Remote controled weapons in WWII

"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

(William Donzelli) wrote in message . com...
"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

"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.

In message , The
Enlightenment writes

"William Donzelli" wrote in message
. com...
"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

"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

"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