Popular Electronics September 1964, V21 N3 Previous Index Next
ON a warm September afternoon Carl and Jerry were helping Bill Vardon tie down his Cessna plane at the small municipal airport. Bill, a schoolmate at Parvoo University, had just flown in from Texas to spend a few days with his two friends before going on to the World's Fair in New York. As they finished the job, Police Chief Morton and a stranger came toward them from the airport parking lot.
"Your folks said I'd find you here," the chief greeted Carl and Jerry. "I'd like you to meet Mr. Ringle, an insurance company investigator."
When Carl introduced Bill, the chief shook his hand, and said: "I don't want to interfere with your visit, but I always turn to Carl and Jerry when I'm stumped. In the past they've come up with some pretty outlandish electronic gadgets to solve my problems, and I'm hoping they can do the same for Mr. Ringle. Do you mind if we tell them about his problem?"
"Gosh no!" Bill replied. "The Wireless Boys here also have a pretty wild reputation at old Parvoo in the problem-solving department, and nothing would please me more than to see them at work."
"Good," Mr. Ringle said as all four squatted down in the shade of a wing. "I'll try to be as brief as possible. I have reason to believe that a family named Monk may have victimized insurance companies three times in the past and are getting ready to try it a fourth time right here in your town. This is the way they work their racket: A member of the family, who is heavily insured against injury while riding in an automobile, is involved in a one-car crash with no witnesses. In addition to some small scratches, the insured claims to have an injured back, a nerve irritation, or some other injury that is practically impossible to prove or disprove medically.
"Mr. Monk had two such 'accidents' and collected substantial sums both times. No company would insure him after that, but then his wife met with a similar accident and collected. Since that time I've had those two and their grown son under constant surveillance, and I followed them here from out west. They're staying at a motel near town, and every day they go for long drives along back roads. They have a CB radio in their car, and the son has a hand-held transceiver. Sometimes they drop him off and drive around talking back to him from the car. We've monitored the conversations and they're innocent enough, but we think they're looking for a place to have another accident. They're probably testing the radio so they can give the son warning if the cops show up while he's faking his little catastrophe."
"The boy is covered by a large insurance policy, and yesterday he bought a used car," Chief Morton interrupted. "Since he already has a new sports car back home, that looks mighty suspicious. At our request, the car dealer is stalling on delivery for a couple of days to give us time to work out some plan." "If the Monks stick to the MO that has worked so well for them in the past," Mr. Ringle continued, "this is probably what will happen: Late at night the boy will drive to a selected spot on a lonely road that parallels a ravine, canyon, quarry, or similar dropoff. He'll get out of the car, block the accelerator down, and jerk the shift lever into Drive. The car will hurtle over the edge of the bluff and be smashed down below. The boy will then work his way down to the car, remove the accelerator block, examine the damage, and make up a story to fit -the steering mechanism failed, or the head- lamps went out, or the brakes locked. The damage will be such that his story can't be disproved. Finally, he'll tear and soil his clothing, inflict some small scratches on his body, then climb back to the road and wait to be discovered 'nearly unconscious.' His parents will have been watching from a strategic point to guard against anyone's discovering the wreck before it's ready to be discovered."
"We can't risk trying to keep a constant tail on the boy -not with his parents guarding his trail," the chief said. "What we need is something that will give an alarm the instant he wrecks the car and keep on signaling its location. Then, with a little luck, we should be able to reach the spot before the boy has finished setting the scene. Any ideas?"
Carl and Jerry registered deep thought, but no inspiration came.
"I may have an idea," Bill offered. "Last fall the Federal Aviation Agency conducted tests in California and Utah to determine the feasibility of crash-locator beacons for civil aircraft. I was interested, and George Moore, Director of Flights Standards Service, and James Rudolph, Chief of Operations Division of FSS, sent me reports on the tests. "The beacons tested were rugged, low-power transmitters designed to break loose from a plane during a crash or to be released by the pilot just before a crash. The transmitter turned on automatically at separation. It was decided that the transmitter should be crystal-controlled on 121.5 mc., a frequency received by all FAA search equipment, and that it should put out a minimum of a quarter of a watt and be seventy to ninety per cent modulated by an audio note sweeping between 2000 and 2300 cycles two or three times a second."
