The USAAC sent bids for such an aircraft to multiple manufacturers. The ensuing competition ultimately came down to three, each building three prototypes in 1939 for the contract. Bellanca responded with the YO-50, a high-wing taildragger with an enclosed tandem cabin powered by a 420-horsepower Ranger inverted V-12. Stinson responded with their L-1 Vigilant, an aircraft of similar design but with a more traditional 295-horsepower Lycoming radial engine.

Ryan’s offering was the YO-51 with a company name of “Dragonfly,” and it incorporated a few unique features that made it stand out from the other two contenders. Rather than being equipped with an enclosed and glazed cabin, the Ryan utilized an open cockpit beneath a parasol wing. While doing away with a cabin altogether makes for an effective observation platform by eliminating a number of blind spots, one wonders how effective the airplane would be in frigid northern climates with cold and fatigued crew members.

The Ryan’s landing gear was quite different from the others but nearly identical in design to the Storch. While the YO-51 differed by integrating the wing strut into the design, both the Ryan and the Storch utilized an extremely wide stance and long-travel suspension. In the case of the Storch, it provided a plush 16 to 18 inches of suspension travel to soak up all but the most violent landings. 

In addition to being a parasol design, the Ryan’s wing incorporated full-span leading-edge devices. Publications differ in their description of them, randomly referring to them as slots, which remain fixed in position, and slats, which move between retracted and extended positions in flight. The publications can perhaps be forgiven, however, as photos exist showing both variants installed on different YO-51s.

Ryan chose full-span Fowler flaps for the trailing edge, a then-revolutionary design utilized by Lockheed on the 14 Super Electra and later on most high-wing Cessna models. Notable for introducing primarily lift in the first segment of travel and then drag at higher settings, these flaps helped to enable exceptional STOL performance, particularly when they make up the entire trailing edge of the wing. To provide roll authority in the absence of traditional ailerons, Ryan equipped the YO-51 with roll-control spoilers.

To the delight of U.S. Army Air Forces (USAAF) maintenance technicians, Ryan eschewed inverted V engines and instead opted to use a common and known engine, the Pratt & Whitney R-985 Wasp Junior radial. Producing 440 horsepower for the YO-51, this engine was also utilized in the Beech 17 and 18 as well as the de Havilland Beaver and Vultee BT-13 Valiant. With almost 40,000 built over the years, Ryan must have touted their engine choice as far more sensible than Bellanca’s.

The three YO-51s, wearing serial numbers 40-703, 40-704, and 40-705, first flew in 1940 and predicted performance was achieved in flight testing. Hard data is sparse, but multiple sources report the 4,200-pound airplane could take off in less than 100 feet and clear a 50-foot obstacle in slightly less than 500 feet. Landing over a 50-foot obstacle reportedly required 400 feet. 

When it came to speed, the complex wing enabled a broad operating range. Stall speed was reportedly only 30 mph, while cruise speed was a healthy 107 mph. These numbers were nearly identical to the Storch…and, perhaps not coincidentally, also nearly identical to the Bellanca and Stinson with which it was competing. 

During some of the first test flights, spectators were wowed by the performance. An article in a Ryan company newsletter reported that during one takeoff, the YO-51 “leaped into the air after a run of only 50 feet, pointed its nose at a 60-degree angle, rose almost vertically and remained virtually motionless over the airport.”

The March 15, 1940, edition of the Air Corps Newsletter described the YO-51’s flight capabilities in an even more colorful manner, observing, “The first model of the YO-51 has been grasshoppering in our midst and is doing things that have reduced our carefully nurtured conceptions of how an airplane flies to a pile of ashes.”

Despite such impressive grasshoppering, the USAAC competition was ultimately awarded to Stinson. During its production run, some 324 examples of the O-49 (later L-1) were built for the U.S. and the Royal Air Force.

Sadly, no trace of the three YO-51s nor the three Bellanca YO-50s remains today. One account reports that the three YO-51s were utilized as “ground instructional airframes,” and it’s likely that all six contenders were ultimately scrapped at some point thereafter. 

The post The Ryan YO-51 Wowed with STOL Performance appeared first on FLYING Magazine.

Like grand-touring automobiles, these personal jets have targeted the well-to-do traveler, intent on covering sizable distances with a companion and some luggage. At the same time, manufacturers hedged their bets by touting the category’s suitability for limited military roles, such as training and utility duties.

Few mini-jets ever reached series production. French manufacturer Morane-Saulnier saw some success with its MS.760 Paris jet in the 1960s. More recently, Eclipse Aviation flew its Concept Jet prototype but, like most other modern efforts, ultimately settled on a larger six-place design.

