Enduring value

The Astra has been a steady, if not stellar, seller since IAI introduced the aircraft in 1985 as a long-range, high-speed, mid-size business jet. The design mated a stretched Westwind II fuselage with a new, low-set, swept wing featuring a cranked leading edge and supercritical aerofoil section. This increased both speed and range compared with the straight-wing Westwind.

In 1990, IAI introduced the Astra SP with a new interior, upgraded avionics and aerodynamic refinements to improve performance. The airframe and engines were unchanged, however, the SP retaining the Astra's two 3,700lb thrust (16.5kN) AlliedSignal TFE731-3A turbofans. Flight International evaluated the original Astra in 1985 and the SP in 1992.

Since then, IAI has created the Astra SPX, which was certificated by the US Federal Aviation Administration in 1996. To exploit further the potential of the Astra wing, the SPX has been endowed with more power by fitting new TFE731-40R turbofans rated at 4,200lb thrust. This results in a maximum range of 4,470km (2,950nm), maximum altitude of 45,000ft (13,725m) and a typical cruise speed of 470kt (870km/h) (true airspeed) or Mach 0.82 which, IAI claims, makes the SPX the performance leader in its price segment among six/nine-seat business jets.

MARKETING STRENGTH

IAI, meanwhile, has strengthened its marketing and support capabilities by becoming a partner with the Pritzker group in Galaxy Aerospace, the UScompany formed in 1997 to "-produce, market and support a line of advanced technology business aircraft". The product line includes the Astra SPX and the new Galaxy "super mid-size" business jet, which is now undergoing certification flight testing at IAI's Tel Aviv facility.

According to president Brian Barents, "-our principal objective with Galaxy Aerospace is to build an organisation that will compete aggressively with other major business jet producers. With two-thirds of the business jet market in the USA, we need to have a strong US presence and we are doing that by basing our headquarters, completion centre, product support and factory service centre in the USA".

The company's $12 million headquarters is to open in Fort Worth, Texas, late this year. Unpainted and unfurnished Astra SPX and Galaxy aircraft will be flown from Tel Aviv to the new facility for the installation of interiors and optional avionics and final painting.

The Astra SPX is now well established in service, with more than 20 already delivered to customers. The presence of an SPX demonstrator at the Farnborough air show, however, provided Flight International with the chance to flight test the latest version of this business jet.

Parked on the ramp, the Astra displays its origins in the dated profile of the fuselage, which lacks the svelte attractiveness of newer designs. The cockpit windows are heavily framed and the eyebrow windows, although functional, are unfashionable. The build quality of the aircraft seemed excellent, and the paint finish was outstanding. As with most business jets today, attention has been paid to the positioning and accessibility of systems and service points to facilitate quick turnrounds.

Airframe ice protection is provided by pneumatic boot de-icers on the wing and tailplane leading edges. The boots are well finished and snug fitting, but again look anachronistic. Most modern business jets employ bleed-air anti-icing systems. IAI justifies the use of a pneumatic de-icing system because of its minimal effect on engine performance, low maintenance costs and light weight.

The elliptical cross-section of the cabin provides good head and shoulder room for seated passengers and the ceiling height over the central aisle is 1.7m. A separate airline-style lavatory is at the rear of the cabin and includes a novel overhead window. There is a wide choice of cabin furnishings available to customers and a galley is included.

There is no access from the cabin to the 55ft3 (1.56m3) aft fuselage baggage compartment, which has a large external door. A 380 litre (1,00USgal) removable fuel tank can be installed in the baggage compartment, reducing its capacity from 500kg (1,100lb) to 170kg. The operator, therefore, has the choice of longer range with the tank and less space for cargo, or shorter range and maximum space without it.

The US-registered (N297GA) Astra SPX demonstrator did not have the baggage compartment tank installed. The 2,320kg fuel load was contained in the two integral wing tanks and one centre fuselage tank. The aircraft did not have an auxiliary power unit (APU), but about 80% of SPXs have been ordered with the optional AlliedSignal GTCP 36-150W APU.

Company training captain and demonstration pilot Jim Lewis took the right hand seat for our flight. The cockpit is a blend of the new and the not so new. The four 185mm-square Rockwell Collins Pro Line 4 displays dominate the instrument panel, but are complemented by analogue dials. The engine instruments have recently been updated, with a small, neat group of analogue/digital dials replacing the two columns of four instruments for each engine.

Entering and leaving the cockpit requires a stretch over the centre console. The seats are adjustable fore and aft, for height and recline, and the foldaway armrests are adjustable for height. The rudder pedals can be adjusted for reach via a crank handle on the lower portion of the instrument panel between the pilot's knees. The field of view is good, except for the rather thick windscreen pillars, and is much enhanced by the eyebrow windows, particularly when manoeuvring at high angles of bank. Each pilot can easily see the wing tip on his side. There are roll-across black perforated sunblinds for the eyebrow and side windows.

The AlliedSignal TFE731s have digital electronic engine control (DEEC) units. In the absence of an APU, the engines were started using the aircraft batteries. Once the first engine had been started, a pause was required to allow the rate of charge to the battery from the engine-driven generator to reduce to 115A before the second engine was started. The DEEC would have initiated automatic shutdown if a start cycle had malfunctioned.

The nosewheel steering tiller (on the captain's side only) came readily to hand and was pleasant to use. The nosewheel steering was nicely geared and the wheel brakes were progressive and smooth.

