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By Lieutenant Colonel Brendan M. Greeley, Jr., U.S. Marine Corps (Retired)
This is the first of a series of reports on the aircraft expected to compete for the U.S. Air Force-U.S. Navy Joint Primary Aircraft Training System (JPATS).
The Pampa 2000 trainer, powered by a high-bypass ratio turbofan engine, combines excellent handling characteristics with fuel economy and offers impressive performance for a primary trainer. Vought Aircraft Company has teamed with Argentina’s Fabrica Militar
de Aviones (FMA) to enter the aircraft in a winner-take-all competition to provide an estimated 765 primary training aircraft for the U.S. Air Force and Navy.
The Air Force wants to start replacing its T-37s late in the decade, and the Navy
will begin replacing its T-34Cs about 2002. The Air Force is the lead service for acquisition, and the JPATS office at Wright-Patterson Air Force Base, Ohio, in July issued a tentative operational requirements document. The formal request for proposals is scheduled to be released in the summer of 1993, but Congressional concerns for joint training not just joint aircraft—may delay this.
JPATS requirements include: familiarization (to include night landings), precision acrobatics, instruments, formation, plus high- and low-altitude navigation (day and night).
Each contender is required to present an aircraft, a ground-based training system, and logistic support. Vought and
FMA have teamed with Loral Defense Systems, Akron, Ohio, to provide the ground-based training systems and with UNC Aviation Services, Annapolis, Maryland, to provide contractor logistics support. [See “The JPATS Contenders,” Proceedings September 1992, pp. 90-91.] I flew the aircraft in late July from the Vought plant at Naval Air Station Dallas, Texas. I had flown it three years ago from the front cockpit and, this time, to get an instructor’s eye view, I took the
rear seat. James Read, Vought’s chief test pilot, strapped in up front after giving me a good cockpit check-out. The aircraft was technically an IA-63, but differences between it and the Pampa 2000 will be mainly in the form of cockpit layout and instruments. The Argentine Air Force currently uses the IA-63 as a trainer.
As with most modem trainers, the air-
VOUGHT
The IA-63 offers maintenance personnel easy access to equipment from ground level. The engine tail cone is attached to the engine (see break above tailpipe), and comes out still attached to the power plant (above). The Pampa offers exceptional visibility from the rear cockpit, which is protected by an internal windscreen.
craft has been designed to afford servicing and access to equipment from ground level. The aircraft is equipped with two sealed lead batteries and does not require any external equipment for starting.
Vought and FMA are betting that the Pampa s performance throughout a broad airspeed, altitude, and g-envelope will give them the edge, at least as far as the aircraft portion of the competition is concerned. Final approach speed in the Pampa is 110 knots, and the aircraft is capable of achieving more than 450 knots calibrated air speed at sea level. On this particular flight, I had the aircraft near both ends of the speed range, and pulled 4g’s on overhead maneuvers. We were limited by weather in the acrobatic operating area to about 17,000 feet, so I was unable to explore the Pampa’s performance at higher altitudes.
We planned to head out to the working area, evaluating aircraft handling on the way, do clean and dirty stalls, acrobatics and spins, and then return to the field for some touch-and-go landings— all in all, a fairly typical acrobatic-stage training sortie.
Tentative requirements specify that JPATS aircraft must be able to maintain a constant-altitude, constant airspeed, 60° angle-of-bank turn at 22,000 feet above mean sea level (MSL), which equates to a 2-g turn. The IA-63 had no difficulty with this maneuver at 16,000 feet at reduced power settings, even though we still had some fuel in the wing tanks and were maneuvering to bum down before doing some spins. Read told me that he and his team had flown the aircraft through all the required maneuvers without any difficulty.
