Blackburn
TB seaplane

A twin-fuselage seaplane design, intended for anti-Zeppelin operations.
Blackburn Twin Blackburn twin fuselages A close up view of the unique twin-fuselage Blackburn TB seaplane.
 
The Blackburn TB (or Twin-Blackburn) was, as the name suggests, a twin-engine seaplane. However, it was more unusual in that it had two separate fuselages, each with its own engine.
 
The two fuselages were joined together by a 10 ft span centre section forward with a tailplane to the rear. The huge upper wing was some 15 ft wider than the lower wing with the upper tip extension being braced by a triangular 'king post' mounted above the outboard struts.
 
The type was built against a 1915 Admiralty Specification for a 'long-range night interceptor to counter the Zeppelin threat'. The design was originally intended to use a pair of 150 hp Smith engines - an American design that promised light weight and low fuel consumption. In the event however, it proved unsuccessful in trials with the result that eight of the nine Blackburn TB aircraft were finally powered by 100 hp Gnome Monosoupape engines.The last aircraft varied even further by receiving two 110 hp Clerget rotary engines.
 
The first Blackburn TB (1509) was completed in August 1915 and it was joined by another pair (1510) and a  Clerget-powered aircraft (1517) for trials at RNAS Isle of Grain during 1916.
 
Initially, the aircraft was found to be too flexible, causing the aileron wires to slacken which resulted in a much reduced lateral control. This problem was soon remedied however, and the aircraft flew successfully albeit with a modest performance due to the lower-than-intended power available.
 
The Pilot sat in the starboard fuselage with the Observer in the port fuselage and other than via hand signals, there was no means of communication between the two crew. This proved to be a distinct disadvantage during night operations.
 
The sole armament on the TB was the carriage of Ranken incendiary darts, intended to penetrate an airship envelope and then set fire to the gas within. Unfortunately, with the reduced power available and fuel limiting it to just four hours endurance, there was only sufficient payload to carry 70 lb of the steel darts.
 
Seven aircraft were sent to RNAS Killinghome in 1917 but did little flying before being broken up in August of that year.
 
The remaining two aircraft (1511 and 1512) were delivered to store at RNAS Crystal Palace where they too were broken up in July 1917.
 
Blackburn TB twin fuselage seaplane 1517 ground stbd The final Blackburn TB twin fuselage seaplane (1517) on the slipway.

Variants & Numbers Built

Total of nine aircraft (1509 – 1517)
1509, 1510 and 1517 underwent trials at the Isle of Grain, delivered with 1513-1517 to RNAS Killinghome in 1916. 1511, 1512 delivered to store at Crystal Palace. All aircraft had been broken up by August 1917.

Specification

Powerplant
 
Two 100 hp Gnome Monosoupape rotary engines; 1517 two 110 hp Clerget 9b
Span
60 ft 6 in
Maximum Weight
3,500 lb
Capacity & Armament
Two crew: pilot and observer; armament Ranken incendiary steel darts
Maximum Speed
86 mph at sea level
Endurance
4 hours
 

Survivors

No examples survive.