One of the monthly columns in R/C Modeler magazine, written by Chuck Cunningham, entitled "Cunningham on R/C," that reported on the current state of radio control, which had only fairly recently evolved into fully solid state, proportional control systems. Anyone involved in electronics is painfully familiar with the weird kinds of issues that crop up in complex circuits that operate in hostile environments. The March 1970 issue contained part of an article authored by D. L. Klipstein, Director of Engineering, Measurement Control Devices, entitled, "Murphy's Law: The Contributions of Edsel Murphy to the Understanding of the Behaviour of Inanimate Objects.*" Only a few of the items were printed in Cunningham's column, but I managed to locate a copy of the full article on the Archive.org website. He must have selected those which he figured were most applicable to radio control systems.
* E.E.E. Magazine (Electronic Equipment Engineering, merged with EDN), Vol. 15, No. 8, August, 1967, pp. 91,92
Edsel Murphy's Law (Cunningham on R/C excerpt"
The other day I was having a hard time obtaining a special part that I had purchased for my company. Production of a large contract had been stopped because the supplier had shipped the wrong part. All of the paper work was correct, but the guy in the shipping department had put the wrong size part in the box. The correct parts had to be air freighted in and, even so, the project was held up for four days. A friend of mine in the suppliers office mailed me an article clipped from an Electrical Engineering magazine. It was titled, "Edsel Murphy's Law Governing Inanimate Objects." Perhaps some of you have been exposed to Edsel Murphy's Law, or know what it is. Simply stated it means, "What ever can go wrong, will." Or, expressed mathematically 1 + 1 ~ 2, where the symbol ~ means "seldom ever." The article went on to point our many applications of Murphy's law as it related to electrical engineering. These seemed to be related to the sport of R/C. I've included some of Murphy's laws as shown below:
- All warranty and guarantee clauses become void upon payment of invoice.
- The necessity of making major design changes increases as the fabrication of the model approaches completion.
- Original drawings will be lost in the mail.
- Any error that can creep in, will. It will be in the direction that will do the most damage.
- Any wire cut to length will be too short. (The same goes for a piece of balsa wood.)
- Identical units tested under identical conditions will not be identical in the field.
- The availability of an item is inversely proportional to the need for that item.
- A dropped tool will land where it can do the most damage. (Also known as the law of selective gravitation.
- A device selected at random from a group having 99% reliability, will be a member of the 1% group.
- The probability of a dimension being omitted from a plan or drawing is directly proportional to its importance.
- Interchangeable parts won't.
- If a prototype functions perfectly, subsequent production units will malfunction.
- Components that must not and cannot be assembled improperly will be.
- If a circuit cannot fail, it will.
- The most delicate component will drop.
- A fail-safe circuit will destroy others.
- A transistor protected by a fast-acting fuse will protect the fuse by blowing.
- A failure will not appear until a unit has passed final inspection.
- If an obviously defective component is replaced in an instrument with an intermittent fault, the fault will reappear after the instrument is returned to service.
- After an instrument has been fully assembled, extra components will be found on the bench.
My thanks to "D. L. Klipstein" who authored this article. in the first place. If you can't find a bunch of parallel situations in our hobby, be it in construction aircraft, or repair of radio sets, then you'd better get back to work, and skip all of this reading jazz.
Good luck, and good flying. When the snow melts, that is!
Posted May 15, 2019