Discussion:
A simple surface-to-air missile
(too old to reply)
c***@googlemail.com
2006-12-30 07:37:59 UTC
Permalink
I've recently been thinking about a simple design for a surface-to-air
missile, of the sort that Germany could presumably have produced during
WW2. When I say simple I'm primarily refering to the guidance method,
since that is the hardest part of the missile to produce (unguided
rockets were used in the Napoleonic wars and probably earlier).

I'm aware that Nazi Germany had a number of SAM programmes, but I've
not read anything that suggests they tried the guidance method I have
in mind. Anyway, here it is:

The weapon system consists of the missile and a ground-based radio
transmitter that illuminates the target aircraft. The missile nose
contains 4 sensors that detect radio waves of the frequency of the
transmitter. One pair of sensors are placed so they differentially
detect radiation from the left or right side of the missile; these move
control fins to keep the missile pointing in a direction so that both
sensors detect the same amount of radiation (which will be when the the
missile is pointing directly at the target).

The other pair of sensors does the same thing, but are placed to
differentially detect radiation coming from above and below the
missile.

the control fins could work by acting aerodynamically on the airflow
around the moving missile; they could also
probably direct the direction of the exhaust of the rocket (a method
used in the V-2).

It is thus a SARH (semi-active radar homing) missile, where both the
missile and the ground installation can be made quite simple. The
ground installation is a radio transmitter able to trasnsmit an
unmodulated signal of a given wavelength (it would probably be best if
the signal is somewhat directional, which would give the system longer
ranger but require an operator to point it roughly at where the target
aircraft is). The four sensors in the missile need to be able to detect
radiation differently depending on where it is coming from; I presume
this could be done be shielding each of them in a ferrous box, with the
opening pointing at a different part of the sky for each sensor. (Note
that an American homing torpedo successfully used this guidance method
during WW2).

So I was wondering:

1. would a setup like this work, or am I missing something?

2. was the design I've described feasible with 1940's technology?

3. given that Nazi Germany had a large number of missile programmes,
why did they not try something like this? (Or perhaps they did and I'm
unaware of it)

4. would a modernised version of the same design be feasible today? (I
expect you could make the missile more sophisticated and resistant to
jamming by making it microprocessor controlled)

5. have any SAMs like this ever been produced?
Henry J Cobb
2006-12-30 10:07:54 UTC
Permalink
Post by c***@googlemail.com
I'm aware that Nazi Germany had a number of SAM programmes, but I've
not read anything that suggests they tried the guidance method I have
The weapon system consists of the missile and a ground-based radio
transmitter that illuminates the target aircraft. The missile nose
contains 4 sensors that detect radio waves of the frequency of the
transmitter. One pair of sensors are placed so they differentially
detect radiation from the left or right side of the missile; these move
control fins to keep the missile pointing in a direction so that both
sensors detect the same amount of radiation (which will be when the the
missile is pointing directly at the target).
The Allies had much better radar tech so could have trivally jammed such
a missile.

-HJC
c***@googlemail.com
2006-12-30 11:44:57 UTC
Permalink
Post by Henry J Cobb
The Allies had much better radar tech so could have trivally jammed such
a missile.
I'm sure they would have used ECM against it, but I doubt that jamming
would have been completely effective. It's relatively easy to jam a
weapon such as the Fritz-X, in which a radio signal sent control
messages to the missile; simply put out a more powerful signal on the
same frequency to drown outr the control signal.

But with the proposed system this won't work, because the missile would
home in on the jamming signal.

There are other measures the Allies could take:

1. release chaff to create multiple returns for the missiles to home in
on. This would work, however they would have to continually release
chaff all the way to Germany and back, which would take up weight that
could otherwise be used for bombs. Alternately, they could only release
the chaff when they detected radio illumination, however this would
rely on the chaff being spread widely about from the aircraft by the
time the missile is close, and there might not be anough time to do
that.

2. have a jamming radio transmitter trailing behind the aircraft (like
Typhoon's towed decoy as part of DASS). However, the first missile hit
will take out the decoy, then the second will hit the aircraft. Also,
the decoy would take up weight and cause drag, thereby reducing bomb
load carried.

3. droppable radio transmitters that broadcast on the same frequency
that the Germans are using. However, the Germans could switch between a
range of frequencies; and as with the other measures, it takes up
weight that could otherwise be used for bomb load.

4. an anti-radiation missile that homes in on the Germasn radio
transmitters. However, if they are only switched on for a short time,
with might be difficult to achieve.

So while I am sure the Allies would have used countermeasures, once
they realised what threat they were facing, it is not obvious to me
that the countermeasures would be 100% successful -- it seems more
likely that they would be partially successful but that the German
missiles would still have some effectiveness.
IsaacKuo
2006-12-30 16:13:36 UTC
Permalink
[...snipped some countermeasures...]
Post by c***@googlemail.com
So while I am sure the Allies would have used countermeasures, once
they realised what threat they were facing, it is not obvious to me
that the countermeasures would be 100% successful -- it seems more
likely that they would be partially successful but that the German
missiles would still have some effectiveness.
There's one countermeasure which would have worked...the
Allies could simply build more planes than the Nazis built
SAMs. It worked with the Sherman tanks...

In any case, I'm not sure that with 1940's technology, a
SAM is a better investment than manned rocket
interceptors like the Me163 or Natter. The big problem
with the Me163 was that its volatile fuel made it a pilot
killer on landing. Perhaps the development of hybrid
rocket technology or some sort of parachute based
landing system could have made for an effective weapon
system.

Either would surely have reduced the top speed, but it
could have still been blazing fast compared to the
propeller driven enemies. Besides, the excessive speed
made it difficult to shoot down the targets as it was.

Isaac Kuo
c***@googlemail.com
2006-12-30 20:55:07 UTC
Permalink
Post by IsaacKuo
[...snipped some countermeasures...]
Post by c***@googlemail.com
So while I am sure the Allies would have used countermeasures, once
they realised what threat they were facing, it is not obvious to me
that the countermeasures would be 100% successful -- it seems more
likely that they would be partially successful but that the German
missiles would still have some effectiveness.
There's one countermeasure which would have worked...the
Allies could simply build more planes than the Nazis built
SAMs. It worked with the Sherman tanks...
Well, yes, since the Allies had more industrial capacity than the
Germans. But it seems a rather inelegant solution to me. And SAMs might
still be more effective for Germany than heavy AA guns, which were
expensive and brought down relatively few aircraft (anyone got any
stats on how many AA shells it took to down one bomber?)
Post by IsaacKuo
In any case, I'm not sure that with 1940's technology, a
SAM is a better investment than manned rocket
interceptors like the Me163 or Natter. The big problem
with the Me163 was that its volatile fuel made it a pilot
killer on landing. Perhaps the development of hybrid
rocket technology or some sort of parachute based
landing system could have made for an effective weapon
system.
The Natter was an interesting concept that possibly could have been
made to work with longer development time.
Post by IsaacKuo
Either would surely have reduced the top speed, but it
could have still been blazing fast compared to the
propeller driven enemies. Besides, the excessive speed
made it difficult to shoot down the targets as it was.
As long as the speed was greater than that of the escorting fighters,
it would be enough, agreed.
Eunometic
2006-12-31 00:39:18 UTC
Permalink
Post by c***@googlemail.com
Post by Henry J Cobb
The Allies had much better radar tech so could have trivally jammed such
a missile.
I'm sure they would have used ECM against it, but I doubt that jamming
would have been completely effective. It's relatively easy to jam a
weapon such as the Fritz-X, in which a radio signal sent control
messages to the missile; simply put out a more powerful signal on the
same frequency to drown outr the control signal.
Fritz-X wasn't that easy to Jam and the jamming system that may have
worked relied upon investigation of captured of missiles. Hs 293 even
harder because, some usenet sources claim, it had more frequencies.
Certainly Kehl-Strasbourg command link had variations and there were
alternatives under development.

A SAM system kept only on German soil and not shipped to coastal France
(Bruneval raid) or Nth Africa or shipped to Italy like Frtiz-Xand
thereby vulnerable to captured is going to be very hard to compromise
in a timely fashion.

Secrecy is one of the keys, having another system or modification in
place for when it finally is compromised is the other. Relying purely
on building in jam resistence is likely to fail at some point. In this
area the allies tended to be philosophically ahead of the Germans.
Post by c***@googlemail.com
But with the proposed system this won't work, because the missile would
home in on the jamming signal.
Home on jam is incorporated into modern missiles, eg AMRAAM. Due to
the difficult of jamming modern missiles disposable and towed decoys
are appearing.

I would sugggest that the home on jam would be best kept in the
illuminating radar to help it keep a lock rather than the missile due
to the complexity of such systems. Apart from noise jamming and
barrage jamming, there would be attempts to spoof with false delayed
echoes etc.

