Recently we looked at the Curtiss SOC seagull, and today we’re taking a look at
the plane that was designed to replace it, but ultimately failed to do so: the SO3C Seamew.
Development work on the Seamew began in 1937. At the start of the year, Curtiss and Vought,
the US Navy’s main suppliers of catapult scout planes, were approached to submit designs for
a high-speed replacement of the SOC Seagull. The naval specification called for a mid-wing
monoplane with a crew of two, a pilot and an observer. It required the design to feature a
removeable centreline float, one that could easily be replaced with a fuselage mounted landing gear
for land-based operations, and it also required that the wings had to be able to be folded back
due to the deck and hangar space limitations aboard Battleships and Cruisers. All of this
had to be built within a weight limitation of 6350 pounds, however the most stringent and critical
part of the design specification was the engine. The Navy wanted to use a new, experimental, and
mostly unproven engine for their new scout. This was an air-cooled 12.7 litre inverted V-12 being
developed by Ranger. It boasted a very low fuel consumption, and this greatly interested the Navy,
as it meant they could increase the range of their scout planes without hampering their performance
by adding additional fuel tanks. Unfortunately, this engine would prove to be the equivalent
of an Achilles heel for the Curtiss Seamew, though of course they didn’t know it the time.
Curtiss submitted their design to the US Navy in August of 1937,
and in May of 1938 they were awarded a contract to produce a prototype that would be designated
the XSO3C-1; at the same time, Vought also received a contract to produce a prototype,
the XSO2U-1, and the two planes would be evaluated against each other.
In its original form, the Curtiss prototype could be considered fairly good looking.
Unlike its predecessor, the SOC Seagull, it was an all-metal design, ditching the fabric-covered
fuselage and wings for stressed aluminium panelling. Similar to other Curtiss monoplanes,
the wing leading edge was straight whereas the trailing edge tapered towards the wingtips.
The two most recognisable features were the engine’s exhaust stacks, which protruded out
from the bottom of the nose, and the flush line of the upper fuselage that ran from the
pilot’s cockpit all the way back to the tail. The prototype aircraft was complete by the Autumn
of 1939, being initially fitted with a fixed landing gear, and it flew for the first time
on the 6th of October. After this it went on to compete in a series of competitive trails against
the prototype submitted by Vought. Due to the strict requirements of the Naval specification,
both planes looked remarkably similar, and as such their performance figures were also very close.
Though the Vought design was 3 mph faster, it was also over 300 pounds heavier than the Curtiss,
and after due consideration after the trials the decision was made to go with the Curtiss
design. An initial production order of 300 units was placed, but before the
first aircraft even left the factory there were some worrying signs that not all would be well.
In March 1940, Curtiss gave the original prototype to the Navy for its final trials.
Cooling and stability problems plagued these trials from the outset, and indeed there had
been a few worrying signs in the earlier trials with both the Curtiss and Vought prototypes. Early
on in these final tests, the engine overheated so badly that it completely failed, causing the
prototype to sink in shallow water on the 21st of July 1941. Curtiss took it back to their
production facility at Buffalo for a rebuild, but the engine failed again later on in November.
Unwilling to produce 300 versions of an aircraft that a) suffered in lateral stability,
and b) had an engine that was so fragile it might as well have been a glider, Curtiss sent the
prototype to Langley Field to undergo a series of wind tunnel experiments to sort out the problems.
Based on their findings, Curtiss enlarged the air intake and added extra cowl flaps,
and while this didn’t completely solve the heating issue, it did reduce it to
the point that the engine wouldn’t try to explode if the pilot looked at the throttle.
The issue of stability was solved by a series of iterative changes that didn’t happen all at once,
but they ultimately resulted in the enlargement of the tail surfaces and rudder, the addition
of a dorsal fin section that ran above the aft cockpit, and the addition of upswept wing tips.
When the SO3C finally entered production, it was given the name Seamew by Curtiss, but the
US Navy named it the Seagull in 1941 - which was the same name as its predecessor. However,
despite being built later it was in fact the first to be given this name, as the US Navy
retroactively named the SOC as the Seagull when they were brought back into frontline service – an
embarrassing topic that we will covershortly. As a result of this, SO3C is both known as the
Seagull and Seamew, but I always refer to it as the Seamew to prevent unnecessary confusion.
