Today we talk about the problem of identifying aircraft engines.
World War II-era aircraft used nothing more than three types of engines, piston, jet and rocket engines. The latter two categories were cutting-edge technologies at the time, equipped with limited models, and the common ones were just a few.
What both types of engines have in common is that they all have tail nozzles. Jet engines need to suck in air as an oxidant to work, so there is an air intake in front, and the rocket engine comes with its own oxidant, so there is no need to set up an air intake.
Meteor F.3 jet fighter
The Rolls-Royce Dervent jet engine used by the Meteor F.3
Me 163 rocket fighter
The Volta HWK 109-509 rocket engine used in the Me 163
Other aircraft that use propellers are equipped with piston engines, and if you look closely, they have both pointed heads and flat heads. The piston engine works by burning fuel in the cylinder, pushing the piston to move and driving the connecting rod and crankshaft to output power. The power of a single cylinder is limited, and multiple cylinder combinations are required to increase the output power, which in turn brings heat dissipation problems.
During World War II, the aircraft engine power was already very large, and the number of cylinders was also large. Liquid-cooled engines use coolant as a heat exchange medium, which is piped to a radiator installed elsewhere for circulation. Therefore, many of the liquid-cooled engine cylinders at that time used a V-shaped layout to be arranged in two columns, and the entire engine appeared to be very slender, and the engine fairing and the propeller fairing were combined to form a streamlined tip.
Sleek lines of the Bf 109G fighter
The DB 605 inverted V-type liquid-cooled engine used in the Bf 109G
The air-cooled engine is directly dissipated by the oncoming air flow, if the cylinders are arranged front and back, the rear exhaust cylinder is in contact with the air that has been heated by the front row, and the later the heat dissipation effect is worse. Therefore, air-cooled engines often arrange the cylinders around the central axis on a flat surface, called the star layout. At the end of World War II, as the engine power increased, the number of cylinders increased, and the air-cooled engine also had to arrange the cylinders front and back into two rows, but they were interlaced with each other, still to ensure that the rear exhaust cylinders could contact the cold air on the front.
With this layout, the engine cross-sectional area is naturally very large. And the propeller cover can not be too large, so as not to affect the windward area of the engine, so the front of the air-cooled engine is a thick flat head.
F6F fighter
The F6F uses the R-2800 twin Wasp twin exhaust cool star engine
These two engines in the use of military aircraft have their own advantages and disadvantages, all depend on the designer and user's preferences and trade-offs, many articles have also been introduced, we will not repeat it here.
Speaking of which, I am afraid that some readers will say old guns, aren't you all ABC stuff? Too basic, is it worth specifically mentioning? That's not necessarily true, this kind of appearance difference can only be called usual, since I took it out and said that there must be exceptions.
For example, the following aircraft, Spoo 2, what kind of engine do you say you use?
The only surviving Schipper 2M-100A restored in the 1980s
Old photos show the structure of the front of the engine compartment
This type of aircraft was heavily equipped with the Chinese Air Force when the War of Resistance broke out.
The Sbo 2M-100 on the Battlefield of China
I have seen Chinese self-media authors on the Internet say that it uses an air-cooled engine. In fact, the engine used in this kind of aircraft is marked on the model, Klimov M-100, a 12-cylinder V-type liquid-cooled engine - public information, can be found everywhere.
M-100 liquid-cooled engine
So what do you do when you say he's okay with a liquid-cooled engine? In fact, it is to put the radiator in front of the head. Similar layouts are very common in daily life, such as the following figure.
It is all too common for cars to have radiators in front of the engine
The drag of this layout is certainly large, wasting a major advantage of liquid-cooled engines, and may be acceptable if the aircraft is not too fast. But the Spoo 2 itself is known for its high-speed capabilities, so when the more powerful M-103 engine was replaced, the radiator was moved under the engine, and the front became a smooth pointed head.
Seb 2M-103
Because the M-100 was originally a licensed production version of the Spanish Cispano-Susa 12Y engine, and the 12Y engine was quite successful at the time, the series was almost the standard engine of the French Air Force in the 1930s, so there was a similar design in French aircraft.
Sispano-Susa 12Y engine
Mureaux.115 reconnaissance aircraft
MB.211 bomber
This kind of liquid-cooled engine has a large flat radiator in front of the layout of the First World War, and it is not uncommon in the post-war 20s and 30s, so I will not list them too much. Some people may have to say again, this design is very old-fashioned at first glance, that is, The Spoo 2 to the outbreak of the Soviet-German War is also obviously outdated, can not be regarded as a typical World War II aircraft, then please look at the following kind.
Surviving Ju 88D bomber
Close-up of the engine compartment
The Junkers Ju 88, known as Germany's best bomber of World War II, produced 15,000 air-cooled engines, do you see the photo of it using air-cooled engines or liquid-cooled engines?
The answer is liquid-cooled, with the exception of the Destroyer and Night Combat models and some of the long-range reconnaissance models using BMW 801 air-cooled engines, the vast majority of ju 88s are made with Jumo 211 and 213 series of 12-cylinder inverted V-cooled engines from Junkers' own jumo 211 and 213 series. Junkers designed a ring cooler at the front of the engine that integrates engine cooling and oil cooling. It is said that the reason for this arrangement is that the coolant line is the shortest, so the ju 88 series engines are flat regardless of air-cooled liquid cooling.
