For the benefit of those who were not able to make the KR Gathering, and for those of you who may be interested in seating design, I've decided to share some of my experience with you that I've learned as a Sr. Project Engineer for a Teir 1 Automotive Seating Company, and how this applies to the KR. Depending upon what your KR Mission Statement reads, if you are wanting more performance, and flights are less than 1 hour, than by all means use the lightest weight option that you can find which is the sling seat per plans. If you mission statement reads something like cross-country VFR, flights longer than 1 hour... etc. Then you probably already have ascertained that the sling seat is going to be pretty inadequate for this mission. After speaking with a number of KR pilots, most of them agree and have at least placed some sort of cushion between sore back-sides and the sling.
Because of the required seating arrangement of the KR, the occupant is seated in the aircraft in a knee high position, very similar to a sports or race car. Because of the high knee point relative to H-point, this causes a number of seating comfort issues. 1.) The seat cushion (or sling)shape curves upward very abuptly at the rear spar. In medium to long flights this will cause the occupant to experience "tail burn" and numbness in the lower extremities. The Occupant's weight is always applied through the Ishial tuberosities in the hip. (The Ishial tuberosities are the bony horns of the hip that protrude downward) Because of the abrupt curvature of the seat cushion, even more weight is concentrated into this area of the body. 2.) In order to package the occupant into the small confines of a KR, the back or recline angle is high, and the back panel is flat. The human spine has curvature naturally occurring, it is NOT flat. Because of the high recline angle, more upper body weight is concentrated onto the shoulders, mid and lower back. This causes poor blood ciculation, and pressure points, which leads to back, neck and shoulder problems and fatigue. In short, it's uncomfortable. 3.) Sling seats have no way of absorbing vibration. Vibration is the leading cause of numbness and fatigue. 4.) No side bolsters or side support for the occupant(s). This causes the occupant to tense musles to maintain seating posture. This causes fatigue and discomfort. 5.) No armrests cause upper back and shoulder discomfort because the upper body remains unsupported. This also causes neck, shoulder and upper backache. Recommendations: 1.) Fabricate a fiberglass or CF seat like Mark Langford's or others have built. 2.) Automotive Comfort criteria mandates 50mm cushion and 35mm minimum meat to metal. That's 2 inches to any hardpoint in the cushion and 1.25 inches in the back. 3.) Incorporate some sort of suspension mat in the Ishial area of the cushion. Go to your local wrecking yard and get a wire or nylon web seat suspension mat from a car. Attach it with the same size springs. Insure that the fully loaded seat does not bottom on the belly skin and clears all routings. 4.) Incorporate some form of adjustable lumbar support in the back. This could be a "dogbone" shape of upholstered foam with velcro to attach it to the back upholstery. 5.) Incorporate cushion and back bolsters in either the foam or glass/CF seat frame. 6.) Incorporate curvature into the back. 7.) Incorporate armrests into the seat and side panels This is regardless of weather you have single or dual sticks, almost manditory for center stick. ===== Scott Cable KR-2S # 735 Linden, MI s2cab...@yahoo.com __________________________________ Do you Yahoo!? Yahoo! SiteBuilder - Free, easy-to-use web site design software http://sitebuilder.yahoo.com
