The Bristol Blenheim was a twin-engine high performance all-metal medium bomber aircraft, powered by a pair of Bristol Mercury VIII air-cooled radial engines, each capable of 860 hp (640 kW).
Each engine drove a three-bladed controllable-pitch propeller, and were equipped with both hand-based and electric engine starters.
To ease maintenance, the engine mountings were designed with a split-segment to facilitate rapid engine removal without disturbing the carburettors.
A pair of fuel tanks, each containing up to 140 gallons, were housed within the center-section of the fuselage.

The fuselage of the Blenheim employed a light-alloy monocoque structure using open-section stringers, and was constructed in three sections.
The wing is also built in three sections, the center-section of which is bolted and rivetted to the fuselage.
The outer wing sections are tapered in chord and thickness.
Extensive use of Alclad sheeting is made in elements such as the ribs, skin, flaps, and web reinforcement of the spars.
The tail unit is of a cantilever monoplane style, using an all-metal tailplane and fin while the aerodynamically-balanced rudder and elevators use a metal frame covered with fabric.
The undercarriage was hydraulically-retracted, with an auxiliary hand-pump for emergency actuation; medium-pressure tyres were used, complete with pneumatically-actuated differentially-control brakes.

The Blenheim typically carried a crew of three – pilot, navigator/bombardier and wireless (radio) operator/air gunner.
The pilot's quarters on the left side of the nose were so cramped that the control yoke obscured all flight instruments while engine instruments eliminated the forward view on landings.
Most secondary instruments were arranged along the left side of the cockpit, essential items such as the propeller pitch control were actually placed behind the pilot where they had to be operated by feel alone.
The navigator/bombardier was seated alongside the pilot, and made use of a sliding/folding seat whilst performing the bomb aiming role.
Dual flight controls could be installed.
The wireless operator/air gunner was housed aft of the wing alongside the aircraft's dorsal gun turret.

Armament comprised a single forward-firing .303 in (7.7 mm) Browning machine gun outboard of the port engine and a .303 in (7.7 mm) Lewis Gun in a semi-retracting Bristol Type B Mk I dorsal turret firing to the rear.
From 1939 onwards, the Lewis gun was replaced by the more modern .303 in (7.7 mm) Vickers VGO machine gun of the same calibre.
A 1,000 lb (450 kg) bomb load could be carried in the internal bomb bay set into the center section of the fuselage.
Like most contemporary British aircraft, the bomb bay doors were kept closed with bungee cords and opened under the weight of the released bombs.
Because there was no way to predict how long it would take for the bombs to force the doors open, bombing accuracy was consequently poor.
The bomb bay could be loaded using a hand-operated winch incorporated into the fuselage.

To achieve its relatively high speed, the Blenheim used a very small fuselage cross-section, with its upper front glazing all at one angle in the form of a "stepless cockpit" that used no separate windscreen panels for the pilot, a notable feature of a substantial majority of German bomber designs, first conceived during the war years.
Both fixed and sliding window panels were present, along with a transparent sliding roof.
Other onboard equipment included a radio, cameras, navigation systems, electric lighting, oxygen apparatus, and  stowage for parachutes and clothing.
The Bristol Blenheim was a twin-engine high performance all-metal medium bomber aircraft, powered by a pair of Bristol Mercury VIII air-cooled radial engines, each capable of 860 hp (640 kW). Each engine drove a three-bladed controllable-pitch propeller, and were equipped with both hand-based and electric engine starters. To ease maintenance, the engine mountings were designed with a split-segment to facilitate rapid engine removal without disturbing the carburettors. A pair of fuel tanks, each containing up to 140 gallons, were housed within the center-section of the fuselage.
The fuselage of the Blenheim employed a light-alloy monocoque structure using open-section stringers, and was constructed in three sections. The wing is also built in three sections, the center-section of which is bolted and rivetted to the fuselage. The outer wing sections are tapered in chord and thickness. Extensive use of Alclad sheeting is made in elements such as the ribs, skin, flaps, and web reinforcement of the spars. The tail unit is of a cantilever monoplane style, using an all-metal tailplane and fin while the aerodynamically-balanced rudder and elevators use a metal frame covered with fabric. The undercarriage was hydraulically-retracted, with an auxiliary hand-pump for emergency actuation; medium-pressure tyres were used, complete with pneumatically-actuated differentially-control brakes.
The Blenheim typically carried a crew of three – pilot, navigator/bombardier and wireless (radio) operator/air gunner. The pilot's quarters on the left side of the nose were so cramped that the control yoke obscured all flight instruments while engine instruments eliminated the forward view on landings. Most secondary instruments were arranged along the left side of the cockpit, essential items such as the propeller pitch control were actually placed behind the pilot where they had to be operated by feel alone. The navigator/bombardier was seated alongside the pilot, and made use of a sliding/folding seat whilst performing the bomb aiming role. Dual flight controls could be installed. The wireless operator/air gunner was housed aft of the wing alongside the aircraft's dorsal gun turret.
Armament comprised a single forward-firing .303 in (7.7 mm) Browning machine gun outboard of the port engine and a .303 in (7.7 mm) Lewis Gun in a semi-retracting Bristol Type B Mk I dorsal turret firing to the rear. From 1939 onwards, the Lewis gun was replaced by the more modern .303 in (7.7 mm) Vickers VGO machine gun of the same calibre. A 1,000 lb (450 kg) bomb load could be carried in the internal bomb bay set into the center section of the fuselage. Like most contemporary British aircraft, the bomb bay doors were kept closed with bungee cords and opened under the weight of the released bombs. Because there was no way to predict how long it would take for the bombs to force the doors open, bombing accuracy was consequently poor. The bomb bay could be loaded using a hand-operated winch incorporated into the fuselage.
To achieve its relatively high speed, the Blenheim used a very small fuselage cross-section, with its upper front glazing all at one angle in the form of a "stepless cockpit" that used no separate windscreen panels for the pilot, a notable feature of a substantial majority of German bomber designs, first conceived during the war years. Both fixed and sliding window panels were present, along with a transparent sliding roof. Other onboard equipment included a radio, cameras, navigation systems, electric lighting, oxygen apparatus, and  stowage for parachutes and clothing.
Bristol Blenheim