A $60,000 Personal Jet
By James Grahame
Sonex Aircraft, LLC is the brainchild of businessman and kit designer John Monnett and Mechanical Engineer Pete Buck. Monnett's industry credentials are legendary -- he was inducted into the Experimental Aircraft Association's Homebuilders Hall of Fame in 2001. Buck, on the other hand, draws up the plans for Sonex designs "in his spare time." Scared yet? Don't be. Buck is a lead Engineer at Lockheed Martin's famed Skunkworks. He worked on the F-117 Stealth Fighter and X-33, among others.
Since 1998, they have introduced a range or piston driven light aircraft that have proven popular with kit enthusiasts -- the two-place Sonex, Y-tail Waiex and the Onex single-seater.
Now they've unveiled the jet-powered SubSonex.
The "pre-prototype" SubSonex JSX-1 has been flying since August, 2011. It looks like its piston relatives, except that instead of a propeller, a surprisingly compact PBS TJ-100 turbojet engine is mounted on the top rear of the fuselage, directly in front of the distinctive Waiex Y tail.
The TJ-100 puts out only 247 pounds of thrust, but that's enough to propel this tiny 400 lb aircraft through the air with decent performance. Upon takeoff, the JSX-1 is capable of climbing 2,000 ft/min at 140 mph. Its cruise speed is 170 mph, while its Vne is 197 mph - the same as its piston-powered siblings.
"In essence, flying a small jet is like driving a car that only has fifth gear. Don’t expect jackrabbit starts. However, unlike a propeller—which loses thrust with increasing airspeed—the jet just continues to push. Its thrust even increases slightly with speed. The takeoff roll begins at a stately pace, but increases steadily to a rotation speed of 80 mph, at which time you become fully aware of the diminutive four-inch main wheels and lack of spring suspension. A slight pull on the side stick and you’re airborne.
With no pounding pistons, pulsing prop, or propeller slipstream, the instant transformation from an overspeeding wagon to intense smooth is nothing short of inspirational. The acceleration continues, quickly pushing the little craft to its best climb speed of 140 mph. A little nose up and she’s rocketing skyward at nearly 2,000 feet per minute. Raising the nose gear further enhances the silky smooth ride.Once airborne, there are no surprises. With the SubSonex’s light weight, ample control surfaces, and short wings, handling is understandably sporty, but not twitchy. With the pilot’s full-forward position and no engine or propeller up front, visibility through the bubble canopy is superb. With a good noise-cancelling headset, the experience is a bit glider-like, except for the speed and climb rate."
The prototype flight test program was promising, but there were a number of things the designers wanted to change. The most glaring issue was the cockpit, which measured 24" at the pilot's shoulders but tapered to a mere 20" at the control panel. A second prototype is already under construction with a cockpit that measures 24" wide throughout. The new shape will improve the appearance of the nose, which will be extended and taper more gently. They plan on replacing the manually retractable nosewheel with electrically retractable nose and wing gear. A ballistic parachute will be installed immediately behind the cockpit, eliminating the need for the pilot to wear one during flight.
Of course, jets burn more fuel than piston aircraft, especially at low altitude. The Subsonex is no different - it consumes 18 gph at 10,000 ft. With a 40 gallon tank, that should give you enough fuel for a 350 mile trip with a VFR reserve.
While the Sonex team is obviously excited about this little aircraft, they have no plans to put the aircraft into production quite yet. Their immediate goal is to complete the new JSX-2 prototype and put it through its paces in the air. If they're happy, SubSonex kits could eventually hit the market for as little as $60,000.