"How far can a search plane hear such a signal?" Jerry asked.
"It depends on the altitude and heading of the plane. When flying away from the beacon, the pilot could hear the signal thirty miles at 1000 feet, fifty miles at 5000 feet, and sixty-five miles at 10,000 feet. Because of the directional characteristics of the plane's Posifix antenna mounting, these ranges were all cut thirty-three to forty per cent when the plane was flying toward the beacon. More important, though, the pilot quickly located the beacon in all cases and was able to fly within 300 feet of a vertical line straight above it." "That's it!" Jerry exclaimed, jumping to his feet and bumping his head on the plane wing in the process. "We build a ten-meter transistorized transmitter -transistors can take the shock- in a steel case and fasten it to the bottom of the car with a spring-loaded clamp. A crash will throw the transmitter free and start it sending. We install a transistorized ten-meter receiver and direction-finding loop antenna that we use for hidden transmitter hunts in Bill's plane. You fellows alert us when you think the Monks may stage their accident, and we take to the air. As soon as the wreck occurs, we pick up the signal and quickly track it to its source. The location is relayed to you on the plane's radio, and you rush out and try to catch young Monk flagrante delicto. How's that?"
"very good, including your legal Latin," Mr. Ringle replied. "It sounds just wacky enough to work. But how long will it take you to build the transmitter?"
"We'll be ready to install it on the car tomorrow morning and can check it out in a couple of hours," Jerry promised.
"Good enough!" Mr. Ringle said enthusiastically. "See you tomorrow."
BILL FOUND a steel case shaped like half an egg-shell in a junk yard, and they poured lead in the bottom so that it would always return to an upright position after being moved, like a humpty-dumpty toy.
Jerry "lifted" the transistorized transmitter circuit bodily from a CB l-watt transceiver. The modulator was driven by an audio oscillator, and the collector of this oscillator and the collector of a blocking oscillator were fed through a common resistor. Any change in the audio oscillator collector voltage produced by the varying current demands of the collector of the blocking oscillator produced enough frequency change to make the signal easily identifiable.
Carl's contribution was a self-erecting antenna. A compact telescoping antenna was base-loaded to resonance when fully extended some 50 inches. He installed a CO2 cartridge from a BB pistol inside the case and arranged for the gas to be released inside the sealed hollow tubing of the collapsed antenna shortly before the transmitter was turned on by a delayed-action switch. This caused the antenna to shoot up to its full length through a foil-covered hole in the top of the case. The first time they tested it, too much pressure tore the antenna in two and buried the tip of it in the ceiling of the basement laboratory, but a safety valve cured that.
The case was mounted on its side in a spring-loaded holder designed to boJt to the bottom of the car body. The spring tension was adjusted so that it would hold the case firmly in place during ordinary road shocks transmitted through the car's suspension system and yet release it if the body of the car received a heavy jar.
It was after midnight when the trio finished their work, but they were at the police garage at seven the next morning to install their brainchild on the used car. This did not take long, and they were soon on their way to the airport to install the direction-finding equipment in Bill's plane. To test it, they removed the beacon transmitter from its case under the used car and brought it along.
The small shielded loop was mounted on the end of an aluminum tube thrust up through a small hole in the floor of the plane. Flexible coax cable connecting the receiver to the loop permitted the latter to be turned freely on its vertical axis and to be rocked through a considerable arc on its horizontal axis.
Then Carl drove away with the beacon transmitter to "plant" it, and a few. minutes later Bill and Jerry took off in the Cessna. When Carl turned on the transmitter, Jerry picked up the signal immediately; and in very short order the plane was circling over the spot where Carl had hidden the transmitter. Satisfied with their test, they returned to the police station and replaced the transmitter in its concealed case.
THE CAR was delivered to the Monk boy that afternoon, but nothing happened! Two days went by while the three of them chewed their fingernails. Wherever they went, arrangements were made so that Chief Morton could reach them quickly, but he never called.
