I have not posted a reply to the KR network in a long while, but I think that it is time to break my silence. I have wing tanks it the outer panels of my project. I have not measured the capacity yet but they are on the order of 20+ gallons . . . each. That goes along with the 4+ gallon header tank. Yes, I will have something like 8 hours of tankage for my O-200, more if I throttle back to increase the range.
How many people know that Ken Rand's KR-2 was retrofit with wing tanks in the outer panels? There was a very bad photo published in Sport Aviation in the late 70's or early 80's that showed one of Ken's wings opened up for the work. He had removed the bottom wing surface from rib to tip between the spars. I do not remember how large the actual tankage was. I suspect that it was most of the available volume. I never published that photo on my web site due to the poor quality. With turbo VW, increased tankage, and portable O2, he did travel very long distances. I think that he could go from California to Sun-n-Fun with one fuel stop. One big point is ... just because you have it does not mean you need to use it all of the time. There is nothing wrong with taking off with less than full tanks. If you are going to be flying for one hour, why take along eight hours worth of fuel? Three will be more than enough. (Please don't remind me about the three most useless things, one being fuel in the truck. That is entirely too simplistic) To those of you who ask how I can consider sitting in a KR for more than a few hours, please note that I have made a real seat. When I started building my project I knew that I did not have any desire to sit in a canvas sling seat. My seat is contoured for my backside and I can sit in it for as long as I want. It is very comfortable even without padding. I will have a relief tube running down the back of the left gear leg and exiting at the trailing edge of the wheel pant. (I plan on testing it out for the first time at a low altitude over a certain person's house) Random thoughts on wing tanks: Air loading on the spars is reduced by carrying fuel in the wings. Landing loads on the spar are increased, but they are significantly lower than the air loads. If you land hard enough to damage a wing due to fuel load, then something else will have broken, like your landing gear or firewall. Negative wing loading while just sitting on the ramp is so trivial that it need not be considered. Installation in the outer panels is very easy and there is no interface with controls or gear mounts. It does require one extra fitting in the fuel line compared to a stub wing installation. Fuel burn will cause CG to shift forward, this is a good thing. With a large header tank, it goes the wrong way. My transfer system is very simple, both tanks drain to a common low point behind the baggage area. One fuel pump to the header tank. An auto transfer based on level switches and a manual override. The header tank is vented back to one wing tank and wing tank vents are arranged to give a slight positive pressure. The transfer system has a green power-on light and a yellow light for transfer-in-progress. Transfer is started on a low level switch and secured on a high level switch. There is a separate low-low switch that turns on the bright red light. There is a separate header tank level gauge that only comes on-scale when I reach the low-low level. On a loss of transfer capability, I will have 45 minutes of fuel I would never consider having a large header tank. The advantages of having fuel in the wings far outweighs any drawbacks. Don Reid mailto:donr...@erols.com Bumpass, Va Visit my web sites at: KR2XL construction: http://users.erols.com/donreid/kr_page.htm Aviation Surplus: http://users.erols.com/donreid/Airparts.htm EAA Chapter 231: http://eaa231.org Ultralights: http://usua250.org VA EAA State Fly-in: http://vaeaa.org
