The Boeing Model 299 – The First Flying Fortress

The Model 299 was Boeing’s entry into a USAAC design competition to replace the Martin B-10 as the Air Corps’ primary bomber.  Built at Boeing’s expense, the design was unusual for mounting four Pratt & Whitney R-1690 Hornet radial engines instead of the more expected two.  The design also mounted five .30 caliber machine guns in fully enclosed positions which led to reporter Richard Williams of the Seattle Daily Times calling the aircraft a “Flying Fortress”, a name which Boeing was quick to adopt.

The prototype was given the registration number X 13372 and USAAC markings for the competition.  The streamlined design was fast for its time, averaging 233 mph on the delivery flight from Seattle to Wright Field.  It was superior in every respect except for price – the Boeing design cost approximately twice as much as its competitors.

The nose of the Model 299 contained a separate fairing for the bomb sight.  On later production models this would be incorporated into the nose glazing.

The nose featured a single .30 caliber machine gun in a swivel mount which gave the gun a wide field of fire.  The design and workmanship of the gun positions was innovative for the time, as contemporary service aircraft were generally equipped with open positions which exposed the gunners to the slipstream.

A view inside the nose looking forward, clearly showing the step and opening for the bomb sight which is not yet fitted.  The Model 299 did not carry acoustical insulation in the nose, the interior was left in unpainted aluminum.

The cockpit layout of the Model 299 set the basic configuration for the more than 12,700 Fortresses to follow.  Pilot and co-pilot sat side-by-side with the throttles and propeller controls mounted in the center console where they were accessible to both.

The bomb bay should also look familiar to all Flying Fortress fans.  The Model 299 could carry up to 4,800 pounds of bombs internally.  Even at this initial design stage guide ropes were installed to help keep crew members on the catwalk.

The radio operator’s position featured insulative batting to reduce the noise in the compartment, in stark contrast to the natural aluminum finish on the rest of the aircraft’s interior.

A Boeing engineer demonstrates one of the .30 caliber waist gun mounts.  The hinged ring assembly allowed the gun to move in train, while the Plexiglas bubble fairing allowed movement in elevation.  In combination the design allowed the gunner a wide field of fire while remaining protected from the slipstream.

The exterior contours of the gun positions were very aerodynamic.  The construction and finish of the prototype was exceptional.

On 30OCT35 the Model 299 crashed at Wright Field with two fatalities, the cause was traced to a gust lock which was designed to keep the control surfaces from moving on the ground which the pilots neglected to disengage.  With Boeing’s entry unable to complete the competition, the USAAC awarded a construction contract to Douglas for 133 B-18s.  Boeing could have been financially devastated, but fortunately managed to secure a contract for thirteen YB-17s thus saving both the company and the Flying Fortress.  The Model 299 was later retroactively called the XB-17.