The XR-1 was the first American military helicopter to takeoff and hover with good control. The work of German aircraft designer Henrich Focke inspired two American engineers, W. Laurence LePage and Havilland H. Platt, to design the XR-1. Focke's Focke-Wulf Fw 61 helicopter employed a pair of main rotors turning atop pylons, or outriggers, jutting away from both sides of a central fuselage. During the late 1930s, the Fw 61 was flown to set a number of helicopter world records. In February 1938, W. Laurence LePage witnessed the Nazi test pilot, Hanna Reitsch, fly the Fw 61 in front of several thousand people inside a Berlin sports arena called the Deutschlandhalle. Platt tried to negotiate with Focke to purchase the rights to build the Fw 61 under license but the German engineer insisted on too many restrictions and no agreement was reached.

Third Reich propagandists seized on the Fw 61 as a demonstration of Nazi technical prowess. Newsreel footage of the Deutschlandhalle flight circulated around the world, demonstrating to many that the helicopter was not only technically feasible, but that fascist Germany was leading the way in developing it. Other designers tried to duplicate Focke's success. In England, James Weir constructed two aircraft based on Focke's design principles, but neither aircraft flew as well as the Fw 61. Russian efforts to duplicate Focke's designs also failed.

Before teaming with Platt, LePage worked as an engineer on various autogiro projects for the Pitcairn Autogiro Company and the Kellett Aircraft Corporation. This experience was important because many of the critical design features necessary to build a practical helicopter were first developed and tested on the autogiro. Platt was a mechanical engineer who helped develop the automotive automatic transmission. He was also an outspoken advocate for vertical flight aircraft. At the end of 1938, the two men formed a company to design an improved variation of the Foche-Wulf Fw 61.

Month by month, the likelihood for world conflict grew and the U. S. Army Air Forces (AAF) began funding efforts to recover some of the ground lost to Germany in arms development. LePage had impressed U. S. government engineers with his film footage of Focke's achievements and he hoped this might spur federal investment in his helicopter projects. His efforts did gain the attention of AAF planners and members of the Congress. Pennsylvania congressman, Frank Dorsey, passed a bill in 1938 supporting helicopter research and development. The initial amount provided by the bill was $2 million dollars and it jump-started the American helicopter industry. Le Page may well have influenced Dorsey to pass this important piece of legislation.

When the U. S. Army Material Division published the first specifications for an AAF helicopter on August 25, 1939, Platt and LePage had already made considerable progress on several helicopter designs. In less than a year, they formed the Platt-LePage Aircraft Company and they completed more than half the design and construction of their first helicopter, the PL-3. The AAF helicopter evaluation board met on May 27, 1940, to review bids to build "a rotary wing aircraft in the interest of adequate national defense." A design based on the much-publicized Fw 61 held a clear advantage. Platt-LePage was chosen and accepted a government contract worth nearly $500,000 on July 10, 1940, to produce the PL-3 under the AAF designation XR-1.

Platt and LePage designed the XR-1 with a fuselage containing a two-place, tandem cockpit covered with sliding canopies. The pilot flew from the front seat and the observer sat behind him. The empennage consisted of a "T" stabilizer arrangement similar to the one utilized on the Fw 61. A Pratt & Whitney R-985-23 radial engine producing 440 horsepower was mounted behind the cockpit in the center of the fuselage. The rotors were mounted at the end of wing-like pylons that extended laterally and with some dihedral from the center of the fuselage. The cantilever wing pylons were designed to develop some lift in forward flight and reduce the disk loading (aircraft flying weight) bearing on the rotors. Landing gear consisted of two fixed main wheels on oleo struts extending from the rotor pylons and one tail wheel. All wheels could castor freely to ease ground handling. One problem addressed early in the design was downward visibility during vertical landings. The solution adopted then and still used today was to cover the lower nose section in Plexiglas.

