AFTI/F-16 DFCS and IF/FCS Program

F-16 Advanced Fighter Technology Integration
In March 1980, General Dynamics began converting the sixth FSD F-16A to serve as the technology demonstrator aircraft for the joint Flight Dynamics Laboratory-NASA Advanced Fighter Technology Integration (AFTI) program. The AFTI F-16 built upon GD’s experience with its YF-16 CCV program, and the AFTI F-16 even received the twin pivoting vertical ventral fins from the CCV aircraft, which were likewise installed under the air intake. The aircraft was also fitted with a narrow dorsal fairing along its spine to house additional electronics. Technologies introduced and tested on the AFTI F-16 include a full-authority triplex Digital Flight Control System (DFCS), a six-degree-of-freedom Automated Maneuvering Attack System (AMAS), a 256-word-capacity Voice-Controlled Interactive Device (VCID) to control the avionics suite, and a helmet-mounted target designation sight that permitted the forward-looking infrared (FLIR) device and the radar to be automatically “slaved” to the pilot’s head movement. First flight of the AFTI F-16 occurred on 10 July 1982. The Air Force Association gave its 1987 Theodore von Karman Award for the most outstanding achievement in science and engineering to the AFTI F-16 team.^[45][46]
The AFTI F-16 participated in numerous research and development programs:^[47]

• AFTI Phase I testing (1981–1983): a two-year effort focused on proving the DFCS system.
• AFTI Phase II testing (1983–1987): evaluation of the wing-root-mounted FLIR and the AMAS system.
• CAS/BAI (1988–1992): a five-phase evaluation program testing a variety of low-level close air support/battlefield air interdiction (CAS/BAI) techniques, including an Automatic Target Handoff System (ATHS) (which transferred target data from ground stations or other aircraft to the AFTI F-16) and off-axis weapons launch.
• Talon Sword Bravo (1993–1994): demonstration of cooperative engagement techniques where the aircraft fires at a target based on targeting information datalinked from a distant sensor; the weapon principally investigated was the AGM-88 High-speed Anti-Radiation Missile (HARM).
• EGI (1994 & 1997): testing of embedded GPS/INS (EGI) navigation systems, including evaluation of the reliability of GPS in jamming environments.
• AGCAS (1994–1996): testing of an Automatic Ground Collision Avoidance System (AGCAS or Auto-GCAS) to help reduce the incidence of “controlled flight into terrain" (CFIT); lessons learned from this program were further evolved on the F-16 GCAS.
• J/IST (1997–2000): testing of the world’s first all-electric flight control system under the Joint Strike Fighter Integrated Subsystem Technologies (J/IST) program.

Mr. John H. Watson was the General Dynamics Program Manager for the AFTI/F-16 DFCS Program and led the pre-proposal development effort, the proposal presentation and the performance of the program objectives through the Digital Fly-by-Wire Flight Control System development and initial flights. Mr. Watson was instrumental in building the engineering team to accomplish this task. The AFTI F-16  contract  was managed by the USAF Flight Dynamics Laboratory at Wright-Patterson AFB, OH. The conduct of this program enabled General Dynamics to built one of the finest (Digital) Flight Control System houses in the world and lead to providing digital flight control systems for the F-16C/D/E/F, the F-111, the F-22, the F-35/A/B/C, the South Korean T-50,  and the Republic of China (Taiwan) IDF aircraft. . The use of these digital systems also enabled significant other development efforts using the AFTI/F-16 aircraft before it was retired.

