I flew the Long-EZ to Longmont, Colorado (ID is 2V2) on 18th August for the Lyons Folk Festival (Marsha was attending songwriting school prior to the festival).
I lifted off from Dallas Executive at 09.15 CST, transitioned directly through the D/FW Class B airspace, and straight-lined it to Colorado, flying at 8500 feet throughout. No weather issues at all. However, I struggled the whole flight with CHT issues, especially #3 cylinder which consistently ran at or above 375 degrees on the CHT monitor. The last hour of the flight was rather bumpy as I hit early afternoon convective turbulence over the plains of Eastern Colorado, and I also found myself running into a headwind, which reduced my ground speeds to the 145-149 knots range.
I touched down at Vance Brand Airport in Longmont. After tying down the plane, I examined the prop and found evidence of a small amount of oil blow-by on one of the prop blades. An oil level check showed that I had 4.5 quarts left, having performed an oil filter and oil change immediately prior to the flight. I had therefore consumed around 1 quart on the flight - not excessive, but not stellar either. However, I am still losing a significant amount of oil in flight out of the breather tube under the wing root (the el cheapo air/oil separator that I installed last year is ineffective because it is too small, and it is currently mounted at the incorrect angle to provide any drain-back into the engine).
I headed back to Dallas on Sunday 21st August. When I arrived at the airport, there was the usual afternoon cumulonimbus build-ups over the high mountains to the North-West. These would probably give some afternoon showers at Longmont, but that did not bother me since I would be gone by then. What did bother me, however, was the unmistakable sign of towering shower clouds to the South and East. A phone call to WXBrief revealed plenty of gaps in the shower activity, so I decided that I would take off and rely on the speed of the Long-EZ to swerve around the weather.
I did not get going until 14.30 MST, which meant taking off at the worst time of the day from a density altitude perspective. I calculated the density altitude was around 7750 feet when I set off down the runway. With myself, luggage and 40 gallons of fuel on board, the takeoff weight was 1485 pounds. Not surprisingly, the plane did not exactly leap off the ground - I lifted off at around 3800 feet. However, once in the air, I was able to climb fairly smartly.
After negotiating the Denver Class B airspace, I initially climbed to 9500 feet. Initially, I realized that I had rain residue on the outside of the canopy that I had forgotten to clean off prior to departure from Longmont. I was concerned about this impeding my visibility; however, a chance encounter with virga as I left the Denver Class B airspace washed off the shower residue, leaving me with a nice clean canopy. (Memo to self - file this trick for possible future use).
Not being happy with being bounced around at 9500 feet, I turned on the oxygen supply and climbed to 11500 feet. 11500 became 13500 as I manouvered around a shower system South-East of Denver.
When I reached 13500 feet, the CHT on #3 cylinder was still around 375 degrees, despite the fact that I was running at low cruise - 2340 rpm. I decided to experiment with more aggressive leaning. My leaning technique had previously consisted of leaning until engine roughness appeared, then moving the mixture knob back around 1/4 inch. This time I leaned until the engine became rough, and then enriched the mixture by increments until the roughness almost disappeared. The results were dramatic. Within 5 minutes, instead of the normal CHT distribution (370, 355, 375, 355) I had a perfectly symmetrical reading on the CHT display, with all cylinders at around 360-365 degrees. Examination of the EGT display showed that #1 and #3 were lean of peak, with #2 and #4 probably slightly rich of peak.
At this mixture setting, the engine was not as smooth as at a richer mixture setting; however, it was not running roughly. More importantly, I was bowling along at 13500 feet, burning 5.4 gallons an hour, with a groundspeed of 162 knots. The lower CHTs allowed me to advance power to 2560 rpm, at which level I was burning 6.4 gallons an hour with a groundspeed of around 170 knots depending on the state of the tailwind, which was varying. The OAT was 42 degrees, but with the sun shining into the cockpit, my body was warm enough. The leaning process showed that the normal 20-25 degree difference I am seeing in CHTs is not due to different cooling on each side of the engine - it is entirely due to poor mixture distribution. The left-hand side of the engine (#1 and #3) is getting less fuel than the right-hand side (#2 and #4). I will be looking at possible causes for this asymmetry and how to address it in the next couple of weeks. I have a stock Marvel Schebler carburetor on the plane, and those are not renowned for even mixture distribution. If I can even out the fuel distribution, then I ought to be able to run the engine to peak EGT or even slightly lean of peak EGT. I doubt I can run any leaner without changing the fuel system to either an Ellison or fuel injection. I have no money for a significant change of that type right now.
I touched down at Dallas Executive 3 hours and 50 minutes after departing Longmont. No sign of blow-by on the prop, and the exhausts were a nice very light gray, except for #2 which was a lot browner. A lot of extra fuel is clearly being fed to #2 with the current inlet tract performance.
On this trip, I ran my new Lightspeed 3G headset for the first time with an aux audio source - a CD player. You need to turn down the CD player volume, but this worked really well, and the sound quality was a lot better than I expected. I was listening to the Pat Metheny Group's live Besancon rough-mix CD for most of the way up to Longmont. Can't get much better than that for in-flight entertainment.