Platt-LePage's XR-1 took to the air, restrained by a safety tether, on May 12, 1941. The first flight without a tether took place on June 23. From the outset several problems were evident. The aircraft was difficult to control and suffered from excessive vibration. One daunting problem was the automatic, collective pitch control system, which could cause control reversal, especially during turns. These control irregularities caused the company test pilot, Lou Leavitt, much concern and slowed the pace of flight-testing to a crawl.

Among the Platt-LePage engineering staff working on the control problem was a young engineer named Frank Piasecki. Piasecki later resigned from Platt-LePage and started his own successful helicopter enterprise. He built a rotorcraft called the PV-2 (see NASM collection) and flew it to earn the first U. S. civil helicopter license ever issued.

Control problems continued to hamper the XR-1 long after Piasecki departed. Platt and LePage were better managers than engineers and this greatly hampered efforts to improve the helicopter. But the middle of 1943, some solutions had been found. These fixes included a rigid rotor system that eliminated the control reversal problem, a differential collective pitch control, a greater range of cyclic control, and new blades and blade pitch bearings. However, even these improvements could not overcome Leavitt's lack of confidence in flying the aircraft forward at speed. He refused to fly the critical, closed-circuit flight test and spent most of his time hovering or flying sideways. Something had to be done to get the project moving again. In May 1943 Colonel H. Franklin Gregory, the AAF's director of rotary wing projects, flew Igor Sikorsky's YR-4 helicopter into Platt-LePage's Eddystone, Pennsylvania, factory airfield. The YR-4 was demonstrating much better performance than the XR-1 and Gregory no doubt hoped its presence would spur Leavitt to action. The colonel spent some time at Platt-LePage reviewing the XR-1's difficulties.

On June 9, Gregory's patience ran out. He climbed into the XR-1 and successfully conducted the closed-circuit flight test himself at speeds near 161 kph (100 mph), with no serious difficulties. This was Gregory's first flight in the Platt-LePage helicopter and it led to serious questions about Leavitt's abilities as a helicopter test pilot. A short time later, Jim Ray, a top autogiro pilot, succeeded Leavitt as XR-1 chief test pilot. Ray resumed testing at a brisk pace and worked the helicopter up to 97 kph (60 mph) in level flight. All seemed well until July 4, 1943. During a speed run, one rotor disintegrated and sent Ray crashing to the ground. Platt and LePage must have been frustrated to discover the cause was basic human error compounded by bad judgement.

Prior to the flight, the Platt-LePage shop had improperly attached an aerodynamic fairing to the top of one rotor hub. The engineering department was evaluating these devices to determine whether they could smooth out the airflow around the two main hubs. The installation error was caught but not fixed when the shop supervisor objected. He argued that because the next test flight would be flown at slow speed, the loose fairing posed no danger and the test program should not be unnecessarily delayed. The test proceeded. Alan Price, chief engineer, saw the fairing begin to fail, and had started for LePage's office to stop the flight when the accident occurred.

Ray was seriously injured and the airframe badly damaged. More than a year passed before the XR-1 was cleared to fly again. By then, Jim Ray had left the company but a new chief test pilot, Buck Miller, continued the flight tests.

The crash was a serious setback but it did not completely cripple the program. Soon after the AAF approved the project, Platt-LePage requested and received funding to build a backup test aircraft on October 29, 1941. This helicopter was designated the XR-1A and it incorporated improvements based on experience gained with the XR-1. Most noticeable was the change to a Plexiglas, bubble-type canopy over the cockpit that dramatically improved visibility. Engineers also swapped the seating arrangement and placed the pilot in back, behind the observer. This layout is today a worldwide standard for most military attack helicopters.

A new Pratt & Whitney R-985-AN-1 radial engine was also installed that provided a healthy increase in horsepower. The flight controls were also modified to correct problems that the XR-1 first encountered. Buck Miller took the new and improved XR-1A aloft on its first flight on October 27, 1943. He reported that it flew with better control and greater performance than the XR-1 had demonstrated on its first flight. The following summer, Miller completed a long cross-country flight to officially deliver the helicopter to the AAF. He flew in poor weather from the Platt-LePage facility at Eddystone, Pennsylvania, to the AAF test and evaluation center at Wright Field, Ohio. When Miller landed on June 20, 1944, he also reached the high point in the short flying history of the XR-1A. AAF test pilots continued to test the helicopter at Wright Field until October 26, 1944, when a pinion gear failed in the right rotor hub. The ensuing crash landing permanently grounded the aircraft and the AAF returned it to Platt-LePage.