The YF-16 CCV Program

F-16 CCV Program

F-16 CCV

The first YF-16 (#72-1567) was rebuilt in December 1975 to become the USAF Flight Dynamics Laboratory's Fighter CCV Program. CCV aircraft can have independent or "decoupled" flight control surfaces, which make it possible to manoeuver in one plane without movement in another -- for example, turning without having to bank. The CCV YF-16 was fitted with twin vertical canards added underneath the air intake, and flight controls were modified to permit use of wing trailing edge flaperons acting in combination with the all moving stabilizers. The fuel system was adapted, so that by transferring fuel from one tank to another, the position of the aircraft center of gravity could be adjusted. The YF-16/CCV flew for the first time on March 16, 1976. On June 24, 1976, it was seriously damaged in a crash landing. While still more than half a mile out, the engine suffered from a loss of power and in the resulting crash landing the landing gear collapsed. Repairs took over 6 months, and its flight test program was resumed in the spring of 1977. The last flight of the YF-16/CCV was on June 31st, 1977, after 87 sorties and 125 air hours had been logged. A few years later, the AFTI/F-16 Program would capitalize on the experience gained from this CCV program. The pre-proposal development effort and the actual proposal presentation were both lead by John H. Watson and Leonard H. Schrieber of General Dynamics. The Principle Engineer for General Dynamics was Dr. Jack D. McAllister and the USAF Flight Dynamics Laboratory's Program Manager was Mr. Robert P. Johannes.

AIR COMBAT FIGHTER COMPETITION

Air Combat Fighter Competition
Increased interest would turn the LWF into a serious acquisition program. North Atlantic Treaty Organization (NATO) allies Belgium, Denmark, the Netherlands, and Norway were seeking to replace their F-104G fighter-bombers.  In early 1974, they reached an agreement with the U.S. that if the USAF ordered the LWF winner, they would consider ordering it as well. The USAF also needed to replace its F-105 and F-4 fighter-bombers. The U.S. Congress sought greater commonality in fighter procurements by the Air Force and Navy, and in August 1974 redirected Navy funds to a new Navy Air Combat Fighter (NACF) program that would be a navalized fighter-bomber variant of the LWF. The four NATO allies had formed the "Multinational Fighter Program Group" (MFPG) and pressed for a U.S. decision by December 1974; thus the USAF accelerated testing.

YF-16 on display at the Virginia Air and Space Center

To reflect this more serious intent to procure a new fighter-bomber design, the LWF program was rolled into a new Air Combat Fighter (ACF) competition in an announcement by U.S. Secretary of Defense James R. Schlesinger in April 1974. Schlesinger also made it clear that any ACF order would be for aircraft in addition to the F-15, which extinguished opposition to the LWF.  ACF also raised the stakes for GD and Northrop because it brought in competitors intent on securing what was touted at the time as "the arms deal of the century". These were Dassault-Breguet's proposed Mirage F1M-53, the SEPECAT Jaguar, and the proposed Saab 37E "Eurofighter". Northrop offered the P-530 Cobra, which was similar to the YF-17. The Jaguar and Cobra were dropped by the MFPG early on, leaving two European and the two U.S. candidates. On 11 September 1974, the U.S. Air Force confirmed plans to place an order for the winning ACF design to equip five tactical fighter wings. Though computer modeling predicted a close contest, the YF-16 proved significantly quicker going from one maneuver to the next, and was the unanimous choice of those pilots that flew both aircraft. On 13 January 1975, Secretary of the Air Force John L. McLucas announced the YF-16 as the winner of the ACF competition.
The chief reasons given by the Secretary were the YF-16's lower operating costs, greater range, and maneuver performance that was "significantly better" than that of the YF-17, especially at supersonic speeds. Another advantage of the YF-16 – unlike the YF-17 – was its use of the Pratt & Whitney F100 turbofan engine, the same powerplant used by the F-15; such commonality would lower the cost of engines for both programs. Secretary McLucas announced that the USAF planned to order at least 650, possibly up to 1,400 production F-16s. In the Navy Air Combat Fighter (NACF) competition, on 2 May 1975 the Navy selected a new proposed design by the joint team of McDonnell Douglas and Northrop based on a Navalized version of  the YF-17, that would become the McDonnell Douglas F/A-18 Hornet.