Jumo 211 engine
Jumo 213 engine
This layout seems to have its advantages in practical applications, so it continues to be used on jumo engine models derived from the Ju 88 and Ju 388.
In August 1944, the Ju 188A-2 crew celebrated the squadron's completion of 2,500 missions
There are also prototypes of the Fw 190D, Ta 152, Ta 154 and Me 264V-1, which also use Jumo series engines.
Surviving Fw 190D
Partially renovated surviving Ta 152H
Ta 154 night fighter
Use the Jumo 211-era Me 264V-1
as well as the Ar 240, He 219, Do 335, He 177 using the DB series of liquid-cooled engines.
Ar 240 destroyer
He 219 night fighter
Surviving Do 335 fighter
He 177 heavy bomber
It is worth mentioning that the He 177 uses a combination of two 12-cylinder V-type DB 601 DB 606 engines, and the A-5 model begins to be equipped with two DB 610 engines of the DB 605 combination. The two V-shaped combinations together are W-shaped, compact but complex, and the heat dissipation problem is more prominent. He 177 is prone to engine fire accidents, the main reason is that the engine compartment design is too small, heat dissipation is difficult.
DB 606 liquid-cooled engine
DB 610 liquid-cooled engine
So this flat-headed liquid-cooled engine layout was used until the end of the piston aircraft development, because aircraft like the Ta 152H and Do 335 were considered by many to be the ultimate propeller fighter.
So conversely, does the air-cooled engine have a pointed head? There certainly is, and more. Small-power air-cooled engines, the number of cylinders is also relatively small, the heat dissipation problem is not so prominent, made into a single row in-line or V-shaped large people. With a slight fit of the bonnet, you can get a pointed tip, such as the following two models that we are familiar with.
Surviving Fi 156 Stork Liaison Machine
Surviving Bf 108 trainer/liaison
Both aircraft use 8-cylinder V-Type As 10 air-cooled engines, with different models of power ranging from 200 to 240 horsepower.
As 10 air-cooled engine
It is also possible to mention it further, such as the following ones.
Fw 189 reconnaissance aircraft
The Fw 189 is equipped with a 12-cylinder V-Type As 410 air-cooled engine with 450 hp
French CR.714 light fighter
The CR.714 uses a Renault 12R 12-cylinder inverted V-type air-cooled engine with 500 hp
American Curtis Seagull MK.I reconnaissance aircraft (SO3C-1) used by British Fleet Aviation
The SO3C is equipped with a Ranger V-770 inverted V-12-cylinder air-cooled engine with 600 hp
Italian SAI.207 light fighter
The SAI.207 is equipped with an Isota Flasini Delta 12-cylinder inverted V-air-cooled engine with 750 hp
In fact, the in-line V-type aero-cooled engine is relatively rare to the Delta level. For example, the previous Photo of the Renault 12R is actually a special type, and the power is also 750 horsepower, while the Delta series can reach a maximum power of 900 horsepower. But at this time, the practicality is greatly deteriorated, or the heat dissipation problem we have repeatedly mentioned before, almost impossible to solve. The 900 hp Delta was mounted on the Re.2001 prototype, but due to heat dissipation problems, the whole machine was burned down, and it was easily defeated by the German DB 601 liquid-cooled engine, which was also a 12-cylinder inverted V.
But the Italians may be really tough on this side, and they have to go to the end of the inline high-power air-cooled engine. At that time, the Italian aviation industry urgently needed to compete with an air-cooled engine of more than 1,000 horsepower and an imported German liquid-cooled engine, especially the DB 605. So Isotta Flassini combined two 550 hp 12-cylinder inverted V-type Gamma engines to produce a 24-cylinder X-type Zeta, with an estimated power of 1200 hp, and the aircraft was selected as the Caproni Vizzola F.6Z (Z refers to Zeta).
12-cylinder inverted V-type Gamma
24-cylinder X-type Zeta
Caproni Vizzolla F.6Z
As a result, Zeta was built with serious heat dissipation problems, and it was not until August 1943 that the first flight was installed, and the F.6M carrying the DB.605 was first flown for two years. Italy surrendered in September 1943, what else is going on? So the Italians' dilemma in aero engines during World War II may have been caused by the fact that they had to drill on them.
This form of high-power air-cooled engine has also been developed in other countries, such as the X-4520 built by the American Allison Company in 1927, which is also an X-type 24-cylinder air-cooled engine with a power of 1200 horsepower, and it is also unable to solve the heat dissipation problem and is abandoned. The Exe, built in 1936 by the British company Rolls-Royce, is also an X-type 24-cylinder air-cooled engine with a power of 1150 horsepower, and it is said that it performed well in test flights, but it was not put into production. It seems that they have encountered the same congenital problems, which cannot be solved in the 20s and cannot be solved in the 40s.
Allison X-4520
Rolls-Royce Exe engine
Well, that's all this time. Because it is to find a special case, it will certainly not be comprehensive. You can also pay attention to which aircraft at that time were equipped with air-cooled engines that looked like liquid-cooled or liquid-cooled engines that looked like air-cooled.
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