Author Topic: Big Jugs  (Read 395 times)

Offline apophenia

  • Patterns? What patterns?
Big Jugs
« on: October 17, 2020, 08:10:31 AM »
No, not that kind! This is another concept spinning off from a suggestion by sporting25.
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'Big Jugs' - The Long-Legged Republic P-47P 'Tip-Tank T-Bolt'

By the end of the European campaign, Republic Aviation found its products being outstripped by the longer-legged but nimbler P-51 Mustang. Worse, North American was about to introduce its P-82 Twin Mustang which would have the range of a P-51 while carrying the offensive load of Republic's huge P-47 Thunderbolt. The response from Republic Aviation came in two forms. Chief Engineer, Alexander Kartveli, devised the longer-range P-47N Thunderbolt with extended 'wet' wings incorporating a further 186 US gallons of fuel - for a total of 1,266 US gallons - giving this aircraft a range of 2,350 miles. [1] The long-winged P-47N entered production at Republic's Farmingdale, NY plant. But there was a problem. Republic Aviation was shortly expecting orders for its evolved P-72 'Superbolt' which had the original, 'short' wings of the P-47D.

To preserve production of the 'short' wing, engineer Herbert Lindblad and his team were detailed to explore alternative range-extending solutions for future production at the Republic Aviation factory in Evansville, Indiana. Additional underwing drop tank pylons were rejected after wing tunnel testing revealed excessive drag.  Better results were found by mounting the extra fuel at the wing tips. In theory, such an arrangement should reduce wing bending moments and prevent drag-inducing swirl about the wing tips. Lindblad suggested this set up as a modification to the P-47D wing - with some stiffening of the outer spar structures. With Lindblad's suggestion accepted, the USAAF ordered the P-47P-1-RA straight off the drawing board. However, Alex Kartveli decided that the tip-tank concept should be tested on Republic's P-47C 'mule'.

"As unfathomable as the clouds, move like a thunderbolt"

Weighted to simulate full fuel load in dummy tip tanks, the 'mule' was taken aloft from Farmingdale, NY by test pilot Lowry Brabham in late January 1945. The wingtip tanks performed exactly as predicted, exhibiting few vices. However, the simulated weight of a full fuel load was worrying. Fuel alone would increase take-off weight by almost 1,600 lbs over the P-47N. Problems with burst tires on take-off were anticipated. For emergency landings, the fuel wingtip tanks would have to be 'punched off' to avoid overloading the main undercarriage. To address these weight concerns, the wingtip tanks were scaled down. The new tanks - flattened sagittally - each held 120 US gallons of fuel. This alleviated the overload issue but also reduced the aircraft's range advantage over the P-47N. On the other hand, it was hoped that future Evansville-built P-72s would still accommodate the 'full-sized' tip tanks.

USAAF procurement officers were less sanguine about that lost advantage. Indeed, official USAAF favour was decidedly turning towards the Mustang and Twin Mustang for the PTO. It was decided that P-47P production would proceed at Evansville only until the plant was ready to switch over to the higher-priority tip-tanked P-72C model. As a result, only 149 P-47Ps were built - 109 P-47P-1-RAs and 40 P-47P-2-RAs (with minor equipment changes). [2] All operational 'Ps were issued to units of the 350th Fighter Group which, having redeployed from Italy, was re-equipping in Panama for service in the Pacific. Today, the P-47P is most often associated with the Legião Lusitana - two Portuguese-speaking squadrons assigned to the 350th FG. These were 1º GAVCA(B) (Grupo de Aviação de Caça - Brasileiro) - veterans of the 350th's Italian campaign - and the newly-formed 3º GAVCA(P) (Grupo de Aviação de Caça - Português). [3]

'Os Grandes Jarros' - Republic P-47Ps of the Legião Lusitana

Personnel from Brazil's 1º GAVCA had stood down in Italy on 01 June 1945 and shipped out for Recife for R&R back home. On 09 July, the unit re-embarked at Rio de Janeiro for transport to Panama City to rejoin the 350th FG and convert to the new Republic P-47P model fighter. They were joined there by Portuguese personnel arriving by sea from Lisbon. [4] Once training was complete, the 350th FG shipped out from Panama City for Iwo Jima (Ie Shima). There, the four P-47P-operating squadrons -  the 345th Fighter Squadron, 347th FS, 1º GAVCA(B), and 3º GAVCA(P) - operated from Field No. 2. Although intended primarily for ground-attack, the Legião Lusitana squadrons found themselves flying bomber escort missions for USAAF B-29 Superfortress formations.

