While it’s hard to argue with photographic evidence (well, then again, on second thought maybe not…), here are some quotes from fairly official documents that corroborate the liquid core stage air start:
Source: S. J. Gizinski III, D. B. Herrington, Martin Marietta Commercial Titan, Inc., Denver, Colorado: Titan III: Commercial Access to Space, AIAA-88-2611 (renumbered to AIAA-88-3476)
“Stage 0, comprised of two SRMs, provides the sole lift-off thrust for the commercial Titan.”
Source: S. Isakowitz, Martin Marietta Commercial Titan, Inc., Denver, Colorado: The Commercial Evolution of the Titan Program, AIAA-88-3119
“Each SRM, built by United Technologies Chemical Systems division, consists of 5 1/2 segments, provides 1.4 million pounds of thrust, and burns for 108 seconds for the initial boost. The liquid engine core vehicle consists of two stages for sequential boost after SRM burnout.”
Source: Patrick S. Bremner, Martin Marietta Space Launch Systems, Denver, Colorado: Titan III Geosynchronous Launch Vehicle Capabilities, AIAA-92-1803-CP
“Stage 0 consists of twin 10 foot diameter 5 112 segment solid-propellant rocket motors. The solid rocket motors (provided by Chemical System Division) provide the Titan Ill lift-off thrust and control with an average thrust of 2.8 M pounds, a specific impulse of 271.6 seconds, and nominal burn time of 1 16 seconds.”
Table 1, Titan III T Mission Sequence of Events, on page 11 shows Stage 1 ignition at 1 minute 49.5 seconds after SRM ignition and 8.4 seconds before Stage 0/1 separation.
Source: Virginia L. Hall, Martin Marietta Space Launch Systems, Denver, Colorado: Titan III Launch Vehicle Capabilities to Non-Geostationary Orbits, AIAA-92-1881-CP
“The lower segment of the core vehicle is Stage I, the upper segment is Stage II, and the SRMs are Stage 0. Initial lift-off and boost is provided by Stage 0 only, while Stage I and II complete the ascent to orbit.”
The Mission Event Table on page 582 shows Stage 1 ignition at 1 minute 48 seconds after SRM ignition and 8 seconds before SRM jettison.
Table 2, Sequence of Events for an IPO Mission, on page 583 shows Stage 1 ignition at 1 minute 48.8 seconds after SRM ignition and 8.4 seconds before SRM jettison.
Source: NASA TM X-71692, TlTAN/CENTAUR T/C-1 Post Flight Evaluation Report, Lewis Research Center, Cleveland, Ohio, April 1975
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19750013258_1975013258.pdf
“Launch is from Complex 41 at Cape Kennedy, Florida with ignition of the Titan Solid Rocket Motors (SRM's). These motors burn for about 120 seconds, and then are jettisoned. They provide an initial liftoff thrust of about 2.4 million pounds.
During the final seconds of the SRM's burn, the two liquid rocket engines are ignited on the Titan Core Stage I. (page IV-1)
“The Stage 0 phase of flight appeared to be near normal. The ignition of the Step I engines occurred at 114.5 seconds into the flight which was 0.4 seconds earlier than predicted. 12.1 seconds after Step I ignition (126.6 sec) the solid rocket motors (SRM's - Step 0) were jettisoned.” (page IV-2, see also Table IV-1 on page IV-4 and Figure IV-1a on page IV-6)
Source: NASA TM X-73475, TlTAN/CENTAUR D-IT TC-4 VIKING A Flight Data Report, Lewis Research Center, Cleveland, Ohio, July 1976
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19760021170_1976021170.pdf
“The flight profile for Titan Stage 0 phase of fl ight consisted basically of a short vertical rise with roll to the required flight azimuth, followed by an initial pitch/yaw maneuver and subsequent near zero total angle-of-attack. The required steering, referred to as wind biased steering, was determined on launch day and implemented by the Centaur DCU in an open loop mode. Propellant depletion of the Stage 0 engines activated the Titan Step 0 staging timer (1.5 g decreasing axial acceleration) which initiated Titan Stage I engine start, heat shield jettison/Stage I ignition and Titan Step O jettison. (page 4)
“The trajectory profile through SRM flight was near nominal with Stage I engine ignition occurring at 110.4 seconds into flight and SRM jettison occurring at 121.7 seconds.” (page 24, see also Table 4-1 on page 25)”
Source: National Aeronautics and Space Administration, Cassini Launch Press Kit, October 1997
http://www.jpl.nasa.gov/news/press_kits/cassini.pdf
“Launch begins with the ignition of the solid rocket motors, which burn for 2 minutes, 22 seconds to an altitude of approximately 66,000 meters (216,500 feet). The first stage of the liquid-fueled Titan ignites at 2 minutes, 12 seconds into flight at an altitude of about 58,000 meters (189,000 feet).” (page 36, see also Launch Events illustration on page 35)
Perhaps somebody with access to Titan User’s Guides can help sort out whether some versions did incorporate Stage I ground start.
Martin
