Suppose, just suppose, we were to pit the best propeller-driven fighter from the Second World War and the best modern jet fighter currently available against each other.
Would the outcome be a forgone conclusion? Or would the propeller plane have at least a fighting chance?
The answer, it turns out, might actually surprise you.
Why were propeller aircraft replaced with jet aircraft?
The short answer is they weren't, at least not completely. Propeller aircraft are still commonplace today, albeit in more specialized roles.
A full discussion on the differences between these two types of engines is far beyond the scope of this article, but we'll attempt to make a quick and dirty comparison for brevity.
As a general rule of thumb, jet engines are best for longer journeys, or journeys that need to be made quickly. Propeller-driven aircraft is best for small smaller or light aircraft where fuel capacity and profitability of operation is limited. Another unofficial metric is the number of seats an aircraft has.
If under 100, or so, an aircraft will often have a turboprop engine. Above that and it is probably equipped with jet engines.
When it comes to military aircraft and commercial airliners, for the most part, jet engines have pretty much completely replaced propeller-based aircraft. This is for a variety of reasons, but the increased speed that is afforded to jet-engined aircraft is one of the most important reasons.
Another benefit of jet engines is their ability to operate at higher altitudes when compared to propeller-driven aircraft. This, combined with their greater speeds, makes jet engines the engine of choice for long-distance travel — like taking you on a holiday.
Propeller-driven aircraft also require less runway distance to take off and land and can handle a variety of runway constructions, unlike jet engines. For this reason, regional airports or airfields that might not have concrete runways will likely exclusively only handle propeller-driven aircraft rather than jets.
Propeller-driven planes are also more fuel-efficient for shorter flights, have lower running costs, are cheaper to insure, and are generally cheaper to maintain than jet engines. However, jet engines are, believe it or not, much quieter engines to run, which makes them better suited for airports near residential areas.
However, modern jet engines, most commonly the turbofan engines of today are something of a hybrid between the two engine types. In a turbofan, some air comes in the front, is compressed and mixed with fuel, which is then ignited.
The hot exhaust passes through the core and fan turbines and out of a nozzle, as in a turbojet. The rest of the incoming air passes through the fan and goes around the engine, like the air through a propeller. The air that goes through the fan has a higher velocity, from the free stream. So a turbofan gets some of its thrust from the core and some of its thrust from the fan.
All of this takes place inside the shell covering of the engine, which produces a duct through which the air can flow smoothly.
The aforementioned fan is made of many tiny blades that act as a kind of propeller.
There are also propeller engines called turboprops that are, in effect, a propeller turned by a jet engine rather than a piston-engine, as in more traditional aircraft. These kinds of engines are very reliable and efficient, and also help make up some of the noticeable difference in speed between propeller engines and jet engines.
So, in a sense, since the 1950s, rather than completely replacing propeller-driven engines, jet engines have, to a greater or lesser extent, joined forces with their more traditional counterparts.
All very interesting, but in a hypothetical death match between a propeller-driven aircraft from the 1940s and a modern jet, what would the outcome be? Apart from the inherent differences in engine capability, modern fighters have some distinct advantages over their old compatriots. One is their common use of heat-seeking missiles.
But, would they be of any use against a propeller aircraft? Let's find out.
How do heat-seeking missiles work?
More correctly termed infrared homing missiles, "heat-seeking" missiles are basically special rockets with a passive weapons guidance system that relies on infrared emissions to target and track vehicles like aircraft or tanks. Heat sources, like an aircraft's engine, kick-off a lot of infrared, hence the more colloquially used name "heat-seeking".
Such missiles are able to recognize the temperature difference between objects and so can easily detect the difference between an airframe that is above ambient temperature and its background, like the sky. (Later passive air-to-air missiles homed in on ultraviolet radiation as well.) Using this temperature difference, the "heat-seeking" portion of the missile is able to target and guide a missile towards its target.
We'll talk a little about the association between "hot" bodies and infrared light in a moment, but many things give off infrared light, including your own body, vehicle engines, etc. This phenomenon makes them stand out from the background. If a method can be found to home in on this kind of light energy, then weapons, like missiles, can self guide themselves without the need for human control.
"Heat-seeking" missiles, being passive systems, do not have a transmission that can be easily "tracked" by potential targets, making such weapons very difficult to spot and disable until it is too late. This is in contrast to more active targeting systems like radar-guided weapons, for example.
