Bell X-5

History of Bell X-5

The X-5 was an experimental single-seat, single-engine, jet fighter design prototype built by Bell Aircraft and was the first aircraft to use variable-geometry wings in flight. Its roots can be traced back to the German Messerschmitt Me P. 1101, from which the X-5 borrowed heavily in its overall design. As Germany began to abandon the ground in the final years of World War II, the jet P. 1101 was captured by U.S. ground forces. Although the P. 1101 was only 80 percent complete when it arrived in the United States, it used basic wing sweep principles to test various wing attitudes during its development. The fledgling German system, however, relied on changes to the wing sweep while the plane was still on the ground.

Only two X-5 prototypes were produced, the second was lost in the accident. The X-5 program was considered for the US/NATO low-cost tactical fighter program.

Rotor technology

In the X-5, the pilot has full control over the aircraft's wing movements during flight. This allows him to tailor the sweep to the action at hand, whether taking off, landing or cruising - increasing or decreasing the airframe's drag as needed.

The X-5 program went on to demonstrate the inherent viability of this technology in increasing top speed, reducing landing speed, and supporting better rates of climball using a wing system. The X-5 proved helpful for Americans to collect data on these different wing movements at subsonic and supersonic speeds.

The technology became the hallmark of upcoming Cold War-era fighter jets, such as Grumman's F-14 Tomcat, General Dynamics' F-111 Aardvark and Rockwell B-1 bomber. In addition, the British Panavia Tornado and the Soviet MiG-23/27 also use the "swing wing" method.

Birth of P. 1101

Messerschmitt Me P. 1101 itself emerged from the "Emergency Combat Aircraft Competition" launched by the German Aviation Ministry in mid-1944. The program essentially halted all bomber production and instead focused on high-performance defensive fighter jets to defend Germany from the relentless Allied bombing raids that were destroying its war infrastructure - Germany is now more or less In a defensive war, and the two fronts. New specifications for the development of the second-generation German jet fighter were set, and Messerschmitt joined within days. After completing two initial Messerschmitt designs, a third design was finally chosen for development. The hull of the P. 1101 is deep to accommodate the engine, associated piping, cockpit pressurization equipment, artillery armament and internal fuel.

The fuselage will feature a nose-mounted air intake to suck in the Heinkel-Hirth He S 011 turbojet to be installed, and the wings will be shoulder-mounted components with significant swept back - in fact, The wings are from the revolutionary Messerschmitt Me 262 jet fighter-bomber. The single-seat cockpit is mounted under a three-piece bubble canopy at the front of the fuselage and uses retractable tricycle landing gear - the main gear legs are from a Messerschmitt BF 109K fighter.

The fins are of the traditional type, with a vertical fin and applicable horizontal plane, all made of wood. The rear wing assembly is attached to a tapered boom formed on top of the engine exhaust.

Plans were made for cockpit armor, the delivery of four wire-guided missiles, and the recessed fuselage centerline location for a single bomb.

In order to further develop the P. 1101, it was decided to build a prototype of the P. 1101 V1 next to the wind tunnel and other ongoing data collection. The P. 1101 V1 design is also equipped with wings that can be adjusted to sweep its pre-flight and test wing sweeps at 35 and 45 degree angles. The wings were eventually adjusted for testing at 35, 40 and 45 degrees. If all goes according to plan, the first flight is scheduled for June 1945. All development and construction will take place at a little-known Messerschmitt factory in Oberammergau, in the Bavarian mountains of southern Germany.

The Allies were unaware of the facility, so the area was relatively free of Allied airstrikes.

P.1101 project ended

At the time, however, the Americans had come a long way in the region. Concerned that the P. 1101 data could fall into enemy hands, Messerschmitt employees microfilmed the information and hid it in four locations in neighboring villages.

When the Americans occupied Oberammergau on April 29, 1945, the Allies entered the areaindeed, they were somewhat surprised by the presence of the Messerschmitt facility. The Me P. 1101 V1 prototype was found hidden in a tunnel and quickly secured by the Americans.

