DONE +++ Grumman G-79B/F9F-1 "JetCat"

Dizzyfugu · April 21, 2018, 02:58:08 AM

Well, after finding out that there were two of the four (real world) Grumman G-79 desings that disturbingly resemble my Gudkov Gu-1 build for this GB, I decided to add an American mixed-powerplant counterpart, the G-79B. This one will carry a turboprop, though, instead of an R-2800 radial (the G-79A), but again a tailsitter with a jet booster in its tail.

An Academy P-47D will once more be the "core", but there will be donor parts from a Grumman Panther instead of the classic Novo Attacker, in order to stress the family relationship.

Stay tuned.

Dizzyfugu · April 22, 2018, 11:34:59 AM

Just FYI, here's a scan of the Grumman G-79B's profile:

Grumman G-79B by dizzyfugu, on Flickr

Dizzyfugu · April 26, 2018, 12:27:28 AM

Already massive progress here (it's already all-blue!), but due to a very busy weekend and jod assignment during the past days, no pics from the G-79B (yet).

Dizzyfugu · April 28, 2018, 10:54:10 AM

The JetCat has been more or less finished today, but pics are still pending...

Dizzyfugu · April 29, 2018, 01:44:07 AM

Here we go, with some delay!

This is submission to the Cold War GB was a rather spontaneous idea. It was actually spawned after I finished my fictional Gudkov Gu-1 mixed propulsion fighter - while building (using the engine front from an F6F Hellcat) I had the impression that it could also have ended up as a post-war USN fighter design...?

A couple of days later, while browsing literature for inspiration, I came across Grumman's G-79 series of designs that eventually led to the F9F Panther - and I was amazed that the 'A' design almost looked like my kitbashed Soviet fighter!

So I considered a repeated build of a P-47D/Supermarine Attacker kitbash, just in American colors. But with the F9F relationship, I planned the integration of Panther parts, so that the new creation would look different from the Gu-1, but also show some (more) similarity to the Panther.

The plan appeared feasible. Again, the aircraft's core is an Academy P-47D, with its outer wings cut off. Cockpit and landing gear were retained. However, instead of Supermarine Attacker wings from a Novo kit, I attached F9F-2 wings from a Hasegawa kit. Shape-wise this worked fine, but the Panther wings are much thinner than the Thunderbolt's, so that I had to integrate spacers inside of the intersections which deepen the Hasegawa parts. Not perfect, but since the type would feature folding wings, the difference and improvisation is not too obvious.

1:72 Grumman G-79B/F9F-1 "JetCat"; aircraft "307/S" of the US Navy VF-53 "Iron Angels" on board of USS Kearsarge; Korea, 1952 (Whif/Kitbashing) - WiP by dizzyfugu, on Flickr

1:72 Grumman G-79B/F9F-1 "JetCat"; aircraft "307/S" of the US Navy VF-53 "Iron Angels" on board of USS Kearsarge; Korea, 1952 (Whif/Kitbashing) - WiP by dizzyfugu, on Flickr

On the fuselage, the Thunderbolt's air outlets on its flanks were faired over and most of the tail section cut away. In the lower part of the tail, a jet pipe (from a Heller F-84G) was added and blended with PSR into the Thunderbolt fuselage, similar to the Gu-1. In order to blend the new engine with the fuselage and come close to the G-79B's vaguely triangular fuselage diameter, the P-47's deep belly was cut away, faired over with styrene sheet, and everything blended into each other with more PSR work.

A completely new fin was scratched from an outer wing section from a Heinkel He 189, in an attempt to copy the G-79B's shape according to the drawing I used as benchmark for the build. I also used the F9F's stabilizers. With clipped tips they match well in size and shape, and add to the intended Grumman family look. The original tail wheel well was retained, but the tail wheel was placed as far back as possible and replaced by the twin wheel from a Hasegawa F5U. The Panther's OOB tail hook was integrated under the jet pipe, too.

