"On This Day" In Engineering History

On this day in engineering history, the first McDonnell-Douglas DC-10 emerged from the company's final-assembly hangar in Long Beach, California. The debut of this wide-bodied jet transport was witnessed by 1,000 guests, including representatives of the 15 airlines that had placed orders for an aircraft that McDonnell-Douglas hoped would compete with the Boeing 747, Lockheed L-1011, and Airbus A300. Tragically, however, the DC-10 may be best remembered for a series of well-publicized plane crashes during the 1970s.

Designing and Building the First DC-10

Registered as N10DC, the first McDonnell-Douglas DC-10 was the product of new design and manufacturing processes. In addition to wooden mockups, aircraft designers built a dimensionally accurate, full-scale metal model that included the fuselage, tail fin, and wing junction. According to Gunter Endes, author of the 1998 book McDonnell Douglas DC-10, this technique "allowed the accurate fitting of electrical wiring, piping, ducting, insulation blankets and other linings prior to production." During production, five-axis, numerically-controlled milling machines were used to produce large, machined parts. According to Endes, 70 of these machines ran 24 hours a day, six days a week.

Large Loads and Long Hauls

The McDonnell-Douglas DC-10 was designed to carry as many as 380 passengers on long-range routes up to 3,800 miles. With a top speed of 600 miles per hour (mph), the wide-bodied jet featured three General Electric (GE) turbofan engines. Two of these engines were mounted on underwing pylons while the third was mounted at the base of the vertical stabilizer. The original engine model, GE CF6-6D, provided 40,000 pounds of thrust (lbf). The final DC-10 variant, the DC-10-40, used Pratt and Whitney JT9D-59A engines with 53,000 lbf. Today, the U.S. Air Force uses a modified DC-10-30 as an air-to-air tanker. With a maximum fuel load of 356,000 lbs., the KC-10 Extender has been in active service since 1981.

Maintenance Matters: The Safety Record of the DC-10

Although the lifetime safety record of the DC-10 was comparable to those of other heavy passenger planes, the aircraft may be best remembered for its brief grounding by the U.S. Federal Aviation Administration (FAA) in the summer of 1979. On May 25th of that year, an American Airlines DC-10 (Flight 191) crashed shortly after take-off near Chicago when a pylon-mounted engine separated from the aircraft. After examining cracks in the wing pylons of other DC-10-10s, FAA inspectors determined that the cause of the Chicago crash was an improper maintenance procedure in which mechanics used a forklift to remove both the engine and the pylon. Critics of the DC-10 remained skeptical about the aircraft's design, however, and noted past problems with the plane's cargo doors and hydraulic system.

Resources:

http://www.af.mil/history/weekinhistory.asp

http://www.super70s.com/super70s/Tech/Aviation/Aircraft/DC-10.asp

http://www.amazon.com/gp/reader/0760306176/ref=sib_dp_pt#

http://www.aviationexplorer.com/dc-10_facts.htm

http://en.wikipedia.org/wiki/McDonnell_Douglas_DC-10

http://widebodyaircraft.nl/chro1976.htm

On this day in engineering history, the U.S. Air Force launched the first operational X-17, an all-solid-fuel, three-stage, re-entry rocket built by Lockheed. Data from this and other X-17 research flights was used in the design of nose cones for intercontinental ballistic missiles (ICBMs). During the 1950s, the United States and Soviet Union raced to be the first to develop these long-range rockets, which could deliver nuclear payloads. Although the Soviets trumped the West with the success of their R-7 rocket in August 1957, the U.S. would launch its first Atlas ICBM several months later.

Lockheed Engineers Get the Job Done

A research rocket, the Lockheed X-17 enabled the U.S. Air Force to determine how an ICBM's nose cone would react during high-speed re-entry through Earth's atmosphere. By studying flight data, American rocket scientists determined the best size, shape and aerodynamic characteristics for re-entry vehicles with nuclear payloads. In January 1955, the Air Force awarded Lockheed a contract for the design and construction of the X-17. Using existing rocket motors and a simple control system, Lockheed engineers were able to provide a quarter-scale proof-of-concept vehicle in May 1955. The full-scale version of the X-17 that was launched on July 17, 1956 was 40-ft. long and weighed 12,000 lbs.

Powered by Thiokol

The Lockheed X-17 featured three solid-propellant rocket stages. Powered by a Thiokol XM20 motor, the first stage featured four stabilizing fins and two externally-mounted, spin-stabilization motors. Measuring 31 inches in diameter, the first stage was a modified Sergeant missile that produced 48,000 lbs. of thrust for 28 seconds. After reaching an apogee of approximately 500,000 ft, the X-17 pitched over for a nose-down re-entry and achieved first-stage separation between 70,000 and 90,000 feet. Measuring 17 inches in diameter, the X-17's second stage then engaged its three Thiokol XM19 Recruits for 1.53 seconds. Each of these Thiokol motors provided 33,900 lbs. of thrust.