On the evening of the third day they went bowling. Jerry was paged about 10:30. The chief was on the phone.
"This may be it," he said. "The young guy has just taken off in his car. Get into the air as soon as you can and keep listening for me on that portable police receiver I gave you."
Quickly the boys drove to the airport, warmed up the Cessna, and took off. It was a calm, moonlit autumn night, perfect for flying. As they circled out over the countryside, the voice of Chief Mor- ton came from the little portable police-frequency receiver: "We've tailed the boy in a big circle out north of town, but now we've got to drop him. Our stake-out at the motel says the parents have just driven away, and they're probably going to watch his trail to see if he's being followed. It's up to you fellows now. Mr. Ringle and I will be standing by at the station."
While Bill cruised over the city at about 3000 feet, Jerry, sitting in back, strained his ears and moved the loop antenna. Carl sat beside Bill with a pair of 7 x 50 binoculars in his lap. Minute after minute ticked by with nothing happening; but then, close to midnight, the little ten-meter receiver suddenly came alive with a rhythmic "wheee-wheee-wheee" sound.
"That's it!" Jerry shouted, maneuvering the loop delicately. "It's coming from either east or west. Try flying east."
Bill obeyed, but in a couple of minutes the signal was noticeably weaker. "Turn around," Jerry ordered. "It's coming from the west."
Shortly after they turned, the signal began to build in intensity, and it continued getting stronger as they flew west along the river. gradually losing altitude. Jerry actually tracked the signal's direction by keeping his loop oriented for minimum signal strength; the nulls of a loop antenna are much sharper than the lobes. In two or three minutes even this minimum signal was showing strongly on the S-meter, indicating that they were getting very close to the transmitter.
"He must have driven the car off that high limestone bluff at Cedar Rapids," Carl muttered, scanning the river bank below with his night glasses. "It's just ahead. Throttle back and fly as low as possible so I can get a good look -hey! I see the car! It's right there at the bottom of that big white bluff! If the chief and Mr. Ringle drive out the highway to that cement plant and then walk across the railroad tracks and that field, they can reach the top of the bluff without being seen by anyone parked along the river road."
Bill was already relaying this information to the airport operator who had been alerted to give it instantly to the police. At the same time Bill was coming in for a landing at the airport. The wheels of the plane had hardly stopped turning when the fellows piled out of the aircraft and ran to their car. Fortunately the airport was on the west side of town, and within minutes they were sliding to a halt beside Chief Morton's car parked at the deserted cement plant along the highway.
Hastily but silently they scrambled over the railroad embankment and ran across a pasture that separated the railroad from the river road. Very carefully they approached the top of the bluff and crawled to where the chief and Mr. Ringle were lying on their stomachs peering over the edge. A movie camera hummed quietly in Mr. Ringle's hands, recording the scene.
Straight below them, clearly seen in the bright moonlight, a young man was methodically tearing his shirt and trousers and smearing dirt into the garments. Then, while they watched and cringed, he heated the point of a large needle in the flame of his cigarette lighter and used it to inflict several scratches on his face, chest, and forearms. This done, he took a last careful look at the broken wreckage and started walking upstream.
"Let's go," Mr. Ringle whispered, shutting off his camera. "We don't need to hurry. He has to walk almost a quarter of a mile up-river before he can climb back up on the road."
"Aren't you going to wait and arrest him?" Carl demanded.
"Not now," Mr. Ringle replied. "1'11 wait until he files a claim backed up with the big lie he's preparing right this minute. Then I'll spring the pictures made on the special ultra-fast film in this camera. With your testimony to back me up, I think we'll be able to recover any of the insurance money the Monk family has left. Jerry, what were you looking for with those binoculars off to the right of the wreck?"
"For what I spotted," Jerry said with a grin. "Our little beacon was jarred loose as the car went over the edge of the cliff and is lodged against a small shrub about halfway down the slope. As soon as young Mr. Monk is 'found,' Carl and I will come back with ropes and get the transmitter before someone sees it and starts wondering about it. We don't want to start any more flying-saucer stories!" -30-
Previous Index Next