A Brief History of the 44th Bomb Group

A Brief History of the 44^th Bomb Group

B-24 Liberators were late comers to the 8^th Air Force. The B-17 Flying Fortress had been in combat since August 17, 1942 when 12 B-17E's were dispatched to Rouen, France. Having been activated January 15, 1941 at McDill Field, Tampa, Florida, the 44^th Bomb Group was the first really true Liberator group. It was assigned to a training operation to teach and form other B-24 groups. One of the groups formed after training with the 44^th was the 93^rd Bomb Group stationed at Hardwick, later known as the "Traveling Circus." The honor of being the first B-24 group to fly combat with the 8^th Air Force was the 92^nd on the 14^th raid by the 8^th Air Force, October 9, 1942. The 93^rd went to Lille, France with the loss of one plane. This was a rough mission against determined Luftwaffe opposition, whereas the first few B-17 missions were "milk runs." The 44^th Bomb Group was relieved of training duty and after a period of Anti-submarine patrol (sank one German U-boat July 10, 1942), arrived in England in October 1942 to join the 93^rd as the only two B-24 outfits in operations from the United Kingdom until September 7, 1943 when the 389^th Bomb Group flew with the 44^th to Bergen, Norway. Soon afterwards on September 9^th, the 392^nd Bomb Group flew its first mission to Albeville, France along with the 44^th.

The reason for the slow build-up of Liberator groups was that many that were originally destined for the E.T.O. were diverted to the Pacific Theater and for antisubmarine use.

Therefore, for all practical purposes, the B-17's were the primary aircraft of the 8^th Air Force for the first year. Never forgetting that the Liberators were dispatched to North Africa where in August they flew the most famous mission of World War II against Polesti.

The B-24 was the most sought after heavy bomber of the period due to the fact it could fly faster with a heavier bomb load for a greater distance than the B-17. Over 18,000 B-24's were built between 1939 and 1945. But the B-24 never had the charisma of the B-17's sleek appearance. With its two large vertical stabilizers and a squarish body, our B-17 friends referred to us in some uncomplimentary ways, i.e., "Flying Box Car," "Banana Boat," and "Pregnant Cow" for starters among other snide remarks. We B-24 flyers retorted by referring to the B-17 as "Hand Grenade Carrier," "Medium Bomber" etc. To this day, 40 years later, B-17 and B-24 veterans carry on this friendly rivalry.

Another problem was that B-17's and B-24's could not fly formation together due to the difference in performance of the two type aircraft. The B-24 had a long narrow Davis wing, perhaps the only graceful thing about the Liberator. This allowed the B-24 to fly 20 miles per hour faster than the B-17 but resulted in a more difficult plane to fly in formation as the prop wash of the lead planes tended to make the B-24 unstable. This required more effort on its pilots to keep a tight formation. Yet in all the hours I flew as navigator, I never heard any complaint from our pilot, Charles Peritti nor co-pilot, Burr Palmer. Neither did we ever seem to have trouble keeping a good formation.

The 44^th Bomb Group arrived in England October 1942 for a short stay at Cheddington Air Field before going to its permanent home base at Shipdham. The 44^th was known as the "Flying Eightballs." We were the only group in the Air Force with its own logo painted on the nose of every aircraft. The logo was literally an eight ball with wings and eyes and a long nose painted a different color for each squadron. Every 44^th'er wore this insignia with great pride on his flight jacket. The name was well earned, from the very beginning of combat, the 44^th had severe losses whereas the 93^rd had the lowest loss rate of the 8^th Air Force bomber command. Yet the 93^rd got a lot of attention in "Yank" and "Stars and Stripes" news articles. They dubbed them as the "Famous Traveling Circus" after a trip to Africa whereas the Eightballs were flying much rougher missions. There was no love lost between the 44^th and the 93^rd Bomb Groups.

