SOFIA! The Stratospheric Observatory For Infrared Astronomy was a NASA modified 747SP-21 that housed an infrared telescope. The aircraft, serial number 21441, was purchased by NASA in. It first flew as an observatory in 2010, and was retired in 2022. The scientific contributions made by this aircraft and those who developed, operated, and maintained it cannot be overstated. There are numerous resources and articles written about this remarkable aircraft and I encourage you to read more about it and its achievements. We’ve linked some of these articles below.
SOFIA flew its long hour missions at night at altitudes up to 45,000 ft, putting it (and its 8.2 ft telescope) above 99% of the IR-blocking atmosphere. The telescope itself was housed in a bay just forward of the tail. This bay was isolated from the forward, pressurized fuselage where the crew was housed. This bay featured a retractable door that was opened in flight to give the telescope an unobstructed view of the night sky.
The 747SP…
The 747SP (SP = Special Performance) was a shortened version of the classic 747 that was developed in the 1970s to compete with the L-1011 and DC-10, and to provide a platform that could fly ultra long-haul routes and maintain commonality with the 747. Only 45 SPs were produced despite Boeing’s 200 aircraft projections. One difference between the 747SP and the classic 747 was a larger rudder that featured tabs. This was due to the shortened fuselage of the SP and the rudder needing more effectiveness due to its shorter moment arm. The SPs were the only 747s to feature these rudder tabs. SOFIA was one of the last SPs to fly. Only 3 remain in active service.
These Trailing Edge tags are a special variant of the SOFIA Tag run (found on the home page). This 747SP rudder tab that was part of the SOFIA program. This rudder tab was part of a large lot of aircraft parts we purchased directly from NASA in early 2024, shortly after purchasing the QSRA. There were several other NASA aircraft represented with this lot, many of which will also be tagged (including its spare parts ship N4508H). This rudder tab, serial number 046, was delivered to NASA after receiving a new seal and NASA white paint (according to paperwork). This rudder tab was not on the aircraft when it was retired in 2022, and its flight history prior to 2015 was not included in the documentation. We do not know if/when this rudder tab was flown on SOFIA, but it’s connection with the program is well documented.
Trailing Edge tags were cut from the most aft part of the rudder tab and are double-sided white tags that are nearly a full inch thick! These “tags” are offered without a hole and come with a printed aluminum display. Like the Honeycomb tags, the displays also feature color-printed tag art.
Links to read more about SOFIA:
https://science.nasa.gov/mission/sofia/
https://www.space.com/sofia-observatory.html
https://www.747sp.com/sofia-747sp-will-end-operations/