Guide to Manual Engine Controls (MEC)

The Purpose of Manual Engine Controls

"Manual Engine Controls" are the direct control by the player over the numerous controls 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. First of all, one needs to set a key to toggle these engine controls to "manual" mode.

Controllable Elements

Ignition and engine selection

An engine won't function without being turned on, of course. For turning an engine on, the default key is "I". This will start an engine when it's off and vice versa. 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.

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 are 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, 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, leading to some loss in performance.

When the engine temperature is too hot (the temperature indicator in the HUD will appear yellow, then orange, then red and finally, flashing red), opening the radiator to higher than 50% is the best choice, 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 fully open while warmer maps do the opposite. A damaged cooling system means that the pilot will have to handle their aircraft more gently. Don't forget that prolonged engine overheating will lead to the loss of said engine.

Propeller Pitch

The propeller pitch is the angle at which the blades of a propeller operate. Prop control leaver is used to set desired pitch. The propeller pitch influences prop efficiency which changes vastly with airspeed. Low prop pitch means that blades are set at low angle, the drag of rotary movement is weak, thus they can reach high rpm. At low air speeds this setting gives proper angle of attack of the blades to produce thrust. When no adjustment is made, blades angle of attack decrease with increasing a air speed, so that lesser and lesser thrust is being produced. It means that higher pitch is required. The higher the pitch, the more efficient prop is at higher air speeds, 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 constant speed propellers such as in most War Thunder aircrafts, 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 corresponds to low pitch (high rpm) and full aft position corresponds to high pitch (low rpm) or "feathered" when applicable.

Not all propeller-driven aircraft in War Thunder have the option to control the propeller pitch manually, since many have an automatic system for this matter. These are more commonly found in German, Italian and/or late war planes. This can be switched to manual control, but is not advised due to most automatic systems using an RPM limiter to prevent over-rev. As an example, a Bf-109 (F-series onwards) will over-rev when prop pitch is more than ≈60% while throttle is at 100%, but will never over-rev when automatic control is enabled.

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 immediate 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.

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 and feathering its propeller is the best choice in order to reduce drag and maintain flight.

Mixture and throttle management

An 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 altitude, such as 8500m, 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 1km, as it was designed mostly for difficult takeoffs and landings, as well as a "WEP" in certain scenarios.

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'.

• Turbos

Turbos are currently auto-regulated in War Thunder, which is historic in most applications. Turbos are used almost exclusively on USAAF aircraft intended for high-altitude use (P-38, P-47, B-24, B-17, and B-29). Turbochargers add significant weight and complexity to an aircraft, but it pays dividends at altitudes above 18-20k feet where the efficiency of turbos outperform traditional, mechanically driven superchargers.

• 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 stahes should be changed (if present or modeled 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.

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 "Heimatschützer" series. In these aircraft, the rocket booster is an engine that adds immensely to the aircraft's 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.

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/