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Dream Aircraft Page 13
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Page 13
An aerobatic fanatic has a choice of two 260-hp engines: the carbureted Lycoming, which is limited to 10 seconds of inverted flight, or the fuel-injected, Lycoming AEIO-540. This option includes inverted wing tanks and a Christen inverted oil system that allow the SF.260D to be flown upside down until either the fuel or the pilot is exhausted, whichever occurs first.
(The ultimate option is the SF.260TP, a turboprop version of the SF.260D. The TP, which has been in military service for years, was recently certified by the FAA as a civilian aircraft and is powered by an Allison 250B-17C, 420-shp engine that is derated to 350 shp. The TP has a 3,600-fpm climb rate and a maximum speed of more than 250 KTAS at 10,000 feet.)
The SIAI Marchetti SF.260D obviously is not for everyone. It is a machine for the discriminating pilot in search of style, performance and panache, something guaranteed to make his adrenaline flow. It is also one of the most seductive lightplanes ever developed.
In 1970, I was invited by the Federation Aeronautique Internationale to attend its annual conference in New Delhi. I was to have been honored there for having broken a world speed record in 1969 for piston-powered airplanes weighing less than 2,205 pounds (1,000 kg) at takeoff.
Flying an unmodified SIAI Marchetti SF.260, I averaged 199.48 KTAS around a 100-km, closed-circuit course.
Although grateful for the invitation, such attention was misdirected. This is because my speed mark was not attributable to superior airmanship. Any competent pilot could have done the same. Instead, the new record was a triumph of design, and the person who deserved the accolades was the SF.260’s designer, Stelio Frati.
Frati has always had a passion for performance and surgically removes drag from a design as if it were a cancer. Sleek lines and darting silhouettes are his trademark. In his own words, “I cannot understand how one can design an ugly airplane [when] it costs no more to build a beautiful one.”
Although the Italian designer had produced many noteworthy designs, he did not develop a low-wing monoplane until 1951, when he created the F.4 Rondone (Swift), a 90-hp, two-place aircraft clocked at 147 knots.
His first commercially successful design was the F.8L Falco (Hawk), which had a maximum speed of 184 knots using only 160 hp. It currently is available only in kit form.
Frati’s first all-metal design was to become his most famous. In the early 1960s, he designed the SF.250 (the SF represents the designer’s initials), a three-seat sporting machine that was remarkably similar in form to the Falco. But only a prototype was built. SIAI Marchetti was so impressed with the SF.250’s potential as a military trainer that it purchased the manufacturing rights from Frati’s company, Aviamilano, and increased the power. The result was the SF.260, which first flew in 1966.
Since then, more than 1,000 SF.260s have been sold to the military services of 28 countries where they have been used as ab initio trainers (SF.260M), weapons trainers and attack aircraft (SF.260W) and coastal surveillance aircraft (SF.260SW). In addition, more than 100 civilian versions have been sold (of which 70 are in the United States) including some used by a few European air carriers as proficiency trainers.
In the late 1960s, SIAI Marchetti added leading-edge cuffs to the outer 20 percent of the wing’s span (to tame reputedly ill-mannered stall characteristics), added wing dihedral, increased the height of the rudder and vertical fin, incorporated a canopy jettison system and modified the wing with hard points to carry such external loads as drop tanks, rocket pods and launchers, 7.62-mm machine guns and small bombs. These changes resulted in the SF.260B.
Additional improvements, which included lagging balance (or servo) tabs on the ailerons to lighten lateral stick forces and a more sophisticated 24-volt electrical system, resulted in the SF.260C.
An improvement in the wing spar (which allows aerobatics to be performed at the maximum-allowable gross weight), a stronger nosewheel strut, and a short-stroke canopy jettison handle are the major differences between a C- and a D-model.
“I have an appointment with Shimon Shamir.”
The burliest of four armed security guards at the entrance to Israel Aircraft Industries turned and suspiciously ran his eyes over the two Americans standing before him. He paid particular attention to the Nikon camera slung casually over my shoulder.
