• J.K. Caldwell

Ryan PT-21/22 "Recruit"

Updated: Dec 28, 2021


Ryan PT-21_22
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First Impressions: This monoplane with Art Deco lines gives the feel of a 1930s sci-fi rocket. It is impossible to fly this machine without feeling the thrill of adventure! And the sound…few engines are as distinct as the irregular popping of the Kinner 5- cylinder radial.

Background: The Ryan Aeronautical Company originated in San Diego in 1934 and began production of the Ryan ST (Sport Trainer). Subsequent variants of the ST included aerobatic and supercharged variants of the Menasco 4 cylinder, inverted in-line, air-cooled engine. In 1937, Ryan developed the ST-M in response to the Army Air Corps’ request for some modifications to suit their military requirements. The end result was the PT-22. The modifications included wider cockpits to allow seat parachutes, exterior fuselage reinforcement stringers, a roll-over post on top of the fuselage, the removal of wheel pants, a wider landing gear stance, hydraulic brakes and, of course, a radial engine. Legend has it that none other than Chief of the Army Air Corps, Hap Arnold himself, said the new Ryan trainer will have a radial! Because of these modifications and gross weight increase, the design engineers created a wing sweep of 4 degrees for CG considerations. The end result was the Ryan Aeronautical Company’s manufacture of 1,023 PT-22s with about 225 PT-20/21 and NR-3 (U.S Navy variant) trainers. Although not as prolific as the Boeing Stearman PT-17, the PT-22 trained thousands of U.S. Army Air Corps pilots from 1941-1945, mostly in Visalia, CA. After the war, many PT-21s and PT22s were redesignated as ST-3KR (Kinner Radial).

Fuselage bulkhead in the front cockpit

Design Features: The Ryan can be described as a biplane without the second wing. In other words, it uses the same principles of load and lift distributions as a biplane. The wings are attached with a hinge point about 18 inches from the fuselage and use streamline flying wires connected to the landing gear struts and landing wires attached to the fuselage. If the Kinner engine is the heart of the PT-22, the bulkhead, located in the front cockpit, is the backbone. This oval bulkhead looks more like it should be on a battleship than in an airplane. The bulkhead has gigantic 1/4 inch rivets. Almost everything structural on the Ryan connects at this bulkhead, including the bracing wires, wing roots and landing gear. The engineers built this trainer to withstand abuse from students which a careful look at the construction will prove. Fuselage bulkhead in the front cockpit.


Powerplant: PT-22s were fitted with variants of the Kinner R-55 or R-56 fivecylinder radial that turns a Sensenich or Fahlin wood propeller. Three of the four cylinders have a short-stack exhaust while the other two (10 and 12 o’clock position) are shrouded. The carb-heat muffler serves two purposes; it keeps exhaust fumes from being blown in the pilots’ faces and provides carburetor heat. The engine uses a dry oil sump with a separate oil tank. Most modern owners incorporate some type of shutoff valve to keep from dumping a considerable amount of oil after the flight.


Preflight: Check standard airframe structural integrity and pay attention to all flying and landing wires, as well as the bracing and struts. And yes, there are a lot of them! Of note, a quick way to determine the difference between a PT-21 and PT-22 is that the curved aileron counterweight is on the bottom of a PT-21 and the top on a PT-22. Apparently the U.S. Army Air Corps soon discovered that the bottom side counterweights were frequently ripped off during a ground loop. Preflight typically includes collecting oil that has drained out of the two bottom cylinders (about 1 quart) since the last flight and pouring it back into to the oil reservoir in the fuselage immediately behind the engine and forward of the fuel tank. After ensuring that the magnetos are cold, turn the propellor through 5 times to check for hydraulic lock. Immediately behind the engine on the left side of the fuselage, turn the oil sump valve on (if so equipped) and prime the cylinders with two shots of fuel (also if so equipped). Make sure the parking brake is set, the mixture is rich, and then give the throttle four shots forward to let the accelerator pump shoot fuel into the intake manifold. With the throttle at idle, carefully hand prop the engine through. A slight flick of the prop will kick over the magneto impulse coupling. When it catches, you’ll be rewarded with the “chickety chickety” sound of a Kinner at about 600 rpm. Step on the wing, grab the horsehair-stuffed leather padding around the cockpit, and climb in. Strap in carefully - It’s an open cockpit after all! Buckle your leather helmet, disengage the parking brake and taxi out, S-turning gently to catch glimpses of what’s in front of you. Run-up is done at 1,200 rpm. Only the mags, carb heat and engine instruments need to be checked. Set trim for takeoff and ensure the flaps are up.


