The Forgotten HYPER Aircraft Engines of WWII

in the early 1930s in the Prelude to World War II the U.S Army and the U.S Navy needed production engines that could meet or exceed the one horsepower per cubic inch Benchmark at the time that power output had only been achieved by several purpose-built Racing Engines but no reproducible production engine had yet fulfilled this need as a result the US government financed several high performance or hyper engine projects and in today's video we'll be taking a look at some of these incredible forgotten pieces of engineering on May 23 1940 the Chrysler company wanting to assist the U.S government's military preparedness program embarked on what would be a very expensive engine development program that would ultimately fail to deliver at the time the idea was to develop a hyper engine that would be a liquid-cooled monstrosity that generated over 2 000 horsepower the XI 2220 as it would become known was designed as an inverted v-type 16 cylinder engine with a Center Drive reduction gear realizing the necessity of maintaining a small frontal area for Optimum aerodynamics the engine's front section fit within a 34 inch diameter circle after creating a test engine in the early 1940s and beginning work on a single cylinder test bed the Air Force expressed interest on April 14 1941 and the engine program was given a contract for seven hundred and twenty thousand dollars testing on the first twin cylinder engine started on August 12 1941 an evaluation of the connecting rods bearings cylinder heads and barrels was started however before they could design a full-size engine the contract was amended noting the need for a fluid coupling for a Supercharger drive an axial type coolant pump and a radial type supercharger in addition to the axial variant the resulting change resulted in a contract price of 1.2 million and the resulting full-sized multi-cylinder engine was finished on July 30th 1942 in this first area the engine itself was complete however the rear gear case which included the rear supercharger in the accessory gear case hadn't yet been finished and as such the rear section was just a mock-up unfortunately for the XI 2220 tests were paused on September 19 1942 because of the destruction of the crankcase when a rod bearing seized and the rod broke going through the side of the crankcase however soon multi-cylinder engine number one was rebuilt and testing resumed on October 22nd 1942. on January 6 1943 a meeting was held in Detroit which was attended by General K.B wolf General fo Carroll and Colonel ER page with the express purpose of reviewing work on the XI 2220 contract by the end of the meeting they instructed the Chrysler Corporation to design a two-stage two-speed supercharger and to submit a program for building 100 full-sized engines this new demand was a tall order the work outlined for the addition of a two-stage supercharger required considerable Revision in addition the new critical altitude was to be designed for 25 000 feet in the lubrication coolant and electrical systems needed to be redesigned so they would remain functional at forty thousand feet as progress on the project continued the cost of the project ballooned to 13.3 million dollars which corrected for inflation would be nearly a quarter billion today as work continued so did the scope and complexity of the project such as the design and development of the axial supercharger testing of a fuel injection system and finishing the two-stage supercharger system however soon more fatigue issues began cropping up on June 19 1943 engine number three operated for over four minutes at 2 000 actual brake horsepower and nearly 4.5 hours above 1850. Callum Douglas in his book The Secret horsepower Race points out the similarities between the Chrysler V16 hyper engine and the German v12s which the Chrysler Corporation had been studying since the start of the war the crankcase was visually identical to the UMO 211 and the supercharger had a hydraulic coupling similar to the dp601 also it was inverted like both of them where Chrysler went wrong Douglas States was when they committed to only fitting the engine with two valves per cylinder rather than four this crippled the output of the engine which could due to its low running temperatures have capitalized on a higher power density another thing that eventually doomed the project was the mid-project redesign that would include a two-stage supercharger which cost the project valuable time they couldn't afford interestingly George hubner head of the IV 2220 program later designed the company's V8 automobile engines including the Chrysler Hemi engines culminating in one of the ultimate muscle car engines the awesome 426 Hemi these hemispherical Auto engine combustion Chambers were a direct descendant of the IV 2220s I remember wondering when I learned that most general aviation aircraft were powered by either Continental or Lycoming engines where were these manufacturers during World War II why weren't there p-51s powered by giant lycomings well the answer to that question is long and complex but for today's video we are highlighting one of lycoming's final attempts at creating the most hyper hyper engine ever created the XR 7755 yes that's 7755 cubic inches design work on the 7755 started in Earnest in 1943 and the ultimate design featured 36 cylinders each using 6.375 inch bore and six and three quarters inch stroke oriented in four rows of nine cylinders air cooling would be nearly impossible so they decided the engine would be liquid cooled interestingly the overhead camshaft featured two sets of Cam lobes that could be shifted in flight to optimize power or economy which might sound