The Bristol Blenheim 

Great Britain
Great Britain

Sorry, No ID pictures yet

To prove the Air Ministry that they were wrong to focus on bi-planes, Lord Rothermere let it be known that he was interested in a modern, fast, monowing transport with retractable gear, and fully made of metal. Bristol drew up a design, known as Type 135, and showed the results to his Lordship. Rothermere placed an order for a type 135, fitted with the new Mercury powerplant, further known as Type 142.
Within a year the first Blenheim had test flights, and proved that it was 50 Mph (80 kph) faster than the bi-wing fighter of Gloster called the Gladiator. The fighter had just been ordered into production, after it won a contest amongst other bi-plane fighters. Lord Rothermere was proved to be right, and the Air Ministry got interested in the Blenheim. As it turned out Lord Rothermere was unable to order one for himself, because the whole production of Bristol was to be dedicated for military aircraft.

Although badly outclassed when the war broke out, the Blenheim was used extensively due to lack of a successor. The only role in which it made an impression was that of the night fighter, fitted with radar. It did prove however the fact that sticking to bi-planes was a dangerous thought, and thus paved the way for advanced fighters and bombers.

Versions:

Further pictures:

Bristol Blenheim in full flight
Bristol Blenheim in full flight

 

Technical data on the Bristol Blenheim Mk I
Powerplant 2 × Bristol Mercury VIII radials, rated at 840 hp (626.21 kW) each Role during war
  • (Ground) Attack Fighter
  • Night-Fighter
  • Light Bomber
  • Advanced Trainer
Length 39 ft 9 inch Height 9 ft 10 inch
Empty weight 8840 lb Operational weight 12500 lb max
Wing Span 56 ft 4 inch Wing Aspect ratio 6.77
Wing Area 469 sq ft Service ceiling 27280 ft
Maximum speed 285 mph at 15000 ft Cruising speed 200 mph at optimum altitude
Initial climb rate 1,540 ft per minute,
Climb to 15,000 ft in 11 minutes 30 seconds
Range 1125 miles typical
Fuel capacity internal 280 Imp gal (336 US gal) Fuel capacity external -
Machine guns
  • 1 × 0.303 inch fixed forward-firing in port wing, 400 rounds
  • 1 × 0.303 inch trainable in powered dorsal turret
Cannons -
Bomb load Up to 1,000 lb in lower fuselage weapons-bay, and generally consisting of 2 × 500 lb bombs, or 4 × 250 lb bombs, or 24 × 40 lb bombs Torpedoes/rockets -
Crew 3: pilot, navigator/bombardier, radio operator/gunner Naval or ground based Ground
First flight (prototype) 25 June 1936 Operational Service March 1937 - 1956
Manufacturer Bristol Aeroplane Co. Ltd. Number produced 6899 total, 1443 this version
Metric system
Length 12.12 m Height 3 m
Empty weight 4010 kg Operational weight 5670 kg max
Wing Span 17.17 m Wing Aspect ratio 6.77
Wing Area 43.57 m² Service ceiling 8315 m
Maximum speed 459 km/h at 4572 m Cruising speed 322 km/h at optimum altitude
Initial climb rate 469 m per minute,
Climb to 4570 m in 11 minutes 30 seconds
Range 1810 km typical
Fuel capacity internal 1272 liters Fuel capacity external -
Machine guns
  • 1 × 7.7 mm fixed forward-firing in port wing, 400 rounds
  • 1 × 7.7 mm trainable in powered dorsal turret
Cannons -
Bomb load Up to 454 kg in lower fuselage weapons-bay, and generally consisting of 2 × 227 kg bombs, or 4 × 113 kg bombs, or 24 × 18 kg bombs Torpedoes/rockets -