While modern military aircraft are fitted with special suites of sensors and cameras called Missile Warning Systems (MWS), such systems are only really able to optically detect a missile at range. While better than the human eye, they are not completely effective and are subject to false positives and false negatives.
Another way to indirectly warn of potential incoming "heat-seeking" missiles are sensors used to detect radar locking. Called a Radar Warning Receiver (RWR), these systems can provide a pilot with a warning they are being targeted, but do not actually detect the missile itself.
"Heat-seeking" missiles are extremely effective weapons systems, with the vast majority of United States aircraft losses from infrared-homing missiles alone. However, like most weapons systems, they are not 100% foolproof.
Some fairly simple countermeasures can be employed to throw them off course and protect the target aircraft. For example, flares can be released behind the aircraft to provide false heat sources for these kinds of missiles to lock on to and "destroy".
However, such countermeasures are only effective if the pilot of a target aircraft is aware that their aircraft is currently under threat from IR-homing missiles. Some countermeasure systems, such as planes that emit fields of IR radiation, are also able to automatically deploy too.
More modern IR-homing missiles are also subject to increasing complexity to make them "smarter" against such simple countermeasures.
Interestingly, this technology is actually pretty old. Some of the first infrared devices were experimented with during the Second World War, for example. These early devices were devised by German engineers who developed rudimentary heat-seeking missiles and proximity fuses.
Thankfully, from the Allied point of view, the war was ended before the Germans could make significant breakthroughs in this technology.
True "heat-seeking" missiles did not become possible until the 1950s, when rocketry technology, conical scanning, and miniaturized vacuum tubes become sophisticated enough to be integrated together on a missile platform. These early missiles — while technologically impressive for the times — were unreliable and achieved low success rates in the 1960s.
The technology underwent significant development throughout the 1970s and 1980s to make them highly effective weapons systems. More contemporary units are very sophisticated and have the ability to attack targets out of their field of view (FOV), coming up from behind, and even to pick out vehicles on the ground.
In modern missiles, the infrared sensor package tends to be located in the tip or head of the missile and is known as a "seeker head".
Most "heat-seeking missiles" come in a variety of types, depending on their sensitivity to infrared light. Early ones, now called single-color seekers, were most sensitive to infrared light between the 3 to the 5-micrometer range. These kinds of missiles proved to be relatively ineffective, as they would often only be effective so long as the missile could "see" the jet exhaust of an enemy aircraft.
This led to the development of new missiles, called "all aspect" that were sensitive to the exhaust as well as the longer 8 to 13-micrometer range. For reference, a human body emits infrared light at around the 12-micrometers range.
Such missiles are also able to lock on to dimmer heat sources on an aircraft, such as its fuselage. They also tend to require cooling to give them a high degree of sensitivity to allow them to lock on to the lower level signals from the sides and front of an aircraft in flight. Modern "all-aspect" missiles such as the famous AIM-9M Sidewinder and Stinger use compressed gas like argon to cool their sensors, in order to lock onto the target at longer ranges and all aspects.
Similar technology is also employed in semi-automatic command to line of sight (SACLOS) technology. In this kind of setup, the IR seeker is mounted on a trainable platform on a missile launcher that is operated by a human user.
The user will manually point the weapon in the general direction of the target manually. The seeker will then not track the target but the missile itself which is then guided by flares to provide a clean signal. Some other systems will use radio signals to guide the missile towards the target in the user's aiming telescope.
These kinds of weapons have commonly been used for both anti-tank missiles and surface-to-air missiles, as well as other applications.
Why do "hot" things emit infrared light?
As promised, we'll now discuss why "hot" things emit infrared radiation. Before we start, take a moment to think about the Sun.
The Sun transmits energy to Earth at different wavelengths of the electromagnetic spectrum. All forms of electromagnetic radiation transmit energy, and heat is simply the transfer of kinetic energy from one medium, or object, to another.
Much of the harmful ultraviolet radiation is absorbed by the Earth's ozone layer, but visible light and shortwave infrared light passes through much of the atmosphere. This energy reaches the surface of the Earth and is absorbed.
The Earth's surface emits longwave infrared energy (heat) back to the atmosphere. Some of this escapes to space, but a significant portion is absorbed by Greenhouse gases or clouds. The gases or clouds, in turn, emit heat back to the surface or into the atmosphere. This emitted radiation adds to the surface warming from sunlight.