The allies incidently had a countermeasure to 'home on jam' in the
carpet II jammers, They had dozens of aircraft alternatly switching on
and off and frequency band shifting since they feared that German nigh
fighters would home in on the jamming siganls. Indeed to the Germans
did try install eqipment on the ground at least and try and home onto
jammers and probably succeded on some occaisions.
Post by c***@googlemail.com
1. release chaff to create multiple returns for the missiles to home in
on. This would work, however they would have to continually release
chaff all the way to Germany and back, which would take up weight that
could otherwise be used for bombs. Alternately, they could only release
the chaff when they detected radio illumination, however this would
rely on the chaff being spread widely about from the aircraft by the
time the missile is close, and there might not be anough time to do
that.
Progressively more advanced German countermeasures overcame
chaff/window for ground based radars. See my other post. It was more
of a problem for airborn radars at the time which required complicated
circuity to compensate for the relative motion. At best chaff would
reduce range and create an artificaly large target, a 'tail' that
disapperared as it slowed and that might seduce a missile to lock onto
an area behined the tail of the aircraft. Even if unsucesfull In
combination with noise and seduction jamming the accuracy of the
missile might be reduced sufficiently.
Post by c***@googlemail.com
2. have a jamming radio transmitter trailing behind the aircraft (like
Typhoon's towed decoy as part of DASS). However, the first missile hit
will take out the decoy, then the second will hit the aircraft. Also,
the decoy would take up weight and cause drag, thereby reducing bomb
load carried.
Wasserfall had a massive and powerfull warhead designed to take out a
whole formation so that decoy better be on a long line.

Many of these mssiles had suprisingly large warheads something which
was probably made possible by their large size and the slowness of the
target.

A towed decoy is an option but it is going to be a 'hairy' one.
Manual intervention is likely to be possible at some points to prevent
the seduction given the slowness of the intercept.
Post by c***@googlemail.com
3. droppable radio transmitters that broadcast on the same frequency
that the Germans are using. However, the Germans could switch between a
range of frequencies; and as with the other measures, it takes up
weight that could otherwise be used for bomb load.
The British did have a false echoe system that created false echoes by
using a liquid filled sonic echoe chamber to create a delayed pulse.
Ofcourse by adding various forms of encoding, frequcny changing,
chirping of the signal this could be overcome. I'm not sure how the
Germans overcame this though they did use accoustic delay lines in
their equipment.
Post by c***@googlemail.com
4. an anti-radiation missile that homes in on the Germasn radio
transmitters. However, if they are only switched on for a short time,
with might be difficult to achieve.
Indeed, the Wassefall missile had a similar gudience system to the V2
which incorporated an accelermoter. The difference being that
Wasserfall incorporated a full 3-axis system similar to that only
tested for advanced forms of the V2 to allow for the more complicarted
flight path. The missile would have flown under unjamable inertial
guidence in the initial phases of flight. This won't prevent jamming
but it will reduce warning and response time.

At Mach 3 the Wassefall would win out over the US anti radar missiles
which were at that time all based glide bombs or vertical gravity
bombs. The US did start a guided missile development program but (Hap
Arnold) they started several years latter. Incidently the Germans also
had a radar homming seeker called "Radischien" (raddish) that was
tested succesfully against a dummy radar on the Haggelkorn (Hailstsone)
glided bomb and was intended for Fritz-X. It was intended to attack
allied radars and LORAN navigation stations. I believe the test
missile hit the target within 5 meters.
Post by c***@googlemail.com
So while I am sure the Allies would have used countermeasures, once
they realised what threat they were facing, it is not obvious to me
that the countermeasures would be 100% successful -- it seems more
likely that they would be partially successful but that the German
missiles would still have some effectiveness.
The secret is keeping your system secret and having another ready to
take its place when it is compromised, All of the major German airborn
and ground based radars were compromised by capture or espionage.

What is needed is a rather massive investment in ECCM and ECM to keep
ahead of the other guy who you assume is going to be smart enough to
respond. In the German situation they had two problems one is that
they had less resources than the allies, secondly they had no safe
haven like the allies had in the US, thirdly they had made a mistake in
shutting down much of their microwave radar development in 1940 along
with other weapons programs because it would be 2 years to field a
weapon system. They had at that time an 8kW 50cm magnetron radar that
had a respectable detection range similar to the conventional 54cm
Wurzburg. They had an 8kW 18-22cm magnetron in a lab that needed an
radar built around it. At this point the whole development is delayed
due to a philosophical approach that requires the development of
tunable versions since the issue of jamming is comming up. It is
interesting to note that one of the developers of British Microwave
radar, Sir Bernard Lovell, makes the the point that during the Battle
of Britian microwave radar development was officialy disbanded and
cancelled to concentrate efforts on existing systems. The 'order' was
ignored by British technocrats by various means.

There are indeed plausible situation where they Germans could have
fielded a SAM missile in a timely fashion. Taking resources of the V2
was one such way. In General the several SAM missile developments
didn't receive sufficient priority till it was too late. The E4 Enzian
missile was actually 'provisionallly qualified for mass production'
according to Igor Witkowski writing in "Truth about the Wunderwaffe".
He also notes that the situation of the Reich in late 1944 made this
unrealistic.
c***@googlemail.com
2006-12-31 20:07:19 UTC
Permalink
Post by Eunometic
Post by c***@googlemail.com
Post by Henry J Cobb
The Allies had much better radar tech so could have trivally jammed such
a missile.
I'm sure they would have used ECM against it, but I doubt that jamming
would have been completely effective. It's relatively easy to jam a
weapon such as the Fritz-X, in which a radio signal sent control
messages to the missile; simply put out a more powerful signal on the
same frequency to drown outr the control signal.Fritz-X wasn't that easy to Jam and the jamming system that may have
worked relied upon investigation of captured of missiles. Hs 293 even
harder because, some usenet sources claim, it had more frequencies.
Certainly Kehl-Strasbourg command link had variations and there were
alternatives under development.
A SAM system kept only on German soil and not shipped to coastal France
(Bruneval raid) or Nth Africa or shipped to Italy like Frtiz-Xand
thereby vulnerable to captured is going to be very hard to compromise
in a timely fashion.
Yes. Although they may well have deployed it to France after D-Day.
Post by Eunometic
Secrecy is one of the keys, having another system or modification in
place for when it finally is compromised is the other. Relying purely
on building in jam resistence is likely to fail at some point. In this
area the allies tended to be philosophically ahead of the Germans.
At this stage in the war, didn't both sides automatically assume that
everything they did would be subject to counter measures, and plan for
counter-counter-measures accordingly?
Post by Eunometic
Post by c***@googlemail.com
But with the proposed system this won't work, because the missile would
home in on the jamming signal.
Home on jam is incorporated into modern missiles, eg AMRAAM. Due to
the difficult of jamming modern missiles disposable and towed decoys
are appearing.
Yes. bear in mind that modern missiles have microprocessors built in so
there is a wider range of behaviour they can do. A simple control
system for a WW2 missile, particularly if the unit cost is kept down,
isn't going to be able to do anything as sophisticated.
Post by Eunometic
I would sugggest that the home on jam would be best kept in the
illuminating radar to help it keep a lock rather than the missile due
to the complexity of such systems. Apart from noise jamming and
barrage jamming, there would be attempts to spoof with false delayed
echoes etc.
If the missile is only detecting the direction of the target, and not
the range, why bother to counteract the jamming? One reason might be if
the missile was also using the strength of the signal as a proximity
fuze -- though I suspect it would be quite difficult for the allies to
make a missile prematurely explode by jamming unless they had an
example of the missile, and therefore knew what signal to feed it.
Post by Eunometic
The allies incidently had a countermeasure to 'home on jam' in the
carpet II jammers, They had dozens of aircraft alternatly switching on
and off and frequency band shifting since they feared that German nigh
fighters would home in on the jamming siganls.
That sounds a good plan
Post by Eunometic
Post by c***@googlemail.com
1. release chaff to create multiple returns for the missiles to home in
on. This would work, however they would have to continually release
chaff all the way to Germany and back, which would take up weight that
could otherwise be used for bombs. Alternately, they could only release
the chaff when they detected radio illumination, however this would
rely on the chaff being spread widely about from the aircraft by the
time the missile is close, and there might not be anough time to do
that.
Progressively more advanced German countermeasures overcame
chaff/window for ground based radars. See my other post. It was more
of a problem for airborn radars at the time which required complicated
circuity to compensate for the relative motion. At best chaff would
reduce range and create an artificaly large target, a 'tail' that
disapperared as it slowed and that might seduce a missile to lock onto
an area behined the tail of the aircraft. Even if unsucesfull In
combination with noise and seduction jamming the accuracy of the
missile might be reduced sufficiently.
If the missiles could be cheaply mass-produced, perhaps they could be
fired in a salvo from a multiple-launch rocket assembly (something like
the 40 launcher assembly for the BM-21, for example). If the target was
something big and spread out like a bomber formation, this might be
effective.

I wonder if it woukld have been possible to fire the missile from an
88mm or 105mm or 128mm AA gun? Possibly not because the electronics
would be too delicate.

