Today we’re taking a look at two aircraft, the Airspeed AS.39, and the General Aircraft GAL.38,
perhaps two of the worst planes ever built. Additionally, they were amongst some of the
most unflattering designs to take to the sky, a fact that is rendered comical when it is to be
considered that they were designed with stealth in mind. But, thankfully, it was not visual
stealth that was important for these planes…at least not completely, for they were designed
to be operated at night by the Fleet Air Arm. In the late 1930s, with the threat of war looming
ever closer, the Admiralty was exploring new ways of identifying and tracking enemy fleet movements.
Radar was considered the most promising solution, but in 1937 the technology was
not quite yet ready for Naval applications, and a stop-gap solution was looked for.
After radar, the idea of using aircraft for visual spotting was the next logical choice.
But traditional spotting planes had two main drawbacks. 1) They were relatively noisy,
and the sounds of an unidentified plane flying overhead would usually persuade
an enemy fleet change course, and, if near the coast, call in interceptors.
2) Even if they managed to not arouse suspicion by flying numerous circles around the enemy fleet,
they could not follow the fleet for more than an hour or so before running out of fuel.
As a result of these considerations, the Admiralty drew up a series of requirements
for a new aircraft that they would later call a ‘Night Shadower’ – though later this would
change to ‘Fleet Shadower’. This called for a carrier-based aircraft suitable for the purpose
of shadowing an enemy fleet at night, it must be able to fly as slowly and silently as possible,
and it must have an endurance of at least six hours.
After receiving submissions from five different manufactures,
the decision was made to go ahead with the designs submitted by Airspeed and General Aircraft.
Specification S.23/37 was then issued to the two companies on the 23rd of October 1937,
officially outlining and expanding upon the Admiralty’s direct requirements.
As far as specifications go, this one was perhaps one of the most stringent when it
came to the desired dimensions and performance figures, and as a result of this the two aircraft
were remarkably similar in appearance and layout – hence why I am covering them both the same video.
Along with the carrier requirement, and a minimal endurance of 6 hours,
there was a collection of other non-negotiable requirements to address. Individually, they were
achievable, but when rolled into one collective specification they presented such an engineering
headache that the draftsmen probably questioned the mental faculty of the person who originally
drew up the specification itself. Now I’m not going to read through the
entire Naval specification to explain the sheer impossibility of this challenge, and
in fact beating my face against a wall would be preferable, so instead I shall provide you with
a rex’s hangar-certified version of events. (Somewhere in the Admiralty)
‘Right chaps, we need you to build a smashing new aircraft to stalk the enemy fleet.’
‘Alright, shouldn’t be too much of a problem. What do you need?’
‘Firstly, it must be able to observe the enemy fleet from a low altitude undetected,
which means you have to build it to fly as silently as possible.’
‘Okay…we could use the Pobjoy Niagara engines.
They’re low power, but with the right airscrew they’d be very quiet.’
‘Excellent, it also needs a crew of three, and an operational endurance of at least six hours.’
‘Oh…well we’d probably need more than two engines installed to manage that,
four would be more the mark, and with-‘ ‘It cannot exceed 10,000 lbs in weight.’
‘With four engines?’ ‘It also needs to have folding
wings for carrier operations.’ ‘Hang on, with four engines?’
‘And it needs a take-off run of less than 200 feet.’
‘Now wait a minute’ ‘And it must have an
operational speed of just 39 knots, so that it can really stalk the enemy without wasting fuel.’
‘Oh Christ.’ If that sounded like a scene
out of something like Blackadder, or Dad’s Army, then I don’t blame you, because the requirements
for the fleet shadower really were comically impossible…but they went ahead with it anyway.
Airspeed and General aircraft worked on prototype production throughout 1939
and both were ready for their first flights in 1940. Though the aircraft were remarkably similar,
there were still some differences that told them apart. The General Aircraft plane had a
nosewheel-type undercarriage, whereas the Airspeed model had a long-track tailwheel assembly – this
latter design was chosen to give better characteristics for level-landing on carriers,
but it lacked the natural stability enjoyed by the tricycle arrangement.