The company deemed the remains not worth repair and consigned the aircraft to scrap. Ironically, former test pilot, Lou Leavitt, stepped in and bought the XR-1A wreckage at 4 cents per pound late in 1945. The Platt-LePage firm was in its death throes and strapped for cash. Leavitt repaired the aircraft and returned it to flying status under the auspices of his company, Helicopter Air Transport (HAT). The restoration effort did not help Leavitt's fortunes and the firm folded just as the work was completed. Now Leavitt needed quick cash so he sold the reborn XR-1A to Frank Piasecki for $1,500. Leavitt earned another $500 from Piasecki for completing the 12-minute delivery flight. Piasecki toyed briefly with the old helicopter, then grew concerned about its airworthiness. It never flew again but Piasecki recycled the basic airframe into another design, the PA-2B Ringwing tiltrotor mockup.

Only the two XR-1s were actually flown but Platt-LePage won a contract to build and fly seven examples of a pre-production version of the XR-1A called the YR-1A. The AAF wanted to conduct operational trials and compare the Platt-LePage design with the single-rotor Sikorsky types. However, no YR-1As were completed. The AAF Air Technical Service Command visited Platt-LePage on March 21, 1945, to access progress made on the XR-1 program. The previous day, military and government planners in Washington decided to cancel all contracts with Platt-LePage, and the Air Technical Service Command inspection team saw no reason to overturn that decision. The program was terminated because lateral control in the XR-1 and XR-1A was insufficient, the controls were too sluggish and there was excessive airframe vibration during turns.

Air Materiel Command reported that Platt-LePage was "inept in carrying out any research and development work and that [the company's] only hope of having a successful aircraft was through a hit-or-miss method." The AAF allowed Platt-LePage to continue flying the XR-1 as a prototype for their PL-9 helicopter. This new model was a scaled up version of the XR-1 that incorporated a separate engine to drive each rotor. The XR-1 flew until June 21, 1946.

An unusual spin off of the XR-1 project was its contribution to a fixed-wing aircraft, the Bell P-39 Airacobra (see NASM collection). Bell engineers mounted the P-39's inline engine behind the pilot and used a shaft to drive the nose-mounted propeller. When the AAF first fielded Airacobras in 1941, several were lost when the drive shafts failed. The AAF contracted with Platt-LePage to eliminate these failures, and the firm used its considerable experience with the long drive shafts that powered the XR-1 main rotors to solve the problem.

After grounding the XR-1 for good on June 21, 1946, the AAF transferred the historic helicopter to their growing historical aircraft pool and subsequently gave it to the Smithsonian Institution. The XR-1 is currently not restored. In 1999, specialists at the Paul Garber Restoration and Storage Facility reassembled the helicopter for the first time in more than fifty years and found this important helicopter in remarkable condition.

The history of Platt-LePage was short and troubled but the company did collect valuable information and pass it on to another helicopter pioneer, the McDonnell Aircraft Corporation. When the XR-1 flight test program began to falter in 1943, Platt-LePage had sought capitol investment from McDonnell. To pay for the infusion of cash, Platt-LePage gave McDonnell the rights to co-develop the twin-rotor concept. When the government cancelled the XR-1 and YR-1A programs in 1945, the firm began its death dive toward bankruptcy. The unique, Platt-LePage twin-rotor layout seemed destined to be forgotten but McDonnell continued to develop it. Taking lessons learned from the XR-1 and the PL-9 projects, McDonnell designed America's first twin-engine helicopter for the U. S. Navy. The McDonnell's XHJD-1 Whirlaway (see NASM collection) transport helicopter was outwardly very similar to the XR-1 but it was larger and heavier, and used a separate engine to power each rotor.