Blunt is Best

The third and final stage of the X-17 measured 9.72 inches in diameter and was powered by a single, solid-fueled, XM19E1 Thiokol Recruit. Depending on the re-entry angle, the X-17 achieved a speed between Mach 11 and 14.5. To test different nose cone designs, these missiles used hemisphere, cubic paraboloid and blunt shapes. Ultimately, Lockheed and the U.S. Air Force determined that blunt nose cones provided the best shape for the Atlas ICBM.

Resources:

http://www.astronautix.com/lvs/x17.htm

http://www.spaceline.org/rocketsum/x-17.html

http://en.wikipedia.org/wiki/ICBM

On this day in engineering history, John Glenn flew an F8U-1 Crusader from California to New York in 3 hours, 23 minutes and 8.4 seconds, thus setting a new speed record for transcontinental flight. Glenn, a Marine Corps fighter pilot who later became the first American to orbit the Earth, also took the first continuous, transcontinental photograph of the United States as part of Project Bullet. Although John Glenn's mission is sometimes billed as "the first supersonic, transcontinental flight", his F8U-1 Crusader did not travel at supersonic speeds the entire way. Rather, Glenn made the first transcontinental flight to average supersonic speeds.

Chance-Vought and Pratt and Whitney

The F8U-1 Crusader that Glenn piloted was a single-engine, carrier-based aircraft with a top speed of Mach 1.2 at 30,000 ft. and a climb rate of 25,000 ft./min. Built by Chance-Vought of Dallas, Texas, Glenn's F8U-1 came equipped with a Pratt and Whitney J57-P4A engine that could produce 10,900 pounds of static thrust at sea level and 16,600 pounds in afterburner. To comply with the U.S. Navy's 1955 requirement that all carrier-based aircraft be capable of in-flight refueling, the F8U-1 featured a refueling probe on the starboard side of the fuselage, aft of the cockpit. During three in-flight replenishments, Glenn's speed dropped to approximately 350 mph.

The Ensign Eliminator

The most notable aspect of the F8U-1 Crusader's design was a variable-incidence wing which corrected landing problems with Chance-Vought's F7U Cutlass, an earlier carrier-based aircraft that critics dubbed the "Ensign Eliminator". To meet the requirements of carrier-deck operations, the Crusader's wing could pivot seven degrees to permit a higher angle of attack, thus reducing the approach and take-off speed. This feature also kept the fuselage level, protected the pilot's forward field-of-view, and eliminated the need for the lengthy nose gear of the F7U. Jacked-up by a hydraulic actuator and backed-up by a pneumatic mechanism, the Crusader's wing-raising system hinged on the rear spar and locked into place with a pilot-controlled handle.

Johnny Dropped a Bomb!

On July 16, 1956, Major John Glenn of the United States Marine Corps (USMC) departed the Naval Air Station (NAS) at Los Alamitos, California for a historic flight to Floyd Bennett Field, New York. His flying partner, U.S. Navy Lieutenant Commander Charles Demmler, was forced to abandon the transcontinental speed run after his own F8U-1 Crusader was damaged during in-flight refueling. While en route to New York, Major Glenn is said to have flown over his hometown of Cambridge, Ohio. According to one account, a child ran to Glenn's parents' house shouting "Johnny dropped a bomb!" as a sonic boom rocked the city.

Resources:

http://en.wikipedia.org/wiki/John_Glenn

http://www.aeroengineer.net/history/f8/f8bullet.html

http://home.att.net/~jbaugher1/f8_2.html

http://www.voughtaircraft.com/heritage/products/html/f8u-1.html

http://www.vectorsite.net/avcrus_1.html

On this day in engineering history, the U.S. Air Force performed the first test in Project Whoosh, a series of experiments that were designed to evaluate escape from an aircraft traveling at Mach 2. In the years after World War II, advances in aerospace technology produced jet planes that could travel at speeds greater than 500 mph. Pilots who flew at such high velocities were often unable to escape from their aircraft, however. Indeed, from 1949 to 1956, only 20% of pilots who ejected did so without harm. As the U.S. military competed in both the Cold War and the Space Race, aerospace biology and the design of better ejection seats became important fields of study.

Missiles and Sleds

In the early 1950s, the U.S. Air Force established an Aeromedical Field Laboratory (AMFL) at Holloman Air Force Base (AFB) near Alamogordo, New Mexico. Although Holloman AFB was involved mainly in missile research, including work with captured V-2 rockets, it also featured a 3,550-foot rail track for deceleration experiments. Led by Lt. Colonel John Paul Strap, the Alamogordo AMFL recruited human test subjects who volunteered to ride rocket-propelled sleds on missions that subjected participants to breaking forces around 35 g's. For the most dangerous experiments, however, animal test subjects were used.

