SJ30-2: Trading Size for Speed

The Sino Swearingen SJ30-2 flies in the face of conventional business jet wisdom in almost every respect. While the rest of the industry is firmly convinced that passengers demand the greatest possible amount of cabin space and simply won’t endure a cramped cabin for very long, the SJ30 delivers coast-to-coast range at a cruise speed of 440 knots in an airplane with the smallest cabin in the category.

The belief that some people want to go as far and as fast as possible for the money, no matter how small the cabin, stretches back 20 years to when Ed Swearingen announced development of what he then called the Swearingen Fanjet. The airplane would take advantage of a brand new compact engine from Williams and would have 1,800-nm range cruising at Mach .72. The initial price in 1986 was set at $1.6 million, which was below the leading turboprop twins available at the time.

Swearingen has spent a lifetime in business aviation and is most famous for creating the Merlin and Metro turboprops. He also collaborated on the design of the Lockheed JetStar II, the Piper Twin Comanche, and was a protégé of Bill Lear, first at his avionics company and then at Lear Jet. Ed has even developed serious and complete designs for a supersonic business jet. Throughout his life, speed and range have been at the top of his list of airplane design priorities.

Ed then, and still, believes that business jet designers squander speed by using wings that are too big and cabins that are too large. A small, highly swept wing reduces drag. To reduce stall speed, and thus landing and takeoff speeds, Ed installs nearly full span leading edge slats and very large flaps, just like Boeing and the other big boys do. And as for comfort in a small cabin, in his view just put in good seats because people don’t want to stand up and walk around, anyway. They just want to go fast and far.

The 20-year odyssey from the Fanjet to the certified SJ30-2 had many fits and starts. For a time Ed teamed with Gulfstream and the airplane was called the Gulfjet. Later, he partnered with the Jaffe Group and the name was changed from the SA30 to the SJ30. Along the way a proof-of-concept airplane was built and flew in 1991. The airplane had significant anhedral-negative dihedral-that brought the wingtips alarmingly close to the runway. The SJ30 also had fuel stored between the engines which, when certification rules changed, was no longer permissible because if one of the jet engines burst the shrapnel could easily pierce the fuel tanks.

The solution was a fuselage stretch that got the fuel ahead of the engine rotor burst zone, and a wing span increase to carry the extra weight. The new airplane was named the SJ30-2, and in 1996 a consortium of Taiwanese investors bankrolled the company and it was named Sino Swearingen. Full type certification was achieved last fall, including for flight in icing, but the first airplane had not yet been delivered by late summer of this year. The price is just over $6 million, and the company has several hundred orders.

The SJ30-2 wing has only 190 square feet of area, only a little more than a typical piston single. But the airplane can weigh up to 13,950 pounds for takeoff so each square foot of wing is called upon to lift 73 pounds. As a comparison, the Cessna CJ3, the current leader in light jet sales, has a wing loading of 47 pounds per square foot. The small wing, along with 32 degrees of sweep, reduces cruise drag in the SJ30-2, but the tradeoff is higher stall speed, small fuel capacity and no place to put the landing gear when retracted.

The SJ30-2 has nearly full span leading edge slats that extend to increase the camber of the wing at low speeds. The slats, combined with large slotted flaps, reduce stalling speed enough so that typical landing Vref approach speeds are between 100 and 105 knots. However, the slats and large flaps add weight and complexity to the airplane, and reduce internal volume for fuel storage in the already small wing. Only 1,820 pounds of total fuel capacity fits in the wings.

The main landing gear fold in and aft to fit into the fuselage where they are covered by large doors when retracted. The main gear legs sometimes look a little spindly in photos, but they are actually very beefy. They remind me of an FA-18 landing gear in both design and their stout appearance. The SJ30-2 has dual wheels on all three landing gear, another unique feature among light jets.

The fuselage actually has two fuel tanks, one big one in the center and a smaller one forward. Fuel burns out of the big tank first to a preset level, then from the more forward tank, then back to the fuselage tank until it’s empty. The wings are kept full until all fuselage fuel is gone to reduce structural loads on the wings. Using two fuselage tanks is necessary to keep the center of gravity from moving far as fuel burns. The entire operation is transparent to the crew, and gravity moves fuel from the fuselage to the wing center section tanks so no transfer pumps are required. However, the airplane must be fueled from a single filler port located on top of the fuselage just ahead of the vertical fin. Line crew will not feel kindly toward the airplane as they perch on top of a tall stepladder to squirt as much as 4,850 pounds of fuel into the airplane.