Polish manufacturer Flaris appears to be the only company with the potential to buck the trend and bring its contender to production. Naming it the LAR 01, Flaris introduced the small, 4,079-pound (maximum takeoff weight), single-engine jet in 2013 and conducted the first flight in early 2019. While it technically has five seats, it is perhaps more accurately described as a four-plus-one, as, like a sports sedan, the fifth seat is nestled between the two back-seat passengers.

The overall airframe layout is logical. The single Williams FJ33-5 engine needs to be placed on centerline, and to avoid robbing internal volume with the engine and ducting, Flaris followed the lead of Eclipse and Cirrus with a dorsal engine pod. To separate the LAR 01’s tail surfaces from hot engine exhaust, Flaris opted for a “U-tail” with two small vertical stabilizers at each tip performing yaw duties. 

Whereas the overall airframe layout is predictable, the execution is intriguing. Flowing lines define the fuselage, from a constant arc along the belly to the organic window and door shapes up front. Faced with the decision to retract the main gear into the wing or the lower aft fuselage, Flaris opted for the latter, enabling a thin, efficient wing design.

Flaris touts an 18-to-1 glide ratio, besting the 14.7-to-1 ratio of the Cirrus Vision Jet and actually matching that of early Schweizer gliders. This abundance of aerodynamic efficiency also provides healthy returns during takeoff and landing. The LAR 01 requires just 656 feet to take off and 820 feet to land. Interestingly, Flaris has designed and approved the jet for operation from grass fields, a feature not commonly seen among jet-powered aircraft that aren’t built by Pilatus.

The stall speed of the LAR 01 is a meager 62 knots, enabling the pilot to dissipate a significant amount of energy prior to touchdown in the event of a forced landing. Alternatively, they can deploy the parachute as in the Cirrus.

Rather than utilizing a traditional thrust lever mounted atop a center console, Flaris has installed a single control stick in that position, with dual thrust levers mounted on both outside edges of the glareshield. Accordingly, each front-seat passenger would use their inside arm to control the jet and their outside arm to actuate their thrust lever.

To date, only one LAR 01 has been built, and it appears to be progressing through flight testing. However, a second airframe has been completed as an unmanned aircraft and was displayed at the 2023 Dubai Airshow following a United Arab Emirates defense firm purchasing a 50 percent stake in Flaris. Whether that deal will affect the development and certification of the LAR 01 remains to be seen.

The post Flaris LAR 01 Still Has Potential appeared first on FLYING Magazine.

The cost to train pilots in advanced jet trainers, therefore, was following suit. One company in Germany spotted an opportunity for a more cost-effective alternative. If it could design an advanced trainer that was drastically less expensive to operate, it reasoned it would be of interest to militaries around the world.

The company was Rhein Flugzeugbau (RFB), and by starting with a clean-slate design, it proposed an entirely new aircraft called the Fantrainer. It would utilize a ducted fan nested within the empennage, and the forward section and cockpit would closely resemble operational jet fighters. By driving the ducted fan with one small turboshaft engine, fuel consumption would be dramatically reduced compared to pure jets. When combined with an airframe optimized for training and low manufacturing cost, RFB was confident the aircraft would sell well.

Developing a cost-effective advanced trainer wasn’t a new concept. Other manufacturers had pursued the military trainer market with single-engine turboprops, such as the Pilatus PC-7 and Beechcraft T-34C Turbo-Mentor. These had secured many military contracts, but the traditional propeller configuration provided handling and flight characteristics quite unlike the jets for which they were preparing their pilots. By integrating the ducted fan within the aft section of fuselage, RFB successfully eliminated virtually all of the left-turning tendencies of a single-engine turboprop and offered an advanced trainer with handling that was a much closer approximation to tactical jets.

The secret was in the shroud. Larger, conventional propellers come with distinct limitations— propeller efficiency drops off dramatically beyond a certain rpm, for example, limiting the maximum allowable rpm. By utilizing a small fan under 4 feet in diameter, it could be turned at a higher rpm, and the shroud can act as winglets do on wingtips, increasing efficiency even further. Additionally, sufficient propeller clearance requires longer, heavier landing gear, so the small fan permitted a more compact gear design.

For these benefits to be realized, however, tip clearances have to be tiny—in the case of the Fantrainer, about 2 millimeters—and this requires an extremely stiff structure. To achieve this, RFB designed the empennage around thin vertical and horizontal sections joined by the circular shroud. FLYING’s Peter Garrison wasn’t impressed, observing, “It would be difficult to imagine a less promising structural arrangement. Its numerous surfaces and intersections threaten to multiply sources of drag, while its peculiar load paths and concentrations do the same to weight.”

