Remote controled weapons in WWII

[Charles Gray]

Numerous bombers and heavy fighters, especially thowse that entered
service post 1943 have reference to remote controlled weapons.

Now, the remote control part should be fairly easy, but how were
they aimed? I'm assuming that you linked the gunners controls in such
a way thatthe gun always fired at the point where he was aiming,
making allowences for the location of the gun-- but how effective were
they? How hard was it to keep them in repair, as that sounds like a
fairly complex and advanced system for the 1940's.

[Kevin Brooks]

"Charles Gray" > wrote in message
...
> Numerous bombers and heavy fighters, especially thowse that entered
> service post 1943 have reference to remote controlled weapons.
>
> Now, the remote control part should be fairly easy, but how were
> they aimed? I'm assuming that you linked the gunners controls in such
> a way thatthe gun always fired at the point where he was aiming,
> making allowences for the location of the gun-- but how effective were
> they? How hard was it to keep them in repair, as that sounds like a
> fairly complex and advanced system for the 1940's.

The B-29 had remote controlled turrets. Each gunner (and the bombadier,
IIRC) had a computerized gun sight that he used to track the target. He was
required to be able to identify the target by aircraft type, as the wingspan
of the target had to be entered into the system in order for it to be
accurate. The information from his sight track went to the central fire
control computer which crunched the numbers (electromechanically) and
adjusted the guns under his control accordingly. The central fire control
gunner was perched in the rear dorsal blister, and he could switch control
of various turrets to the various gunners, who normally had primary control
of one particular turret.

It faced it s fair share of teething troubles during development, but it was
judged to be very effective during WWII (and even later, as the Soviets
copied the system for their Tu-4 Bull and then carried the same basic system
over for use in the later Tu-16 and Tu-20/95). My father trained as a B-29
gunner and flew missions over Japan--he had also trained on the B-17 and
B-24 with their manually operated guns, and he definitely considered the
B-29's system to be superior to those. During Korea the original system was
found wanting versus higher speed jet attacks; that should not have been a
big surprise, as B-29 crews facing early generation jets during training
towards the close of WWII had already reported that tracking the faster
interceptors was a real challenge (my dad's crew had rotated back stateside
to attend lead crew school before returning to Guam, and he had the
opportunity to particpate in such a training experiment out of what was then
Muroc AAF (later Edwards AFB).

Brooks

>

[William Donzelli]

"Emmanuel Gustin" > wrote in message >...

> It was technically quite difficult to provide a smooth control
> that had a more or less natural 'feel' for the gunner, was capable of
> high speeds of rotation but also of accurate slow tracking, and had
> no dead spots anywhere where movement wasn't linked correctly
> to control input -- for example when passing the 0 degree line from
> left to right, where the forces working on the turret reversed.

This I do not understand. The radar antennas of the era often used
synchro feedback systems - synchros do not have dead spots, they
provide a rotational signal from 0 to 360 with no interruptions when
making the 359 to 0 transition. What was the problem with the
control systems in the turrets?

> Very hard. The electronics of the period used numerous
> vacuum tubes which had a short lifetime.

Only hard working transmitter and radar tubes had short lifespans
(often just 50 hours). The tubes found in just about everything else
were quite hardy - most outlasted the war and are still good today.
Many small signal tubes often clocked lives well past 10,000 operating
hours.

William Donzelli

[George]

(William Donzelli) wrote in message >...
> "Emmanuel Gustin" > wrote in message >...
>
> > It was technically quite difficult to provide a smooth control
> > that had a more or less natural 'feel' for the gunner, was capable of
> > high speeds of rotation but also of accurate slow tracking, and had
> > no dead spots anywhere where movement wasn't linked correctly
> > to control input -- for example when passing the 0 degree line from
> > left to right, where the forces working on the turret reversed.
>
> This I do not understand. The radar antennas of the era often used
> synchro feedback systems - synchros do not have dead spots, they
> provide a rotational signal from 0 to 360 with no interruptions when
> making the 359 to 0 transition. What was the problem with the
> control systems in the turrets?
>

I am no expert, but I would guess he means the 0 degrees is the
bearing of the gun off the airplane's heading, in which case, the key
factor is the slipstream. All of a sudden all the stresses from the
slipstream switch from the left side of the turret to the right, or
vice versa. If the turret was supplying force to counter act the
slipstream's effects, it would need to change direction of that
force.

