Guide to Manual Engine Controls (MEC)

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The Purpose of Manual Engine Controls

"Manual Engine Controls" (often abbreviated as MEC) are the ability for a player to manually control multiple components of an engine. Used properly, these allow for greater speed, fuel efficiency, engine cooling and management of a damaged engine. These take a bit to learn, being left by default to the game to handle automatically, but are worth learning to gain an advantage. First however, a key must be set to toggle these engine controls to "manual" mode. This can be found in Full-Real Controls under the Aircraft category. Once bound, MEC can be used with any control scheme by pressing the bound button.

Controllable Elements

Ignition and engine selection

An engine won't function without being turned on, of course. To start or turn off an engine, the default key is "I" and is available on all aircraft, independent of MEC settings. The throttle controls are separate from the ignition; an engine that is off won't work, even if the throttle is at 100%, whilst an engine that is turned on but at idle throttle will spin its propeller (albeit very slowly, outputting very little power). Sometimes it is important to shut down an engine mid-flight. For instance, if your aircraft is set ablaze, turning off the burning engine will cut the fuel from pumping into the burning engine, potentially extinguishing the fire. Shutting an engine down will also rapidly cool it down, but this is inadvisable except when it is certain no enemies are around.

Engine selection is used to select one specific engine at a time or all engines at once. This allows for the selected engine to be controlled using all other MEC inputs, ignoring them for other engines. Engine selection is rarely used on single-engine aircraft, as the main engine is always selected, but can find use on aircraft with multiple engines, such as the B-17 and Mosquito. Here it becomes useful for managing a damaged engine or destroyed engine, possibly allowing the plane to limp back to the base where it otherwise couldn't. Remember to reselect all engines when needed.

The Radiator

The radiator's purpose is to keep the engine cool. Essentially, the radiator is a series of snaking tubes that take the hot engine coolant, pass cold air over it to cool it down, and pass it back into the engine cooling it down. The controllable aspect of a radiator is the cowl flaps, labelled as 'radiator' in the game's controls. Setting the radiator to 0% means closing the flaps, whilst setting it at 100% means having them fully open. These, while open, allow an influx of air to enter the cooling system of the plane, reducing the engine temperature. However, opening the cowl flaps leads to increased drag in the surface of the aircraft, hurting performance in regards to dive rate, energy retention and straight-line speed. Whilst performing a sustained climb, the power-to-weight ratio is the most important aspect of the aircraft, thus the increased drag from open cowl flaps is rather harmless. When speed is the top priority, closing the cowl flaps to increase speed is a reasonable choice. When climbing at the start of a match, without the pressure of a dogfight, opening the cowl flaps to 100% to avoid overheating is recommended, but some planes will be able to climb needing only a partially opened radiator, reducing performance loss from drag.

When the engine begins to overheat, the temperature indicators on the HUD will appear yellow, then orange, then red and finally, flashing red, after which engine damage will take place. Opening the radiator will help reduce overheating, bringing the temperature down and preserving engine life. It is recommended to keep the temperatures in the yellow or orange zone, save for emergencies, where losing speed means losing a fight and consequently, the plane. Each plane has its own thermodynamic characteristics, so it takes a bit of practice to know how to handle the radiator efficiently. Remember that more speed and altitude affect the effectiveness of the cooling system positively, whilst running at high throttle settings increases the heat the engine emits. Cold maps reduce the need for radiators being open while warmer maps do the opposite. A damaged cooling system means that the pilot will have to handle their aircraft more gently. However, leaving a damaged cooling system unattended for extended periods will slowly cripple the plane's engine, and is advisable to return to base for repairs ASAP.

The majority of planes have full manual control for their radiators, with some notable exceptions. Full manual control in this scenario means the player having to manually both the oil radiator and the engine/water's radiator when switching to MEC. Most biplanes do not have any form of radiator control relying on throttle and propeller pitch (if they have it). Planes such as the Spitfire Mk I(Spitfire Mk IIa) and Spitfire Mk Vb only have radiator controls for the engine itself or water, leaving the oil to be passively cooled or automated. Others such as the Bf-109 F series onwards and some late-war planes have fully automated radiator control when switching to MEC, but can be changed to manual control by a button toggle. Jets do not use radiator control.

Both oil and standard radiator will default to 50% when MEC or manual mode is enabled. The last set manual setting is saved when toggling back to auto mode and will be set to that when re-toggling to manual mode.

For extended reading on engine temperature, see the Thermodynamics page.

