Change 1955-1958

1955 North American Aviation Downey CA Research Engineer Navaho Program

“Bomb Shelter” High Temp test facility typical control room facility layout.

There were four oven test cells equipped with special items as Vacuum chamber Variable speed pump drive.

Remote controlled TV replaced with movable mirror. Oxygen analyzer used to set oven CO2 atmosphere

Remote 3 phase motor control, remote hydraulic control, war surplus gun camera motors used for TV and mirror X-Y motion control, shake table from adjacent facility. Home made capacitor of tubes in tubes inside pressurized tank of hot oil read oil level via wheatstone bridge with full wave rectification. Intercom was connected to (illegal) home made radio. Innovation was a daily requirement.

When I hired, in the above facility was a concrete slab pending arrival of WW Bomb shelter from the Douglas Plant down the street. The bomb shelter served as a control center for hazardous testing in four ovens housed in test cells added to one side. Visitors from other aerospace firms were frequent guests. The facility was used to remotely control and monitoring performance of electrically commanded hydraulics flight controls for use on a mach 3.5 intercontinental missile. This was replaced with solid propellant missiles from silos.

The X-10 missile then flying was a test bed for an NAA Inertial Navigation System

It took off and landed using inertial navigation only

Vacuum Tubes in use and 1955 X-10 Electronics Modules with Peanut vacuum tubes

XM64 booster used first US rocket engine to launch Ram Jet powered Intercontinental mach 3 missile

We used a vacuum chamber to test hydraulic servos in simulated wing at 450 deg F. A speed brake actuator was soaked at 1100 deg F before expected to operate. Booster fiberglass control vanes were tested in rocket exhaust at Rocketdyne Canoga Park CA. Heaters in the vacuum chamber were controlled automatically using Saturable Reactors

Heat exchangers were required to provided oil at 3000 psi 400 deg F . It was necessary to design and build Oil to Oil and Electric to Oil stainless steel exchangers as no such equipment was available. Rocketdyne engineers directed me to Specialist doing boron-nickel-chrome furnace braze to blind weld tubing. Design calculations were done with slide rule. 440 V 3 phase power was controlled by a sensor. We built such a system for Johns Hopkins University doing work for the Navy.

1956 Position Transducer was Invented by Gary Collins, radar guy who played cards with hydraulics guys who had problem with wiper resisters fretting during vibration. This design is Now standard on all aircraft & missiles. Such AC position feed back required full wave demodulator (switched rectifier) for conversion to DC for servo loop control

Five were built four failed, the last was a success but blown up by range officer thinking it was not turning away from Cuba – telemetry revealed it was turning – just not readily detectable from afar.

1956 Home Made Radio. Capacitor, coil, diode only could pull in Mount Wilson signals to earphone

1956 Home Made Radio with PNP-NPN speaker driver added. Played music from Mt Wilson CA in home garage for many years

1957 Home Made transistor superhetrodyne; purchased coils were miss labeled set aside for year, coil cover removed and reconnected per real wiring – then it worked !

1960 Japanese commercial transistor superhetrodyne radio

1956 Knight Kits, AM-FM Tuner & Wireless Broadcaster

1957 Test equipment kits Oscilloscope, Signal Generator, Capacitor set, Resistor set

1958 (a) Home made test equipment: Voltmeter, Ammeter, Vacuum Tube Voltmeter & Variac. (b) Diagram of voltage control with semiconductors only. (C) Transistor Tester

1957 All Transistor Stereo Amplifier with input for FM Tuner, Phonograph & Tape deck with dual channel preamps with volume, base, treble control plus output power drivers. Bob Kelley early ham operator educated me on how to do this with out need for large output transformers. It worked very well for years.

Above test equipment was used to fine tune transistor amplifier bias. Transistor base bias must be properly adjusted to deliver HiFi to the speakers. I spent hours setting resistor values on each amplification stage – with Oscilloscope you could see, hifi signals – it was a thrill when all that mess delivered beautiful sound.

1956 G-26 Navaho high temp servo valve, by Cadillac Gage of Costa Mesa CA

1957 B-70 Bomber (in Dayton Ohio Museum)

We did extensive testing of flex hoses for it’s 4000 psi system

Lee Atwood then NAA CEO, formally Chief Engineer, unexpectedly showed up asking for a tour of our facility. Unknown to me, he was making a decision on a US Supersonic Transport. The US decided No and the Europeans decided Yes. During our one-on-one tour he asked and I told of technical upper limits we were encountering. The B-70 was replaced by the Minuteman missile and Hound dog carried on a B-52. An intended supersonic B-70 was never built.