familiar and it should because that means that this giant radial was a VTEC like the XI 2220 this engine also unfortunately used only two valves per cylinder which would limit the power density it was ultimately capable of inside the engine the nose cased housed a complex propeller reduction gear that incorporated control rotating drives and two speeds the two-speed mechanism was hydraulically operated from the engine oil boosted to 300 PSI additionally a five-piece steel forged crankcase supported the four row 4-Piece crankshaft the crank itself was supported in five roller bearings in its single stage single-speed supercharger was supplemented by dual turbochargers Lycoming love to mention in their publicity with this engine that it burned enough fuel in an hour to run the average family automobile for one year and at 580 gallons an hour they probably weren't far off the oil flow was also a whopping 71 gallons a minute its power rating for its weight was perhaps unsurprisingly not so great only generating 5 000 horsepower for its massive six thousand and fifty pounds the reason for all this size was that the engine was intended to be fitted into a B-36 however due to political reasons the B-36 was instead powered by r4360s as such early b-36s were grossly underpowered and soon needed modification to include 4j47 Jets don't let the relatively small displacement number fool you when the right Corporation designed the r2160 they definitely intended it to break the mold in fact the r2160 ranks as one of the most complex aircraft piston engines ever attempted so much so that its complexity became its downfall you see what was interesting about the r2160 was that hidden in that displacement number were 42 cylinders with a four and a quarter inch bore and a 3.625 inch stroke designed on 14 cylinder modules of which three were used the company also had developed plans to create a 70-cylinder model made from five modules overall the engine had good design characteristics however the engine was liquid cooled which was not right aeronautical's area of expertise with six cylinders per row and seven total rows each cylinder Bank was a monoblock construction two valve hemispherical combustion Chambers and overhead camshafts were part of the cylinder head designed as this was a high speed engine the propeller reduction gearing was also overly complex with seven pinions each one driven from the cylinder head of a cylinder row which drove the reduction gear through a lay shaft the crankcase design was nine bolted together steel forgings and a built-up crankshaft allowed the use of One Piece Master rods with six articulating rods attached all crankshaft bearings were plain for takeoff the r2160 was rated at 2 350 horsepower at 4145 RPM with a weight of Just 2 400 pounds which met the one horsepower per cubic inch goal foreign [Music] 1930s the same sleep valve that gave rise to the Napier saver brought on by the influence of Harry Ricardo and Roy feden caused George Mead to believe liquid cooled sleeve valve technology was the wave of the future when Mead returned from his visit to England he signed a contract with the U.S Navy for an 1800 horsepower engine which would be called the x-1800 conceptually it was very similar to the saber as it was a liquid-cooled 25-cylinder h configuration however soon Mead's Health deteriorated and he was forced to run the x-1800 program from his home but soon after as Mead resigned from Pratt Whitney Luke Hobbs who took over the program canceled it as the Air corps became interested in the r4360 instead additionally the h-3730 which was a Navy request for an outgrowth of the x-1800 program continued through 1943 but it too was also eventually canceled the h-3730 being canceled was delayed because in the early 1940s Pratt Whitney had no other engines in the 3 000 horsepower category and the development of the r4360 he was still in its infancy so the dream of an American sleeve valve engine died but considering the issues Napier had dealt with to get their engine running properly there was probably a little chance they would have completed the engine prior to the end of the war so what can we learn looking back on these hyper engines well as history shows us timing is everything while some of these engines had impressive performance and Designs all of them shared a singular flaw their manufacturers attempted to design engineer and produce a completely revolutionary design in the midst of a war as we've seen throughout history the engineering cycles of these engines that would be successful were already nearly completed by the end of the 1930s in their respective horsepower races were won through iteration and Improvement rather than redesigning them entirely had many of these contenders had more time or different circumstances their promise might have yet been fulfilled but while Engineers were dealing with ironing out various fatigue issues and optimizing their forced induction systems more traditional engines such as the Pratt and Whitney radials and the Rolls-Royce V engines were already making history if you liked today's video don't forget to like And subscribe we're still trying to build a bigger viewership so if you could shoot us a subscription that would be great as always thank you for tuning in to flight Dojo we'll see you next time

Channel: Flight Dojo

Views: 262,134

Keywords: ww2, world war ii, aviation history, engineering, wwii aviation, warbirds, aeronautical engineering, second world war, wwii, lycoming, lycoming engine, chrysler xi-2220, lycoming xr-7755, Wright Tornado R-2160, Pratt & Whitney, Pratt & Whitney H-3730

Id: CfAR_762xr0

Length: 10min 54sec (654 seconds)

Published: Sun Oct 23 2022