The front section is completely different and new, and my choice fell on the turboprop-powered G-79B because I did not want to copy the Gu-1 with its radial engine. However, the new turboprop nose was not less complicated to build. Its basis is a 1:100 engine and contraprop from a VEB Plasticart Tu-20/95 bomber, a frequent ingredient in my builds because it works so well in 1:72 scale. This slender core was attached to the Thunderbolt's fuselage, and around this basis a new cowling was built up with 2C putty, once more in an attempt to mimic the original G-79B design as good as possible.

1:72 Grumman G-79B/F9F-1 "JetCat"; aircraft "307/S" of the US Navy VF-53 "Iron Angels" on board of USS Kearsarge; Korea, 1952 (Whif/Kitbashing) - WiP by dizzyfugu, on Flickr

1:72 Grumman G-79B/F9F-1 "JetCat"; aircraft "307/S" of the US Navy VF-53 "Iron Angels" on board of USS Kearsarge; Korea, 1952 (Whif/Kitbashing) - WiP by dizzyfugu, on Flickr

As a final step, two exhaust pipes were mounted to the lower fuselage in front of the wings' leading edge.

The air intakes for the jet booster are actually segments from a Sopwith Triplane fuselage (Revell) – an unlikely source, but the shape of the parts was just perfect. More PSR was necessary to blend them into the aircraft's flanks, though.

1:72 Grumman G-79B/F9F-1 "JetCat"; aircraft "307/S" of the US Navy VF-53 "Iron Angels" on board of USS Kearsarge; Korea, 1952 (Whif/Kitbashing) - WiP by dizzyfugu, on Flickr

PR19_Kit · April 29, 2018, 09:15:23 AM

That's a tour de force if ever I saw one Thomas. LOVE the idea of using Sopwith Camel parts on a Whiffed 1940s mixed power aircraft.

Doug K · April 29, 2018, 09:49:48 AM

Fantastic, the second image looks like a Wyvern...... sort of!

Dizzyfugu · April 29, 2018, 11:40:05 PM

Well, if you have a vision, either consult the doctor or go with the flow...

Having a benchmark for the design is helpful, but sometimes it's hard to recreate the details. The air intakes caused some serious headaches - while the Gu-1 was a "free" creation, this one is more or less based on a real design, and it took some time to come up with the Triplane fuselage...

Bet everything blends together well. Even the contraprop "works", both props spin!

Besides, here's an update concerning the paint job: As per usual, I'd rather go with conservative markings on a fictional aircraft. Matching the Korean War era, the aircraft became all-over FS 35042 (Modelmaster). A black ink wash emphasized the partly re-engraved panel lines, and some post shading highlighted panels.

1:72 Grumman G-79B/F9F-1 "JetCat"; aircraft "307/S" of the US Navy VF-53 "Iron Angels" on board of USS Kearsarge; Korea, 1952 (Whif/Kitbashing) - WiP by dizzyfugu, on Flickr

1:72 Grumman G-79B/F9F-1 "JetCat"; aircraft "307/S" of the US Navy VF-53 "Iron Angels" on board of USS Kearsarge; Korea, 1952 (Whif/Kitbashing) - WiP by dizzyfugu, on Flickr

The wings' leading edges and the turboprop's intake were painted with aluminum, similar edges on fin and stabilizers were created with silver decal material. The interior of cockpit and landing gear was painted with green chromate primer.

The markings were puzzled together. "Stars and Bars" and VF-53 markings were taken from a Hobby Boss F4U-4 kit. The blue fin tip is the marking for the 3rd squadron, so that the "307" tactical code is plausible, too (the latter comes from a Hobby Boss F9F-2). In order to keep things subtle and more business-like (after all, the aircraft is supposed to be operated during the ongoing Korean War), I did not carry the bright squadron color to any other position like the spinner or the wing tips.

