Oba St. Clair



• In 1937 created the first Control Line model.

• Developed first a single line version and worked up to four Control Lines.

• Testified in a lawsuit brought by Jim Walker, bringing down Jim’s claim of the invention of Control Line flying.

• Able to do a flat spin with his Control Line model.

• Created a twin-cylinder engine by using two Forsters geared together and auto oil pump gears to increase the power of his model.

That winter, Oba built 18-inch span rubber-powered airplane from cardboard, for himself and all the neighbor children. He still recalls blowing the dry snow off the airplanes and the many enjoyable flights. Oba's family moved to Yamhill, Oregon, in 1932 and he discovered that the hobby of model airplane building existed in the rest of the world.

He bought his first strands of model airplane rubber in Greshan, Oregon. That was a thrill he recalls with a broad smile on his face. The performance of his model was improved by the new rubber and the development of a pendulum control of his own design.

Oba was 17, working in his father's mill, making 20 cents an hour. He had to travel 20 miles to the mill, so he bought a two-cylinder motorcycle, a Harley Davidson, with a sidecar. He could haul his tools in it and save a lot of gas money with which to buy more model airplane supplies.

In the winter of 1933, he learned about soldering and built a replica of his motorcycle without the sidecar. Its power was a clock spring equipped with a governor. You could set it to run in a left or right hand circle or straight ahead. The model looks great today, super detail with working shocks on the front wheel and seat. The rubber tires were from ashtrays.

Oba says the motorcycle model was “the thing that started it all.” He was demonstrating the motorcycle at the sawmill, when one of his father's employees asked him why he didn't build a large motorcycle with a gasoline engine. Oba had wished many times for a small motor for his airplanes, but didn't believe they existed. His friend told him they did indeed make such an engine, and he would bring him a magazine to prove it.

He brought Oba two copies of ModernMechanics and Invention magazine, one dated August 1935. The magazine had an advertisement on page 91 showing a little Brown, Jr., 6-1/2 oz. engine. Oba says, “That really turned me on.” (Oba still has the magazines.) The magazine also featured a construction article for the Berliner/Joyce Fighter (reprinted in February 1977 issue of Model Builder magazine). Oba started construction while saving for an engine.

The Great Depression was still keeping money tight. Oba made a trip to McMinnville and checked all the newsstands for magazines and found his first model magazine, Model Airplane News. It was the first model magazine he had ever seen. It was a thrill he will never forget. The Brown, Jr. and Forster were advertised with 1/5 and 1/3 hp respectively.

He decided he wanted a twin-engine motor due to his Harley experience. He planned to couple two engines together to make a twin. Bear in mind at this point he had never seen more than a photograph of an engine. Oba chose the Forster Model A because it was advertised as more powerful. He knew he couldn't buy two engines to make a twin for a long time, so he would have to settle for a single cylinder temporarily. He saved $12 for the engine and $3 for the condenser. Delivery took six weeks; the factory sent Oba a postcard every few weeks telling him to be patient and that the engine was coming.

When Oba got his engine, no props were available, but the engine instructions recommended a 16 inch diameter prop, but didn't mention pitch. Oba carved an ash prop to 6-inch pitch, which later proved to be a good selection. Construction of Oba’s Berliner/Joyce Fighter was well along, ready for covering with engine mounted, when, Oba says, “I was not going to...Oh, look at that picture where it's skinnied down. No way can I turn that little fragile airplane loose on its own and even hope to have it come down in one piece. No way! I cannot do that and I didn't!”

There were no fields around where Oba could fly that were larger than a quarter mile diameter and they were full of ditches and hedgerows. He couldn't take the chance. He said, “My dream would be destroyed.” Had Oba had a flying field, he would have flown Free Flight and Control Line might have come much later.

Oba reasoned that if he could fly in a circle the wing would always point to the same spot on the ground. If he mounted a fishing line on the left side and set the airplane controls to turn right, he could fly in a circle. He also reasoned that if he had low power it would do some ground hopping. This he thought could be very dangerous, so he designed an engine shut-off that he refers to as “no ground hopping” that worked when he touched down.

Next, he thought that if the nose of the airplane started to turn in to the center of the circle or away from the center, the distance from the pilot to the center of the airplane would get smaller, due to the wing pushing the line in a bend. This, he reasoned, would make a long wing safer to fly than a short wing.

His airplane was already built, so he added a long spar to the inboard wing to work as a long wing. His reasoning now told him that all the drag was on the inside so he put a spar on the outside wing to equalize the inside guide spar, then put an airsock on the end of the spar to compensate for the drag of the fishing line. He used a fishing pole to keep the lines tight.

The first flight was made in June 1936, and was a total success. The engine would slow down when it was low on fuel and slowly descend until the “no ground hopping” shutoff would take over and cut the engine for a perfect landing. Oba was delighted.

Experimentation soon began by shortening the inboard spars that acted as a fishing line connector and the outboard spar that held the windsock. The process continued until they were shortened to within the dimensions of the wingspan.

Everything was working well, but Oba says he was really busy moving his fishing pole around on days that were windy. He mentioned his airplane had a tendency to climb into the wind and descend down wind. He figured that if he had two lines he could change the trim in flight. Then he thought, “Why trim? Why not just operate the elevators as on the real aircraft?” And so, BINGO! That was the way to go.

It was June 1936 and Oba was going to change the Berliner/Joyce Fighter biplane to two lines, but his wife was expecting a child soon. He didn't have time to make the conversion before, so he decided to fly it as it was since he was having so much fun and he would wait to build a new plane that coming winter.

Information about Oba St. Clair is taken from two articles that appeared in Model Builder magazine’s November and December 1981 issues. The articles were written by Charles Mackey and Dale Kirn. Charles Mackey submitted the information to the AMA History Program.