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Piper Cub & the Reed Clipped Wing Conversion

Piper Cub & the Reed Clipped Wing Conversion Featured

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In the early 1930s, businessman William T. Piper became involved with the Taylor Aircraft Company. C.G. Taylor designed a light aircraft with steel framework, tubular struts, rubber shock cord landing gear and wood wings with spruce spars.

The first production Cub, called the E-2, was soon flying with an A-40 Continental engine of nearly 40 hp. With a gross weight of 925 pounds, it took off in a few hundred feet and flew at nearly 75 miles per hour. The flyaway price was $1,325, and it was licensed by the Department of Commerce in 1931.

The ubiquitous J-3 appeared in 1937 sporting an improved 115 cubic inch A-40 with the full 40 hp, a balanced rudder, more instruments, and an aluminum sleeve around the exhaust stack to provide some heat for the cabin and carburetor. Brakes and a steerable tailwheel soon appeared, as did the familiar Cub Yellow paint with black trim.
In the late 1930s, engines were being improved; new designs from Franklin and Lycoming were providing from 40 to 50 hp. By 1939, all three engine manufacturers were producing 65 hp engines. The stock Cub as we usually see it today includes this larger engine.

Clipped Wings
The Reed Clipped Wing version of the J-3 was flown as an airshow mount by many of the performers of the 1950s. In this modification, about 40 inches are removed—not from the tips, but from the roots of each wing—in accordance with the Reed Aircraft Modification Manual. This modification allows operation in the FAA Standard Category.

This Cub version is smaller in span, with the original ailerons reaching nearly to the fuselage, giving a remarkable increase in roll rate and authority. The smaller aft lift strut is replaced with a larger-sized and stronger front strut.

Often the engine horsepower is increased for additional performance. Our Clipped Cub sports an 85 hp Continental engine, giving it a noticeable 30 percent increase; it’s a nice boost.

Preflight
Let’s preflight and fly this true legend of sport aviation. Our walkaround inspection starts with a look inside at this simple, functional airplane. The magneto switch, on the left side above the sliding window, is off initially. The fuel valve on the left side is turned on. The engine is in plain view with four jugs sticking out for our inspection. The oil dipstick is on the right side of the Continental and reads full with four quarts.

The fat 8.00 x 4 tires are inflated to 12 psi. The Piper service manual cautions that operation when the tires are soft may cause creep with consequent damage to the valve stem. A new tube costs about $100.

Getting In
Entering the Cub requires some planning. The tandem-seat Cub is soloed from the back seat only. If you are of moderate height, you may place your left foot inside on the floor and using the diagonal heavy tube overhead, just lift yourself in. A shorter pilot may use the step below the door. No feet on the lift struts, please.

Getting into the front seat is a little more difficult. One entry method requires sitting on the door sill, putting your right foot on the tire, and using the overhead tubes to lift yourself in. The front seat is the smaller of the two and may seem a little cramped for the average-sized pilot.

Cub 1 web

Starting Up
Now it is time for engine start. The process is switch on, brakes set and throttle cracked. If the engine has been run recently or was primed, one pull of the prop will start it.

The backseat view is somewhat limited until the tail is raised, so stretch your neck to have a good look forward before you taxi. Performing S-turns will keep you clear while en route to the takeoff runway.

Our J-3 has the original heel brakes—and Cubs have really poor brakes, but the gentle nature of this trainer makes taxi maneuvering a piece of cake. Solo is from the back seat for proper center of gravity. If it is windy, use the effective flight controls for proper wind correction and you will easily keep the aircraft under positive control.

After the brief pre-takeoff check, taxi into position and let the airplane roll forward slightly to align the tailwheel. Now move the stick back for good tailwheel response, smoothly add power… and in 300 to 400 feet, we are airborne.

The Reed Clipped Wing version is limited to 1,100 pounds maximum takeoff weight. Normal J-3s are allowed 1,220 pounds; our lighter-weight airplane accelerates faster and gets off Troy Airpark’s (02MO) smooth turf strip in short order.

You will see climb rates from 500 to 1,000 feet per minute at 55 to 60 mph depending on total weight and ambient temperature. Of Earl Reed’s list of a dozen modification advantages, the increased roll rate and increased strength made ours a very popular Cub model.

Orientation
We are soon up to a suitable altitude for the beginning of our orientation, which means slow flight and stalls are in order. We find the carburetor heat control on the right side of the cockpit and pull it back to the “on” position and then reduce the power.

