The Last Tristar

Rajan Khanna/Business Manager

In the late 1960s, Lockheed attempted to create an airliner more advanced than any other airliner before it. The result was the Lockheed L-1011 TriStar. The TriStar was the third wide-body aircraft to enter commercial service, after the Boeing 747 and McDonnell Douglas DC-10. It had a range of over four thousand nautical miles and could seat 400 people in three cabins. The three engine aircraft used Rolls Royce RB211 engines which are still in use today on other aircraft such as the Boeing 747-400 and Boeing 757 family.

The aircraft was the first wide-body aircraft to receive FAA certification for auto landing. It could land itself without any forward visibility. It also had a special Direct Lift Control system (DLC). The DLC allowed smooth approaches without much control input by deploying spoiler panels during final approach. Unfortunately, the advanced nature of the aircraft did not sell well enough and the plane was deemed a failure.

Even though the aircraft was a failure commercially, there is still one flying today: Northrop Grumman’s L-1011 Stargazer. The Stargazer is a specially modified L-1011 that carries the Pegasus rocket. This specially modified L-1011 was purchased from Air Canada in 1992 and converted to carry the Pegasus Launch System. The interior of the aircraft was completely stripped to reduce the weight so it could carry the 50,000 lb rocket. On the bottom deck, which was meant for the galley during it’s commercial service, Northrop Grumman fitted external fuel tanks to chill the fuel for the rocket. The cockpit was not retrofitted with a glass cockpit and still retains the orignal steam gagues and even has a place for a flight engineer. The engineers did put a release switch to drop the Pegasus rocket during launch. The rocket itself is a feat of engineering. It is an extremely capable air-launched rocket which carries microsatellites to low earth orbit. The propulsion system is completely solid which keeps it’s cost low. It has launched 38 times sucessfully and carried payloads such as NASA’s CYGNSS Mission. The Pegasus is the world’s first privately developed space launch system, first launching in 1990.

The mission profile for the Pegasus rocket starts at the Cape Canaveral Air Force Station Skid Strip. The L-1011 takes off and climbs to 39,000 feet over open ocean. The rocket is then released where it falls for five seconds and then ignites the first stage. Shortly after ignition, the rocket reaches maximum dynamic pressure. at 77.5 seconds into the mission, the first stage burns out and is jetisoned. At 93.3 seconds, the second stage ignites and burns for another 70 seconds. The spacecraft then coasts for over five minutes. The third stage ignites and burns for 30 more seconds to deliver the payload to it’s intended object. Usually, the Pegasus rocket can deliver its payload in under ten minutes.

The next mission for Pegasus is NASA’s ICON. ICON is NASA’s Ionospheric Connection Explorer. The satellite explores the ionosphere of the Earth and provides in-situ measurements. This location is difficult for spacecraft to traverse due to the variable drag on the spacecraft. The mission’s goal is to learn more about the ionosphere and assist in advances in technology that rely on signals that pass through it. ICON will fly at an orbit inclination of 27 degrees and an altitude of 360 miles. It’s period will be 97 minutes.

The Space Sciences Laboratory at The University of California Berkeley is responsible for the mission operations and data processing. The Space Sciences Laboratory will be the primary ground station, with others based in Singapore, Hawaii, Chile and the continental United States.

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