Propeller Pitch

The propeller pitch is the angle at which the blades of a propeller operate. Prop control lever is used to set the desired pitch. The propeller pitch influences prop efficiency which changes vastly with airspeed. A low prop pitch means that blades are set at a low angle, the drag of rotary movement is weak and can reach high RPM. At low airspeeds, this setting gives a proper angle of attack of the blades to produce thrust. When no adjustment is made, blades angle of attack decrease with increasing airspeed, so lesser thrust is produced. It means that the higher pitch is required. The higher the pitch, the more efficient prop is at higher airspeeds, which means that low prop pitch generally means better performance at low speeds, whilst at high speeds, low pitch not only generates drag but can also lead to engine failure from over-revving the engine. One can be easily confused as low pitch implies high rpm and vice versa: high pitch generally implies low rpm. In variable-pitch propellers that most War Thunder aircraft have, the general rule of operation is to have low pitch (high rpm) at low speeds and high pitch (lower rpm) at high speeds. Prop control in full forward position (or 100% pitch in the game) corresponds to low pitch (high rpm) and full aft position corresponds to high pitch (low rpm) or "feathered" when applicable.

Propeller pitch needs to be set as a relative control, or else the pilot will be alternating between 0% and 100%, which is nonsensical, inefficient and may lead to over-rev in some cases. In aircraft that have no 'feathering' option, such as most fighters, setting the propeller pitch to 0% when the engine is dead helps to keep the plane gliding. Setting to 0% will also consume less fuel and reduce engine overheating. On most planes with manual control for propeller pitch, setting the prop pitch to 90-100% will allow for maximum performance at combat speeds while 70-80% allows for fuel-efficient cruising and diving with less drag. Some planes will require different settings, however.

Not all aircraft in War Thunder have the option to control the propeller pitch manually. Some have an automatic constant-speed system which can be switched to manual mode while others have a fixed pitch. Most biplanes and interwar planes use a fixed pitch propeller, allowing no manual prop pitch control. Jets also do not use propeller pitch. Automatic constant speed systems are often found in German, Italian and/or late warplanes as well as some others. The system can be switched to manual control, but is heavily inadvisable without prior knowledge, especially with German planes. This is due to the constant-speed governor being disabled, possibly allowing the propeller to over-rev from high RPM. As an example, a Bf-109 (F-series onwards) will over-rev when prop pitch is more than ≈60-65% in manual mode while the throttle is at 100%, but will never over-rev when automatic control is enabled. Over-rev does not occur on all planes with a constant-speed governor. Conversely, prop pitches that would over-rev can be used very effectively as an airbrake if the throttle is reduced properly, being even more effective than purpose made airbrakes in some cases, but this requires some experience to prevent said over-rev.

Propeller pitch defaults to 50% for all propellers when MEC or manual mode is enabled. The last set manual setting is saved when toggling back to auto mode and will be set to that when re-toggling to manual mode.

Propeller Feathering

Under the "Manual Engine Controls" tab in the "Full Aircraft Controls" tab in "Controls", the option "Prop Feathering" is present. The button assigned to this control will rotate the propeller's blades until they are positioned parallel to the airflow, reducing drag substantially. This should be done when an engine is inoperable, enabling the aircraft to fly more efficiently with less drag than an ill-positioned propeller. In multiple-engined aircraft, it is very common to lose an engine to a fighter, and thus selecting the damaged engine with the engine select key and feathering its propeller is the best choice in order to reduce drag and maintain flight.

Mixture and throttle management

A piston engine works by combusting fuel with air in its pistons and requires an optimal ratio of the two to function properly. This applies to all piston-engined aircraft in War Thunder. However, there are many aircraft that do not give their pilots an option for mixture control, as some aircraft were built with automatic systems for this. It is worth learning how to manage the fuel mixture since the automatic management of mixture in War Thunder by the AI isn't perfect and does not always correspond to a pilot's intentions. A mixture setting with a high fuel-air mixture is considered "rich" while a low fuel-air mixture is considered "lean".

As the altitude changes, the optimal mixture changes too; the greater the altitude, the lower the presence of oxygen and density of the air (as such, the air intake decreases). This means that the pilot will need to increase the air in the mixture (making it "lean"). In War Thunder, fuel mixture is displayed as a percentage - to have a more fuel-rich mixture, useful for top performance at lower altitudes, the pilot sets the mixture to a number close to 100%, whilst to achieve a mixture with more air in it a much lower mixture is used (however, setting it at 0% little more than starve the engine and cut it). When at high altitudes, such as 8,500 m, a pilot may be using a mixture setting close to 40%. It is possible for some planes to achieve a mixture of up to 120%. This should only be used at altitudes of less than 1,000 m, as it was designed mostly for difficult takeoffs and landings, as well as a "WEP" in certain scenarios.

