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Landings: How-To: HOW TO FLY A J-3 CUB

HOW TO FLY A J-3 CUB
by Dagley Reeves

[Introduction][The TAXI][The TAKEOFF][Common Mistakes]
[Air Work][Landing][Crosswinds][Emergencies]
[Conclusion][NTSB Accidents]

THE TAKEOFF

Probably the first thing noteworthy is that nothing has changed with respect to forward visibility, you can't see the dern runway. For the first hundred feet or so, your going to have to learn how to keep the nose straight by looking off to the side. This takes a little practice and if it starts out bad, the rest of the takeoff roll is going to be a ride to remember. Kinda like backing up in a pickup or van when you can't see behind you and you have to use side vision to stay straight. Another good analogy regarding tail wheel aircraft is comparing ground operations with backing a trailer. It is important when backing a trailer to make small correction early because as we all know, if it goes too far it gets jackknifed and you have to start all over. Same thing with takeoff in a tail dragger. Small correction early. The smaller and earlier, the better. Just like a trailer, if the airplane goes too far, you can't get it back and what results is the proverbial GROUND LOOP. Ground loops are not a good thing because even at the slow speeds the Cub operates, they usually result in major damage to the aircraft and the pilots pride.

Here is how it goes: Pilot lines up on runway and picks reference point off to one side. I use the line between the grass and the runway edge. Advance power slowly but steadily keeping the nose straight. Pilot makes corrections at the first indication of trouble. At slow speeds, obviously, when the rudder is not very effective, you move the rudders a lot. As the plane picks up speed start decreasing the amount of input. Allow the plane to accelerate and apply slight forward pressure to the elevator. The tail will start coming up and will tend to seek equilibrium at the proper spot for takeoff. I used to wonder how it was possible to balance the airplane so precisely on the wheels for takeoff. I thought it would be like trying to balance a pencil on the end of your nose. It's not hard at all because that is really where the plane wants to be. Think about the angle of the wings. At first, the wing is tilted up. As air start going over it, it pushes the back of the wing lifting it. If you pushed too hard on the stick, the nose would go away from you trying to point the wing down. Now, air is hitting the top of the wing pushing it back level. This is the easy part, so it's really not a balancing act at all. The hard part is keeping the airplane straight reference to the runway centerline because now some other things start happening.

As you already know, during takeoff, the airplane wants to pull to the left. This has to do with the twisting moment of a clockwise turning engine, the fact that the descending blade is operating at a higher angle of attack producing more thrust on the right side of the engine, the corkscrew path of the air as it strikes the rudder and something not well understood by most pilots, gyroscopic forces. Aerobatics pilots know a lot about gyroscopic forces because they use it to accelerate their maneuvers. If you ever at an air show watch the performance and you'll notice that hammerhead turns are always done of the same side, snaps rolls always the same direction as well as torque rolls.. Briefly stated, gyroscopic precession is a force which acts 90 degrees to the applied force, in the direction of rotation. Huh? Forget that, do this. Take the front wheel off of your bicycle. Hold the end of the Axel in one hand with the wheel in from of you as if it were a propeller. Spin the wheel clockwise from your perspective. Now, as the wheel is spinning, point the end of the Axel slightly downward (simulating the tail of your airplane coming up). Notice that there is quite a pull to the left. The applied force was toward the ground, 90 degrees to the left (the direction of rotation) is where the wheel tried to pull your hand. So we can see that in addition to some of the things you already know about that are trying to run you out in the weeds, gyroscopic precession kicks in just as the tail comes up trying to finish you off. A common error is when a student gets a little squirrly on the takeoff role, he tries to cheat by getting the tail up early so he can see. He, in effect, is rushing the takeoff. Remember that once the tailwheel leaves the ground, it can no longer help you, your on rudder alone now and there might not be enough of it. What would happen here if you hadn't looked closely at the wind and had a slight tail wind?

Resist the temptation, and it is a strong one, to rush the takeoff. If things start going to hell in a hand basket early on, abort the takeoff smoothly and start over. Remember that when you chop the throttle abruptly, you taking out all of those engine induced forces that got you into trouble in the first place. Notice that I said early on. Aborting a takeoff much faster than you can run can get very interesting. Probably a good percentage of ground loops can be attributed to pilot trying to check themselves out in a tail dragger by "easing into it" or air taxiing. Don't do this! Don't try to slowly accelerate lift the tail up and then abort with the idea that you'll just quit if things start going bad. Again, torque, P Factor, and gyroscopic precession might eat your lunch. Either takeoff or don't but if you have to abort do it early. Once the tail is up, your probably better off trying to ride it out. As much as you would like to, don't rush the airplane into the air, it might come back down again and things will really get grim.

Once the tail is up, you may have a little forward visibility (depending on how big the cat in the front seat is). Pick a point on the runway or slightly off to one side AND KEEP THE NOSE STRAIGHT! If it moves a little to one side, put in a some rudder to get it back, NOW. As it starts coming back, take the input out. Don't wait for the nose to center before taking the correction out. In a nose wheel airplane, the nose wheel will track straight when it is centered because the tire absorbs the momentum of the imposed side load. You don't have a nose wheel! An object in motion will remain in motion until counteracted by an equal an opposite force. So just because the nose came back to center doesn't mean it's going to stop there. You may have to use opposite rudder to stop it. This is why when you were riding the rudders with your instructor he seemed to be doing it all backward. In reality, he was predicting where the nose would be and putting in inputs to stop it where he wanted. It's quite a dance and it takes practice. Wait till we get to crosswinds! Stop whining, you can do this and when you get it you won't want to fly anything but a tail dragger because it's more fun.

The airplane is heading off to the side of the runway and you have full rudder in and nothing is happening. That $75.00 runway light seems to have your name on it. About this time somebody yells "I've got it!" you hear a slight squeal and your headed back to the centerline, no longer a danger to women and small children. Your instructor let you go as far as he could and finally got on the brake (singular) to avoid potential disaster. Brakes can get you out of trouble but they can get you into trouble as well. When you apply brakes there is a forward pitching moment and since there is no nose wheel out there to stop you... Sufficiently strong brakes will put you on you nose! (Or eventually on your back). A calm wind takeoff should be do-able without the use of brakes. The key is stopping things before they get sticky. Remember, there is a point past which you can't get her back. Your instructor should take over before you get to that point. When he does, note where the nose was. That's about as far as you can go. Keep your gyrations inside that window and everybody's happy. We'll talk more about brakes and the takeoff when we get to everybody's demon, the crosswind.

Tug back a little on the stick and your flying at an incredibly low airspeed. That's what a Cub does, fly slow and it does it well. There should be enough air coming in through the open door to evaporate most of the sweat you've accumulated by this time so enjoy the ride. Nothing strange about this part. It is, after all "an air thang" and it is perfectly happy in the air.

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