When Agility Matters, But You Don't Need It
For every student who doesn’t care much for geometry, there’s a fighter pilot who appreciates how important it is, especially in aerial combat. Angles and energy management determine speed and position when maneuvering for the kill shot. Those factors determine the difference between the quick and the dead once the fight is engaged.
Flying at high angles of attack, or AOA, – aka high alpha – fighter aircraft gain enhanced nose-pointing capability, allowing pilots to find, fix on, and target enemy aircraft. The ability to point the nose rapidly is how pilots outmaneuver the enemy, get lock on them with radar guided and heat seeking missiles and take the decisive shot.
AoA refers to the angle between an aircraft wing’s chord line, the imaginary straight line between the wing’s leading and trailing edges, and the aircraft’s flight path. It’s not to be confused with attitude, the jet’s relation to the earth. Attitude is seldom the same as AoA.
When the angle between the aircraft’s chord line and the flight path is small, the aircraft is at a low angle of attack. When larger, the aircraft is at a high AoA.
During flight test, F-35 high AoA testing pushed the jet to the AoA limit of fifty degrees nose high and beyond both positive and negative maximum command limits.
Tests were initially conducted in the stealthy, clean wing configuration. Later tests included flights with externally mounted pylons and air-to-air missiles and also with open weapons bay doors, which created additional drag on the aircraft. Test pilots took the aircraft beyond this limit to evaluate its characteristics in recovering from out-of-control flight conditions.
While AoA is critical for maneuvering, the days of actually closing with the target, rolling and turning to get behind your opponent, are waning. That’s why the F-22 Raptor and F-35 Lightning II are stealthy; to give US and allied pilots the first-shot/first-kill advantage and launching missiles from beyond visual range, without being detected.
Since the 1991 Persian Gulf War, there has been a steady increase in the number of air-to-air victories from beyond visual range, or BVR, have been reported. In fact, the last aerial gun kill was recorded in 1988.
With the F-35’s multi-source onboard sensor data coming into the cockpit and the 360-degree visibility provided by the Distributed Aperture System (DAS), it’s pretty tough to surprise an F-35 pilot in aerial engagement.
Military fifth generation tactics emphasize formations, multiplying the number of sensors looking for threats. The inputs gathered during these formations merge with information from off-board sensors on satellites and other Intelligence, Surveillance and Reconnaissance, or ISR, aircraft to build a comprehensive, fused picture of the battlespace.
The F-35 was also designed to make nine g turns with a full load of internal fuel and weapons, far outclassing any enemy jet with their externally-mounted missiles and fuel tanks. The F-35 is designed to complement current fourth generation tactical fighters, such as the F-16, F/A-18, and F-15 in terms of maneuverability. However, the design of the Lightning II is optimized for stealth to operate in contested airspace environments that would otherwise be off limits.
The Future Of Air Combat
"The F-35 is very capable in the within visual range, or WVR, environment, and its high AOA maneuverability is one of the tools available to maximize its lethality and survivability, according to Capt Joshua Reddis, an F-35A pilot assigned to the 58th Fighter Squadron at Eglin AFB, Florida.
“However, the F-35's greatest strength is its ability to acquire and fuse information permitting decision-making and lethal employment at range, prior to being detected by the adversary in question,” Reddis added.
“Whether you are talking about air-to-air or surface-to-air entities, the ability to avoid or destroy threats prior to them becoming a factor renders high g and high AOA maneuvering unnecessary, even if the airframe itself performs well in those envelopes,” Reddis explained.
“The bottom line is that the F-35 is designed to be highly survivable and extremely lethal in a high-threat, near-peer environment,” he continues. “Nevertheless, those same features are equally applicable to a low threat conflict where it can load additional external ordnance and bring its sophisticated information management capabilities to the current fight."
The F-35’s combination of stealth, electronic warfare, cyber capabilities, and almost as a last resort, agility, will seriously degrade each step in an enemy’s ability to detect, track, shoot at, and ultimately get close to threaten an F-35.
Written by Eric Schnaible, the F-35 Flight Test communicator at Lockheed Martin. This is his first article for Code One.