How To Build A 4,300hp Aviation 'Wasp Major' In The 1930s?

known as one of the largest living piston engines ever in aviation this 28 cylinder Marvel was one of a kind in the real working aircraft out there Brett and Whitney managed to get things right and achieved node wealthy Success With It although it came too late to be used in the war it proved useful even after however during development things would not go as easy and the engineers had to think outside the box to finish this challenging assignment foreign [Music] America had not been involved in the World War II yet but Brett and Whitney knew it was coming and the company's aeronautical engineer Leonard s Hobbs cut the opportunity to design an engineering monster today we know that it was the last generation of large pace and aircraft power plants and at the same time one of the greatest challenges in the history of piston engine developers this is the pret and Whitney r4360 was Major its development was tough as it suffered from cooling issues oiling issues failing crankshafts and aerodynamic efficiency it nearly seemed like a mission impossible but Brett and Whitney would not give up and it was Mage saw the use of single up to 8 units on an aircraft typically for an air radial engine they used to be air-cooled simple and kind of natural in its application however cooling such a large engine is not as straightforward as it seems and pnw attempted to design liquid cooled cylinders without a successful effort the was Major was given air cooled cylinders of 146 by 152 millimeters from a smaller 18 cylinder r2800 being a 28 cylinder the decision was to make it a four row a radial unit this equals 4 7 cylinders into a single crankcase resulting in a 71.5 liter displacement foreign every 25.714 degrees of Revolution and given by a set of seven cylinders in a row it requires 51.429 degrees offset between them then the real offset is basically up to the engineers and they settled on a figure of 12.857 degrees with such a design it gained the nickname corn cup for its pure look to even out the row offset in the timing the far throw crankshaft was designed the same way gradualness offset by 12.857 degrees plus 180 degrees to issue a single combustion every 25.714 degrees of Revolution to put it into perspective these are the individual throw angles during a full 720 degree cycle and a relative to throw a number in the cylinders was a tricky task too with as many cylinders in such a shape hence each row was numbered with a letter starting at the rear with the a up to D with the uppermost cylinder being the number one and Mark clockwise up to seven they looked at it as a seven inline four cylinders and with a single magnet of failure the engine will only lose 4 cylinders with minimal engine stress due to perfect even firing after designing the firing order and intervals the Paramount thing is the General Internal design and materials of the was Major aircraft engine makers always look for the best balance between weight and durability for a radial Engineers had to determine whether to go with a build up crankshaft with a single piece Rod a single piece crankshaft and split rods eventually they went for a two piece Master Rod which then holds all the other six slave rods it was rigorously designed as a single Master rod with a single lead and indium silver plane rod bearing encounters over 1100 horsepower and has to cope with it even though a large portion of that doesn't end at the output shaft being a top secret project some red herrings were implemented not to give away the fundamental design such as sketching the fifth crank throw and then Machining it off later after delivery first cranks tended to break at the cranked cheeks but with the help of a vibration expert JP then hardgock counter-intuitively he devised removing some material and the problem was gone ever since the first variant of the WASP series The are for the infinity flourished aluminum has been found as the best material for crankcases for its strength and especially low weight it was Major accommodates a five piece case each played readily at the axis of the cylinders the three middle main crankshaft bearing sections were made of magnesium and pressed inside a steel ring cylinders themselves were interchangeable which was not a common practice in similar engines in addition the front section housed a Magneto drive oil Scavenging pumps and a planetary gear set for a single or twin Contra rotating propolis the rear housing accommodated a magnesium supercharger casting intake Cabaret later and other accessories pushers had fans for additional Cooling in the rear section as well and could consume up to 200 horsepower through the combustion Chambers and twin spark plugs per cylinder the r4360 was an overhead valve engine with a single intake valve at the front and a single exhaust valve at the back of the cylinder there is a cam ring to drive them via push rods and this engine used five of them two outers and three inners between the rows the first operated zero intake valves the second one managed zero exhaust valves and zero intake Valves and so on up to the last one operating Aero Exhaust valves one of the fundamental problems of a multiro radial engine is cooling even with piston offset there was Major required a different approach heads were made of forged aluminum and designed to keep engine stress low and high temperature below 2 and 60 degrees of Celsius interestingly materials like cup was considered for better heat transfer but it's hardly comparable to the weight of aluminum furthermore special cooling path when made for each Bank forcing air to enter at the front and cool eats on the completely up to the rear exhaust side Engineers really had to think this out as on a 37 degree celsius warm day it was Major required up to 22 kilograms of air each second no matter how important the cooling was it made it impossible to accommodate the regular type of intake and exhaust headers consequentially the intake was routed from a bow the oil system was not easy to make either it had dried some lubrication but Scavenging was the main issue especially as the WASP major was capable of extremely steep climb angles during which it would not scavenge normally to what on the r2800 they gained about 150 horsepower just improving oil Scavenging depending on the tuning it used various types of superchargers sometimes combined with an inch cool and turbos the engine was massive so even the entry model made about 2650 horsepower but the most of the variants were about the 3500 horsepower figure the turbocharged model was the most powerful with 4 300 horsepower at 2800 RPM a Soviet sweatsuna as-2 and BMW 803 were in the same ballpark with about 82 to 83 liters of displacement but especially the liquid cooled BMW which eventually never left a development stage was twice as heavy as the worst major and had basically the same power on the other hand the surveyed unit would consume half of the power Just for cooling at 15 000 meters just think about it how difficult it is to create such marvelous and large engine as they was mainly basically the largest American aircraft unit just before such huge piston engines would not be produced anymore in aviation although it came too late for the war replication nearly 19 000 of them were built for dozens of airplanes which is a tremendous success the film Aviator introduced two models with the boss major Helix xf-11 records aircraft and the Magnificent and gigantic birchmade Hughes H4 Hercules nicknamed Spruce Goose with eight of the worst Majors this one can be seen in McMinnville Oregon the light development of divorce major meant that it could not attend the war itself where it was mainly targeted however it showed its capabilities and Commercial flying which on the other hand was unprofitable without government subsidy with its absurdly complex design the retirement of the k ac97 and c97 US Air Force aircraft in the 1970s marked the end for this specific engine for gold admitted hers left speechless seeing the was Major in the flesh [Music]

Channel: VisioRacer

Views: 302,013

Keywords: VisioRacer, engine, sound, Pratt Whitney, Wasp Major, R-4360, 4 row, radial engine, 28 cylinder, Boeing

Id: iggsIWHwIx4

Length: 10min 37sec (637 seconds)

Published: Sat Oct 01 2022