Page 7 - Volume 20 Number 7

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x, With
Microsteps To Microjets
to land the aircraft precisely.
The altimeter reads 9,500 turbojet engine was a modern, onto the airshow scene in May,
MSL, but I’m only 3,000 feet or so above New Mexico’s high-desert ter-
rain. If I crane my head over my shoulders, I can see the tips of my aircraft’s ruddervators. Yet, I’m still required to do clearing turns before beginning my maneuvers, so I do. I’m about halfway through my Permanent Letter of Authorization (LOA) checkride in the SubSonex microjet, and while I’m alone in the solitary cockpit, I’m still being monitored. One video camera records my view inside and outside the cockpit, including the instrument panel and controls, while another uses a wide-angle lens to capture the entire profile of the diminutive JSX-2, as seen from the right wingtip. On the ground, the DPE monitors my radio
ucalls and waits abeam the runway’s touchdown zone to assess my ability
e
clean-sheet design, with exception- al thrust-to-weight ratio and fuel economy. Unlike earlier microjet en- gines, it incorporated computerized digital control, an integrated starter/ generator, recirculating lubrication, and spark ignition. People noticed. Soon, the TJ-100 became very desir- able for small manned aircraft and drones. Previously-built microjets, struggling with engine reliability for years, began to convert to PBS engines. Other applications that had been waiting for just such an engine began to move from imagination into reality.
Jet Gliders: An Oxymoron Or Soul Mates
An early adopter, Bob Carlton of Desert Aerospace, engineered the installation of a TJ-100 onto the top of his Salto aerobatic glider. He’d been performing airshows in sailplanes for many years and had previously installed retractable RC- jet engines, attempting to eliminate towplanes. That proved only margin- ally successful. But, when he burst
2008 with his self-launching Super Salto Jet-Sailplane act, he knew he’d finally found the right engine. What he didn’t know is that it would be so successful he’d go on to convert a two-seat motorglider (a Comp-Test TST-14 Bonus) from piston power to a retractable TJ-100 engine. The conversion created a self-launching training glider that didn’t suffer from the anemic climb performance plaguing nearly all self- launching gliders (especially at the high density altitudes common at many popular gliderports). With the cooperation of both PBS and Comp- Test, the engine installation included computer components and software developed to make it as pilot-error resistant as possible. For example, safeguards ensure the engine cannot be retracted/stowed until the full shut-down sequence is complete, including a two-minute cool-down, even if the pylon switch is selected to DOWN with the engine running.
The newly-christened TST-14J BonusJet motor glider has become
Tiny jets have been around for decades. Until recently, however, flying examples have been essentially limited to novelty air- show acts and one-off aircraft that were originally designed for piston- power. Their jet engines were mostly converted Auxiliary Power Units (APU’s) or up-scaled RC- model engines. While the former suffered from poor power-to-weight ratio and high fuel consumption, the latter lacked reliability and operational convenience.
Then, in 2008, a Czech company with decades of experience build- ing military-grade APU’s introduced something different, something game-changing. The PBS TJ-100
a Bonus!
The SubSonex is not a true V-tail. It’s actually a Y-tail, with a small stub-rudder below the ruddervators. Together the three surfaces
provide excellent yaw control and crosswind manners.
JULY 2016
TWIN & TURBINE • 5