The Fortress men called the 44^th "The Jinxed Outfit." The only time the 93^rd Bomb Group suffered worse than the 44^th was the August 1, 1943 bombing of Ploesti when the 93^rd, due to navigational error, came over the oil fields in the wrong direction thus sustaining nine planes shot down over the target area and two others that collided while returning to base. The Ploesti raid was the most famous, most recorded and written about in the history of the Army Air Force. The 44^th was lead by Colonel Leon W. Johnson, later Brigadier General in command of the 14^th Bomb Wing of the 2^nd Air Division to which the 44^th was attached while I was in combat. General Johnson and four other men were awarded the Congressional Meal of Honor for their heroic deeds in that famous mission.

My wife Doris and I were given the privilege of actually seeing the Medal when the 44^th had its reunion in Dayton, Ohio in 1984. Of all the men who flew combat with the Army Air Force in World War II, none command the respect and admiration as the survivors of the Ploesti raid.

Later that month of August 1943, the three raids in support of Allied troops in Sicily, the 44^th again had a disastrous loss of 8 planes versus only one for the other two groups. It was on the bombing of Foggia August 16^th that Suzy Q, the last of the original 67^th Squadron's planes and the one in which Colonel Johnson won the Medal of Honor, was lost. The "Eightballs" had suffered severely in Africa yet there was a fierce pride in the 44^th.

The 44^th, 93^rd, and 389^th Bomb Groups were returned to the 8^th Air Force in England in September 1943. From May through August, no B-24's were on combat missions with the 8^th Bomber Command. At this time, the 392^nd Bomb Group joined them to make four Liberator groups in the 2^nd Bomb Wing which was renamed the 2^nd Bomb Division and assigned a new plane insignia marking of a white circle on the stabilizers and wings with a large identifying letter. The 44^th's letter was "A", the 93^rd was "B", the 389^th was "C" and the 392^nd was "D" etc.

When I joined the group in April 1944, we still had mostly the olive painted planes with the circle "A." It was in April 1944 that the first natural metal B-24 H's and J's arrived and in late April 1944 the circle A was changed to a single black vertical stripe on the new all aluminum planes with squadron codes (the 68^th Squadron being W O) painted on the sides in very large letters.

Of course on D-Day June 6, all our planes were painted with bizarre black bands to identify us from any Nazi intruders flying in captured planes.

Our assembly ship was an old war weary B-24 D, an original aircraft that came to England with the 44^th even though she was late getting off and a survivor of the Polesti raid. She was known as "Lemon Drop." It had been stripped of all armament and repainted with alternate bands of black and bright yellow. When it was not my time to lead, we often referred to this assembly ship as the "striped Ass Zebra." I was a number of times assigned to be the assembly navigator in the Lemon Drop. The assembly ship was necessary to prevent pilots from assembling in the wrong formation. We would take off before the combat planes and reach the designated assembly area. The crew chief would fire off many flares to attract our group. When all the planes had gathered, I would lead them in the right direction and place at an exact time. The group proceeded on the mission, we returned to base.

On one occasion, I became so angry at the pilot on one of these assembly missions that I told the CO that I would never again fly with this particular pilot even if I were court-martialed. What brought me to this state of mind was an event that happened after the assembly had been accomplished. The pilot asked me where the field was, I told him it was directly below us. At this, the reckless pilot put the Lemon Drop into a steep spiral, just short of a spin. I looked at the air speed indicator, it was beyond the red line. Where the bomb sight had been removed, an aluminum plate had been installed, it was buckling. I had survived a number of missions but I thought my end would come in this foolish manner. I screamed at the pilot to pull the plane out of this dangerous dive. I was so mad, I was foaming at the mouth and only God knows what names I called the idiot.

Again in September 1943, the 44^th, 93^rd, and 389^th were dispatched to Africa after a few missions with the 8^th Air Force. Again the 44^th Eightballs took a beating with 8 planes lost on one mission along with another 8 crash landing, so badly damaged they could not return to England with the group a few days later. The 44^th was so disseminated, it could not take part in the first few missions after returning to Shipdham. But times would get better for the 44^th as the Liberator groups would have their number doubled by years end.

