I think there was a much of Martin designation numbers were given after the
Model-491 but unknown or little known,for examples,the Model-744,796 and 797
was given to RB-57D series,and the last known designation to me the Model-845 RPV.
I've re-worked and updated that 1998 Glenn L. Martin Aviation Museum M- number list in the hope that this will make it more easily searchable. I've inserted Secret Projects links to specific projects (please PM any missing or added links).

Correction/additions welcome. I've left off the later Martin Marietta designations (eg: MMC-845A RPV for Compass Dwell program). I've assumed that these MMC- designations are not directly connected to the earlier M- numbers.

Some mysteries remain. Such as M- numbers for the following ...

Martin PM-3 twin-fuselage naval aircraft

Martin 'XBLR-4' 1935 very long-range bomber

Martin 100-pax flying boat

Martin "Mighty Midget" prone-pilot, twinjet attack aircraft

Martin B-57 transport derivative (2 x J79s, mock-up)

LARA (Bronco) Martin COIN http://www.secretprojects.co.uk/forum/index.php/topic,344.0.html
Martin M- Numbers

M-1-56 - Unassigned to aircraft
M-57 - MO-1 Navy observation a/c, 1923-1924
M-58-59 - Unassigned to aircraft
M-60 - M2O-1 Navy observation a/c, 1923
M-61-62 - Unassigned to aircraft
M-63 - Navy observation a/c, 1923
M-64 - [Project] monoplane glider
M-65 - [Project] forest patrol a/c
M-66 - NBL-2 (MNM-1) Navy night bomber/night mail, 1923
M-67 - N2M-2 Navy trainer, 1923
M-69 - [Project] Liberty mailplane
M-70 - "Commercial" night mailplanes (Model 66 conversions), 1924
M-71 - [Project] XO-4 Navy observation a/c, 2-seater
M-72 - [Project] Liberty mailplane
M-73 - T3M series, Navy multi-purpose a/c, 1927-1928
M-74 - T4M-1, Navy multi-purpose a/c, 1927-1928
M-75 - [Project] XLB-4 Army bomber
M-76 - [Project] undesignated Army bomber
M-77 - XT5M-1 Navy divebomber, 1929
M-78 - Unassigned to aircraft
M-79 - [Project] twin-engined commercial a/c
M-80 - [Project] Navy trainer
M-81 - [Project] Army high-speed bomber
M-82 - [Project] Navy Patrol Bomber (became Model 119 XP2M)
M-83 - [Project] XO2M-1 Navy observation fighter
M-84 - [Project] Commercial flying boat
M-85 - [Project] XO-27 Army observation
M-86-99 - Unassigned to aircraft
M-100-114 - Unassigned to aircraft
M-115 - [Project] touring plane, 2-pax, open cockpit
M-116 - [Project] sport coupe, 2-pax
M-117 - PM-1/PM-1B Patrol bomber (USN/Brasil respectively), 1930
M-118 - XT6M-1 Navy torpedo bomber, 1930
M-119 - XP2M Navy patrol flying boat (XP2M-1 3-engined, XP2M-2 2-engined), 1931
M-120 - P3M-1/P3M-2 Navy patrol flying boat, 3-engined, 1931
M-121 - [Project] Commercial flying boat, 3-engined (modified XP2M-1)
M-122 - PM-2 Navy patrol flying boat, 1931
M-123 - XB-907/XB-10 Army high-speed monoplane bomber, 1932-1933
M-124 - [Project] Army general-purpose bomber
M-125 - BM-1 Navy divebomber (modified XT5M-1), 1932
M-126 - [Project] Sesquiplane patrol flying boat, 1932
M-127 - [Project] XFM-1 Navy divebomber
M-128 - [Project] commercial flying boat, 4 diesel engines
M-129 - BM-2 Navy divebomber, 1932
M-130 - Ocean Transport/'Clipper' commercial flying boat, 4 x 950hp P&W Twin Wasp, 1935
M-131 - [Project] USAAC sea observation
M-132 - [Project] B2M-1 Navy divebomber
M-133 - [Project] 12-pax commercial transport
M-134 - [Project] twin-engined commercial flying boat (P3M-2 type)
M-135 - [Project] Navy bomber/scout (BM type)
M-136 - [Project] Navy long-range patrol flying boat
M-137 - [Project] Army ground attack
M-138 - [Project] Navy amphibian scout
M-139 - Army high-speed monoplane bomber: YB-10/YB-10A (Model 139As), 1934; YB-12/YB-12A/YB-14 (Model 139Bs), 1934-1935; B-13 [Project]; B-10B, 1934-1936; A-15 attack bomber, 1937; O-45 observation bomber, 1937.
