B-29 computer guided turrets

How exactly did they work? Could the turrets be fired independently at
multiple targets? What crew members controlled them? etc? etc?

In article ,
"William Anderson" writes:
How exactly did they work? Could the turrets be fired independently at
multiple targets? What crew members controlled them? etc? etc?

There were turrets in 5 locations - Upper Forward, Upper Aft,
Lower Forward, lower Aft, and the Tail. A;; turrets were power
operated, including teh tail.
There were 5 Gunner's Stations on the aircraft -
the Upper Gunner, who had a dome on top of the fuselage in the Aft
Pressurized Compartment, and who acted as the coordinatoe.
The Bombardier-Gunner, with a sight in the extreme nose.
The Right and Left Side Gunners, with domes on wither side of the Aft
Pressurized Compartment,
The Tail Gunner, in a small pressurized cabn in the extreme tail.

All Gunners hy gyroscopic lead computing sights with stadiametric
ranging. As the Gunner tracked teh target, the gyroscopes measured
the rate of movement of the target in Azimuth and Elevation, The
Gunner would also track teh target in range, by using a "Motorcycle
throttle" type grip in the sight to size a ring of dots in the sight
picture to match the airplane's wingspan. Since the wingspan of an
attacking fighter would be known, or estimated slose enough, this
would give Range and Range Rate (Closing speed) information to hte
sight.

The sights fed their Azimuth/ Elevation/Range and Az/El/Range Rate
data to the Central Fire COntrol computer, which was an
electromechanical analog computer that would take the sight's data,
the firing airplanes' current environment - (Altitude, Speed, Outside
Air Temp, and produce a Firing Solution for that target. The computer
sent teh xontrol signals to the turrets, which aimed the guns to
correct for Lead, Gravity Drop, Jump, and the firing airplane's
motion.

Most sighting stations could control more than one turret.
The Upper Gunner controlled both Foreward and Aft Upper Turrets.
The Bombardier normally controlled the Lower Forward Turret.
The 2 Side Gunners could trade off control of the Lower Aft Turret.
The Tail Gunner controlled the Tail Turret.
The Tail Gunner and Bombardier-Gunner each had deadman switches on
their sights. If they did not have the deadman switch held cloased,
their turrets (Lower Forward and Tail) could be controlled by the Side
Gunners. The two Side Gunners had a switch box between them that would
control which Side Station controlled the three turrets.
Each sighting station could aim independantly, adn whichever turrets
were available to that station when a target was designated would
track and fire at teh target that the station was tracking.

It was an amazing system, and once the original bugs were worked out,
it worked quite well. The CFC system was also used on the B-50, which
was basically an uprated B-29 with P&W R4360 engines.
While the basic principals of remotely-controlled turrets and a
computing sighting system was used on the B-36, teh B-36's gunners
didn't control multiple turrets. (I don't know why for certain, but
I'll bet that the -36 was so large that a Gunner just didn't have
enough of a field of view to make it worthwhile.
The B-45, B-47, and B-52, and B-66 all had only tail guns, radar aimed and
computer controlled. On the B-47, the Gunner was the Copilot, who had
the turret controls and radar displays on hte aft bulkhead of teh
cockpit. His ejection seat swivelled around so that he was facing aft
when he was working the guns. The other jets ahd dedicated gunners.

Hope this helps.

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

(Peter Stickney) wrote in message ...

All Gunners hy gyroscopic lead computing sights with stadiametric
ranging. As the Gunner tracked teh target, the gyroscopes measured
the rate of movement of the target in Azimuth and Elevation, The
Gunner would also track teh target in range, by using a "Motorcycle
throttle" type grip in the sight to size a ring of dots in the sight
picture to match the airplane's wingspan. Since the wingspan of an
attacking fighter would be known, or estimated slose enough, this
would give Range and Range Rate (Closing speed) information to hte
sight.

