Chris Prata wrote: >>My goal is to have a hot cross country KR1 that can cruise 200 which I know will require substantial power at the upper end of> the normal power ranges we see.<<
Kent Paser's "Speed with Economy" is the book Larry is trying to think of. And indeed, a very low-drag plane is the way to get there, and a KR-1 done right is certainly in that territory. Roy Marsh won a race at 197MPH in his turbocharged VW KR2S prototype, but I'm not sure if that race was a circuit or one-way with a tailwind. Also, his plane uses a NACA airfoil thinner than the RAF48. I assume you mean 200 MPH, and I assume by "cruise", you mean would do 200MPH wide open at 7500'. It's probably doable with 85 hp, but I sure wouldn't want to do it with a turbo. I don't know of many guys running them on VWs, but those that do don't seem to do it for long. of the 42 KRs listed at http://www.krnet.org/kr-info.html , only two have turbos, and I know Orma had a lot of problems with his. They're great for bragging rights, but not if you want to FLY a lot, rather than maintain a lot. I'm sure we'll hear from the few turbo drivers that are out there, but the are certainly a minority. VWs are being pushed hard enough as it is, without compounding things with a turbo. Short of going Continental or Lycoming, I think the Corvair is the key to flying reliably without a lot of maintenance headaches. Despite early problems with crankshafts, Dan Weseman's new 4340 crank and front bearing have now done what GPASC and Revmaster did with the VWs...practically eliminate broken cranks, I believe. Crankshafts are the only problem I ever had with the Corvair...everything else worked perfectly. Yes, they weigh 80 pounds more than the VW, but you'll spend a lot more time flying and less time rebuilding the engine! They don't burn any more fuel than a VW when throttled back (except for the slight drag penalty of the extra weight), and the extra power is far safer from a climbout standpoint...getting you up to altitude in a hurry if something does happen on takeoff. A Corvair is actually narrower than a VW engine and only slightly longer, and a standard KR "Revmaster" cowling will fit it. I'm with Larry on speed, but also economy. Whey you realize it costs 30% more fuel to run wide open than at cruise, you'll likely back off to cruise and get there slower anyway, at least I do! Another thing about the Corvair is the cooling. The things are absolutely covered with fins. There are all kinds of passages for air flow through the heads. Take a look at VW heads and there's practically no daylight in there at all...a fraction of the fin area that a Corvair has. There's a real difference in the ability to cool the heads and oil between the VW and Corvair, which I suspect is the major reason why valve jobs are routine on VWs, and rarely needed on Corvairs. Speaking of valves, the hydraulic valves on the Corvair are set with a feeler gauge on the bench at assembly, and the valve cover never comes off again until you rebuild the thing. Not true of the non-hydraulic VW valves, which require periodic adjustment. A KR1 with a Corvair would be a rocket, similar to what Richard Shirley has with his Jabiru 3300 powered KR1 (although his is almost certainly the slickest KR1 ever built). I think he can do 240 mph or so, but due to overheating issues, he can't do that for long. If it were me, it would be a Corvair, and I intend to back that up with my next plane. I already have one of Weseman's crankshafts in hand, and just about everything else needed to build my next one... Mark Langford ML at N56ML.com http://www.n56ml.com
