Aviation Week & Space Technology, Jun. 6, 2011, p. 39


Web headline: Inflight Evaluation Of Embraer's Super Tucano

Flying the EMB-314

Super Tucano proves to be a strong LAS contender, but is that enough to win contract?

By Fred George Sao Jose dos Campos, Brazil

Sierra Nevada Corp. and Brazilian manufacturer Embraer are fielding the EMB-314 Super Tucano, a veteran counter-insurgency aircraft, as one of two finalists in the U.S. Air Force's upcoming Light Air Support program. Hawker Beechcraft's AT-6 is the other contender in the hotly contested procurement. USAF should announce the winner in June or July.

Initial stakes in the Light Air Support (LAS) competition are modest: 20 aircraft for delivery to the Afghan air force starting in 2013. Another 15 will be procured for use by USAF as trainers to assist partner nations to strengthen their own air forces. But the program has the potential to grow to 55 aircraft and $950 million if USAF exercises all options under the indefinite-delivery/indefinite-quantity contract.

The Super Tucano, also known as the A-29, has been in service with the Brazilian air force as a trainer and a light attack aircraft since 2003 and has been ordered by Chile, Colombia, the Dominican Republic, Ecuador, Indonesia and two undisclosed nations. The aircraft has flown more than 16,000 hr. in combat, mostly with the Colombian air force, including many night missions.

The Super Tucano also was evaluated by the U.S. Navy in 2008 as a potential close-air support aircraft under the classified Imminent Fury program, but a planned lease of four aircraft for operational deployment never went ahead. The AT-6 and EMB-314 went head-to-head in a fly-off for the LAS program in January at Kirtland AFB and Truth or Consequences, both in New Mexico. The results have not been made public.

Aviation Week flew the Super Tucano in April. Embraer demonstration pilot William Souza first walked me around the aircraft, where I was able to compare it to the AT-6 I flew last year. The Super Tucano has a larger footprint—it is 4 ft. longer, with a 3-ft. greater wingspan and a 2-ft., 4-in. higher tail. Empty weight is 26% greater and maximum takeoff weight is 1,900 lb. heavier. The main gear has a 50% wider track, plus its tires are larger and are inflated to a lower pressure, potentially providing better unimproved landing-strip capabilities than the AT-6. The Super Tucano also has anti-skid power brakes, an advantage when operating on short, contaminated or improved runways.

Both aircraft are powered by 1,600-shp Pratt & Whitney Canada PT6A-68-series turboprops with 4,500 hr. time between overhauls (TBO). The Super Tucano's -68C can maintain that power up to ISA+16.2C and the AT-6's -68D should have a similar flat rating, so neither aircraft would seem to be a stand-out hot-and-high performer in Afghanistan.

Souza pointed out the aircraft's 4-lb.-bird-resistant windshield, single-point pressure refueling system, 15 in. of propeller ground clearance and the jump-start capability that allows one Super Tucano to supply electrical power to another with a dead battery by means of onboard extension cords. The aircraft has two internally mounted, 250-round, 0.50-cal. FN Herstal machine guns in the wing, along with five NATO-standard external stores stations—two on each wing and one under the center fuselage. Those stations can carry up to 3,420 lb. of external stores with fully loaded guns.

The Super Tucano's inboard-wing and center-fuselage stations also can carry, respectively, 547-lb.- and 507-lb.-capacity external fuel tanks in place of munitions. Each external tank extends endurance by about 1.1 hr. The five stations can carry Mk-81, Mk-82 and Mk-117 bombs, which weigh 250, 550 and 750 lb., respectively. Stores include laser-guided bombs, 2.75-in. rockets and air-to-air missiles.

By comparison, the AT-6 can carry 3,280 lb. on six NATO-standard wing stations. But two of those stations may be occupied by 400-round, 0.50-cal. FN Herstal HMP-400LC machine-gun pods because it has no internal guns. Fully loaded two-gun pods weigh about 600 lb., so the four other wing stations can carry up to 2,680 lb.

