Republic XP-72 - The 28-Cylinder Thunderbolt

The XP-72 is the ultimate version of the P-47, sharing wings and parts of the fuselage but now having a 3450hp R-4360 Wasp Major and many other modifications that elevated the performance of the airplane to one of the best propellers to ever exist.
Some modifications include a cooling fan, removal of the turbosupercharger in favor of a huge two stage supercharger and a 6 blade contra rotation propeller!

Check the details about the XP-72:

Performance, Armament and Armor from Spec.507 National Archives, 22 August 1944

Speed at WEP:

  • 405mph/651kph at Sea Level
  • 490mph/788kph at 25000 feet / 7620 meters

Climb at WEP:

  • 5250 ft/min / 26,67 meters/sec at Sea Level
  • 3 minutes 30 seconds to 15000 feet / 4572 meters

Engine Power:

Low Speed Power:

  • Sea Level:
    Normal: 2500 BHP
    Military (100%): 3000 BHP
    WEP: 3450 BHP

  • 15000 feet:
    Military (100%): 2750 BHP
    WEP: 3100 BHP

  • 25000 feet:
    Normal: 2200 BHP
    Military (100%): 2400 BHP

WEP High Speed Critical Power:

  • 3000 BHP at 25000 feet

Normal High Speed Critical Power:

  • 2200 BHP at 30000 feet


  • Empty: 11,476 lb
  • Design Gross: 14,444 lb
  • Alternative Gross: 15,313 lb


  • Length: 36’ 7’’
  • Span: 41’
  • Wing Area: 300 sq ft


  • 6x.50 with 267 rounds each
  • 2x500lb or 2x1000lb in external fuel tank shackles


  • Bullet-proof glass
  • Rear seat armor (see Erection & Maintenance Images)


History from the National Archives
  • In 1941 the P-47 had just entered production and the designers were already looking at the next evolution of the thunderbolt. It was obvious that for a big step in performance a new engine was required and P&W was just starting with the design of a new engine, one with the same cylinders of the R-2800 that powered the P-47 but this time it had 28 of them.
    So the decision was clear, the next evolution in performance of radial fighters would come from the hand of the R-4360 and so the XP-72 project started.

  • December 1942: The XP-72 was classified as ‘‘Project MX-189’’ and the R-4360 as ‘‘X-Wasp’’

  • March 1943: the general specifications of the XP-72 were settled by the Aircraft Laboratory Comments and a engine cooling fan was recommended


  • August 1943: It is decided to drop the XP-47J in favor of the XP-72 and Propeller Laboratory presents a Gear Ratio and Shaft Stress Study.

  • September 1943: an estimation was given for War Emergency Power performance with different propellers, conversations about P-72 deal are given, status of project is notified and fire extinguisher equipment is specified.


  • October 1943: Propeller and Gear Ratio Study:

  • November 1943: production of 100 P-72 was confirmed:

  • The first XP-72 prototype (43-36598) that was completed was fitted with the Curtiss Electric 14 ft 2 in single-rotation four-blade and a P&W R-4360-13 engine, which was probably the largest propeller fitted to a fighter. It was finished on 29 January 1944 and the aircraft’s first flight was made from Republic Field in Farmingdale, New York on 2 February 1944.

  • May 1944: 14 hours of flying time were completed in the first prototype and flight test of the second prototype was requested without fire extingushing equipment (CO2 bottles system) but it was denied.

  • June 1944: a new scheudle for P-72 delivering was approved.

  • The second XP-72 prototype (43-36599) used an Aeroproducts Dual Rotation six-blade 13 ft 6 in (4.11 m) diameter and was first flown on 26 June 1944. This aircraft was making a high-performance takeoff from Caldwell, New Jersey when an oil seal on the supercharger failed and caused a massive oil leak. Hot oil sprayed into the cockpit and on the outside of the canopy. The pilot managed to land it and while the aircraft could have been repaired, the XP-72 program ended soon after.

  • July 1944: High Speed Wind tunnel tests were not yet started and tests in the 7x10 Tunnel were scheudled to start on the 17 of July.

  • August 1944: After 10 hours of flying time of the 2nd prototype the flight tests were suspended until the 2nd stage is installed.


  • September 1944:

  • October 1944: Results of the 7 by 10 Wind Tunnel were presented.


  • November 1944: Revised Wind Tunnel program, notes about the new horizontal tail and the termination of the 100 P-72 order.

  • December 1944: Cancellation of 8-Foot High Speed Wind Tunnel tests and 7x10 Wind Tunnel test

Erection & Maintenance Manual Images by Graham White

Induction System:

Fuselage Structure:

Cowling System:

Exploded Assemblie Diagram:

Landing Gear:

Additional information for modellers by Justo Miranda



Do you also love this beast and would like to see it in game?
Vote and leave your thoughts on the comments :)


Would you like to see the XP-72 in-game?
  • Yes
  • No
0 voters


  1. Development of XP-72 Republic from the National Archives
  2. R-4360: Pratt & Whitney’s Major Miracle by Graham White (2006)
  3. Republic XP-72 Super Thunderbolt / Ultrabolt Fighter by William Pearce
  4. ACP Quarterly Experimental 1-OCT-1945 (page 18)
  5. Additional information for modellers by Justo Miranda

Honestly I’m surprised this hasn’t popped up yet, but still an absolute +1 from me


One of the wildest piston engined fighters to ever grace the sky. Absolutely yes.
But I dare not click the dropdown for hidden text in the OP labelled “erection images”.


Thanks! Yes it is a must, would be a fun plane.

That is how they name their manuals hehe, great images trust me ;)

1 Like

I clicked it and saw parts that are usually covered up! Erection images indeed. (There was even an "exploded assembly :O )
Personally I hope if this plane is implemented it can change its armament between the 50cal, 37mm and mix of both, as was planned for it.


Debatable… I think losing two of my freedom spreaders would definitely a down grade. How am I supposed to spread the American seed all over my enemies if I only have 6 guns instead of 8???


To clarify, this (^^) was a joke before anyone comes after me.

1 Like

I did not include that because in the first hand sources and photos I had I did not find any mention to 37mm guns.

I was also disappointed by the low amount of rounds per gun. But good enough still :)


That 6 bladed contra prop is so hot. +1000000


Has been a long overdue plane. May the Snail giveth us this masterpiece of a plane. +1


Gimme more superprops oh yah

1 Like

+1, thank you for suggesting this, we needed it )))))

1 Like

That would be a significant addition. An important superprop with great performance. I’m glad you erected this suggestion! +1


I only could find this from Spec.507 22 August 1944 that does not specify what guns it would use, only that it would have 33 rounds per gun.
Also I cant find any photo with the 37mm installed so I think in game it should use the .50cal configuration.

Dont play US aircraft nearly as much as I should but I would love to fly this +1 from me

1 Like

Yes it would be amazing to fly the P-72, thanks for the comment!

1 Like