SJ30-2 number three was lost in a maximum Mach certification dive test in 2003, and the NTSB split the blame between the airplane and the test pilot who lost control in roll. The design fix is a new aileron that is flat on the bottom and has a significantly blunted trailing edge. The new aileron remains effective to speeds beyond the maximum approved and the airplane successfully completed its maximum Mach dive for certification.

Another unusual feature is a rudder on the trailing edge of the ventral fin. This rudder is operated full time by the electric yaw damper system, and there is no need to turn off the yaw damper for takeoff or landing because it is not connected to the normal rudder.

The cabin of the SJ30-2 is smaller than you would guess from looking at the outside of the airplane. The space from the most aft cabin window to the engines is full of fuel, not cabin, so there is room for only four seats in club configuration. There is a side facing potty seat on the right side just inside the cabin door. Cabin headroom is several inches less than in a CJ or the Mustang. The cabin reminds me very much of the original Lear Jet 23 and 24 in terms of size and shape, which is no surprise given Ed Swearingen’s involvement with those airplanes.

The cabin is unique in terms of pressurization because it has 12 psi maximum, compared to around 8 to 8.9 psi for other light jets. That means the SJ30-2 cabin remains at sea level up to 41,000 feet while other light jets can only hold that level to the low twenties. To certify to that pressurization the fuselage had to be pumped up to 36 psi in testing. The low cruise cabin altitude certainly adds to a passenger’s physiological comfort and reduces fatigue on long flights, but the extra structure necessary to contain the pressure certainly adds to the empty weight of the airplane. Nobody at Sino Swearingen knows how much weight the extra cabin pressure adds because it was designed in from the beginning.

The cabin air pre-cooling is also unusual. In most jets the hot bleed air from the engines passes through an air-to-air heat exchanger mounted in the tailcone or engine pylon before entering the cabin. In the SJ30-2 hot bleed air circulates through the engine cowling inlet ahead of the fan to be cooled, which is a novel and compact solution to the problem. Extra hot air is circulated in the engine inlet ring when icing conditions are encountered, and bleed air also protects the wings. The horizontal tail has a conventional deice boot.

For some reason the SJ30-2 cockpit doesn’t feel quite as cramped to me as the early Lear Jets, even though the diameter is similar. Perhaps it’s the shape of the electrically heated windshields that don’t sweep back as closely along the side of your head as in the Lear. I even raised the seat off its lowest position, something I have never done in a Lear.

Like the other light jets the SJ30-2 is certified for single pilot operation if the pilot earns the single-pilot type rating. At this point the company is developing its own training program and plans to acquire a simulator in the future.

The nosewheel steering system is hydraulically actuated and controlled entirely by rudder pedal movement. In the normal mode, steering range is restricted to avoid an overly sensitive feel, but when you need to make a tight turn, you press a button and steering authority multiplies. I found it easy to guide the airplane on the ramp, taxiway and on takeoff and landing with no learning curve.

Though the stall speeds with slats and flaps lowered is modest, the Williams FJ44-2A engines only have 2,300 pounds of thrust each, so takeoff acceleration is not rapid and uses up the runway. For my first takeoff, with just two of us onboard and 3,000 pounds of fuel, the airplane weighed 11,800 pounds, considerably below its 13,950 maximum. But, with air temperature at San Antonio in the mid-80s, we needed 4,185 feet of runway for a balanced field takeoff. Takeoff speeds in the SJ30-2 are similar to other light jets and were 100 knots for V1 decision speed, 103 knots for rotation and 108 knots for V2 best angle of climb engine out speed. The airplane behaves predictably on takeoff, and after we were at least 400 feet above the runway I lowered the nose to accelerate to the 160-knot flap/slat retraction speed. Climb rates don’t match the spectacular performance of the CJ2+ and CJ3, but the SJ30-2 likes to climb at a higher indicated airspeed, typically around 230 knots, so it will fit in better with other jet traffic.

The controls in the SJ30-2 required what I would call a medium and not unpleasant force to operate, and roll and pitch forces are in pretty decent harmony. But the ailerons have an odd feel near the center that is often called “sticktion” because it is probably caused by a combination of control breakout force-stick force-and friction in the control system. The aileron controls, which are entirely mechanical, are as smooth as silk on the ground, but in flight the wheel wants to stick wherever you leave it even though it is slightly off center. Hand flying requires almost constant small tugs on the wheel to find the true center for the ailerons and keep the wings level.

