CitationJet (Model 525) essentially an all-new design, the only carry-over being the Citation I's forward fuselage.[28] The 525 series models all feature a shorter cabin; Not a stand-up. CJ1 (Model 525) Improved version of the CitationJet[28] CJ1+ (Model 525) Improved version of the CJ1 with new engines, avionics, and FADEC[29][30] Citation M2 CJ1 with updated avionics and engines CJ2 (Model 525A) Stretched version of the CJ1.[28] CJ2+ (Model 525A) Improved version of the CJ2 with increased performance, improved avionics, and FADEC.[31] CJ3 (Model 525B) Extension of the CJ2.[32] CJ4 (Model 525C) An extension of the CJ3, with new Williams FJ44-4 engines and the moderately swept wing borrowed from the Sovereign.[33] The first flight of the CJ4 is slated for the first half of 2008 with customer deliveries to follow in 2010.[34] Model 526 A twin-seat tandem military trainer developed by Cessna from the CitationJet for the JPATS competition.[35]