Model 299: Boeing’s Big Bomber Design Rose From Its Own Ashes

Boeing’s Model 299 was designed and built at the company’s expense to meet the specifications contained in a 1934 US Army Air Corps (USAAC) proposal for a multi-engine bomber to replace Martin’s B-10. The design was to be able to carry what the Air Corps referred to as a useful bomb load to an altitude of 10,000 feet for ten hours duration.  The Air Corps also specified a top speed of no less than 200 miles per hour. The USAAC wanted the aircraft to be able to operate from such far-flung places as Alaska, Hawaii, and Panama.

Boeing design engineers were led by E. Gifford Emery and Edward C. Wells. The design team drew what has been described as a cross between Boeing’s previous XB-15 four engine bomber prototype and the Model 247 commercial airliner. Armed with five .30 caliber machine guns and capable of lugging a 4,800 pound payload, the Model 299 was powered by four Pratt & Whitney R-1690 750 horsepower Hornet radial engines.

The Model 299 first flew on July 28^th 1935 under the controls of Boeing chief test pilot Leslie Tower. When the press got a look at the aircraft after the first flight it was dubbed “Flying Fortress.” The name stuck immediately- so much so that Boeing trademarked the moniker for the bomber. Boeing’s claim that the Model 299 would be able to continue its mission should the aircraft lose an engine would be put to the test countless times in the future, but let’s not get ahead of ourselves.

Pitted against the Douglas DB-1 and the Martin 146, both twin engine designs, the Model 299 flew from Seattle to Wright Field for the fly-off competition in just over nine hours at an average cruise speed of 252 miles per hour. Inevitably the Model 299 outpaced the competition at the fly-off, with the USAAC believing that the long range of the Model 299 would better suited to the Air Corp’s planned mission requirements. The USAAC liked the Model 299 so much that even before the competition was over an order for 65 Model 299 aircraft was being considered. But the 299 was expensive. The Air Corps would get what it paid for, correct?

Development of the Model 299 continued. But on October 30^th 1935, Boeing chief test pilot Leslie Tower and Army Air Corps test pilot Major Ployer Hill took the Model 299 on an evaluation flight. After takeoff the aircraft was seen to enter a steep climb and then stall, after which the aircraft nosed over and crashed killing both Tower and Hill. Two observers were injured but survived the crash. It didn’t take long to determine the cause either: The crew forgot to remove the gust locks that immobilize the empennage control surfaces (elevators and rudder) on the ground. In neutral position the locked control surfaces allowed the Model 299 to take off but not to maneuver.

Of course the smoking hole in the ground that was now the Model 299 could not complete the evaluation. But the USAAC was not about to give up on the aircraft. After all, no issues had been found with aircraft itself. The accident was caused by pilot error. Though the Model 299 was expensive compared to the twin engine designs from Douglas and Martin, it was also much more capable. That said, the USAAC went ahead and ordered the DB-1 instead of the model 299. You know the DB-1 as the Douglas B-18 Bolo (or Digby in Canadian service).

The Lasting Legacy of the Model 299

Boeing pondered the cause of the crash of the Model 299. They proposed a solution that is still in use today. In fact their solution can be found in just about every aircraft manufactured anywhere since World War II. You probably wouldn’t want to fly without one. Their solution? The checklist. Had the Model 299 pilots had one that day they would have removed the gust locks prior to takeoff. Checklists have evolved over the years since then to become the vitally important items to pilots everywhere they are today. Thanks to the Model 299. Oh, and one other thing. The Model 299 was eventually redesignated Y1B-17, then YB-17, and even XB-17. But the extraordinary aircraft that was the model 299 became the deservedly legendary B-17…the Flying Fortress. But that’s another story.