The prototype Boeing 307, c/n 1994 NX19901, climbing out from Seattle. This photo has been claimed to show its maiden flight for which it would be lightly loaded, but it is unlikely to be the first take-off, the steep angle of climb suggesting a fly-over.

Самолёты на фотографии: Aircrafts on the photo: Boeing Boeing 307 Stratoliner - СШАUSA - 1938

The "soap test." To find leaks in the Stratoliner the seams were painted with soap solution while the body was blown up.
The pressure cabin of the Stratoliner, the first pressurised production airliner, is tested with a soap solution painted over the external seams and rivets, any leaks showing as bubbles. There is no suggestion that this was continued on production machines!

Самолёты на фотографии: Aircrafts on the photo: Boeing Boeing 307 Stratoliner - СШАUSA - 1938

The second aircraft, c/n 1995 NX19902, continued the testing. This view shows the original tailplane and the long straight fillet added in front of the fin to improve directional stability.

Самолёты на фотографии: Aircrafts on the photo: Boeing Boeing 307 Stratoliner - СШАUSA - 1938

PAA "Clipper Comet" c/n 2002 NC19910 descending with undercarriage down but as yet no flap, shows the tailplane in its first revised form (original production). The later B-17 tailplane had a larger span, less taper and more rounded tips.

Самолёты на фотографии: Aircrafts on the photo: Boeing Boeing 307 Stratoliner - СШАUSA - 1938

Howard Hughes' c/n 1997 NX19904 was the first Stratoliner delivered. It is seen here with tail up on take-off, still with the original tail unit unmodified.

Самолёты на фотографии: Aircrafts on the photo: Boeing Boeing 307 Stratoliner - СШАUSA - 1938

The loss of the prototype left PAA with only 3 Stratoliners, their first being the second aircraft c/n 1995 NX19902 "Clipper Rainbow" seen here during an engine run. The strip of strengthened material can be seen on the fuselage and this was fitted to all the aircraft.

Самолёты на фотографии: Aircrafts on the photo: Boeing Boeing 307 Stratoliner - СШАUSA - 1938

C/n 1996 NX19905 which also shared testing is seen with the original fin and rudder but with the first revision of the tailplane and elevators with servo and trim tabs moved further outboard.

Самолёты на фотографии: Aircrafts on the photo: Boeing Boeing 307 Stratoliner - СШАUSA - 1938

NX19905 again, now with the long straight fin fillet added. Initially TWA's "Comanche" it later became F-BELV and XW-TAB in Laos and was shot down during the Viet Nam war.

Самолёты на фотографии: Aircrafts on the photo: Boeing Boeing 307 Stratoliner - СШАUSA - 1938

One of the duplicated engine driven supercharger units for cabin pressurisation. A is the automatic air supply control unit and B is spent air passing out of the aircraft.

Самолёты на фотографии: Aircrafts on the photo: Boeing Boeing 307 Stratoliner - СШАUSA - 1938

Prototype Stratoliner NX19901 in flight with the two starboard engines shut down and the Hamilton propellers feathered. The pilot is applying a large amount of left rudder to balance the offset thrust.

Самолёты на фотографии: Aircrafts on the photo: Boeing Boeing 307 Stratoliner - СШАUSA - 1938

TWA acted as hosts to 38 British schoolboys evacuated during the Blitz. For publicity purposes the aircraft's name "Zuni" has been replaced with "Stratoliner". The gills (cooling flaps) are seen open on the GR-1820-G102 engines,

Самолёты на фотографии: Aircrafts on the photo: Boeing Boeing 307 Stratoliner - СШАUSA - 1938

One of the two pumps supplying air to the cabin, with arrows showing air in to the pump and out to the cabin supply line.

Самолёты на фотографии: Aircrafts on the photo: Boeing Boeing 307 Stratoliner - СШАUSA - 1938

A stewardess indicates the conditioned pressurisation air flowing in from the roof

Самолёты на фотографии: Aircrafts on the photo: Boeing Boeing 307 Stratoliner - СШАUSA - 1938

For the proposed Round-the-World record flight Hughes had 12 extra fuel tanks fitted in the cabin as seen here looking forward. Four oval section tanks held 212.5 US gallons each and eight rectangular section tanks each held 180 US gallons, a total of 2,290 US gallons (1908 Imperial gallons).

Самолёты на фотографии: Aircrafts on the photo: Boeing Boeing 307 Stratoliner - СШАUSA - 1938

The Stratoliner dual control cockpit. Although both pilots could reach all controls in emergency, the throttles are on the left of the console for the captain with the other controls on the right for the first officer/co-pilot. Both pilots have their own a. v. panel of flying instruments, Sperry autopilot in the centre.

Самолёты на фотографии: Aircrafts on the photo: Boeing Boeing 307 Stratoliner - СШАUSA - 1938

The 'Flight Engineer' at his panel, the pressurisation instruments enclosed by the white line.

Самолёты на фотографии: Aircrafts on the photo: Boeing Boeing 307 Stratoliner - СШАUSA - 1938