When I moved from Redondo Beach to Irvine I left the wonderful airplane rental community of Torrance Airport (KTOA), for the incredibly restrictive and stifling atmosphere of John Wayne Airport (KSNA). I checked out the flying clubs and the FBOs but it was not going to be very much fun to get checked out to fly let alone head out on a whim to take the waters on Catalina. I was a little bummed and started looking harder at the used airplane market. I put myself on the list for a tie down at John Wayne - 4 years later they called me to say I was up. Then I realized that there were all these neat merit badges I could earn. The FAA issued me a license to pilot a single engine land plane…under visual flight rules conditions…as long as the engine was not too big…and the wheels could not tuck up out of sight…and the third wheel was on the correct end.
Each of the caveats can be wiped away with more training. My brother got the engine size limitation removed by threatening to buy a Cessna. Actually he was really up front with the salesman and explained that next week he was buying a Diamondstar. The salesman said that what he really wanted was a glass cockpit 182. Well, Colin said he was pretty sure he did not want that. The salesman said he would be there in the morning with a spiffy new plane that would be irresistible. When Colin pointed out that he could not even act as PIC of the plane since the engine was larger than 200hp the salesman allowed that as he was a CFI he could just write that endorsement in Colin’s logbook after he had flown around in the 182 for a while. It really was that easy. Clearly not the merit badge I wanted.
After some consideration I decided on the tailwheel endorsement. Airplane generally have three wheels, though I have flown both two and four wheeled varieties. Those three wheels can come in two arrangements: either the single wheel can be in front of the pair of main wheels or it can be behind. Airplanes started out with just a pair of wheels and the tail was held up by a bent piece of metal. The planes were always landing on grass and the tail skid was just fine bouncing over the turf. When runways started to get paved, say 90 years ago when flying was becoming mildly popular, the shower of sparks from a tail skid on tarmac could elicit concern on the part of potential passengers. This led to its replacement with a little, tiny, hard rubber wheel. This tailwheel configuration is called conventional gear because it was in opposition to the with the single wheel was up on the nose. My goodness, all sorts of bad things, front smacking the prop to the plane hitting a bump and tripping on to its nose could be caused by that pernicious ‘tricycle’ gear. I think the picked ‘tricycle’ because the old timers could not get ‘damnfool’ or ‘newfangled’ to stick.
In any case, now it takes a special endorsement to take to the sky in an airplane with a tailwheel. There are really good reasons why this is so and they primarily have to do with momentum. An airplane with tricycle gear has the center of mass somewhere in front of the two main wheels, this keeps the nose down on that misplaced wheel sticking down from the region of the engine. With conventional gear the center of mass is behind those two big main wheels and if it were not the plane would nose right over on to its prop. So, what is the big deal? Well, once an airplane gets going the placement of that center of mass is important. If the tail starts to wander left or right in a tricycle gear airplane the center of mass up in front of the mains will tend to pull the tail back towards the middle. In contrast, a when the tail swings in a conventional plane the center of mass swings out that same way and tends to keep the rotation going. Imagine riding a bike with a big pail of water on a long stick out in front. Hit the brakes and the pail pulls you forward, but if that long stick is trailing out behind, when you hit the brakes the bucket is apt to come swinging around one side or the other. That fundamental instability is a real knock on the conventional gear, especially when combined with a little aerodynamics.
The wing generates lift as air moves over it. More airspeed means more lift, in fact much more because lift goes up with the square of airspeed. Well, when the tail of a tailwheel airplane starts to swing around, propelled faster and faster by the instability of the center of mass being behind the mains, the wing on the outside of the turn is moving a lot faster than the wing on the inside. In fact, the plane is often rotating around one of the wingtips, which means the airspeed is nearly zero. So...no lift on the inside wing and a good deal of lift on the outside wing. What happens? The plane flips on its back or at least tilts the outside wing up until the inside wing hits the ground. This is called a ground loop and while loops are normally something you might recount with great glee this type only happens to the other, less skilled pilots. Except for that time when it was not at all your fault.