For all other heat sources on Earth, most of this kinetic energy transfer occurs within the infrared part of the electromagnetic spectrum. The reason for this is a little beyond the scope of this piece, but it has to do with black body radiation.
All objects with a temperature above absolute zero (0 K, -273.15 oC) emit energy in the form of electromagnetic radiation. A perfect black body, according to Kirchoff's law of radiation, would be one that absorbs all light in all frequencies all the time (hence being called a perfect black body). Such a body would also emit light with maximum efficiency in all wavelengths. It is a hypothetical object which is a “perfect” absorber and a “perfect” emitter of radiation over all wavelengths.
However, this is a purely theoretical object. Most stuff in real life is somewhere between a perfect black body and a white body (a hypothetical object that absorbs no electromagnetic radiation of any wavelength).
All things with mass are made of atoms that are constantly in motion, or vibrating, if you'd prefer. The hotter an object is, the more violently and frequently this occurs. This vibration releases electromagnetic waves that, for most objects we can see, are in the infrared spectrum.
A campfire, for example, emits different wavelengths of light, but the vast majority of the "heat" comes from the infrared light it emits.
In fact, if you were to place a special filter between yourself and the campfire that only allows infrared light through, it would feel just as hot to you. Such light is invisible to your eyes, but can be detected using special cameras that, depending on the way information is displayed, can make things look like they are glowing.
To make infrared images, we can use special cameras and film that detect differences in temperature, and then assign different brightness, or false colors to them. This provides a picture that our eyes can interpret.
Typically, when using an infrared camera, hot things look bright yellow and orange. Items that are colder, such as an ice cube, are purple or blue.
Most bodies radiate most of their heat in the infrared spectrum, because they don't have enough energy (heat) to radiate at a higher frequency. Any object that has a temperature will release infrared light to a greater or lesser degree including, as we've previously mentioned, your body or a running engine.
Incredibly, even objects that we think of as being very cold, such as an ice cube, will emit some infrared light. This is because, although it is "cold" to us, the atoms within an ice cube are still vibrating and releasing infrared radiation.
Any object that does not quite have enough thermal energy to radiate visible light will still emit energy in the infrared.
Take, for example, hot charcoal. This may not give off much visible light but it does emit infrared radiation which we feel as heat. In fact, the warmer the object, the more infrared radiation it emits.
For this reason, infrared radiation makes an excellent indirect way to record the relative temperature of an emitting object from a distance.
Some animals have even evolved natural infrared detectors of their own too. Take the pit viper family, for example.
Like other members of the 'pit viper' (Crotalinae) family of snakes, as well as members of the boa (Boidae) and python (Pythonidae) families, they have evolved special sensory "pits" that are able to detect infrared light. This allows the snake to detect warm-blooded animals from a distance, enabling the snake to hunt these creatures. It is even thought that snakes armed with pairs of sensory pits are able to have a rudimentary form of infrared-based depth perception.
From the perspective of this piece, jet engines might not give off a lot of light (apart from the exhaust gases) but they do produce a lot of infrared light. They are, after all, very hot things.
This is something that can be used to detect and track.
Could a heat-seeking missile track and destroy a WW2 fighter?
Not to sound too flippant, but the answer to this question is a definite... maybe. It all depends on the target aircraft in question, and the kind of missile launched.
Early "heat-seeking" missiles would likely struggle to find the infrared signature of an old propeller-powered plane and maintain a lock. This would especially be the case if the target plane had some countermeasures, like flares.
This is because a typical jet engine will burn at around 3,632 degrees Fahrenheit (2,000 degrees Celsius). While modern jets will also tend to have some form of cooling mechanism to prevent engine part wear, the exhaust and engine cowling will typically be around 1,832 degrees Fahrenheit or more (1,000 degrees Celsius). A piston-engine, on the other hand, is cooler — typically around 572 degrees Fahrenheit (300 degrees Celsius), give or take.
Flares, especially those used as countermeasures, tend to be made primarily of magnesium, which burns at somewhere in the region of 3,632 degrees Fahrenheit (2,000 degrees Celsius). This would likely confuse a heat-seeking missile, allowing the piston-engine aircraft to escape.
Flares aside, for more modern IR-seeking missiles, like a Sidewinder, it should be quite possible. In fact, it has even been done before.