Top Republic P-47P-1-RA of 1º GAVCA(B) with 500 lb GP bombs on its wing racks. Markings on the natural metal airframe are the 350th FG's PTO 'Apple Green' recognition colours on cowling, spinner, and tip-tanks. Like all GAVCA(B) aircraft, Brazilian rudder stripes are displayed. The Força Aérea Brasileira roundel has been applied over the US 'stars and bars'.

Note that this 'Trator Voador' ('Flying Tractor') has personel markings - 'Vamos' nose art (inset) and Legião Lusitana crossed flags on the vertical fin - but has yet to apply its individual aircraft code (B4 for 'Jambock Quatro'). This fighter would be lost to ground fire over Nagoya’s Akenagohara airfield on 22 January 1946, pilot 2º Ten.-Av. João Vieira Pereira going down with his aircraft.

Bottom Republic P-47P-1-RA of 3º GAVCA(P), Força Aérea Portuguesa flown by Alferes António Maria de Coutinho. Standard US 'stars and bars' are worn on the wings but the fuselage roundel has been overpainted with the Cruz de Portugal (in white following the standard PTO practice of avoiding red markings). Rudder stripes are standard FAP 'VeV' (Verde e Vermelho or Green and Red).

This P-47P wears the usual badge of 3º GAVCA(P) on the tail fin but repeats its cachorro galgo (greyhound) motif on the cowling (inset). 3º GAVCA(P)'s unit code was to be 'OK' - inherited from Esquadrilha 4, like the cachorro galgo badge. However, in-theatre, aircraft received truncated, 2-letter individual codes. Alf de Coutinho's aircraft would have been 'OK+L' but was, instead, marked as 'LK' (portside) and 'KL' (starboard). This P-47P was returned to US control when 3º GAVCA(P) was stood down at Itami Air Base near Osaka.

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[1] For the P-47N, the wings were extended from the centre (with tips clipped). Extra fuel tanks were arranged around the main undercarriage wells - making up an extra 93 US gallons of fuel per wing.

[2] Although Republic's tip-tank conversion of the P-47C 'mule' was essentially private venture activity, the P-47P contract was retroactively adjusted to include this conversion work as airframe No.1 in an order for 110 P-47P-1s. The order for P-47P-1-RAs was further amended to substitute 40 P-47P-2-RAs to allow for minor radio and hydraulic system changes. All P-47P-3-RA and eight-gunned P-47P-4-RA orders were cancelled and replaced by equal numbers of P-72C-1-RAs and P-72C-2-RAs.

[3] Technically, there were four squadrons within the Legião Lusitana. The additional squadrons were 2º GAVIA(U) - the Grupo de Instrução de Aviação - Unificado, a training unit formed on P-47Ds at Recife in early January 1946 - and 4º GAVCA(B) - a second Brazilian fighter unit which was still working up at time of the Japanese surrender. In Brazil and Portugal, the Legião Lusitana was officially known as the Grupo Operacional de Aviação de Caça - Pacífico or Fighter Operational Group - Pacific (GOAC-PAC).

[4] Many of the Portuguese pilots had previous experience with US-built aircraft having flown Bell P-39L Airacobras with Esquadrilha 4 at Ota. Ironically, at least some of Esq 4's interned Airacobras had originated with the 350th Fighter Group.
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Offline Sport25ing

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Re: Big Jugs
« Reply #1 on: October 17, 2020, 05:30:14 PM »
WOW!!!  ;D

Online finsrin

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Re: Big Jugs
« Reply #2 on: October 17, 2020, 05:58:22 PM »
Big Jugs with tip tanks are like a warmup for the F-84.

Offline GTX_Admin

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Re: Big Jugs
« Reply #3 on: October 18, 2020, 03:06:00 AM »
I have just the decals for you...