I vaguely remember reading somewhere of an effort to fire AA missiles
from modern 155 mm artillery.
Post by Eunometic
Post by c***@googlemail.com
4. an anti-radiation missile that homes in on the Germasn radio
transmitters. However, if they are only switched on for a short time,
with might be difficult to achieve
Indeed, the Wassefall missile had a similar gudience system to the V2
which incorporated an accelermoter. The difference being that
Wasserfall incorporated a full 3-axis system similar to that only
tested for advanced forms of the V2 to allow for the more complicarted
flight path. The missile would have flown under unjamable inertial
guidence in the initial phases of flight. This won't prevent jamming
but it will reduce warning and response time.
This would also be true of a missile initially fired from an AA gun, of
course.
Post by Eunometic
At Mach 3 the Wassefall would win out over the US anti radar missiles
which were at that time all based glide bombs or vertical gravity
bombs. The US did start a guided missile development program but (Hap
Arnold) they started several years latter. Incidently the Germans also
had a radar homming seeker called "Radischien" (raddish) that was
tested succesfully against a dummy radar on the Haggelkorn (Hailstsone)
glided bomb and was intended for Fritz-X. It was intended to attack
allied radars and LORAN navigation stations. I believe the test
missile hit the target within 5 meters.
2 meters according to my source.
Post by Eunometic
There are indeed plausible situation where they Germans could have
fielded a SAM missile in a timely fashion. Taking resources of the V2
was one such way. In General the several SAM missile developments
didn't receive sufficient priority till it was too late. The E4 Enzian
missile was actually 'provisionallly qualified for mass production'
according to Igor Witkowski writing in "Truth about the Wunderwaffe".
He also notes that the situation of the Reich in late 1944 made this
unrealistic.
There was an enormous proliferation of similar and almost-identical
systems within the reich, and also a lot of waste on weapons that
looked impressive but didn't do a lot (such as super-heavy artillery).
Peter Skelton
2006-12-31 20:41:20 UTC
Permalink
Post by c***@googlemail.com
Post by Eunometic
Post by c***@googlemail.com
Post by Henry J Cobb
The Allies had much better radar tech so could have trivally jammed such
a missile.
I'm sure they would have used ECM against it, but I doubt that jamming
would have been completely effective. It's relatively easy to jam a
weapon such as the Fritz-X, in which a radio signal sent control
messages to the missile; simply put out a more powerful signal on the
same frequency to drown outr the control signal.Fritz-X wasn't that easy to Jam and the jamming system that may have
worked relied upon investigation of captured of missiles. Hs 293 even
harder because, some usenet sources claim, it had more frequencies.
Certainly Kehl-Strasbourg command link had variations and there were
alternatives under development.
A SAM system kept only on German soil and not shipped to coastal France
(Bruneval raid) or Nth Africa or shipped to Italy like Frtiz-Xand
thereby vulnerable to captured is going to be very hard to compromise
in a timely fashion.
Yes. Although they may well have deployed it to France after D-Day.
Post by Eunometic
Secrecy is one of the keys, having another system or modification in
place for when it finally is compromised is the other. Relying purely
on building in jam resistence is likely to fail at some point. In this
area the allies tended to be philosophically ahead of the Germans.
At this stage in the war, didn't both sides automatically assume that
everything they did would be subject to counter measures, and plan for
counter-counter-measures accordingly?
Post by Eunometic
Post by c***@googlemail.com
But with the proposed system this won't work, because the missile would
home in on the jamming signal.
Home on jam is incorporated into modern missiles, eg AMRAAM. Due to
the difficult of jamming modern missiles disposable and towed decoys
are appearing.
Yes. bear in mind that modern missiles have microprocessors built in so
there is a wider range of behaviour they can do. A simple control
system for a WW2 missile, particularly if the unit cost is kept down,
isn't going to be able to do anything as sophisticated.
WWII allied heavies radiated like mad - they used radar
bomb-sights. A missile that homed on 3 and 9.8 cm emissions would
have been a brute (until oboe anyway)

Peter Skelton
Gordon
2007-01-03 01:43:13 UTC
Permalink
Post by Peter Skelton
WWII allied heavies radiated like mad - they used radar
bomb-sights. A missile that homed on 3 and 9.8 cm emissions would
have been a brute (until oboe anyway)
I thought it was OBOE first, then the radar bombsights?

v/r Gordon
Peter Skelton
2007-01-03 03:55:23 UTC
Permalink
Post by Gordon
Post by Peter Skelton
WWII allied heavies radiated like mad - they used radar
bomb-sights. A missile that homed on 3 and 9.8 cm emissions would
have been a brute (until oboe anyway)
I thought it was OBOE first, then the radar bombsights?
Nope.

Peter Skelton
Gordon
2007-01-03 06:07:16 UTC
Permalink
Post by Gordon
Post by Peter Skelton
WWII allied heavies radiated like mad - they used radar
bomb-sights. A missile that homed on 3 and 9.8 cm emissions would
have been a brute (until oboe anyway)
I thought it was OBOE first, then the radar bombsights?
Nope.
Peter, I would normally take your word for it - I know you to be
accurate in such matters. But in my research for my somewhat delayed
Mosquito book, I have a first-use of OBOE as 20 December 1942, with H2S
becoming available for heavies on 20 January 1943 and first used ten
days later - info I originally got from the RAF historical website.
That is not correct?

I am very interested in knowing if this is not accurate - last thing I
want to do is include bad info in my book.

v/r Gordon
Peter Skelton
2007-01-03 15:04:01 UTC
Permalink
Post by Gordon
Post by Gordon
Post by Peter Skelton
WWII allied heavies radiated like mad - they used radar
bomb-sights. A missile that homed on 3 and 9.8 cm emissions would
have been a brute (until oboe anyway)
I thought it was OBOE first, then the radar bombsights?
Nope.
Peter, I would normally take your word for it - I know you to be
accurate in such matters. But in my research for my somewhat delayed
Mosquito book, I have a first-use of OBOE as 20 December 1942, with H2S
becoming available for heavies on 20 January 1943 and first used ten
days later - info I originally got from the RAF historical website.
That is not correct?
I am very interested in knowing if this is not accurate - last thing I
want to do is include bad info in my book.
You are correct about first use.

OBOE, as first introduced was good for around 200 nm. It took
some time for it (and its descendants) to be useful far into
Europe, because stations on the European mainland were needed. We
were discussing the possibility of using some kind of
radar-homing missile to down heavies over Germany. In that
context, OBOE was much later than H2S.

I could have been clearer, my cryptic comment was not helpful.


Peter Skelton
Gordon
2007-01-04 03:16:34 UTC
Permalink
Post by Peter Skelton
Post by Gordon
I would normally take your word for it - I know you to be
accurate in such matters. But in my research for my somewhat delayed
Mosquito book, I have a first-use of OBOE as 20 December 1942, with H2S
becoming available for heavies on 20 January 1943 and first used ten
days later - info I originally got from the RAF historical website.
That is not correct?
I am very interested in knowing if this is not accurate - last thing I
want to do is include bad info in my book.
You are correct about first use.
OBOE, as first introduced was good for around 200 nm. It took
some time for it (and its descendants) to be useful far into
Europe, because stations on the European mainland were needed. We
were discussing the possibility of using some kind of
radar-homing missile to down heavies over Germany. In that
context, OBOE was much later than H2S.
I could have been clearer, my cryptic comment was not helpful.
Thanks for the clarification, Peter - you had me worried there! :)

v/r Gordon
The Leslie Cheswick Soul Explosion
2007-01-04 16:05:43 UTC
Permalink
Post by Gordon
Peter, I would normally take your word for it - I know you to be
accurate in such matters. But in my research for my somewhat delayed
Mosquito book, I have a first-use of OBOE as 20 December 1942, with H2S
becoming available for heavies on 20 January 1943 and first used ten
days later - info I originally got from the RAF historical website.
That is not correct?
I am very interested in knowing if this is not accurate - last thing I
want to do is include bad info in my book.
You're correct. At the risk of stating the obvious, I'd recommend
"Pathfinder Force. A History of 8 Group" by Gordon Musgrove which has
appendices on Oboe and H2S.

Gavin Bailey

--
Now see message: "Boot sector corrupt. System halted. All data lost."
Spend thousands of dollar on top grade windows system. Result better
than expected. What your problem? - Bart Kwan En
Eunometic
2007-01-01 11:20:20 UTC
Permalink
Post by c***@googlemail.com
Post by Eunometic
Post by c***@googlemail.com
Post by Henry J Cobb
The Allies had much better radar tech so could have trivally jammed such
a missile.
I'm sure they would have used ECM against it, but I doubt that jamming
would have been completely effective. It's relatively easy to jam a
weapon such as the Fritz-X, in which a radio signal sent control
messages to the missile; simply put out a more powerful signal on the
same frequency to drown outr the control signal.Fritz-X wasn't that easy to Jam and the jamming system that may have
worked relied upon investigation of captured of missiles. Hs 293 even
harder because, some usenet sources claim, it had more frequencies.
Certainly Kehl-Strasbourg command link had variations and there were
alternatives under development.
A SAM system kept only on German soil and not shipped to coastal France
(Bruneval raid) or Nth Africa or shipped to Italy like Frtiz-Xand
thereby vulnerable to captured is going to be very hard to compromise
in a timely fashion.
Yes. Although they may well have deployed it to France after D-Day.
Very dangerous if secrecy is an objective because of the possibillity
of allied-resistence espionage outside Germany. Such a missile is
needed well before d-day I think. Its functioning I suggest is to
create unacceptable losses for the Bomber command. In the case of the
USAF opperations the large warheads may have taken out an entire
formation and broken up the formation which then makes the bombers more
vulnerable. I suspect such missiles would be of less use against
fighter aircraft; who could out turn the missiles as they spotted them.
Post by c***@googlemail.com
Post by Eunometic
Secrecy is one of the keys, having another system or modification in
place for when it finally is compromised is the other. Relying purely
on building in jam resistence is likely to fail at some point. In this
area the allies tended to be philosophically ahead of the Germans.
At this stage in the war, didn't both sides automatically assume that
everything they did would be subject to counter measures, and plan for
counter-counter-measures accordingly?
The allies were at an advantage since they were in general on the
offensive leaving the germans the only option of responding to allied
initiatives.

