In my previous article on the P-51 “Sea Horse” I talked about how the US Navy, though swearing off liquid-cooled inline engines in 1921, did keep a close eye on development on those types of powerplant. In the late 1930’s, there looked to be a few prospects that seemed promising enough that the Navy planners thought they might be worth putting some investment into. Amongst these was the Lycoming XH-2470.
Like many other aero engine manufacturers of the 1930s, Lycoming was scrambling to stay ahead of the competition as aircraft engines became increasingly powerful in that decade. In 1933 Lycoming had begun work on an engine, designated as the O-1230, that looked to be what today we might describe as a “disruptive” technology; a 12-cylinder liquid cooled engine that produced 1,200hp. What made this new engine special was that in contrast to most rival designs, the O-1230 was a horizontally opposed – or ‘flat’ – design that made it potentially more aerodynamic, especially if mounted in an aircraft’s wings.
In fact, despite considerable investment in the development by the United States Army Air Corp (USAAC) the engine was problematic and abandoned. But Lycoming weren’t about to give up completely with the concept and so in 1938 they began work on a design that coupled two of the O-1230’s together to form a 24-cylinder H-Block type that would theoretically produce 2,300hp; the Lycoming XH-2470. This was potentially a huge deal in the late 1930’s for future military aircraft and both the USAAC and the United States Navy invested in the new powerplants development.
The US Navy had only just started to receive the first of their new Brewster F2 fighters into service, as well as placing orders for the Grumman F4F, but they were already planning on the next generation of fighters for their carrier fleet and the new hugely powerful engine – which produced almost twice the horsepower of the F4F’s Twin Wasp radial – seemed like an excellent prospect.
On the 30th June 1941, the Navy placed orders for their next generation of naval fighters; the F6F Hellcat and the F7F Tigercat twin-engine heavy fighter. What isn’t so well remembered was that they also ordered a third aircraft; a formidable new naval interceptor that, in a break from their avowed tradition, would use the new liquid-cooled engine that they had invested in.
The Curtiss XF14C.
(Now, I shall say right away that all of the pictures of the XF14C you see in this piece are of the later XF14C-2 model because the Lycoming 24-cylinder engine never worked out. To be fair to Lycoming, coupling engines like this was an idea that basically every major aircraft producing country at the time was giving serious consideration to the concept to create H-and-X-block engines.)
Of all-metal construction and equipped with folding wings, the XF14C was planned to have six 0.5-calibre Browning heavy machine guns in the wings as armament, which was later changed to four 20mm cannon. This might all seem pretty conventional, but the chosen propellor was not as the idea was to fit a contra-rotating prop on the aircraft.
Curtiss projections were that the aircraft would have a top speed of 374mph (602km/h) with an initial climb rate of 2,810 fpm (14.3 m/s), but the Navy’s own wind tunnel tests of the design led them to conclude that Curtiss was being somewhat optimistic with their assessments.
Regardless, things progressed until October 1943 when, with the first of the two ordered prototypes just about finished, the unavoidable problem arose in the fact that the Lycoming engine was not actually available for fitting on the aircraft. After a couple of months of wrangling the Navy dumped the Lycoming H-block and decided to fit a radial engine that was in keeping with their general philosophy on naval aircraft powerplants instead.
Having said that the engine they chose was certainly a beast; a turbo supercharged variant of the Wright R-3350 Duplex Cyclone – the engine famously used on the B-29 Superfortress.
This engine, though bulkier than the Lycoming, could produce 2,250hp and was ideally suited for high-altitude combat, leading the Navy to decide that the new aircraft, now designated as the XF14C-2, might make a high-altitude fighter.
To be honest, it seems that the Navy was just double checking that they weren’t missing out on something outstanding, because by this point the F6F Hellcat, which remember had been ordered at the same time as the XF14C, was carving its legend across the skies of the Pacific as one of the great carrier fighters.
The XF14C, however, was never going to be that. Curtiss were able to make the necessary changes reasonably quickly, and the XF14C-2 was even fitted with contra-rotating propellors. But when it was handed over to the Navy for flight tests in September 1944 it proved to be rather disappointing.
Top recorded speed was 398mph (641 km/h) at 32,000 ft (9,754 m), which wasn’t anything special considering the other aircraft in development at the time. Additionally, the propellor system caused the aircraft to shudder to an alarming degree.
This late in the war the US Navy was of the opinion that they no longer needed a high-altitude fighter and that their existing designs, as well as the newer ones that were coming into service imminently, were more than sufficient for their needs. So, they cancelled the XF14C.
Curtiss launched another proposal for an XF14C-3 which would have had a pressurized cockpit and the ability (allegedly) of being able to operate at up to 40,000 feet (c.12,200m). The Navy paid for studies to be carried out on this until early 1945, but soon concluded once again that they had no need for this type and pulled the plug completely on the project, leaving the one and only XF14C-2 to head for the scrapyard.
And that would be that except for the fact that this aircraft, along with the XP-60, were the last piston engine fighters built by Curtiss, a company that had been at the cutting edge of aviation development from the earliest days of the aeroplane.
In fact, the XF14C represents the sort of issues that had been besetting Curtiss since the 1930s. The company was struggling to stay innovative, especially in comparison to other companies like North American and Bell, plus it is arguable that the company was a victim of its own success in that it ended up with far more work than it could comfortably handle during the war, leading to issues in quality control and development. And where it had tried to innovate, which in the case of the XF14C was represented in betting on a novel powerplant and propellor system, that gamble ultimately proved to be a poor one.
As a result, the end of the war saw Curtiss, despite being ranked second in terms of the value of contracts awarded to it during the conflict, rapidly fall by the wayside, with the company leaving aircraft production completely in 1948 and the XF14C an almost completely forgotten aircraft.
Sources/Related:
https://en.wikipedia.org/wiki/Curtiss_XF14C
https://oldmachinepress.com/2020/02/20/curtiss-xf14c-carrier-based-fighter/
https://tailhookdaily.typepad.com/tailhook_daily_briefing/2007/07/flightdeck-frid.html
https://oldmachinepress.com/2018/05/05/lycoming-xh-2470-24-cylinder-aircraft-engine/
North American ETF-51D; The “Sea Horse”
The XP-47H; Shark-Nosed Thunderbolt
“Super Corsair” – The Goodyear F2G
Supermarine Seafire; The Great British Bodge Job