George

[Cub Driver]

Apart from the B-29, these weren't very sophisticated. The Boeing B-17
tail gunner aimed with a little stick; the guns tracked the movement
of the stick. The gunner at the rear of the Mitsubishi Ki-21 "Sally"
bomber had a manually aimed gun that was tracked by a stinger in the
tail. When his own rudder was in his sight, he could fire the stinger
by pulling on a lanyard. (Well, he could fire it at any time, but it
was most useful on those occasions.)

On Mon, 19 Jan 2004 20:57:21 GMT, Charles Gray > wrote:

>Numerous bombers and heavy fighters, especially thowse that entered
>service post 1943 have reference to remote controlled weapons.
>
> Now, the remote control part should be fairly easy, but how were
>they aimed? I'm assuming that you linked the gunners controls in such
>a way thatthe gun always fired at the point where he was aiming,
>making allowences for the location of the gun-- but how effective were
>they? How hard was it to keep them in repair, as that sounds like a
>fairly complex and advanced system for the 1940's.

all the best -- Dan Ford
email:

see the Warbird's Forum at www.warbirdforum.com
and the Piper Cub Forum at www.pipercubforum.com

[The Enlightenment]

"William Donzelli" > wrote in message
om...
> "Emmanuel Gustin" > wrote in
message >...
>
> > It was technically quite difficult to provide a smooth control
> > that had a more or less natural 'feel' for the gunner, was capable
of
> > high speeds of rotation but also of accurate slow tracking, and
had
> > no dead spots anywhere where movement wasn't linked correctly
> > to control input -- for example when passing the 0 degree line
from
> > left to right, where the forces working on the turret reversed.
>
> This I do not understand. The radar antennas of the era often used
> synchro feedback systems - synchros do not have dead spots, they
> provide a rotational signal from 0 to 360 with no interruptions when
> making the 359 to 0 transition. What was the problem with the
> control systems in the turrets?
>
> > Very hard. The electronics of the period used numerous
> > vacuum tubes which had a short lifetime.
>
> Only hard working transmitter and radar tubes had short lifespans
> (often just 50 hours). The tubes found in just about everything else
> were quite hardy - most outlasted the war and are still good today.
> Many small signal tubes often clocked lives well past 10,000
operating
> hours.
>
> William Donzelli



The tubes involved were special power amplifier tubes with heavy anode
cathode currents that must have been erosive. I do not believe they
had nearly 10,000 hours life. Amplifying DC was not possible because
directly unlike today when complimentary npn and pnp transistors are
available only valves were available and they had very particular
biasing requirements.

The technique of the day was to use an AC signal of 50,60 or 400Hz to
chop up the DC signal (called modulation) via a high speed relay known
as a vibrator. Typical life of these was 2000 hours. After being
chopped up the signal was transformer coupled to amplifier valves and
then demodulated by another relay similar to the first one and
operating in phase. This phase sensitive demodulation then restored
the chopped up signal to DC. Both relays chopped at the same time.
The phase sensitive modulation and demodulation could also be carried
out by a 4 valve ring modulator and ring demodulator. For reasons of
noise and power the modulation was carried out by a vibrator relay and
the phase sensitive demodulation by a valve based ring demodulator.

Its sounds crude but was quite accurate. A full serve system would
involved resistors for position sensing that were amplified in DC,
amplidynes which operated in AC to generate mathematical functions
such as sine, cos etc (amplidyne is a sort of rotary transformer in
which the overlap of the poles of the two secondary windings are
added/subtracted from each other. The area of he poles can be used to
generate voltages that are functions of shaft position.

The noble prize winner William Schokley who's team invented the
transistor was I believe funded in part to provide replacements for
valve gear in B29 barrettes.

During the Korean war the electromechanical computers of the B29 could
not compute for the closing rates of the MiG 15s. I don't see how
they would have coped with an Me 262 in that case.

I guess that Aiming consisted of tracking the target while enclosing
the wingspan of the aircraft in a "ring" in the gun sight to estimate
range. The "rate" and range determined lead and elevation.

