=============================================================================== LOG ENTRY - 20-JUL-2011 Matt Borland Flight: 8 - 20-JUL-2011 - 1.4 hr - S-Turns, Touch-and-goes Depart: KCOS ~1020 Arrive: KCOS ~1144 =============================================================================== It has been a while since my last entry. Since my last entry, I encountered some communication issues inflight with my instructor in flight #6, but we talked about it and now things are getting along much better. We had been doing several ground-tracking maneuvers, and small issues like identifying a shared point of reference were causing confusion while in the cockpit. In the meantime I have also become very accustomed to talking with ATC. It is now pretty straightforward. They are there to help you, and I realize now that for better or worse, they mess up more often than I do. This is not a slight against ATC, it's just a demanding job and there are going to be minor mistakes from time to time by both ATC and pilots. It has been warm lately, and though this doesn't pose a direct threat to our flights, it's a major consideration when planning flights in general. As air heats up, it becomes less dense and thus less capable of providing lift. As a result very hot temperatures can cause an aircraft to perform as though it is flying at a much higher alititude. Each aircraft has an operating ceiling and even below that ceiling performance degrades significantly. What hotter temperatures do is effectively lower that ceiling. A plane that has a ceiling of 17,000 feet under normal conditions may only have a ceiling of 12,000 feet. As a result, you need to perform a density altitude calculation to ensure that your plane can operate at the altitudes you plan to fly. This is a particular concern when you start at a high elevation. Colorado Springs Municipal is at approximately 6,175 feet above sea level, and some mountain airports are above 9,000 feet. My instructor is now trusting me to taxi along the tightly-fit planes in the aero club ramp, which is a good sign that my taxi skills are increasing. I remember veering significantly the first few times; now keeping the plane pretty well centered to the yellow line is becoming second-nature. I am also getting better at not hitting the brakes unless I want to; I can better control my feet's working of the pedals. At Colorado Springs Municipal (KCOS) there are three runways: 17L/35R, 13/31, and 17R/35L. Runways are numbered by the magnetic heading that they provide to a moving aircraft. So if you land at 17L, you are landing at approximately 170 degrees (south-ish) based on magnetic north. Note that this is different from true north; this sometimes causes runway designations to change as magnetic north shifts over time. The L/R designation is for the relative position of the runway to other similarly aligned runways. Since a runway can be entered from either side, description of the runway in general will indicate two directions (e.g. 17R/35L) that are separated by 180 degrees. However when landing or taking off, you are given only one direction (e.g. 17R). The direction is largely based off of the wind. You want to take off into the wind in order to provide the maximum amount of lift. Having a tailwind would 'take wind out of your sails' basically speaking and decrease lift significantly. A crosswind can affect your movement in various ways, but in general you want to minimize crosswind. As a result, most runways are aligned to provide a headwind based on prevailing wind patterns. Many larger airports have perpendicular runways to allow for more options if there are heavy crosswinds on primary runways. Runway 13/31 at KCOS has been under construction the whole time I have been flying. It is an example of a runway whose names have changed due to the magnetic shift; it used to be 12/30. This runway runs parallel to the military flight line and is primarily used for smaller aircraft. 13/31 is 8,269 feet long whereas 17R/35L is 11,022 feet and 17L/35R is 13,501 feet. Since 13/31 is now open, it is usually the preferred option for small craft using the military flight line. We taxied to 31 (so, taking off into the northwest) via taxiway Bravo 5, which places us on the runway with less than half the runway remaining. For a small plane like the T-41C, this is not a problem, because even with the heat and the short runway, not much is needed to take off. We performed a short-field takeoff, which is exactly what it sounds like: taking off using a minimum of runway. This involved setting the flaps to 10 degrees, then holding the brakes while throttling the plane up all the way. Once the max RPM is reached, then you release the brakes and let the plane zoom down the runway. My instructor estimated we took off in less than 900 feet of runway. This meant that even by starting with less than half the runway in front of us (probably less than 4,000 feet), we used less than a quarter of what was remaining to take off. Once aloft I followed ATC to guide us out of the airport region and to the practice area. There we performed a clearing maneuver and practiced a wind- drift circle, steep turns, and S-Turns. I am still having trouble keeping my altitude even, and also judging the angle of bank needed to successfully make an even S-Turn. Other problems I noticed are that in keeping my hand on the throttle (which you need to do) I inadvertently pull it back a little, causing the power to drop a little. Also, I'm not using the trim enough to decrease the amount by which I pull/push on the yoke. By not doing so, I strain the muscles in my arm and they pulse as they get tired. A day later, I'm sore in my forearm because I was pulling too hard on the yoke. Then we went back to the airport to perform touch-and-goes. To do so, you announce to approach your intention to perform touch-and-goes, and to remain 'in the pattern.' As you move around the airport, you are placed along a pattern in relation to the runway you are approaching. The patterns follow a rectangular shape including the runway as one of its sides. Patterns are designated as either right or left, indicating the kind of turn that the plane takes around the pattern (i.e. 'left' would be counter-clockwise and 'right' would be clockwise). Landing involves many aspects of flying coming together at once. You want to be approaching at a reasonable angle to the runway, and obviously you want to be aligned to the runway. However, among most other aspects, your airspeed is probably the most important single aspect. You need to maintain good coordinated flight and the appropriate airspeed for the aircraft and point along your approach. It is very fun to come in for a landing! You want to align your plane with the runway and head for the 'numbers' on the near side of the runway. In the T-41C, you are generally around 80 mph on your final leg. You can achieve this primarily through balancing power and flaps. Flaps are used to extend the chord line (length of wing from leading to trailing edge) and increase its angle. When performing a standard landing, you use about 20 degrees of flaps. Above 20 degrees can be used if you want additional drag; at 40 degrees it is akin to using airbrakes. You can feel the effect immediately. As you cross the numbers, just about as you hit the ground-effect of air, you flare the plane which helps burn off additional speed and allows you to position the plane correctly to let the plane stall and settle gently on the runway. You don't want to land the plane before a stall because you don't want the plane to become airborne again unexpectedly. In the case of a touch-and-go, you simply put the throttle full in and adjust the flaps as necessary, and perform a takeoff. Depending on what ATC has proscribed, you follow the pattern. In this case, we touched 35R, then after gaining about 300 feet, turned left and proceeded to the midpoint between the two 17/35 runways, then ran perpendicular to the runways, maintaining a climb to 7,000 feet (about 800 feet above ground level). Then we turned right into our base leg, then to final leg for 35L. We touched that, then followed a right pattern back through the center of the airport, and touched down at 35L again. Our day was about done, so on this go around we called ATC to let them know we were going in for a full stop, so they directed us to land on 13. We flew over my office on the pattern for 13, and my instructor flew us in for the stop. We took the plane to the fuel pit to refuel, and afterwards we had to wait to taxi as a couple of C-130s roared slowly by before we could head back to the aero club ramp. The plan next time is to just practice touch-and-goes, which should be a lot of fun. Hopefully I will have more to report on next week!