Jet Design Utilizes Speedy Time-to-Market Manufacturing Processes

Several aircraft builders are in the process of developing smaller, highly specialized jets designed to fly into smaller, underutilized airports - bypassing the larger, busier hubs and helping to alleviate the overcrowding witnessed by many of the bigger carriers. These jets are faster and safer than turboprops, can land on runways of only 2,500 feet and have become quite attractive for those who need to travel short distances. One company has seen the future of this type of air travel and is trying to make it theirs, bringing some very interesting engineering ideas to the table in making their jet quicker and cheaper - promising to deliver the jets to customers for less than $1 million.

The Project

Friction stir welding is a technique that creates stronger part bonds than the traditional riveting techniques used by most aircraft developers. This type of manufacturing process decreases the amount of labor needed for constructing the jet, which allows the aircraft to be kept at an affordable price. All of this combined helps get the jet out to the consumer that much quicker, claim Eclipse officials.

"Time-to-market is extremely important to us and not just in the competitive arena, where that is just one component," says Dottie Hall, VP of marketing for Eclipse Aviation. "Mounting an aircraft development program is an extremely expensive proposition, so any time that you can take out of the process is a lot of money saved in the program. One big issue we tackled is that by investing heavily in computer modeling, we did more comprehensive design earlier in the process before we began building the real thing. Historically, aviation engineers would build something and see how it worked, then would try something else if that did not pan out. In the computer CAD environment that is really unnecessary."

Friction Stir Welding
One unique aspect of the development of the Eclipse 500 is the use of a "friction-stir" welding device in the construction of the real aluminum aircraft. Eclipse once explored the possibility of machining large parts of the fuselage, but dropped the idea when it found that the welding process was four times faster than automated riveting. So, rather than riveting or bonding the aluminum airframe components, friction stir welding offered a process in which a rapidly rotating pin creates frictional heat that bonds to the aircraft aluminum. The benefits of utilizing this process include stronger, lighter joints that eliminate the need for thousands of rivets. This results in reduced assembly costs and time.

The process itself has been used in several other aviation applications - such as the manufacture of Delta rockets for the U.S. Air Force - but this marks the first time that the process has been used on metal as thin as aircraft aluminum. Friction stir welding gave the Eclipse 500 a smoother exterior skin surface unlike rivets, which, even though small, can disturb the airflow of the jet.

RCO Engineering, Inc. (Roseville, MI) - a product development services company - was responsible for the interior design of the Eclipse 500 and for the construction of two life-size, fiberglass mock-ups of the aircraft. Since RCO was allowed to set the theme for the plane's cabin, its designers did a freehand sketch, then scanned it and cleaned it up in Photoshop. RCO then converted to Unigraphics for solid modeling, which gave them the surface data that they needed to CNC cut tools and make carbon fiber and fiberglass lay-ups.

Networked data from the customer to the RCO design office to the RCO CNC department provided real-time data communications between RCO's office and Eclipse. Jpegs and illustrations were created from Unigraphics software files and then e-mailed around for approval. Comments were then inserted by various parties in both companies, allowing updates to designs and approvals to happen within hours. This was truly an integrated and connected system from the customer to the designer to the machines making the tools.

Other Rapid Technologies Used
Both companies - in order to improve and streamline the creation of the mock-ups - used 3-D CAD data to quickly CNC cut molds and do fiberglass lay-ups of all of the aircraft's components. Automotive CAD design technologies like Alias/Waterfront were used for digital styling, which was then turned into data for making the real jet. Rapid tooling techniques were used to cut high-density foam, low-cost tooling with a sprayed-on surface for re-cutting, and finishing and polishing to release the lay-ups. In some cases, SLAs and SLSs were used to incorporate late additions, which were added with only a couple of days left. Creative backside attachment methods were utilized since engineering had not yet completed the attachment details of how these components were going to be attached.

"SLS and SLA components were fabricated to allow Eclipse the ability to make last minute additions to its jet. The technology we found to be key in helping us do this last minute work was the compatibility of our CAD systems," says Norm Starr, director of sales and marketing for RCO.

Obstacles and Advice

• The final instrument panel attachment to airframe.
• The final top pad over the instrument frame.
• The definition and attachment to airframe.
• The exact definition of what components in the instrument panel would be standard and optional.
• The exact placement of some items on the instrument panel that are still evolving due to natural ergonomic studies and reviews.

RCO also created "backside features" and attachments to mount the components into the mock-up - which are non-visible or hidden fasteners that are frequently attached or fixed to the panel backside and then pushed, screwed, velcro'ed or secured by some means to the airframe. Now, Eclipse has begun the process of making a real aircraft and entering the production stage of the program.

"If I had any recommendations to share with other companies it would be for them to get the definition of what is being built up front before tackling a project. Making your priorities understood by the customer at the outset and agreeing upon a time frame and work plan is critical," says Starr. "This wasn't always the case when we were working on the Eclipse mock-up. We were working on a trade show deadline for Eclipse, so the option of changing the date to get a better idea of what they wanted was not possible. This is why it is important for companies working on tight deadlines to obtain clearer visions because a clear vision results in higher quality products, and quality products mean continued business."