94 hours on Mark Langford's KR2S

94 hours on Mark Langford's KR2S

created Dec 11, 2005

It was gorgeous yesterday, but I didn't leave myself enough time to get the plane back together after doing some maintenance, so I finished it up just about sunset. I fixed an intake leak that was making the passenger's side of the engine run lean. I also replaced the exhaust donuts and shimmed the clamps to keep the stacks from leaking, and that enabled me to open up the heater duct.

The heater is just a store-bought stove from Wicks (it has an open slit on top to admit the air) with 2" SCAT tubing running to a 2" aeroduct flange on the firewall.

The other side of the firewall is a butterfly valve connected to a cable inside the cabin. [no, I wasn't flying when I took this picture!] This thing puts superheated air in a place that really warms your soul! I'll bet it's several hundred degrees. I guess I need to put a thermocouple on that and report back the specifics, right? Next will be a splitter that runs some of the air to a defroster, and some to the passenger. The remainder could be used to heat Detroit! A 1" line would have been quite sufficient, but 2" is what the butterfly and stove are sold as, so that works for me. Although I have a carbon monoxide detector in the cabin, now that I know how hot this thing is I'll probably make a stove of my own (similar to my carb heat stove on the other side) that takes intake air from the front of the cowling, just like my new oil cooler inlet (see below). This way carbon monoxide in the cabin will be much less likely. And in the summertime I'll just bypass the stove and connect tubing direct to the cowling inlet for outside cabin air. I also installed the $20 voltmeter that functions as an air/fuel meter so I could test it, so I was disappointed that I didn't get to test some of these things yesterday.

Today the weather was supposed to be pretty rotten, but it started out and stayed nice too, so I put about 2.5 hours on the plane in three different flights. It was about 30 degrees when I took off this morning, but the new heater took care of that. Although the knob travels about 2", a quarter inch out is all I needed to stay toasty. I could only stand "all the way" for about 30 seconds before I started considering spontaneous human combustion as a possible outcome of the experiment. It was really a carbon monoxide experiment, and the detector never changed color all day. It may be a cheap detector, but it does work (replace element every 30 days).

Early in the flight I started losing RPM and the engine ran a little rough, so I pulled out the carb heat and it eventually went away. My carb heat is good for a 40 degree increase in carb throat temp at full throttle, in 40 degree weather, so I guess that's good enough. I flew with carb heat on for the rest of the day except when at full throttle.

On my last test flight (still un-tweaking the idle mixture where I compensated for the intake leak) the EIS started flashing on takeoff, just about the point where I might have been able to stop or I might have rolled it up in a ball at the end of the runway trying to stop. I glanced at it and it was telling me "FuP", which is fuel pressure, and it was showing .9 psi (I have it set to warn me at 1 psi). I kept going and came back around for an immediate landing, but it looks like it's time to check my fuel filters. As far as I'm concerned, the EIS just paid for itself (again)! Of course you could argue that if I had a gauge I should have been monitoring it, but if I had a gauge for everything the EIS monitors, I'd need a panel three times as big as what I have.

The little LASCAR voltmeter worked OK as a mixture meter, but it did wiggle back and forth constantly, usually two segments, sometimes three). It tracks perfectly with my LED air/fuel meter, but it apparently needs some damping. I'll see if maybe a capacitor or something can remedy that when I see my EE buddies at work tomorrow. One thing to note about it is that the supply voltage is supposed to be 5v-12v, and since my alternator puts out 14.5v, I made a simple voltage divider out of two 800 ohm resistors to drop the voltage in half to 7.3 volts. I'd call it a sucess at measuring the output of an oxygen sensor, but it needs more damping.

Another change I made is I deleted the hideous oil cooler scoop from the passenger's side cowling inlet, and installed a 2" aeroduct right into the cowling below the inlet. This allows the passenger's side of the engine to run as cool as the pilot's side, and gives the cooler twice as much air. The EIS shows that now both sides are pretty much even in the CHT department, and my cowling is quite as ugly as before. The inlet directly beneath the spinner is the ram air intake. Keep in mind that in no way is this cowling finished, so it's a "work in progress". I got tired of working on the plane, and started flying it, so it's still quite rough. This should improve....if I can bring myself to stop flying it long enough to fix these little things...which is exactly what I'm trying to do. Still, this photo should dispell any misconceptions that I am a perfectionist!

I basically bummed around the local area at low altitude (scattered clouds at 4000') at various power settings, and did about 12 touch and goes at MDQ, one landing at 3M5, a 200 mph missed approach, and one pit stop at FYM, all with something like a 10k crosswind, gusting to 19 at one point. That was interesting, but not a problem, and I got better and better as the day went on. I think I used all of that rudder a time or two on rollout though! It might be notable that I was the only guy out there, when Sundays are usually busier around here. After all of that, I made the nicest landing ever at Hazel Green, but the wind was right down the runway for that one, and helped me make the shortest stop ever. Hazel Green is only 2700', so every landing is a short field landing. I've been coming in high and dropping the flaps last thing, so if I ever get in the position of having the engine quit on final, I can still make it. That works pretty good...far better than dragging it in with power, trying to see over the nose.

Bottom line is that thing is so much fun it should be illegal...

Contact Mark Langford (if you must) at N56ML "at" hiwaay.net (replace the "at" with @)

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