“One moment,” he said gruffly. “Let me have your passports, and stand aside.”
He picked up the telephone, dialed, and after a short pause began speaking excitedly in rapid-fire Hebrew. Unable to understand this revitalized ancient language, I turned toward the nearest window of the security shack in time to see a TWA Boeing 707 thunderously departing Israel’s Ben Gurion International Airport.
As the roar of the turbines faded over the Mediterranean, the guard’s raised voice predominated once again. The only words recognizable to me during this end of the conversation were “Schiff” and “Nikon.”
Trying to maintain a facade of nonchalance, I studied what was visible of Israel Aircraft Industries’ vast research and manufacturing complex. It was no secret that within these buildings was the extraordinary scientific and technological talent responsible for developing the Kfir advanced combat aircraft, the Gabriel sea-to-sea, guided-missile system, the Dabur patrol boat, and a host of other sophisticated defensive/offensive devices needed to provide Israel with a strong military posture in the Middle East.
IAI began humbly in 1953 with only 70 employees working in temporary quarters. Since then it has emerged into a first-class aerospace organization that has been a major factor in the survival of the Jewish state during its brief, turbulent history.
But survival requires more than arms and armies. Israel also is fighting an economic war and desperately needs to remedy a serious trade deficit. This is one reason why IAI entered the fiercely competitive arena of manufacturing and marketing civilian aircraft. It began this ambitious program in 1967 by acquiring the Jet Commander 1121 from Rockwell Standard. Since then the business jet has been stretched and extensively reengineered resulting in the Model 1123 Commodore Jet, the Model 1124 Westwind, and eventually the Model 1125SP Astra.
Eager to manufacture an Israeli-designed aircraft, IAI opted to build a light, twin-turboprop transport for which it felt there would be a large market in developing nations. The aircraft was to have military, commuter, and executive potential. The result was the Model 201 Arava, Israel’s first indigenous design.
Named after the desert valley extending from the southern tip of the Dead Sea to the Gulf of Eilat, the Arava first flew in November, 1969 and entered production in 1971.
Five years and almost 50 military versions later, IAI entered the civilian market, and this was the reason for my visit to the Holy Land. Accompanying me was Jack Chrysler, whose expertise with a somewhat similar craft, the DeHavilland DHC-6 Twin Otter, would be helpful in evaluating the Arava.
Several minutes after the security guard had terminated his conversation, Shimon Shamir of the Arava sales force arrived to settle the matter of allowing my camera on the premises. Apparently Shamir had the necessary clout because the Nikon was permitted. This, we were told later, was a rarity. It was not that anyone was afraid that we would photograph some top-secret project. These were well hidden from view. What could be seen were a variety of military and civil aircraft from an assortment of distant countries undergoing major maintenance and/or modification. It was these activities, and for whom they were performed, about which IAI was sensitive and preferred not to have memorialized on film.
As we drove toward the flight line, I spotted a rather unorthodox looking aircraft. When I inquired about this strange machine, our escort responded coolly, “You didn’t see that.”
In the distance, however, I did see the Arava being readied for flight. It has the appearance of a bumblebee or a stubby cigar slung under a thick rectangular wing (take your pick). But what the Arava lacks in aesthetics is adequately offset wi
th rugged practicality.
The basic design began with a fuselage that had a circular cross-section because, even though this is more expensive to build than a rectangular fuselage, circular is more suitable for pressurization and/or stretching, possibilities for future models. Fuselage length and diameter were dictated by the need to carry a fully-armed jeep or to comfortably seat 20 passengers.
To accommodate such outsized cargo as a jeep, a large door was required. This resulted in the conical swing-tail that opens more than 90 degrees toward the starboard side of the fuselage. The geometry of the tail cone also minimizes drag and allows short-field takeoffs and landings at exaggerated, nose-up attitudes without risking a tail strike.
A high wing was chosen to keep the 3-bladed Hartzell propellers clear of ground obstacles and debris when operating from unimproved runways. Double-slotted, electrically operated flaps span 61 percent of the wing, which has a thick, high-lift, NACA 63-series airfoil. This leaves room for only relatively short-span Frise ailerons.