Both aircraft can be equipped with chaff and flare dispensers and electro-optic/infrared (EO/IR) sensors. The Super Tucano's dispensers are mounted in the left- and right-wing root fairings, while the FLIR Systems Brite Star II EO/IR sensor ball is mounted under the forward fuselage. Notably, the EMB-314's sensor turret is mounted ahead of the wing leading edge, and has a less restricted field of view than the under-wing EO/IR ball on the AT-6.

Embraer and the Brazilian air force have qualified 133 different external stores configurations for the Super Tucano. However, we flew the aircraft without external stores on our demo flight.

Strapping into the front seat, I noted both the EMB-314 and AT-6 have similar cockpit layouts, with full-function head-up displays, dual Martin-Baker zero-zero ejection seats and hands-on throttle-and-stick controls. The Brazilian air force aircraft we flew was equipped with two multifunction displays and a head-up display in the front cockpit. Newer versions have three Elbit color multifunction displays in each instrument panel.

Compared with the AT-6, the Super Tucano has a larger bubble canopy providing better visibility. It also has external front and internal rear windshields, so the aircraft remains controllable if the canopy is lost in flight.

Switching on electrical power, we used the up-front control panel to program the aircraft's runway performance computer. The system has weight and drag look-up tables for all 133 external-stores configurations. Runway performance computations can be based upon using the full 1,600 shp of takeoff power or, when feasible, the 1,250 shp alternative power rating. This can reduce engine wear and maintenance costs.

Our zero-fuel weight was 7,224 lb. with two pilots and empty guns. With 1,091 lb. of fuel, the ramp weight was 8,315 lb. before engine start. Using Sao Jose dos Campos' 2,120-ft. field elevation, a barometer setting of 1014 hPa (29.94 in. Hg), an outside air temperature of 24C, and compensating for the internal wing guns, the computer predicted a 1,778-ft. runway roll and a 3,504-ft. takeoff distance based on a weight of 8,271 lb., using full takeoff power and flaps extended. Computed rotation speed was 89 kt. indicated airspeed (KIAS) and best angle-of-climb speed was 116 KIAS.

We closed the canopy, started the engine on external power and switched on the oxygen-generating system and avionics. The aircraft uses engine bleed air, processed through an air-cycle machine pack, for air conditioning. Despite the PT6A-68C's modest bleed output, the air-cycle machine quickly cooled the cockpit.

The aircraft also has an air-intake inertial separator that can be deployed to minimize the foreign-object damage risk on unimproved runway surfaces. We did not need to use it on the pavement here.

I switched on the automatic rudder-trim unit that compensates for P-factor (asymmetric thrust from the large propeller), checked the manually actuated primary flight controls, verified the laser inertial-reference/GPS-navigation system was ready, pulled the safety pins out of the ejection seats and started to taxi to Runway 15.

Rolling out of the chocks, I found the power brakes to be a little sensitive, but very positive in action. Up to 20 deg. of nose-wheel steering is available via the rudder pedals. Differential braking can be used for tight turns on congested ramps.

Once cleared for takeoff, I pushed the power control lever to the forward stop and the engine stabilized at 88% torque, equivalent to 1,408 shp. Acceleration was brisk and little rudder was needed to maintain heading.

Retracting the gear and flaps, I noted little pitch moment with configuration change. We accelerated to 145 KIAS and climbed to 15,000 ft. en route to the northeast operating area, dodging several cumulonimbus build-ups. Once level, the aircraft cruised at 285-300 kt. true airspeed (KTAS) at full power in turbulent air. This added credibility to Embraer's claim of a 320-kt. KTAS maximum cruise speed at lower altitudes.

We then descended to 10,000 ft. for a series of aerobatic maneuvers, including loops, barrel rolls and wingovers. The aircraft exhibited excellent control harmony and little rudder was needed to maintain balanced flight because of the automatic rudder trim unit.