Only later did Messerschmitt employees reveal the missing data and where it was found. By this time, however, French forces had entered and found the hidden P. 1101 data, which was subsequently returned to French authorities. A joint virtue-German effort led by Robert Woods of Bell Aircraft and Waldemar Walter of Messerschmitt to ensure microfilm and completion of P.1101 fell on deaf ears - the French seem to have no interest in them helping the former conquistador .

P. 1101's new home

Thus, the P. 1101 entered the US market. During her journey, she encountered countless abuses at the hands of the team responsible for transporting her. Not only did exposure to these elements take a toll on the P. 1011 body, but it was basically managed manually by the founding GIs who were hungry for photo opportunities.

The situation got worse when the P.1101 prototype airframe fell from the transporter - suffered enough damage to ensure that the V1 prototype could never be flown. Still, Bell Aircraft continued to strip the P.1101 down to the seams, outfitting the V1 with fake cannon weapons along the sides of the fuselage and American Allison J35 turbojets.

The P. 1101 V1 remained in valuable static ground testing before being sent to scrap burners sometime in the 1950s - ending the legacy of German aircraft.

Bell unveils new X-5

Robert Woods and Bell Aircraft introduced a similar X-5 in the early 1950s. The main difference from Bell mounts is the use of variable geometry wings in flight, which is achieved by a set of electric motors in a system designed by Bell engineers. The wing arrangement allowed the X-5 to adjust the wing sweep as needed between three preset positions of 20, 40 and 60 degrees, making it a more complex German form. The first prototype (50-1838) was completed on February 15, 1951 and flew for the first time on June 20, 1951. The second prototype (50-1839) flew in the air on December 10, 1951.

The two airframes made about 200 flights in total, with the first prototype alone making 133 flights. All three wing pivot positions were successfully tested on the ninth flight of the first prototype.

Specification

The X-5 is powered by an Allison J35-A-17 turbojet engine rated at 4,900 lbs. Top speed is between 690 and 716 mph, and cruising speed is around 600 mph. Reported service is capped at 50,700 feet (hence the pressurized cockpit), and the range listed is between 500 and 750 miles.

With full fuel, her empty weight remained at 6,336 pounds and her maximum takeoff weight (MTOW) was 9,980 pounds. No weapons were ever installed. Her variable wing sweep gives her a wingspan of 32 feet 9 inches when extended and 22 feet 8 inches when swept.

X-5 Project Tragedy

In practice, it soon became apparent that the X-5 had inherited some particularly severe stall-spin instability characteristics - perhaps the price of such a project being based on an incomplete German program. The reason is believed to be the positioning of the tail section in the design, reinforced by the placement of the vertical tail itself. As the wing sweep changes, the overall aerodynamics of the aircraft change substantially. The resulting action could have thrown the plane into an irreversible spin - which eventually happened on October 14, 1953 - a second prototype lost in this spin while turning its wings 60 degrees, Air Force test flight The death of Captain Ray Popson.

As a result, the program was shelved and eventually canceled by the USAF, undermining any chance of the X-5 becoming the low-cost tactical fighter the Americans envisioned. However, testing of the first prototype continued into 1955, and the aircraft remained in service for the remainder of the fighter's tenure in early 1958 - and its variable sweep proved helpful in keeping up with the various others being developed. airplane.

Beyond X-5

The remaining Bell X-5 was handed over to the National Museum of the United States Air Force in Dayton, Ohio in March 1958 as part of the R&D Gallery at Wright-Patterson Air Force Base, where it still stands today .

Some of the flight data collected from the X-5 program was used directly in the development of the Grumman F-14 Tomcat and General Dynamics F-111 Aardvark "rotor" fighters, although the special inner wing became the Bell Sweep mechanism for this Two advanced aircraft designs have been completely redesigned.

It should be noted that the Saab 29 "Tunnan" bears a striking resemblance to the Messerschmitt Me P. 1101 and Bell X-5.

Specification

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