All hail the God of Frustration!!!

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Offline buzzbomb

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Re: Big Jugs
« Reply #4 on: October 18, 2020, 06:04:32 AM »
 :smiley:

and another  :smiley: for the decal selection

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Re: Big Jugs
« Reply #5 on: October 19, 2020, 03:15:17 AM »
All hail the God of Frustration!!!

You can't outrun Death forever.
But you can make the Bastard work for it.

Offline apophenia

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Re: Big Jugs
« Reply #6 on: October 19, 2020, 09:19:28 AM »
Thanks folks. And finsrin ... good eye! The tip-tanks were indeed purloined from an F-84  ;)

I have just the decals for you...

Perfect!  ;D
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Offline Robomog

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Re: Big Jugs
« Reply #7 on: October 20, 2020, 04:15:40 PM »
Someones gotta say it..........

"What a fine pair of jugs!"   ;) ;D ;D

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Offline apophenia

  • Patterns? What patterns?
Re: Big Jugs
« Reply #8 on: October 22, 2020, 07:14:13 AM »
I decided to go on with the P-72C ...
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With the end of P-47P production, Republic's Evansville plant switched its line to tip-tanked P-72C-1 'Ultrabolts'. The most evident changes was the longer R-4360-19 'corn cob' engine and propeller spinner. Less obvious was the absence of the P-47's bulky, exhaust-driven turbocharger. Replacing the turbo in the rear fuselage was a huge, fluid-coupled, 2-stage supercharger. In a sense, the 'Ultrabolt' was really a new aircraft but the P-72C's wings and empennage were identical to those of the P-47P.

The first 'Ultrabolts' were Farmingdale-built 'plain-winged' P-72A-1 models with R-4360-13 engines and 13.5 foot diameter, 4-bladed propellers. Only 20 'As were completed before the contract was amended to tip-tanked P-72D-1s. [1] First into combat were the P-72C-1s. Like the Farmingdale 'Ds, these Evansville-built fighters were fitted with 5-bladed Hamilton Standard Hydromatic propeller with a reduced, 13 foot diameter. [2] The latter was much lighter and simpler than the second prototype XP-72's contra-props and eliminated the need for 3-point landings dictated by P-72A's reduced prop-tip ground clearance.

With deliveries begun in late October 1945, the P-72C-1s were late 'in theater'. However, the timing was vital. The first of the Japanese jet-propelled fighters were beginning to appear over the Home Islands. The P-47N and 'P had trouble matching the jets. However, with a 20 mph gain at altitude, the 'Ultrabolt' had a better chance of 'bouncing' jet fighters like the Kawasaki Ki-208 Tsubame. [3]

Top 'Big Girl' belonged to the 333rd Fighter Squadron (318th FG, 7th Air Force). This P-72C-1 was one of the first 'Ultrabolt' combat loses when 2nd Lt. H.S. Kavanagh failed to return from a bomber escort mission over northern Shikoku. Kavanaugh's fighter probably came down in the Seto Inland Sea (Setonaikai).

(Inset) 'Big Girl' nose art.

Bottom Despite its more flamboyant markings, 'Icky & Me III' [4] also belonged to the 333rd FS. This fighter was flown by Capt. Jack Payne from Okinawa before moving to advanced bases on Kyushu.

(Inset) 'Flying Dragon' personal insignia inherited from the original 'Icky & Me'.

________________________


[1] The P-72B was a planned 'A derivative armed with a quartet of 37 mm wing guns. This proposed cannon-armed variant was never built. At Farmingdale, the 'D-1s were quickly eclipsed by P-72Es with revised equipment including Curtiss Electric C742S-C6 propellers.

[2] This new HamStan unit was effectively a much-enlarged British Rotol 5-bladed prop scaled to suit five of the blades from P-47's 24E50-65 propeller.

[3] The 'Jet Hien' still had a nearly 100 mph speed advantage. The Ki-208s had to be caught slowing for a firing pass or when the 'Ultrabolt' was in a near-terminal dive.