Though promising, the Whirlaway marked the end of the line for helicopters with two main rotors mounted on pylons. The Kellett XR-10 was also a twin-rotor, twin-engine aircraft but all major components were neatly and efficiently housed within the fuselage (see NASM collection for the XR-10 prototype, the Kellett XR-8). Kellett beat McDonnell and won a contract to build several pre-production versions of the XR-10. McDonnell built only one XHJD-1.

Platt-LePage was one of many American helicopter companies that failed during World War II. Igor Sikorsky's development of the single-rotor helicopter eclipsed the progress made by Focke and his imitators. However, Platt-LePage and the XR-1 had an impact that reached far beyond the war years. They served as a superb training ground for engineers that would go on to work at McDonnell, Piasecki, and other rotorcraft firms.

Rotor Diameter: 9.3 m (30 ft 6 in)

Length: 8.9 m (29 ft 4 in)

Weight: 2,147 kg (4,730 lbs)

Engine: Pratt & Whitney R-985-23 air-cooled radial, 440 horsepower

References and Further Reading:

Air Material Command Rotary Wing Branch. "Summary of Rotary Wing Projects of Aircraft Projects Section." 1947.

Gregory, H. Franklin. "Anything A Horse Can Do: The Story of the Helicopter." Cornwall, New York: Cornwall Press, 1944.

Labermont, Paul. "Helicopters and Autogyros of the World." New York: Philisophical Library, Inc., 1959.

LePage, W. Laurence. "Growing Up with Aviation." Ardmore, Penn.: Dorrance & Company, Incorporated, 1981.

Spencer, Jay P. "Whirlybirds: A History of the U. S. Helicopter Pioneers." Seattle: University of Washington, 1998.

XR-1 curatorial file, Aeronautics Division, National Air and Space Museum.

Correspondence with Jay Hendrickson

Roger D. Connor, Russell Lee, 8-3-00

The XR-1 was the first American military helicopter to takeoff and hover with good control. The work of German aircraft designer Henrich Focke inspired two American engineers, W. Laurence LePage and Havilland H. Platt, to design the XR-1. Focke's Focke-Wulf Fw 61 helicopter employed a pair of main rotors turning atop pylons, or outriggers, jutting away from both sides of a central fuselage. During the late 1930s, the Fw 61 was flown to set a number of helicopter world records. In February 1938, W. Laurence LePage witnessed the Nazi test pilot, Hanna Reitsch, fly the Fw 61 in front of several thousand people inside a Berlin sports arena called the Deutschlandhalle. Platt tried to negotiate with Focke to purchase the rights to build the Fw 61 under license but the German engineer insisted on too many restrictions and no agreement was reached.

Third Reich propagandists seized on the Fw 61 as a demonstration of Nazi technical prowess. Newsreel footage of the Deutschlandhalle flight circulated around the world, demonstrating to many that the helicopter was not only technically feasible, but that fascist Germany was leading the way in developing it. Other designers tried to duplicate Focke's success. In England, James Weir constructed two aircraft based on Focke's design principles, but neither aircraft flew as well as the Fw 61. Russian efforts to duplicate Focke's designs also failed.

Before teaming with Platt, LePage worked as an engineer on various autogiro projects for the Pitcairn Autogiro Company and the Kellett Aircraft Corporation. This experience was important because many of the critical design features necessary to build a practical helicopter were first developed and tested on the autogiro. Platt was a mechanical engineer who helped develop the automotive automatic transmission. He was also an outspoken advocate for vertical flight aircraft. At the end of 1938, the two men formed a company to design an improved variation of the Foche-Wulf Fw 61.