M-139W- Export high-speed monoplane bomber: 139WA Argentian demo, 1937; 139WAA Argentine Army, 1937; 139WAN Argentine Navy, 1937; 139WC China, 1937; 139WC-2 China, 1937; 139WH Netherlands, 1937; 139WH-2 Netherlands, 1938; 139WH-3 Netherlands, 1938; 139WH-3A Netherlands, 1938; 139WR Russia, 1936; 139WSM Siam, 1937; 139WSM-2 Siam, 1937; 139WT Turkey, 1937
M-140 - [Project] Army bomber
M-141 - [Project] Navy flying boat
M-142 - [Project] Navy catamaran flying boat
M-143 - [Project] Pan Am 20-pax 'Streamliner'
M-144 - [Project] Navy torpedo bomber
M-145 - [Project] XB-16/XB-16A, initial layout 4 x tractor props, 1935 layout twin-boom with 4 x tractor and 2 x pusher props (later 2 x tractor and 2 x pusher props with barbettes in nose of outer nacelles).
M-146 - Army high-speed monoplane bomber, 2 x Wright Cyclones, 1935
M-147 - [Project] Navy monoplane flying boat, 4 engined
M-148 - [Project] Pan Am monoplane flying boat, 4 engined
M-149 - [Project] Export bomber
M-150 - [Project] 40-pax 'Streamliner' commercial flying boat
M-151 - [Project] Long-range bomber, twin-engined
M-152 - [Project] Commercial flying boat, 63000 lb
M-153 - [Project] Commercial flying boat, transatlantic, 100000 lb
M-154 - [Project] Pan Am flying boat, 54000 lb
M-155 - [Project] Pan Am flying boat, 55000 lb
M-156 - "Russian Clipper" four-engined ocean transport, Russia, 1938
M-157 - [Project] four-engined ocean transport
M-158 - [Project] TWA land trasnport a/c, 70000 lb
M-159 - [Project] Navy observation scout
M-160 - [Project] Navy 4-engined long-range patrol boat (M-160A, M-160B; engineering 1939)
M-161 - [Project] Army high-speed, twin-engined bomber
M-162 - Mariner; 162 XPMB-1/XPBM-1A/PBM-1/XPBM-2, 1939/1941; 162A 3/8 scale model, 1937; 162B PBM-3/XPBM-3E/PBM-3R, 1942; 162C PBM-3C/XPBM-3D/XPBM-3S, 1942; 162D PBM-3D, 1944; 162E PBM-4 [Project]; 162F XPBM-5/PBM-5, 1944; 162G XPBM-5A/PBM-5A 1945; 162Com export commerical Mariner [Project]; 162W 45000 lb Mariner [Project]
M-163 - [Project] 4-engined long-range commercial ocean transport
M-164 - [Project] 4-engine 27,500 lb bomber
M-165 - [Project] twin-engined bomber
M-166 - [Project] production M-139WH-3 export bomber
M-167 - Maryland; XA-22 twin-engined attack bomber, 1939; French export 167-A3 (M-167-F1, -F2, -F3, 1939; 167-B3 (Maryland Mk I), 167-B4 (Maryland Mk II) 1940/1941, 167-H1, 'H2 (Dutch, cancelled)
M-168 - [Project] Navy high-speed, single-seat Navy fighter
M-169 - [Project] twin-engine heavy attack bomber
M-170 - Mars 4-engined flying boat; M-170 prototype XPB2M-1/transport conversion XPB2M-1R, 1942; M-170A JRM-1 cargo transport, 1946; 170B JRM-2 cargo transport, 1948/JRM-3 conversion, 1950; M-170C [Project] 165,000 lb commercial flying boat
M-171 - [Project] long-range, high-speed patrol bomber
M-172 - [Project] M-172A/172B export bomber
M-173 - [Project] M-173A 24-pax commercial transport, M-173B 27-pax commercial transport, M-173C Army twin-engined, high-speed bomber
M-174 - [Project] Army attack bomber
M-175 - [Project] Army attack bomber
M-176 - [Project] Army attack bomber
M-177 - [Project] Army attack bomber
M-178 - [Project] twin-engined bomber
M-179 - Marauder; M-179 B-26; M-179A B-26A/B-26A-1, 1942; M-179B B-26B, 'B-1, 'B-2, 'B-3, 'B-4, 'B-10, 'B-15, 'B-20, 'B-25, 'B-30, 'B-35, 'B-40, 'B-45, 'B-50, 'B-55, AT-23A; M-179C
B-26C-5, 'C-6, 'C-10, 'C-15, 'C-20, 'C-25, 'C-30, 'C-45, AT-23B; 179D XB-26D; M-179E B-26E; 179F B-26F-1, 'F-2, 'F-6; M-179G B-26G-1, 'G-5, 'G-10, 'G-11, 'G-15, 'G-20, 'G-21, 'G-25,
TB-26G-20, TB-26G-25
M-180 - [Project] Navy twin-engined, long-range patrol bomber
