Embarrassment? Hell, that KR thing of us is making us embarrassed for one reason or another every single day! Luckily, we have days of pride to balance that.
On my second flight with the new engine, Norman Stapelberg was helping me, and we were in a big hurry to test that engine (bad start, always!). So, I did the pre-flight while he was still fiddling with the engine. Somehow, I ended up forgetting the pitot cover. I realized that when it was too late to brake, so I took off, switched the GPS on, and started working on the GPS ground speed. Normally, I could have landed my KR2 with no instruments at all, because I knew the correct attitude and engine noise. But this was a new engine. And the 2.4 liter was much more powerful than the previous 2.0 liter, so I battled to get my approach speed right. At the same idling speed and with the same propeller, the engine pulls harder, which is something I can't understand. On the second attempt, I corrected the speed by a mere 5 Kts, and it changed the whole picture. So, you're right. Accurate and reliable airspeed indication is critical with a KR2, ESPECIALLY during flight testing. Then, the engine died during the landing roll, as soon as the airspeed bled. Wouldn't idle. These air cooled engines have a different behaviour when hot, and it was probably running too lean. lessons learnt: 1 - Never hurry to fly, especially for flight tests 2 - Run your engine for a long period before the first flight, until it is as hot as it will be at the end of a normal flight, to make sure that it still works fine at all RPMs when hot. 3 - For good measure, also set your carb fairly rich. Serge Vidal KR2 "Kilimanjaro Cloud" Paris, France "Mark Langford" <[email protected]> Envoyé par : [email protected] 2005-05-25 15:11 Veuillez répondre à KRnet Remis le : 2005-05-25 15:12 Pour : "KRnet" <[email protected]> cc : (ccc : Serge VIDAL/DNSA/SAGEM) Objet : KR> Re: airspeed calibration Serge wrote: > Which ASI did you settle for? I'm almost too embarrased to answer that question. Last night I'd decided to go with a $422 TSO'd version (I got zero input from anybody) based on nothing more than the fact that it was TSO'd. But then I noticed Vans is selling the cheapo UMA with markings installed and started wondering if maybe they weren't so bad after all, so I ordered one from AS&S (after gaining assurances that I could return it with no restocking fee if it's not accurate). The number is 10-02870 and it's about $143. If it's not accurate, I'm returning it and ordering a TSO'd one. I just heard from John Martindale that he bought the same UMA as I did, at the same timeframe (7 years ago), and that there was a whole rash of bad ones at the time! Maybe I'll be luckier this time. Thanks for the comment on the calibration website. That link that I provided to the EAA 1000 website had a few pages of calculations that I muddled through for two hours before I finally gave up. Although I sucessfully calculated my pressure altitude to about 8 significant figures (never mind that my altitude came from a GPS that was plus or minus a few feet) I had an absolute pressure of 11,0000 psi or something. So I dug around on the web and found the numbers that I posted, and they matched the numbers in Jim Wier's Kitplanes article. His method was a little more cumbersome, so I guess I improved on it slightly. You can do this same test without even taking the ASI out of the plane. Just hook the tubing to your pitot tube. It doesn't mean your whole pitot/static system is checked, but it'll give you an idea of how accurate your ASI is. Although I don't know diddley about flying KRs yet, I DO know that an accurate indication of airspeed is vital for first flights if you are not an experienced KR pilot! Mark Langford, Huntsville, Alabama see KR2S project N56ML at http://home.hiwaay.net/~langford email to N56ML "at" hiwaay.net _______________________________________ Search the KRnet Archives at http://www.maddyhome.com/krsrch/index.jsp to UNsubscribe from KRnet, send a message to [email protected] please see other KRnet info at http://www.krnet.org/info.html