Month by month, the likelihood for world conflict grew and the U. S. Army Air Forces (AAF) began funding efforts to recover some of the ground lost to Germany in arms development. LePage had impressed U. S. government engineers with his film footage of Focke's achievements and he hoped this might spur federal investment in his helicopter projects. His efforts did gain the attention of AAF planners and members of the Congress. Pennsylvania congressman, Frank Dorsey, passed a bill in 1938 supporting helicopter research and development. The initial amount provided by the bill was $2 million dollars and it jump-started the American helicopter industry. Le Page may well have influenced Dorsey to pass this important piece of legislation.

When the U. S. Army Material Division published the first specifications for an AAF helicopter on August 25, 1939, Platt and LePage had already made considerable progress on several helicopter designs. In less than a year, they formed the Platt-LePage Aircraft Company and they completed more than half the design and construction of their first helicopter, the PL-3. The AAF helicopter evaluation board met on May 27, 1940, to review bids to build "a rotary wing aircraft in the interest of adequate national defense." A design based on the much-publicized Fw 61 held a clear advantage. Platt-LePage was chosen and accepted a government contract worth nearly $500,000 on July 10, 1940, to produce the PL-3 under the AAF designation XR-1.

Platt and LePage designed the XR-1 with a fuselage containing a two-place, tandem cockpit covered with sliding canopies. The pilot flew from the front seat and the observer sat behind him. The empennage consisted of a "T" stabilizer arrangement similar to the one utilized on the Fw 61. A Pratt & Whitney R-985-23 radial engine producing 440 horsepower was mounted behind the cockpit in the center of the fuselage. The rotors were mounted at the end of wing-like pylons that extended laterally and with some dihedral from the center of the fuselage. The cantilever wing pylons were designed to develop some lift in forward flight and reduce the disk loading (aircraft flying weight) bearing on the rotors. Landing gear consisted of two fixed main wheels on oleo struts extending from the rotor pylons and one tail wheel. All wheels could castor freely to ease ground handling. One problem addressed early in the design was downward visibility during vertical landings. The solution adopted then and still used today was to cover the lower nose section in Plexiglas.

Platt-LePage's XR-1 took to the air, restrained by a safety tether, on May 12, 1941. The first flight without a tether took place on June 23. From the outset several problems were evident. The aircraft was difficult to control and suffered from excessive vibration. One daunting problem was the automatic, collective pitch control system, which could cause control reversal, especially during turns. These control irregularities caused the company test pilot, Lou Leavitt, much concern and slowed the pace of flight-testing to a crawl.

Among the Platt-LePage engineering staff working on the control problem was a young engineer named Frank Piasecki. Piasecki later resigned from Platt-LePage and started his own successful helicopter enterprise. He built a rotorcraft called the PV-2 (see NASM collection) and flew it to earn the first U. S. civil helicopter license ever issued.

Control problems continued to hamper the XR-1 long after Piasecki departed. Platt and LePage were better managers than engineers and this greatly hampered efforts to improve the helicopter. But the middle of 1943, some solutions had been found. These fixes included a rigid rotor system that eliminated the control reversal problem, a differential collective pitch control, a greater range of cyclic control, and new blades and blade pitch bearings. However, even these improvements could not overcome Leavitt's lack of confidence in flying the aircraft forward at speed. He refused to fly the critical, closed-circuit flight test and spent most of his time hovering or flying sideways. Something had to be done to get the project moving again. In May 1943 Colonel H. Franklin Gregory, the AAF's director of rotary wing projects, flew Igor Sikorsky's YR-4 helicopter into Platt-LePage's Eddystone, Pennsylvania, factory airfield. The YR-4 was demonstrating much better performance than the XR-1 and Gregory no doubt hoped its presence would spur Leavitt to action. The colonel spent some time at Platt-LePage reviewing the XR-1's difficulties.

On June 9, Gregory's patience ran out. He climbed into the XR-1 and successfully conducted the closed-circuit flight test himself at speeds near 161 kph (100 mph), with no serious difficulties. This was Gregory's first flight in the Platt-LePage helicopter and it led to serious questions about Leavitt's abilities as a helicopter test pilot. A short time later, Jim Ray, a top autogiro pilot, succeeded Leavitt as XR-1 chief test pilot. Ray resumed testing at a brisk pace and worked the helicopter up to 97 kph (60 mph) in level flight. All seemed well until July 4, 1943. During a speed run, one rotor disintegrated and sent Ray crashing to the ground. Platt and LePage must have been frustrated to discover the cause was basic human error compounded by bad judgement.