German jamming of allied systems was less effective since they lacked
the sizeable bomber force to make this effective.

Allied strategy was to build in jam resistence but then also produce
radically different systems based on radical techniques on the
assumptions that the Germans would beging jamming after a particular
time period. Oboe for instance relied on short wave transmisions (to
which the Germans did develop jamming), then microwave, then it changed
to putting the transponder on the ground stations instead of the
aircraft. The germans jamed allied gun laying radar SCR-274 by which
time the allies were moving onto microwave radar eg SCR-584 for this
task. GEE gave way to LORAN etc.

The Germans developed an effectively unjamable navigation system known
as Bernhard (transmitter) and (Bernhardine) by transmitting a powerfull
broad band low frequency signal focused into a tight beam by a large
rotating antena. As the beam rotated it transmitted telemetry in the
form of both the current bearing of the antena and basic information on
the bomber stream to be interecepted. It however required a massive
ground based antena.

The basis for jam resistence I suggest is sequencing through
frequencies electromechanically in a sequence known to only the
transmitter and receiver. Within that the modulation scheme should be
robust as well.
Post by c***@googlemail.com
Post by Eunometic
Post by c***@googlemail.com
But with the proposed system this won't work, because the missile would
home in on the jamming signal.
Home on jam is incorporated into modern missiles, eg AMRAAM. Due to
the difficult of jamming modern missiles disposable and towed decoys
are appearing.
Yes. bear in mind that modern missiles have microprocessors built in so
there is a wider range of behaviour they can do. A simple control
system for a WW2 missile, particularly if the unit cost is kept down,
isn't going to be able to do anything as sophisticated.
In WW2 automationg was performed by mechanical or electromechanical
sequencers or perhaps piansola like tape.
Post by c***@googlemail.com
Post by Eunometic
I would sugggest that the home on jam would be best kept in the
illuminating radar to help it keep a lock rather than the missile due
to the complexity of such systems. Apart from noise jamming and
barrage jamming, there would be attempts to spoof with false delayed
echoes etc.
If the missile is only detecting the direction of the target, and not
the range, why bother to counteract the jamming? One reason might be if
the missile was also using the strength of the signal as a proximity
fuze -- though I suspect it would be quite difficult for the allies to
make a missile prematurely explode by jamming unless they had an
example of the missile, and therefore knew what signal to feed it.
Any jamming would likely be spoof jamming, to lead the missile astray,
or the break the lock by modulating the jamming to interfere with the
rotation rate of the spiral scaning of the radar tracker. Spiral
scaning is more vulnerable in this regard than monopulse.
Post by c***@googlemail.com
Post by Eunometic
The allies incidently had a countermeasure to 'home on jam' in the
carpet II jammers, They had dozens of aircraft alternatly switching on
and off and frequency band shifting since they feared that German night
fighters would home in on the jamming signals.
That sounds a good plan
Post by Eunometic
Post by c***@googlemail.com
1. release chaff to create multiple returns for the missiles to home in
on. This would work, however they would have to continually release
chaff all the way to Germany and back, which would take up weight that
could otherwise be used for bombs. Alternately, they could only release
the chaff when they detected radio illumination, however this would
rely on the chaff being spread widely about from the aircraft by the
time the missile is close, and there might not be anough time to do
that.
Progressively more advanced German countermeasures overcame
chaff/window for ground based radars. See my other post. It was more
of a problem for airborn radars at the time which required complicated
circuity to compensate for the relative motion. At best chaff would
reduce range and create an artificaly large target, a 'tail' that
disapperared as it slowed and that might seduce a missile to lock onto
an area behined the tail of the aircraft. Even if unsucesfull In
combination with noise and seduction jamming the accuracy of the
missile might be reduced sufficiently.
If the missiles could be cheaply mass-produced, perhaps they could be
fired in a salvo from a multiple-launch rocket assembly (something like
the 40 launcher assembly for the BM-21, for example). If the target was
something big and spread out like a bomber formation, this might be
effective.
EMW, the developers of the A4/V2 did work on the unguided "Taifun"
missile. It was liquid propelled, little bigger than an artillery
shell and unlike most anti-arcraft rockets of the day supposedly just
as accurate as FLAK despite lack of guidence. It was meant to be fired
in salvo.
Post by c***@googlemail.com
I wonder if it woukld have been possible to fire the missile from an
88mm or 105mm or 128mm AA gun? Possibly not because the electronics
would be too delicate.
The Americans developed minature valves that could survive a canon
launch and managed to squeeze 5 or 6 such vacuum tubes into an
artillery shell to create a radio proximity fuse. Basically if you
make something, like a vacuum tube 10 times smaller you make it 10
times more shock resistent. The US had its proximity fuse in
opperation by 1943.

So the electronics can be toughened, though I doubt the complexity
could be achieved.

The German canon launched proximty fuse was abandoned in 1940 but
actualy got to the point of 1000 or so succesfull test launches by the
end of 1944. The allied fuse used a continious wave emision; when an
object was was close it would cause a reflection. When the reflection
was strong enough and when the doppler shift occured the fuse would
detonate.

The German fuse used less electronics and relied instead on the
electrostatic change brought about by the aicrcraft. It had only half
the range (at best 14m) and degraded in wet weather but it in
priniciple it was highly jam resistent.

References are "Truth About the Wunderwaffen" by Igor Witowski who
cites "Proximity Fuse Development - Rheinmettal Borsig A.G.
Mullhausen. CIOS report ITEM nos 3 file nos XXVI -1 (1945)

I've also come across to other references
KUHGLOCKE, Electrostatic by Rhinemetall-Borsig. Intended for missiles.
Prototypes only.

KUHGLOCKEN, Smaller version designed for AA shells.

So this shows that the valves could be produced by the Germans.

The Germans did succesfully fire a few canon launched ramjet missiles
but not guidence was developed.

Although the Italians tested guided 76mm canon munitions in the 1970s I
don't know how this could be done.

I believe it is virtually impossible to make gyroscopes survice above
50g so the missile wouldn't know 'up'.
Post by c***@googlemail.com
I vaguely remember reading somewhere of an effort to fire AA missiles
from modern 155 mm artillery.
The "Tromsdorff Geschoss" or "Trommsdorff" missileof 105 and 155mm
calibre using carbon disulphide liquid as a fuel and ramjet. No
guidence developed I believe but achieved at least mach 3.
Post by c***@googlemail.com
Post by Eunometic
Post by c***@googlemail.com
4. an anti-radiation missile that homes in on the Germasn radio
transmitters. However, if they are only switched on for a short time,
with might be difficult to achieve
Indeed, the Wassefall missile had a similar gudience system to the V2
which incorporated an accelerometer. The difference being that
Wasserfall incorporated a full 3-axis system similar to that only
tested for advanced forms of the V2 to allow for the more complicarted
flight path. The missile would have flown under unjamable inertial
guidence in the initial phases of flight. This won't prevent jamming
but it will reduce warning and response time.
This would also be true of a missile initially fired from an AA gun, of
course.
Post by Eunometic
At Mach 3 the Wassefall would win out over the US anti radar missiles
which were at that time all based glide bombs or vertical gravity
bombs. The US did start a guided missile development program but (Hap
Arnold) they started several years latter. Incidently the Germans also
had a radar homming seeker called "Radischien" (raddish) that was
tested succesfully against a dummy radar on the Haggelkorn (Hailstsone)
glided bomb and was intended for Fritz-X. It was intended to attack
allied radars and LORAN navigation stations. I believe the test
missile hit the target within 5 meters.
2 meters according to my source.
Post by Eunometic
There are indeed plausible situation where they Germans could have
fielded a SAM missile in a timely fashion. Taking resources of the V2
was one such way. In General the several SAM missile developments
didn't receive sufficient priority till it was too late. The E4 Enzian
missile was actually 'provisionallly qualified for mass production'
according to Igor Witkowski writing in "Truth about the Wunderwaffe".
He also notes that the situation of the Reich in late 1944 made this
unrealistic.
There was an enormous proliferation of similar and almost-identical
systems within the reich, and also a lot of waste on weapons that
looked impressive but didn't do a lot (such as super-heavy artillery).
Some of the missile programs look like a waste of time, but when I've
looked closely I don't think they were illconceived or unrealistic for
the technology and abillity that was available. The programs suffered
severely from bombing, for instance the motors for the X-4 Air to Air
Missile were bombed to destruction. Walter Thiel was killed with his
whole family in an RAF raid and he could have advanced both the V2 and
Wasserfall program. Hardly a single one of the programs was not
distrupted severaly by bombing. SAM Missiles like the Hs 117 suffered
from an unbelievable number of quality roblems in the electronics that
got down to the manufacturing and resource problems that WW2 Germany
suffered from. Changing priorities, particularly in the period
1940-42, was another factor; this severely disrupted development of
some programs that could only be reastarted with great difficulty.

