On 10 July 1964, McDonnell workmen began taking the simulator apart to ship it to Houston, there to be set up to match Spacecraft 3. The second Gemini mission simulator was already at the Cape, although not yet updated for Gemini 3. That was supposed to have been done by mid-July, but it was not finished until October. Final checkout took the better part of a month, and the Gemini 3 crews could not begin flying simulations in Florida before 9 November.5
But no such hangup ever left the astronauts with time on their hands. On 10 and 11 May, all four were in St. Louis to review a mockup of the cockpit. In the months that followed, they kept a close eye on their ship, watching as it passed through its series of tests and inspections in the McDonnell plant. They also joined in the testing itself. During the second phase of systems tests in October and November, Grissom and Young spent more than 14 hours in the cockpit, 9 of them while the spacecraft was undergoing altitude chamber tests. Schirra and Stafford were not far behind, with 8 cockpit hours.6
During July and August, the four Gemini 3 pilots (and all their fellows) were in Dallas for a training program on the moving-base abort simulator created by Ling-Temco-Vought, Inc. This device projected the Gemini 3 launch profile in striking detail, complete with such cues as noise, vibration, and a wide range of motions that might be caused by one launch anomaly or another. The trainees also learned how to deal with any number of booster or spacecraft systems malfunctions.7
Throughout their training, the prospective spacemen also kept their more mundane flying skills intact. Each managed to average 25 hours a month in the cockpit of an Air Force jet. They also put in more than 200 hours apiece in innumerable briefings, three of them formal affairs that lasted two days each at Houston, St. Louis, and Cape Kennedy, the others an ongoing series of informal systems familiarizations that were part of each training activity. Periodic reviews of mission plans, physical examinations, fittings for flight suits, sessions on experiments to be carried on the spacecraft and on biomedical aspects of the mission, and any number of other operational matters helped fill the hours to overflowing.8
In October 1964, the Gemini 3 crews tackled still another aspect of training, practice in getting out of their spacecraft after it landed. The three-part program began with a review of egress procedures in the Gemini mockup at the McDonnell plant, then moved to the flotation tank at Ellington Air Force Base, just up the road from the Manned Spacecraft Center. The tank was a king-size swimming pool, where the crews rehearsed (both with and without space suits) climbing in and out of a boilerplate spacecraft that was either floating or submerged.9 Grissom and Young completed the third phase of this training in emergency egress from a floating spacecraft during February 1965.  They rode a boat out into the Gulf of Mexico, where a model spacecraft was dumped into the water. Then, fully suited, they went through the postlanding checklist and practiced getting out of the spacecraft and into their one-man life rafts. The crews also took refresher courses in parachute landing that month.10
During November and December 1964, the four crewmen spent part of their time in Johnsville, Pennsylvania, at the Naval Air Development Center, the site of a man-rated centrifuge run by the Aviation Medical Acceleration Laboratory. The first phase of centrifuge training had taken place in July and August 1963, when Gemini controls and displays had been evaluated and all the astronauts had been spun through acceleration profiles for launch and reentry. For pilots not yet assigned to a mission, the second phase simply provided more of the same. But for the crews of Gemini 3 and Gemini 4,** it was an important part of mission training. They worked in pressure suits, and the others trained in shirtsleeves. Grissom rode the centrifuge for 9˝ hours, Young for 11 hours; Schirra and Stafford spent only a little less time in the centrifuge than the prime crew.11
When the mission simulator at Cape Kennedy had been updated to match Spacecraft 3, both crews began working in it off and on for the next four months. During that time, Grissom put in more than 77 hours flying his mission on the ground, rehearsing every phase of his planned flight again and again, not only when everything went right, but also when something went wrong.*** Young put in even more time than Grissom, over 85 hours, in the Cape simulator. Schirra managed to get in 43 hours, Stafford 54.12 In January 1965, Grissom and his fellow crewmen were back in Dallas for more work on the abort simulator, this time focused on how best to deal with each type of booster or spacecraft malfunction. By the time this training was over, Grissom had run through 225 aborts and Young 154; Schirra and Stafford each totaled only slightly less than Young.13
When Spacecraft 3 arrived at complex 19, the crewmen resumed their active role in spacecraft testing. Sandwiching this exercise between trips to Houston for egress and parachute training, Grissom and Young still managed to spend almost 19 hours in the cockpit, beginning with the premate flight test on 14 February and ending with the final  simulated flight on 18 March. Schirra and Stafford got in more than 14 hours of cockpit time. Altogether, the prime crew had logged 33 hours in their spacecraft before the final launch countdown began, and the backup crew had spent 22 hours.14
Nine months of grueling work were ready to pay off. By February 1965, Grissom was sure that "We're ready to go." NASA agreed. Rumors already put Gemini's first manned flight earlier than the officially announced April or May. And NASA Administrator James Webb, speaking at Nebraska Wesleyan University in Lincoln, hinted that the launch might come in late March.15 The men were ready, and the machines very nearly so.
