Flying Wings & Winglets

Courtesy of US Air Force

Through the design thinking course I am taking at Stanford University, our professor Barry Katz handed us an interesting question. He asked his students: Using a mass-produced object of your choice, see if you can make sense out of the Modernist mantra “Form follows function.

Meticulously I thought of my childhood nostalgia to aircraft wings. “The most efficient form for any flying machine is just the wing,” said professor Ian Poll an Aerospace Engineering at Cranfield University. But what I want to tell you about is the magnificent impact of the flying wings and winglets in our American history.

Flying Wings

The flying wing came to an age in 1930s when the Horten brothers invented the flying wings for the new Nazi regime in Germany. By 1940s, another German aircraft designer called Alexander Lippisch invented his own flying wings, the Me 163, which crossed 600 mph. But the Horten brothers went further on 61 feet wingspan aircraft called Ho 229, with its high speed potential at 620 mph the fastest aircraft in WWII — that goes all to the efficiency of the flying wing design.

While the Germans were busy on building their own flying wings, a 40 year old American aircraft designer Jack Northrop was working on designing fly wings on his own in California. His potential was to minimize the tail and fuselage, later he got rid off the tail. In December 1942, his N-1M took its first step on the air, the successful launch followed by three decades of developing Northrop’s flying wings. The Germans failed the war and Northrop kept going on developing his ideas. In 1946, he built the YB-35 flying wing powered by four turboprop engines, flew at speed of 400 mph. Many observers have seen it as the bomber of the future. It had a wingspan circa 196 feet but it had a problem, its speed on long range cruise was slow as 195 mph.

A year later, 1947, he introduced his new YP-49 flying wing, powered by 8 Allison jet engines and at 172 feet wingspan it was capable of flying 400 mph at a ceiling of 40,000 feet. His flying wing was not only functioned as a bomber but also as a passenger aircraft. It carried 80 passengers with observation lounge and it crossed America in 4 hours. Yet, the YP-49 had difficulties on flying with a lot of computer controls. The US Air Force found it unstable and dangerous. With no quibble, in 1949, the US government ordered all YP-49 to be destroyed.

During that time, the world was entering a new era of nuclear power. The Soviet Union was building a huge arsenal of weapons. The US planned on flying high to avoid the advanced radar sounds of the Soviet air defense, but it was too high that it was impossible to target. The US wanted something invisible to invade the Soviet system. Something creative that can deny the information that comes from aircraft to the enemy radar.

30 years after destroying Northrop’s flying wings, in 1970 the US government selected the Northrop flying wing team to come up with a feasible design. The project was top secret known as Black Program. Even the Congress had no idea how much money was being spent. The project took 18 years to build, in 1988 Northrop unveiled his new aircraft the B-2 Stealth Bomber in Palmdale, California. Not only the audience was incredibly amazed but the whole nation and the world. Every American was proud, it put the US Air Force in a global power that no one on Earth has and no one in history have ever drawn. “by God, it is American!” said Dr. Aryeh Nusbacher at Royal Military Academy Sandhurst. By the time the B-2 was ready to roar the sky, Soviet Union was gone forever! There was no mission to bomb anywhere!

The B-2 flying wing had over 130 onboard computers controlling every element of the aircraft. It is invisible to the radar, its smooth surface and shape consist of curve yet not consistently identical. The B-2 can continuously change shape from whatever angel it is viewed thereby confusing the radar. Coated with radar absorbent secret materials (RAM) further reduces its detection from the enemy. It has 172 ft. wingspan, it weight 154,000 lbs. empty and 375,000 lbs. loaded. Approximately, 80% of its structure is made of carbon fiber (lighter than aluminum and stronger than steel.) It has special exhaust vents on top of its wings which when its hot gases are mixed with cool air makes it to exceed the speed of sound. The B-2 top speed is 680 mph at service ceiling of 50,000 ft, and it can fly 6,000 miles without refueling. It can carry 40,000 lbs. of laser-guided nuclear bombs and missiles.

In 1999, the B-2 took its first battle to the former Yugoslavia. It approved its efficiency on air strike than any other strike in history. “Flew less than 1% of total missions but dropped 11% of the bombs” said Bill Clinton.

Winglets

The B-2 still improves its efficiency but now I want to introduce you to what is happening on the edge of the wing. Winglets are type of wing tips devices that provide efficiency in the performance of the aircraft wing. There are two kind of winglets: Blended and Split Scimitar.

The pressure of the vortex on the wings cause high dragging which means more fuel to burn. In order to reduce the vortex, aerodynamicists came out with a design concept on creating a blended winglet as an extension on the wingtips. These blended winglets approved to reduce the pressure of the vortex and cause less dragging which means less fuel to burn. The story interestingly goes beyond that. So, we created the magnificent design of winglet but fortunately the story continued to grow to benefit everybody. The winglets began to reduces the noise on takeoff by 6.5% it even reduced burn of fuel (6% reduction in CO2 and 8% reduction in NOx.) For example, the most popular flight that is used at all airports is Boeing 737. Its winglets reduce 1,163 tons of CO2 per year per airplane, which can save up to $11,000 per year per airplane. This small smart touch on the wingtip, known as Winglet, enabled all aircrafts to take off with increased payload. Boeing 737 equipped with winglet can achieve 1,200 ft. higher optimal altitude than non-winglet equipped for same aircraft. The blended winglet can increase the age of the wing, maintenance reduced up to 3% at takeoff thrust and 4% at cruise thrust.

In 1970s Richard Whitcom, American aeronautical engineer, was the first to propose the concept of winglets (vertical or near vertical.) It took three decades for the aircraft industry to take advantage on his concept. In 2011, the significant aerodynamic improvement to winglet took to a high level when the Boeing Commercial Airplanes introduced the Boeing 737 MAX 200. The new winglet is split up and called “Split Scimitar Winglet.” The modification from the blended winglet was made on replacing the aluminum winglet tip cap with a new scimitar winglet tip cap. The Split Scimitar Winglets have retrofitted on many aircrafts such as Boeing 737 MAX which caused 2% reduction on its drag. This 2% improvement could save 45,000 lbs. of its fuel per year, enable to increase its payload to 2,500 lbs. or increase its range up to 75 nautical miles. It even can arry more 12 passenger per route in total of 162 passenger compared to its competitor, with 14% reduction in fuel with much less noise.

In 2013, the low fare airline grew 27% on Boeing 737 MAX. Today more people can travel on air seats compared to 1995. This achievement comes to the core believe as legend Louis Sullivan said it: “form must ever follow function.” The form of the winglets and flying wings has not only a fella function but improvement after improvement after improvement with continuum increase in efficiency as well. “These airplanes are not only fuel efficient but they are operationally more reliable, they are environmentally more responsible, and they are very customer pleasing” said Jeff Smisek, president and CEO of United Continental Holdings.

My nostalgia to aircraft wings has proven to me that they are aesthetically and functionally improving our life from many aspects.