The stepped-up rear cockpit affords excellent visibility for an instructor. The company has yet to decide on the ejection seat for the Pampa 2000; the aircraft I flew had a Stencel zero-zero ejection seat and strapping in was straightforward with standard shoulder and lap-belt fittings. You do have to attach the seat pan with two additional fittings and hook up leg restraints; Read said that they are considering a single-point release system to simplify things and make egress easier. Seat adjustment is standard, and the rudder pedals can be moved fore and aft with foot-actuated levers that would be familiar to many pilots.
He talked me through the cockpit from left console—oxygen, engine controls, rudder trim—to the instrument panel and down the right console—battery switches, radios, and lights. Although all switches were easy to see and reach, the team plans to standardize on a slightly different layout. The angle-of-attack indicator and the g-meter, for example, located at the top of the panel where they are easy to see, are currently vertical tape displays. The operational requirements document, however, currently specifies that the aircraft “must have an AOA [angle-of-attack] system with a circular gauge on the instrument panel and a standard yellow-red-green chevron-type indicator in head-up field-of-view. The circular gauge must present ‘on speed' at the three o’clock position and stall at the twelve o’clock position ... the gauge should have a maximum range and maximum endurance index.” Post-start checks are standard and included cycling the flaps and speed brakes and checking the trim actuators for proper movement. The trim-position indicators are located on the lower portion of the instrument panel. Monitoring them is relatively easy during the checks and in flight, but checking them—particularly the stabilator—during the takeoff roll requires that you glance down inside the cockpit. More than one student has inadvertently rolled in full nose-down trim on takeoff; putting this indicator in
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a more visible position might pay dividends later on.
The aircraft can carry 2,400 pounds of fuel internally, which gives it enough endurance to fly a two-hour training mission and still land with required reserves, Read said. On a typical training-mission profile the aircraft bums fuel at a rate of about 850 pounds per hour, he said. Air Training Command T-37s typically bum about 1,300 pounds per hour, according to the operational requirements document.
Bought
The Pampa’s fuel is carried in four separate tanks:
^ A 105-gallon flexible fuselage tank * A 153-gallon integral wing tank ^ Two 52-gallon outer wing tanks—one °n each side.
We lit off with a partial fuel load consisting of full fuselage and integral wing lank—a total of 1,700 pounds; the outer w'ng tanks were empty. Spins are prohibited with fuel in these tanks and we hid not need the fuel anyway. Read anticipates that most training flights will launch with the full internal fuel load— 2,400 pounds.
Read handled the radios and gave me Ihe aircraft to taxi. I found the nose-wheel steering well-calibrated. The rudder ped- a|s had a good solid feel as I made the turn out of the chocks and 1 was able to heep my heels on the deck and play the Pedals to counter any tendency to over- c°ntrol. We were the only aircraft taxing, but instructors coaching students through parking ramps stacked with train- ®rs and fuel trucks would find the excel- ent visibility from the rear cockpit very c°niforting, particularly at night.
With takeoff checks complete, I lined UP on the centerline, stood on the brakes, and went to full power. Runway temperature was 80° Fahrenheit and the wind was calm. All the gauges read normal; I released the brakes and we rolled. We were light and the aircraft accelerated rapidly.
The aircraft has a negative angle-of- attack on takeoff, Read had told me during the brief, and he recommended that I ease the stick back about one inch accelerating through 80 knots and hold it until rotating the aircraft at takeoff speed to make the transition less abrupt. I did this, but rotated a bit slowly going through 110 knots and we ate up a couple of hundred more feet of runway than we really needed. Even so, we were airborne in about 1,500 feet on Navy Dallas’ Runway 17—headed toward the lake and the well-known towers.
Gear and flap limits are 170 knots. I raised the gear at 130 knots with a positive rate of climb, and got the flaps up going through 150 knots; there was no tendency to settle as the flaps retracted. We leveled off at 2,500 feet to stay underneath the terminal control area (TCA). 1 held the 210 knots climb speed initially but then pushed it up to 250 knots at Read’s suggestion to expedite our transit to the working area. I was still well back on the power at 250 knots. At 30 miles, we were out from under the TCA and cleared to climb.
