V-4 Missile Possibilities

On Sat, 17 Jan 2004 11:20:36 -0600, Alan Minyard
wrote:

Well, the V-1 used the same type of pulse jet, and they were routinely
shot down. The pulse jet was a dead end technology.

It *was* a dead-end technology. Certainly the arrival of the
gas-turbine meant that the noisy, ineffecient pulsejet was relegated
to the scrap-heap for many years.

However, Ray Lockwood, while working at the HIller Corp in the 1960's
did quite a bit of R&D on a valveless pulsejet that the company touted
as a highly efficient lift engine for VTOL applications.
Unfortunately the noise and vibration problems persisted and it was
never actually used in practice.

Since then however, pulsejets have been used by various manufacturers
for powering low-cost (often disposable) unmanned vehicles such as
RPVs, UAVs and target drones.

More recently, a relation of the pulsejet (the Pulse Detonation
Engine) has attracted a lot of research funding and its proponents
claim it will be *the* jet engine of the future -- offering very high
efficiencies, supersonic capabilities and high power to weight/volume
ratios.

Unfortunately, although a number of cumbersome prototypes have been
demonstrated and actually do run, the efficiency potential has yet to
be even remotely realized.

In the meantime, I have been working on a type of pulsejet engine that
is almost a half-way house in terms of efficiency and performance.
It's documented at http://aardvark.co.nz/pjet/xjet.shtml

No, it's never going to power a manned aircraft, and its efficiency
only matches that of a pure turbojet (but that's still 3 times better
than a regular pulsejet) -- yet it does have a very specific market in
which it represents an ideal powerplant. At a production cost of less
than 10% the price of the equivalent turbojet, it is ideal for
low-cost, high durabiity subsonic UAVs and RPVs.

So the pulsejet isn't dead -- it's just been relegated to a very
specific set of niches.
--
you can contact me via http://aardvark.co.nz/contact/

On 18 Jan 2004 22:34:52 -0800, (robert arndt) wrote:

3) the V-1 had to reach 250mph off the ramp for the pulsejet to
operate independently,

Sorry, take a look at the V1 launch videos (there are two) on this
page:

http://aardvark.co.nz/pjet/argusv1.shtml

and you'll see that the engine is running while the craft is static,
long before it reaches launch speed.

The Argus V1 engine produced a *STATIC* thrust of around 500lbs and a
maximum thrust of around 900lbs at 350mph or so.

There is probably no engine more misunderstood than the humble
pulsejet.

--
you can contact me via http://aardvark.co.nz/contact/

Bruce Simpson wrote in message . ..
On 18 Jan 2004 22:34:52 -0800, (robert arndt) wrote:

3) the V-1 had to reach 250mph off the ramp for the pulsejet to
operate independently,

Sorry, take a look at the V1 launch videos (there are two) on this
page:

http://aardvark.co.nz/pjet/argusv1.shtml

and you'll see that the engine is running while the craft is static,
long before it reaches launch speed.

The initial engine run was done remotely with the purpose of running up to operational temperature. Had the V-1 been launched cold the As014 engine would not function as the operating temperature inside the tube had not been reached. The V-1 could not propel itself off the ramp either and the cycle could not run independently until the missile hit 250 mph.

Rob

Bruce Simpson wrote in message . ..
On 18 Jan 2004 22:34:52 -0800, (robert arndt) wrote:

3) the V-1 had to reach 250mph off the ramp for the pulsejet to
operate independently,

Sorry, take a look at the V1 launch videos (there are two) on this
page:

http://aardvark.co.nz/pjet/argusv1.shtml

and you'll see that the engine is running while the craft is static,
long before it reaches launch speed.

The Argus V1 engine produced a *STATIC* thrust of around 500lbs and a
maximum thrust of around 900lbs at 350mph or so.

There is probably no engine more misunderstood than the humble
pulsejet.

