Grumman Sabrecat Mk. II; "C-3M"/JZ931 of 800 NAS, FAA; Trimcomalee, May '45

Dizzyfugu · June 06, 2013, 06:55:13 AM

Now it's time to reveal one part of the truth...

With best regards to perttime, sturmvogel and PR19_kit!

1:72 Grumman Sabrecat Mk. II; aircraft "C-3M/JZ931 of 800 NAS, Royal Navy Fleet Air Arm; Trimcomalee, May 1945 (Whif/Kit conversion) by dizzyfugu, on Flickr

1:72 Grumman Sabrecat Mk. II; aircraft "C-3M/JZ931 of 800 NAS, Royal Navy Fleet Air Arm; Trimcomalee, May 1945 (Whif/Kit conversion) by dizzyfugu, on Flickr

Some background:
The so-called 'Sabrecat' was a special high performance derivate of Grumman's F8F Bearcat for the British Navy's Fleet Air Arm, tailored to the needs in the Pacific WWII theatre.

The original Bearcat concept began during a meeting between Battle of Midway veteran F4F Wildcat pilots and Grumman Vice President Jake Swirbul at Pearl Harbor on 23 June 1942. Lieutenant Commander Jimmie Thach emphasized one of his most important factors in fighters to Mr. Swirbul, "climb rate", which connoted "power." After intensively analyzing carrier warfare in the Pacific Theater of Operations for a year and a half, Grumman commenced designing the G-58 Bearcat.

1:72 Grumman Sabrecat Mk. II; aircraft "C-3M/JZ931 of 800 NAS, Royal Navy Fleet Air Arm; Trimcomalee, May 1945 (Whif/Kit conversion) by dizzyfugu, on Flickr

1:72 Grumman Sabrecat Mk. II; aircraft "C-3M/JZ931 of 800 NAS, Royal Navy Fleet Air Arm; Trimcomalee, May 1945 (Whif/Kit conversion) by dizzyfugu, on Flickr

Work on the Bearcat began in 1943 with the specifications calling for an aircraft able to operate from the smallest carrier, primarily in the interceptor role. The F6F's Pratt & Whitney R-2800 engine was retained, but compared to the Hellcat, the Bearcat was 20% lighter, had a 30% better rate of climb and was 50 mph (80 km/h) faster - it was, effectively, the smallest possible airframe mated with a strong and proven engine. Compared to the larger F6F, range was necessarily sacrificed, but rate of climb and agility were superior.

1:72 Grumman Sabrecat Mk. II; aircraft "C-3M/JZ931 of 800 NAS, Royal Navy Fleet Air Arm; Trimcomalee, May 1945 (Whif/Kit conversion) by dizzyfugu, on Flickr

The FAA had immediate interest in the type for its carriers in the Pacific, too, since such a fast and agile type was missing in the British arsenal. But the FAA demanded that the type would be adapted to British standards, and also carry a domestic engine - the powerful Napier Sabre had already been chosen. The Sabre was a very different engine, though: a H-24-cylinder, liquid cooled, sleeve valve, piston aero engine, designed by Major Frank Halford. It was a promising engine: in its early stages in 1938 it had been developing 2,200 hp (1,640 kW), and this should reach up to 3,500 hp (2,600 kW) in late-model prototypes.

1:72 Grumman Sabrecat Mk. II; aircraft "C-3M/JZ931 of 800 NAS, Royal Navy Fleet Air Arm; Trimcomalee, May 1945 (Whif/Kit conversion) by dizzyfugu, on Flickr

The Sabre engine necessitated a redesign of the complete Bearcat forward fuselage, though, including a large, chin-mounted radiator for the water-cooled engine. The oil coolers in the wing roots were retained. For the Sabrecat, a modified version of the Sabre III (intended for the stillborn Blackburn Firebrand naval fighter), the Sabre IIIA, was chosen. This engine was based on the Sabre IIA, but featured a revised ignition system with a maximum boost of 9 lbs and a Hobson fuel injection system. On the original Sabrecat, the Sabre IIIA drove a large, four-bladed Rotol propeller with a spinner. The Sabrecat's performance (considering rate of climb and top speed) was slightly better than the original F8F-1's, even though its range fell shorter.

