Airborne Awesomosity

The Boeing B-50 – A Super SuperFortress

The Boeing B-50 Superfortress

[image credit –]

At the beginning of the Cold War there was still a need for new Strategic bombers but no time to wait for development of the new aircraft. Find out how an old design was refitted and would continue to serve its country for more then two decades.



Boeing B-44 prototype

[image credit –]


Starting in 1944 there was a need to improve the Boeing B-29’s performance.  Pratt and Whitney had a larger engine available in the form of the Wasp Major of four thousand three hundred and sixty cubic inches of displacement.  This offered an increase of more then eight hundred horsepower over the R-3350 powering the B-29. To test this an airframe was given to Pratt and Whitney for testing.  The B-44 would be a one off proof of concept but it showed enough promise to lead to the next major modifications to the still young Superfortress.


Pratt and Whitney R-4360 Cutaway

[image credit Wayne Moyer 2011]

Changes to the B-29/B-44 included moving to a lighter weight aluminium and a move to a taller rudder. One that was tall enough to include a mechanism to fold the top down to fit in hangers of the day.  Defensive armament was  increased to fifteen fifty caliber machine guns in four turrets.  Once when they got in service they would only be equipped with the tail gun.


Boeing B-50 Equipped With Treads For Use On Rough Surfaces

[image credit –]


All of the changes led to only forty percent of the original B-29 parts being shared. With this in mind they went after a new designation for the aircraft. It would be known as the B-50. The real reason for the name change was because they had plenty of B-29’s left after the war and no money in the budget for upgrades to wartime projects. Giving it a new name more or less tricked Congress into funding it.  Thankfully it turned out to be money that was far from wasted.

The B-50 only served in Korea briefly before being pulled out due to the threat of the Mig-15 fighter. The aircraft’s role in the US Air Force was far from over.  After the B-50 showed the value of air to air refueling by doing a round the world flight without landing.  The Air Force saw  the need for this capability in normal service.  B-50’s were converted to KB-50’s and fuel was stored in the bomb bays. In this function they would lead the way to the future showing the usefulness of this concept. During their lifetime they would have two auxiliary jet engines added to allow them to fly fast enough to be above the stall speed of the jet fighters needing their fuel. Of note is that the jet engines on the KB-50’s were designed to run on high octane av-gas and feed off the primary fuel supply of the bomber.


KB-50 Refueling F-101, F-100, and B-66


The B-29 would prove to a very versatile airframe being continually updated through the forties and fifties.  Serving her country until 1965 when far better technology was available. It would be the last piston engine bomber bought by the US Air Force.  An end to an era starting with the Wright Bros first sale to the US Army.


  • CaptianNemo2001

    Massive engines are an understatement.
    On the engine change over each new engine added 800 hp to the plane.
    B-29 = 8,800 total hp. B-44/50 = 12,000hp.

    Performance B-29 VS B-50 // = separation.
    B-29 Maximum speed: 357 mph (310 knots, 574 km/h)
    B-50 Maximum speed: 394 mph (634 km/h; 342 kn) at 30,000 ft (9,150 m)

    B-29 Cruise speed: 220 mph (190 knots, 350 km/h)
    B-50 Cruise speed: 244 mph (212 kn; 393 km/h)

    B-29 Combat range: 3,250 mi (2,820 nmi, 5,230 km)
    B-50 Combat range: 2,394 mi (2,080 nmi; 3,853 km)

    B-29 Ferry range: 5,600 mi (4,900 nmi, 9,000 km, [58])
    B-50 Ferry range: 7,750 mi (6,735 nmi; 12,472 km)

    B-29 Service ceiling: 31850 ft [20] (9,710 m)
    B-50 Service ceiling: 36,900 ft (11,247 m)

    B-29 Rate of climb: 900 ft/min (4.6 m/s)
    B-50 Rate of climb: 2,200 ft/min (11 m/s)

    B-29 Wing loading: 69.12 lb/sqft (337 kg/m²)
    B-50 Wing loading: 70.19 lb/sq ft (342.7 kg/m²)

    B-29 Power/mass: 0.073 hp/lb (121 W/kg)
    B-50 Power/mass: 0.115hp/lb

    What is interesting to note is that the Pratt & Whitney R-4360 Wasp Major could be boosted to well over 4,300 hp from the factory (3200 kW) using two large turbochargers in addition to the supercharger.

  • sporttruck

    The B-50 was also converted into the WB-50, a weather research aircraft.

    • fodder650

      It got converted into quite a few things. I was going to post another story on yet another unproduced version of it as well. The B-54 was to have four R-4360-51 Variable Discharge Turbines on it. A last gasp for piston technology. There isn't much online about it but I still may do a post about how they planned on using its exhaust to run a turbo that exhausted in a jet like fashion.

      • sporttruck

        That will be very interesting to read. We have both a WB-50D and a KC-97L on display. Our volunteers just finished detailing the inside of the WB-50D.

      • CaptianNemo2001

        The XF-12 had VDT and it seems, from reading between the lines, that it was temperamental at times. It was a very interesting topic and I think I might have an article or two from my own digging somewhere on the VDT. There are not many photos or models of the VDT online.

        • fodder650

          Nemo you have writer privileges here don't you? If you do we can look at our sources and have you write it up.

          Sporttruck – If I remember right the XB-54 to use this engine was called the "Ultrafortress". I will need to do a writeup on that aircraft at least.

          • CaptianNemo2001

            I really haven't seen much on the VDT to even put an article together. I have yet to locate a full variant's list for the R-4360 just to have. I don't have writers privileges and my HTML is more or less crap but it is slowly improving.

            I might need to find a copy of this:
            R-4360: Pratt & Whitney's Major Miracle by Graham White

            But it does not come cheap. I might, however, get a copy by February. We'll see. IF, and a big IF, I do, I will find a way make it more accessible.

            There are models of the XB-54 around, for images, I saw some references to them recently.

          • fodder650

            Alright well then its settled. I'll get a post up on it tomorrow with what I have about it.

          • fodder650

            BTW go to

            Download the PDF file on the engines history. It was, apparently, written during the production run and will tell you more then you ever wanted to know about it.

          • CaptianNemo2001

            I should scan in some of the stuff out of the October 1942 power plant manual. So many crazy things on supercharging and fuel's.

          • CaptianNemo2001

            According to

            The Wasp major C4 would have been the "over-the-top" version. With 4,800 hp and all the mechanical goodies from VDT to 3cc of T.E.L. per gallon of fuel and Fuel Injection to boot. All in a nice 3820lb package or 1.2565 HP per pound. Although if we look at the details of the C5 version its possible that not all of the weight was factored in on the C4.

          • fodder650

            Of course then you see the size of the thing it would have required a B-36 to package the darned thing. The VDT piece was nearly as big as the R-4360 itself.

          • CaptianNemo2001

            But just think, in all seriousness, what could be done today with new alloys, oil cooled pistons, and a long list of other tricky ideas to get more power and efficiency out of an engine. I wonder if they could reliably get 5,000 – 5,500 HP from a 4360. It would be fun to see a total re-engineering of the engine from the ground up. Stiffer, Lighter, Stronger, More power, More efficient and More time between overhauls.

            And then build a single seater around it to go fast with 1-2 engines…

          • fodder650

            Probably easier to look at engine development in top fuel dragsters to see where the technology would have led. Even if those aren't supposed to last. Maybe what they have done with marine motors.

          • CaptianNemo2001

            It would be interesting to see just how far they could go and still get 800 hours of reliable service from the engines. The tech involved in Formula 1 would also work OR, for more reliability, the tech from the Sprint Cup series in NASCAR.

      • CaptianNemo2001