During the development of the AIM-9 Sidewinder missile, it was tested against a variety of targets, including an old Grumman F6F "Hellcat" piston-powered, propeller drone aircraft.
Despite the distinctly smaller heat signature generated by the F6F combustion engine, the missile was able to lock on, track, and destroy the aircraft with little trouble.
For a piston-engined aircraft, the largest heat source is, from an IR sensors' point-of-view, the engine cowling and exhaust. The airframe can also give off its own heat signature in flight, from friction with the air, but this is less pronounced on slower flying aircraft when compared to say a jet.
Modern missiles are even able to lock on to and track the leading edges of the wings of some aircraft that tend to "heat" up as a consequence of frictional heating and ambient heating. In fact, the IR-seeking detectors on modern missiles are so sensitive they are thought to be able to lock on to a human body (albeit at close range).
IR-missiles would possibly struggle, however, if the target piston-engined aircraft heat signature was obscured by the weather (like clouds), if the aircraft was flying in front of the sun, or if the missile approached from above (i.e. so the ground is the backdrop to the plane).
This is why, as we previously mentioned, most modern missiles have mechanisms to cool their seeker head prior to firing, using nitrogen or some other method, that gives a much greater contrast between the target and its background.
So, if the missile in question was the early 1950s or 1960s era kind, it may struggle to target and destroy a WW2 piston-engined aircraft. If it were a more modern form of missile and the WW2 plane were not equipped with flares, it shouldn't have an issue.
All well and good, but how would a modern fighter compare to a WW2-era fighter in a dogfight? Let's find out.
Could a modern jet destroy a WW2 fighter in a dogfight?
A dog fight, with respect to aerial combat, is an aerial battle between fighter aircraft conducted within gun range. While relatively rare today, it was the pre-eminent method of engaging enemy aircraft throughout most of the pre-air-to-air missile era of aerial combat.
One of the first recorded instances of a dogfight took place during the Mexican Revolution in 1913, shortly after the invention of the airplane, and would remain a relatively common method of engagement until the early-1990s.
Termed air combat maneuvering (ACM) in modern military parlance, the term has been used to describe a melee or fierce, fast-paced, close-quarters fight. It became popularized in WW2 but was first coined during WW1.
While pilots are still trained in dogfighting maneuvers today, the primary focus of their training is for a term called "beyond visual range air-to-air combat" (BVR). Combat at this range involves the use of long-range radar-guided missiles like the AIM-12 AMRAAM.
In fact, dogfights, as most people would understand them, are not really relevant to aerial combat today. As one United States pilot, Lt. Col. David "Chip" Berke pointed out in an interview with Business Insider.
"The whole concept of dogfighting is so misunderstood and taken out of context," Lt. Col. Berke explained. "We need to do a better job teaching the public how to assess a jet's capability in warfare."
"There is some idea that when we talk about dogfighting it's one airplane's ability to get another airplane's 6 and shoot it with a gun ... That hasn't happened with American planes in maybe 40 years," Lt. Col. Berke added.
That being said, dogfights have been seen in some fairly recent aerial engagements. Famously, British Harrier Jump jets engaged Argentian aircraft at close quarters fairly regularly during the Falklands War of 1982.
One of the last events involved Royal Airforce pilot David Morgan, who was able to destroy two Argentinian jets on June 8th, 1982. More recently, in 1996, Turkish and Greek aircraft were involved in clashes over the Aegean Island of Chios.
After a fairly prolonged dogfight (here's some actual footage), a Greek Mirage 2000 (piloted by Thanos Grivas) was able to shoot down a Turkish F-16D twin-seater. Another example occurred in 1999 when a pair of Ethiopian Su-27SK's engaged four Eritrean MiG-29As.
Three of the Eritrean fighters were shot down, with no losses on the Ethiopian side. It should be noted that this engagement is hotly debated, and probably involved short-range missiles rather than guns.
All well and good, but could a modern jet easily destroy a WW2-era fighter in a dogfight? That question is not as easy to answer as you might expect.
Firstly, jet fighters are considerably faster than piston-engined aircraft. While modern aircraft, fifth-generation onwards, tend to be very maneuverable, they can only fly at slower speeds for a limited time without stalling.
This is typically between 100 knots (115 mph - 185 km/h) and 200 knots (230 mph - 370 km/h). It is important to note that the stall speed of a fighter jet is not a fixed value, it continuously varies during a flight depending on the flight parameters, primarily, the angle of attack.
