I was looking through the archives for something else when I stumbled across this message that I sent July 28th, 2002, and I think it's good enough to post again...
KRnetHeads, The subject of "keeping it light" is a recurring theme on this list, and it certainly has its merits. Building it light allows you to yank and bank and generally cut it up in the sky, and to land slowly and climb quickly. There are those that liken it to a fighter plane or a small sports car, and that's great if that's what you want. I'm a sports car fan too, but I have to admit that they'll usually wear you out on long trips. Fortunately, technology is allowing small cars (like my GTI) to run like a rocket, handle well, AND track straight down the road with minimal effort, so you CAN have the best of both worlds, with a little careful thinking. So let me present the heavier side of the subject. Like Don Ried said, doing the wingskin with a layer of glass on the inside and two on the outside yields a skin that won't delaminate and flop around in the breeze. Troy tells me that he was happy that he had to build new wings because his top wing skins had detached from the foam and they would balloon upwards during flight. This is on a carefully constructed plane less than ten years old that is always hangared! So the choice is build it light, or rebuild it often! Personally, two layers on the outside and one on the inside is exactly what I did too, and I'm quite happy with it so far. My wings have been stashed in every corner of the basement, and don't have a scratch on them yet. My Corvair engine is probably going to weigh about 60 pounds more than a typical VW Type 1 engine, but it will also put out almost twice the power! Adding 50 pounds to double my power to weight ratio is a worthwhile trade, to me. We've heard testimonials from pilots that adding a 180 pound passenger cuts maybe 5 mph from top speed, although I'm sure it impacts climb rate and landing speed more significantly. With 135 hp engine, I don't think I'm going to have a problem with climb rate. And I get the peace of mind of knowing that my crank isn't going to break, my case isn't going to wear out, and if one of the six cylinders goes dead I probably won't even notice! I put an electrical system and a starter on mine, mainly because I don't want to be one of those guys who shows up on the news explaining how my plane got away and tore up several hundred thousand dollars worth of other airplanes, or is expected to crash in Kansas when it runs out of fuel. Another side "benefit" of my heavy plane is that the wing loading will be higher, making it less susceptible to bouncing around in light turbulence, yielding a smoother ride at higher speeds. I've also added a few inches to (and pounds) to my horizontal stabilizer and fuselage length. The improved stability will be worth it, in my book, by making long trips less tiresome, and reading maps less hazardous. On the other hand, you won't catch me doing any wild aerobatics either, but that's not why I'm building a KR. Right now I'm in the middle of adding "useless" NACA ducts to the bottom of the fuselage right behind the cowling. What this "dead weight" will do for me is smooth the flow of engine exhaust and cooling air back into the airstream, making my plane more efficient and faster. Do I need that that weight? Nope, but I think it's a good tradeoff. Both my canopy and aft deck have roll bars built in to provide protection during a rollover. It's extra weight, but I feel better having it there. My big split flaps will probably cost me 8 or 10 pounds, but they will also allow me to land my "heavy" 700 pound plane at a slower speed than a plans-built plane could. This is important to me so I can land at my father's farm on his very smooth 3600 foot sod strip, or allow a slower touchdown in the event of an off-field landing. I widened mine a few inches, and that will cost me a pound or two, but now I can carry a passenger in comfort for long distances. I have nav lights, landing lights, and strobes, so I can operate at night if I want to, and to be more visible to others during the day. It's just a safety thing, and I like it that way. I have a transponder so I can operate in places where I couldn't if I didn't have one. I made my forward and aft decks completely removable. In five minutes I can have the entire top of the airplane GONE, totally open for inspection and maintenance. I think I'm going to like that a lot, later on. I didn't like fuel in the cockpit, or the way the CG goes aft as it burns off from a header tank, so I built wing tanks instead. Two wing tanks weigh more than one header tank, but I'm happy with the improved fire safety and the fact that my CG will barely move from full fuel to fumes. And wing tanks built in the outer wings take the load off the wing attach fittings, another bonus. I have an electric fuel pump as well as a mechanical one. I like the dependability of a carburetor with a float bowl that runs on a finite fuel pressure setting, rather than depending on something as fickle as ambient pressure and gravity. When fuel pressure depends on head pressure, a small change in attitude can make a large difference in flow and mixture. But those pumps cost me a couple of pounds. I added Oil*te bushings to my tail hinges, so they'll last much longer than the steel-on-aluminum design shown in the plans. But that's going to cost me another few grams. I could go on, but I'm sure you get the picture. Like almost everything else in life, building a KR is a compromise. You decide which ones to make, but it doesn't mean that others are building theirs wrong, since they are not "per plans" and tip the scales a little higher. I'm building a personal "time-machine" that will allow me to go long distances quickly. I want it to last a long time and require little maintenance, so I can get on with my next project. You're welcome to build yours to fit your needs as well... Mark Langford, Huntsville, Alabama mailto:N56ML "at" hiwaay.net see KR2S N56ML at http://home.hiwaay.net/~langford