Takeoff: Line up on the runway and slowly push the throttle all the way forward and feel the blistering acceleration (not really). To prepare yourself, you must recognize that max rpm of the Kinner is only slightly over 1850 rpm, only achievable in a dive. Takeoff rpm will be around 1600 rpm, much less than most pilots are used to, which is why more than a few have ground-aborted, assuming something was wrong. Once the aircraft has a few knots of airspeed, you can push the tail up slightly, placing the lower rocker boxes of the 10 and 2 o’clock cylinders on the horizon. When the Ryan is ready to fly, it’ll gently part ways with the earth. A climb at 85 mph will yield 600-700 fpm climb on only the very best of days.


Flight Characteristics: It is said that everything in a Recruit occurs at 90 mph and that’s not far off. Not much right rudder is required in the climb probably, in part, due to the low rpm. The cockpit seems to be less windy than a Stearman and view is much better; unhindered by an upper wing. Because the fixed vertical stabilizer is so small as compared to the rudder, constant rudder pressure is required throughout flight, probably only noticeable on long straight-and-level flights. The PT-21 I flew stalled at about 64 mph with approximately 30 degrees of flaps and, even with the ball in the middle, it had a tendency to drop off, due to the 4 degrees, 10 minutes of wing sweep. The wing drop is not alarming; it just requires a release of back-stick pressure and opposite rudder. The PT-22 has the reputation of being a “killer” because of the number of fatalities caused by the stall/spin. There is nothing remarkably deadly about the stall characteristics, but they do require more understanding and proficiency than the other primary trainers of WWII: the Fairchild PT-19/23/26 and the Boeing Stearman PT-17, whose gentle characteristics were well-suited to taking young men straight from the farm into the cockpit. That being said, the PT-22, with higher landing speed and flaps, better prepared student aviators for the higher performance airplanes they’d be flying later in training. Also, this plane is a blast to snap-roll!


Landing: Pull the carb heat lever on and decelerate below flap speed. The flap handle is by the pilot’s left hip in both the front and rear seats. The flaps are mechanically operated and use a pawl to engage a rack gear. The cockpit lever is pushed down and the up actuation brings the flaps down. Five actuations will bring the flaps completely down, which lowers the stall speed by only 2 mph! To raise the flaps, the flap handle is pushed further down and will immediately brings all flaps up. It’s important not to accidentally bump the handle while close to the ground with flaps in. If you do, they will immediately retract. One recommended approach is to turn base to final at approximately 800’ agl and pull the throttle to idle, using a forward-slip to maintain a view of the landing area until just before the flare. The Ryan sinks like a rock; even more than a Stearman, but then again, it only has half the wings! As the slip is taken out, it would be prudent to add a bump of power to reduce the rate of descent as you transition to the landing flare. The Treadle-type oleo landing gear can be described as “leading-link landing gear”. Because the landing gear is connected at the main fuselage bulkhead and coincident with the CG, leading-link landing gear is necessary to place the wheels forward of the CG. The design is fantastic for absorbing almost any poor landing without a bounce, and there are no issues with either a three-point or wheel landing. There is nothing abnormal about the amount of rudder input, and you can use the toe brakes when slow enough. Realize that once the tail is lowered, you lose sight of the runway in front of you until you’re slow enough to start the S-turning again.


Wrap-up: If you are a warbird or antique airplane buff, this should be on your bucket list. This airplane appeals to all the senses; its sleek lines, forward-bent landing gear, bracing wires, and the unique sounds that emanate from the Kinner radial engine will definitely grab anyone’s attention. You’ll smell the countryside, and if you lean your head out the cockpit with mouth open, you might even taste a bug! Don your leather helmet, goggles, and silk scarf and jump in this gorgeous machine from a by-gone era!

It was Monarch butterfly migrating season in Texas!



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