We were in a stable air mass and there was no turbulence, even at low altitude. The Texas thermals had given us a break.
At full power and 210 knots, the aircraft initially picked up a 4,500 foot rate- of-climb; going through 10,000 feet, we were climbing at 3,000 feet-per-minute (FPM). Read said that this would drop off to 2,000 FPM at 20,000 feet, and to
- FPM at 30,000 feet, Service ceiling for the aircraft is 42,000 feet.
We flew around cloud decks and rain showers on the climb; clear of the airways, we leveled off for some steep turns. The aircraft maintained level flight at
- feet in a 60° angle-of-bank, 2g- turn with plenty of power in hand. The stick forces were good.
The aircraft has excellent slow speed characteristics. I stalled the aircraft clean and in the landing configuration and the aircraft gave plenty of warning and recovered well. There is ample increasing buffet approaching the stall, and the aircraft stalls cleanly with no tendency to fall off on a wing. I did an approach-turn stall with the gear and flaps down with the same results—plenty of warning followed by a straight-forward recovery when I lowered the nose, leveled the wings, and added power.
There were no other aircraft in the area, but once again I was impressed by the excellent visibility from the rear cockpit as we checked the air space before starting a given maneuver. I did a series of aileron rolls and wingovers before setting up for some overheads.
The aircraft rolls at about 150° per second at 250 knots indicated air speed, and can attain roll rates of up to 190° per second at higher airspeeds, Read said, adding that he considers the stick forces a bit stiff at trim, although still light enough to do acrobatics. He was leaving for Argentina a few days after the flight to conduct tests on modified aircraft.
I set up for a loop at 300 knots indicated at 12,000 feet, added full power, and picked up 4gs on the accelerometer. I was lined up on a road, but I relied on the all-attitude indicator to keep the wings level in the scattered to broken cloud conditions. The angle-of-attack indicator, the all-attitude indicator, and the g-meter are all centrally grouped almost directly in the line of sight at the top of the instrument panel; students should find this helpful when starting to do acrobatics.
I was slow on the g-schedule, and we went over the top at about 140 knots. It was easy to shift my focus from the g- meter to the angle-of-attack indicator on top, but there was really no need to do so, since the aircraft has a good feel and we were never close to the buffet. As it was, I leveled off at 13,000 feet—the result of pulling too easily initially and pulling too hard on the recovery—combined with a rather rusty scan pattern. A definite “below average,” by any instructor’s standards. After a few more turns, we were ready to start spinning the
JPATS Update
The operational requirements document cites numerous performance, supply, and safety deficiencies that hamper training with the T-37B and the T-34C. Among them:
- The unpressurized T-37B accounts for 50% of all Air Force pressure-related physiological incidents, while accounting for only 7% of the flight hours.
- The T-34C has the highest number of g-induced loss of consciousness (GLOC) incidents of any Naval Air Training Command aircraft, because of the rapid g-onset rate and the lack of an anti-g restraining system. The T-37B’s GLOC rate is twice that of the T-38.
- The T-37B’s performance at altitude limits training effectiveness; the T-34C, designed to operate below 10,000 feet, is even more limited. Any new aircraft must be able to operate effectively throughout the high-altitude structure; this requires pressurization.
- The T-37B’s 17-knot crosswind limit restricts 8-10% of all scheduled sorties at the Air Force’s northern Texas and Oklahoma bases.
- Current T-34C gross weight and center-of-gravity concerns are critical.
- Both aircraft are becoming increasingly difficult to support.
The JPATS competition as structured will complete the Navy’s transition from a three-phase, three-aircraft (turbo
prop-jet-jet) jet training pipeline to a two-phase, two-aircraft program. The progression for many years has been from the T-34C to T-2C to TA-4J. Now the T-45A Goshawk is scheduled to replace the T-2C and the TA-4J while the JPATS winner will replace the T-34C. Multiengine pilots also will start in the JPATS aircraft.