To add to this fine explanation, starting right around the beginning
of 1945, AN/APG-15 radars started making there way in B-29s. This was
a fairly small, cheap set that took much of the guesswork for figuring
range out of the gunners hands (although they could always go back to
the manual method, especially when the radars broke down).

--
William Donzelli

"William Donzelli" wrote in message
om...
(Peter Stickney) wrote in message
...

All Gunners hy gyroscopic lead computing sights with stadiametric
ranging. As the Gunner tracked teh target, the gyroscopes measured
the rate of movement of the target in Azimuth and Elevation, The
Gunner would also track teh target in range, by using a "Motorcycle
throttle" type grip in the sight to size a ring of dots in the sight
picture to match the airplane's wingspan. Since the wingspan of an
attacking fighter would be known, or estimated slose enough, this
would give Range and Range Rate (Closing speed) information to hte
sight.

To add to this fine explanation, starting right around the beginning
of 1945, AN/APG-15 radars started making there way in B-29s. This was
a fairly small, cheap set that took much of the guesswork for figuring
range out of the gunners hands (although they could always go back to
the manual method, especially when the radars broke down).

True, but the radars were only installed on the B models during WWII,
meaning that they were largely limited to use by IIRC the 315th BW. The
remainder (and vast majority) of the Superfort fleet soldiered on with the
purely optical system. Note that the 315th BW is apparently the major source
of the oft-repeated apocryphal tale that all the B-29's had their guns
(except for tail mount) stripped and went into battle with reduced crews at
Lemay's behest; apparently that might have been the case for the 315th, or a
goodly portion of it, but little evidence exists that any of the other bomb
wings followed suit.

Brooks


--
William Donzelli

"William Anderson" wrote in message ...
How exactly did they work? Could the turrets be fired independently at
multiple targets? What crew members controlled them? etc? etc?

From 'Flying Guns: World War 2 - Development of Aircraft Guns,
Ammunition and Installations 1933-45' by Emmanuel Gustin and myself:

"The B 29 finally appeared with five turrets: Front upper, front
lower, aft upper, aft lower, and tail turret; as initially foreseen
the tail also had a 20 mm cannon in addition to the twin .50"s. The
tail guns were exclusively controlled by the tail gunners in his own
compartment, but the other guns were operated from four sighting
stations, one in the nose and three in a compartment aft of the wing.
Each gunner could simultaneously operate two turrets, as the situation
of the moment demanded. The "master gunner" was the upper gunner in
the aft compartment, and he assigned turrets to gunners with his
control panel.

The gunners had to track the attacking aircraft from their sighting
stations, which had a reflector gunsight that generated signal outputs
by a "Selsyn" system. An analog computer used the elevation, azimuth
and range inputs from the gunner to calculate the lead and the
parallax compensation, and aimed the gun turret with an Amplidyne
drive unit. The computer took into account the effects the air
density, the airspeed and the angle of the guns relative to this
airspeed had on the bullet trajectory. A factor that could not be
taken into account was the flexibility of the bomber's fuselage
itself, and its tendency to expand or shrink locally as temperature
varied. These caused a variable misalignment between the sighting
station and the gun turret. The heating effect was large enough to
make alignment of the guns on a butt outdoors, exposed to the sun,
impracticable. The guns had to be harmonised indoors to meet
specifications."

Tony Williams
Military gun and ammunition website: http://www.quarry.nildram.co.uk
Discussion forum at: http://forums.delphiforums.com/autogun/messages/

"Tony Williams" wrote in message
m...
"William Anderson" wrote in message
...
How exactly did they work? Could the turrets be fired independently at
multiple targets? What crew members controlled them? etc? etc?