To augment roll control at slow speed, a scoop-type spoiler (like those found on Helio Couriers) is positioned forward of each flap. These are linked to the ailerons and each spoiler rises automatically and only when its respective aileron is deflected up more than 5 degrees.
The twin-boom configuration allows a truck to back up under the high elevator and park immediately adjacent to the Arava’s cabin floor, thus permitting straight-in loading through the open swing-tail. Or, a small vehicle can be driven up a portable ramp directly into the aircraft.
Airstairs were planned for future models, and the 113-cubic-foot cone of the swing tail would serve as an easily accessible baggage compartment.
An added benefit of the twin-boom configuration is that this places a rudder directly in the propwash of each Pratt & Whitney PT6A-27 turboprop engine. This increases rudder effectiveness at slow airspeeds and provides a respectably low minimum single-engine control speed (VMC) of 78 mph.
The Arava’s designers decided against retractable landing gear believing that the added performance would not be justified by the increased weight, cost, and maintenance. The idea was for the Arava to have maximum reliability, simplicity, and ruggedness, goals that appear to have been adequately met.
Shamir introduced us to Menahem Schmul, an Arava test pilot, who received his aerial baptism in the Israeli Air Force. Schmul did an about face, presented 4X-IBH (a new Arava destined for Mexico), and inquired abruptly, “Shall we fly?”
We nodded, and Schmul led us to the left side of the tail cone where we climbed a small portable ladder through the passenger door into the spacious cabin.
I was immediately impressed with the utility of the 7-foot, 8-inch-wide cabin. The Arava was the only commuter-type aircraft certificated under U.S. Federal Aviation Regulations Part 23 that was capable of 4-abreast seating.
Although Part 23 limits the Arava to a maximum takeoff weight of 12,500 pounds, IAI sought an exemption from the FAA to operate the aircraft at 15,000 pounds. This is the limitation observed by operators in 8 other countries where deliveries had been made. (During the Yom Kippur War, the Arava scampered in and out of short, unimproved strips while weighing in excess of 17,000 pounds.) During our flight, the aircraft was loaded with full fuel tanks (417 gallons) and sufficient ballast to establish a takeoff weight of 12,500 pounds.
Schmul buckled himself into the left seat because he was required to have access to the single steering wheel used to control the hydraulically-powered nosewheel. Engine start was conventional, and as we trundled toward Ben Gurion’s Runway 21, the simple pre-takeoff checklist was completed.
After being cleared to line up, Schmul extended the flaps to 25 degrees, locked the brakes and commanded 750 shp (783 eshp) from each engine. When the toe brakes were released, the Arava lunged forward, quickly gobbled up 600 feet of sea-level runway and was rotated positively to a jet-like attitude of more than 15 degrees. At 75 mph, the “bumblebee” clawed skyward at an extraordinarily steep angle.
After lowering the nose and retracting the flaps, Schmul established a more conventional climb at 1,700 fpm.
At altitude, Schmul demonstrated how comfortably the aircraft can be maneuvered at the lower limits of the design envelope. He then relinquished the controls to give Chrysler and me an opportunity to become more intimately acquainted with this Israeli workhorse.
The aircraft exhibits conventional and predictable handling characteristics, but flying the aircraft for long periods can be fatiguing due to the physical effort needed to move the control surfaces. The Arava is not flown with fingertips.
Since a heavy hand is needed to control pitch (especially during large power and/ or speed changes), liberal use of the electrically-operated pitch trim is necessary. Rudder and aileron tabs are also electrically activated. One wonders, however, how an Arava pilot would fare during an electrical failure because none of the trim tabs can be operated manually. At such a time, a pilot would be wise to cruise at the trimmed airspeed (the speed at which trim or electrical failure occurred) rather than change speed and be forced to exert considerable control forces for the remainder of cruise flight.