TAKE-OFF

For the take-off from Farnborough's runway 25, the weather was pleasant and the surface wind light. The Astra SPXwing has both trailing-edge flaps and leading-edge slats. The flaps can be set at 12°, 20° or 40°, each setting being accompanied by deployment of the slats. For our take-off, 20° of flap was used - the setting which, I was told, gives best second-segment climb performance.

The all-up weight was 8,870kg, compared with a maximum of 11,250kg. The centre of gravity was just aft of mid position. At rotation speed, a large control stick movement was required to rotate and unstick the Astra. The initial rate of climb after undercarriage and flaps were retracted was 5,000ft/min (25.4m/s).

During acceleration to the 250kt climb speed, the nose-up pitch change had to be countered with a long application of nose-down trim via the control yoke switches. The variable incidence tailplane is used for pitch trim, and is moved by an electrically powered actuator. It seemed that the normal pitch trim was low-geared. The elevators are manually operated. If an elevator were to jam, an emergency pitch trim could be selected for longitudinal control up to and including the landing.

Much of the climb to altitude was through cloud under radar control, which precluded manoeuvring. It was a good opportunity, however, to evaluate the Collins electronic flight instrument system (EFIS). Each pilot has a primary flight display (PFD) and a multifunction display (MFD) with the usual facility to switch formats between screens if desired.

The PFD has a normal format including an attitude and direction indicator with a vee-bar, and a vertical ribbon airspeed presentation with an overlay for reference speeds and a speed trend cue. The altimeter presentation is also a vertical scale, with overlays for radio altitude, minimum descent altitude and preselected altitude. Each pilot's MFD has a menu including compass rose, map mode and weather radar. A traffic alert and collision avoidance system is an optional extra.

CREW ALERT PANEL

There are no aircraft systems synoptic pages. At the centre of the instrument panel, beneath the engine instruments, there is a crew alert panel with amber and red legends, or "attention getters". The DEEC takes care of the engines once the power levers are placed in the climb detent. The fuel feed and balance between the three tanks is maintained automatically.

Once we had broken through the deep cloud cover, above 25,000ft, conditions were ideal. The SPX has pleasantly harmonised primary flying controls. While the rudder and elevators are manually activated via push rods, the ailerons are hydraulically boosted.

The result is an aircraft which is pleasant to fly and fairly easy to trim - once one has become accustomed to locating the aileron and rudder trim controls, housed in a well on top of the centre console.

During the climb at 250kt, at 30,000ft, a rudder pedal "doublet" was applied in an attempt to provoke Dutch roll. With the yaw damper in the result was dead beat; with the yaw damper out, three cycles ensued before the couple was damped. The Astra was pleasant to fly in steep turns and a roll from 45° of bank to 45° of opposite bank at M0.77 showed good roll acceleration and an impressive rate of roll.

In a block of airspace from 38,000ft to 42,000ft, a steep turn at M0.74 did not cause stall buffet. Acceleration to M0.81, wings level, and an estimated +1.5g pull did not provoke Mach buffet. The airbrakes consist of four hydraulically operated spoiler panels on the upper surface of the wing, two on each side. They can be either in or out, with no intermediate setting. Selecting the airbrakes out at M0.74 resulted in a slight nose-up pitch and a slight aerodynamic burble. With the power levers at flight idle and airbrakes out, the rate of descent at M0.71 was 7,000ft/min.

A valley in the cloud tops presented a suitable place to try two stalls although, to maintain a safe margin above the broken cloud, these had to be done at 22,000ft. The Astra has no artificial stall warning, nor a stick pusher, and relies on good natural stall characteristics. The all up weight was by now 8,180kg.

In the clean stall, the buffet onset was at 124kt and the lowest speed recorded was 113kt in heavy buffet. With the undercarriage down, slats extended and flaps at 40í, the buffet onset was at 103kt and the lowest speed 97kt. In both cases, roll control was good into the stall, while heavy buffet and a gentle nose drop defined the stall rather than a noticeable G-break.

Little useful work could be done in the traffic pattern, or with an actual or simulated engine shut down, because of Farnborough's heavy traffic load, the low cloud base and thick cloud cover. During the recovery to Farnborough, the flaps and undercarriage were selected at just below their limiting speeds, resulting in only slight and easily trimmed pitch changes. The limiting speeds are 250kt for slats and 12° flaps, 225kt for 20° and 180kt for 40° flaps - and 250kt for the undercarriage.

EASY APPROACH

The visual approach was cosy and pleasant to fly and only a token flare was required to arrest the final descent and plant the wheels on the runway. The undercarriage was, perhaps, slightly less compliant than I had expected. The combined effect of the Dee Howard thrust reversers, ground spoilers and powerful wheel brakes brought the aircraft smoothly and effortlessly to taxiing speed.

The current "book price" for a standard Astra SPX, without an APU, is $11.7 million and it appears to offer good value at that price, but the design has probably now reached the economical limit of its development potential.

The wing continues to demonstrate the soundness of its concept, however, as the same basic design is now used for the Galaxy business jet. This "widebodied" aircraft has an expected maximum operating Mach number of 0.85. The scheduled US certification date for the Galaxy is December 1998, and a flight test of that aircraft will make for an interesting comparison with its older, smaller stablemate.

Source: Flight International