From 'Flying Guns: World War 2 - Development of Aircraft Guns,
Ammunition and Installations 1933-45' by Emmanuel Gustin and myself:

"The B 29 finally appeared with five turrets: Front upper, front
lower, aft upper, aft lower, and tail turret; as initially foreseen
the tail also had a 20 mm cannon in addition to the twin .50"s. The
tail guns were exclusively controlled by the tail gunners in his own
compartment, but the other guns were operated from four sighting
stations, one in the nose and three in a compartment aft of the wing.
Each gunner could simultaneously operate two turrets, as the situation
of the moment demanded. The "master gunner" was the upper gunner in
the aft compartment, and he assigned turrets to gunners with his
control panel.

Actually, I believe his title was "fire control gunner". I believe you are
correct in stating that the tail gunner was the only crewmember who could
fire the tail guns.


The gunners had to track the attacking aircraft from their sighting
stations, which had a reflector gunsight that generated signal outputs
by a "Selsyn" system. An analog computer used the elevation, azimuth
and range inputs from the gunner to calculate the lead and the
parallax compensation, and aimed the gun turret with an Amplidyne
drive unit.

As Peter has already pointed out, the gunner also had to dial in the
wingspan of the attacking aircraft (gunners spent a significant amount of
time training on Japanese aircraft recognition and corresponding wingspan
data); the navigator input the airspeed and air temperature data into the
system.

Brooks

The computer took into account the effects the air
density, the airspeed and the angle of the guns relative to this
airspeed had on the bullet trajectory. A factor that could not be
taken into account was the flexibility of the bomber's fuselage
itself, and its tendency to expand or shrink locally as temperature
varied. These caused a variable misalignment between the sighting
station and the gun turret. The heating effect was large enough to
make alignment of the guns on a butt outdoors, exposed to the sun,
impracticable. The guns had to be harmonised indoors to meet
specifications."

Tony Williams
Military gun and ammunition website: http://www.quarry.nildram.co.uk
Discussion forum at: http://forums.delphiforums.com/autogun/messages/

"Tony Williams" wrote in message
m...

From 'Flying Guns: World War 2 - Development of Aircraft Guns,
Ammunition and Installations 1933-45' by Emmanuel Gustin and myself:

"The B 29 finally appeared with five turrets: Front upper, front
lower, aft upper, aft lower, and tail turret; as initially foreseen
the tail also had a 20 mm cannon in addition to the twin .50"s. The
tail guns were exclusively controlled by the tail gunners in his own
compartment, but the other guns were operated from four sighting
stations, one in the nose and three in a compartment aft of the wing.
Each gunner could simultaneously operate two turrets, as the situation
of the moment demanded. The "master gunner" was the upper gunner in
the aft compartment, and he assigned turrets to gunners with his
control panel.

The gunners had to track the attacking aircraft from their sighting
stations, which had a reflector gunsight that generated signal outputs
by a "Selsyn" system. An analog computer used the elevation, azimuth
and range inputs from the gunner to calculate the lead and the
parallax compensation, and aimed the gun turret with an Amplidyne
drive unit. The computer took into account the effects the air
density, the airspeed and the angle of the guns relative to this
airspeed had on the bullet trajectory. A factor that could not be
taken into account was the flexibility of the bomber's fuselage
itself, and its tendency to expand or shrink locally as temperature
varied. These caused a variable misalignment between the sighting
station and the gun turret. The heating effect was large enough to
make alignment of the guns on a butt outdoors, exposed to the sun,
impracticable. The guns had to be harmonised indoors to meet
specifications."

When the Soviets reverse-engineered the Tu-4 BULL from the B-29, how
successful were they at copying such systems?
--
Andrew Chaplin
SIT MIHI GLADIUS SICUT SANCTO MARTINO
(If you're going to e-mail me, you'll have to get "yourfinger." out.)

"Andrew Chaplin" wrote in message
...
"Tony Williams" wrote in message
m...