Sonic Wind

Armed with higher-speed sleds called Sonic Wind 1 and Sonic Wind 2, the Air Force conducted a series of experiments to study survival limits for deceleration, windblast, tumbling, and other factors. Many of these experiments involved chimpanzees, most of which were seriously injured or killed while testing helmets, head rests, and windshields. For example, a monkey about Sonic Wind 1, a decompression sled built by Northrop Aircraft, traveled at 400 mph before coming to an abrupt stop that caused severe head trauma and death. A chimpanzee aboard Sonic Wind 2 met a similar fate when a helmet designed by Protection Inc. failed before Mach 1.7 was even achieved.

Project Whoosh

Project Whoosh took supersonic travel off the track and into the skies. According to the NASA History web site, this phase of Air Force research ejected chimpanzees from Cherokee missiles taken aloft by B-29 bombers. Once the aircraft reached an altitude of approximately 6 miles, the Cherokee was dropped and descended by parachute to about 5 miles, when a solid-fueled rocket motor accelerated the missile to supersonic speeds. The chimp was then ejected from an open seat.

Beginning with the first test of Project Whoosh on July 8, 1955, all of the chimpanzees died because of equipment failures with either the parachute system or ejection seat. "Nevertheless," the NASA web site notes, "this project was not a total loss" since "the failures were instructive". Eventually, "the work performed on Whoosh led directly to further ejection experiments at the Supersonic Military Air Research Track, Hurricane Mesa, Utah."

Resources:

http://history.nasa.gov/afspbio/part4-4.htm

http://www.releasechimps.org/harm-suffering/research-history/air-space/

http://books.google.com/books?id=xSdHVIpsrKkC&pg=PA107&lpg=PA107&dq=project+whoosh+&source=web&ots=bMHjUWt4u0&sig=H7gtet-_WdC_aBGCT6MuJ-hGZeE&hl=en&sa=X&oi=book_result&resnum=10&ct=result

http://historytogo.utah.gov/utah_chapters/utah_today/hurricanesamgavepilotsasafetyedge.html

http://www.designation-systems.net/dusrm/app4/cherokee.html

On this day in engineering history, U.S. President Jimmy Carter cancelled production of the B-1A bomber, a long-range aircraft that was designed to carry nuclear payloads deep within enemy territory. A former nuclear engineer and submariner, Carter cancelled the long-running B-1 program to focus development dollars on cruise missiles that could be launched from Navy ships or dropped from existing Air Force bombers such as the B-52. American cruise missiles would need carriers, however, as the Department of Defense (DoD) reminded Congress in several studies during the late 1970s. Ultimately, Carter's successor, President Ronald Reagan, would authorize the development of the B-1B – a long-range bomber with cruise-missile capabilities. As aviation historian Walter Boyne notes, however, "about 85 percent of the B-1B's airframe was common to the B-1A".

"The B-1B bomber," Boyne explains, "probably had a longer gestation period than any aircraft in aviation history." During the 1960s, the Air Force conducted several studies to develop a long-range aircraft that could replace the Boeing B-52 Stratofortress, a jet-powered subsonic bomber whose original contract dated back to 1946. These projects included the subsonic low-altitude bomber (SLAB), the low-altitude manned penetrating system (LAMPS), and the advanced manned strategic aircraft (AMSA). Although Secretary of Defense Robert McNamara favored intercontinental ballistic missiles (ICBMs) over manned bombers, AMSA mandated the development of an aircraft with supersonic capabilities at high altitudes and near-sonic capabilities at low altitudes. In 1969, AMSA was renamed the B-1A. A year later, North American Rockwell was chosen to build 244 aircraft with General Electric as the engine contractor.

Although only four B-1As were ever built, the bomber's specifications were impressive. The B-1A stood 150.2-ft. long and 33.6-ft. high, and could shoulder a maximum takeoff weight of 389,000-lbs. Approximately 115,000-lbs. of this amount was dedicated to armaments. Powered by four F-101 GE-100 turbofan engines with afterburners, the B-1A bomber boasted 30,000-lbs. of thrust per engine. The aircraft was designed to achieve a maximum speed of 750 mph at an altitude of 500 ft.; 1,320 mph (Mach 2.0) at 50,000 ft.; and reach a cruising speed of 648 mph at 50,000ft. With a range of 5,300 miles un-refueled, the B-1A could reach a ceiling of approximately 30,000 feet while carrying a crew of four: aircraft commander, pilot, offensive systems officer, and defensive systems officer. Unlike with other large aircraft, the crew used fighter-type control sticks instead of large control wheels.

Resources:

http://findarticles.com/p/articles/mi_qa3897/is_200504/ai_n13498079

http://www.globalsecurity.org/wmd/systems/b-1a.htm

http://www.fas.org/nuke/guide/usa/bomber/b-1a.htm

http://www.aerospaceweb.org/question/history/q0043.shtml