Civil and military customers

Aviation Technology Group's high-performance Javelin jet resembles a mini-F-22 Raptor for a reason — in addition to general aviation customers, the company is targeting the military trainer market, says company founder and chairman George Bye. The Javelin completed its maiden flight on Sept. 30, 2005, and aerodynamic flight testing is currently underway. Order deposits to date total 106.

The sleek design has the smallest cabin dimensions of any VLJ, with tandem seating for two — one passenger sits behind the pilot. Wingspan is 23 ft/7m, length is 36 ft/11m, and baggage payload is about 200 lb (90.7 kg). Service ceiling is 45,000 ft. Weighing about 6,200 lb (2,812 kg), and powered by two Williams FJ-33 turbofans, the Javelin will cruise at 520 knots (600 mph). "It will be the fastest general aviation certified plane in the world," Bye claims.

The plane's all-composite airframe was designed with CATIA 5 from Dassault Systemes (Paris, France), coupled with MSC.Nastran and MSC.Patran finite element modeling software from MSC.Software (Palo Alto, Calif.). The prototype was fabricated by Composite Solutions (Scapoose, Ore.), using Toray's Torayca T700G 12K unidirectional carbon/epoxy tape and T700S 12K noncrimp, plain-weave fabric for the fuselage, wing and empennage structures. ATG's chief structural engineer Dick Ulman says that several prepreg systems are under consideration for actual production aircraft: "We're looking at a number of different materials. The Torayca material is a strong contender." While some form of automated fabrication may be used — tape placement is a possibility — once full production is underway, Ulman says that, for now, parts are being hand layed up, in both open female and male molds, and cured in an autoclave.

The airframe includes a combination of solid laminate and cored sandwich construction. The short, raked wings have a three-spar design, with the forward spar close to the leading edge, a second in the middle and the third supporting the aft wing. Unidirectional carbon tape is layed longitudinally along the spar axis to form the spar caps, and biaxial ±45° woven material forms the spar webs. The prototype has a two-part fuselage, with a top half and a bottom half, but Ulman says the production version might be made differently, with cylindrical segments.

Part count reduction is a big program driver, and labor-saving ideas are being considered, such as integral sub-assemblies or modules. Complex tools with removable aluminum mandrels are under development says Ulman, to enable assembly of the ribs, stringers and skins for "one-shot" autoclave cure. The integral design eliminates secondary bonding and metal fasteners, says structures engineer Bruce Gillit. "A high-integrity bonded joint is a much better solution, in our opinion, and produces greater structural integrity."

Both Nomex honeycomb and Degussa Rohm's Rohacell polymethacrylimide (PMI) foam are being investigated for sandwich structure in the fuselage and for control surfaces, but Ulman says trade studies are still ongoing and a final material decision hasn't been made. Other "interesting" challenges include the two air inlet ducts for the jet engines, which have compound curvature and can't be produced in one piece because of assembly issues. Another is the heat produced by the engines in the tail area. A high-temperature solution like bismaleimide (BMI) resin isn't feasible because of cost, says Ullman, so some sort of insulating blanket or heat shielding material will be needed in the engine compartments and around the engine exhausts to protect the composite structure.

The military trainer version of the Javelin was exhibited at this year's Paris Air Show, and it received a "warm reception," says Bye. ATG has partnered with Israel Aircraft Industries (IAI) to produce the Javelin Mk20 AJT military trainer version, which comes equipped with ejection seats, much more complex avionics and radar, and other upgrades. The company predicts that future military demand could lead to a wide variety of applications, like homeland defense surveillance, for example.

Price for a civilian Javelin is about $2.8 million, and will run about $5.5 million for the trainer version. Bye thinks the air taxi market will grow slowly, because of airspace and traffic integration issues. But, he's banking on the tens of thousands of general aviation pilots or business jet owners who want to move up to a high-performance plane. "The civilian Javelin is about the same size and same price as a medium-twin turbo aircraft and has a ton more performance — there's no comparison," he concludes.