Thirty years ago NASA carried out a controlled impact demonstration, known as “the crash in the desert”, in which researchers essentially crashed a Boeing 720 into an dry lake bed. We take a look at every aspect of this crazy experiment and what the aerospace engineers learnt after completing it.
The impact occurred on the morning of the 1st of December 1984, after spending nine minutes in the air.
Although crashing a plane sounds (reasonably) easy, preparation began four years before the final test-flight occurred. During testing the Boeing spent a total of 16 hours and 22 minutes in the air, including 10 takeoffs and 69 approached landings.
The controlled impact took place on Rogers Dry Lake, at the Dryden Flight Research Facility in Edwards, California. This is an area of arid land located 16 miles south-east of the Mojave Desert.
The facility was originally named after Hugh Dryden, a prominent aeronautical engineer who passed away in 1965. Unfortunately for Dryden and his family, the site was renamed on the 1st of March 2014, this time after Neil Armstrong.
The controlled impact was a joint project between NASA and the Federal Aviation Administration (FAA). The Langley Research Center, Dryden Flight Research Center and General Electric were also involved in the experiment.
The aircraft was flown by NASA research pilot Fitzhugh Fulton. Fulton started his career as a pilot in the US Airforce, where he took part in hundreds of combat missions over Berlin and North Korea for which he earned a Distinguished Flying Cross and five Air Medals.
After retiring from service Fulton became a test pilot for the Air Force, where he was involved with the B-58 supersonic bomber. During these experiments Fulton set an international altitude record by flying at a height of 26 kilometres (85,301 feet) in 1962.
Fulton moved to NASA in 1966 and earned the NASA Exceptional Service Medal for his contribution towards the Boeing 747 Space Shuttle Carrier Aircraft. In 1980, he started work on the Controlled Impact Demonstration.
In 1960 the FAA purchased a brand new Boeing 720 to use as a training aircraft. After spending over 20,000 hours in the air and performing 54,000 takeoff and landing cycles, it started looking a bit tired, so was given to the Dryden Flight Research Center in 1981.
NASA adapted the plane to fly via remote control, similar to an unmanned drone. The plane was controlled from a model cockpit and a CRT monitor (pictured above). The first full-scale test flight was cancelled due to a failure with the uplink connection; if the uplink had failed in-flight, Fulton would have lost control of the aircraft and the Boeing 720 would be independently roaming US airspace.
On the day of the last flight, the aircraft took off and climbed to a height of 700 metres. Upon approaching the specially designed runway, Fulton was given the go-ahead, data acquisitions systems were activated and the aircraft was committed to impact.
As the plane passed the point of no return, 46 metres up, the aircraft made contact with the ground. The initial plan was for the plane to land completely level, allowing the fuselage to remain intact while the wings were sliced open by eight cement ‘rhino horns’ in the runway.
The left wing touched the ground first, causing the plane to skid sideways on the runway. Because the aircraft landed off-centre, one of the horns sliced through the plane’s right side engine and continued into the fuselage, causing fuel to enter the cabin.
Cutting through the engine generated enough heat to ignite the fuel, this created an impressive fireball which took over an hour to extinguish.
As well as a great (if a bit scary) set of images, researchers also managed to capture video from a number of different viewpoints, including from the cockpit, and the plane’s tail. It’s definitely not for those with a fear of flying:
NASA didn’t do it just because they had a spare Boeing 720 and a GoPro laying around, the primary object of the experiment was to investigate an additive that retards fuel flammability.
The additive was called FM-9, and when combined with Jet-A fuel creates an anti-misting kerosene (AMK). AMK demonstrated flame-inhabiting properties in the lab, but the FAA wanted to experiment with them in a real-world test.
Because things like this don’t happen very often, the plane was also packed full of new safety innovations ready for testing. These included updated seat belt designs, flight-data recorders, fireproof cabin materials and burn-resistant windows.
The plane was also fitted with structural load measuring equipment, including a horde of instrumented crash dummies in the passenger seats.
The final conclusion on AMK was that it does not provide a sufficient enough benefit in the event of a crash; the FAA concluded that 25 per cent of the passengers would have survived. The organisation estimates passengers in the forward cabin would have had just five seconds before smoke obstruction; passengers in the rear had a leisurely 20 seconds.
A repeat experiment was held in 2012, when a television company bought a Boeing 727 and crashed it in the Mexican desert. This experiment was decidedly less scientific than the previous attempt, with the documentary film-makers examining where the best place to sit on a plane is in the event of a crash.
The show came to the conclusion that the safest location is where the plane hits last, which isn’t really a revelation. The documentary aired on Channel4 in the UK.