He yanked a board from a vegetable crate and fashioned it into a propeller. He stuck the blade onto the end of a plank and held it aloft. "It caught the wind," he says. "It just caught the wind." Soon every boy in the camp was catching the wind too. "It was my first invention," says Kuebler.
In 1942 the three Kueblers were exchanged for Allied POWs held in Turkey, and then transferred to Uberlingen, where they had some distant relatives. When the war ended, poverty and famine descended on southern Germany. Siegfried became a farmhand. The daily slice of corn bread he got with his ration card was almost inedible: It was full of stones. "Nothing means more than freedom," he says. "But freedom means nothing if you have no money."
Scattered throughout Kuebler's home are dozens of tiny black wooden cats wearing collars of fine red thread. They peer down from the tops of bookcases and cabinets—carved figures of infinite delicacy, forever ready to pounce. Kuebler made each one by hand, 10,000 in all, in the years immediately following the war. His cats sold for one reichsmark—a pack of black-market cigarettes cost 200 reichsmarks, a pound of butter, 500. "The only thing we could afford was salt," he says. Friedrich, by then 64, returned from Australia in 1948, rejoining his family after nine years of separation. The Marshall Plan was enacted and currency revalued.
A gifted student, Siegfried eventually matriculated at the Institute of Technology in Constance, Germany, where he earned a degree in mechanical engineering. He wanted a job in the aerospace industry but couldn't find one, so he joined the refrigeration department of a Swiss engineering company. Then, in 1957, he accepted a job with the Canadian Ice Machine Company in Toronto.
Kuebler returned to West Germany in 1960. He worked at a plumbing firm in Singen, designing cooling towers for big buildings. He moonlighted as an engineer on guidance systems for Sidewinder air-to-air missiles. "I finally asked myself why I was making missiles, which are no good for anyone," he says. He quit his Sidewinder sideline and went back to cooling towers, which has been his principal business ever since. Today he is an independent designer of cooling-tower parts.
Kuebler didn't turn his engineering skills to tennis until 1972, when he saw a Head Master aluminum racket and decided to reinvent it. His first attempt, the Mark 77, had interchangeable handles of three sizes and bands that could be inserted in a groove around the head to change the weight. A few years later he came out with the Plus 40, a racket that spent more time in the courts than on them. Prince's German distributor sued Kuebler, charging that the Plus 40 infringed on Howard Head's patented oversized head. Kuebler countered by rounding up old rackets in a search for what patent people call prior art. A civil court in Munich ruled for Kuebler. It turned out that Prince's patent didn't extend to West Germany.
The legacy of Kuebler's litigation is perhaps the greatest racket collection in the world. Rackets of assorted shapes, sizes and colors crowd the walls of his home and dangle from the ceilings. Kuebler has more than 1,200 frames, the oldest of which dates from 1859. He has Bourras, Bancrofts, Bryans, Berninas and G.G. Busseys; Slazenger Demons, Dohertys and E.G.M.'s; frames shaped like pears, teardrops, snowshoes; a 1903 Birmingham aluminum with steel strings and a Kuebler-designed 1976 Rassel with lead pellets rattling around inside; a bent-handled Erge, a lopsided Snauwaert Ergoneum, a disposable Myrac, an Aequale with rollers in its head and a court-tennis racket Kuebler made by following the instructions he found in a 1780 manual.
The widebody came out of a heart operation Kuebler never had. In 1984, the night before he was to undergo surgery, he sneaked out of the hospital, returned home for a few days and then flew to the Canary Islands. He holed up in a bungalow with a broad-nibbed pen and a sheaf of white paper. "It had to be white paper," he says. Emphatically. "White parchment paper. And it had to be a Chinese pen with black ink. The pen sounded scratchy on the paper, but for some reason, ink flowed."
The result of all this flowing was Und Dann? (And Then?), a Faustian fantasy about a tennis bum who's seduced by a lost tribe of Amazonian women, absorbs hallucinogens through a hole in his skull and develops an unreturnable serve with the help of his coach, the inscrutable Dr. Helmholz. The bum, Peter Grant, wins the Grand Slam, but at a price: anomie. In the most prophetic passage, Grant struggles with the accuracy of his reverse serve. "The reverse is a serve hit with your back to the net," says Kuebler. The idea came from an obscure reference in a 1920 instructional book by Bill Tilden.
Dr. Helmholz solved Grant's problems with service accuracy by creating a monster, in the form of the resonance racket. "When I wrote this," says Kuebler, "I didn't even think of making such a racket. Then later I was sitting in my office and I said to myself, Well, this is a very interesting idea. Why don't you take all of your brains together and start to calculate?"