The last disaster of the Eightballs was April 8, 1944 when 11 out of 27 planes went down. This is when my crew was shipped from the 445^th Bomb Group as replacements. The jinx had been broken; never again would the 44^th suffer so disproportionately. We became one of the most respected outfits in the 8^th Air Force under the commands of colonel John H. Gibson until August 1944 and Colonel Eugene H. Snavely until V-E Day.

In the first part of 1944, the 8^th Air Force was divided into three divisions. The 2^nd Division consisted of 5 Combat Wings, the 2^nd, 14^th, 20^th, 95^th and 96^th. All were made up of 3 groups each except the 95^th with only two. The 14^th Combat Wing was composed of the 44^th Bomb Group, 392^nd Bomb Group and the 492^nd Bomb Group (June, July and August 1944 only when it was disbanded due to extra ordinary combat losses). The 492^nd Bomb Group was replaced by the 491^st Bomb Group when it was transferred from the 95^th Combat Wing to the airfield at North Pickenham to join the 14^th Combat Wing. The 95^th Combat Wing ceased to exist when the 489^th Bomb Group joined the 20^th Combat Wing.

More on the sad fate of the 492^nd Bomb Group later but needless to say, word wend around that the 14^th Combat Wing was jinxed even if the brunt of excessive losses transferred from the Eightballs to the 492^nd.

One could get the impression by reading the record of the 8^th Air Force that only the flying officers and men were responsible for the tremendous damage done to Hitler's Europe. Nothing could be further from the truth. Without the ground support personnel, not one bomber would have ever flown. I read with great interest Will Lundy's description of the April 14, 1945 "Salute to the Ground Man Weeks" event where 600 ground men gathered at the main ramp to be lauded by General Leon Johnson and Colonel Snavely. General Johnson, standing on the spot where he himself had received the Congressional Medal of Honor, stressed that for every aircraft in the air, 90 ground men each did his thing to make it possible. I wish I had been there to add my praise and shake as many hands as possible, especially the crew chief of Lili Marlene whose last name was Hill. I will never cease to admire their devotion to keeping our aircraft in flying condition no matter how damaged and shot up that we brought it back.

I noticed there was no effort for the ground crews to get close to us. Anyone could tell there was mutual admiration between us but I suspect we flying men lived in our own dream world and that the ground crews had seen too many of their "friends" not return.

For a more complete history of the 44^th Bomb Group, refer to The Mighty Eight: A History of the U.S. Eighth Air Force by Roger A. Freeman, pages 33 to 39. Also, Log of the Liberators by Steve Birdsall, chapter one and pages 67 to 76. But best of all, History of the 67^th Bomb Squadron by Will Lundy, the entire book. One might even view the excellent movie prepared by Captain David Klaus, the present 44^th historian.

After I completed my combat tour and was reassigned to the ZOI (Zone of the Interior), the 44^th Bomb Group remained in combat until VE Day. The group was inactivated July 12, 1946. Five years later in 1951, the group became the 44^th Strategic Bomb Wing flying B-29's and B-47's at Lake Charles, Louisiana. And finally in 1963, made into the 44^th Strategic Missile Wing at Ellsworth Air Force Base, South Dakota, where it stands guard to protect our peace to this very day and minute. We 44^th'ers are proud of our history both in time of war and peace.

There were seven Commanding Officers during the World War II period of the 44^th. Of these, I served under two, Colonel John H. Gibson (3/29/44 to 8/15/44) and Colonel Eugene H. Snavely (8/15/44 to 4/13/45). My 31 combat missions were from April through October 1944 with the 68^th Squadron, one of four, the others being the 66^th, 67^th and 506^th.

The 44^th Bomb Group was the first 8th Air Force group, B-17's or B-24's, to be awarded the Distinguished Unit Citation (DUC) for its May 14, 1943 raid on Kiel, Germany. A second DUC came with the famous Ploesti raid of August 1, 1943. The 44^th Bomb Group also served in the 8^th Air Force longer than any other B-24 group and sustained the highest MIA of any B-24 group with the most enemy fighters to its credit of any B-24 group, almost 400 damaged or destroyed.

