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Thursday, June 27, 2013

Onward to Kitty Hawk - part 2 of "First to what?"

So far, the quest to fly had been Wilbur Wright's alone.  in the summer of 1900, he engaged some of the rest of his family - Orville, with whom Wilbur designed and built the 1900 glider, and Katharine, who helped sow the fabric for the wing covers.  Katharine doesn't get as much credit as she should, because she didn't go to Kitty Hawk and attend the test flights. And test flying is what they did at Kitty Hawk, for the next 4 autumns.

The Wright's bicycle shop was their source of income - the Wright's built their bicycles in the winter and spring months, so that they had stock to sell in the Ohio summer.  Once the shop was stocked they could use their workshop for other things, such as airplane design.  Once the summer bicycling season was done, they could spend a few months getting away - and flying.

In the Autumn of 1900, Wilbur traveled to for the first time to Kitty Hawk with his glider - their research had suggested that the autumn winds were favorable for test flying there.  Orville followed after Wilbur had set up camp, and Orville had closed the shop.  They initially flew their glider as kite to test out its lifting and wing warping controls.  Due to unavailability of 18 ft lengths of spruce in the area, Wilbur instead used 16 ft length of white pine to make the wing spars, substantially reducing the wing area.

The 1900 glider flying as a kite

The glider flew well despite the shorter wings, and Wilbur began free glides down the sand dunes, mostly short and low to the ground.  They were concerned about avoiding the not-well understood stall phenomenon that had killed Lilienthal, and had determined to control their risk by flying low and using a "canard" design with the fixed elevator  in front.  Pitch control was by weight shifting, but roll was controlled by wing warping.  The Wrights were encouraged by their beginning, and Orville began to become as invested as Wilbur in their project.

The Wrights were wise to fly low - several times the gliders's main wings did stall, but with the canard elevator, instead of a fatal pitch down, the glider just settled to the ground in a flat attitude, leaving both man and structure intact and undamaged.  The wing warping system worked well, and Wilbur was able to make controlled turns - an aviation first.

Feeling that they were making good progress, in the spring of 1901 Orville and Wilbur began designing a new glider - bigger, and with a moveable elevator - the biggest aircraft yet flown and built to their design using all the best data available from Octave Chanute.

The larger, but disappointing 1901 glider

Dan Tate and Orville Wright launch Wilbur in the 1901 glider
The 1901 glider was a disappointment.  The Wrights had used Lilienthal's lift tables and Chanute's suggestion of a 12:1 wing camber instead of the 22:1 camber of their 1900 glider (the camber is the ratio of the wings length from front to back, divided by the height of the wings maximum curvature at its thickest point).  The resulting lift didn't match what the tables said it should - it only generated about 1/3 of their calculated value, and was substantially more draggy, having to fly at an exaggerated pitch up (angle of attack) to generate enough lift to carry a man.  The pitch control was erratic and not fast enough.  They experimented with a smaller control surface, but the problems remained.  Still Wilbur (who did all the flying) was able to get some long glides and built up his level of flying experience - and suffered some serious stalls, fortunately all at low level and slow speed, and the damage to pilot and machine much reduced thanks to their "backwards" design.  The picture above shows Wilbur flying the glider, with Orville and Dan Tate holding the wings.  You can clearly see the greater wing curvature and the moveable forward mounted elevator.  You can also see the open area below Wilbur - allowing him to supplement the elevator pitch control with weight shifting.

The 1901 glider continued to show the value of wing warping, able to make controlled, banked turns most of the time, but showing an odd tendency to sometimes turn the opposite way - pivoting around the raised wingtip. The Wright's left North Carolina discouraged, Wilbur commenting to Orville that men would not fly for fifty years.

1 comment:

Karlene Petitt said...

Could you imagine being on the brink of the aviation industry. Wish they could see what they had started, had turned into.