Most aircraft in the game can be left at the default 60% mixture and will fly without consequence. However, some such as the Ki-44-I and the P-47 require micromanagement of mixture to provide maximum thrust. Most German and Italian fighters use a completely automated mixture control which does not require or allow player input. Jets do not use mixture control.

Mixture defaults at 60% when MEC is enabled. The last set manual setting is saved when toggling back to auto mode and will be set to that when toggling to manual mode.

Turbo- and Superchargers

In aviation, the purpose of a supercharger is to provide additional oxygen required to maintain engine performance as the aircraft reaches thinner air at higher altitudes. There are two types of superchargers; mechanically driven, and exhaust driven - generally referred to as a turbocharger, or 'turbo'.

  • Turbochargers

Turbochargers are auto-regulated in War Thunder with the ability to be manually controlled, which is historic in most applications. Turbochargers are used almost exclusively on USAAF aircraft intended for high-altitude use such as the P-38, P-47, B-24, B-17, and B-29. Turbochargers add significant weight and complexity to an aircraft but pay dividends at altitudes above 18-20k feet where their efficiency outperform traditional, mechanically driven superchargers. It is not advised to use manual mode on a turbocharger, as doing so risks damage to it, reducing high altitude performance.

Turbochargers default at 0% when MEC is enabled, slowly increasing to a 50% default. The last set manual setting is saved when toggling back to auto mode and will be set to that when toggling to manual mode.

  • Mechanically Driven

Traditional superchargers (mechanically driven) usually have between 1 and 3 stages, each suited to perform at a specific range of altitudes, just like gears on a bicycle. The altitude that stages should be changed (if present or modelled in a specific aircraft) is unique to each plane. You can either research time-period aircraft manuals and find what altitudes these stages should be switched (assuming Gaijin modeled them correctly), or simply go into cockpit mode and look at the Manifold Pressure gauge(s) (again assuming Gaijin modeled them correctly), while switching stages to see which one provides the highest manifold pressure (power) at your current altitude. Also, don't forget to decrease stages as you descend in altitude. This can become second nature as you become more familiar with specific aircraft. Some aircraft have fully automated supercharger staging and do not require or allow player input.

Superchargers default at Stage 1 when MEC is enabled. The last set manual setting is saved when toggling back to auto mode and will be set to that when toggling to manual mode.

Rocket Booster/RATO

The "Ignite Booster" control is undefined by default, and a key must be bound to it in order to unlock the full potential of the Me-262 C-1a/2b "Heimatschützer" series. In these aircraft, the rocket booster is a liquid fuelled rocket(s) massively boosts thrust output. This will increase climb rate and acceleration very significantly, allowing a massive advantage over the enemy at the start of a match or in combat. These can be switched off with the same button, allowing its fuel to be conserved. The "Ignite Boosters" control also serves to ignite RATO (Rocket-Assisted Takeoff) boosters on some planes, since the functions are very similar.

Using MEC in RB

Plane-Specific Advice Examples

This section is unfinished.

Bf-109 (A-series to E-3):

  • Manual prop pitch requires constant micromanagement to prevent over-rev.
  • Full manual radiators, can be set anywhere from 50-100% to prevent overheat.

Bf-109 (E-4 and F-series onwards):

  • E-4:
    • Auto prop pitch, can be switched to manual control. Not advisable.
    • Full manual radiators, set to 80-100% when climbing to prevent overheat.
  • F-series onwards:
    • Auto prop pitch, can be switched to manual control. Not advisable.
    • Automatic radiators, advisable to toggle to manual control and set to 100% when climbing.

Spitfire Mk I/II:

  • Manual prop pitch, oil temperature relies on it. Set to 2550-2600 rpm at 100% throttle to prevent overheating.
  • Manual water radiator, can be set to 100% for the 1st minute when climbing or using WEP. Can be set to 0-10% if trying to cool down the oil using the normal throttle.

Additional information (links)

This page is to be built based on _SKYWHALE_'s guide on the War Thunder Forums. The guide is very complete, and the user has granted the permission via PM to use the guide. Link to the guide: http://forum.warthunder.com/index.php?/topic/223619-my-manual-engine-controls-tutorial-with-video-updated-147/