The Air Force Research Laboratory (AFRL) has allocated the X-Plane designation X-55 to Lockheed Martin’s Advanced Composite Cargo Aircraft (ACCA) proof-of-concept demonstrator just a few weeks after awarding the manufacturer a Phase III contract covering a new series of flight tests.
Arguably the most important airlifter demonstrator since the YC-14 and YC-15 programs of the 1980s, and considered by most to be the first full-scale transport X-plane of its class to reach the flying stage since the LTV XC-142 tiltwing in 1964, the X-55 is expected to resume flight tests around January 2010.
The heavily modified aircraft retains the original wing, nose section and engines of the Dornier 328JET, but has a completely new fuselage and vertical tail made of advanced MTM45-1 composite materials fabricated using out-of-autoclave curing. Around 15 to 20 flights are expected to be conducted during the program which will continue the envelope expansion begun with the first flight in June this year.
(U.S. Air Force)
The X-55 allocation helps fill out a little more of the X-Plane listing with the exception of certain gaps. Working forwards from the X-40 Space Maneuver Vehicle, X-Plane watchers now have:
X-41. Common Aero Vehicle – hypersonic test vehicle role later subsumed by Falcon
X-42. Pop-Up Upper Stage, expendable liquid-fueled upper stage rocket
X-43. Scramjet demonstrator
X-44. Believed to be for un-built multi-axis, no-tail aircraft thrust vectoring demonstrator.
X-45/X-46 and X-47. All allocated to UCAV programs
X-48A/B/C. Blended wing body
X-49A. Piasecki Aircraft Speedhawk – compound helicopter
X-50. Dragonfly – canard rotor/wing demonstrator
X-51. WaveRider – scramjet demonstrator
X-52. Believed purposely not allocated
X-53. Active aeroelastic wing on modified F-18
X-54. NASA-Gulfstream supersonic demonstrator - not yet taken up
X-55. Formerly ACCA
There are a few potentials out there that could be down for the X-56 slot, one of them being the Air Force’s Reusable Booster System. The RBS, as many pointed out when we wrote about this earlier this year, is yet another reusable launch vehicle project – this one is aimed at a potential sub-scale X-plane demonstration in the 2017-2018 timeframe. But, unlike all those previous failed attempts – including apparently the X-42 – the signs are more optimistic this time. The requirement is arguably more urgent than ever, the technology is far more mature and, more embarrassingly, it may even have to wait in line for take-off behind a queue of space tourist flights. Now there’s impetus for you, surely!?