Posted by Wes Bradford on Mar 27, 2018

Tapio Kartiala is retired after over 45 years experience as an aerospace structural engineer. He presented his experiences in advanced aircraft design at the Lockheed “Skunk Works”.

 It was started in 1943 by Lockheed engineer Kelly Johnson when his company was asked to design a jet fighter to counter a rapidly growing German jet threat in World War II. One month later he hand-delivered a proposal and began work “on a handshake” (the formal contract arrived 4 months after the work had begun). His team designed and built the first XP-80 Shooting Star in 143 days, by “breaking the rules and challenging the bureaucracy”. The effort was top-secret and operated in a rented circus tent near a malodorous manufacturing area, so one of the engineers answered the phone as “Skonk Works” (from the “Li’l Abner” comic strip). The name “Skunk Works” was adopted as its trademarked designation for the advanced aircraft design unit, and it is still an active team of Lockheed Martin.

Tapio outlined the process of new aircraft design, through the conceptual, preliminary, and detailed phases. The engineering constraints include the aircraft’s purpose, regulations, financial availability, and environmental and safety requirements. The work is divided into wing design, fuselage, propulsion, weight limitations, and structural strength. While a bridge is typically designed to sustain 5 times its expected maximum load, an aircraft is allowed only 1½ times its maximum expected aerodynamic loading, due to weight limitations.

Tapio reviewed 3 aircraft. The U-2 spy plane was flown at 70,000 feet and could fly for 14 hours. At that altitude, a major design problem was preventing fuel evaporation from the low pressure at near-vacuum. It could fly higher than Soviet missiles could reach, until a newer missile design shot one down over the Soviet Union, with the pilot Gary Powers being held as prisoner until exchanged for a Soviet prisoner from the US 3 years later.

The SR-71 Blackbird can fly at 80,000 feet and 2100 mph (almost 3 times the speed of a rifle bullet). It has never been hit by hostile fire because of its speed. It is made of titanium to sustain high surface temperatures (up to 400-1200°F during flight). It takes on most of its fuel in mid-air refueling because a full fuel load makes it too heavy for takeoff. (Engineers were still using slide rules when its design began.)

The F-117 Stealth fighter has many flat surfaces at odd angles to confuse radar imaging, and also a special chemical coating to absorb radar signals. It is the stealthiest aircraft ever built.