As a follow-up I've read quite a few books on the V-1 launch sequence.
The photos or camera footage of V-1s running on the ramp do NOT mean
the pulsejet was functional.
The engine is being controlled remotely with compressed air and 75
octane fuel forced into the tube and ignited for exactly 7 seconds to
bring the tube up to operating temperature. This would be getting the
V-1 READY for launch. It took .5 seconds of accelleration at 16-17g to
get the missile up to 250mph and the As014 running independently.
If you look at all the other pulsejet aircraft projects they were all
intended to be:

a) launched from a ramp
b) take-off with aux. rockets/engines
c) be air-dropped/launched

Good examples are the Me-328 and Junkers EF 126 built in the USSR
postwar. The pulsejets could not function independently under 200 mph
just like the larger ramjets could not function below a certain speed.
That's exactly why the Germans considered them a "form" of ramjet with
intermittent combustion vs continous combustion. Hence also, the need
for some parts in the pulsejets vs LITTLE or no parts in the bigger
ramjets. There is a great misconception that all ramjets lack any
parts which is NOT true. From that view they consider a pulsejet
different from a ramjet... but they are both essentially just two
types of stovepipe engines.

Rob

p.s. I can see why most make that distinction but my posts were how
the Germans defined it since they were the ones who used them in
combat.

On 21 Jan 2004 08:53:05 -0800, (robert arndt) wrote:

As a follow-up I've read quite a few books on the V-1 launch sequence.
The photos or camera footage of V-1s running on the ramp do NOT mean
the pulsejet was functional.

Sorry but you're dead wrong.

The engine is being controlled remotely with compressed air and 75
octane fuel forced into the tube and ignited for exactly 7 seconds to
bring the tube up to operating temperature.

The engine was *started* using compressed air and, if you do a little
more research, you'll find that in colder weather they also used
acetylene because the gasoline was to hard to ignite at sub-zero
temperatures.

There's *no way* that the starting-air feeds to the Argus engine could
produce sufficient volume-flow to do anything other than start the
engine. If the Argus wasn't capable of running without forward
air-speed it simply would not run -- regardless of the relatively
small volume of compressed air used to start it.

As you can see in the videos on my website -- the engines were
definitely running in full pulsejet mode while stationary on the
launch ramps.

If, as you suggest, the engines required 250mph to operate, what kept
them going for the 5-seconds it took to go from rest to 250mph?

Just do some simple calculations on the amount of air that such an
engine consumes in 5 seconds and you'll see that, there's no way they
could carry that much compressed air onbard the craft. Indeed, the
air reservoirs could only hold a tiny fraction of that mount.

After WW2, the NACA tested a number of the Argus engines and ran them
statically (with no forced air) and at various simulated
ram-pressures. They determined that the engine produced 500lbs of
static thrust (with no forced air of any kind) and around 900lbs at
350mph.

This would be getting the
V-1 READY for launch. It took .5 seconds of accelleration at 16-17g to
get the missile up to 250mph and the As014 running independently.
If you look at all the other pulsejet aircraft projects they were all
intended to be:

a) launched from a ramp
b) take-off with aux. rockets/engines
c) be air-dropped/launched

This was necessary for the reasons I've outlined in a previous post --
ie: with a full fuel-load, the V1 was too heavy to take off without
either an extremely long runway (requiring extra guidance complexity
and a dolly or undercarriage) or by the use of the methods you
describe above. I had nothing to do with the engine requiring
forced-air to actually run.

Good examples are the Me-328 and Junkers EF 126 built in the USSR
postwar. The pulsejets could not function independently under 200 mph
just like the larger ramjets could not function below a certain speed.

While they may have been optimized for higher-speed operation (like
most of the German pulsejet designs), they could operate and produce
static thrust. The reason most of these were relegated to the role of
parsitic fighters is due to their incredibly limited duration, brought
about by the heavy fuel consumption of the pulsejet engines. By
launching them from larger piston-engined craft, they could be flowin
into the battle theater and then released. Their limited range would
have made it impractical for them to fly any distance on their own.

That's exactly why the Germans considered them a "form" of ramjet with
intermittent combustion vs continous combustion. Hence also, the need
for some parts in the pulsejets vs LITTLE or no parts in the bigger
ramjets. There is a great misconception that all ramjets lack any
parts which is NOT true. From that view they consider a pulsejet
different from a ramjet... but they are both essentially just two
types of stovepipe engines.