* In January 1963, shortly after the second group of astronauts was selected, the pilots were given specialty assignments in the MSC programs. Grissom, one of the smaller astronauts, was assigned to the Gemini spacecraft. Because of this and his Mercury experience, he was very close to the McDonnell engineers and technicians - so close, in fact that the cockpits of the first three spacecraft were designed around him, giving him the best view of the instrument panel and out the window. The spacecraft was familiarly dubbed the "GUSMOBILE." Although Young was only two inches taller, his seat had to be compressed so he could fit into it. Stafford had to have adjustments made on both the seat and hatch to accommodate his six-foot frame. By July 1963, the program office had discovered that 14 of the 16 astronauts could not be fitted into the cabin as designed, and all later cockpits had to be modified.
** On 29 July 1964, James A McDivitt and Edward H. White II had been introduced to the press as the prime crew for Gemini 4. Frank Borman and James Lovell were announced as the backup crew.
*** The following figures suggest how thoroughly NASA tried to prepare a pilot for his mission. Grissom flew 20 normal and 46 aborted launches; 13 normal speed, 5 overspeed, and 4 underspeed insertions into orbit; 8 platform alignments; 9 runthroughs of the flight plan; 107 retrofires; and 64 reentries. He experienced 51 simulated failures of the booster and 211 systems malfunctions; 57 sequential, 34 electrical and communications, 17 attitude control and maneuver electronics, 30 orbital attitude and maneuver, 16 reentry control, 36 guidance and control, and 21 environmental control.
4 "Gemini Program Mission Report, GT-3, Gemini 3," MSC-G-R-65-2, April 1965, pp. 7-7, -45; "GT-3 Crew Selection," p. 6; memo, Harold I. Johnson to dist., "Preliminary description of simulators and training equipment expected to be used in Project Gemini," 5 March 1962, with enclosures; TWX, Charles W. Mathews to McDonnell, Attn: Walter F. Burke, GP-54718, 11 May 1964; MSC News Release No. 63-13, 26 Jan. 1963; "Abstract of Meeting on Crew/Hatch Clearance, July 30-31, 1963," 8 Aug. 1963; André J. Meyer, Jr., notes on GPO staff meeting, 6 Aug. 1963, p. 3; Raymond L. Zavasky, recorder, "Minutes of Senior Staff Meeting, August 16, 1963," p. 4; TWXs, Mathews to Burke, GPO-54046-A, 12 Aug., and GPO-54094-A, 20 Aug. 1963; MSC Consolidated Activity Report for Office of the Dir., Manned Space Flight, 21 July - 17 Aug. 1963, p. 23; Project Gemini Quarterly Status Report No. 7, for period ending 30 Nov. 1963, p. 5; memo, Peter J. Vorzimmer, "Memorandum on the Czernini Project History," [June 1967]; TWX, Mathews to Burke, GP-7049, 8 April 1965.
5 Mathews, activity reports: 31 May-2 June, p. 1, 4-10 Oct., p. 1, and 18 Oct. - 27 Nov. 1964, pp. 3-4; MSC Consolidated Activity Report for Office of the Assoc. Adm., Manned Space Flight, 21 June - 18 July 1964, p. 17.
6 TWX, Mathews to McDonnell, Attn: Burke, GP-54686, 28 April 1964; "GT-3 Mission Report," pp. 7-7, -45; MSC Weekly Activity Report for Office of the Assoc. Adm., 15-21 Nov. 1964, p. 1.
7 Consolidated Activity Report,17 May20 June 1964, p. 30; Zavasky, "Minutes of Senior Staff Meeting, June 19, 1964," p.3; Quarterly Status Report No. 10, for period ending 31 August 1964, p. 56.
8 "GT-3 Mission Report," pp.7-9, -44; Consolidated Activity Report 23 Aug. - 19 Sept. 1964, p. 50.
9 TWX, Wilbur H. Gray to GPO, "Gemini Weekly Activity Report No. 80," 713-488-0454, 25 Aug. 1964; Paul T. Chaput, "Crew Egress Procedures Developed during the Qualification Test Program for the Gemini Spacecraft At-Sea Operations," NASA Program Gemini working paper No. 5015, 26 Aug. 1964; "GT-3 Mission Report," pp. 7-8, -44; Consolidated Activity Report, 20 Sept. - 17 Oct. 1964, p. 32.
10 "GT-3 Mission Report," pp. 7-8, -44; "GT-3 Prime Crew Train at Sea," MSC Space News Roundup, 3 March 1965; "GT-3 Crews Perform Parachute and Egress Training," MSC Space News Roundup, 17 Feb. 1965.
11 Quarterly Status Report No.6, for period ending 31 Aug. 1963, pp. 77-78; "GT-3 Mission Report," pp. 7-8, -44; "News Conference, GT-4 Crew Selection," 29 July 1964; Consolidated Activity Reports, 18 Oct. - 30 Nov., p. 28, and December 1964, p. 25.
12 Mathews, activity report, 18 Oct-27 Nov 1964, pp. 2-3; TWX, Mathews to SSD, Attn: Richard C. Dineen, GV-52670, 13 Jan. 1965; "GT-3 Mission Report," pp. 7-7, -8, -45.
13 Consolidated Activity Report, January 1965, p. 16; "GT-3 Mission Report," pp. 7-8, -44.
14 "GT-3 Mission Report," pp. 7-7, -43, -44, 12-21.
15 "Astronauts Ready Now," The Kansas City Times, 5 Feb. 1965; Ellis Rail, "Gemini Shot May Come in March," Evening World-Herald, Lincoln, Neb., 5 Feb. 1965.