Performance Tables

For raw performance numbers click HERE to download figures for the MiG 15 and F86 variants.

Specific Power Curves

The specific power curves presented here have been produced by interrogating the MiG Alley flight model. As well as being used to check on the accuracy of the flight model, the curves can also be used to make comparisons between the aircraft involved in MiG Alley. It should be possible to develop a tactical plan before entering the cockpit.

Specific power is defined as the rate of change of specific energy and it is used to measure the ability of an aircraft to change its state. The idea of specific power was developed during the sixties as part of the famous Top Gun programme. In the early stages of the Vietnam War, USAF pilots were not doing as well as they did during the Korean War. Pilots were sent to the Top Gun School and results improved significantly.

Pilots were introduced to the concept of energy manoeuvrability. They learnt how to measure and manage energy during air combat. As these theories were not developed until the sixties, specific power curves do not exist for the Classic Jets of the fifties. The curves presented here are generated from the MiG Alley Flight Model.

The Equation

Specific Power (Ps) = v. (T - D) / W Where: T is thrust D is drag W is weight V is velocity

T, D, and W should all be in same units of force.

Velocity is usually defined in feet per second. This means that Ps is also in units of feet per second.

When the Ps = 0, the thrust balances the drag exactly and it is possible for the aircraft to sustain its conditions. A positive Ps can be used to either change the height or the speed of an aircraft, e.g.:

If Ps = 100ft/s and v = 600ft/s:

It can climb at 100 x 60 = 600 feet per minute
Or have an instantaneous accel. = Ps.g / v = 100 x 32.2 /600 = 5.4 ft/s/s

Click to continue . . .

MiG Alley

It is very important to realise that the Ps calculated is for a point condition. As soon as the altitude, weight or velocity changes, then a new Ps must be calculated.

A negative PS cannot be sustained. Either the velocity will drop or the aircraft will have to lose altitude.

The Lift Line

It is usual for the specific power curves to be bounded by the physical limitations imposed on the aircraft:

The left side is bounded by the lift limit line. The aircraft cannot generate sufficient lift to sustain a position on the left of this line. The top boundary is set by the maximum g that the aircraft can tolerate. The right boundary is set by the maximum speed that the aircraft can tolerate. For the classic jets the airframe was rated at 7g.

In fact there were reports of 10g being reached without serious consequences. This seems reasonable because a 50% tolerance is usually built into the figures. Inspection of the following curves shows that the aircraft are very much under powered and so the g limit is largely irrelevant when considering performance.

The classic jets were not capable of exceeding mach during level flight. There is then an invisible barrier to the right! The MiG was not capable of exceeding mach 1 even in a dive. However the Sabre could and so it is likely that at some very large negative Ps the curve will exceed the speed of sound.

For the Classic Jets, only the lift limit line has any practical significance and so it is the only one drawn in the following diagrams.

Go to Part V