ASN logo
ASN Wikibase Occurrence # 204426
Last updated: 17 November 2021
This information is added by users of ASN. Neither ASN nor the Flight Safety Foundation are responsible for the completeness or correctness of this information. If you feel this information is incomplete or incorrect, you can submit corrected information.

Date:07-APR-1940
Time:
Type:Blackburn B-20
Owner/operator:Blackburn Aircraft
Registration: V8914
MSN:
Fatalities:Fatalities: 3 / Occupants: 5
Other fatalities:0
Aircraft damage: Written off (damaged beyond repair)
Location:Firth of Clyde, off Gourock Head, Isle of Bute, Scotland -   United Kingdom
Phase: En route
Nature:Test
Departure airport:Dumbarton
Destination airport:
Narrative:
The Blackburn B20 is one of the least known British aircraft designs of the Second World War. Although the project was abandoned in 1940 its existence was kept hidden until June 1945. What was so special about this aeroplane to warrant this level of secrecy?

Between the World Wars the design of flying boats had proceeded at a fantastic pace. By the mid 1930s giant four engined flying boats such as the Shorts "C" class and the Boeing Clipper were on the drawing board. The need to keep the propellers clear of the water meant that such designs had deep fuselages, far from streamlined. One way around this problem was to mount the wings and engines high above the fuselage on a pylon or struts, such as in the Consolidated Catalina and Dornier Wal designs, but such installations still produced drag. In 1936 Major J.D. Rennie, chief seaplane designer for the Blackburn Aircraft Company put forward a revolutionary design to meet Air Ministry Specification R1/36. His radical idea was to have the entire bottom of the flying boat hull able to be extended downwards for landing, and be retracted for flight, giving a slim streamlined fuselage and the promise of unprecedented speed for a flying boat.

Three companies tendered designs for R1/36, along with the Blackburn proposal Saro and Supermarine both put forward projects (the Supermarine type 314 tendered was one of the last design projects RJ Mitchell had a hand in). The Air Ministry chose the Saro S36 Lerwick to meet Specification R1/36 (the Lerwick proved an expensive failure, seeing only limited service and only 21 were produced), but was sufficiently impressed with the Blackburn design to authorise the building of two prototypes. It was originally intended to use two Bristol Hercules engines, but as design and construction commenced the design weight of the aircraft grew and it became obvious that to fully realise the high-speed potential of the B20 more powerful engines were needed. The only choice available was the Rolls-Royce Vulture 24 cylinder of 1,700 hp. When war broke out in 1939 the second prototype was cancelled and any chance of a production order was lost, factory resources were devoted to types already in production (Blackburn built Short Sunderland flying boats) and Consolidated Catalinas were purchased from the USA. This is understandable since at the time the pressing need was for aircraft to patrol the Atlantic approaches and seek out U-boats, the high speed of the B20 was simply not seen as an advantage. If you had told anyone in Coastal Command or the Admiralty that by mid 1940 the Atlantic seaboard from the far north of Norway to the Bay of Biscay would be in Nazi hands and used as bases for long range FW Condor patrol aircraft and Ju88 long range fighters you would have been laughed at!

However there was little doubt that the single B20 prototype nearing completion showed great promise and so flight trials were allowed to go ahead to glean data for future designs. It was nicknamed the "nutcracker", referring to the fate of anyone on the central float when it was retracted. The B20 took to the air in March 1940. On the first flight it was found that there was a problem with the aileron trim and it took four or five more test flights to sort this out (there were no trim tabs on the ailerons and alterations could only be done on the ground). In the process it had a birdstrike and repairs had to be carried out.

On 7 April 1940, the B20 (now bearing RAF serial V8914) took to the air from Dumbarton for its first attempt at a high speed run. The pilot was Blackburn test pilot Flt Lt Harry Bailey, with him were Ivan Waller, a Rolls-Royce flight test engineer, Fred Weeks, a Blackburn flight test engineer, and Duncan Roberts and Sam McMillan, both Blackburn aircraft riggers along to monitor instruments during the flight. The flight that day was over the Forth of Clyde and Sound of Bute on Scotland west coast. A high speed run took place at which a speed of 345 mph was reached, but shortly afterwards severe vibration set in. Reducing speed did not help and Flt Lt Bailey ordered the crew to take to their parachutes. Up in the cockpit Fred Weeks was able to get out of one of the escape hatches in the roof, but Ivan Waller deployed his chute too early and it got caught in the radio mast with him only half way out of the escape hatch. Then the vibration stopped and Ivan was able to climb along the top of the fuselage, untangle his parachute and drop free. Flt Lt Bailey stayed with the aircraft until the last possible moment to give the other two crew members a chance to escape, his parachute did not open fully and he was drowned. The aircraft crashed into the sea off Gourock Head, Isle of Bute. No trace was ever found of Duncan Roberts and Sam McMillan. The two surviving crew members were rescued by the improbable sounding HMS Transylvania (a merchant ship converted in an auxiliary cruiser). The crew of the Transylvania reported seeing a large rectangular unit come down out of the thick cloud cover, probably an aileron. The most likely explanation for the crash is that the initial vibration was aileron flutter, this ceased when the aileron broke free (giving Ivan Waller his chance to free his parachute). But with the loss of an aileron the aircraft would have been uncontrollable, leading to its crash. With the loss of the one and only example of the B20 the project ended.

Sources:

http://www.dingeraviation.net/B20/blackburn_b20.htm
http://www.thunder-and-lightnings.co.uk/memorial/entry.php?id=47
https://en.wikipedia.org/wiki/Isle_of_Bute
http://wikimapia.org/#lang=en&lat=55.835690&lon=-5.056360&z=11&m=w
https://www.helensburghadvertiser.co.uk/news/18177661.eye-millig-three-men-died-1940-flying-boat-tragedy/


Revision history:

Date/timeContributorUpdates
14-Jan-2018 20:14 Laurent Rizzotti Added
05-May-2018 15:56 Anon. Updated [Source]
22-Jan-2020 07:37 gerard57 Updated [Other fatalities, Source]

Corrections or additions? ... Edit this accident description