The 44^th flew its last combat mission on April 25, 1945 making a grand total of 343. The average mission consisted of approximately 24 planes adding to a total of 9057 sorties of which 8009 were credited as combat flights. The total bomb tonnage dropped on the enemy equaled 18,980 tons during its two and one half years in the ETO and Africa.

My perspective on the fiscal cliff

VIEWPOINT: The fiscal cliff from a small town boy's perspective
Like many of you I learned the importance of financial responsibility at an early age. You simply don’t spend money you don’t have. The money you do have, you work for. And if you’re lucky, you might save some of that money for a rainy day or leave it for your kids once you’re gone.

Justification for FBW on the LWF

 

Andrew,

I thought your paper was excellent! I would like to know more of your work in the future since I am now retired, but still very interested in aircraft design programs.

Not that it really matters. but to set the record straight, from my standpoint, the following comments are offered for your consideration.

Reform-minded Deputy Secretary of Defense David Packard was very receptive when told that General Dynamics’ LWF proposal would incorporate Fly-By-Wire Flight Controls during a 1971 meeting with Harry Hillaker, Bob Widmer, etal. This was before Bob Widmer made the decision to incorporate Relaxed Static Stability. As a matter of fact, that possibility had not even been considered by him at the time. At the time at least, to my knowledge, no trade studies had been made to justify going to fly-by-wire flight controls. And then, actually, there were no longer any reason to perform such a study since the decision had been made, and in concrete, since it had been revealed to Secretary Packard. However, I believe that such a study, if conducted by an impartial group would find plenty of reasons to proceed to FBW. Control cables, tension regulators, dual input actuators, control stick assembly, etc will weight considerably more than the electrical implementation of the flight control system. The mechanical system will require more routine maintenance and repair costs. The mechanical system will require considerably more volume within the fuselage, empennage, and wings. Again, to my knowledge, no serious trade study was ever made between mechanical and electrical implementation for the LWF, YF-16, or F-16. Some have claimed that there were studies. I would like to see the results of such a study.

Again, I believe that your paper was very good and to a great extent hit the major points in a relatively short write-up.

Good luck to you.

John Watson, PE

Additional Comments about the LWF Flight Control Design

Additional Comments about the LWF Flight Control Design.

 

Automatic turn coordination was provided by an aileron-rudder interconnect, such that rudder pedal inputs are not normally needed. The rudder pedals are needed for taxiing and can be used to insert slight yaw angle inputs for gun pointing, etc. Some former F-4 pilots used rudder pedal inputs to facilitate rapid rolls during the early flight program of the YF-16. Since rudder pedal inputs were not needed for rolling the YF-16, rudder pedal inputs were limited in-flight. The differential horizontal tails supplemented roll control, especially at high-q flight conditions resulting in exceptional roll rate performance with the pilot’s feet of the floor.

Angle-of-attack (AOA) limiting prevents an our-of-control occurrence while maintaining normal airspeeds. Implementation of the YF-16 AOA-limiter design was conducted by George Sanctuary. Especially with the use of a heads-up-display (HUD), the pilot can fly with his head essentially “Out-of-the-Cockpit”, without fear of exceeding a critical AOA resulting in loss of control. This requires due diligence in acquiring good stability and control characteristics to very high angles of attack and sideslip.

More than 45 F-4 fighter aircraft were loss through loss of control (LOC) as a result of exceeding 20 units of angle-of-attack. For the F-4 fighter, it was the pilot’s responsibility to not exceed 20 units of AOA. However, the YF-16 AOA -limiter could only be defeated by allowing the airspeed to drop below normal flying speeds. The AOA-limiter was set to prevent the aircraft from going above a safe condition. For this reason, it was important to achieve very good quality wind tunnel test data throughout the complete angle-of-attack/sideslip range. Noticeable differences were observed in test results between various wind tunnels. Wind tunnel test results were further verified by flight test. Stability derivatives were adjusted for the affects of structural loads and structural dynamics.