[4] Then-Lt. Payne's original 'Icky & Me' was a P-47N. While on Iwo Jima, Payne briefly flew 'Icky & Me II', a P-47P-1 taken on loan from the 347th FS (350th FG) as a tip-tanked transition trainer for the P-72C.
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Offline elmayerle

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Re: Big Jugs
« Reply #9 on: October 22, 2020, 07:24:30 AM »
Beautiful!!  Your thoughts on P-72 design evolution mirror some of mine, particularly the five-bladed prop.  I could see a variant built with four (or perhaps six) 20mm cannon instead of eight .50-caliber machine guns but I can't see going to anything larger.

I like the idea of the five-bladed prop because it can use the engine's full power and it and it's driveshaft would be more robust than the two shafts and other mechanisms required for contra-props (now, for a stripped-down racing version, I could see the contra-props).

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Re: Big Jugs
« Reply #10 on: October 23, 2020, 02:22:18 AM »
 :smiley:
All hail the God of Frustration!!!

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But you can make the Bastard work for it.

Offline apophenia

  • Patterns? What patterns?
Re: Big Jugs
« Reply #11 on: October 23, 2020, 06:50:10 AM »
Thanks folks :)

Evan: Agreed, the contra-props make good sense for racers or other applications where fastidious maintenance practices are practical. Adding an extra 24E50-65 blade to a Rotol-style hub seemed a good solution to actual field conditions and the reliability needed for long over-water flights. I must admit, though, my main motivation was getting away from the RW XP-72's 3-point landing requirement.

I'm imagining that P-47Ns would cover shorter-range missions, leaving the longer stuff for the P-72Cs. Imagining a return of B-29s to Nagaoka - to finish off RIKEN's uranium enrichment programme, perhaps? [1] Escorting P-72Cs would be facing a return flight of at least 2,220 miles. It seems unrealistic to demand perfect three-pointers by less experienced pilots after six and a half hours in their cockpits. [2]

Armament: I've left the wing guns at six (as per RW P-72) for the weight savings ... at least, I assume that's why cut back from eight. I'm sure that the Thunderbolt wing could easily accommodate six 20 mm cannons. Alas, US industry seemed to have no luck whatever with building Hispanos during WW2 ;p

In my mind, the US 37 mm guns were past their 'best-before' by 1945 ... although, looking at the stats I'm not sure where that conclusion came from. Comparing the US 37 x 145R and UK 40 x 158R, there isn't a lot to choose from. Vickers S rounds had a slightly higher m/v and heavier shells (HE and AP) but not sufficient to rule out the US M4/M10 cannons.

Hmmm, this has me wondering about a mixed-calibre armament for the P-47. Maybe two underslung M10s backed up by a quartet of .50s?

______________________________

[1] Enrichment work in Yoshio Nishina’s lab at RIKEN (the Institute of Physical and Chemical Research) was effectively terminated by April 1945 B-29 raids on Nagaoka ... but the USAAF couldn't have been sure about that  ;)

On the subject of an IJAAF atomic bomb, is anyone developing on a scenario in which Masatoshi Okochi's work bear fruit by 1946? Two nuclear-armed nations facing off in the midst of a total war  :o

[2] Here, I've assumed a reasonably economical cruising speed of 350 mph. Distance is there-and-back with no allowances for zig-zagging escort patterns or active air combat.
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Offline elmayerle

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Re: Big Jugs
« Reply #12 on: October 23, 2020, 08:36:50 AM »
There have been some reports that Japan did have an A-bomb before the surrender and even some claims that it was tested.  Supposedly it was developed in what is now North Korea, in a facility for which the Chosin Reservoir supplied electrical power, and is an additional explanation as to why the Soviets wanted that territory.  I agree, though, that two nuclear-armed nations facing off in total war could get dicey.

Perhaps the six .50 caliber machine guns could be replaced by four 20mm cannon as was done on some versions of the Corsair and, IIRC, the Hellcat.

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Re: Big Jugs
« Reply #13 on: October 24, 2020, 01:37:28 AM »
There have been some reports that Japan did have an A-bomb before the surrender and even some claims that it was tested.  Supposedly it was developed in what is now North Korea

 ;D
All hail the God of Frustration!!!

You can't outrun Death forever.
But you can make the Bastard work for it.