Some of the programs did suffer from technology that just wasn't ready.
The "Tonne" series of TV guidence systems were to big, bulky and
lacked light contrast yet by the time the 4th version was out it was
small. light, reliable and had an much more sensitive iconoscope
(probably and riesel-iconoscope that is 10 times more sensivtive).

Incidently both the Germans and the US was working on TV homing
missiles with autonomous lock on using image contrast methods. The
american seeker was for the VB-5.

The firm of Gollnow and Sohn of Stettin in conjunction with the firm
Fernseh
GmBH develop a 100-200 line spiral scan TV imager that could guide
itself on
to a ship born target; it seems to have worked when tested in
laboratory conditions.
More conventional man in loop systems however were pursued.
Detailed descritptions are apparently found in Dipl-Ing Fritz Muenster:
"A
Guidence System Using Television. AGARDograph 20, Verlag E Appelhans &
Co,
Brunswick, 1957, pp.135-161.

Probably the way this worked was to burn an TV image from an iconoscope
camera in the nose of the missile of the target on to a skiatron
picuture tube. The skiatron has halid salts instead of phosphors and
records a semi-permanent image that can be erased by heating via a 1
micron tungsten film. (Both the germans and allies used skiatrons for
radar plotting and recording osciliscopes). The actual recorded image
of the target is then scaned by an iconoscope while the actual image is
scaned as well. Slight ofsets in magnification, rotation and
displacement of the image are compared by the the process of cross
corelation. The electrical current signals of both actual and recorded
electron beam scans is multiplied in a special analog electronic
multiplier circuit or device (eg heptode) and then integrated in a
capacitor. The higest stored charge is the the best match.
Eunometic
2006-12-30 14:01:20 UTC
Permalink
Post by Henry J Cobb
Post by c***@googlemail.com
I'm aware that Nazi Germany had a number of SAM programmes, but I've
not read anything that suggests they tried the guidance method I have
The weapon system consists of the missile and a ground-based radio
transmitter that illuminates the target aircraft. The missile nose
contains 4 sensors that detect radio waves of the frequency of the
transmitter. One pair of sensors are placed so they differentially
detect radiation from the left or right side of the missile; these move
control fins to keep the missile pointing in a direction so that both
sensors detect the same amount of radiation (which will be when the the
missile is pointing directly at the target).
The Allies had much better radar tech so could have trivally jammed such
a missile.
I don't think you could rely on succesfull allied jamming at all since
the Germans were on to that partciular issue by then though your
opinion would be the most common one. The allies weren't that far
ahead in radar or signal processing in general. What they were ahead
in was microwave radar, something the Germans had ascertained by 1943
and corrected by having about 100 microwave FLAK radars in service by
the end of 1944 with a massive catchup program, starting in 1943, that
involved calling back over 1000 engineers and technicians from the
front and education school children in special schools as radar
opperators and technicians. As a result the allies were able to
opperate their equipment in the microwave field relatively unrestricted
for a while (the Germans did jam allied microwave radar and even
microwave versions of Oboes but its scale was to limited to make an
impact) while the German systems were under contiinous attack often by
hundreds of jammers.

Various 'doppler' moving target indicator techniques such as Wurzlaus,
Freylaus, Windlaus, Tastlaus, Nurenburg and the impressive but
experimental k-laus system was able to resolve window. The equipment
was ready within a few weeks of Window being used.

Various frequency changing techniques including the automatic "Full
Wismar" could avoid spot jamming.

The problem the Germans had in radar and never really overcame was
"Carpet" and especially "Carpet II" this was a broad band nose jammer
that jamed (from memory) about 25Mhz of bandwidth that derived its
noise from a gas discharge tube. Noise was filtered and to a tunable
frequency band. Machinary then swept through the frequencies, settling
on a band either randomly or in respone to a possbile radar and jamed
for 30 seconds before switching of and moving on. The Germans managed
to degrade Carpet I by Carpet II by concentrating its jamming was much
harder to deal with.

When done by hundreds of bombers broad band nooie jamming is very hard
to deal with even today.

However even there there is a possibillity. I'll send a link when I
have finished updating my PC. Basically "Vorschlage Number 2" from the
Kaiser Wilhelm institute proposed a system to compare the phase of a
main and a secondary delayed pulse using trapped accoustic delay lines.
By rejecting waveform of incorrect phase eg noise which by its nature
is random the jamming is rejected.

However jamming a control signal is much harder than a radar signal
since the receiver is receiving thousands of times more singal energy
than a radar receiver and it is difficult to jam in noise. The Fritz-X
and Hs 293 also had directional antena in the rear.

Mention must be made of the Kehl-Stassbourg guidence system supposedly
jammed on the Hs-293 anti-shipping missile and the Fritz-X. Initial
attempts to jam the bombs by information obtained by signals analysis
and intelligence doesn't seem to have been effective. The Germans
didn't think so. When crate loads of Fritz-X fell into allied hands
after the invasion of Italy they built jammers that finally may have
worked by jamming a particular control command signal.

The Germans never considered the systems jammed and never deployed the
more advanced "Kogge Brigge" system or the "Duran/Detmold FuG 208/238"
system that used 12km of 0.22mm wire that had been tested on the Hs
293B and was subsequently provisioned for retrofit into all production
Hs 293A. The Germans knew about techniques such as automatic frequency
changing etc.

The problem was simply that the carrier aircraft could not survive
alllied interceptors even with a 10 km stand off range.

A significant number of tracking microwaver radars entered service 1944
eg Rotterheim, a retrofit conversion of Manheim radar and there were
magnetrons with powers as high a 1MW in design and with wavelenths as
low as 1.5cm in low production (a dozen a day)

The real problem for the Germans was superior allied resources to
deploy new systems rapdiy. The allies grudginly respected Jerry and
developed systems that they knew would be jammed but would then be
replaced. For Gee they assumed only some 2-3 months of opperation.

The Germans initialy, as the receiver, tried to develop jam proof
systems. They succeded in the Bernhard/Bernahardine radio navigation
and telemetary system but in the case of the GEMA Jagdschloss Panoramic
(PPI) radar the performance was still degraded so much that the long
range warning function was compromised and only short range tracking
was possible.
Bernard Peek
2006-12-30 11:37:27 UTC
Permalink
Post by c***@googlemail.com
1. would a setup like this work, or am I missing something?
If it could be built then I think it would work.
Post by c***@googlemail.com
2. was the design I've described feasible with 1940's technology?
Don't think so. To be useful the system would need very sensitive
receivers in the missile and a highly directional radio transmitter,
which implies high frequencies. The allies had that technology at the
end of the war, the Germans didn't. So it might have been possible to
build a defence against the V2 with it, and that might have been
required if the war had lasted longer.
--
Bernard Peek
back in search of cognoscenti
Eunometic
2006-12-30 14:35:23 UTC
Permalink
Post by Bernard Peek
Post by c***@googlemail.com
1. would a setup like this work, or am I missing something?
If it could be built then I think it would work.
Post by c***@googlemail.com
2. was the design I've described feasible with 1940's technology?
Don't think so. To be useful the system would need very sensitive
receivers in the missile and a highly directional radio transmitter,
which implies high frequencies. The allies had that technology at the
end of the war, the Germans didn't. So it might have been possible to
build a defence against the V2 with it, and that might have been
required if the war had lasted longer.
The Wurburg radar had a 3m antena and with a 54cm wavelenth produced a
highly directional beam. In Wurzburg D, which has a conical scan to
aid the manual trackin, the accuracy could be 0.1mm and in the more
advanced Manheim (a trak lock 'version' of Wurburg gun layer of which
considerably less were produced because it used 100 valves) the
accuracy could be as high as 0.01 degree. This was not as good as the
allied SCR-584 which Wurzburg matched in range resolution but not in
angular but it was good enough.

The General solution was outsized antena eg Wurzburg Riesse(Giant) with
a 7m antena for both range and accuracy. Apparently a Manheim Reisse
was proposed for Wassefall guidence as it was decided to have a radar
accurate enough to pick out an individual aircraft in a formation. In
anycase by September 1944 "Rotterheim" radars based on magnetrons start
entering service and a series of more advanced micrwave radars is in
test eg Marburg/Egerland.
c***@googlemail.com
2006-12-31 20:10:00 UTC
Permalink
Post by Bernard Peek
Post by c***@googlemail.com
2. was the design I've described feasible with 1940's technology?
Don't think so. To be useful the system would need very sensitive
receivers in the missile and a highly directional radio transmitter,
which implies high frequencies. The allies had that technology at the
end of the war, the Germans didn't. So it might have been possible to
build a defence against the V2 with it, and that might have been
required if the war had lasted longer.
Do you have numbers for how sensitive the receivers would have to be,
and the limit of what the Germans could build?
Eunometic
2006-12-30 13:05:30 UTC
Permalink
Post by c***@googlemail.com
I've recently been thinking about a simple design for a surface-to-air
missile, of the sort that Germany could presumably have produced during
WW2. When I say simple I'm primarily refering to the guidance method,
since that is the hardest part of the missile to produce (unguided
rockets were used in the Napoleonic wars and probably earlier).
I'm aware that Nazi Germany had a number of SAM programmes, but I've
not read anything that suggests they tried the guidance method I have
They did indeed flight test a similar method on a Messerschmitt Enzian
variant. The guidence system was called "Moritz'.

