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The aerodynamically clean Grumman/Agusta S2I1A, powered by a Pratt & Whitney-Canada JT15D-5C turbofan, can perform acrobatics at altitudes above 20,000 feet and handles well in the landing pattern. It is a small, straightforward aircraft with predictable flight characteristics.
rpi . .
ls is the fourth in a series of reports °'1 'he aircraft expected to compete for e U-S. Air Force-U.S. Navy Joint Primary Training Aircraft System (JPATS).
I he Grumman/Agusta team is con- ■*- vinced that its turbofan-powered llA JPATS candidate will have the
j, e~cycle costs of any of e iet contenders—and at this combination will Carry the day.
Jhe last two trainer/ b^re®ner aircraft bought P^he Pentagon—the Air tr°rce’s tanker-transport aa‘mng system (TTTS) j ds enhanced flight )e teener—were both secCted 0n that basis, acq r ln8 to Phil Murphy, utnman’s S211A di- 0r of business devel-
W Firefly to screen Pro^Pective pilots, sior, rV®man and Agusta J^d their JPATS team. agreement in October the first of the
looi™“t0 do so- “We
at all trainers, and picked and its S211,”
a« m6 c*laracterized jets in SQ0re suitable trainers ti0n016 areas: “Consider a close forma- do itC[0ss'under in a big prop; you can that th Ut d Ptovitles negative learning in ifi6(j 5 technique would have to be mod- jets ]» W^en the student transitions to
Ple> ]Ur?^ ^escribed the S211 as a sim- craft !?dtWe‘ght, low-technical-risk air- ,at Was built from the ground up nrnary trainer. The aircraft’s max-
imum takeoff gross weight is 6,393 pounds, which includes the maximum internal fuel load of 1,500 pounds. Its Pratt & Whitney of Canada JT15D-5C twin- spool turbofan, which weighs 665 pounds and produces 3,190 pounds of thrust, is virtually identical to the -5B model that powers the Air Force’s T-1A Jayhawk tanker-transport trainer; the -5C’s oil sys- tern has been modified to permit inverted flight.
The S211, which first flew in 1981, has been in service as a trainer in Singapore since 1985 and in the Philippines since 1990, where it has demonstrated 3.1 maintenance-man-hours per flight-hour, Murphy said. He thinks this could decrease to 2.6 in U.S. service because the aircraft will not be required to do the weapons training it does in those countries. About 85 trainers have been built. If it wins the competition, Grumman may build the S211 in New York but the final decision has not been made, according to Murphy. In any case, the aircraft will have better than 78% U.S. content, he said.
I flew the S211A in May while it was on tour at Andrews Air Force Base, Maryland. It is a clean design and the workmanship is excellent. The super-critical wing seems to flow into the top of the air intakes. All primary structures are aluminum, but there are some composites in secondary structures. Offered a choice of seats, I took the rear cockpit to check out the instructor’s eye-view, and Grumman test pilot Dave Kratz, who flew F-14s while on active duty, strapped in up front. The aircraft sits low to the ground and has an extendable step that retracts into the fuselage.
The standard cockpit I saw has been replaced by an electronic flight instrument system in the team’s actual JPATS contender, which was shipped to the United States from Italy and assembled at Grumman’s Calverton, New York, facilities. Kratz and Agusta’s Gabriel Zanazzo took the aircraft up for its first flight on 1 June. The Grumman/Agusta team is planning to deliver a high-fidelity cockpit mock-up to the Air Force as part of its proposal and is keeping the configuration under wraps. The basic aircraft I flew did incorporate several JPATS-specific improvements, including the the new -5C engine, ventral fins, and single-point refueling.
Visibility from the stepped-up rear cockpit is excellent and all switches were easily accessible. The aircraft had a standard Martin-Baker Mk-IOL zero-zero ejection seat, but the JPATS contender will be equipped with a lighter Mk-16L seat, which Murphy said will cost less. There are a lot of straps to hook up, typical of many of the JPATS contenders; flight instructors will appreciate anything that can be done to simplify this—especially those strapping in for the third time on a hot day in Texas. Grumman and Agusta are planning on a singlepoint release system.
I started the aircraft on its own power. With the battery on, I hit the start switch, moved the throttle to idle passing 10%—and the engine lit off and stabilized at 52%. Post-start procedures were standard and, after checking the brakes, I turned out onto the broad Andrews ramp and found that the aircraft handled well with the mechanical nose-wheel steering. On the aircraft I flew it is always engaged; on the actual JPATS contender it will be selectable. I veered left and right several times in the process. “Just checking it
The S211A’s stepped-up rear cockpit provides excellent visibility and the aircraft has a tight turning circle when taxiing. Versions of the twin-spool turbofan engine are in service with the U.S. Air Force and commercial operators. Manufacturer’s specifications call for engine changes in less than two hours. Ventral fins are an addition to the S211A.
out,” I said. “That’s what they all say,” replied Kratz.