Technical data on the Bristol Blenheim Mk IVL
Powerplant 2 × Bristol Mercury XV radials, rated at 995 hp (741.76 kW) each Role during war
  • Night-Fighter
  • Light Bomber
  • Reconnaissance Aircraft
  • Advanced Trainer
Length 42 ft 7 inch Height 12 ft 9.5 inch with the tail down
Empty weight 9790 lb Operational weight 13500 lb typical
Wing Span 56 ft 4 inch Wing Aspect ratio 6.77
Wing Area 469 sq ft Service ceiling 22000 ft
Maximum speed 266 mph at 11800 ft Cruising speed 198 mph at optimum altitude
Initial climb rate 1,500 ft per minute Range 1460 miles typical,
1950 miles max
Fuel capacity internal 468 Imp gal (562 US gal), plus provision for 2 × 50 Imp gal (60 US gal) weapons-bay tanks Fuel capacity external -
Machine guns
  • 1 × 0.303 inch fixed forward-firing in port wing, 400 rounds
  • 2 × 0.303 inch trainable in powered dorsal turret
  • 2 × 0.303 inch trainable rearward-firing in undernose blister
Cannons -
Bomb load Up to 1,000 lb in lower fuselage weapons-bay, and generally consisting of 2 × 500 lb bombs, or 4 × 250 lb bombs, or 24 × 40 lb bombs Torpedoes/rockets -
Crew 3: pilot, navigator/bombardier, radio operator/gunner Naval or ground based Ground
First flight (prototype) 25 June 1936 Operational Service March 1937 - 1956
Manufacturer Bristol Aeroplane Co. Ltd. Number produced 6899 total, 3306 Mk IV version
Metric system
Length 12.98 m Height 3.9 m with the tail down
Empty weight 4441 kg Operational weight 6124 kg typical
Wing Span 17.17 m Wing Aspect ratio 6.77
Wing Area 43.57 m² Service ceiling 6706 m
Maximum speed 428 km/h at 3597 m Cruising speed 319 km/h at optimum altitude
Initial climb rate 457 m per minute Range 2350 km typical,
3138 km max
Fuel capacity internal 2127 liters, plus provision for 2 × 227 liters weapons-bay tanks Fuel capacity external -
Machine guns
  • 1 × 7.7 mm fixed forward-firing in port wing, 400 rounds
  • 2 × 7.7 mm trainable in powered dorsal turret
  • 2 × 7.7 mm trainable rearward-firing in undernose blister
Cannons -
Bomb load Up to 454 kg in lower fuselage weapons-bay, and generally consisting of 2 × 227 kg bombs, or 4 × 113 kg bombs, or 24 × 18 kg bombs Torpedoes/rockets -

Technical data on the Bristol Blenheim Mk VD
Powerplant 2 × Bristol Mercury XXX radials, rated at 950 hp (708.22 kW) each Role during war
  • Light Bomber
  • Reconnaissance Aircraft
  • Advanced Trainer
Length 43 ft 11 inch Height 12 ft 9.5 inch with tail down
Empty weight 11000 lb Operational weight 17000 lb typical
Wing Span 56 ft 4 inch Wing Aspect ratio 6.77
Wing Area 469 sq ft Service ceiling 31000 ft
Maximum speed 260 mph at optimum altitude Cruising speed unknown
Initial climb rate unknown Range 1600 miles max
Fuel capacity internal 468 Imp gal (562 US gal), plus provision for 2 × 50 Imp gal (60 US gal) weapons-bay tanks Fuel capacity external -
Machine guns
  • 2 × 0.303 inch trainable in powered dorsal turret
  • 2 × 0.303 inch trainable rearward-firing in undernose blister
Cannons -
Bomb load Up to 1,000 lb in lower fuselage weapons-bay, and generally consisting of 2 × 500 lb bombs, or 4 × 250 lb bombs, or 24 × 40 lb bombs Torpedoes/rockets -
Crew 3: pilot, navigator/bombardier, radio operator/gunner Naval or ground based Ground
First flight (prototype) 25 June 1936 Operational Service March 1937 - 1956
Manufacturer Bristol Aeroplane Co. Ltd. Number produced 6899 total, 945 Mk V version
Metric system
Length 13.39 m Height 3.9 m with tail down
Empty weight 4990 kg Operational weight 7711 kg typical
Wing Span 17.17 m Wing Aspect ratio 6.77
Wing Area 43.57 m² Service ceiling 9449 m
Maximum speed 418 km/h at optimum altitude Cruising speed unknown
Initial climb rate unknown Range 2575 km max
Fuel capacity internal 2127 liters, plus provision for 2 × 227 liters weapons-bay tanks Fuel capacity external -
Machine guns
  • 2 × 7.7 mm trainable in powered dorsal turret
  • 2 × 7.7 mm trainable rearward-firing in undernose blister
Cannons -
Bomb load Up to 454 kg in lower fuselage weapons-bay, and generally consisting of 2 × 227 kg bombs, or 4 × 113 kg bombs, or 24 × 18 kg bombs Torpedoes/rockets -

