Wednesday, July 7, 2010

Flying a Cessna Original

Flew in an interesting plane today. Dubbed the "Rainmaker II" by its owner, N8574B is an original Cessna 172. As always, click the pictures for a larger, higher quality version. The older, 1970s models I teach in are, roughly, the 15th versions (L, N, and P models), and the ones produced today are S models. 74B isn't any model, its an original, manufactured in 1958, and it isn't what we would consider in "mint" condition, with a few stickers and a rattle-can paint job. The owner lives in Alaska, but his nephew lives here, and wants to finish his pilot training that he started about 7 years ago. Of course, he wants to fly the uncle's plane, which will be much cheaper (has to buy about 5 gallons of $4.50/gal gas per hour vs. a $90/hour rental).

There are many differences between the Skyhawks I usually fly and this early-model bird. First of all, the engine is a 6-cylinder, but rated at the same horsepower. Second, the plane is a lot lighter than the later models. Since the engine is flatter, the cowling (nose) is flatter, and so is the instrument panel. The windshield is bigger, and there is better visibility out the front, it is really cool. The tail is more square, which doesn't affect flight characteristics, but is very noticeable in this picture, which has a newer Skyhawk tail in the background for reference. Also, the plane sits much higher off the ground, so the sight picture is a little different and thus the landing also. Flaps in the school planes are electric, and when you select the flap lever, it takes several seconds for them to deploy or retract. In 74B, there is a big manual lever on the floor, much like the emergency brake handle in a car. Its really cool because you can go from zero to full flap much more quickly, and take them out quickly also. The final difference about the old plane is the way a vacuum is generated to power some of the gyroscopic instruments. In newer planes, there is an engine-driven vacuum pump to provide a vacuum source, but many older planes have these:
Each of these two tubes is called a venturi. As air passes through the narrower part, it speeds up, and as the speed of a fluid increases, the pressure decreases (this is Bernoulli's principle, one of the same effects that create lift in a wing). This vacuum is connected to the gyros. This is awesome. Cessna 172s are certified for spins, but normally can't be spun because there is no way to legally disconnect the gyros. If you spin the plane with the gyros powered, the bearings wear prematurely, which is especially bad for planes certified for instrument flight - where the 3 gyros are the only way of controlling the plane. Since this 'hawk has venturi-power (they aren't very good, especially at low speed) and is not certified for IFR, and the gyros are ancient, nobody cares if the plane is spun.

Spins have the reputation of being dangerous, but it would be more accurate to say that unintentional spins are dangerous, and spins when it is unclear who is flying the plane are dangerous, and spins in planes not certified for them are dangerous. Otherwise, it is a relatively low-stress maneuver for the airframe, and if loaded and certified, the planes are capable of entry and exit completely reliably. All pilots practice making the wing stall, which just means it hits the air at too high of an angle. Spins are simply when one wing is in this "stalled" condition and the other is creating lift, so that the plane rotates. It is a lot of fun to glide with the engine at idle, slowly pull the yolk back to the stop, wait for the nose to begin to break, hold it, and shove one rudder pedal to the floor. The nose drops off to one side, falls about 70 degrees below the horizon, and begins to rotate about one revolution per second or two. To recover, you just push the other pedal, let the yolk come forward, and bring the nose to the horizon. Lots of fun.

Well, because of all these differences, I was told to take the plane out by myself and get used to the way it flies before I try to teach in it. I went through the papers, read the checklist, examined the instrument panel to find the switch and lever locations, and fired 'er up. Despite the differences, it is just a Skyhawk, and the first circuit around the pattern went very normally and culminated in a near-perfect landing. OK, checkout complete, the plane flies almost exactly the same, so I headed out to the practice area, got radar services, and climbed to about 5,000' above ground level. Spins in the 172 are something I've wanted to do since I got spin instruction last November in preparation for my instructor rating, and I have come to the conclusion that (as long as safety is carefully considered) spins are pretty much the most fun maneuver that is legal in a non-aerobatic plane. After a couple each left and right, I headed in for some more landings. That was when I discovered the joy that is manual flaps. Had fun getting to know the plane, and did some grass operations and engine-out practice (the plane glides much worse than the later models).

After an hour of the most fun I've had in a plane for a long time, I headed over to the fuel pumps. Before the flight, the left tank had 13 gallons and the right tank had 10 gallons, 23 total. After the flight of 1.7 hours, the plane had 16 gallons in it. 7 gallons cost me $33.50. When is the last time anyone got almost 2 hours of free, fun, solo flight for less than $40? I don't know, but it sure is cool when it comes around. I'm excited to start teaching the nephew in his uncle's aerial classic, sans the spins of course.

The entry in my logbook for this flight was the last one on the page. While adding the columns, I realized I just hit 900 landings and 400 flight hours. I have flown about 100 hours in the past 8 weeks, when I started this job. Up to this point in my life, I have managed to average about 100 hours per year. Now that is something to write home about.

1 comment:

  1. I agree on all counts about spins. Glad I had the chance to do them during my primary training as they are a ton of fun. That's a sweet old bird, too!