Just as a V12 Merlin and a turboprop are two types of propellor
engines -- so they must be the same right?

Sorry, but the physics and operating cycle of the pulsejet and ramjet
are as different as night and day. Indeed, a gas-turbine engine is
closer to a ramjet than a pulsejet is.

--
you can contact me via http://aardvark.co.nz/contact/

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



After WW2, the NACA tested a number of the Argus engines and ran them
statically (with no forced air) and at various simulated
ram-pressures. They determined that the engine produced 500lbs of
static thrust (with no forced air of any kind) and around 900lbs at
350mph.


Those tests are available at

http://naca.larc.nasa.gov/reports/19...a-wr-e-269.pdf

Keith

In article ,
Bruce Simpson writes:
On Sat, 17 Jan 2004 11:20:36 -0600, Alan Minyard
wrote:

Well, the V-1 used the same type of pulse jet, and they were routinely
shot down. The pulse jet was a dead end technology.

It *was* a dead-end technology. Certainly the arrival of the
gas-turbine meant that the noisy, ineffecient pulsejet was relegated
to the scrap-heap for many years.

Hello, Bruce, I've been wondering what you were up to.
Ypur'e the only fellow I know of with real pulsejet experience, so
perhaps you can give me a hand with something that's been puzzling me,
with reference to the Hiller Hornet. (The little pulsejet powered
helicopter. For those who don't know, it's a really simple way to
make a helicopter - Basically, it's a rotor, with a pilsejet on each
blade tip, and a handle to tilt the rotor disk (And thus its lift)
anywhere you want it to go. There's no torque reaction to cancel out,
or complicated & cranky transmissions.)

It seems like a real sweet setup, as long as you're hovering. But
once you start moving, you'll be ramming more air into engine on the
advancing blade, and much less on the retreating blade, since the
rotational velocity of the rotor, and that of the helicoper moving
through the air will add. It seems to me that if you can't keep some
level of fine control on the jet's thrust levels, you're going to have
an awful time maintaining a steady (and proper) rotor speed.
How throttleable is a pulsejet? Is it throttleable at all? If you can
throttle it, how fast does it respond?

--
Pete Stickney
A strong conviction that something must be done is the parent of many
bad measures. -- Daniel Webster

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

As a follow-up I've read quite a few books on the V-1 launch sequence.
The photos or camera footage of V-1s running on the ramp do NOT mean
the pulsejet was functional.

Sorry but you're dead wrong.

The engine is being controlled remotely with compressed air and 75
octane fuel forced into the tube and ignited for exactly 7 seconds to
bring the tube up to operating temperature.

The engine was *started* using compressed air and, if you do a little
more research, you'll find that in colder weather they also used
acetylene because the gasoline was to hard to ignite at sub-zero
temperatures.

There's *no way* that the starting-air feeds to the Argus engine could
produce sufficient volume-flow to do anything other than start the
engine. If the Argus wasn't capable of running without forward
air-speed it simply would not run -- regardless of the relatively
small volume of compressed air used to start it.

The pulsejet isn't running off a small volume of compressed air. The
distributor unit left of the ramp is feeding it and controlling the 7
second burn up to operating temperature.

As you can see in the videos on my website -- the engines were
definitely running in full pulsejet mode while stationary on the
launch ramps.

Remote controlled by the distributor unit.

If, as you suggest, the engines required 250mph to operate, what kept
them going for the 5-seconds it took to go from rest to 250mph?

That's a half-second or .5, not 5 seconds! Remember the 16-17g launch?



That's exactly why the Germans considered them a "form" of ramjet with
intermittent combustion vs continous combustion. Hence also, the need
for some parts in the pulsejets vs LITTLE or no parts in the bigger
ramjets. There is a great misconception that all ramjets lack any
parts which is NOT true. From that view they consider a pulsejet
different from a ramjet... but they are both essentially just two
types of stovepipe engines.