1959 Hound Dog with Autonetics Navaho Inertial Navigator

The Hound Dog was quite successful except for when the chase plane lost track of Hound Dog released for flight over FL test range. He saw it enter but not emerge from clouds right after launch. Later the AF received a call from a farmer in Pennsylvania asking if they’d lost a missile, one had just landed in his corn field. The “hemisphere switch” had been set wrong, instead of going south it went north.

1955 Sylvania Selenium Rectifiers replaced rectifier tubes. They in turn were replaced with semiconductor Diodes. These diodes made it possible to replace automotive Generators with Alternators -- three semiconductor diodes readily converting AC to DC.

1955-1965 Simulation Lab Operational amplifier module and Beckman variable resistor. Prior to MM III analog computers were used to simulate flight conditions. Operators setting them up in accordance with “La Place Transforms” to cause simulator signals to emulate dynamic vehicle condition.

Basics worth knowing

Vacuum Tube: A vacuum tube has a heater element that heats the cathode, boiling off electrons into the empty glass tube. The plate is connected to a high DC “plus” voltage to attract electrons from the low DC “minus” voltage cathode. There is a grid element between the cathode and plate element. A signal voltage applied to the grid will attract or reject the flow of electrons from the cathode to the plate. The grid must be biased, to mid signal level, so that signal swings are not cut off. The British call them Valves.

Transistors are semi conductors with three parts, a collector, base and emitter. The three parts can be of PNP or NPN material. P kind is silicon seasoned atoms with extra electrons and N kind is seasoned with atoms with empty places for electrons, sometimes referred to as holes. PNP kind are shown with an arrow pointing away from the junction and NPN with arrow pointing to the junction. DC power is applied according to the arrow, flow from collector to emitter for PNP and from emitter to collector for NPN. The transistor serves as a flow valve. In the PNP above the transistor is turned on by supplying current to the base and turned off by blocking or draining current from the base. Current to the base (sourceing) will turn the transistor on, current taken from the base (sinking) will turn the transistor off. A small variable signal to the base can control a large signal through the transistor – a transistor can be a signal amplifier, however the base must be bias to mid signal level to prevent clipping off signal swings.

Transistors can operate in analog mode and will heat because the transistor throttles flow serving as a variable resistor; a heat sink is required to carry away generated heat. In pure digital mode it will not heat, the transistor full on or full off, no flow generates no heat and if full on there is nil resistance and nil heat.

MOS FET Transistors These Metal Oxide Silicon Field Effect Transistors have three parts: source, gate and drain. They also come in either P or N kinds. These operate on a Field effect where a field on the gate will enable or disable flow through the device, a plus or minus field turns the transistor on or off depending on if it is a P or N kind. Current does not flow from the gate, the charge on the gate controls flow.

CMOS This Complementary MOS device connects a P kind with an N kind such that a signal on the gate will turn one off and the other on, thus they are called complementary. These devices made digital microprocessors possible. The output is either full on or full off, there is no power drain, except for the brief instance when they change state. Desk top computers are equipped with CMOS memory chips to hold set up information – a small battery sustains their state while main power is off.

Transmission Gate By connecting a P and N transistor in parallel, with one side commanded by the inverse of the other, flow can pass or block AC signals.. These, used in conjunction with CMOS, enable the selection of multiple devices connected in parallel by enabling or inhibiting devices in parallel. They permit “tri state” logic: On, Off or Open.

Potentiometers This is a resistor with one end connected to plus the other to minus and a wiper that can read a selected location. These are used to measure the position of a device that moves the wiper. This was the primary kind of position measuring device during WW II. They could not be used on missiles undergoing severe vibration as the wiper would lose contact.

Variable Resistor Similar to a potentiometer except that the amount of resistance is determined by the wiper, which can go from low to high resistance. Volume controls on radio and TV work on this principle. Transistors can be used as variable resistors.

Crafts week end experiments

Coffee table made from tree and bush clippings from yard in CA

CA Home 1956

Card Table – built from center out with 3/8 x 1 x 3 inch blocks of 9 kinds of wood.

An escape from engineering

Darrell Monica Mary Julia Darrell Monica

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