Performance was, therefore, underwhelming. RFB would ultimately manufacture two versions of the Fantrainer, and the more powerful 650 hp version would only achieve a 225-knot maximum speed—barely more than the aforementioned turboprop trainers, each with 100 less horsepower. And while the Fantrainer did indeed mimic the handling and feel of a jet, it came at the cost of unique, proprietary parts and systems that would introduce complexity to maintaining a fleet.

Accordingly, only 50 examples were built. These were delivered to the Luftwaffe and Royal Thai Air Force. In an attempt to expand and diversify its offerings, RFB teamed up with Grumman American to market the Fanliner, a futuristic two-seat light aircraft that paired a smaller ducted fan with a 114 hp twin-rotor Wankel rotary engine. Only two examples would be built.

Despite the limited sales, however, there remains a sliver of hope for the Fantrainer. In 2010,  German company FanJet Aviation GmbH bought the certification and tooling and is presently marketing it for military and civil training purposes. Unfortunately, the last news update on the company’s website was posted in July 2022, and no production orders appear to be forthcoming.

The post The RFB Fantrainer Turboprop Was Meant to Handle Like a Jet appeared first on FLYING Magazine.

After coming to terms with the lowly assignment, some closer investigation would have likely cheered you up. The aircraft would be called the Model 48 Charger, which would be Convair’s entry into a competition against eight other manufacturers. Each would create a clean-sheet aircraft proposal to fulfill a contract in which the U.S. Army, Marine Corps, and Navy would ultimately be involved.

The Charger would be required to take off from an aircraft carrier without catapult assistance. It would also be required to operate on floats and from unimproved runways while carrying six troops in addition to the pilot. It was a unique blend of technical requirements. While the project perhaps lacked the prestige of the company’s supersonic offerings, it presented some challenges that must have been intriguing to every engineer assigned to it.

Compared with the proposals from companies like Grumman, Beechcraft, and North American, the Charger stood out with a shockingly stubby wing. While the aircraft itself was not diminutive, with a maximum takeoff weight of more than 10,000 pounds and two 650 hp Pratt & Whitney PT6 turboprops, the King Air-sized machine sported a wingspan only 3 feet greater than that of the 1,100-pound Grumman AA-1. Even after a wing extension early in the test program, the wingspan remained 3 feet less than a Cessna 150.

The secret was prop wash. The wing was designed in such a way that nearly all of it was blanketed in the prop wash from each engine. Because the local wind velocity enveloping the airfoil was therefore accelerated, the wing was able to produce lift at lower indicated airspeeds. Bolstering this performance were flaps that were as long as the wing and extended to an extreme 90 degrees for landing. Inboard Kruger flaps, not unlike those on the Boeing 727, adorned the leading edge.

This resulted in shockingly impressive takeoff and landing performance. Janes’ All the World’s Aircraft lists the Charger’s takeoff and landing distances as each being less than 500 feet. Even more impressively, this is listed as the distance required to clear a 50-foot obstacle. While no conditions or parameters were listed, the numbers are impressive, even if little to no payload was necessary to achieve them.

Depending on engine thrust to maintain so much of the wing’s lift was clearly effective. But like a blown wing, an abrupt loss of engine thrust below a certain airspeed would result in a stall. Should just one engine or propeller fail at a low airspeed, an irrecoverable loss of control could occur.

The final product resembled a clipped-wing OV-10 Bronco, with a twin-boom tail, long-travel landing gear, and a canopy that offered nearly unlimited visibility. Like the Bronco, the tail cone could be opened to reveal a small cargo area. This area was proposed to be used for troops and stretchers.

Intended to fulfill various roles, the Charger was also equipped with ordinance. Four machine guns and five hardpoints could be used for counterinsurgency (COIN) missions. Drop tanks could also be fitted to provide a 2,600 nm ferry range.

Although Convair hustled to take the Charger from paper to first flight in only 40 weeks, the company’s efforts would be for naught. In October 1965, while on its 196th test flight in San Diego,, a test pilot crashed the lone prototype, sustaining serious injuries and damaging the aircraft beyond repair. The exceedingly sparse National Transportation Safety Board report stated that the “military test pilot used improper [engine] shutdown procedures [that] caused [generator] reduction gear pinions [to] seize.”

The report indicates an engine failure occurred, and under “Phase of Operation,” it lists two phases—normal cruise and go-around. Assuming the initial engine failure occurred during cruise and the accident occurred during a go-around, the unconventional engineering that enabled the Charger’s outstanding performance might have contributed to its demise.

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