So what is the real purpose of engine management in real life? It primarily breaks down to two reasons. Fuel efficiency and maintenance considerations. Fuel efficiency should be obvious. You will get a lot more range at a more efficient setting. Maintenance considerations are there to extend engine life and time between overhauls. People see a time limit on military power for a plane and assume that that means the engine will overheat or blow up if you run it longer than that and that’s not the case. Is modeling it that way really more accurate? We don’t model the maintenance considerations, you get a fresh plane each time out. Hopefully, we’ll at least be able to take some stabs in that direction with ToD, but that’s not exactly something you can replicate to great effect.
USE OF TAKE-OFF (MILITARY) POWER It is often asked what the consequences will be if the 5-minute limit at Take-off Power is exceeded. Another frequent inquiry is how long a period must be allowed after the specified time limit has elapsed until Take-off Power can be used. These questions are difficult to answer, since the time limit specified does not mean that engine damage will occur if the limit is exceeded. Instead, the limit means that the total operating time at high power should be kept to a reasonable minimum in the interest of prolonging engine life. It is generally accepted that high-power operation of an engine results in increased wear and necessitates more frequent overhaul than low-power operation. However, it is apparent that a certain percentage of operating time must be at full power. The engine manufacturer allows for this in qualification tests in which much of the running is done at Take-off Power to prove ability to withstand the resulting loads. It is established in these runs that the engine will handle sustained high power without damage. Nevertheless, it is still the aim of the manufacturer and to the best interest of the pilot to keep within reasonable values the amount of high-power time accumulated in the field. The most satisfactory method for accomplishing this is to establish time limits that will keep pilots constantly aware of the desire to hold high-power periods to the shortest period that the flight plan will allow, so that the total accumulated time and resulting wear can be kept to a minimum. How the time at high power is accumulated is of secondary importance; i.e., it is no worse from the standpoint of engine wear to operate at Take-off Power for one hour straight than it is to operate in twelve 5-minute stretches, provided engine temperatures and pressures are within limits. In fact, the former procedure may even be preferable, as it eliminates temperature cycles which also promote engine wear. Thus if flight conditions occasionally require exceeding time limits, this should not cause concern so long as constant effort is made to keep the over-all time at Take-off Power to the minimum practicable. Another factor to be remembered in operating engines at high power is that full Take-off Power (3000 rpm and 61 in. Hg) is to be preferred over take-off rpm with reduced manifold pressure. This procedure results in less engine wear for two reasons. First, the higher resulting brake horsepower decreases the time required to obtain the objective of such high-power operation. At take-off, for example, the use of full power decreases the time required to reach an altitude and airspeed where it is safe to reduce power and shortens the time required to reach the airspeed that will provide more favorable cooling. Second, high rpm results in high loads on the reciprocating parts because of inertia forces. As these loads are partially offset by the gas pressure in the cylinder, the higher cylinder pressures resulting from use of take-off manifold pressure gives lower net loads and less wear. Sustained high rpm is a major cause of engine wear. It requires more "rpm minutes" and "piston-ring miles" to take off with reduced manifold pressure. In addition to the engine wear factor, taking off at reduced power is comparable to starting with approximately one-third of the runway behind the plane. Therefore, full power should always be used on take-offs.
Contrary to what a lot of people think, we actually would like to see people use engine management. But not in some contrived only-in-the-sim-world setup. One of the main considerations for any WWII pilot was his fuel and we’ve always wanted that to be central in the game as well. I just haven’t done a good job with that. With the latest beta release, we’re really looking to get that where we’ve always wanted it to be.