The other systems was "Madrid" which was an crygoenically cooled
infrared homming recticle seeker that formed the basis of many post war
missiles.

Another system also "Archimedes" which was accoustic homming.

There were also variants of the Kehl (transmitter) and
Strasbourg(receiver) command guidence systems known for their use on
the Hs-293 and Fritz-X surface to ground missiles. This was a series
of guidence systems incidently so claiming they were jammable is not
quite right; new modulation techniques would have avoided the jamming
for a while. Incidently the system, tested on Wassefall, was not
manual but meant to be automatic.

I'm not sure if Moritz used a single rotating dipole spiral scan or 4
seperate antena as you postulate. The "mono-pulse" technique is far
better in avoiding lock breaking techniques but a little harder to
implement due to more components and their high level of calibration
and balance.

Incidently accoustic homming works quite well for subsonic targets; an
Me 262 could detect a 4 engined bombers direction out to 4 kilometers.
A jet was necessary as a prop would interfere.
Post by c***@googlemail.com
The weapon system consists of the missile and a ground-based radio
transmitter that illuminates the target aircraft. The missile nose
contains 4 sensors that detect radio waves of the frequency of the
transmitter. One pair of sensors are placed so they differentially
detect radiation from the left or right side of the missile; these move
control fins to keep the missile pointing in a direction so that both
sensors detect the same amount of radiation (which will be when the the
missile is pointing directly at the target).
The system you are describing is called SARH semi-active radar homming.
In your case it is not clear whether you are describing continious
wave illumination or radar pulse illumination.

in the case of illumination by radar pulse an antena in the rear of the
missile is needed so that the missile is primed to home on the targe
echo rather than the transmitter
Post by c***@googlemail.com
The other pair of sensors does the same thing, but are placed to
differentially detect radiation coming from above and below the
missile.
the control fins could work by acting aerodynamically on the airflow
around the moving missile; they could also
probably direct the direction of the exhaust of the rocket (a method
used in the V-2).
It is thus a SARH (semi-active radar homing) missile, where both the
missile and the ground installation can be made quite simple. The
ground installation is a radio transmitter able to trasnsmit an
unmodulated signal of a given wavelength (it would probably be best if
the signal is somewhat directional, which would give the system longer
ranger but require an operator to point it roughly at where the target
aircraft is). The four sensors in the missile need to be able to detect
radiation differently depending on where it is coming from; I presume
this could be done be shielding each of them in a ferrous box, with the
opening pointing at a different part of the sky for each sensor. (Note
that an American homing torpedo successfully used this guidance method
during WW2).
1. would a setup like this work, or am I missing something?
Yes, definetly
Post by c***@googlemail.com
2. was the design I've described feasible with 1940's technology?
Yes, definetly. The Germans had difficulty finding people and
resources to keep progressing these things at the required rate.
Keeping the quality of electronics in a missile up is extremely
difficult: a radar or radio can be repaired by technicians if it
arrives in a poor state in the case of a missile a much higher order of
reliabillity was required as it must work first time every time. The
Henschell Scmeterling SAM languised for lack of reliable valves and
radio sets, sabotage of impressed or foreign workers possibly factored
in as well.

The EMW Agregate 4 (i.e. V2) consumed much of the resources needed for
the SAM program. At the end Albert Speer wanted to redirect the
resources away from V2 production he had kept allive towards SAM
production but it was too late.

In the V2 clever systems engineering lead to a philosophy of
eliminating vacuum tubes wherever they were a single point of failure,
The Germans had developed to a high standard the technology of the
magnetic amplifier which was solid state, highly reliable and shock
resistent and powerfull. It was a little slow but that problem could
be overcome. It was found that relay contacts could replace
potentiometer pickups and be more or just as accurate.
Post by c***@googlemail.com
3. given that Nazi Germany had a large number of missile programmes,
why did they not try something like this? (Or perhaps they did and I'm
unaware of it)
Resources such as engineers, technicians, valve production etc were the
prime cause.

Missiles included EMW Wasserfall, Messersmcitt Enzian (E4 production,
E5 and area rule supersonic version) and a series of missiles under the
unbralla name "Rheintochter" as well as Henschells Hs 117.
Post by c***@googlemail.com
4. would a modernised version of the same design be feasible today? (I
expect you could make the missile more sophisticated and resistant to
jamming by making it microprocessor controlled)
5. have any SAMs like this ever been produced?
AFAIKT early US SAMS like Thumper and the first iteration of the Nike
were supposed to use beam riding. The problem was that the rocket
exhaust absorbed the radio wave and this solution did not work to well.
The more experienced Germans therefore carefully selected special
liquid propellants for Wasserfall to minimise this and used command
guidence backed up by terminal homming.

Generally beam riding requires jet propulsion or a quick burn engine
that coasts to target though the RN fielded sea slug for a while.

I think what you are describing is a continious wave or monopulse SARH
missile and they untill recently were the main kind of SAM guidence.
David Nicholls
2006-12-30 13:58:12 UTC
Permalink
Post by Eunometic
Generally beam riding requires jet propulsion or a quick burn engine
that coasts to target though the RN fielded sea slug for a while.
HMS Devonshire in service in 1962 to HMS Norfolk sold to the Chilieans in
1986 (without Sea Slug). I served on Devonshire and the Sea Slug Mk1 was a
very 1950's weapon - very simple and solid. Its biggest drawback was only
having one 901 tracking radar (therefore only one target engaged at one
time, although you could fire a slavo of two up the same beam) and very slow
missile handling system. It was, within its operating envelope, a very
relaible and accurate system. On more than one occasions the first missile
physically hit the target and teh second one went through the largest
remaining bit. (This was telemetry weapons against drones - that were meant
to be reusable). We did firings off Rooservelt Roads in 1973 when were the
escort to Ark Royal. I remember getting a lift on the base from one of the
drone controlers and when I said I was from the SeaSlug destroyer he said
"you are the guys that never miss!" Unfortunatly during the subesquent
firing trials we did!!

David
Eunometic
2006-12-30 14:22:04 UTC
Permalink
Post by David Nicholls
Post by Eunometic
Generally beam riding requires jet propulsion or a quick burn engine
that coasts to target though the RN fielded sea slug for a while.
HMS Devonshire in service in 1962 to HMS Norfolk sold to the Chilieans in
1986 (without Sea Slug). I served on Devonshire and the Sea Slug Mk1 was a
very 1950's weapon - very simple and solid. Its biggest drawback was only
having one 901 tracking radar (therefore only one target engaged at one
time, although you could fire a slavo of two up the same beam) and very slow
missile handling system. It was, within its operating envelope, a very
relaible and accurate system. On more than one occasions the first missile
physically hit the target and teh second one went through the largest
remaining bit. (This was telemetry weapons against drones - that were meant
to be reusable). We did firings off Rooservelt Roads in 1973 when were the
escort to Ark Royal. I remember getting a lift on the base from one of the
drone controlers and when I said I was from the SeaSlug destroyer he said
"you are the guys that never miss!" Unfortunatly during the subesquent
firing trials we did!!
David
Sea Slug was an impressive system. One day I'll put an effort in to
discovering how they solved the radar absorbtion problem in a solid
propellant. Believe it or not the http://www.aiaa.org actually have a
scholarly artcile on this problem.

http://pdf.aiaa.org/GetFileGoogle.cfm?gID=19240&gTable=mtgpaper

I loved those old British missile code mames such as "Green Cheese" or
"Purple Friend"
Henry J Cobb
2006-12-30 18:32:12 UTC
Permalink
Post by Eunometic
Post by c***@googlemail.com
3. given that Nazi Germany had a large number of missile programmes,
why did they not try something like this? (Or perhaps they did and I'm
unaware of it)
Resources such as engineers, technicians, valve production etc were the
prime cause.
Missiles included EMW Wasserfall, Messersmcitt Enzian (E4 production,
E5 and area rule supersonic version) and a series of missiles under the
unbralla name "Rheintochter" as well as Henschells Hs 117.
Information on some of these can be found at

http://www.luft46.com/missile/missile.html

-HJC
Jack Tingle
2006-12-30 16:08:14 UTC
Permalink
On 29 Dec 2006 23:37:59 -0800, "***@googlemail.com"
<***@googlemail.com> wrote:

...
Post by c***@googlemail.com
1. would a setup like this work, or am I missing something?
Probably not. The microwave radiation is too long wave and the
resolution of your sensors would be very poor at longer ranges, even
on a differential basis.

