this could not account for the entire problem which instead had more to do with engine alignment. Acceptance data from the engine supplier (Rocketdyne) showed that a group of 81 engines had an average roll movement in the same direction of approximately the same magnitude as that experienced in flight. Although the acceptance test-stand and flight-experience data on individual engines did not correlate, it was determined that offsetting the alignment of the booster engines could counteract this roll motion and minimize the roll tendency at liftoff. After Schirra's Mercury flight did experience momentary roll problems early in the launch, the change was incorporated into Gordon Cooper's booster on MA-9. Launches Nine LV-3Bs were launched, two on uncrewed suborbital test flights, three on uncrewed orbital test flights, and four with crewed Mercury spacecraft. Atlas LV-3B launches were conducted from Launch Complex 14 at Cape Canaveral Air Force Station, Florida. It first flew on 29 July 1960, conducting the suborbital Mercury-Atlas 1 test flight. The rocket suffered a structural failure shortly after launch, and as a result failed to place the spacecraft onto its intended trajectory. In addition to the maiden flight, the first orbital launch, Mercury-Atlas 3 also failed. This failure was due to a problem with the guidance system failing to execute pitch and roll commands, necessitating that the Range Safety Officer destroy the vehicle. The spacecraft separated by means of its launch escape system and was recovered from the launch pad. A further series of Mercury launches was planned, which would have used additional LV-3Bs; however these flights were canceled after the success of the initial Mercury missions. The last LV-3B launch was conducted on 15 May 1963, for the launch of Mercury-Atlas 9. NASA originally planned to use leftover LV-3B vehicles to launch Gemini-Agena Target Vehicles, however an increase in funding during 1964 meant that the agency could afford to buy brand-new Atlas SLV-3 vehicles instead, so the idea was scrapped. Mercury-Atlas vehicles built and eventual disposition 10D—Launched Big Joe 9/9/59 20D—Backup vehicle for Big Joe. Reassigned to Atlas-Able program and launched 11/26/59. 50D—Launched Mercury-Atlas 1 7/29/60 67D—Launched Mercury-Atlas 2 2/21/61 77D—Original launch vehicle for Mercury-Atlas 3, replaced by Atlas 100D after postflight findings from Mercury-Atlas 1 88D—Launched Mercury-Atlas 4 9/13/61 93D—Launched Mercury-Atlas 5 11/29/61 100D—Launched Mercury-Atlas 3 4/25/61 103D—Cancelled 107D—Launched Aurora 7 (Mercury-Atlas 7) 5/24/62 109D—Launched Friendship 7 (Mercury-Atlas 6) 2/21/62 113D—Launched Sigma 7 (Mercury-Atlas 8) 10/3/62