First Generation SAM fin actuators

[BernardQuatermass21]

I know this is a bit niche, but it seems that one of the challenges for the developers of the first SAMs was to source control surface servos that were small, light yet powerful and fast enough to do the job.

Does anyone here have technical details or pictures of the servo actuators used for those early birds ? Nike Ajax, Talos, Berkut, Thunderbird, Bloodhound, Sea Slug etc.

 

[Hamez_boi]

do you know if they were electric or hydraulic? iirc some used bleed off of the SRB to actuate with electric control

 

[Sferrin]

Talos Missile Aerodynamics and Control History

"The Talos wings were rotated in response to guidance system commands. The rate of rotation affected how quickly the wings could produce force in a desired direction, and this determined how quickly the missile could respond to control system commands. The rate of wing rotation was 170° per second. The system adjusted control response for speeds ranging from low subsonic during boost phase to more than Mach 2 during the beamriding cruise phase. It compensated for altitude from sea level to 70,000 feet. The control system also corrected for the change of center of gravity as fuel was consumed.2

The servos that turned the wings were hydraulic, drawing their power from an air turbine pump. Pressurized air from inside the ramjet diffuser passed through the turbine and was then vented outside to the low pressure atmosphere. A high pressure nitrogen reservoir provided power to drive the turbine for the few seconds of boosted flight when airflow through the missile was reduced. About 25 horsepower was required to drive the wing servos.2

Space for control mechanisms was limited by the large diffuser duct running down the center of the missile. The servo mechanisms had to be relatively small and therefore of limited power. Wing designs were studied to find one that allowed the smallest movements necessary to deflect the wings during maneuvering through the expected range of speeds. The wings were designed so the center of pressure on the wing surface changed little with changes of speed and with wing rotations. This allowed the axis of rotation to be chosen to minimize wing rotation, and this simplified the control system. The final wing design was known as the Bumblebee planform.1"
Nike Hercules

Hercules Functional Description

Nike Hercules Missile Functional Description: Aerodynamics, guidance, hydraulics, propulsion, warheading.

nikemissile.org

"Hydraulic System

The hydraulic system consists of three actuator assemblies, a mechanical linkage, and an accessory power supply or hydraulic pumping unit. The actuator assemblies are electrically controlled by the steering orders from the missile guidance set and, by means of the mechanical linkage, produce the appropriate deflections of the elevons to maneuver the missile.


Hydraulic power to the actuator assemblies is supplied by an accessory power supply (APS) in some models and by a hydraulic pumping unit (HPU) in other models. The APS uses and ethylene oxide decomposition reaction turbine to drive a hydraulic pump. The HPU uses a squib-activated battery to power a dc motor which drives a hydraulic pump."

 

[dannydale]

Wing designs were studied to find one that allowed the smallest movements necessary to deflect the wings during maneuvering through the expected range of speeds. The wings were designed so the center of pressure on the wing surface changed little with changes of speed and with wing rotations. This allowed the axis of rotation to be chosen to minimize wing rotation, and this simplified the control system. The final wing design was known as the Bumblebee planform.1

As an aside I've always been fascinated by design processes that result in unique and iconic shapes as a byproduct.

 

[NMaude]

Flight and Aircraft Engineer (As Flight International was called back in the 1950s) had several very, VERY detailed technical articles to do with missiles including how they were controlled, the UK conducted large-scale missile tests in the late 1940s and throughout the 1950s with most of these test-trials being conducted at the Woomera test-range in Australia, they launched quite a few CTV (Control Test Vehicle) test-flights for example.​

 

[Dilandu]

I know this is a bit niche, but it seems that one of the challenges for the developers of the first SAMs was to source control surface servos that were small, light yet powerful and fast enough to do the job.

Does anyone here have technical details or pictures of the servo actuators used for those early birds ? Nike Ajax, Talos, Berkut, Thunderbird, Bloodhound, Sea Slug etc.

IRRC, most of them used hydraulic servomotors or servopositioners, with pressure of working liquid provided by gas generator (same gas generator usually powered the missile's dynamo). The hydraulic system was essentially the only availble solution then, that was both fast-reacting and precise enough to work.

 

[NMaude]

The Sidewinder used an open-loop hot-gas* actuator system where the control-servos were a 'Torque balance" type where the steering signals commanded torque not degrees of deflection. Basically the canards kept deflecting until the externally induced torque (Created by aerodynamic forces acting on the canards) cancelled out the commanded amount of torque.

*That hot-gas was used to drive a electrical generator (By a simple impulse-turbine) that powered the seeker electronics.