Airspeed is soon down to the 50s and we find that the Clipped Wing Cub handles very responsively at 50 to 60 with no unusual flight characteristics.

Add power, resume normal speed, do clearing turns and let’s look at a power-off stall: Nose up, 15 to 20 degrees above the horizon; carburetor heat on; power off—and hold that altitude until we see the indication of a stall. The nose drops gently; the rudder has good authority (which we will appreciate later during hammerhead turns).

The stalls and slow flight maneuvers show that the short wing modification does not detract from the Cub. In fact, it still has the flight characteristics of an excellent trainer airplane.

It is time to climb higher for some fun flying: basic acro. The short 28-foot span and original ailerons—now nearly full span—give the aircraft a fairly fast roll rate. It is not a Pitts roll rate; however, I would estimate roll rate slightly better than a Citabria or Decathlon.

Cup goingdown web

Basic Maneuvers
Let’s do the basic aileron roll. Clear the area, add some power, lower the nose and accelerate to at least 100 mph. Pitch the nose up to 20 degrees (which will prevent excess altitude loss) and neutralize the stick. Full aileron is then easily applied; hold full aileron.

These control inputs must be done quickly—since the nose is up, speed will decay. Slight forward stick while inverted will keep the nose up. As you roll to level flight, neutralize the ailerons and pull up to normal flight.

The loop is next on our list of basic maneuvers. To loop the Clipped Wing Cub you need about 110 mph, and + 3.5 G will give you the pull-up for a nice round circle. Depending on the horsepower of the engine installed, a slight dive is generally needed to attain the entry speed. The rear seat flying position of the Cub is good for observing the wing trailing edge with relation to the horizon, to keep the circular pattern vertical for the maneuver.

Establish straight and level with the ball centered and bring the stick firmly back while looking forward. As the nose rises above the horizon, apply full throttle and keep the wings level with ailerons and the circular path vertical with the rudder.

As the horizon drops out of sight over the nose, the wings are checked against the horizon. Nearing inverted, the stick pressure is reduced slightly to keep the loop round. Notice the decreased pressure on the seat as the G load is decreased.

As we become inverted, we reduce the back pressure more, and as we start down the backside of the loop, airspeed and rpm will increase—so decrease the throttle and look back through the skylight for the horizon coming into view.

Remember that as we increase power at the beginning, we need right rudder to compensate for engine torque and P-factor. When we later reduce power, take out that right rudder. As speed increases going downward, opposite rudder will be required. We must now start increasing back pressure on the stick to keep the loop round and prevent excessive speed on the return to straight and level.

For the hammerhead turn, line up over a straight road, put the nose down in the now familiar shallow dive and get a least 100 mph. Pull the airplane up smoothly to the vertical while applying full throttle. Maintain the horizon reference out the side windows. You may need a little forward stick to keep the aircraft vertical.

Check your airspeed, as it is dropping rather rapidly. At 50, apply hard left rudder and keep alignment by using your outside reference road. Controls are immediately effective. Start the rudder back to neutral as the nose passes through the horizon. As you begin the vertical dive, ease off the throttle, and at 70 to 80 smoothly apply back pressure to start the nose up. Add power to terminate the maneuver in level flight at about 100 mph.

Landing
Landings are just plain fun in this docile and gentle aircraft. The regular Cub stalls at under 40 and the Clipped Wing version stalls at just over 40, so use an approach speed of 60 mph.

If you have been flying a regular Cub you will notice a big difference in the sink rate on the final approach in this aircraft. With almost 7 feet less wingspan and about 40 square feet less area, the Clipped Cub has a more positive descent rate.

A little power will make the approach easy to control on the desired angle and will allow you to put it right on the spot. The higher wing loading also lets you handle higher wind conditions. In ground effect the clipped Cub lets you round out and make those “kiss the grass” landings that will stroke your ego.

The Clipped Wing version of the Cub is an excellent trainer because it is responsive, crisp on the controls and has a better power-to-weight ratio. Having trained students in small and large aircraft, I appreciate an aircraft that responds nimbly when you need to recover from a student’s less-than-perfectly-executed maneuver.

Frank Baldwin, ATP, CFII, A&P is a retired airline pilot and enjoys flight instructing in taildraggers, gliders and twins. He spends his free time developing Troy Airpark, a sport aviation community near St. Louis—and flying his other joy, the Pitts.

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Last modified on Thursday, 14 July 2016 00:54

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