In the high-elevation, dry-climate environment of Bend, Ore., technicians are busy putting the final touches on parts cured in freshly made tooling and finalizing processes to begin serial production of the Epic Aircraft E1000, a certified version of the Epic LT experimental-amateur-built high-performance single-engine, all-composite turboprop.
Transitioning an aircraft manufacturing program from making kits and assisting customers through completion to producing new airplanes for retail sale is an ambitious project, but the Russia-based owners of Epic have made the necessary investment to see the E1000 through certification and into production, according to Mike Schrader, head of sales and marketing. In 2012, he said, the owners opted to stop taking orders for kits and re-orient the company toward FAA certification. More than 50 kits were built, and the final two experimental versions are about to fly away from Bend.
Deposits for the E1000 are one percent of the $2.95 million price, and they are fully refundable. By the time inflation indexes are taken into account, the typical price will be about $3 million, he explained. Epic Aircraft currently has orders and deposits for 73 E1000s.
Epic is working with the FAA’s Seattle Aircraft Certification Office, which has gained significant composites experience, having worked with Boeing on the 787 program. The FAA helped Epic by adding resources to help keep the E1000 project on track. “They’ve been really good to work with,” Schrader said.
The Bend region has also long been a center of aerospace composites expertise and manufacturing. Epic’s facilities formerly housed Columbia Aircraft, manufacturer of the all-composite Columbia 400 piston single, which eventually became the Cessna TTx following Cessna’s purchase of Columbia’s assets.
Much of the testing of design-conforming parts for the E1000 is complete, including the wings and control surfaces, with some fuselage tests remaining. The target for certification is October or November, and once production certification is achieved—as close as possible to type certification, the company hopes—the goal is a production rate of 50 per year, Schrader added.
Prototype FT1 was busy logging flight time during AIN’s visit to the Epic factory in April. FT2 was in the final assembly stage and will be fitted with a fully conforming interior.
In-house Composites Manufacturing
For a small manufacturing company, Epic Aircraft is surprisingly vertically integrated. Its 200 employees do all composites manufacturing in Bend, build the steel engine mount, weave wiring harnesses and manufacture the interior, except for seats, which are provided by Wichita-based Millennium.
The composites manufacturing technique is similar to that employed by Cirrus Aircraft, which has achieved relatively high-volume manufacturing of the single-engine SR series and is ramping up the assembly line of the recently certified Vision single-engine jet.
After resin-infused pre-preg carbon-fiber is cut to the right shape, technicians lay the material inside and on carefully shaped tooling fixtures. A fuselage-half fixture, for example, looks like a giant bathtub, into which swatches of material are placed at points outlined by a highly accurate laser alignment system. Once all the material is laid out, vacuum bagging shrouds are placed over the carbon-fiber, and by sucking the air out of the bags, the carbon-fiber is held tightly inside the tooling while curing in a giant oven.
Even the wing’s spars are built this way, but they undergo another step: pressure removal of excess air using a tool custom-built by Epic technicians. The tool looks like a special wringer, and it rolls along and squeezes on the spar carbon-fiber material prior to layup to remove the excess air, maximizing strength while minimizing excess weight. The spar is one single piece from wingtip to wingtip.
All components are monitored via computer stations positioned along the assembly line. Raw composite materials must be carefully inventoried and monitored, to make sure they aren’t left out of cold-storage for too long. And an excess part of each composite component—a test coupon—is subjected to testing to ensure the component meets all the applicable standards.
Manufacturing of composite components for the production line has already begun, for those items that have already passed certification testing.
Composites manufacturing is a complex process, but the benefits are clear for an airplane such as the E1000. There are far fewer parts needed to put the E1000 together. Metal wings, for example, would need thousands of rivets, whereas the composite wing consists of front and rear spars, ribs and top and bottom skins joined without fasteners. Where the de-ice boots are glued on to the leading edge, instead of just building a smooth round shape and attaching the boot, the E1000 has a joggle on the top and bottom of the leading edge. This slight discontinuity neatly allows the boot’s edge to mate flush with the wing skin, making for a much more aerodynamically smooth installation.
The E1000’s (and Epic LT’s) aileron controls are unique, in that cables run all the way to the wingtip, driving a bellcrank and a pushrod attached to the outboard end of the flight control. This design maximizes fuel volume inside the wing, contributing to the airplane’s long range. The design also simplifies maintenance, because the bellcrank mounted at the tip of the wing is easily accessible after the wingtip has been removed.
The E1000 does have some design changes from the kit Epic LT, including a wing redesign that came somewhat late in the program and caused a delay. Engineers at engine manufacturer Pratt Whitney Canada recommended a redesign of the cowling’s air intake, widening the mouth and moving it closer to the propeller, and this improved intake efficiency by about 20 percent, Schrader said. The engine is a PWC PT6-67A thermodynamically rated at 1,800 shp, flat-rated to 1,200 shp, driving a four-blade Hartzell propeller.
The E1000 features a three-screen Garmin G1000 NXi flight deck and a Genesys Aerosystems S-Tec IntelliFlight 2100 digital autopilot. Radar, Iridium transceiver and radar altimeter will be optional.
The cockpit is spacious and comfortable, with an interesting feature not found in other airplanes: a kidney panel above the primary flight display is home to the angle-of-attack indicator, flaps indicator and warning lights, putting them directly in the pilot’s view. Twin USB ports are mounted on the left and right forward sidewalls. Switches are ergonomically designed to match the checklist flow. An automatic tank-sequencing fuel selector simplifies fuel management, similar to the system on the Daher TBM turboprop. “We spent eight months making a clay model of the cockpit,” Schrader said, before nailing down the design.
Epic Aircraft is holding off on revealing final performance numbers until closer to certification, but the kit Epic LT has flown 338 ktas at 28,000 feet, and Epic promises better than 325 ktas for the E1000. Schrader said that kit owners generally plan block speeds of 300 knots burning 60 gph, and this will be the same in the E1000. Range with a full-fuel payload of 1,100 pounds will be 1,650 nm. Maximum altitude is 34,000 feet.
For a pilot moving up from a smaller airplane, Schrader said, the Epic E1000 “is the last step. There is no need to buy a jet.”