A variant of your idea is used for terminal guidance on some SAMs.
It's common in shorter range air-to-air missiles, where rotating
directional wave guides on a rolling airframe allow tracking, even
with poor resolution.
Post by c***@googlemail.com
2. was the design I've described feasible with 1940's technology?
Probably. It's similar to proximity fuse technology which only had to
measure distanace. It just wouldn't be accurate used alone.
Post by c***@googlemail.com
3. given that Nazi Germany had a large number of missile programmes,
why did they not try something like this? (Or perhaps they did and I'm
unaware of it)
Likely because they didn't think it would work. They invented command
guidance, which is still used for most large, radar guided SAMs.
Post by c***@googlemail.com
4. would a modernised version of the same design be feasible today? (I
expect you could make the missile more sophisticated and resistant to
jamming by making it microprocessor controlled)
Probably not, since the problem is the resolution, not the technology.
Post by c***@googlemail.com
5. have any SAMs like this ever been produced?
Probably only the adapted air-to-air missiles, like Sea Sparrow.
Again, true SAM's have used this for terminal guidance.

See Wikipedia if you want the details.

Regrets,
Jack Tingle
John Schilling
2007-01-02 13:41:35 UTC
Permalink
Post by c***@googlemail.com
I've recently been thinking about a simple design for a surface-to-air
missile, of the sort that Germany could presumably have produced during
WW2. When I say simple I'm primarily refering to the guidance method,
since that is the hardest part of the missile to produce (unguided
rockets were used in the Napoleonic wars and probably earlier).
I'm aware that Nazi Germany had a number of SAM programmes, but I've
not read anything that suggests they tried the guidance method I have
The weapon system consists of the missile and a ground-based radio
transmitter that illuminates the target aircraft. The missile nose
contains 4 sensors that detect radio waves of the frequency of the
transmitter. One pair of sensors are placed so they differentially
detect radiation from the left or right side of the missile; these move
control fins to keep the missile pointing in a direction so that both
sensors detect the same amount of radiation (which will be when the the
missile is pointing directly at the target).
Or when the missile is pointing exactly X, Y, or Z degrees left or
right of the target, where X, Y, and Z are values that you really
don't want to try and calculate using 1940s computing technology.

The wavelength of the standard German AAA fire control radar, which
is what I assume you'd be using for this purpose, is about half a
meter. The characteristic length of a heavy SAM nose cone, is about
half a meter. The incoming radio waves, are going to act like waves.
They will wrap around the missile, self-interfere, and trigger every
sensor simultaneously. And not necessarily in the obvious, "sensor
closest to the target gets the strongest signal" manner, either.


Oh, and even if you knew unambiguously what the direction to the
target was, "move the control fins to keep the missile pointing
at the target" is much easier said than done. Steering *towards*
the target, sure, that's easy. But how *much* to steer, so as not
to overshoot or undershoot, is tricky.

And pointing the missile towards the target, is not actually what
you want to do in the first place. What you want to do is point
the missile at the place where the target *will be* when the missile
gets there.

You can kind of brute-force the problem if your missile has a whole
lot of excess performance and a large proximity-fuzed warhead, but
you'll want to keep your expectations nice and low if you try that.
Post by c***@googlemail.com
The other pair of sensors does the same thing, but are placed to
differentially detect radiation coming from above and below the
missile.
Same problem as the first pair.
Post by c***@googlemail.com
the control fins could work by acting aerodynamically on the airflow
around the moving missile; they could also probably direct the direction
of the exhaust of the rocket (a method used in the V-2).
Supersonic aerodynamics are tricky and often counterintuitive, with some
notorious cases where aircraft with big power-assisted control surfaces
turned out to have roughly zero control authority once they went past
Mach 1. The thrust-vectoring bit you can at least test on the ground,
without losing a bird when you get it wrong.
Post by c***@googlemail.com
It is thus a SARH (semi-active radar homing) missile, where both the
missile and the ground installation can be made quite simple. The
ground installation is a radio transmitter able to trasnsmit an
unmodulated signal of a given wavelength (it would probably be best if
the signal is somewhat directional, which would give the system longer
ranger but require an operator to point it roughly at where the target
aircraft is). The four sensors in the missile need to be able to detect
radiation differently depending on where it is coming from; I presume
this could be done be shielding each of them in a ferrous box, with the
opening pointing at a different part of the sky for each sensor.
No; you're thinking of microwaves as if they were rays, which either
pass through the opening or they don't. Microwaves are, as the name
implies, waves, and their wave nature is quite significant at this scale.
If the opening is large enough to admit the waves at all, it will quite
cheerfully admit the waves that have flowed around the missile nose cone
and by unfortunate coincidence self-interfered constructively to produce
a double-strength signal right over the sensor pointed directly away from
the target. Watch missile go bye-bye.


If you insist on semi-active homing, you want your four sensors to be
simple dipole antennas projecting ahead of the missile nose cone, with
phase-comparison circuitry to interferometrically determine the (most
plausible) direction of the signal's origin. This I think is within
the reach of Nazi Radar Fu, but it's a lot more complicated than it is
probably worth.
Post by c***@googlemail.com
1. would a setup like this work, or am I missing something?
Several somethings, none of them insoluble but all of them tricky.
Post by c***@googlemail.com
2. was the design I've described feasible with 1940's technology?
The version you described, no. The modified version, barely.
Post by c***@googlemail.com
3. given that Nazi Germany had a large number of missile programmes,
why did they not try something like this? (Or perhaps they did and I'm
unaware of it)
They used beam-riding and radio command guidance instead, which were
good enough to get a fragmentation warhead within lethal distance of
a B-17 and much cheaper and easier to implement. And even they weren't
cheap and easy enough to get even a beta-test version into the field
before Nazi Science went down for the count.
Post by c***@googlemail.com
4. would a modernised version of the same design be feasible today?
5. have any SAMs like this ever been produced?
Plenty of semi-active radar guided SAMs have been produced. None of
them use the "four sensor/steer towards maximum signal" technique you
propose, because that doesn't work. So I guess it depends on whether
you consider using the more sophisticated techniques that do work, to
be "modernised versions of the same design".

I vaguely recall the US Navy's "Talos" long-range SAM using a four-probe
interferometer for terminal guidance, but don't quote me on that.
--
*John Schilling * "Anything worth doing, *
*Member:AIAA,NRA,ACLU,SAS,LP * is worth doing for money" *
*Chief Scientist & General Partner * -13th Rule of Acquisition *
*White Elephant Research, LLC * "There is no substitute *
****@spock.usc.edu * for success" *
*661-718-0955 or 661-275-6795 * -58th Rule of Acquisition *
David Nicholls
2007-01-02 18:33:17 UTC
Permalink
snip
Post by John Schilling
I vaguely recall the US Navy's "Talos" long-range SAM using a four-probe
interferometer for terminal guidance, but don't quote me on that.
I think that the UKs Sea Dart GWS30 uses a four probe interometer system.

David
Eunometic
2007-01-04 17:19:25 UTC
Permalink
Post by David Nicholls
snip
Post by John Schilling
I vaguely recall the US Navy's "Talos" long-range SAM using a four-probe
interferometer for terminal guidance, but don't quote me on that.
I think that the UKs Sea Dart GWS30 uses a four probe interometer system.
David
Direction finding on the German WW2 Lichtenstein radars with their
'stag antler aierials' of dipole reflector arrays was via a motor
driven mechanical device that switches in phase delays to the 4 aerials
groups.

In the SN-2 radar these became massive to allow long wavelenths to
minimise interference caused by Window but early versions had an array
of quite short dipoles.

In the "Morgenstern" (morning star) type aerials these became
cruciform, sort of like a christmass tree in the nose of the aircraft,
and could be covered with canvass, plastic or some other dielectric
material with only the tips of the aerials poking out.

So I think it would be possible to make a missile with relatively long
wavelenghts.

Paul J. Adam
2007-01-02 18:36:16 UTC
Permalink
Post by John Schilling
I vaguely recall the US Navy's "Talos" long-range SAM using a four-probe
interferometer for terminal guidance, but don't quote me on that.
The Royal Navy's Sea Dart has four polyrod aerials around the intake for
the same reason (and, conveniently, looks enough like a scaled-down
Talos that we can use the SIMDIS model for the Vandal :) )
--
The nation that makes a great distinction between its scholars and its
warriors, will have its thinking done by cowards and its fighting done
by fools.
-Thucydides


