Thirteen Ways to Keep It Simple
- Use as few modes of power as the requirements permit. You can operate different parts of the same machine with ac electricity and DC electricity, both at various voltages, pneumatics of different pressures, hydraulics of different pressures and fluids, internal combustion engines, and steam. Each may be ideal for its particular load, but would the overall machine and its customer be better off if everything operated from DC electricity at a single voltage?
- Use as few modes of control as the requirements permit. You could combine digital electronics, analog electronics, analog pneumatics, relays and semiconductors, pneumatically and hydraulically operated valves, and mechanical linkages, but a single microprocessor with output amplifiers feeding electric motors and solenoids and fed by transducers with electrical signals is hard to beat these days.
- Use as few kinds of materials and components as the requirements permit.
- On control panels, group displays with corresponding controls. Separate groups of controls. Array controls to model their effects; e.g., put the up button over the down button. Follow conventions.
- Form the habit of critically examining machines, buildings, or enough to round so that they will go together. A leak check port permits injection of compressed air between the 0 rings to test for leakage. This air moves the inner 0 ring to the wrong end of its groove so that it must move back when working pressure is applied (which should do little harm), but the air which does leak past the inner 0 ring tunnels through the heat-insulating putty and establishes a path for the hot rocket gas to reach the 0 rings. This design has now been improved: it will now have three 0 rings in series! There is a single O ring in a groove of standard handbook dimensions. The groove and mating surface are on the faces of the cylinders rather than on the diameter, so machining tolerances affecting squeeze are on a Vi-in dimension rather than on a 12-ft dimension. Mechanical coupling is done with a conventional coupling-band similar to those made for many years by the Marmon Co. Leak testing is done by wrapping with a rubber band, applying vacuum from a standard mass-spectrograph helium leak detector, and releasing some helium inside the rocket chamber. Ports are provided for injecting the heat-insulating putty and sensing that it is there.