Just as a V12 Merlin and a turboprop are two types of propellor
engines -- so they must be the same right?

Sorry, but the physics and operating cycle of the pulsejet and ramjet
are as different as night and day.

We are talking As 014 here, an athodyd motor. One stovepipe vs another
except that to achieve pulse detonation some parts are needed in the
pulsejet. Boils down to simple intermittent combustion vs continous
combustion. Both a ramjet and pulsejet need close to 200 mph minimum
to operate independently. On a test rig you can FORCE feed air and
fuel to a pulsejet and even control ignition. But to use them in war
they had to be ramp-launched using a steam reaction piston or
air-dropped by parent aircraft.

Indeed, a gas-turbine engine is
closer to a ramjet than a pulsejet is.

Not in any way since neither a ramjet nor pulsejet have a compressor
or turbine.

Rob

On Wed, 21 Jan 2004 21:51:57 -0500, (Peter
Stickney) wrote:

It seems like a real sweet setup, as long as you're hovering. But
once you start moving, you'll be ramming more air into engine on the
advancing blade, and much less on the retreating blade, since the
rotational velocity of the rotor, and that of the helicoper moving
through the air will add. It seems to me that if you can't keep some
level of fine control on the jet's thrust levels, you're going to have
an awful time maintaining a steady (and proper) rotor speed.
How throttleable is a pulsejet? Is it throttleable at all? If you can
throttle it, how fast does it respond?

Depending on the design, pulsejets can be throttled over more than 50%
of their power range.

The problems you describe would not be an issue -- any more than the
effects of forward flight on a conventional helicopter where the
leading blade would tend to produce more lift (by virtue of its higher
airspeed) if its pitch were not reduced.

A sensible pulsejet powered helicopter (that's an oxymoron :-) would
have the air intakes placed close to the root of the rotor blade so
that the variation in ram pressure due to the combination or rotation
and forward speed would be reduced.

In reality, this extra lift produced by the leading blade would
manifest itself, not as a roll, but as a pitching motion due to the
effects of gyroscopic progression.

--
you can contact me via http://aardvark.co.nz/contact/

On 22 Jan 2004 08:46:18 -0800, (robert arndt) wrote:

There's *no way* that the starting-air feeds to the Argus engine could
produce sufficient volume-flow to do anything other than start the
engine. If the Argus wasn't capable of running without forward
air-speed it simply would not run -- regardless of the relatively
small volume of compressed air used to start it.

The pulsejet isn't running off a small volume of compressed air. The
distributor unit left of the ramp is feeding it and controlling the 7
second burn up to operating temperature.

Based on some quick mental calculations the Argus requires something
like 1,500 cubic feet of air per minute when running. I'll leave you
to do the calculations but rest assured that there is *no* connection
to the Argus engine capable of supporting anything like that flow-rate
-- and I have a full set of plans here.

Sorry, but the physics and operating cycle of the pulsejet and ramjet
are as different as night and day.

We are talking As 014 here, an athodyd motor. One stovepipe vs another
except that to achieve pulse detonation some parts are needed in the
pulsejet.

Sorry but there is *no* detonation in a pulsejet engine. Go do some
research on the difference between deflagration and detonation.

Boils down to simple intermittent combustion vs continous
combustion. Both a ramjet and pulsejet need close to 200 mph minimum
to operate independently.

Go back and visit my website -- you'll see several videos of pulsejets
operating statically with absolutely *no* forced air. You'll even see
the video of my large pulsejet engine that starts simply by turning on
the gas and the spark with not a zephyr of forced air anywhere in the
vicinity.

Indeed, a gas-turbine engine is
closer to a ramjet than a pulsejet is.

Not in any way since neither a ramjet nor pulsejet have a compressor
or turbine.

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.

Note also that both the gast turbine and ramjet perform constant
pressure combustion whereas the pulsejet approximates constant volume
combustion.

There are indeed more similarities between a ramjet and a gas-turbine
than there are between a ramjet and a pulsejet -- but don't take my
word for it -- go do some reading.


--
you can contact me via http://aardvark.co.nz/contact/