That being said, modern jets have a complex suite of electronics that constantly monitor flight parameters in order to predict, and often automatically make adjustments, to prevent a stall. While they can fly at the speeds needed for a classic dogfight against a WW2-era fighter, there are significant limitations to this.
Piston-engined aircraft, especially from the WW2 era, typically have a top speed of around 400 mph (640 km/h). This does vary depending on the aircraft in the question, of course. Some were much faster, like the incredible German Dornier Do 335 (top speed of 474 mph/846 km/h) or the British Supermarine Spiteful (top speed of 485 mph/780 km/h).
Interestingly though, dogfights did occur between jet-engined aircraft and traditional piston-engined aircraft during WW2. Towards the end of the war the first-ever jet fighter, the Messerschmitt Me 262 became operational and was swiftly brought to bear against Allied bombers (and their escort fighters) in a desperate fight to defend Germany.
And their impact was pretty devastating. The aircraft officially entered service in April of 1944 but Me 262 pilots are believed to have shot down well over 500 kills in just over a year.
As President Dwight Eisenhower pointed out in a secret report in 1960:
"During that time the Germans literally flew rings around our fighters and bored holes in our bomber formations with complete impunity... For example, 14 fighter groups escorted the 1,250 B-17 raids on Berlin on March 18  — almost a one-for-one escort ratio. They were set upon by a single squadron of ME 262's which knocked down 25 bombers and five fighters, although outnumbered roughly 100 to 1. The Germans lost not a single plane."
The aircraft was around 100 mph (160 km/h) faster than the best the Allies had to offer, which gave them a distinct advantage. However, Allied pilots came up with some innovative strategies to deal with this new high-tech threat.
For example, like most aircraft, the Me 262 was most vulnerable while taking off or landing. It was in this prone state that most Me 262 combat losses occurred.
In the air, however, things were a very different story. Allied pilots quickly learned that the new jet fighters, while impressive, had some serious weaknesses.
For example, Me 262 pilots could not throttle their engines too quickly or they would suffer a flameout. As most Me 262 pilots were also just getting used to their aircraft, they proved to have poor maneuverability at low speeds. They also had limited time in the air compared to piston-engined aircraft, which limited their ability to dogfight.
For these reasons, Allied pilots would goad Me 262 pilots into engaging them at slow speeds. Amazingly, there is even some existing footage of one such engagement. There are also some amazing stories of American aces who were able to go toe-to-toe with a Me 262 and come out the victor.
But these events were very much the exception to the rule. The jet age had officially begun.
Modern jet fighters also have the advantage of sophisticated targeting systems to guide their guns. This is usually displayed in a pilot's Heads-up Display (HUD) and data collated by a Lead Computing Optical Sight or Enhanced Envelope Gun Sight (EGGS).
Both of these systems provide the pilot with a projected fall of shot from their guns from the aircraft's speed, angle of attack, and other variables. This is clearly a massive advantage over older the more basic gunsights of WW2-era fighters.
With regards to more modern jets, there is an interesting experiment that is well worth noting. In 1979 a film called "The Final Countdown", some scenes show a dogfight between a pair of Grumman F-14 Tomcats and a pair of WW2-era Japanese Zeros.
While the F-14s appear to have very little trouble dealing with the Zeros, the amazing part is that the footage was actually recorded for real. No CGI existed at the time, and so the pilots were really doing the mock dogfight.
However, the F-14, being a variable swept-wing aircraft gave it some more options when compared to fixed-wing aircraft.
All very interesting, but are we able to make a prediction at this point?
We believe so. Modern jet fighters are much faster than earlier jet fighters, like the Me 262. They are also far more reliable than earlier jets and their pilots are far more experienced.
So, if we were to take two ace pilots flying aircraft they are most comfortable in, the outcome would likely be a foregone conclusion.
Since most air-to-air victories are won when the defender is unaware of the attacker, a jet-engined fighter should be able to seek and destroy their piston-engined opponent long before the other is even aware of the danger.
While there might be some scenarios in which the piston-engined aircraft could catch the jet fighter by surprise, the suite of sophisticated sensors on the jet fighter would make this very unlikely.
That's if, of course, unless the piston-aircraft isn't already a burning wreck from a missile hit fired from miles away.