1:72 Grumman Sabrecat Mk. II; aircraft "C-3M/JZ931 of 800 NAS, Royal Navy Fleet Air Arm; Trimcomalee, May 1945 (Whif/Kit conversion) by dizzyfugu, on Flickr

1:72 Grumman Sabrecat Mk. II; aircraft "C-3M/JZ931 of 800 NAS, Royal Navy Fleet Air Arm; Trimcomalee, May 1945 (Whif/Kit conversion) by dizzyfugu, on Flickr

From the start, many equipment pieces were replaced by equivalents of British origin, including the armament. This comprised four 20mm Hispano cannons and various external stores unter the wings, inclusing drop tanks, bombs of up to 1.000 lb calibre or six unguided air-to-ground rockets. Other differences to the Bearcat were not so obvious, e. g. the lack of the F8F's unique detachable wingtip system (if the "g"-force exceeded 7.5 "g", then the tips would snap off, leaving a perfectly flyable aircraft still capable of carrier landing).

The first F8F prototype for the US Navy flew on 31 August 1944, and the first Sabrecat only three months later, on 1 December 1944. Development was rather quick, since many improvements of the F8F were immediately integrated into the Sabrecat's design.

The first production aircraft for both USN and FAA were delivered in February 1945, and the Sabrecats were immediately thrown into service - now designated Sabrecat Mk. I and initially based on the carrier HMS Indomitable, serving alongside FAA F6F and F4U fighters.

1:72 Grumman Sabrecat Mk. II; aircraft "C-3M/JZ931 of 800 NAS, Royal Navy Fleet Air Arm; Trimcomalee, May 1945 (Whif/Kit conversion) by dizzyfugu, on Flickr

One specific flaw of early Sabrecats turned out to be its poor directional stability, caused by the draggy chin radiator. An enlarged/higher tail fin solved the problem (this fin was later incorporated into the USN's improved F8F-2) at high speeds, and this detail was changed after only 20 aircraft had been built. Nevertheless, the large propeller of the Mk. I Sabrecats caused considerably handling trouble at low speeds and made starting and landing on carrier decks more than hazardous.
Since the already nose-heavy and short aircraft precluded the use of a contra-rotating propeller, trials with a 5-bladed propeller of smaller diameter were hastily undertaken, and this eventually lead to, after only 35 produced Mk. I Sabrecats, the modified Mk. II, which served in parallel.

1:72 Grumman Sabrecat Mk. II; aircraft "C-3M/JZ931 of 800 NAS, Royal Navy Fleet Air Arm; Trimcomalee, May 1945 (Whif/Kit conversion) by dizzyfugu, on Flickr

At this time, the WWII hostilities were already coming to an end. Only 16 Mk. II Sabrecats were eventually built and delivered to the FAA until May 1945, and these were only used for about seven weeks - mostly from land bases, and as fighter bombers against ships and ground targets.

After the hostilities ceased, all Sabrecats were quickly withdrawn from service, since other types offered more versatility and even better performance.

1:72 Grumman Sabrecat Mk. II; aircraft "C-3M/JZ931 of 800 NAS, Royal Navy Fleet Air Arm; Trimcomalee, May 1945 (Whif/Kit conversion) by dizzyfugu, on Flickr

General characteristics
Crew: 1 pilot
Length: 30 ft 4.5 in (9.28 m)
Wingspan: 35 ft 10 in (10.92 m)
Height: 13 ft 9 in (4.21 m)
Wing area: 244 ft²[42] (22.67 m²)
Empty weight: 7,070 lb (3,207 kg)
Loaded weight: 9,600 lb (4,354 kg)
Max. takeoff weight: 12,947 lb (5,873 kg)
Powerplant: 1× Napier Sabre IIIA 24 cylinder H-engine, 2.300 hp (1.691 kW)

