The Blackburn G.P, or General Purpose Seaplane, was an attempt by the company
to remedy the embarrassing failure of the twin-fuselage Blackburn TB and restore
confidence within the admiralty. Built as a private venture, it was designed by Bob Copley,
who had worked on the ill-fated TB, and was proposed to the Admiralty as a three-seat,
long-range, anti-submarine patrol bomber. Though it inherited several design features
of the Twin-Blackburn, the G.P had a far more conventional layout,
and most importantly it didn’t try to set itself on fire every time the engine was started.
It featured a single long, slim fuselage that would accommodate a pilot and two gunners,
one of the latter also serving the role of bomb or torpedo aimer. The wings were
almost a direct carry-over from the old T.B, with the upper being braced by Kingposts and
having a significantly greater span. Both wings were of parallel chord and without stagger,
both had a significant amount of dihedral, and they were designed
to be folded back for ease of storage. The first G.P that was built was powered by
a pair of Sunbeam Nubian engines, each producing 150hp. They drove wooden four-bladed propellers,
and were cooled by a pair of radiators mounted vertically to the wing struts. The structures
that supported the engine also formed part of that which supported to the two main floats;
these were bungee sprung to help absorb impact on the water, and they were built
up of 12 individual, water tight compartments that were housed in a treated plywood covering.
The first aircraft was completed in the Summer of 1916, and with the serial number 1415 it flew for
the first time at RNAS Isle of Grain in July. In its complete form, the G.P represented a potent
aircraft, at least for one flying in 1916. The gunners each had a .303 calibre Vickers
machine gun mounted on a flexible scarf ring, providing the aircraft with two independent
arcs of defensive fire. When they were more inclined towards offensive fire, the forward
gunner could operate a bomb sight that was mounted externally on the starboard side of their cockpit.
Though the details of the bomb sight appear to be unknown, the aircraft’s
payload was known to be either four 230 lb bombs (slung on underwing racks), or a single
torpedo that was carried beneath the fuselage. Though there is no evidence to show that the GP
was ever flown with said torpedo during tests, it was among the first twin-engine aircraft capable
of doing so. That being said, the single-engine Short 184 had already been successfully using
torpedoes since the summer of 1915, and the Blackburn had to rely on other merits if it
were to be more attractive to the Admiralty. The greatest of these was hoped to be its range and
endurance, it had enough fuel to fly for up to eight hours when carrying bombs or a torpedo,
which was significantly greater than the 2 ¾ hour endurance of the Short 184.
The evaluation of the Blackburn’s endurance was taken to the extreme in August 1916, when it was
taken out and moored in rough seas to see how long it would last. It endured the aquatic beatdown for
several days until finally giving out, and its believed the data from this experiment was used
to make changes to the second Blackburn G.P – who’s construction began shortly afterwards.
This aircraft was built with a considerably reinforced structure. Heavier-gauge fittings were
used throughout the airframe, and some changes were made to the construction of the wing-struts;
details on these latter changes are scarce but their thickness appears to have increased by about
10-20 percent. These changes were made due to an admiralty requirement which called for strength
factors of 5 and 4 on the front and rear struts respectively, to make the wings more durable
when the aircraft was operating in rough seas. Along with the reinforcements, the second G.P also
had a few modifications that set it apart from its predecessor. Instead of two, it had four ailerons;
two of increased length on the upper wing, and a pair of shorter ailerons on the lower wing. The
engines, too, were changed. Power now came from a pair of 190hp Rolls-Royce Falcons (though they
had not yet received that name), which, like the Sunbeams, drove a pair of four blade propellers.
But, unlike the Sunbeams, the Rolls-Royces had exhaust manifolds on the outside walls of the
cylinder blocks, which meant the exhaust pipes could run along the side of the engine nacelles,
rather than stick out from over the top. One other change that set the second GP apart,
though it is difficult to see in most of the photos, was the unfortunate decision to use a
wire trailing edge on the wings. This resulted in the familiar scalloped pattern that could be seen
of many aircraft of this time, but it was poorly suited to seaplanes. Wire and salt water did not
go well together, and after no great time had elapsed the corrosion of said wire would lead
to damage of the wing fabric and require a trip back to the hanger for replacement or repairs.
Corroding wings aside, the Blackburn GP was an improvement over its predecessor,
but it never went into production. Existing aircraft, particularly the Short 184, performed
the roles of anti-shipping and anti-submarine duties perfectly well, and it was felt that the
blackburn was too big and too expensive for the rough, unforgiving environment of naval use.
Indeed, said rough, unforgiving environment was nearly the end for some of the people testing
the second prototype. Its manufacturer trials were conducted on the Humber esturary during
the winter of 1916/17. Launching the aircraft was simple enough, but bringing it back in required
a team to wade into the icy waters; the tide was particularly strong that day, and cold,
in fact it even brought in sea ice from the North Sea. By the time the crew had gotten the aircraft
onto dry land they were in a seriously bad way, all of them looked blue, some were incapable of
speaking, and none of them could walk. They were carried into the hangar on makeshift stretchers,
their clothes literally frozen onto their skin, and a series of small fires
were made where they were gradually thawed out. After this frosty experience the aircraft was sent
to Great Yarmouth Air Station for service trials, where, as mentioned before it was not considered
suitable enough for a production contract. However, it was recognised that the aircraft
on the whole was still a promising machine, and it was suggested that a landplane version of the GP
could be of great use, as it wouldn’t have to worry about the challenges of water handling.
This led to the development of the blackburn Kangaroo, but that’s a story for another day.
As always, thank you all so much for watching, and a big thank you of course to the Patreons.
I’m probably going to do more of these shorter videos on interwar aircraft over the next few
months, as my list of aircraft to cover has now exceeded 500 items.
However, longer videos will still be getting made on the more popular machines. A big thank
you of course to our wing commander tier patreon supporters, our highest tier members, and warm
welcome to Steven Eldred, who is the newest member of this special group. Hopefully, this
video actually gets to Patreon on time for once -there have been a lot issues with Patreon video
recently- and hopefully I wont have to re-upload it THREE times like the Curtiss video. We’ll see.
Anyway, thank you all for your continued support, and I’ll catch you all next time. Goodbye.