1:72 Grumman G-79B/F9F-1 "JetCat"; aircraft "307/S" of the US Navy VF-53 "Iron Angels" on board of USS Kearsarge; Korea, 1952 (Whif/Kitbashing) - WiP by dizzyfugu, on Flickr

1:72 Grumman G-79B/F9F-1 "JetCat"; aircraft "307/S" of the US Navy VF-53 "Iron Angels" on board of USS Kearsarge; Korea, 1952 (Whif/Kitbashing) - WiP by dizzyfugu, on Flickr

After some final detail work and gun and exhaust soot stains, the kit was sealed with semi-gloss acrylic varnish (Italeri). Matt acrylic varnish was used for weathering effects, so that the aircraft would not look too clean and shiny.

With the paint, it's amazing how sleek and conclusive this big thing looks. My biggest fears were the wings, because the outer (Panther) parts were so thin. But the PSR effort was successful, you can hardly tell the implant scars - and, moreover, you hardly suspect that there's a Thunderbolt at the heart of it!?

Beauty pics and background story to follow soon.

NARSES2 · April 30, 2018, 07:38:29 AM

It's is looking good, that's for sure

PR19_Kit · April 30, 2018, 10:11:24 AM

Quote from: Dizzyfugu on April 29, 2018, 11:40:05 PM

- and, moreover, you hardly suspect that there's a Thunderbolt at the heart of it!?

THAT'S for sure!

Dizzyfugu · May 01, 2018, 11:55:46 PM

1:72 Grumman G-79B/F9F-1 "JetCat"; aircraft "307/S" of the US Navy VF-53 "Iron Angels" on board of USS Kearsarge; Korea, 1952 (Whif/Kitbashing) by dizzyfugu, on Flickr

Some background:
Development studies at Grumman for jet-powered fighter aircraft began near the end of World War II as the first jet engines emerged. In a competition for a jet-powered night fighter for the United States Navy, on 3 April 1946 the Douglas F3D Skyknight was selected over Grumman's G-75, a two-seater powered by four Westinghouse J30s. The Navy's Bureau of Aeronautics (BuAer) also issued a contract to Grumman for two G-75 prototype aircraft on 11 April 1946, in case the Skyknight ran into problems.

However, Grumman soon realized that the G-75 was a dead end. But the company had been working on a completely different day fighter, the G-79, which offered a higher potential. In order to keep Grumman in the US Navy's procurement loop, BuAer, in a bureaucratic maneuver, did not cancel the G-75 contract, but changed the wording to include prototypes of the entirely different G-79, too.

The G-79 project comprised a total of four different layouts and engine arrangements for a single seat fighter aircraft. G-79A and B were traditional tail sitters, but both featured mixed propulsion for an enhanced performance: G-79A was powered by an R-2800 radial engine and a Rolls Royce Derwent VI jet booster in the tail, fed by a pair of dorsal air intakes behind the cockpit. The G-79B was a similar aircraft, but its primary engine was a General Electric TG-100 turboprop in a more slender nose section. Even though both designs were big aircraft, initial calculations indicated a performance that would be superior to the Grumman F8F Bearcat, which had been designed as a thoroughbred interceptor.

The other two designs were pure jet fighters, both with a tricycle landing gear. G-79C had a layout reminiscent of the Gloster Meteor and was powered by two Derwent VI engines in bulky wing nacelles, and G-79D was finally an overall smaller and lighter aircraft, similar in its outlines to the early Vought F6U Pirate, and powered by a single Nene in the rear fuselage, fed by air intakes in the wing roots.