The aircraft’s flight-control system relies on push-rods and bellcranks, although the ailerons are hydraulically boosted with a manual backup; the 3,000 pound- per-square-inch hydraulic system powers the landing gear, speed brakes, aileron servos, and the compressor for the environmental control system. Murphy emphasized the value of cockpit cooling on the ground at idle power, and said that F-15 and F-16 pilots who had flown the aircraft said that the S21 lA’s system is as good as those in their tactical aircraft.
Our gross weight at takeoff was 6,100 pounds, which included 1,275 pounds of fuel, although the aircraft can carry up to 1,500 pounds of fuel internally in wing tank and a fuselage sump. We we1 cleared for position and hold on runwj 19-Right. With takeoff trim set and* indicator lights in the green, one-ha Haps, and controls free, I lined up on ft center-line, released the brakes at jammed the throttle from idle to 100°
acceleration time was well within the second limit.
We had a slight left cross-wind c0f ponent but the aircraft tracked well some use of nose-wheel steering duft the initial portion of the roll. The rud" became effective quickly and I di^ gaged the nose-wheel steering. Foil0' ing Kratz’s advice, I rotated to 10°1,0 up passing 100 knots, and we were11 borne in about 1,500 feet. The aircraft'1 celerated quickly and showed no t0 dency to settle as the flaps were retra^ The outside air temperature was ” Fahrenheit, almost a standard day, ceiling was 1,200 feet with tops at’0 2,500 feet and visibility was three I"1 in the Andrews area.
The regular S211A has a 160-kfl°JJ striction on the landing gear and a 1 ^ knot limit on full flaps, which will t>e, creased to 160 knots on the actual contender. Both handles are logically j sitioned and I had no trouble locating, flap handle without looking after get the gear up. J
We were headed for Restricted A 4006 off Patuxent River, but our if1
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il^are* 'urns. The aircraft rolled Per second, handled well, and
of 2t, set a' 85% and an entry speed float ,*cnots- 1 used three G’s and we
dicar °Ver the t0P at 26>000 feet in-
ljsjnln8 60 knots—a little bit slow. knot§ 'be speed on top was 80 lOo k ant* at we went over a' acrohn°tS ^le aircraft obviously has feet3tlC capabilities above 20,000
cat0re ®'meter and angle-of-attack indi- Upp are conveniently located at the e't of the instrument panel and
Span Length Height Wing Area
27 feet, 6 inches 31 feet, 2 inches 13 feet, 5 inches 132.25 square feet
Empty weight Max T.O. weight
4,460 pounds 6,393 pounds
Internal fuel capacity
(Max Cross WT, SL.
Dive speed 400 KIAS (0.8 Mach)
Rate-of-climb 5,100 feet/minute
Stall speed (full flaps)
Endurance (10% reserve)
3 hours, 25
Sustained load factor
clearance turned us east toward the Chesapeake Bay and kept us at 2,000 feet—right in the heart of the layer—until were clear of traffic descending into Washington National. I trimmed up the aircraft and held 240 knots indicated— ^ell back on the power—on a heading of uy0°. My scan pattern was simplified considerably by the Presence of a large attitude gyro in the renter of the panel— hke the AN/AJB-3A familiar to so many readers. As noted, me panel I saw will e considerably dif- terent in its elec- honic reincarnation m the JPATS S211.
Cleared to climb, added 100% and *Je aircraft was jmmbing at 4,500
ten Per-minute PM) as we went through 5,000 feet sc^edule at tt knots indicated lr speed until pick- Jtg up Mach .45.
'he rate-of-climb ,!?PPed to about 3,800 FPM passing H o Pect and to 3,000 FPM passing still ^ feet. At 20,000 feet we were 2c''mbing at slightly more than t’ 0 PPM. We had been handed off j atuxent River during the climb and oj-^veled off at 22,000 feet for a series the 1118 anc^ vv'ngovers; the weather in area was clear and we could see CQe a'r station across the bay. JPATS taintenders must be capable of sus- at ?u,n® a 2"S turn (60° angle-of-bank) PfoblS a^*tude, ar|d the S211 had no em maintaining the turn with the P°^r set at only 85%.
Q,rePt fbe power there while I went Win a series of aileron rolls and s 8°vers and then added power for s°me hi ■ F
at 160° 1
• ntr°l forces were light. I went right a series of overheads with the
will probably remain there in the final cockpit configuration, Kratz said. JPATS requirements stipulate a circular angle- of-attack gauge with the on-speed indication at the three o’clock position and the stall at the 12 o’clock position. Despite the move to glass cockpits and digital displays, some analog instruments still provide the most easily assimilable information.
