The former Pan Am Clipper Lindbergh 747SP is being converted into a giant flying telescope platform in Palmdale, CA, and Waco, TX. It is carrying a 2.5 meter diameter, 20-ton Nasmyth reflector telescope that will be capable of imaging primarily in the infrared portion of the electromagnetic spectrum, as well as in the visible portion, for secondary tasks. The aircraft will fly 8 ~ 10 hour missions an average of three times a week through about the year 2030 (including down-time for maintenance/upgrades, relocation, etc.). The telescope has been installed and will perform observations through a 16 foot high, by 10 foot wide, opening in the upper left fuselage, just forward of the horizontal and vertical stabilizers. The aircraft has completed closed-door test flights with very favorable results, and will be undergoing eight months of computer, communications, and telescope instrument equipment installation and minor airframe modifications in Palmdale, CA, at the former Rockwell International / North American Aircraft B-1B Production Plant 40, adjacent to U.S. Air Force Plant 42, and its two 12,000-foot runways. In the Fall of 2008, SOFIA will begin a series of about 12 open-door flight tests to ensure that the aircraft can fly safely with the doors open various amounts, over a range of airspeeds and altitudes from about 38,000 to 45,000 feet MSL. By the Spring of 2009, SOFIA will begin limited "early science" missions while additional flight and systems tests are completed, and will begin full scientific missions in 2010. Instrument development will continue through at least 2014, when at least 20 different instrument packages will be available, with at least six installed aboard the aircraft on any given flight (instruments will be able to be installed and removed in a few hours between flights, as needed). The telescope is mounted in an oil-filled spherical bearing that allows it to roll from 15 to 75 degrees above the horizon, and three degrees fore-and-aft from the aircraft centerline, so that it is effectively decoupled from aircraft movements in calm to mildly-turbulent air. It will be able to remain bore-sighted on an astronomical target with an angle the size of a dime at a distance of over ten miles.
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View of the Mother of All Junction Boxes, mounted overhead, above the telescope assembly, through which 28 VDC, 115 VAC, and fiber optic data lines are routed - note the cables passing through the aft pressure bulkhead into the telescope cavity, where the telescope 2.5 meter diameter parabolic primary, 0.5 meter hyperbolic secondary, and two 0.2 meter wide tertiary infrared and visible light mirrors are located within their support frame - IMG_0293
Perspective view of the telescope sensor instrument support framing, in the context of how the telescope assembly extends down through the main deck into the former baggage compartment - you can get a much better appreciation of how large the telescope assembly really is - the pressure bulkhead that the telescope assembly is mounted in is well over 20 feet in diameter - IMG_0292
Another view of the telescope sensor instrument support framing and counterweights, along with the cabling that carries sensor data off the telescope assembly to the data processing, recording, and analysis computers and display/control consoles - IMG_0291
Close-up of the telescope sensor instrument support framing, where up to six instruments can be mounted at the focal points for infrared and/or visible light collected by the reflector telescope - note the counterweights bolted around the periphery, which have to be swapped in/out with their corresponding instrument assemblies - IMG_0287
View of the open overhead framing (note the flight control system cables passing through lightening holes in the frames, that are connected to hydraulic valves through "bell crank" levers, for moving the ailerons, elevators, and rudder), some of the operator consoles (none of which are populated with equipment, yet), and the aft pressure bulkhead, through which the telescope assembly passes, and is supported by, a one-meter diameter spherical bearing that is accurate to within one micron of radius - IMG_0286
The overhead framing that used to support the overhead bins along the centerline of the former economy section - the supports have been retained because they also support the emergency oxygen supply lines, seen here as the stainless steel tubing with the green labeling and fixtures - military transport aircrew-style full-face oxygen masks are provided at each crew member's seat console position - IMG_0289
Excitation track power distribution panel equipment rack in the operations area on the main deck that routes power to subsystems used to control movement of the telescope assembly - IMG_0283
View along the port (left) side of the fuselage, including the expanded "waistline" where the telescope cavity is, and the outer cavity door (OCD) system, covering a 10 foot wide, by 16 foot high, opening through the aft (rearward) portion of the fuselage - IMG_0274
"The nose knows!", as Jimmy Durante used to say. Even for this aircraft, originally delivered to Pan Am on 6 May 1977, the level of technology in that nose is still impressive today - heck, the first test pilot for SOFIA, after its extensive modifications, was a NASA astronaut! - IMG_0267
The SOFIA aircraft has been upgraded with four of the latest-and-greatest General Electric 72,000-pound thrust CF6-80E1 turbofan engines, since the aircraft will be flying through at least the year 2030, and the newest engines will more than pay for themselves in fuel/thrust efficiency savings, especially given the price of oil these days, and almost certainly the future (a 747 burns around 3400 gallons of Jet-A fuel per hour at cruise altitude) - IMG_0322
Even after three hours, the line of visitors snaked from the Moffett Federal Airfield operations building, unabated from earlier in the afternoon, until well after evening civil twilight (aka "dark" to non-aviators) - IMG_0318
The empennage ("tail feathers") of the SOFIA aircraft - being able to wander around a 747 on the tarmac is not something I've gotten to do before (the Transportation Security Agency really gets upset if you try that at an airport, especially since 9/11!) - definitely something every aviation buff should put on their "bucket list" - IMG_0316
Another view of the telescope cavity outer door - it can't be opened on the ground, or in flight, because the drive system components haven't been installed, yet - that will be done during the equipment installation period that will occur from late January through September 2008, at the SOFIA aircraft servicing facility in Palmdale, in a 200,000+ square foot hangar at what used to be the North American Aircraft Plant 42, adjacent to the U.S. Air Force's Plant 40, and two 12,000-foot runways - IMG_0315
Close-up view of the telescope cavity outer door, which measures about 10 feet wide by 16 feet high - this allows the telescope to roll between 15 and 75 degrees around the aircraft's centerline - there is also an inner aperture door that limits the exposure of the telescope to air moving past at up to Mach 0.92 at altitudes between - IMG_0314
Side view of the amazing 747SP main landing gear truck - smaller aircraft pilots, who pass beneath a 747 with its landing gear extended, call it a "Goodyear overcast" because of the huge amount of rubber that's going by - a 747 with its gear retracted is just a "Boeing overcast"