Eunometic wrote:
You'll find that there were at least two other allied photoelectric
based fuses. The first one entered service on rockets (it couldn't
handle the shock of a gun launch) but its photocells found
application
in the punched paper tape reader of the colossus machine used in
decrypting Enigma. The second system could withstand a cannon
lauch
and entered service. It used a torrodial perspex lens around the
circumference or rim of the shell that focused on a photocell.

To be fair most of these German fuses were for different purposes
than
cannon shell launch. Missiles need more sophisticated and jam
resistent radio proximity fuses. In addition the Germans were
clearly
hedging their bets by developing a spread of systems to reduce their
exposure to Allied Jamming attempts. The German were big investors
in
both passive and active infrared technology and this was begining to
pay of in 1945.

In part the plethora of projects represents the secrecy
compartmentalisation, as well as intersevice rivalries but also a
policy of phased development was in place so that the Germans could
catch up and stay ahead in areas such as radar.

In reality relying on one proximity fuze type is a recipe for
disaster.
The allies relied on secrecy and then the hope that the Germans
couldn't react in time.

The Wasserfall and Enzian Surface to Air missiles for instance had a
spread of guidence and proximity fuze systems under development.
Wasserfall had a 3 axis gyroscopic version of the two axis gyroscopic
guidence system in the V2 including apparently the PIGA
accelerometer.
Even without external guidence it would have placed itself within a
few
hundred meters of its target. There an infrared terminal homing
system
was to be used (Madrid), or alternatively command guidence using a
radar called "Mannheim" (80 of these track-lock entered service) or
visual command guidence. There was also a semi active guidence
system
under development called "Moritz". The command link was based on a
specially developed version of the "Khel/Strassbourg" system used on
Fritiz-X and Hs 293 but also on a purpose built system called
"Kogge/Brigge"

SNIP

See the US guided and glider bomb programs for a similar list of
proposed and experimented with guidance systems (VB/BG series)

Fletcher BG-1
After the USAAF had cancelled the order for the Fletcher PQ-11A
radio-controlled target drone, ten of the PQ-11As under construction
were completed as XBG-1 bomb gliders. In the XBG-1, the PQ-11A's engine
was replaced by a 900 kg (2000 lb) bomb. The XBG-1 was to be towed to
the target area by a larger aircraft and upon release was to be guided
to target impact by radio-commands using imagery transmitted from a TV
camera in the glider's nose. No information on the XBG-1 test program
is available, but the model was never used operationally.

Fletcher BG-2
When the Frankfort CG-1 troop-carrying glider was cancelled in 1941,
the three XCG-1s under construction were completed by Fletcher as XBG-2
bomb gliders. No information about the bomb load or the results of
tests (if any!) is available, but the BG-2 program was cancelled in
1942.

Cornelius BG-3
The BG-3 was a design with nose-mounted horizontal stabilizers and
forward-swept wings. As such it was possibly similar to Cornelius'
XFG-1 fuel glider. Although the USAAF had planned to procure one XBG-3
prototype, this order was cancelled in 1942

The VB designation was introduced by the U.S. Army Air Force in 1943,
and covered unpowered guided bombs with effectively no standoff gliding
range (i.e. "vertical" bombs).

ATSC VB-1/VB-2 Azon
In April 1942, the USAAF's Materiel Command (became part of ATSC (Air
Technical Service Command) in 1944) began the development of the Azon
family of guided bombs. The initial variant, designated VB-1, was based
on a 450 kg (1000 lb) bomb (initially the M44, but later models
apparently switched to the standard AN-M65), which was modified with a
new tail unit. The latter consisted of a gyroscopic unit to provent the
bomb from rolling, a flare for optical tracking, an octagonal shroud
with control surfaces, and a radio-command receiver. When a VB-1 was
dropped, the bombardier could track it through his bombsight and use a
joystick-type control to send corrective commands to the bomb. The Azon
guidance system allowed only lateral course corrections, but errors in
range could not be corrected (hence the name Azon = "Azimuth Only").

The Azon development phase ended in late 1943, and the VB-1 was
subsequently ordered into mass production. The second Azon variant was
the heavier VB-2, which was based on a 900 kg (2000 lb) bomb, but that
version was apparently not produced in very large numbers. The first
VB-1/2 bombs were sent to Europe in February 1944, and a total of 15000
Azons were produced until November 1944.

Because of their azimuth-only guidance, the VB-1 was particularly
suited to long and narrow targets (like bridges or railways) where
range errors would be irrelevant. For "normal" targets, however, the
VB-1 was actually not as good as unguided free-fall bombs, because a
bomber could not break away immediately after dropping the bomb, and
the accuracy was effectively not increased because of the lack of range
control. Another peculiarity of the Azon guidance set was the fact that
only five different radio channels were available for the command link,
meaning that not more than five bombs could be controlled
independently. Although in theory a whole group of bombs using the same
command channel could be controlled simultaneously, this was not
practical. The accuracy of all but the "primary" bomb (i.e. the one
which was tracked by the bombardier) in such a group was rather bad,
because the non-spinning Azon bombs showed a significant dispersion.