Band-pass requirements for sensors and actuators were designed to be high enough but not too high, in order to minimize complexity of the structural filter design.

Special attention was given during the LWF pre-design stage to minimize the onset of buffet. Use of previous transonic wind tunnel based research on wing design including effects of leading edge and trailing edge flaps very helpful. This resulted in an almost buffet-free aircraft, even at the highest useable angles of attack.

The flight control system provides compensation for the six-barrel M-61 cannon fire reaction.  Some considered the use of twin single-barrel 20mm cannons. Structural bending modes for various fuel and weapons load conditions were considered in the location of rate gyros and accelerators. Electrically controlled speed brakes were incorporated on either side of the vertical tail just inside the horizontal tail plane. The horizontal tails were designed with a slight anhedral to effectively lower the tails with respect to the wing-chord plane. Careful attention was given to the pitching moment curves for full horizontal tail deflection range to fully understand the controllability of the aircraft. The leading edge flap angles in conjunction with well-designed ailerons were established to provide excellent roll control to high angles of attack.

 

The quadruple fly-by-wire system required extensive analysis and component failure mode studies as part of the redundancy management system design. The design objective was to provide two-fail-operate capability.

The LWF pre-design effort pointed the way for the 22-month detail design and build of the first aircraft, followed shortly by the second aircraft.

 

Control Configured Vehicle (CCV) studies included Relaxed Static Stability (RSS) were being sponsored by various government agencies, especially the Flight Dynamics Laboratory at Wright-Patterson AFB, Ohio. They had an ADP under the leadership of Mr. Robert (Bob) Johannes.

We were heavily involved in all the various concepts of CCV studies; however, the RSS was one that offered an exciting revolutionary improvement to aircraft performance. We had performed dynamic stability augmentation for all our aircraft designs going back to the B58, which had an automatic three-axis stability augmentation system. This system provided pitch, roll, and yaw damping, and automatic turn coordination. Also, it employed pitch and roll ratio changers because of the large range of weight and center-of-gravity, multiple configurations, and flight conditions. The rudder was also used to stiffen the aircraft at high supersonic flight conditions by feeding a lateral acceleration signal programmed by Mach number and altitude. This later feature was actually augmenting the static directional stability of the B-58. The aircraft also had an automatic pitch trim device. The F-111 aircraft had further developments that increased our confidence in pursuing the relaxed longitudinal static stability for the light-weight-fighter (LWF) program. Most of, if not all of the interest rested at the grass roots level of our organization with many more sceptics than supporters.

 

We began to establish design requirements. Control (Power) was considered as an important requirement. Of course, control of the static instability could not be left up to the pilot. The requirement was thus, “the pilot does not see this instability”. Recovery from upsets such as gust strikes and rapid maneuvers, etc were seen as important considerations. The usual requirements for sizing the horizontal stabilizers were still in effect. Pitch control power for nose-wheel unstick, rotation, landing flare, as well as full maneuvering capability were still required. Some people worried that limit cycle oscillations would be a problem. My primary S&C lead was opposed to RSS in the beginning along with a lot of company and government management.

This was obviously a very risky concept. It offered high payoff in performance, drag reduction, increased maneuverability, etc. but what if the augmentation system failed?  The aircraft would quickly depart from controlled flight and probably prevent the pilot from escaping.

Our existing design at the time included fly-by-wire flight controls. There was considerable opposition to that within the organization, but it would be required if the decision were made to go with RSS.

The decision to incorporate RSS into the design came quite suddenly when at the right time and place it offered a solution to a concern by top engineering management. The man that made the decision was known for his intelligent high-risk decisions that had paid off in almost all of our major programs.

The RISK was many risks. It may not have worked or we may not have been able to make it work. Hardware failures would be disastrous.  The Air Force customer may have figured it was too dangerous and politically risky to award us the contract.  Mr. Robert ”Bob” H. Widmer was a brave soul. He made the decision and then a good number of people set out to get it done and did it.