More training is needed to fly tailwheels, that is all there is to it. John Wayne has an excellent aerobatics school run by an autocratic, but basically nice fellow with very firm ideas of how people should fly, learn to fly, and think about flying. One thing they do very well is teach the tailwheel. For one thing they have a lot of different tailwheel types. When I was there they had five types and perhaps eight planes. This is eight more than almost any other training company I can name. I flew three of these types and they would not have signed my endorsement without at least two. If I were a bigger ticket sort of guy I could have flown the last two, a Pitts S2 and an Extra once I had the endorsement in hand. But, to start they put me in the most docile tailwheel they could find, the American Champion Citabria 7ECA (type CH7A).
The Citabria was a stronger, faster version of the Aeronca Champ, itself an attempt to improve on the oddities of the Piper Cub. The idea was to sell a short field plane that could hold two and be completely aerobatic. In fact airbatic citabria is a palindrome. Walking up to the plane I was really book smart, I had read the POH extensively, and about tailwheels in general, but nervous about my lack of practical experience. This was not just my first tailwheel plane but the first made of cast off rags and wire, the first where they threw the copilot seat in the trunk when they realized it would not fit next to the pilot, and the first with a wooden spar. I mean really, the whole dang wing is supported with wood. Termites eat it, it burns, it rots – what kind of fool build an airplane wing out of it and then sits the airplane outside? I was nervous. Also, the doors were essentially a pillow case strong on some coat hangers, with some saran wrap so you could see what you would fall on when the wing spar gave way.
About that tow bar. There is none. You just grab the back end of the plane and push it to move side to side and push on a wing strut to get it rolling forward. Once out of the parking spot we did a preflight that included looking at a lot of bits and bobs that might either rot or come untwisted, causing great issues with the aerodynamics of the plane. Once all was inspected and found to be in as good condition as it was designed to be, we climbed in with the instructor in back. I’ll get this out of the way early: this plane is not for folks who take great comfort (probably misplaced) in smooth metal or upholstery. The seats are really camp chairs wired in to the birdcage frame. I am pretty sure the cushions were leftover from a college football pep rally, though I was surprised they were not emblazed with a school mascot. The controls and instruments are basic, but as I settled in to the seat I realized that nervous was giving way to excited. This plane is designed to fly, not carry folks around in comfort, just fly. There is something very, very cool about that.
The forward visibility of taildraggers is always a potential issue on the ground, but the Citabria has a good enough view over the nose that the only reason for S-turns while taxiing is so that I can learn S-turns. And to keep the stick back. In the very light winds the plane does not even feel a little bit squirrelly and by the time I am lined up and ready to go I am nothing but excited. The engine is small, but the tandem seating makes for a narrow, low drag fuselage, and that spiderwork of tubing covered with fabric is far lighter than an equivalent metal plane. So, while the Citabria does not leap off the pavement it does get moving smartly and we are airborne and headed for the aerobatics box in short order. This is another airplane with a control stick; I have a hard time imagining aerobatics with a control yoke. I am mostly learning tailwheel operations, so we will soon go back and practice landings, but first I get to do what every kid who has ever thought of flying wants to do…fly the plane upside down. All the planes I have flown until now can do aerobatics, but they are not only not designed for it, but it is both illegal and ill advised. It is far too easy to screw up and overstress the airframe.
This plane is made to loop and roll and hammerhead. So that is what I do. The instructor is wonderfully tolerant. I just tell him what I want to try next and then I move the stick and rudder in the directions I think will accomplish that. It mostly works, but when I ask to be shown the difference between a aileron roll and a snap roll I get a chance to see how wonderfully precise the Citabria can be in the right hands. When we return to the pattern I do both wheel and three point landings and neither one seems particularly difficult. There is little wind so there is not much opportunity for hilarity on the roll outs, but in general I am impressed with how docile and clean this little plane is. The more landings I do the more I see why there are some folks who only fly taildraggers. The plane has to be flown even while on the ground. When it takes off you have to lift the tail, build up speed then rotate. It turns a simple takeoff into something you have to pay attention to: it is aviating. The Citabria may not have all the muscle of its bigger aerobatic cousins, but it convinced me to keep at the tailwheel endorsement. Next up the Decathlon…same plane with a bigger engine and a metal spar. After the jiggling I gave my guts in this plane I am quite sure that I do not want to experience whatever G-forces lie between the wooden and the metal spar.
No comments:
Post a Comment