Post by "AlexH" on the Dupuy Institute's forum at: http://www.dupuyinstitute.org/ubb/Forum4/HTML/000067.html --------------- Rich, You paint a scenario that sounds like procuring 90mm guns would stop the US war effort! As you know, the US developed entirely new vehicles during the war, A 90mm afv could, and should, have been fielded in 1943. Lets take a look at the development history of various afvs: M3 Grant/Lee 13-Jun-40 Updated Requirements 11-Jul-40 Standardized as M3 26-Aug-40 Wooden Mockup shown at Aberdeen Proving Grounds 20-Dec-40 Production Drawings 905 Complete Apr-41 Joint Tank Planning Committee pushes for 2000 tanks per month by July 1941 Feb-41 Design Finished 13-Mar-41 First Pilot Finished 5-May-41 Pilot Tests at Aberdeen Proving Grounds begin Sep-41 Production of M3 in full swing at 4 manufacturers M4 Sherman 1-Feb-41 Design Initiated May-41 Mockup construction recommended 2-Sep-41 Aberdeen Pilot Completed 5-Sep-41 Design Standardized as M4 Feb-42 Production Starts Two things are important to keep in mind, the time from design to pilot, and the time from pilot to production. In the M3&M4 cases, these average out to roughly 7.5 and 5.5 respectively. Lets look at the design cycles for other American afvs: M6 22-May-40 Development Project Initiated 11-Jul-40 Project Approved 24-Oct-40 OCM 1600 (Revised Layout) 22-Nov-40 Revised Layout Approved Aug-40 Contract for M6 Prototype, Baldwin Locomotive Works Aug-40 Pilot Tank Assembled Aug-41 Testing at Baldwin Locomotive Works 8-Dec-41 Tank Officially Presented to the Ordnance Department 13-Apr-42 Standardization of the M6, M6A1 10-Aug-42 Classified as "Limited Procurement Type" 7-Dec-42 Cancellation to the M6 Program 16-Jan-43 First Production M6 Shipped 17-Mar-43 M6 Upgunned to 90mm 14-Aug-44 Conversion of 15 M6 to 105mm gun (15 November 1944 delivery date) T29/T30/T34 14-Sep-44 Development and Manufacture Recommended (4 prototypes) 1-Mar-45 1200 Unit Procurement recommended 12-Apr-45 Procurement Aproved (1,152) 11-Aug-45 Procurement Cancelled (1.5 vehicles manufactured) (War ends, project downgraded) Oct-47 First T29 arrives at Aberdeen Proving Grounds Apr-48 Additional T29 arrives at Aberdeen Proving Grounds May-48 Additional T29 arrives at Aberdeen Proving Grounds T32 7-Dec-44 Army Ground Forces Recommends Development of a "Heavier Pershing" 8-Feb-45 Recommends Construction of 4 Pilots 10-Apr-45 Mock-up almost complete, 80% of Drawings Released (War ends, project downgraded) 15-Jan-46 Pilots 1 & 2 Delivered (2nd on 19/1/46) Time to pilot averages out to about 8-9 months - for an entirely new vehicle. Please note that the previous afvs were all heavy tank projects in the 50-80 ton range. The average for the four projects analyzed is 8 months from design to prototype. Now, lets examine the following: "M Plus" 8-Dec-41 Chief of Ordnance orders design study of improved Sherman 13-Mar-42 Aberdeen submits layout drawings Aug-42 Armament Drawings Since December of '41, the Chief of Ordnance had ordered the development of an M4 "improved" tank. IF, priority had been given to this project, and it had progressed along at the same pace as other wartime projects we have: 8 months development + 5 months to series production = 13 months. Counting from December of 41, produces a 90mm afv in the early 1943 timeline. Counting from a more realistic date, say October of 42 (when the feasibility of mounting a 90mm gun in the Sherman was reported by Aberdeen), generates the desired afv by late in '43. Now, let's see about upgunning: Upgunning 1-Aug-42 76mm M4 Test Fires at Aberdeen 17-Aug-42 76mm Sherman designated Substitute Standard 23-Oct-42 Drawings show rolled armored turret mounting 76mm gun for Sherman 2-Feb-43 Pilot Production 76mm Shermans arrive at Aberdeen 5-Apr-43 Final Report Submitted 3-May-43 Recommendation for T20 76mm Turret mounting on Sherman hulls 17-Aug-43 Firing Tests and Report from Armored Board recommends acceptance and immediate production The upgunning process went through two complete cycles, each cycle took aprox. 3 months, plus a further 3 months for acceptance trials. What about a 90mm upgrade? 31-Oct-42 Ballistics Research Laboratory at Aberdeen reports feasibility of 90mm mounting on a Sherman turret Nov-43 Armored Board requests 90mm guns be mounted in 1000 Shermans Jul-44 General Joseph Holly tasked by Eisenhower to expedite production and shipment of 90mm tanks and TDs. A similar, double, development cycle plus three months trial acceptance (all along the lines of the 76mm upgunning history), starting in October of '42, produces a 90mm armed Sherman by the Summer of '43. There is a 12 month gap between the Aberdeen report and the request from the Armored Board, and a further 8 months until the issue became so urgent General Holly is tasked with expediting the delivery of more powerful afvs. That 20 month gap - history demonstrates - was more than enough time to field a 90mm afv, not only by the Normandy invasion, but by sometime in the second half of 1943. Someone dropped the ball, and that someone was affiliated to the SLS.