can't recall right now.

All covered in Anthony Kay's book "German Jet Engine and Gas Turbine
development 1930 to 1945"


A lot of these things are worth looking at again.

On 22 Jan 2004 20:46:44 -0800, (Eunometic)
wrote:

At one point it seemed that constant volume combustion would win out
over constant pressure combustion. Several projects were looked at by
the Germans as they seemed superior at both generating thrust and gas.
Some used conventional compresseors and systems of poppet valves and
spark plugs that needed to be elaborately sequenced. (this
comblicated things)

Work is still being done on the application of pulsed combustion to
gas-turbine engines -- but there are many problems that have not yet
been overcome.

In theory, a pulsed combustor can be more efficient than a
steady-state combustor.

--
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