1:72 Grumman G-79B/F9F-1 "JetCat"; aircraft "307/S" of the US Navy VF-53 "Iron Angels" on board of USS Kearsarge; Korea, 1952 (Whif/Kitbashing) by dizzyfugu, on Flickr

1:72 Grumman G-79B/F9F-1 "JetCat"; aircraft "307/S" of the US Navy VF-53 "Iron Angels" on board of USS Kearsarge; Korea, 1952 (Whif/Kitbashing) by dizzyfugu, on Flickr

1:72 Grumman G-79B/F9F-1 "JetCat"; aircraft "307/S" of the US Navy VF-53 "Iron Angels" on board of USS Kearsarge; Korea, 1952 (Whif/Kitbashing) by dizzyfugu, on Flickr

Since the operation of jet-powered aircraft from carriers was terra incognita for the US Navy, and early turbojets thirsty and slow to react to throttle input, BuAer decided to develop two of Grumman's G-79 designs into prototypes for real life evaluation: one of the conservative designs, as a kind of safe route, and one of the more modern jets.
From the mixed propulsion designs, the turboprop-powered G-79B was chosen (becoming the XF9F-1 'JetCat'), since it was expected to offer a higher performance and development potential than the radial-powered 'A'. From the pure jet designs the G-79D was chosen, because of its simplicity and compact size, and designated XF9F-2 'Panther'.

The first JetCat prototype made its maiden flight on 26 October 1947, but it was only a short airfield circuit since the TG-100 turpoprop failed to deliver full power and the jet booster had not been installed yet. The prototype Panther, piloted by test pilot Corky Meyer, first flew on 21 November 1947 without major problems.

In the wake of the two aircrafts' test program, several modifications and improvements were made. This included an equal armament of four 20mm guns (mounted in the outer, foldable wings on the JetCat and, respectively, in the Panther's nose). Furthermore, both aircraft were soon armed with underwing HVAR air-to-ground rockets and bombs, and the JetCat even received an underfuselage pylon for the potential carriage of an airborne torpedo. Since there was insufficient space within the foldable wings and the fuselage in both aircraft for the thirsty jet's fuel, permanently mounted wingtip fuel tanks were added on both aircraft, which incidentally improved the fighters' rate of roll. Both F9F types were cleared for flight from aircraft carriers in September 1949.

1:72 Grumman G-79B/F9F-1 "JetCat"; aircraft "307/S" of the US Navy VF-53 "Iron Angels" on board of USS Kearsarge; Korea, 1952 (Whif/Kitbashing) by dizzyfugu, on Flickr

1:72 Grumman G-79B/F9F-1 "JetCat"; aircraft "307/S" of the US Navy VF-53 "Iron Angels" on board of USS Kearsarge; Korea, 1952 (Whif/Kitbashing) by dizzyfugu, on Flickr

1:72 Grumman G-79B/F9F-1 "JetCat"; aircraft "307/S" of the US Navy VF-53 "Iron Angels" on board of USS Kearsarge; Korea, 1952 (Whif/Kitbashing) by dizzyfugu, on Flickr

The F9F-1 was soon re-engined with an Allison T38 turboprop, which was much more reliable than the TF-100 (in the meantime re-designated XT31) and delivered a slightly higher power output. Another change was made for the booster: the bulky Derwent VI engine from the prototype stage was replaced by a much more compact Westinghouse J34 turbojet, which not only delivered slightly more thrust, it also used up much less internal space which was used for radio and navigation equipment, a life raft and a relocated oil tank. Due to a resulting CG shift towards the nose, the fuselage fuel cell layout had to be revised. As a consequence, the cockpit was moved 3' backwards, slightly impairing the pilot's field of view, but it was still superior to the contemporary Vought F4U.

Despite the engine improvements, though, the F9F-1 attained markedly less top speed than the F9F-2. On the other side, it had a better rate of climb and slow speed handling characteristics, could carry more ordnance and offered a considerably bigger range and extended loiter time. The F9F-2 was more agile, though, and more of the nimble dogfighter the US Navy was originally looking for. Its simplicity with just a single engine was appealing, too.