Performance:
Maximum speed: 447 mph (720 km/h) at 18,000 ft (5,500 m)
Range: 700 mi (1.127 km) with internal fuel; 1.040 mi (1.675 km) with two 90 gal drop tanks
Service ceiling: 36,500 ft (11,125 m)
Rate of climb: 4,700 ft/min (23.9 m/s)
Wing loading: 66.7 lb/ft² (192.1 kg/m²)
Power/mass: 0.22 hp/lb (360 W/kg)

Armament:
4× 20 mm Hispano Mk II cannon
6× 3 in (76.2 mm) RP-3 unguided air-to-ground rockets; alternatively, 6× 250 lb (113.5 kg), 2× 500 lb (227 kg) or 2× 1,000 lb (454 kg) bombs could be carried, or 2× 45 gal (205 l) or 90 gal (409 l) drop tanks.

1:72 Grumman Sabrecat Mk. II; aircraft "C-3M/JZ931 of 800 NAS, Royal Navy Fleet Air Arm; Trimcomalee, May 1945 (Whif/Kit conversion) by dizzyfugu, on Flickr

The kit and its assembly:
This model was inspired by events at whatifmodelers.com: a while back, fellow user perttime requested sturmvogel to do a profile of a Sabre-engined Bearcat, and he produced a colorful sketch/side view of a pylon racer. This motivated another modeler, PR19_kit, to produce an actual model of this aircraft - mating a vintage F8F-1 from FROG with the engine of a Heller Tempest M. II.

When pics of this ongoing project were posted (esp. with the plan take give this creation called the "Sabrecat" an all-blue FAA livery), I was in for this idea and decided to contribute another interpretation of the original idea. Complicated, but credit to those who deserve it!

More about this multi-modeler project can be found here: <a href="http://www.whatifmodelers.com/index.php/topic,37051.0.html" rel="nofollow">www.whatifmodelers.com/index.php/topic,37051.0.html</a>

Anyway, the interesting twist to the story and the respective model of mine is that it actually consists of totally different parts than PR19_Kit's. I had a Matchbox Tempest in store, which would donate its optional Sabre nose, and for the rest I decided to give the relatively new mixed media kit of a late F8F-2 from Art Model (from Russia) a try.

1:72 Grumman Sabrecat Mk. II (Whif/Kit conversion) - WiP by dizzyfugu, on Flickr

1:72 Grumman Sabrecat Mk. II (Whif/Kit conversion) - WiP by dizzyfugu, on Flickr

The Art Model kit is ambiguous. It's a short-run kit in styrene and comes with many resin parts, which are finely molded: the cockpit tub with side panel and a dash board, a very fine landing gear wells interior which includes any kind of tubes and air ducts, delicate wheels and four unguided missiles, as well as the complete engine block. The styrene parts have very fine recessed panel lines, the injected canopy is clear and relatively thin - it looks promising.

1:72 Grumman Sabrecat Mk. II; aircraft "C-3M/JZ931 of 800 NAS, Royal Navy Fleet Air Arm; Trimcomalee, May 1945 (Whif/Kit conversion) by dizzyfugu, on Flickr

1:72 Grumman Sabrecat Mk. II (Whif/Kit conversion) - WiP by dizzyfugu, on Flickr

But when you work on it... it's challenging. Biggest drawback is that (at least with my specimen) the resin cockpit and landing gear interior were both much too wide - neither the fuselage halves would 'close', and between the upper and lower wing halves a 1.5mm gap was left. It took some serious sanding and shaving on the delicate and brittle resin parts to make them fit. The wing interior was especially difficult to handle. It's really only something for advanced modelers!

1:72 Grumman Sabrecat Mk. II (Whif/Kit conversion) - WiP by dizzyfugu, on Flickr

1:72 Grumman Sabrecat Mk. II (Whif/Kit conversion) - WiP by dizzyfugu, on Flickr

But back to the conversion: In order to fit the Sabre engine with its chin radiator, I cut off the original nose of the Bearcat, behind the wings' leading edge. Melding the parts was not as complicated as expected - in my case, both diameter and shape differences between Tempest and Bearcat were small enough that I could just use NC putty. But it still took five turns of sculpting and sanding until I got a coherent shape... AFAIK, PR19_Kit's FROG/Heller "Sabrecat" needed the engine part to be widened considerably!