It was built in three main variants, with a few single outliers. Of the initial production order
for 300 units, 141 would be completed as the SO3C-1, with the first of these aircraft being
delivered in July 1942. As a scout plane, its armament was light, a single forward
firing 30 calibre machine gun in the nose, and a rear-mounted 50 calibre machine gun for defence.
It also had a set of wing racks that allowed it to carry a pair of 100 lb bombs;
potentially, it could also have carried a pair of depth charges as well,
but I couldn’t find exact numbers on this for the first production model.
The second production model, the SO3C-2, definitely could carry depth charges though,
and they also came with a ventral bomb rack. The other main differences included the fitting of an
arrestor gear for carrier use, and the fitting of an uprated version of the Ranger engine
that now put out 520hp. Approximately 200 of these second versions were built,
making them the most numerous of the US models. After this, there were plans to build almost 700
of the SO3C-3, But very few of these last models were actually built as the aircraft
was being hastily withdrawn from service…due to it being somewhat of a colossal failure.
Though the heating and stability issues on the prototype had been fixed, once the production
Seamews entered service with US fleets, a myriad of other problems quickly became apparent.
The largest and most embarrassing of these was the inability of the Seamew to make a water
takeoff with a full fuel load. Now admittedly, this was only partly the fault of the aircraft,
as the Navy had stipulated increased fuel load requirements, but regardless of this it meant that
the Seamew could only take off from the water with less than half of its maximum fuel load
onboard…which for a scout plane that needed long range was hardly ideal
Along with that particular issue, two other problems arose that made it vastly unpopular with
the officers who had to fly it. Firstly, it was discovered that in rough water the central float
flexed so much that the propeller could actually strike it, this was unfortunate for several
reasons: it damaged the propeller, it damaged the float, and it terrified the pilot.
Secondly, the take-off attitude from the water was alarmingly steep, to the point where there
was a brief moment of time where the Seamew would have no aileron control, and the pilot
had to bring the tail up as fast as possible to maintain any control at all. This also meant that
if a problem occurred, or if a strong wind gust forced a stall, there was zero hope of recovery.
These problems, and a series of excessive operational accident quickly resulted in the early
withdrawal of the Seamew from service. It was then supplemented by the very plane it had been built
to replace, the SOC, which quickly took the Seamew’s Naval designation of Seagull for itself.
In the end, Seamew was such a failure that the average length of time that it was used on each
of its assigned ships was just about two months. Following this, the Navy tried to find use for
the Seamew as a radio controlled target tug, and these were redesignated as the SO3C-K. This didn’t
last long, as they lacked the engine power for this sort of role and they were rarely used.
A number of the SO3Cs, were ordered by the British Royal Navy under the terms of the
Lend-Lease, and these would officially be known as the Seamew -rather than the Seagull- when in
service with the Fleet Air Arm. These units were delivered with a fixed landing gear,
an arrestor hook, and a central bomb rack. However, like their American counterparts,
these planes were quickly disliked and discarded by British pilots, who referred to them as the
“sea-cow”, and most of the 250 aircraft delivered to the British ended up in Canada as target tugs.
There is a famous quote about the Seamew that came from a British pilot by the
name of Eleanor Lettice Curtis, and her words sum it up best – “it is hard to imagine how,
even in wartime, such an aircraft could have been accepted from the factory, let alone given
valuable cargo space across the Atlantic”. Harsh words Indeed. But, although it was a
failure, the Seamew shouldn’t be considered a failure of Curtiss itself. Rather it was
the failure of an experimental engine, the failure of overly strict naval specifications,
and then the failure of said Navy to comprehend the consequences of changing the specifications
after the aircraft had entered production. All of this would be proven by the Seamew’s replacement,
the Curtiss SC Seahawk, a plane that wasn’t hampered by design restrictions or an untested,
experimental engine. But that’s a story for another day.