Both aircraft were built of a mixed construction, with the high-mounted, strut-braced wings being
made of spruce and plywood, whilst the fuselage was made with metal. On the Airspeed model,
and perhaps the General Aircraft too, the wing was designed for buoyancy in case of ditching,
with the sections between the spars being made watertight. After much trial and error,
each outer wing, complete with two engines and at least 380 litres of fuel, was able to be
folded from the root, and during storage a jury strut supported the wing at the forward spar.
As originally intended, the Pobjoy Niagara engines powered both planes,
and the ability to maintain long-distance cruising speeds below 40 knots was made possible
using slipstream action over a combination of slotted flaps, slotted ailerons, and split-flaps.
Though designs had been drawn up around the Niagara V engine, development problems with the
powerplant led to the General Aircraft prototype to be equipped with the lower powered Niagara
III. The Airspeed model was completed slightly later and retained the original Niagara Vs.
As one of the many requirements of the specification, an exceptional field of view
had to be provided for the pilot and observer. The latter was accomplished in a nose compartment with
front and side windows, whilst the pilot’s cockpit was on a separate raised floor. On the airspeed
aircraft at least, this cockpit was also offset slightly to port, to both improve visibility for
landing and also to provide an internal passageway to the station of the radio operator.
As expected of aircraft built to near-impossible requirements,
the results from the initial test flights were mixed at best, and downright dangerous at worst.
The Fleet Shadower built by General Aircraft flew first, taking off on the 13th of May 1940.
Though it now had less-powerful engines, the innovative feature of using the propwash to
generate additional lift was still enough to keep it airborne at the required speeds. In fact, with
the full-span flaps deployed just so, it could maintain a stable speed of just 39 mph – which
meant the aircraft could almost slow down to match the speed of the fleets it was meant to follow.
But, this amazingly slow speed brought its own problems. Fleets, funnily enough, operate at sea,
and at an altitude of 1500 feet the winds blowing over said sea
tended to be rather contrary. Further testing of the aircraft revealed a litany of stability
problems at cruising speeds in anything other than perfect weather. As a result of this the
prototype went back for a series of modifications, chief of which was the replacement of the triple
tailfin with a large single unit. The changes yielded…some improvement,
but no further development was made as Admiralty interest had shifted away to the use of radar.
A second prototype that was under construction was scrapped, and the first aircraft only flew
for a few more months before it too was scrapped in the spring of 1942.
The Airspeed Fleet Shadower was even more disappointing. The rate of climb was,
as expected, poor; there was a large nose-down change of trim when the throttles were closed;
the elevators were deemed to be ineffective; and most alarmingly was the tendency for a
premature stall, the result of unexpected areas of disturbed airflow over the wing.
For an aircraft designed to fly as slow as possible, unexpected stalling was even less
desirable than usual. Further investigations found that its engines were just powerful
enough to provide the right amount of propwash for additional lift, and anything below 75%
power resulted in ever increasing stall risks. Airspeed was asked to re-engine the prototype with
more powerful Armstrong-Whitworth Cheetah engines, but this was never done. By the beginning of 1942,
radar was now being used on long-range patrol aircraft, thus rendering the requirement of the
fleet shadower utterly obsolete. Additionally, the use of the Cheetah engines in the aircraft
would have done away with its so-called ‘stealthy silence’. Like its sister plane, the
Airspeed model was scrapped in the spring of 1942, closing the brief chapter of a book that probably
shouldn’t have been written in the first place. As always thank you all so much for watching,
and a big thank you of course to the Patreons, with a special shout out to Kevin,
Delliardo, Bane, FB, Christopher R, Tronathon, Erik Hindman, John Austin Jr, Ray Culotta, Keith
Tarrier, Greenseaships, Northlincsweb, MCT, Ted Parsons, and Capitano Lorenzo for their support as
Wing Commander Tier Patreons. Thank you Capitano, thank you all, and I’ll catch you next time.