We also fully stalled the aircraft in clean and dirty configuration. The stalls were preceded by plenty of aerodynamic buffet. Pitch force increased quite linearly as angle of attack increased. In both stalls, the nose pitched down gently. The dual ventral strakes under the tail enhance directional and pitch stability, so there was no tendency for wing drop during the stall. Relaxing stick back-pressure and adding power resulted in nearly immediate stall recovery. I have not flown a military aircraft with better stall characteristics.

Spin behavior was equally benign. In both fully developed left and right spins, we initiated recovery by centering the stick and countering with opposite rudder. The nose dropped almost straight down within one turn and we recovered by pulling out of the dive. We used a hands-off recovery technique during the third spin—once pro-spin control inputs were relaxed, the nose dropped within one and one-half turns and we pulled out of the dive.

Souza then demonstrated the aircraft's ability to couple the autopilot to follow a multi-leg flight plan at low altitude. This reduces pilot workload, providing more time to set up for weapons delivery. Then he demonstrated the head-up display's continuously computed impact point, continuously computed release point and dive-toss attack modes. The dual Elbit mission computers use radio altitude to estimate target elevation. Brazilian air force Super Tucanos are fitted with an indigenous data link, but the avionics system has an open architecture with generic 1553B and Arinc 429 data buses that can accommodate U.S. Link 16 communications equipment, including the situational awareness data link and enhanced position location reporting system radios.

Security firm Blackwater (now Xe) integrated Link 16 and other U.S. intelligence, surveillance and reconnaissance equipment onboard a company-owned Super Tucano for the U.S. Navy's Imminent Fury program. Sierra Nevada, as prime contractor for Embraer's LAS bid, has extensive experience in fitting such equipment to various platforms and would integrate the Super Tucano into the Link 16 net-centric environment if needed to support the LAS program.

After multiple runs on simulated targets, we returned to Sao Jose dos Campos to enter the overhead left break for airfield pattern work. The aircraft proved easy to handle. We flew the pattern at 140 KIAS and typical final approach speeds were 108-109 KIAS. We also flew a couple of simulated engine-out practice landings using a 130 KIAS glide speed and no flaps.

The Super Tucano proved to be a strong contender in the LAS program competition, but USAF will consider many factors besides the raw merits of each aircraft. Sierra Nevada and Embraer point out that more than 150 Super Tucanos are in service with seven countries and the fleet has amassed more than 100,000 flight hours, one-sixth of which have been in combat operations. The fleet has a 99.2% dispatch rate and an 86% full mission-capable availability, they assert. Based on fleet statistics, Embraer claims that less than one maintenance manhour is needed to support each flight hour.

If they win the contract, Sierra Nevada and Embraer plan to assemble the aircraft in Jacksonville, Fla. About 40% of the aircraft's value comes from components made in the U.S. and Canada and more than half of the Brazilian manufacturer's stock is owned by U.S. citizens, company officials say.

In comparison, Hawker Beechcraft's T-6 Texan II trainer, the aircraft upon which the AT-6 is based, has logged more than 1.5 million flight hours. More than 680 T-6s have been delivered since it entered service in 2000; the majority are operated by the U.S. Air Force and Navy.

Hawker Beechcraft officials argue that the U.S. military has acquired a wealth of T-6 operating experience in the last decade, and its support logistics are well established. The AT-6 shares 85% of its components with the trainer. Also, the Wichita, Kan.-based company employs 1,400 people involved with the T-6 program, says Chairman/CEO Bill Boisture. If the AT-6 wins the LAS competition, he asserts, it would provide a new export product to help improve the U.S. balance of trade.

Such arguments resonate with many U.S. politicians. But the AT-6 has yet to be tested in combat, even though its capabilities promise to closely match those of the Super Tucano. The A-29, in contrast, has distinguished itself in combat in Colombia, and this has spurred the interest of other nations seeking a proven counter-insurgency aircraft.

In spite of its merits, the Super Tucano faces an uphill battle in the LAS competition. The U.S. military has billions invested in its T-6 Texan II trainer and likely will want to leverage that investment in a new LAS aircraft. The Brazilian entry would be brand-new to the U.S. military and it would take time to ramp up training, logistics and operational experience.

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