An interesting program founded by Rick Adam in 1998. With a successful background in new technology companies, Rick elected to put up much of the capital needed to launch development of a 6-place push-pull piston made from composites.
As part of his promotional launch package, he issued a white paper providing his justification for going with a composite configuration. It is reprinted here in full with comments on his reasoning.
|ADVANTAGES OF CARBON COMPOSITE CONSTRUCTION
There are several important advantages of building an aircraft from carbon fiber composites:
On paper, Adams comment sound good, but in practice, flawed.
|1. Structural Tailorability- The fibers in the composite fabric are able to be oriented in directions that are best for the design. In essence, designers can orient the fibers of the composite material in the direction of strength/
stiffness needed. This is a limitation of metals, which has the same properties in all directions. The flexibility allows designing a more efficient structure.
|1. Really a disadvantage. Aircraft see a wide variety of loading conditions. Positive gs, negative gs, gust loads, maneuvering loads, landing loads. Most aircraft structural components are subjected to tension loads, compressive loads and torsional loads. It is important to have structural properties that work in all directions.
|2. Corrosion and fatigue resistant- Composites are not subject to corrosion from natural or man made elements and have high resistance to fatigue damage. That is, unlike metals, composites lose little structural integrity from ongoing use and can have unlimited airframe life.
|2. There is no magic bullet.
What happens to the strength of the composite structure when the airplane sits on the tarmac in Tucson on a hot summer day then climbs through the thermals and their 50 ft/sec gusts?
|3. Lightweight Strength-The advantage of composite being lighter than metals is usually misunderstood. Composites indeed have lower density than most metals, but for structural stability and with other design reasons, composite airplanes usually weigh the same as metal airplanes. By using a greater amount of lighter material, structural parts like skins are relatively thicker. The result is a stiffer more solid aircraft, which is less than susceptible to hangar rash. It is common for the light skins of small metal airplanes to buckle (like a soda can) while under normal flight conditions. This is not the case for a composite airplane. A composite aircraft has the feel of a more sturdy airplane, and also has better dampening (less vibration transmission), making a more soundproof structure.
|3. Some realism here as Rick Adam may have been sending a signal when he was quoted in the Sept.9, 2002 issue of Aviation Week, We werent trying to do anything radical or magic with
carbon (material). Adam said, We also werent trying to get every spare ounce out, so we have more material in there than is needed from an absolute safety point of view. But Id rather be safe than sorry.
By how much are they going to miss their 4,200# empty weight projection?
And, Adam may want to check with Beech on the difficulty in controlling sound in composite fuselages. And Beech does not have two big Continentals on either end of the fuselage.
|4. Better aerodynamics and aesthetics- Composite manufacturing more readily allows complex curved surfaces with fewer joints, seams and rivets. The result is finer design and superior aerodynamics, adding to the look, feel and performance of the aircraft. In contrast, metal requires very expensive tooling or machining to get similar-shaped parts.
|4. Better aerodynamics but if it weighs more all those gains are lost.
Rick Adam comes from outside the industry and he does not have a clue on what it would cost to tool a sheet metal airplane. His comments on costs are pure speculation.
|5. Simple assembly- Using composites can make aircraft assembly more simplified, since many of the fasteners and small parts can be replaced with larger, more integrated structures.
|5. More speculation.
Those promoting composites often make this claim with no basis of fact. It is something they want to believe and often repeat it among themselves as reassurance.
See Myth #2