A major change/addition was a new propeller. I thought that the original, four-bladed Tempest propeller with its HUGE diameter would not really be suited for a carrier-based aircraft, even though the stalky Bearcat landing gear would make its use possible. Anyway, I wanted a smaller, five-bladed propeller, and this was created through the original Tempest spinner, "filled" with 2C putty, and five separate, deep propeller blades from a Griffon-powered Spitfire (aftermarket parts from Pavla) attached to it. THIS looks odd, but... why not!? This is whifworld, after all.

Beyond the new parts, a styrene tube was implanted into the front end, so that, with a new, long axis, the propeller could spin freely for beauty pics (and ease of construction of the rest of the kit).

1:72 Grumman Sabrecat Mk. II (Whif/Kit conversion) - WiP by dizzyfugu, on Flickr

1:72 Grumman Sabrecat Mk. II; aircraft "C-3M/JZ931 of 800 NAS, Royal Navy Fleet Air Arm; Trimcomalee, May 1945 (Whif/Kit conversion) by dizzyfugu, on Flickr

The rest of the Bearcat was taken OOB, including the very nice landing gear with its resin wheels. A pilot was added, and the external ordnance was changed: instead of HVARs of American origin my Sabrecat in FAA use (see below) received four unguided rockets of British origin, plus two small iron bombs (250 lb/113 kg caliber). The optional underbelly drop tank was omitted.
Another addition with some British flavor are four long-barreled Hispano 20mm cannons on the wings. They actually belong to a Hurricane Mk. IIC, but I deemed them appropriate for this beefy, compact fighter.

Painting and markings:
Since an all-blue Sabrecat was already under development in parallel I decided to go for a Fleet Air Arm aircraft as well, but in the classic Temperate Sea Scheme in Dark Sea Grey/Dark Slate Grey/Sky, with late-war roundels and some flashy white ID stripes. Inspiration (and decals) came from an Xtradecal sheet (#72142 'Yanks with Roundels - US Aircraft in the FAA, Pt. 3'), from which I mixed the paint scheme and markings of two FAA Grumman Hellcats from the Pacific theatre in 1945.

1:72 Grumman Sabrecat Mk. II (Whif/Kit conversion) - WiP by dizzyfugu, on Flickr

1:72 Grumman Sabrecat Mk. II (Whif/Kit conversion) - WiP by dizzyfugu, on Flickr

Painting was straightforward, using a pattern from an FAA Wildcat as benchmark. The basic tones were Humbrol 27 and 224, and this was weathered with Dark Sea Grey and Dark Slate Grey from Testors from their Authentic line. The lower side was painted with Humbrol 90 and treated with Sky from Testors. A wash with black ink emphasized the fine panel lines and engravings.

The cockpit interior was painted with Humbrol 150 (Cockpit Green) and received some dry-brushing with bright Zinc Chromate Green from Testors. The landing gear interior received a yellow-ish primer color: I used Humbrol 225 (Mid-Stone) as a basis and added some dry-brushing with Humbrol 93 (Sand). The metal parts were painted in simple Humbrol 56 (Aluminum).

The white ID stripes are actually all decals - these were cut from an all-white sheet from TL Modellbau. Only the propeller spinner was painted, in a mix of white and light grey, so that it would not look too bright.

After decal application I added some fake panel lines on the fuselage with Tamiya "Smoke", a translucent, greyish paint, and after some soot stains were painted around the guns and exhaust pipes, everything was sealed under a matt varnish coat.

I was sceptical at first, but the odd roundels and the white ID stripes really make the Sabrecat look interesting!

1:72 Grumman Sabrecat Mk. II; aircraft "C-3M/JZ931 of 800 NAS, Royal Navy Fleet Air Arm; Trimcomalee, May 1945 (Whif/Kit conversion) by dizzyfugu, on Flickr

All in all, an interesting project which made it to the hardware stage in maybe 10 days - quicker than expected. But I was lucky to have all ingredients in store when I started working. And now I am looking forward to its blue sister, a Mk.I from PR19_kit!

NARSES2 · June 06, 2013, 07:12:42 AM

Oh that is just stupendous

Dizzyfugu · June 06, 2013, 07:39:10 AM

Thank you!

