INTRODUCTION

Almost every flight sim' pilot with Internet access will have been aware of the multitude of message threads over past weeks generated by the Jane's F-15E simulation. Those discussions have focussed on comparisons between the real F-15E and the Jane's simulator model of the same aircraft. It is only natural that so many serious flight sim' pilots are interested in making real world comparisons, because that can lead to correct strategic and tactical decisions within the simulation. Unfortunately there is much confusion regarding the F15, its variants and their respective strategic roles and capabilities. So, before introducing the simulation, let's put this discussion on a firm foundation.

The F-15 was primarily designed to fulfil the offensive and defensive roles within a counter-air campaign, the strategic objective of which is simply to permit friendly ground or sea operations to proceed without prohibitive enemy interference, which in a nutshell, is air superiority. As an air superiority fighter the F-15 has reigned supreme!

Enhancing the roll of the F-15 to that of combat support and anti surface operations has involved dramatic modifications to what was an already significant air to ground capability and has led to the F-15E. It was intended that by enhancing the F-15 with new air to ground systems and avionics, including structural changes, extra pylons and conformal fuel tanks, the F-15E would also have all weather long-range interdiction capabilities.

It was further intended that by retaining its air to air systems, none of the F-15's already awesome air superiority and Beyond Visual Range (BVR) capabilities would be sacrificed. Jane's F-15 simulation has done a remarkable job in modelling those avionics and weapon systems. In being faithful to the strengths of the aircraft, it has brought the art of Air to Ground combat to the flight sim' pilot with a new level of realism. However, in this article I intend to focus on aspects of the Jane's F-15 sim' dominated by the Within Visual Range (WVR) Air-to-Air engagement.

REAL WORLD COMPARISONS

Despite the admirable efforts of developers, simulations of modern air combat will always suffer from the lack of important classified data required for truly accurate modelling. Of course some degree of fidelity to the real world aircraft is possible because a lot of information can be easily obtained, but for aircraft still in service, where lives may depend on the security of classified data, what is available is unlikely to be complete, and may possibly be inaccurate.

Furthermore, the most publicly available data is not always typical. For instance in 1974 the USAF awarded McDonnell Douglas a two million dollar contract to support attempts to break the time-to-climb records previously held by the F-4 Phantom and the MiG-25 Foxbat. The aircraft used for this attempt was the F-15A (Serial No 72-0119) known as the "Streak Eagle". It was able to out climb the Apollo moon rocket to 60,000ft and its performance smashed all previous records and was highly publicised.

However, that aircraft was highly modified by removing all non-essential combat systems in order to save 1800lb in weight. Right down to a saving of 50lb of paint, which of course meant flying the Eagle naked, which is how it came by its name! The performance of the Streak Eagle is very well known, yet it can not be seriously compared with any production model F15.

The Jane's F15 flight model data has been obtained from the aircraft manufacturers and other official USAF sources, and as such, is as accurate as any non-classified data can be. It's quite simply as good as we can ever expect. But what do we expect? In simulations of modern air combat where at least some basic aircraft data is almost always highly classified, the wise flight sim' pilot won't expect the modelled aircraft to compare to the real thing with extreme fidelity.

As important as comparison with the real world may be, the competitive flight sim' pilot is more concerned with the performance of the aircraft as represented by its flight model. In any case, if the non-classified data is good, the aircraft will match some of the more public numbers and remain within the realms of credibility.

As an example consider the data available for the maximum speed of the F15. Published data that is readily available quotes the maximum speed of the F-15A as 1650mph at an altitude of 36,000ft, that's Mach 2.5 or two and a half times the speed of sound. At sea level the maximum speed is quoted as 915mph or Mach 1.2 which is comfortably supersonic and compares favourably with the sea level performance of Jane's F15.

Similar figures are also quoted for all later models of F15 regardless of the differences that exist between them and some of that data is listed in the following table for reference. While a top speed of Mach 2.5 remains the only publicly available data, there is little doubt that the performance of production F15's fall significantly below that figure. Indeed, the specification for Mach 2.5 was controversial right from the beginning because of the degrading effect that such a capability would have on the performance in the transonic region of the envelope, which is much more critical in combat.

While such considerations remain contentious, what really matters to most is how the in-sim' aircraft performance compares with that of their artificially intelligent or online opponents. They expect the physics of the flight modelling to be sophisticated enough that real world tactics can be successfully employed against their opponents.

They also hope that the relative performance of dissimilar aircraft is such that it will dictate similar tactics to those used in the real world. That generally means that energy and angles tactics when appropriately employed bring correspondingly predictable outcomes. This article will explain how modern methods of aircraft performance comparison can be applied to the F-15E as modelled in the Jane's simulation. In doing so I will frequently refer to the real F-15 by way of validation and in the course of that discussion you will learn how to get the most from your aircraft when competing against others.

In order to do that we will use a method of comparison that allows a pilot to visualise the contrast between the performance of different fighters and determine which one is superior to the other at each point in the envelope. So for example a pilot might compare the flying characteristics of an F-16 to those of a MiG-29 and thus identify what regions of the flight envelope are most advantageous or dangerous to him. The method was originated and developed in the early sixties and revolutionised the way the USAF looked at tactics and designed fighters.

It is particularly relevant in this case because it was used extensively to validate the design of the F-15. It was also largely responsible for the rejection of the early 60,000lb variable geometry aircraft proposed in the Air Force FX concept formulation package, in favour of the 30,000lb fixed wing, high performance fighter we know today. The method is based upon the theory of energy manoeuvrability and can be translated into simple graphs called EM Diagrams or Doghouse Plots. The advantage in using them is that they are very easy to read and permit aircraft comparison at a glance.

I will use Energy Manoeuverability theory to explain how you can fly the F-15E to its full potential, and squeeze every drop of performance from the flight model in order to win against less informed pilots, but first let's compare the Jane's F-15E to the real F-15A. That exercise will bring the comparison issue into perspective and provide us with a feel for the Strike Eagle's performance relative to a more familiar aircraft.

Download Dan Waldrep's latest F15 Mission: Bridge Busters ATC: 1 meg This mission includes a large number of custom voice files... = )

Go to Part 2.