It is difficult to determine the precise flaps-down, power-on stall speed because the Arava does not stall in the conventional sense. When indicating about 50 mph (which seems to be the slowest achievable airspeed), the Arava simply holds its head high and gradually settles, all the while exhibiting exceptional roll control. It is difficult to imagine losing control of this forgiving airplane. A flaps-up, power-off stall results in a mild break at 79 mph.
To escape the beehive of international arrivals and departures at Israel’s main airport, we established cruise power at 5,500 feet and pointed the nose toward Jerusalem’s less-hectic traffic pattern. True airspeed was 165 mph. At 10,000 feet, the Arava cruises at 182 mph.
The wide, spacious cockpit is a comfortable working environment and there is ample room for the various instruments and controls, which are arranged neatly and logically.
The thoroughly rugged design of the machine extends also to the cockpit. All handles, knobs, and switches are heavy duty, built to last. The noise level is appreciably high, but the din is not as assaulting as in similar utility craft.
Once in the pattern at Jerusalem, it was difficult to devote total attention to Schmul’s instructions regarding short-field landings. The Western Wall, holiest spot on Earth for Jews, passed by on the right. Then there was the Dome of the Rock Temple, the Mount of Olives, Mount Zion, and a host of other biblical pylons that are difficult to ignore during low-altitude turns. But soon the windshield was filled with Jerusalem’s single runway.
Schmul dragged the Arava over the boundary at 60 mph with the immense flaps fully extended. Raising the nose imperceptibly, he allowed the aircraft to hit the tarmac (excessive flaring uses too much runway) whereupon he simultaneously applied maximum reverse pitch, stomped on the binders, and did a one-eighty on the tarmac. Total runway used was less than 600 feet. It was a convincing demonstration and removed any doubt about factory claims that the Arava operates routinely from a 950-foot-long, jungle strip in Ecuador located at 5,000 feet msl.
Chrysler and I took turns shooting touch-and-goes, and we found the Arava easy to maneuver and land using conventional techniques. Developing proficiency in short-field operations, we concluded, requires practice.
During a coffee break at Jerusalem, I finally was allowed to uncover my camera, but not without first being cautioned about where not to point it. Nearby, armed security guards ensured that I paid attention to this admonishment. Aerial photography in Israel, by the way, was verboten at the time.
Although IAI felt confident about penetrating the commuter market with the Arava, it was also planned to introduce the airplane to the bush country of Alaska and Canada. Perhaps it is there that Israel’s “Flying Boxcar” will have an opportunity to demonstrate its poten
tial as a versatile utility aircraft. The Arava can carry 17 fully-armed paratroopers or haul 2.5 tons of cargo from fields that would tear the landing gear from more fragile aircraft. On floats, the Arava would be quite a performer.
The aircraft was designed to fill a variety of civil and military roles, so if a customer wanted an Arava to be configured as an ambulance, a tanker, a gunship, a hunter-killer in anti-submarine warfare, or for counter-insurgency missions, IAI was willing to provide the hardware. It apparently performed those roles quite well.
To my list of Scandinavian favorites such asUrsula Andress, Ingrid Bergman, Britt Ekland and Ann-Margret (I am definitely showing my age), I now add another Swedish star performer, the Saab Safari.
This is a versatile aircraft designed to do it all. The Safari is aerobatic (+6 to −3 Gs), is rugged enough to land on a winding dirt road you would not want to drive on, can haul a litter case in its expansive baggage compartment, is easily convertible from tricycle gear to taildragger, and—if you are so inclined—can carry 660 pounds of wing-mounted, anti-tank missiles and 135-mm rockets.
Or the Safari can turn its swords into plowshares. In 1974, a small fleet of Safaris were flown to famine-ravaged Ethiopia to participate in a unique airlift. Taking off from small clearings at density altitudes above 10,000 feet, the Safaris air-dropped desperately needed food to remote villages accessible only by pack mule or helicopter. Approaching the village centers at 70 mph and 10 to 15 feet agl, the pilots dropped burst-proof sacks of grain and inner tubes filled with water to within a few feet of their targets. During this operation, each Safari delivered 7 tons of food per day.