The drawbacks of the Azon meant that its use remained very limited.
However, it was employed rather successfully in Burma, where it was
used to destroy very vital and therefore heavily defended bridges along
the Japanese supply lines. Less the 500 Azons were needed to destroy 27
bridges.

When the war ended, the USAAF quickly removed the VB-1 and VB-2 from
its inventory. Because of the much reduced post-war funding, the USAAF
limited its guided vertical bomb research to the more advanced
VB-3/VB-4 Razon family.

ATSC VB-3/VB-4 Razon
In parallel with the Azon tests, the ATSC also developed a more
advanced variant called Razon, which was to be controllable in both
range and azimuth. The designations VB-3 and VB-4 were assigned to the
450 kg (1000 lb) and 900 kg (2000 lb) Razon versions, respectively. The
Razon guidance kit had two octagonal shrouds in a tandem arrangement.
The most problematic part in Razon development was to build a suitably
modified bombsight, which would allow the bombardier to correctly judge
the bomb's deviation in range so that the range control could be used
effectively. The Razon also had an improved radio-command link with 47
separate channels, effectively eliminating the Azon's problems with
concurrent drops by a multitude of bombers.

The VB-3/VB-4 was combat-ready in summer 1945, and about 3000 Razons
were subsequently produced, but none of them were used before World War
II was over. However, the VB-3 was operationally tested five years
later during the first months of the Korean War. B-29 aircraft, which
could carry eight VB-3s, dropped several hundred Razons on North Korean
bridges, and although the overall reliability of the bombs was rather
low, some targets were actually destroyed. However, in general multiple
hits by the small the 450 kg (1000 lb) bombs were needed to destroy a
large bridge span, and the USAF's use of guided bombs for these special
missions switched to the much larger VB-13/ASM-A-1 Tarzon.

ATSC VB-5
The VB-5 was a 450 kg (1000 lb) bomb, which used the same tandem
octagonal control shroud arrangement as the VB-3/VB-4 Razon. However,
the VB-5 was not command guided but used an autonomous light contrast
seeker. This bomb did not go into production, presumably because the
guidance mechanism didn't work as planned.

ATSC VB-6 Felix
The VB-6 Felix was a 450 kg (1000 lb) bomb with an octagonal control
shroud and a heat seeking device in the nose. Intended for use against
strong infrared emitters (like e.g. blast furnaces), the VB-6 was
tested with some success during 1945, but the program was cancelled at
the end of World War II. The U.S. Navy developed a very similar
IR-guided bomb as the ASM-N-4 Dove.

ATSC VB-7, VB-8
The VB-7 and VB-8 both used a TV/radio-command guidance, where a TV
camera in the bomb's nose transmitted the image to a display set for
the bombardier, who could then correct the bomb's course by
radio-commands. The weights of the VB-7/VB-8 are unclear, but it can be
assumed that these two guided bombs were cancelled early in the
development phase.

Douglas VB-9/VB-10/VB-11/VB-12 Roc
The Roc series of guided bombs was developed by Douglas, the MIT and
the NDRC (National Defense Research Committee). The VB-9 model was a
450 kg (1000 lb) bomb with cruciform wings and fins and a radar seeker
in the nose. The radar image was transmitted to the bombardier who
could use it to direct the bomb's path by radio commands. However, the
radar was often useless because of ground clutter, and the VB-9 program
was terminated in early 1945.

VB-9
The later Roc models all used a 450 kg (1000 lb) bomb body of 61 cm (24
in) diameter and 3 m (10 ft) length. They were fitted with two circular
shrouds, a larger one which could move around two axes for directional
steering, and a smaller one in the tail designed to slow down the bomb
to facilitate the tracking and guidance task of the bombardier. The
VB-10 had a TV camera and transmitter, so that the bombardier could
track the bomb via the image on his TV display set. The VB-11 had an
infrared seeker for autonomous heat-seeking guidance, and the VB-12 was
tracked visually (making it similar in operation to the VB-3/VB-4
Razon).

VB-10/11/12
The VB-10 (and presumably also the VB-11/VB-12 models) was tested
between September 1944 and May 1945, when the Roc program was
terminated without any model going into production.

Bell VB-13 Tarzon
The VB-13 is discussed on a separate page about the VB-13/ASM-A-1
Tarzon.

Specifications
The few available data on the dimensions and weights of the VB-series
bombs are mentioned in the main text






http://www.designation-systems.net/d...pp1/index.html

http://www.wpafb.af.mil/museum/arm/vb.htm





The smaller Ruhrstahl X-4 wire guided Air to Air missile opperated
with
basic wire guidence and a contact fuse backed up accoustic proximity
fuse called "Kranich". A accoustic terminal homing system "Dogge"
was
also under development as was an infrared terminal homing system and
proxitmity fuse. The same systems were planed for the Enzian missile
including an accoustic homing head called "Archimedes"

The accoustic homing systems worked quite well. A Me 262 Jet
equiped
with accoustic homing systems could detect a bomber and its
directions
to about 4-5 miles range.

SNIP

I'm sorry, but I find an acoustic system that sensitive, yet able to
filter out the wind noise of going 500 mph, along with the howl of two
turbojets a bit hard to believe. Could you provide more details or a
citation?