[Peter Stickney]

In article >,
Charles Gray > writes:
> Numerous bombers and heavy fighters, especially thowse that entered
> service post 1943 have reference to remote controlled weapons.
>
> Now, the remote control part should be fairly easy, but how were
> they aimed? I'm assuming that you linked the gunners controls in such
> a way thatthe gun always fired at the point where he was aiming,
> making allowences for the location of the gun-- but how effective were
> they? How hard was it to keep them in repair, as that sounds like a
> fairly complex and advanced system for the 1940's.

There were quite a few implementation of remote-controlled weapons
during WW 2. The level of sophistication varied greatly - from fixed
light machine guns pointing directly behind some bombers that couldn't
cover that area with aimed gune - (HE 111, and, IIRC, the Martin
Maryland - it worked about as well as could be expected, which is to
say, not very well at all) - to the U.S. A-26 and B-29's computer
controlled systems that automatically computed lead, jump, drop, and
the effects of altitude and temperature on the gun's trajectory, and
could aim several gun turrets from a single sighting station. (Oh,
yeah, it corrected for parallax errors for having the turrets adn the
sights in different locations. A B-29 gunner only had to place the
pipper of his sight on the target, and adjust the stadiametric range
circle as he tracked. The Fire COntrol System did the rest.

Remote control was also a feature of AAA (Anti-Aircraft Artillery).
All combatants used this to some degree, eslecially for Medium &
Heavy (40mm & up) guns. Targets were tracked by radar or optical
systems, which fed the target's motion and position data to a
Mechanical or Electromechanical Analog Computer, which resolved the
pointing solution and time of flight (Fuze setting) solution for the
guns. Less sophisticated systems, such as those used by the Germans,
used the computer to move a set of pointers on the gun mounts, and the
Pointer and Trainer operators turned handwheels to move the gun's
position to match the computer's commands. The U.S., and later the
Brits, with better technology (Feedback control systems, Variacs adn
Amplidynes) were able to control the pointing of the guns, and the
setting of the fuzes directly. With the introduction of the SCR-584
autotracking (You lock it on to a target, and it tracks it
automatically) radar, which fed the Ballistic Computer directly,
Remote Power Control to the guns, and Proximity Fuzes, Anti-aircraft
engagements were completely automated - The Gun Crew's job was to feed
shells into the breech as fast as they could, and act as a backup to
the remote systems.

The U.S. Navy had a similar level of sophistication. All guns on a
large ship were remotely controlled in train & elevation by the Fire
Control Systems, and the firing of the guns was controlled by the
computer. These computers automatically tracked the designated
targets, and controlled rangefinders and pointing systems, as well as
the guns. (The Spotting and Rangefinding crews, once the system was
tracking, input corrections, rather than raw position inputs)
With the introduction of microwave radars, which could spot
shell splashes as well as track targets, and allow gunfire corrections
to be made, they were capable of completely blind fire. THis was a
significant advantage that no other combatant had. (The Brits came
close, but the Germans and the Japanese were never able to build
systems that could accurately position something as large as a 90mm
gun, let alone a Battleship Turret).

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

[Kevin Brooks]

"Peter Stickney" > wrote in message
...
> In article >,
> Charles Gray > writes:
> > Numerous bombers and heavy fighters, especially thowse that entered
> > service post 1943 have reference to remote controlled weapons.
> >
> > Now, the remote control part should be fairly easy, but how were
> > they aimed? I'm assuming that you linked the gunners controls in such
> > a way thatthe gun always fired at the point where he was aiming,
> > making allowences for the location of the gun-- but how effective were
> > they? How hard was it to keep them in repair, as that sounds like a
> > fairly complex and advanced system for the 1940's.
>
> There were quite a few implementation of remote-controlled weapons
> during WW 2. The level of sophistication varied greatly - from fixed
> light machine guns pointing directly behind some bombers that couldn't
> cover that area with aimed gune - (HE 111, and, IIRC, the Martin
> Maryland - it worked about as well as could be expected, which is to
> say, not very well at all) - to the U.S. A-26 and B-29's computer
> controlled systems that automatically computed lead, jump, drop, and
> the effects of altitude and temperature on the gun's trajectory, and
> could aim several gun turrets from a single sighting station. (Oh,
> yeah, it corrected for parallax errors for having the turrets adn the
> sights in different locations. A B-29 gunner only had to place the
> pipper of his sight on the target, and adjust the stadiametric range
> circle as he tracked. The Fire COntrol System did the rest.

