This video initiates a teardown series of a vintage Smith Air Data Computer, a complex electromechanical instrument. The initial inspection reveals its robust external features, including a 200V 3-phase power input, Pitot Static pressure ports, and an hours counter. Internally, the unit showcases sophisticated engineering, featuring two distinct force-balance pressure sensors—one for airspeed (differential pressure) and another for altitude (static pressure). The internal architecture is characterized by numerous electromechanical components, including an intricate network of cams, gears, and differentials, alongside multiple servo motors and associated analog amplifier modules. The presence of an altitude encoder for transponder use and extensive calibration potentiometers highlights its precision. The video emphasizes the complexity of reverse engineering such a device, with the speaker noting the availability of a second unit for testing purposes in future installments.
Exploring the Vintage Smith Air Data Computer: An Electromechanical Teardown
0:05 Introduction to a Vintage Air Data Computer: The video begins a series on a complex electromechanical Air Data Computer manufactured by Smith, powered by 200V, 3 phases.
0:24 External Features: The unit features an hours counter, Pitot Static input pressure ports, and multiple circular connectors.
0:32 Teardown Plan: The creator purchased two units, dedicating one for a detailed teardown and the other for functional testing.
1:04 Internal Electromechanical Design: Upon opening, the device reveals a "beautiful electromechanical" design with an incredible number of intricate gears, cams, and differentials, highlighting its complexity.
1:16 Pressure Sensors: It contains two "Charge Balance Unit" pressure sensors: one differential sensor for airspeed and another static pressure sensor for altitude, both utilizing bellows to convert pressure into force.
1:38 Force Balance Principle: These sensors operate on a force balance principle, where the force from the bellows is compensated by a spring and a motor, guided by a zero detector and pickup coil.
2:35 Electronic Modules: The unit includes five identical servo amplifier modules (each with two power transistors, suggesting five internal motors) and two other distinct electronic modules.
3:04 Robust Power Supply: A substantial internal power supply is observed, featuring tantalum capacitors, power diodes, and toroidal transformers.
5:36 Intricate Mechanical Computations: The core of the device is a dense assembly of cams, gears, and differentials, responsible for complex mechanical computations, making reverse engineering a significant challenge.
8:01 Altitude Encoder: The altitude module includes an encoder with many wires, specifically used to transmit altitude information to the aircraft's transponder.
8:12 Multiple Motors and Control: The system incorporates several AC motors (including servo motors) that drive cams and shafts, which in turn adjust potentiometers and control the sensors.
10:57 Calibration and Adjustment: Scales on gears and numerous potentiometers/trimmers indicate extensive calibration and adjustment capabilities for precise operation.