Prior to the flight, the Platt-LePage shop had improperly attached an aerodynamic fairing to the top of one rotor hub. The engineering department was evaluating these devices to determine whether they could smooth out the airflow around the two main hubs. The installation error was caught but not fixed when the shop supervisor objected. He argued that because the next test flight would be flown at slow speed, the loose fairing posed no danger and the test program should not be unnecessarily delayed. The test proceeded. Alan Price, chief engineer, saw the fairing begin to fail, and had started for LePage's office to stop the flight when the accident occurred.

Ray was seriously injured and the airframe badly damaged. More than a year passed before the XR-1 was cleared to fly again. By then, Jim Ray had left the company but a new chief test pilot, Buck Miller, continued the flight tests.

The crash was a serious setback but it did not completely cripple the program. Soon after the AAF approved the project, Platt-LePage requested and received funding to build a backup test aircraft on October 29, 1941. This helicopter was designated the XR-1A and it incorporated improvements based on experience gained with the XR-1. Most noticeable was the change to a Plexiglas, bubble-type canopy over the cockpit that dramatically improved visibility. Engineers also swapped the seating arrangement and placed the pilot in back, behind the observer. This layout is today a worldwide standard for most military attack helicopters.

A new Pratt & Whitney R-985-AN-1 radial engine was also installed that provided a healthy increase in horsepower. The flight controls were also modified to correct problems that the XR-1 first encountered. Buck Miller took the new and improved XR-1A aloft on its first flight on October 27, 1943. He reported that it flew with better control and greater performance than the XR-1 had demonstrated on its first flight. The following summer, Miller completed a long cross-country flight to officially deliver the helicopter to the AAF. He flew in poor weather from the Platt-LePage facility at Eddystone, Pennsylvania, to the AAF test and evaluation center at Wright Field, Ohio. When Miller landed on June 20, 1944, he also reached the high point in the short flying history of the XR-1A. AAF test pilots continued to test the helicopter at Wright Field until October 26, 1944, when a pinion gear failed in the right rotor hub. The ensuing crash landing permanently grounded the aircraft and the AAF returned it to Platt-LePage.

The company deemed the remains not worth repair and consigned the aircraft to scrap. Ironically, former test pilot, Lou Leavitt, stepped in and bought the XR-1A wreckage at 4 cents per pound late in 1945. The Platt-LePage firm was in its death throes and strapped for cash. Leavitt repaired the aircraft and returned it to flying status under the auspices of his company, Helicopter Air Transport (HAT). The restoration effort did not help Leavitt's fortunes and the firm folded just as the work was completed. Now Leavitt needed quick cash so he sold the reborn XR-1A to Frank Piasecki for $1,500. Leavitt earned another $500 from Piasecki for completing the 12-minute delivery flight. Piasecki toyed briefly with the old helicopter, then grew concerned about its airworthiness. It never flew again but Piasecki recycled the basic airframe into another design, the PA-2B Ringwing tiltrotor mockup.

Only the two XR-1s were actually flown but Platt-LePage won a contract to build and fly seven examples of a pre-production version of the XR-1A called the YR-1A. The AAF wanted to conduct operational trials and compare the Platt-LePage design with the single-rotor Sikorsky types. However, no YR-1As were completed. The AAF Air Technical Service Command visited Platt-LePage on March 21, 1945, to access progress made on the XR-1 program. The previous day, military and government planners in Washington decided to cancel all contracts with Platt-LePage, and the Air Technical Service Command inspection team saw no reason to overturn that decision. The program was terminated because lateral control in the XR-1 and XR-1A was insufficient, the controls were too sluggish and there was excessive airframe vibration during turns.

