|MiG Alley Design Notes
by Rod Hyde and Andy McRae
MiG Alley is based on the Korean War: 1950-53. It was the first conflict that saw major jet v jet dogfights. The conflict also saw some jet v prop encounters. Among the many aircraft included, the game concentrates on the following:
The player will be able to pilot all the above aircraft except the B29.
The campaign, which forms the heart of the sim, consists of three parts:
In the Introduction, the player moves from squadron to squadron learning how to use the various aircraft in combat situations. This section of the game covers the period from the initial invasion to the Spring Offensive of 1951.
On moving to a new squadron, the player is presented with a series of missions to complete. These missions have been chosen to illustrate the action during the period. The missions will involve various aircraft from many different squadrons. Once a player has completed a mission, he will be able to replay it several times by flying other aircraft from other squadrons in the scenario.
MiG Alley will have over 3 hours of archive footage from the Library of Congress to introduce the Conflict to the player.
Spring 51 Offensive
This is the period when either side could have won the war. The frontline moved regularly as both sides attacked and defended aggressively.
The player is given charge of 5 squadrons with sixteen aircraft per squadron. There will be one squadron of each of the following aircraft types:
Although all squadrons will not be available on any one day, the player will still have a substantial force at his disposal. With this force, the player provides the air support to the ground forces and so he will be able to plan a range of missions:
The aim is to force the communists back towards the Chinese border and the position of the frontline will reflect the player's performance. The ground war will be modelled using data from actual battles that occurred during the Korean Conflict. The Communist supply network will also be modelled as accurately as possible.
On the ground the player will determine his priorities based upon:
The player will be able to plan missions in detail or he can just define the targets and let the computer do the rest. It is possible to plan a number of missions per day. However each aircraft can only be used once per day and the player can only fly one mission at a time. However if he arranges things so that some missions start after other missions have finished it will be possible to fly more than once a day.
At the end of the Spring Offensive, the player's achievements will be assessed. This will determine whether or not he starts the peace talks in a strong or weak position. The player will not actually be a member of the Peace Talk delegation. However, occasionally he will be asked to plan and instigate special missions to force the communistsí hand. These special missions include hitting dams. This will give us the chance of showing an animated "hill" of water rolling down a valley.
The player will receive radio chatter in voice and text. He will also be able to send messages. When on Close Air Support missions he will communicate with Forward Air Controllers and Ground Based Air Controllers.
The landscape is based on data from a variety of sources:
The Korean pennisula is more than 30 times bigger than the area covered in Flying Corps. Although, we want to have as much detail as in Flying Corps there will have to be some compromises. This area isn't fully sorted out yet. However we will probably reduce the data quality in some areas so that we can have better data on the frontline. This is important because we want to simulate a full ground war. As far as possible we will be basing the conflict on battles that actually happened.
Korea is mountainous. In comparison, northern France is as flat as a pancake. We should have plenty of opportunity to fly missions down the valleys in mountainous regions and go on bombing runs similar to the one in the climax of the Toko-Ri Bridges film.
In Mig Alley you will be able to fly the following aircraft:
The aircraft in Mig Alley are capable of realistically simulating many characteristics such as flic rolls, spins, aileron reversal, adverse yaw, slipstreaming, stalling etc. Many aerodynamic and inertial effects such as aeroelasticity, wing sweepback, dynamic coupling, compressibility are modelled. Real life aerodynamic data has been used to correctly couple all six degrees of freedom. In each case the characteristics of the aircraft have been carefully adjusted to reproduce real life performance.
With respect to the Mig Alley software the job of the flight model is to receive player inputs, then output aircraft position, velocity, feedback and instrumentation data. The model is executed every 30 milliseconds, independently of the display frame rate. Within each execution the following processes occur:
On the ground, undercarriage tire and leg suspension forces are modelled to make the aircraft's attitude, speed and position respond realistically to terrain geometry, engine thrust, player brake, steering and control surface inputs. You will observe the aircraft in Mig Alley tilting in response to acceleration, braking, turning and even wind gusts. In Mig Alley, if you taxi too fast and turn hard you will find you lose control as the aircraft skids.
Propulsion has two modes of operation. You can control the engines throttle setting, as a real pilot does. Or, you may simply control the engines thrust output. For prop aircraft, blade element theory is used to determine thrust/braking and reaction torque produced by the propeller. Engine reaction torque is passed to the airframe.
Atmospheric conditions vary from day to day in Mig Alley. Obviously pressure and temperature change with height. Wind and gusts are modelled three dimensionally. All these effects are included in the aerodynamics and propulsion calculations. Try landing a shot up Sabre on a dodgy airfield in a heavy, gusty crosswind without skidding down the runway sideways.
In three further articles I plan to discuss, in detail, the aerodynamics, propulsion, undercarriage, mass/inertia and atmospheric aspects and effects of the Mig Alley flight model and the aircraft modelled.
One of the major development objectives of the flight model was to achieve a high degree of accuracy in the performances of the Mig 15 and Sabre aircraft. A key feature of this objective was to ensure that the relative performances were true to life. Reports produced by pilots actually involved in the conflict and flight test / wind tunnel reports released by NACA (National Advisory Committee for Aeronautics) have been analysed and incorporated into the model. The data obtained, from our sources, has enabled us to achieve a superior level of accuracy. Some of the conclusions related to the relative performance of the Mig 15 and Sabre:
Other flyable aircraft (at present) are the Thunderjet (F84E), Shooting Star (F80C) and the Mustang (F51D). Note, three Sabre's are modelled (F86A, E, F) and two Mig 15's (original and the bis). The model can accurately simulate these aircraft as well, but, compared to the Sabre and Mig, less effort has been made in fine tuning all the hundreds of parameters.
The model has been designed and developed to reproduce key, combat, performance characteristics for each aircraft. These fall into two major categories, manoeuvrability and agility. Manoeuvrability (or energy manoeuvrability) basically is the aircraft's ability to change the orientation of its velocity vector and its energy state, that is, to turn, accelerate or climb. Agility, however, can be defined as the ability of the aircraft to change its orientation, that is, roll and pitch performance (mostly roll and pitch acceleration). Key aspects of the aircraft's combat performance that have been reproduced in the models, are:
The Mig 15 was light, powerful and beautiful. When flown by an aggressive and skilled pilot it was a formidable enemy, even for the Sabre. When you fly MiG Alley you'll find out how the '15 fares against the Sabre.
Weight and Inertial Moments
The magnitude and distribution of a fighter's weight has an enormous impact on the aircraft's overall performance, both in manoeuvrability and agility. Obviously the lighter an aircraft is, the better its performance will be. Aircraft with high moments of inertia about the longitudinal axis will generally have poorer roll acceleration. Likewise for pitch and the lateral axis. Wing tanks and stores will reduce agility and manoeuvrability, particularly roll acceleration.
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Last Updated January, 1998