I just got off the phone with my eighty year old father. While he was fuzzy
on the specifics these many years later, he said that they had to input the
wingspan of the target into the computer at the gunner's station (otherwise
your system could not compute the range). The navigator input the B-29's
current airspeed into the CFC system from his location. The gunner then
tracked the target in his reticle, adjusting the stadia as you indicate. He
could not recall any requirment for temperature to be input.

Brooks

[M. J. Powell]

In message >, The
Enlightenment > writes
>
>"William Donzelli" > wrote in message
om...
>> "Emmanuel Gustin" > wrote in
>message >...
>>
>> > It was technically quite difficult to provide a smooth control
>> > that had a more or less natural 'feel' for the gunner, was capable
>of
>> > high speeds of rotation but also of accurate slow tracking, and
>had
>> > no dead spots anywhere where movement wasn't linked correctly
>> > to control input -- for example when passing the 0 degree line
>from
>> > left to right, where the forces working on the turret reversed.
>>
>> This I do not understand. The radar antennas of the era often used
>> synchro feedback systems - synchros do not have dead spots, they
>> provide a rotational signal from 0 to 360 with no interruptions when
>> making the 359 to 0 transition. What was the problem with the
>> control systems in the turrets?
>>
>> > Very hard. The electronics of the period used numerous
>> > vacuum tubes which had a short lifetime.
>>
>> Only hard working transmitter and radar tubes had short lifespans
>> (often just 50 hours). The tubes found in just about everything else
>> were quite hardy - most outlasted the war and are still good today.
>> Many small signal tubes often clocked lives well past 10,000
>operating
>> hours.
>>
>> William Donzelli
>
>
>
>The tubes involved were special power amplifier tubes with heavy anode
>cathode currents that must have been erosive. I do not believe they
>had nearly 10,000 hours life. Amplifying DC was not possible because
>directly unlike today when complimentary npn and pnp transistors are
>available only valves were available and they had very particular
>biasing requirements.

Most of the valves were similar to civilian valves, some were
'ruggedised'. Radio and TV valves had lives longer than 10,000 hours.

Mike
--
M.J.Powell

[Peter Stickney]

In article >,
"Kevin Brooks" > writes:
>
> "Peter Stickney" > wrote in message
> ...
>> In article >,
>> Charles Gray > writes:
>> > Numerous bombers and heavy fighters, especially thowse that entered
>> > service post 1943 have reference to remote controlled weapons.
>> >
>> > Now, the remote control part should be fairly easy, but how were
>> > they aimed? I'm assuming that you linked the gunners controls in such
>> > a way thatthe gun always fired at the point where he was aiming,
>> > making allowences for the location of the gun-- but how effective were
>> > they? How hard was it to keep them in repair, as that sounds like a
>> > fairly complex and advanced system for the 1940's.
>>
>> There were quite a few implementation of remote-controlled weapons
>> during WW 2. The level of sophistication varied greatly - from fixed
>> light machine guns pointing directly behind some bombers that couldn't
>> cover that area with aimed gune - (HE 111, and, IIRC, the Martin
>> Maryland - it worked about as well as could be expected, which is to
>> say, not very well at all) - to the U.S. A-26 and B-29's computer
>> controlled systems that automatically computed lead, jump, drop, and
>> the effects of altitude and temperature on the gun's trajectory, and
>> could aim several gun turrets from a single sighting station. (Oh,
>> yeah, it corrected for parallax errors for having the turrets adn the
>> sights in different locations. A B-29 gunner only had to place the
>> pipper of his sight on the target, and adjust the stadiametric range
>> circle as he tracked. The Fire COntrol System did the rest.
>
> I just got off the phone with my eighty year old father. While he was fuzzy
> on the specifics these many years later, he said that they had to input the
> wingspan of the target into the computer at the gunner's station (otherwise
> your system could not compute the range). The navigator input the B-29's
> current airspeed into the CFC system from his location. The gunner then
> tracked the target in his reticle, adjusting the stadia as you indicate. He
> could not recall any requirment for temperature to be input.

I should have been more clear, I guess. The computer used an OAT and
barometric pressure reading in its solution, but that was read by its
own thermometer and anaeroid. The Gunners didn't have to dial it in.
They did have to set the baseline for the range reticle, as you
describe.