Here is a quick overview of all different versions, without the full technical specifications:

Different versions of the Bristol Blenheim 
Bristol Blenheim Mk I Initial production model, and very popular (until the start of the War), also outside Great Britain. The lack of an improved design in 1938 meant that the Blenheim continued to be used by a number of operators, such as he RAF, even though the Air Ministry had recognised the fact that it was already outclassed substantially by monowing fighters. The continual use of the Blenheim led to severe losses.
Number built: 1443
Bristol Blenheim Mk IF Long range heavy day/night fighter version. Added to the standard Mk I were some additional armor, reflector gunsight and 4 ventral carried 0.303 inch (7.7 mm) machineguns. The nose became less glazed to avoid the pilot being blinded during night sorties. Because of bad performances against more heavily armed single-seat monowing fighters, the Blenheim Mk IF was to be used exclusively as a night fighter. In that role it received the AI Mk III, later Mk IV radar. The IF's were phased out by the Beaufighter, but gained fame in the winter of 1940-1941 as the most effective night fighter of the RAF. All Mk IF's are conversions of the Mk I's
Number converted: about 200
Bristol Blenheim Mk IV In an attempt to upgrade the Mk I, the Mk IV and Bolingbroke Mk I (essentially the same) were devised. It had a longer nose, outer wing tanks, more potent powerplants (Mercury VIII's, later Mercury 25's).
Number built: 80
Bristol Blenheim Mk IVL The intended long range version of the Mk IV, with the outer wing tanks in use, and the powerplants changed to Mercury XV.
Number built: 3808
Bristol Blenheim Mk IVF Like the Mk IF was a night-fighter modification to the Mk. I, the Mk IVF was the fighter modification of the Mk IV. It had added some additional armor, reflector gunsight, 4 ventral carried 0.303 inch (7.7 mm) machineguns and extra radio equipment. This type, unlike the Mk IF, was used for day and night operations. The night versions received the AI Mk III, and later the AI Mk IV radar. An unknown number were converted form the Mk. IVL version.
Number converted: unknown
Bristol Bolingbroke Mk I This is the Canadian version of the Bleheim Mk. IV, built by Fairchaild Aircraft Company. These aircraft were powered by Mercury VIII's, imported from Great Britain
Number built: 18
Bristol Bolingbroke Mk IV Intended for use as reconnaissance aircraft, a number of modifications were added to the Bolingbroke Mk I. First, the powerplants were Mercury XV. Furtermore it had a life-raft, interchangeable landing/ski gear, and de-icing boots on the flying surfaces.
Number built: 137
Bristol Bolingbroke Mk IV-W It was feared that the German U-boats (which were then at their peak) would torpedo all British built powerplants, so the Canadian government took steps to have an alternative. The Mk IV-W was equiped with 2 × Pratt & Whitney R-1535-SB4-G Twin Wasp Juniors, rated at 825 hp (615 kW) each. Because the deliveries continued mostly unhampered, the production of these models stopped. Later adoptions saw the use of the Mercury XX radials rated at 820 hp (613 kW), to be able to use lower octane fuel (93 octane) than the Mercury VIII was optimised for (100 octane).
Number built: 14
Bristol Bolingbroke Mk IV-T The change of U-boat activity preemted further use of the Mk. IV, thus the remaining aircraft were delivered as trainers for navigation and gunnery.
Number built: 457
Bristol Blenheim Mk V Also called the Bisley Mk I, this aircraft was to be used for close air support and low-level bombing raids. It was fitted with 2 Bristol Mercury XVI radials, rated at 950 hp (708 kW). More changes concerning armament and armor, and the use of the Mercury XXV and XXX powerplants revised the type's name back to Blenheim, Mk V this time. Mk VA was to be a bomber version, Mk VB to be an attack fighter. The Mk VC was a trainer with dual controls without dorsal turret, and the Mk VD was the tropicalized version of the Mk VA.
Number built: at least 942 (Turkish numbers unavailable)
Bristol Bisley Mk I See the Bristol Blenheim Mk V
Redesignated aircraft

Remarks:

The Blenheims most notable feats were the succesfull night-fighter role during the winter of 1940-1941, and the fact that it convinced the Air Ministry that monowing aircraft were superior to bi-wing aircraft. Imagine what would have happened if all Great Britain had were bi-plane Gloster Gladiators...

Strengths:

Weaknesses:

 

 

© by Frans Bonné, 2000
Last revision: 9/20/00