When I stalled the aircraft clean at
22,000 feet, there was plenty of buffet warning and the stall came at 100 knots with no tendency for a wing to drop. 1 adjusted the nose, added power, and the aircraft climbed out of the stall. With gear and flaps extended, the aircraft stalled wings-level at 85 knots and recovered smoothly. I rolled into a 30° bank, still with the gear and flaps extended, for an approach-turn stall and the aircraft once again recovered with little loss of altitude. The aircraft’s stall characteristics are predictable and certainly suitable for a primary trainer.
We followed these maneuvers with several spins. The S211 has an oscillatory and a steady-state spin mode, and the steady-state mode is a bit difficult to induce at this stage
The S211A has a side-hinged canopy and belly-mounted speedbrakes (above). The actual JPATS contender (I-JPAT), assembled by Grumman on Long Island, made its first U.S. flight on 1 June from the company’s Calverton, New York, facility.
go of the stick. The aircraft departed, pitched nose-down, and began flying again. Recovery was straightforward. The engine never hiccuped during any of the maneuvers. “You can’t surge the engine,” Kratz said. We headed for NAS Patuxent River to shoot some touch and goes. Four spins was enough for my out-ofpractice semicircular canals.
On the way we picked, up 340 knots and the aircraft handled well when trimmed. Control forces were light but not overly sensitive. We made a sweeping turn to the south to line up for the initial at Patuxent River and came into the
break at 250 knots. Kratz’s decision to use Patuxent River was a good one— there was only one other plane in the pattern and there were no traffic problems. Runway 06 was the duty and the 150710 knot surface winds gave us a direct 90° right crosswind.
1 broke at mid-field, popped the speed brakes,
pulled the power to idle, and dropped the gear as we decelerated through 160 knots. I rolled out too wide abeam, dropped full flaps at 140 knots, brought the speed brakes in and stabilized at 110 knots. I was back around 80% during the descent through the 90° position but the engine accelerated well. Throttle position and power settings corresponded and I had no trouble making adjustments. I ended up with a long, angling final, and when I rolled out on runway heading I used wing-down and top-rudder to counteract the crosswind. I flared crossing the numbers and touched down at about 95 knots. I added power, left the gear and flaps down, and turned downwind for some more touch-and-goes.
The aircraft handled well throughout the pattern and the crosswind had little effect; visibility was excellent from the rear cockpit. I shot a no-flap approach with a pattern speed of 130 knots and the results were the same, although I was farther back on the power. I asked Kratz 1 extending the belly-mounted speed brake would allow higher power settings on af proach, but he said that they added littk drag and tended to scrape on the arresl ing-gear cables.
The aircaft can accept a 13 feet-pd second sink rate at touchdown, whic! might make it possible to fly constat angle-of-attack approaches to touchdo"' under some conditions—obviously a pk for getting Navy and Marine Corps stt dent pilots ready for their first cad11 landings in the T-45.
I cleaned up the aircraft after the 1,1 flap landing and headed for Andre'' where the weather had improved and1 runway had changed. We were cle^1 for a straight-in to runway 01 -Left, wl"‘ had a slight right crosswind. I go*J
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the brakes right after touchdown, aircraft decelerated rapidly with no I£, dency to swerve, and we cleared a1 first exit and taxied in. We shut do'1 with 375 pounds of fuel remaining! had burned 900 pounds on a 1.3-h1' flight that closely resembled a typ|1 training command sortie.
of development, Kratz said. I entered the first one at about 19,000 feet, clean, and at idle power. At the stall, I put in full back stick and full left rudder, and held them. The aircraft pitched over and entered the spin oscillating between 20° and 70° nose down. We did four full turns and I recovered by easing the stick forward and stepping on the right rudder; the aircraft stopped spinning immediately and stabilized in a steep nose-down attitude. I popped the speed brakes, and recovered using optimum angle-of-attack. We bottomed out at about 15.500 during the recovery, having lost about 700 feet pier turn, but with full power we were quickly back up to 17,000 feet.
[II] did the next spin to the right, but this time I just let go of the controls after four turns and the aircraft recovered by itself. Back at 19,000 feet, Kratz took the controls and attempted to induce a steady-state spin by feeding in rudder at a slower rate as the aircraft stalled but the aircraft promptly went into its oscillatory mode. We tried again with the same results. Grumman and Agusta are still working on this aspect, although Kratz said that the services may consider the dominant oscillatory mode satisfactory for training.
At Kratz’s suggestion, I then took the aircraft 90° nose up, simulating an unusual attitude, hit zero airspeed, and let
Colonel Greeley is an associate editor at' ceedings. He flew A-4s throughout his which included service in Vietnam and . as operations officer of an advanced jet ing squadron flying TA-4Js. He comma11f VMA-223, an A-4M squadron, prior to h1’ tirement in 1982.