Early Overcast Means a Poor Soaring Day?
C. G. Prince
I made a personal best flight on a "closed-course" flight yesterday (7/28/07)-- some 231.87 miles (373.16 km; OLC Classic), with an average speed of 39.57 mph (63.68 km/h). As JC Cunningham, my crew says, "Good crew makes you go farther ;-)". The day was 3:5:6, meaning I had three hours of sleep the night before, I drove five hours total (2.5 hours each way on the Duluth - Osceola trip) to and from the airfield, and the flight was 6 hours in duration. I say "closed-course" in quotes because I did have both upwind and downwind legs, but didn't make it back to the airfield. More on this below.
I started off the flight with a plan to fly a 250 mile task, with the first turnpoint to the NW of Osceola (OEO), about 10 miles South of Little Falls, near the Mississippi River, a second turn point of Chetek, WI, and then finally returning to OEO. I had in mind to fly my first leg downwind, then head upwind in the strongest part of the day, then to have a downwind leg later in the afternoon (presumably the weakest part of the day). Launching from OEO, I found that the winds aloft were out of the South, so I changed my plans and headed North. I first flew to Rush City, then to Hinckley, then to Moose Lake. Thermal strength was great most of the way to Moose Lake. I had what was probably my strongest thermal, early in the day. At 1:01pm and 4,277 MSL, and around 13 miles NW of OEO, I circled in a thermal until 1:06pm, with a resulting altitude of 6,622 MSL, climbing some 2345 feet in five minutes with an average strength of 469 feet per minute. I flew 10 turns in the thermal. Here's an image of the climb. While the averager on my Tasman vario indicated a higher rate of climb, clearly that wasn't the complete story considering the thermal from its base to the top.
I made it to Moose Lake at about 2:15pm, and was making good time. This was about 1 hour and 45 minutes into the flight-- and in the air I was making speed similar to what I could have driven on a trip from OEO to Moose Lake in my truck! After Moose Lake I decided to head to Mora, MN. I wanted to return to OEO, but a direct flight from Moose Lake to OEO covers quite a bit of forest, with few off-field landing possibilities. Flying from Mora to OEO would cut most of that forest off. Much of my flight from Moose Lake, to Mora, then back to OEO seemed to have have me finding weaker lift. Looking back at my flight trace, most of this weaker lift was around Rush City at around 3pm. At this time, I got down to 3,000 MSL, and was eyeing up Rush City with thoughts to landing there. In my first-ever cross-country flight a few years ago (on 7/13/03), I had overflown Rush City, but I have never landed there. This flight, however, was not the day for that. I managed to work some weaker lift, and escape Rush City to the SE. I had my highest climb of the day about 5 miles SE of Rush City, getting up to 7275 MSL. At that point, I was at the SW forested location and bend in the St. Crois River on the way from Rush City to OEO. I arrived just North of OEO at 4:45pm with plenty of altitude, and feeling like the flight wasn't yet over. I radioed to JC on the ground to see if he was game for me to add a further leg on the flight-- and continue towards Durand to the SE. He was up for it, so I continued my flight to the SE.
Making it to Baldwin, WI, I saw what appeared to be an elongenated balloon in the air. My first thought was that it might be a toy balloon that someone had released. But, it wasn't ascending. Continuing to look, I saw more of these shapes, in different colors, and realized these were unpowered paragliders-- there was a parachuting operation at Baldwin. I'm pretty sure this is the first time I've seen parachutes from the air; they were very pretty, and looked fun! At Baldwin, at 5:41pm, I made the decision to turn back to OEO, and in retrospect should have made this decision a little earlier. At Baldwin, I started seeing the cumulus deteriorate. The edges of the cumulus were what one sees about 1/2 hour or so before they disappear. Perhaps as much as 1/3 of the cumulus were showing these signs. It appeared that the day was starting to deterioriate. Also in retrospect, looking back at my altitude flight trace, I pretty much only lost atitude leaving Baldwin. I made it to New Richmond, and was going to land there, but found some weak lift, and saw a cumulus cloud North of New Richmond. Wanting to make it back to OEO and to add to my mileage for the day, I continued to this cloud. There was effectively no lift to be found though (10 feet per minute doesn't really count!), and at 6:22pm, I abandoned hope that I'd make it back to OEO. I was fortunate that in my attempts to work the last bit of weak lift, I had seen what appeared to be a private grass airstrip, running East-West. It seemed about the right width, and reasonably long, so I headed that way. I was at nearly 2300 MSL, and had around 700 feet of breathing room before having to enter a landing pattern. I flew over the East end of strip, appraising the field. It continued to look like a private strip. I saw no wires present that would interfere with my landing. Aloft, there was a light wind from the SE, so I decided to land to the east. I flew a left hand pattern, and used up about 2/3 of the strip before stopping. This strip does have a bit of East-West undulation, but overall it was well-kept and a pleasure to land on. Here is an image giving the location of this private airstrip. I've marked the runway in red, given that it is not particularly apparent from the image. The field is about 2 miles East of the North tip of Cedar Lake, and 10 miles SE of OEO. It's lat/long coordinates are: N 45 13' 56", W 092 31' 25". The river to the East of the strip is the Apple River. (You can ignore the blue flight trace on the image, and the word "Finish"-- these are OLC annotations). The strip does not appear on the Green Bay sectional.
Climbing out of the cockpit, I gave JC a call on my cell phone. I'd not made it back to my starting airfield, but it had been a great day. Later, JC and I kept talking about our surprise that the day turned out so well, with the substantial amount of overcast that the sky started off with. Walking to the end of the private strip near where there were some houses, I heard at least two birds of prey giving some kinds of screeching calls-- perhaps territorial defense? These sounds provided a fine epilogue to my flight. Over the phone, I gave JC lat/long coordinates, and found a local person to give him directions. Shortly, he was there, and we derigged on the side of the grass strip. After driving back to OEO, and parking my trailer in its hangar, we had an enjoyable meal in town, celebrating the day's activities. The evening was beautiful-- with a full moon to mark the end of a great soaring day. Thanks to Mark Robotti for being tow pilot on short notice! The OLC link for this flight is here.
Here is a brief analysis of this flight in terms of my goal for the day. I made approximately 232 (OLC miles) for this flight and had been planning on 250 miles. How can I get to my 250 mile closed-course goal? Well, one issue is that the day was relatively short. If the lift would have continued to 7pm or beyond (e.g., as they sometimes do in the Spring), I could have added substantially to my mileage. However, I am also certain the efficiency of my flying can be improved. There were numerous point that I took thermals that were too weak. One way I should be able to improve my average speed is to be more disciplined in only taking thermals that are above my criterion thermal strength for that altitude and time of the day.
If you see the day starting with overcast, don't be so sure that it won't turn out to be excellent for soaring! Even though on the drive down from Duluth I was starting to plan what I would do if I didin't fly (to head down to the Asian district of Minneapolis to do some grocery shopping), I was mistaken and didn't need these plans. Persistence paid off, and I'm very glad I didn't prematurely decide not to fly.