The SJ30-2 has good stability in all axis, and steep turns are a breeze. It also will blow right through the Vmo indicated airspeed red line in level flight anywhere below the upper flight levels.

The airplane has a stick pusher that automatically shoves the elevator nose down when a stall is approached. A pusher is pretty common in T-tailed jets, but in the SJ30-2 it is a little different in that it will push the nose down before the stall in the clean configuration, but only activates after the stall with flaps and slats extended. I reached full aft stick with the flaps and slats out before the pusher would do anything, and had full control all the way through the stall.

But the SJ30-2 is not about slow flight, it is built to go places fast, so we saddled up for the 1,500 nm or so flight from San Antonio to White Plains, New York. The weather was good in New York, so we didn’t need to build in extra fuel for an alternate and could easily make the trip at high speed cruise. The airplane, number five and the first with a complete interior, weighs 8,486 pounds empty, a little more than expected for production airplanes. We added 4,060 pounds of fuel, and the three of us and our stuff weighed 700 pounds for a ramp weight of 13,180. We could have carried one more person and filled the tanks, just barely.

San Antonio had warmed only to 80º F but the required runway for takeoff was 4,636 feet, a lot of pavement by light jet standards and about what you would expect from some much larger jets. However, once the SJ30-2 was cleaned up and it accelerated, climb rates were around 2,500 fpm, despite well above standard air temperatures. After being leveled at 13,000 feet for about two minutes, the airplane reached 35,000 feet in 19 minutes after takeoff, again with air temperatures well above standard. The Williams engines have electronic controls, so there is no power management task on takeoff or climb except to put the thrust levers in takeoff and then the maximum continuous power (MCT) detents.

Climbing through 39,000 feet the air temperature dropped abruptly to 4º C below standard, and I leveled the jet at FL 410 just 25 minutes after takeoff. At MCT power it accelerated from the climb speed of Mach .70 to Mach .80 in just four minutes for a true airspeed of 459 knots on a fuel flow of 940 pph. The air kept cooling and soon the SJ30-2 accelerated to bump up against Mach .82. Those are amazing numbers for a light jet at 41,000 feet. With the air cooler than standard, and some towering cumulus ahead, I zipped up to FL 450 in five minutes where the airplane settled in at Mach .80, showing 446 knots through the air on a fuel flow of just 770 pph. The cabin altitude was less than 2,000 feet, unheard of in any airplane, much less a light jet.

The standard avionics in the SJ30-2 are the Honeywell Epic system, the same basic displays used in many larger jets. However, due to the long development program some capabilities such as detailed moving maps and weather in the cockpit are missing. The airplane also has a conventional warning and annunciator light panel instead of the engine instrument and crew advisory system (EICAS) found in many newer airplanes. EICAS issues alerts and annunciations in plain language on the multifunction display instead of using yellow or red lights with abbreviated identifications to alert the crew to abnormalities or emergencies.

We got no help from the wind, and even had 10 to 15 knots on the nose for much of the trip, but still had enough fuel to maintain maximum cruise power. Slowing to Mach .76 would have added several hundred miles to our range. As usual, New York area controllers had us down low a long way from the airport, but the SJ30-2 fits into the traffic flow perfectly. In fact, we had to slow down for other business jets ahead of us. The trip took 3+37 and 640 pounds of fuel remained in the tanks as we taxied in, enough for an hour of cruise at Mach .76. Our block speed was about 412 knots, as fast as the high speed cruise of some other light jets.

The SJ30-2 clearly delivers on its speed and range promise, but huge questions still surround the airplane. Foremost is what shape will the company that will manufacture it take? The present Taiwanese owners reportedly are seeking to sell the project, or at least to find a partner to share the still considerable cost it will take to go into real production. There are plans to build a service and support network, but they are not now a reality because no airplanes have been delivered. The first customers will have to act on faith, not a track record. And, of course, there are the cabin size and runway considerations. Certainly some-particularly owner pilots-will gladly trade the small cabin and longer runway needs for the speed and range of the SJ30-2. But for many the range exceeds the endurance of the occupants when you consider you could sit there for five hours.

The SJ30-2 is the first business jet to be designed and certified by a startup company since Lear Jet did it in 1964. Now the question is can this certified airplane be successfully manufactured and supported? Only time will tell.


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