Air Materiel Command reported that Platt-LePage was "inept in carrying out any research and development work and that [the company's] only hope of having a successful aircraft was through a hit-or-miss method." The AAF allowed Platt-LePage to continue flying the XR-1 as a prototype for their PL-9 helicopter. This new model was a scaled up version of the XR-1 that incorporated a separate engine to drive each rotor. The XR-1 flew until June 21, 1946.

An unusual spin off of the XR-1 project was its contribution to a fixed-wing aircraft, the Bell P-39 Airacobra (see NASM collection). Bell engineers mounted the P-39's inline engine behind the pilot and used a shaft to drive the nose-mounted propeller. When the AAF first fielded Airacobras in 1941, several were lost when the drive shafts failed. The AAF contracted with Platt-LePage to eliminate these failures, and the firm used its considerable experience with the long drive shafts that powered the XR-1 main rotors to solve the problem.

After grounding the XR-1 for good on June 21, 1946, the AAF transferred the historic helicopter to their growing historical aircraft pool and subsequently gave it to the Smithsonian Institution. The XR-1 is currently not restored. In 1999, specialists at the Paul Garber Restoration and Storage Facility reassembled the helicopter for the first time in more than fifty years and found this important helicopter in remarkable condition.

The history of Platt-LePage was short and troubled but the company did collect valuable information and pass it on to another helicopter pioneer, the McDonnell Aircraft Corporation. When the XR-1 flight test program began to falter in 1943, Platt-LePage had sought capitol investment from McDonnell. To pay for the infusion of cash, Platt-LePage gave McDonnell the rights to co-develop the twin-rotor concept. When the government cancelled the XR-1 and YR-1A programs in 1945, the firm began its death dive toward bankruptcy. The unique, Platt-LePage twin-rotor layout seemed destined to be forgotten but McDonnell continued to develop it. Taking lessons learned from the XR-1 and the PL-9 projects, McDonnell designed America's first twin-engine helicopter for the U. S. Navy. The McDonnell's XHJD-1 Whirlaway (see NASM collection) transport helicopter was outwardly very similar to the XR-1 but it was larger and heavier, and used a separate engine to power each rotor.

Though promising, the Whirlaway marked the end of the line for helicopters with two main rotors mounted on pylons. The Kellett XR-10 was also a twin-rotor, twin-engine aircraft but all major components were neatly and efficiently housed within the fuselage (see NASM collection for the XR-10 prototype, the Kellett XR-8). Kellett beat McDonnell and won a contract to build several pre-production versions of the XR-10. McDonnell built only one XHJD-1.

Platt-LePage was one of many American helicopter companies that failed during World War II. Igor Sikorsky's development of the single-rotor helicopter eclipsed the progress made by Focke and his imitators. However, Platt-LePage and the XR-1 had an impact that reached far beyond the war years. They served as a superb training ground for engineers that would go on to work at McDonnell, Piasecki, and other rotorcraft firms.

Rotor Diameter: 9.3 m (30 ft 6 in)

Length: 8.9 m (29 ft 4 in)

Weight: 2,147 kg (4,730 lbs)

Engine: Pratt & Whitney R-985-23 air-cooled radial, 440 horsepower

References and Further Reading:

Air Material Command Rotary Wing Branch. "Summary of Rotary Wing Projects of Aircraft Projects Section." 1947.

Gregory, H. Franklin. "Anything A Horse Can Do: The Story of the Helicopter." Cornwall, New York: Cornwall Press, 1944.

Labermont, Paul. "Helicopters and Autogyros of the World." New York: Philisophical Library, Inc., 1959.

LePage, W. Laurence. "Growing Up with Aviation." Ardmore, Penn.: Dorrance & Company, Incorporated, 1981.

Spencer, Jay P. "Whirlybirds: A History of the U. S. Helicopter Pioneers." Seattle: University of Washington, 1998.

XR-1 curatorial file, Aeronautics Division, National Air and Space Museum.

Correspondence with Jay Hendrickson

Roger D. Connor, Russell Lee, 8-3-00