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

[Eunometic]

(Peter Stickney) wrote in message >...
> In article >,
> Charles Gray > writes:
> > Numerous bombers and heavy fighters, especially thowse that entered
> > service post 1943 have reference to remote controlled weapons.
> >
> > Now, the remote control part should be fairly easy, but how were
> > they aimed? I'm assuming that you linked the gunners controls in such
> > a way thatthe gun always fired at the point where he was aiming,
> > making allowences for the location of the gun-- but how effective were
> > they? How hard was it to keep them in repair, as that sounds like a
> > fairly complex and advanced system for the 1940's.
>
> There were quite a few implementation of remote-controlled weapons
> during WW 2. The level of sophistication varied greatly - from fixed
> light machine guns pointing directly behind some bombers that couldn't
> cover that area with aimed gune - (HE 111, and, IIRC, the Martin
> Maryland - it worked about as well as could be expected, which is to
> say, not very well at all) - to the U.S. A-26 and B-29's computer
> controlled systems that automatically computed lead, jump, drop, and
> the effects of altitude and temperature on the gun's trajectory, and
> could aim several gun turrets from a single sighting station. (Oh,
> yeah, it corrected for parallax errors for having the turrets adn the
> sights in different locations. A B-29 gunner only had to place the
> pipper of his sight on the target, and adjust the stadiametric range
> circle as he tracked. The Fire COntrol System did the rest.

Several more sophisticated German systems existed.

1 Cleverly positioned cheek babettes on the Me 410.
2 The Ju 388 has a remotely controlled tail turret that had a duel
view persicope with ventral and dorsal optics for a single gunner who
could scan above and below the aircraft. It was ofset to avoid the
tail. (It was similar system to that of the A26 I believe)
3 The Heinkel He 177 had a single remote dorsal turret.
4 A Piaggio P.108 4 engined bomber had barbettes on the nacells. (I
think only a dozen entered service but they gave sterling sevice to
the Lufwaffe who captured them)
5 The FA13 system on the, Arado 240 and Arado Ar 440. (It had a
system called the FA13 with a periscope)
(The Ar 240/440 was to have an electric system but was switched to a
hydraulic one becuase of reliablity. The gunners reported difficulty
in spotting the attacking aircraft in the ventral view in time during
testing. I do not know if this problem was ever solved by anyone with
episcopes and wide angle optics including on the A26 or latter Ju 388)

6 The Ju 288 (a few of which entered service) had tail, chin/vental
and dorsal barbettes.

Some of the German systems had computing abillity that extended beyond
mere elevation.

In a fast aircraft that can be only intercepted in a tail chase these
periscopes probably make sense.



Those that missed out on service:
7 The Australian CA-11 WOOMERA (alson known as Wackett bomber, was
designated the CAC-CA-4)
8 The Bell XB42 Mixmaster. (Guns beautifull streamlined between
airlerons and flaps)
9 B36

The B29 unlike the B36 was weird because the sighting stations and
guns were so far offset that the computers had to compensate.

The B36 doesn't even seem to have a tail gunner?

>
> Remote control was also a feature of AAA (Anti-Aircraft Artillery).
> All combatants used this to some degree, eslecially for Medium &
> Heavy (40mm & up) guns. Targets were tracked by radar or optical
> systems, which fed the target's motion and position data to a
> Mechanical or Electromechanical Analog Computer, which resolved the
> pointing solution and time of flight (Fuze setting) solution for the
> guns. Less sophisticated systems, such as those used by the Germans,
> used the computer to move a set of pointers on the gun mounts, and the
> Pointer and Trainer operators turned handwheels to move the gun's
> position to match the computer's commands. The U.S., and later the
> Brits, with better technology (Feedback control systems, Variacs adn
> Amplidynes) were able to control the pointing of the guns, and the
> setting of the fuzes directly.

The Germans had computing and servo systems for their ships.
Considering the extreme state of manpower shortages I can not see that
the use of the fully automatic systems could be justified. The
precision servo systems for the tens of thousands of German FLAK
systems would be impossible to build and service.

AFAIK see a flak predictor on the basis of a fusion of inputs from
sound, stereoscopic range finders, radar produces a firing solution as
to where the target aircarft will be in say 15 seconds and provides
elevation, azimuth, fuse timing and firing time data.