Lots of pics, I know, but since PR19_kit had so much trouble with his conversion, I also took and provided some more WiP documents from my build than usual, for reference.

perttime · June 06, 2013, 09:38:30 AM

Most excellent

sturmvogel · June 06, 2013, 11:47:57 AM

It looks absolutely spectacular and the backstory is perfect. If only this could be entered in the Whiffies.

andrewj · June 06, 2013, 12:28:47 PM

Nice , great model ,but I wouldn't like to make a forced landing at sea with that big chin intake.

Andrew

Father Ennis · June 06, 2013, 12:48:36 PM

Great job and background ,too. Fantastic build. It's just goes to show, two different people making the same build but giving their own interpretations. A very rare experience,indeed.

But, I still think it looks like a short fat Typhoon ... !!! LOL !!!

Ian the Kiwi Herder · June 06, 2013, 01:12:59 PM

Lots of good work here. Well done for seeing it through. My only 'issue' would be the weathering - I appreciate that Naval aircraft do get more than their fare share exposure to the elements, but to me it looks a wee bit 'heavy handed' here.

Not a criticism, just an observation. Another observation... your getting better with each build you show us.

Ian

Dizzyfugu · June 06, 2013, 11:54:24 PM

Quote from: andrewj on June 06, 2013, 12:28:47 PM
Nice , great model ,but I wouldn't like to make a forced landing at sea with that big chin intake.

Andrew

You would even LESS want to that with the original Tempest propeller... wait for PR19_kit's "original" Mk. I version, which is to feature that!

Besides, many thanks to everyone for the feedback, highly appreciated!

Dizzyfugu · June 06, 2013, 11:58:27 PM

Quote from: Ian the Kiwi Herder on June 06, 2013, 01:12:59 PM
Lots of good work here. Well done for seeing it through. My only 'issue' would be the weathering - I appreciate that Naval aircraft do get more than their fare share exposure to the elements, but to me it looks a wee bit 'heavy handed' here.

Not a criticism, just an observation. Another observation... your getting better with each build you show us.

Ian

I know what you mean, and I do not see it as criticism. I do everything with brushes and enamels, so weathering or shading a 1:72 vehicle can easily look a bit shabby, esp. when you watch the result on a relatively big picture. On the Sabrecat, the contrast between the upper colors in themselves is a bit harsh, totally agree, but I kept the result because it made the aircraft look less uniform. It's "my style", and observers can like it - or not. I am fine with it, otherwise I would not have shown it...

PR19_Kit · June 07, 2013, 01:24:45 AM

It's weird that the two ways of building a Sabrecat have such differences in their source kits.

My combination needed LOTS of work to get the narrow Sabre engine from the Heller Tempest to match the wide fuselage of the Frog Bearcat. Dizzy's looks like it fitted right on there!

I'll compare my setup with an ex-Mongram F8F and see how that differs.

Dizzyfugu · June 07, 2013, 02:38:07 AM

Quote from: PR19_Kit on June 07, 2013, 01:24:45 AM
Dizzy's looks like it fitted right on there!

No, certainly not... One potential reason could be that the fuselage halves tended to "overlap" when they had to be presses into the wing part, which fits VERY tightly on this kit. I assume that this "pressed" the Bearcat front end together, and this made the intersection less hazardous. When you look at the cockpit close-up of the finished kit you can see how asymmetrical the area in front of the cockpit is - even the windshield did not fit anymore and it has a slight deviation... Well, that's whiffing - you NEVER know how things turn out!

NARSES2 · June 07, 2013, 07:20:20 AM

Quote from: sturmvogel on June 06, 2013, 11:47:57 AM
It looks absolutely spectacular and the backstory is perfect. If only this could be entered in the Whiffies.

It's in the nominations for the next Wiffies

Dizzyfugu · June 07, 2013, 07:30:56 AM

I've seen that - actually, that nomination would have to include a LOT of people who took part in this mini group build?
Thanks a lot, anyway - I am looking forward for PR19_kit's "version" of things...

Tophe · June 07, 2013, 08:57:24 AM

Congratulations also!