To say the CJ-6 is unique and exotic is an understatement. On the ground, it sits high on the gear with its distinctive gull wings and it’s “turbine-esque” frontal profile. The gill shutters used for cooling the 9 cylinder, 285HP HS6A engine give the airplane a bit of a fighter jet feel – an illusion that is shattered when the throaty engine roars to life. Although “Made in China”, the CJ-6 is a high quality, well built airframe with more than fifty years of operational experience behind it. Couple that experience with excellent handling qualities in both the aerobatic and formation flight regimes, low acquisition and operating costs, and a fun factor through the roof, and it’s easy to see why the airplane is a popular “first warbird” for many pilots.
Often confused with the venerable Russian Yak-52, the CJ-6 is “not a Yak”. While it is clear that the designers went to school on Russian aircraft design, and many of the parts and pieces are interchangeable with their Russian cousins, the CJ-6 is a ground up “new design”. Systems are similar, but the design is unique.
Approaching the airplane with the intent to fly, the first thing you do is hop up onto the wing and open the canopies. A small button with just enough leverage is positioned on the forward left canopy frame. Pushing that button can sometimes be difficult, so you’ll often see Nanchang owners hold one finger on the button while gently tapping the other side of the canopy to aid in getting it unlocked. It’s not intuitive, but once learned, makes perfect sense….
Inside the cockpit the number one first job is to check that both front and rear cockpit mags are OFF. Unlike western airplanes, the mag switches are not mechanically interconnected. It’s important to check and double check both front and rear mag switches.
With the mags off, this is a good time to check the oil. The dipstick is located forward of the canopy, and some gymnastics will allow you to access it and check the oil. 11 liters (this is a Chinese airplane) is the minimum for flight.
With oil checked and mags off, it’s time to preflight the rest of the airplane. In most respects, preflight is no different than any other aircraft, but there are a couple critical items to pay special attention to.
Because it is a radial, and because the engine sits vertically (unlike a taildragger), the airplane is especially prone to hydraulic lock. The oil tank sits above the engine, so oil is always trying to flow down to the lowest point, which is the lower cylinders. Even with check valves installed, if the airplane sits long enough oil will flow.
The way to prevent hydraulic lock is to check for it before you start the engine. You do this by pulling the propellor through 12 blades. If there is oil in one of the lower cylinders, that oil will make it extremely difficult to pull the prop through by hand. If you find yourself needing more than a firm pull to get the prop to move, it’s likely you have oil in a cylinder. Don’t force it!
The trick to clearing hydraulic lock is to get the oil out of the cylinder. With both valves closed and the piston on the way up to top dead center, there really isn’t a way to do this without pulling a spark plug. You could pull the prop through backwards, looking to open the intake valve, but in most cases this isn’t a good idea. All you are doing is dumping oil into the intake tube, where it has nowhere to go. You’ll be able to pull the prop through and think you are good to go, but in reality you have a whole bunch of oil waiting to be sucked into the cylinder. At idle, there may not be enough vacuum to pull it in, but when you go to full power, you might get a big slug of oil in the cylinder at exactly the wrong time, and this will almost certainly damage the engine or worse.
There is an exception, however, to the “don’t pull the prop backward” rule, and it applies to this airplane. If you have intake drains installed, one strategy is to open them and then let the oil that enters them drain before starting. This also prevents oil that may have entered the intake from the cylinder through an open intake valve from collecting in the intake as well. If you have oil in the cylinder, it will either exit through the exhaust while pulling prop forward, or through the intake drain if you go backward.
If you suspect oil drained into the intake, it’s a good idea to be patient. The drains are not big, and oil can be thick. Plan to wait a few minutes before starting if you think you have oil there. One trick is to use the primer to dilute the oil. The important fact is, you want to make sure oil is clear of both your lower cylinders and your intakes before starting the engine.
Once we’ve pulled the prop through and waited for any excess oil to exit the intake drains, we close the drain and continue with our otherwise normal preflight. Once we’re satisfied the airplane will fly, it’s time to jump in the cockpit!
Starting this airplane is relatively easy. The starter is pneumatic, so you’ll need air pressure to turn the prop. The start procedure is switches on (master, engine, gear, ignition), pump up fuel pressure with the hand pump, add a few shots of prime, open the air tank, turn on the mags (front and back) and press the start button.
The start button energizes a “shower of sparks” that helps to get the engine running. After a few blades the engine will cough to life. Rarely it requires a shot of prime to keep it running, but most starts are easy two or three blade affairs. With the engine running and idling at 1000 RPM, you switch on the radios and you are ready to go.
Taxiing the CJ-6 can be a bit of a challenge to the uninitiated. The nosewheel is castering, not steerable, and you use differential braking to steer. All standard stuff, but the brakes are activated differentially with a hand brake on the stick. The position of the rudder pedals controls which brakes receive air, and you modulate with the hand brake. This can be a bit confusing the first time out, and new CJ-6 pilots often do a 360 or two before getting the hang of it, but once learned it’s intuitive and straight-forward.
Takeoffs are easy. You won’t notice that you are using left rudder instead of right rudder. That will come naturally. The airplane accelerates easily and flies smoothly off the ground. The gear is raised pneumatically with a noticeable “whoosh” that can surprise the uninitiated. After takeoff, throttle back to 700mm and 2250 RPM for a decent climb even on a hot day.
The airplane flies honestly. Aerobatics are easy, with most “sportsman” maneuvers easy to accomplish. There is no inverted fuel or oil, so best to keep things positive. The airplane will snap, but honestly it’s not really designed for that mission. Loops, rolls, hammerheads, and spins are all in the repertoire. The airplane stalls honestly both clean and dirty, and will recover from most spins hands off (although proper technique is always appreciated). It is a great formation airplane, capable of flying with most of the popular partners (T-34’s, T-6’s and other CJ-6s).
Cylinder head temperature management is important – controlled by gill shutters on the nose actuated by a knob in the cockpit. Constant monitoring is important to ensure you keep them both warm enough and cool enough.
In the pattern the airplane is also honest, but with the big flap hanging down it can exhibit quite a startling sink rate. Do not expect to glide very far with the gear and flaps hanging down. The trailing link landing gear makes an average landing great, and the airplane tracks well on the ground once the mains are down.