1553 bus on the C-130?

Does the C-130 have two 1553 buses onboard? One for flight control
and one for EW/mission systems?

Thanks in advance,
Dave

I thought it was the No.1 via kings cross!!? lol

--
"Fire at will"
Which one's will?! Do you know these people????
"David Harper" wrote in message
om...
Does the C-130 have two 1553 buses onboard? One for flight control
and one for EW/mission systems?

Thanks in advance,
Dave

"David Harper" wrote in message
om...
Does the C-130 have two 1553 buses onboard? One for flight control
and one for EW/mission systems?

I don't think 1553 is used for flight control since the latency and speed
isn't sufficient. Mission systems may well use it though. I think by nature
1553 is dual-redundant so that's where you might get the idea of two from.
Not familiar with the C-130 personally though.

Si

In article ,
(David Harper) wrote:

Does the C-130 have two 1553 buses onboard? One for flight control
and one for EW/mission systems?

Depends on the model of C-130.
Some have 1553 for non-essential avionics such as ECCM and Comms.

--
Harry Andreas
Engineering raconteur

In article , "Simon Robbins"
wrote:

"David Harper" wrote in message
om...
Does the C-130 have two 1553 buses onboard? One for flight control
and one for EW/mission systems?

I don't think 1553 is used for flight control since the latency and speed
isn't sufficient. Mission systems may well use it though. I think by nature
1553 is dual-redundant so that's where you might get the idea of two from.
Not familiar with the C-130 personally though.

1553 has no inherent connection with dual-redundancy.
In fact, 1553 is usually used as a single bus.

--
Harry Andreas
Engineering raconteur

Definitely not used for flight controls. If you have ever been in a 130
and looked up you saw lots of cables that connect to actuators that run the
flight controls. Now the MC-130E has a 1553 bus for systems. I suspect the
MC-130H has two, for redundant systems. The C-130J might have more than
one, because of the FADEC and all the systems.

Les Matheson
F-4C(WW)/D/E/G(WW), AC-130A, MC-130E WSO/EWO (ret)

"Simon Robbins" wrote in message
...
"David Harper" wrote in message
om...
Does the C-130 have two 1553 buses onboard? One for flight control
and one for EW/mission systems?

I don't think 1553 is used for flight control since the latency and speed
isn't sufficient. Mission systems may well use it though. I think by
nature
1553 is dual-redundant so that's where you might get the idea of two from.
Not familiar with the C-130 personally though.

Si




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Simon Robbins wrote:

I don't think 1553 is used for flight control since the latency and speed
isn't sufficient.

It is sufficient for the B-2 flight control system, which is totally
dependent on MIL-STD-1553B data buses for reading the air data ports
and commanding the hydraulic actuators. (The stick and pedal position
transducers are not on the buses; they are wired directly to the
flight control computers.)

During ground testing I've transferred 700,000 bps through a 1553 bus
from the B-2 cockpit area out to a flight control actuator terminal in
one of the wings. That figure is net data throughput, i.e., it doesn't
count the command and status words, parity bits, etc. And it's not
necessarily the maximum capacity. I never had an opportunity to
experiment and find the limits of the bus, though I believe 700,000
bps must be pretty close.

That throughput was attained between test sets connected to the bus; I
have no idea how much bandwidth the B-2 flight control system uses in
normal operation.

There are about 32 MIL-STD-1553B data buses on a B-2. Four are
dedicated to flight controls.

I've never even been aboard a C-130, except maybe at an air show
static display, so I can't answer the original poster's question. But
I can confirm that the 1553 bus does have enough speed for fly by wire
flight controls on a large airplane.

--

Paul Hirose
To reply by email delete INVALID from address.

On Fri, 11 Jun 2004 14:06:45 -0700, (Harry
Andreas) wrote:

In article , "Simon Robbins"
wrote:

"David Harper" wrote in message
om...
Does the C-130 have two 1553 buses onboard? One for flight control
and one for EW/mission systems?

I don't think 1553 is used for flight control since the latency and speed
isn't sufficient. Mission systems may well use it though. I think by nature
1553 is dual-redundant so that's where you might get the idea of two from.
Not familiar with the C-130 personally though.

1553 has no inherent connection with dual-redundancy.
In fact, 1553 is usually used as a single bus.

Yep - the spec allows for x-redundancy. Although you'd want to keep a
lid on the amount of redundancy :

More redundancy = more resilience
More redundancy = more bits = more cost.

After a while, the law of diminishing returns comes in, making it daft
to have too many redundant legs. Dual would make a big improvement in
resilience, Triple would be a partial improvement over dual but after
triple, you're probably getting into gold-plating levels. It also
depends on how much space there is. If you do your dual redundance
with the cables in the same runs, you're only effectively getting
single redundancy cos a cut in one place will cut both cables.

Pete Lilleyman

(please get rid of ".getrid" to reply direct)
(don't get rid of the dontspam though ;-)

In message - "Simon Robbins"
writes:

"David Harper" wrote in message
. com...
Does the C-130 have two 1553 buses onboard? One for flight control
and one for EW/mission systems?

I don't think 1553 is used for flight control since the latency and speed
isn't sufficient. Mission systems may well use it though. I think by nature
1553 is dual-redundant so that's where you might get the idea of two from.
Not familiar with the C-130 personally though.

Si



In flight control systems tolerable delays are so large by todays computers
standards than it's hardly an issue: for example, such an agile fighter as
F-16 feels OK with about 1/2 second delay between the stick input and control
surface movement. The fastest type of signal is stabilization augmentation -
the control surface can oscilate at frequencies from somewhat below 8Hz in
F-4E to something like 20Hz in F-15 (not having F-15 experience the last
figure is taken from someone else's words). A delay of the order of 0.1 sec
is HUGE by even a modest computer network standard. I don't remember by heart
the 1553 standard but I'm sure 0.1 sec delay is well within limits.

BTW, one of the replys was dealing with 1553 throughput in B-2. Please note
that throughput and delay are not the same and quite often they're
contradictory desigh trends: a design optimized for min. delay will have
lower throughput and vise virsa (assuming same cost). So, measuring a
throughput from one network point to another is irrelevant to FLCS tolerable
delay. What should be measured is the worst case max. delay, usually at top
throughput and in some particular "pathologic" case of network traffic.



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"Harry Andreas" wrote in message
...
In article , "Simon Robbins"
wrote:

"David Harper" wrote in message
om...
Does the C-130 have two 1553 buses onboard? One for flight control
and one for EW/mission systems?

I don't think 1553 is used for flight control since the latency and
speed
isn't sufficient. Mission systems may well use it though. I think by
nature
1553 is dual-redundant so that's where you might get the idea of two
from.
Not familiar with the C-130 personally though.

1553 has no inherent connection with dual-redundancy.
In fact, 1553 is usually used as a single bus.

The 1553B bus is, by definition, dual redundant. Each
bus has an A and B side. Data is transmitted on one
or the other - never both at the same time.

Tony S.