Paul J. Adam - mainbox{at}jrwlynch[dot]demon(dot)co<dot>uk
c***@googlemail.com
2007-01-03 01:25:06 UTC
Permalink
Post by John Schilling
Post by c***@googlemail.com
The weapon system consists of the missile and a ground-based radio
transmitter that illuminates the target aircraft. The missile nose
contains 4 sensors that detect radio waves of the frequency of the
transmitter. One pair of sensors are placed so they differentially
detect radiation from the left or right side of the missile; these move
control fins to keep the missile pointing in a direction so that both
sensors detect the same amount of radiation (which will be when the the
missile is pointing directly at the target).
Or when the missile is pointing exactly X, Y, or Z degrees left or
right of the target, where X, Y, and Z are values that you really
don't want to try and calculate using 1940s computing technology.
The wavelength of the standard German AAA fire control radar, which
is what I assume you'd be using for this purpose, is about half a
meter.
Possibly. I've no idea if other wavelengths were better suited or not.
(I don't have an electronics background).
Post by John Schilling
The characteristic length of a heavy SAM nose cone, is about
half a meter. The incoming radio waves, are going to act like waves.
They will wrap around the missile, self-interfere, and trigger every
sensor simultaneously. And not necessarily in the obvious, "sensor
closest to the target gets the strongest signal" manner, either.
Maybe it would be possible to cleverly design the antenna so you get
constructive interference from a signal coming from the "right"
direction, and destructive interference
Post by John Schilling
And pointing the missile towards the target, is not actually what
you want to do in the first place. What you want to do is point
the missile at the place where the target *will be* when the missile
gets there.
A simple solution to this is to get the missile to fly a constant
course to the target. Tilting the antennae structure slightly towards
the target 9to be done before the missile is in flight) would be a
quick-and-dirty way of doing this.
Post by John Schilling
You can kind of brute-force the problem if your missile has a whole
lot of excess performance and a large proximity-fuzed warhead, but
you'll want to keep your expectations nice and low if you try that.
Clearly the faster the missile is in relation to the target, the
better.
Post by John Schilling
Post by c***@googlemail.com
It is thus a SARH (semi-active radar homing) missile, where both the
missile and the ground installation can be made quite simple. The
ground installation is a radio transmitter able to trasnsmit an
unmodulated signal of a given wavelength (it would probably be best if
the signal is somewhat directional, which would give the system longer
ranger but require an operator to point it roughly at where the target
aircraft is). The four sensors in the missile need to be able to detect
radiation differently depending on where it is coming from; I presume
this could be done be shielding each of them in a ferrous box, with the
opening pointing at a different part of the sky for each sensor.
No; you're thinking of microwaves as if they were rays, which either
pass through the opening or they don't.
Not necessarily microwaves; would other radio frequencies be up to the
job?
Post by John Schilling
If you insist on semi-active homing, you want your four sensors to be
simple dipole antennas projecting ahead of the missile nose cone, with
phase-comparison circuitry to interferometrically determine the (most
plausible) direction of the signal's origin. This I think is within
the reach of Nazi Radar Fu, but it's a lot more complicated than it is
probably worth.
Certainly WW2 german aircraft were equipped with radars with dipole
antennae.
Post by John Schilling
Post by c***@googlemail.com
4. would a modernised version of the same design be feasible today?
5. have any SAMs like this ever been produced?
Plenty of semi-active radar guided SAMs have been produced. None of
them use the "four sensor/steer towards maximum signal" technique you
propose, because that doesn't work. So I guess it depends on whether
you consider using the more sophisticated techniques that do work, to
be "modernised versions of the same design".
What I mean by "modernised versions of the same design" is essensially
a SAM that uses cheap to manufacture apparatus for directing the
direction (and if possible, the range) of a radio signal, where the
radio transmitter is on the ground. Modern SAMs and AAMs typically cost
around $500k each, of which a good deal is the cost of the electronics.
Could it be done a lot more cheaply?
John Schilling
2007-01-04 03:04:55 UTC
Permalink
Post by c***@googlemail.com
Post by John Schilling
Post by c***@googlemail.com
The weapon system consists of the missile and a ground-based radio
transmitter that illuminates the target aircraft. The missile nose
contains 4 sensors that detect radio waves of the frequency of the
transmitter. One pair of sensors are placed so they differentially
detect radiation from the left or right side of the missile; these move
control fins to keep the missile pointing in a direction so that both
sensors detect the same amount of radiation (which will be when the the
missile is pointing directly at the target).
Or when the missile is pointing exactly X, Y, or Z degrees left or
right of the target, where X, Y, and Z are values that you really
don't want to try and calculate using 1940s computing technology.
The wavelength of the standard German AAA fire control radar, which
is what I assume you'd be using for this purpose, is about half a
meter.
Possibly. I've no idea if other wavelengths were better suited or not.
(I don't have an electronics background).
Then you probably ought not be trying to design radar-guided missiles;
it's going to be hard to even explain to you how and why you are wrong.

As far as other wavelengths being better, for this sort of thing you
generally want the shortest wavelength you can reasonably get. Which
for the Nazis was about fifty centimeters. Doing better than that,
required the cavity magnetron, which the Brits and Americans found to
be one step below Black Magic and which the Nazis never figured out
at all.
--
*John Schilling * "Anything worth doing, *
*Member:AIAA,NRA,ACLU,SAS,LP * is worth doing for money" *
*Chief Scientist & General Partner * -13th Rule of Acquisition *
*White Elephant Research, LLC * "There is no substitute *
****@spock.usc.edu * for success" *
*661-951-9107 or 661-275-6795 * -58th Rule of Acquisition *
Eunometic
2007-01-04 16:43:55 UTC
Permalink
Post by John Schilling
Post by c***@googlemail.com
Post by John Schilling
Post by c***@googlemail.com
The weapon system consists of the missile and a ground-based radio
transmitter that illuminates the target aircraft. The missile nose
contains 4 sensors that detect radio waves of the frequency of the
transmitter. One pair of sensors are placed so they differentially
detect radiation from the left or right side of the missile; these move
control fins to keep the missile pointing in a direction so that both
sensors detect the same amount of radiation (which will be when the the
missile is pointing directly at the target).
Or when the missile is pointing exactly X, Y, or Z degrees left or
right of the target, where X, Y, and Z are values that you really
don't want to try and calculate using 1940s computing technology.
The wavelength of the standard German AAA fire control radar, which
is what I assume you'd be using for this purpose, is about half a
meter.
Possibly. I've no idea if other wavelengths were better suited or not.
(I don't have an electronics background).
Then you probably ought not be trying to design radar-guided missiles;
it's going to be hard to even explain to you how and why you are wrong.
As far as other wavelengths being better, for this sort of thing you
generally want the shortest wavelength you can reasonably get. Which
for the Nazis was about fifty centimeters. Doing better than that,
required the cavity magnetron, which the Brits and Americans found to
be one step below Black Magic and which the Nazis never figured out
at all.
The Germans had 8kW 50cm magnetrons in test radars in 1940 and they had
18-22cm magnetrons on test benches. They were planning on tunable
magnetrons on the basis of a policy that all radars had to be tunable
but the program got cancelled in 1940 along with many others to devote
more resources to weapons that could be fielded as mass produced
systems within two years. The UK actualy directed a microwave shutdown
during the battle of Britain for the same reasons, though it was
unofficially and surrepticiously ignored.

Hans Hollman, the creator of GEMA who made the Wurzburg radar even had
a 1935 US patent for a water cooled multicavity magnetron.
http://www.radarworld.org/hans4.html

Ironically when the Germans discovered the H2S radar on a downed Shorts
Sterling in Feb 1943 they attributed the Magnetron to a British copy of
Russian patent. Over 1000 enginners and technicians were recalled to
catch up. They produced a copy within weeks and mounted it in the zoo
at Berlin, hence the name Berlin.

They introduced a number of Microwave Radars. Over 100 were in service
by Spetember 1944, mainly Rotterheim (a microwave conversion of the
Manheim/Wurzburg style of gun laying radar) but also Berlin search
types based on the British Magnetron but only with an electromagnet
instead of a permanent magnet. An automatic gun laying microwave radar
called Euklid was introduced on the Prinz Eugen as well.
Eunometic
2007-01-04 17:09:04 UTC
Permalink
Post by c***@googlemail.com
Post by John Schilling
The characteristic length of a heavy SAM nose cone, is about
half a meter. The incoming radio waves, are going to act like waves.
They will wrap around the missile, self-interfere, and trigger every
sensor simultaneously. And not necessarily in the obvious, "sensor
closest to the target gets the strongest signal" manner, either.
Maybe it would be possible to cleverly design the antenna so you get
constructive interference from a signal coming from the "right"
direction, and destructive interference
The Germans did test fly a semi-active radar hommer whose code name was
"Moritz" though they did have trouble with it. I've seen at least two
references to it. I'll give you a reference tommorow. It was one of
several guidence systems under development for Enzian.

I suggest that the way to do this would be to use a loop aeriel, simply
a coil of wire of the same kind used in radio direction finding loop
aerials in WW2 aircraft. The loop will produce the strongest signal
when it is perpendicular to the target direction.

However in order to steer the missile the loop aerial would need to be
mounted not flat in the nose of the missile but ofset by say 15 degrees
since the loop aerial can not differentiate between left and right.
The loop would then be spun around its axis. In its simplest form the
strenth of signal would slowly extend a control surface on the side the
rotating loop was tilted towards over several rotations. If the
missile was pinted in the correct direction the other side would match
it. In some case the rotation of the missile itself could be used.
The way to jam is to modulate a jamming signal to imitate the rotation
of the aerial.

The favoured german guidence system was to trak the target with one
radar, tract the missile via a beacon and calculate corrections via a
mechanical computer. (mech computers are very accurate) and send them
via radio command.

Both wassefall and Hs-117 were supposed to use this though Hs-117 would
have started out using a visual command link and proximity fuse.
Probaly good enough for 4 engined bombers in daylight.
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