A fully servo opperated system would shave of a few seconds since the
servo could position the gun faster than the point and crank
opperators (giving the aircrat less time to evade) and save some
manpower however they would also require extra skilled manpower to
manufacture and service.

By this time the Germans were using 13 year olds and retirees to
opperate the FLAK.

I think designing such systems and building a few was well within
Germanies technical know how. Manufacturing in quantity would have
been beyond them.

The FLAK predictor computers were afterall already providing
milliampmeter signals to the display guages on the guns. The
American guns used big 100lb or so caste iron variable resistors/
potentiometers that must have taken a long time to machine and then
calibrate to the precision required. Add in the backlash free
gearboxes, servo motors and amplifiers and you have a task beyond the
scope of Germanies resources to supply and maintain in quantity in
quick time at least.

> With the introduction of the SCR-584
> autotracking (You lock it on to a target, and it tracks it
> automatically) radar, which fed the Ballistic Computer directly,
> Remote Power Control to the guns, and Proximity Fuzes, Anti-aircraft
> engagements were completely automated - The Gun Crew's job was to feed
> shells into the breech as fast as they could, and act as a backup to
> the remote systems.
>
> The U.S. Navy had a similar level of sophistication. All guns on a
> large ship were remotely controlled in train & elevation by the Fire
> Control Systems, and the firing of the guns was controlled by the
> computer. These computers automatically tracked the designated
> targets, and controlled rangefinders and pointing systems, as well as
> the guns. (The Spotting and Rangefinding crews, once the system was
> tracking, input corrections, rather than raw position inputs)
> With the introduction of microwave radars, which could spot
> shell splashes as well as track targets, and allow gunfire corrections
> to be made, they were capable of completely blind fire. THis was a
> significant advantage that no other combatant had. (The Brits came
> close, but the Germans and the Japanese were never able to build
> systems that could accurately position something as large as a 90mm
> gun, let alone a Battleship Turret).

Not quite completley correct. The early German systems would servo
azimuth to a computer. The complication of servoing elevation being
considered pointless and not worth the effort becuase of the ranging
systems used involved braketing the target in anycase.

[William Donzelli]

"The Enlightenment" > wrote in message >...

> The tubes involved were special power amplifier tubes with heavy anode
> cathode currents that must have been erosive. I do not believe they
> had nearly 10,000 hours life. Amplifying DC was not possible because
> directly unlike today when complimentary npn and pnp transistors are
> available only valves were available and they had very particular
> biasing requirements.

While I am not doubting your explanation of the turrets electronics, I
must wonder what the engineers were drinking back then. They obviously
did not talk much with the radar folks.

In many WW2 era radars (ship, ground, and air), vibrators are not
used. In fact, garden variety 6L6 tubes (of guitar amp fame, these
days) were a favorite, used to vary the field windings in some sort of
motor-generator (Amplidynes were used, even back to the pre-War Navy
CXAM days, but there were some other types).

This was a very good system - responsive, accurate, and able to swing
an antenna around that was much heavyier than the turrets on an
airplane. Why did the aircraft gun people not use this technology
until later?

> During the Korean war the electromechanical computers of the B29 could
> not compute for the closing rates of the MiG 15s. I don't see how
> they would have coped with an Me 262 in that case.

This problem was also around in other tracking radar computers.

William Donzelli

[William Donzelli]

"The Enlightenment" > wrote in message >...

> Its sounds crude but was quite accurate. A full serve system would
> involved resistors for position sensing that were amplified in DC,
> amplidynes which operated in AC to generate mathematical functions
> such as sine, cos etc (amplidyne is a sort of rotary transformer in
> which the overlap of the poles of the two secondary windings are
> added/subtracted from each other. The area of he poles can be used to
> generate voltages that are functions of shaft position.

By the way, I think you are confusing "Amplidyne" with "Synchro" and
"Selsyn". An Amplidyne is a special motor-generator that basically
acts like a magnetic amplifier - vary the fields a little and get a
larger change on the output. A Synchro (or Selsyn) is what you mean -
a rotary transformer that can transmit angular data electrically
(generally with three wires as multiphase AC). The things that can
generate the sine and cosine from an angular shaft position are called
"Synchro Resolvers".

William Donzelli