The Air Force for many years has had a two-phase, two-aircraft pipeline for all its pilots: primary in the T-37 and advanced in the T-38 (although it recently instituted specialized training in the T-1A for tanker and transport pilots). For some years, the service has screened candidates in the Cessna T-41, a military version of Cessna’s piston-engine 172; earlier this year, the Air Force selected the team of Slingsby Aviation Limited (Great Britain) and Northrop to deliver a variant of the Slingsby Firefly to replace the T-41.
Complicating the JPATS program is pressure from Congress to consolidate flight training, hardly a new issue, but one that has surfaced again as the services continue to downsize. Critics continue to question the Navy’s decision to put helicopter pilots through fixed-wing training,, for example, and why at least some phases—perhaps primary—could not be combined.
B. M. Greeley, Jr.
aircraft and we climbed out heading for a clear area.
The Pampa has two spin modes, which Read had covered in detail in the brief. The first is really more like an oscillatory, post-stall gyration, entered by stalling the aircraft and feeding in full rudder deflection while holding full aft stick. The aircraft rolls in the direction of the rudder deflection, pitches nose down, and begins to rotate; aircraft attitude oscillates between about 60° nose down to level with the horizon. The motion is not particularly violent and the aircraft loses about 1,000 feet per turn. Neutralizing the controls will cause the aircraft to recover.
The only way to get into the second mode—a fully developed autorotative spin—Read said, is to cross the controls at spin entry by feeding in full aileron opposite to the rudder deflection as the aircraft departs. It takes two turns to stabilize in the spin, and the aircraft loses about 500 feet per turn. Recovery is effected by maintaining full aft stick while pushing opposite rudder and putting the aileron into the spin—the controls must then be neutralized as the aircraft stops its autorotation in order to avoid snapping into a spin in the opposite direction.
If the services are satisfied with the training provided by the rudder-only spin mode, the aircraft is ready to go, Read said. The Vought-FMA team is continuing to define the ideal control configuration for a fully developed, autorotative spin should that be required, Read said.
He showed me a rudder-only spin, and then I tried one; the aircraft performed as advertised, with the nose oscillating between the horizon and about 60° nose low, and recovered immediately when I neutralized the controls. The full autorotative spin also went as briefed. He did one and then I followed: I had neglected to adjust my rudder pedals, which were a bit long, and I had to stretch to hold full left rudder, full aft stick, and full right aileron, but when I did it right, the aircraft performed as advertised.
During the descent on the way back to NAS Dallas I cycled the speed brakes and there was no pitch change; I had been impressed with this characteristic on a previous formation flight.
We broke at 250 knots—speed brakes out, power back—and lowered the gear and flaps decelerating through 170 knots. I left the speed brakes out and picked up 120 knots off the 180° position at 1,000 feet above ground level (AGL) to begin the approach. Read recommended an approach speed of 110 knots and I had stabilized by the 90°. I was high, and the ball came off the top of the mirror. The aircraft responded well as I eased down to the glide slope and flew a reasonable approach until just before touchdown, when I eased the power back and flared. There was no tendency to float, and the aircraft touched down firmly—the aircraft was not designed for the stresses of a carrier landing. There is no requirement for the JPATS aircraft to land aboard ship.
I shot three landings and the aircraft handled well throughout the pattern; it has a solid feel. There was little wind, but the aircraft does have a crosswind capability of 25 knots. Instructors will find landing the aircraft from the rear cockpit easy, a real plus in the night touch-and- go pattern.
Back in the chocks, we shut down with 500 pounds of fuel; we had burned almost exactly 1,200 pounds on our 1.4- hour hop.
Lieutenant Colonel Greeley is an associate editor at Proceedings. He was designated a naval aviator in 1963, and flew A-4s throughout his career, which included two tours in Vietnam and duty as the operations officer of an advanced jet training squadron fly* ing the TA-4J. He commanded VMA-223, an A-4M squadron, prior to his retirement from the Marine Corps in 1982.