From 'Flying Guns: World War 2 - Development of Aircraft Guns,
Ammunition and Installations 1933-45' by Emmanuel Gustin and myself:

"The B 29 finally appeared with five turrets: Front upper, front
lower, aft upper, aft lower, and tail turret; as initially foreseen
the tail also had a 20 mm cannon in addition to the twin .50"s. The
tail guns were exclusively controlled by the tail gunners in his own
compartment, but the other guns were operated from four sighting
stations, one in the nose and three in a compartment aft of the wing.
Each gunner could simultaneously operate two turrets, as the situation
of the moment demanded. The "master gunner" was the upper gunner in
the aft compartment, and he assigned turrets to gunners with his
control panel.

The gunners had to track the attacking aircraft from their sighting
stations, which had a reflector gunsight that generated signal outputs
by a "Selsyn" system. An analog computer used the elevation, azimuth
and range inputs from the gunner to calculate the lead and the
parallax compensation, and aimed the gun turret with an Amplidyne
drive unit. The computer took into account the effects the air
density, the airspeed and the angle of the guns relative to this
airspeed had on the bullet trajectory. A factor that could not be
taken into account was the flexibility of the bomber's fuselage
itself, and its tendency to expand or shrink locally as temperature
varied. These caused a variable misalignment between the sighting
station and the gun turret. The heating effect was large enough to
make alignment of the guns on a butt outdoors, exposed to the sun,
impracticable. The guns had to be harmonised indoors to meet
specifications."

When the Soviets reverse-engineered the Tu-4 BULL from the B-29, how
successful were they at copying such systems?

Apparently rather successful--the same system was later used on their Tu-16
as well, IIRC.

Brooks

--
Andrew Chaplin
SIT MIHI GLADIUS SICUT SANCTO MARTINO
(If you're going to e-mail me, you'll have to get "yourfinger." out.)

"Kevin Brooks" wrote in message
...

Apparently rather successful--the same system was later used on their
Tu-16
as well, IIRC.

The Soviets did not need to copy the gun aiming system, as selsyn aiming was
used in battle ships by 1920. Follow Stickney's lead and stick to cut and
paste Kevin.

(Tony Williams) wrote in message om...
"William Anderson" wrote in message ...
How exactly did they work? Could the turrets be fired independently at
multiple targets? What crew members controlled them? etc? etc?

From 'Flying Guns: World War 2 - Development of Aircraft Guns,
Ammunition and Installations 1933-45' by Emmanuel Gustin and myself:

"The B 29 finally appeared with five turrets: Front upper, front
lower, aft upper, aft lower, and tail turret; as initially foreseen
the tail also had a 20 mm cannon in addition to the twin .50"s. The
tail guns were exclusively controlled by the tail gunners in his own
compartment, but the other guns were operated from four sighting
stations, one in the nose and three in a compartment aft of the wing.
Each gunner could simultaneously operate two turrets, as the situation
of the moment demanded. The "master gunner" was the upper gunner in
the aft compartment, and he assigned turrets to gunners with his
control panel.

Tony, while this is by and large true, I have to disagree
on a couple of points.
From the B-29 Crew Training Manual, paraphrased:
Yes, the Upper Gunner was the Master Gunner, responsible for
coordinating the fire of the other gunners. There were two control
circuits for the turrets, however. The Primary Control circuits
were hard wired, and, as long as teh appropriate deadman switches
were held down, had control of their turrets as described in my
other post in this thread. The Secondary Channels were controlled
from a switch box that was on the pedestal of the Upper Gunner's
"Barber Chair", and was more accessible by the Side Gunners
"Downstairs". (Not a big point, really - it would be foolish to
have the controls only accessible by one crewman.)

If you examine the Turret COntrol switchbox, you'll see that there
is a channel for control of the tail turet by either of the
Side Gunners. (As it happens, there's an image of the Turret
Control channels, and the switch box, in the "Neat B-29 stuff"
section of Zeno's Warbirds:

http://www.zenoswarbirdvideos.com/Im...pics/TCS44.gif

--
Pete Stickney