1:72 Grumman G-79B/F9F-1 "JetCat"; aircraft "307/S" of the US Navy VF-53 "Iron Angels" on board of USS Kearsarge; Korea, 1952 (Whif/Kitbashing) by dizzyfugu, on Flickr

1:72 Grumman G-79B/F9F-1 "JetCat"; aircraft "307/S" of the US Navy VF-53 "Iron Angels" on board of USS Kearsarge; Korea, 1952 (Whif/Kitbashing) by dizzyfugu, on Flickr

1:72 Grumman G-79B/F9F-1 "JetCat"; aircraft "307/S" of the US Navy VF-53 "Iron Angels" on board of USS Kearsarge; Korea, 1952 (Whif/Kitbashing) by dizzyfugu, on Flickr

The Panther was eventually favored as the USN's first operational jet day fighter and put into production, but the F9F-1 showed much potential as a fast fighter bomber. Through pressure from the USMC, who was looking for a replacement for its F7F heavy Tigercat fighters, a production order for 50 JetCats was eventually placed, later augmented to 82 aircraft because the US Navy also recognized the type's potential as a fast, ship-borne multi-role fighter. Further interest came in 1949 from Australia, when the country's government was looking for a - possibly locally-built in license - replacement for the outdated Mustang Mk 23 and De Havilland Vampire then operated by the Royal Australian Air Force (RAAF). Both Grumman designs were potential contenders, rivalling with the domestic CAC CA-23 fighter development.

The Grumman Panther became the most widely used U.S. Navy jet fighter of the Korean War, flying 78,000 sorties and scoring the first air-to-air kill by the U.S. Navy in the war, the downing of a North Korean Yakovlev Yak-9 fighter. Being rugged aircraft, F9F-2s, -3s and -5s were able to sustain operations, even in the face of intense anti-aircraft fire. The pilots also appreciated the Panther's air conditioned cockpit, which was a welcome change from the humid environment of piston-powered aircraft.

The F9F-1 did fare less glamorous. Compared with the prototypes, the T38 turboprop's power output could be enhanced on service aircraft, but not on a significant level. The aircraft's original, rather sluggish response to throttle input and its low-speed handling were improved through an eight-blade contraprop, which, as a side benefit, countered torque problems during starts and landings on carriers.
The JetCat's mixed powerplant installation remained capricious, though, and the second engine and its fuel meant a permanent weight penalty. The aircraft's complexity turned out to be a real weak point during the type's deployment to front line airfields in the Korean War, overall readiness was – compared with conservative types like the F4U and also the F9F-2, low. Despite the turboprop improvements, the jet booster remained necessary for carrier starts and vital in order to take on the MiG-15 or post-war piston engine types of Soviet origin like the Lavochkin La-9 and -11 or the Yakowlev Yak-9.

Frequent encounters with these opponents over Korea confirmed that the F9F-1 was not a "naturally born" dogfighter, but rather fell into the escort fighter or attack aircraft class. In order to broaden the type's duty spectrum, a small number of USMC and USN F9F-1s was modified in field workshops with an APS-6 type radar equipment from F4U-4N night fighters. Similar to the Corsair, the radar dish was carried in a streamlined pod under the outer starboard wing. The guns received flame dampers, and these converted machines, re-designated F9F-1N, were used with mild success as night and all-weather fighters.

However, the JetCat remained unpopular among its flight and ground crews and, after its less-than-satisfactory performance against MiGs, quickly retired. After the end of the Korean War in July 1953, all machines were grounded and by 1954 all had been scrapped. However, the turboprop-powered fighter bomber lived on with the USMC, which ordered the Vought A3U SeaScorpion as successor.

1:72 Grumman G-79B/F9F-1 "JetCat"; aircraft "307/S" of the US Navy VF-53 "Iron Angels" on board of USS Kearsarge; Korea, 1952 (Whif/Kitbashing) by dizzyfugu, on Flickr

1:72 Grumman G-79B/F9F-1 "JetCat"; aircraft "307/S" of the US Navy VF-53 "Iron Angels" on board of USS Kearsarge; Korea, 1952 (Whif/Kitbashing) by dizzyfugu, on Flickr

1:72 Grumman G-79B/F9F-1 "JetCat"; aircraft "307/S" of the US Navy VF-53 "Iron Angels" on board of USS Kearsarge; Korea, 1952 (Whif/Kitbashing) by dizzyfugu, on Flickr

1:72 Grumman G-79B/F9F-1 "JetCat"; aircraft "307/S" of the US Navy VF-53 "Iron Angels" on board of USS Kearsarge; Korea, 1952 (Whif/Kitbashing) by dizzyfugu, on Flickr

1:72 Grumman G-79B/F9F-1 "JetCat"; aircraft "307/S" of the US Navy VF-53 "Iron Angels" on board of USS Kearsarge; Korea, 1952 (Whif/Kitbashing) by dizzyfugu, on Flickr

General characteristics:
Crew: 1
Length: 40 ft 5 in (12,31 m)
Wingspan: 43 ft 5 in (13,25 m)
Height: 15 ft 6 3/4 in (4,75 m)
Wing area: 250 ft² (23 m²)
Empty weight: 12,979 lb (5,887 kg)
Gross weight: 24,650 lb (11,181 kg)

Powerplant:
1× Allison T38E turboprop, rated at 2,500 shp (1,863 kW) plus 600 lbf (2.7 kN) residual thrust
1× Westinghouse J34-WE-13 turbojet booster with 3,000 lbf (13.35 kN)

Performance:
Maximum speed: 507 mph (441 kn; 816 km/h) at 30,000 ft (9,100 m)
497 mph (432 kn, 800 km/h) at sea level
Cruise speed: 275 mph (443 km/h; 239 kn) at 30,000 ft (9,100 m)
Stall speed: 74 mph (119 km/h; 64 kn) with flaps
Range: 2,500 mi (2,172 nmi; 4,023 km)
Service ceiling: 47,000 ft (14,000 m)
Rate of climb: 5,300 ft/min (27 m/s)
Wing loading: 71 lb/ft² (350 kg/m²)
Thrust/weight: 0.42

Armament:
4× 20 mm (0.79 in) AN/M3 cannon in the outer, foldable wings with 220 RPG
Underwing hardpoints and provisions to carry combinations of up to 6× 5 " (127 mm) HVAR
missiles and/or bombs on underwing hardpoints, for a total ordnance of 3,000 lb (1,362 kg)

1:72 Grumman G-79B/F9F-1 "JetCat"; aircraft "307/S" of the US Navy VF-53 "Iron Angels" on board of USS Kearsarge; Korea, 1952 (Whif/Kitbashing) by dizzyfugu, on Flickr

1:72 Grumman G-79B/F9F-1 "JetCat"; aircraft "307/S" of the US Navy VF-53 "Iron Angels" on board of USS Kearsarge; Korea, 1952 (Whif/Kitbashing) by dizzyfugu, on Flickr

While it is not a prefect recreation of the Grumman G-79B, I am quite happy with the result. The differences between the model and the original design sketch can be explained through serial production adaptations, and overall the whole thing looks pretty conclusive. In fact, the model appears from certain angles like a naval P-51 on steroids, even though the G-79B was a much bigger aircraft than the Mustang.

zenrat · May 02, 2018, 03:22:45 AM

Fantastic. Excellent work there Dizz.

Experiments with the relevant Hasegawa kits have shown a mixed power aircraft could be built very simply by gluing a Zero engine and cowling onto the nose of a Panther.
Wouldn't look this good though.

Dizzyfugu · May 02, 2018, 04:07:56 AM

Quote from: zenrat on May 02, 2018, 03:22:45 AM
Experiments with the relevant Hasegawa kits have shown a mixed power aircraft could be built very simply by gluing a Zero engine and cowling onto the nose of a Panther.

LOL. Glad you like the end result.

Knightflyer · May 02, 2018, 04:25:35 AM

That looks magnificent

Totally believable as one of those post-war 'exotic' projects having made it into production. WELL DONE SIR

NARSES2 · May 02, 2018, 06:27:16 AM

Outstanding