M-181 - [Project] Navy twin-engined, long-range patrol bomber
M-182 - [Project] XB-27 twin-engined supercharged bomber
M-183 - [Project] Navy twin-engined, long-range patrol bomber; M-183D medium-range patrol bomber
M-184 - [Project] Navy patrol utility (one or two engines)
M-185 - [Project] Navy patrol utility (one or two engines)
M-186 - [Project] Navy amphibian patrol utility (one or two engines)
M-187 - Baltimore; XA-23 [Project]; 187-F1 French reconnaissance bomber (cancelled); 187-B1
Baltimore Mk I, Mk II, Mk III; 187-B2 Baltimore Mk IIIA, 187-B3 Baltimore Mk IV, Mk V; 187-B4 Baltimore Mk VI (cancelled); 187-H1 Dutch reconnaissance bomber (cancelled)
M-188 - [Project] Model 186 modified for export
M-189 - [Project] XB-33 twin-engined, high altitude medium bomber
M-190 - [Project] XB-33 four-engined high altitude medium bomber, B-33 (400 cancelled)
M-191 - [Project] twin-engined bomber
M-192 - [Project] twin-engined torpedo bomber
M-193 - [Project] 250,000 lb cargo transport (modified JRM)
M-194 - [Project] four-engined "Lone Ranger" heavy bomber
M-195 - [Project] twin-engined, high-speed medium bomber
M-196 - [Project] twin-engined, multi-purpose medium bomber; M196-1
M-197 - [Project] twin-engined medium bomber
M-198 - [Project] twin-engine, high-speed patrol bomber
M-199 - [Project] 145,000 lb cargo land transport (modified JRM)
M-200 - [Project] 100,000 lb four engine passenger transport
M-201 - [Project] twin-engined, high-speed bomber
M-202 - 2-O-2 twin-engined commercial transport, prototype; 202FL 2-O-2, Chile; 202NW, Northwest; 202LAV, Venezuela; 202A, Trans World; 202E, Eastern (cancelled) 1944 high-wing study http://www.secretprojects.co.uk/forum/index.php/topic,4539.0.html
M-203 - [Project] bomber, 4 x Allison V-3420, 196,000 lbs MTOW
M-204 - [Project] high-performance, low-altitude bomber
M-205 - B-35 Martin-built flying wing intercontinental bomber (cancelled)
M-206 - [Project] Navy twin-engined patrol bomber
M-207 - [Project] twin-engined fighter (?? XP-49/XP-50 competition ??)
M-208 - PBB-1 Ranger twin-engined patrol bomber (cancelled)
M-209 - [Project] four-engined, long-range bomber
M-210 - Mauler; M-210 XBTM-1; M-210A AM-1; M-210B AM-1Q; M-210C AM-2
M-211 - [Project] Navy land-based patrol plane
M-212 - [Project] twin-engined, long-range patrol boat
M-213 - [Project] light transport
M-214 - [Project] six-engined, long-range commercial transport
M-215 - [Project] twin-engined refrigerated cargo
M-216 - [Project] eight-engined 500,000 lb flying aircraft carrier
M-217 - [Project] Flying wing fighter
M-218 - [Project] Twin-jet, high-altitude fighter
M-219 - XP4M-1 Mercator USN patrol aircraft prototype, M-219A P4M-1, M-219B P4M-1Q
M-220 - [Project] Four engine/two jet Navy patrol bomber
M-221 - [Project] Twin-engined, 15,000 lb aircraft
M-222 - [Project] Twin-engined land transport
M-223 - XB-48 Experimental six jet medium bomber
M-224 - [Project] Twin-engined military transport (modified 2-O-2)
M-225 - [Project] Four-engined long range patrol bomber; M-225-1; M-225-2
M-226 - [Project] Four-engined patrol bomber
M-227 - [Project] High-performance jet dive bomber, Navy
M-228 - [Project] Twin-engined, 26-passenger commercial transport
- M-228: M-202 deriv., 2 x Wright R-1820 Cyclones, span 28.00 m
M-229 - [Project] Four-engined 150,000 lb transport (modified JRM Mars)
M-230 - [Project] Four-engined patrol boat
M-231 - [Project] Four-engined patrol land plane
M-232 - [Project] Twin-engined carrier based bomber
M-233 - [Unassigned -- possibly MX-771, XSSM-A-1, XB-61 Matador]
M-234 - XB-51 (XA-45) three-jet ground-support bomber
M-235 - [Project] High performance Navy fighter
M-236 - [Project] Heavy Air Force bomber (B-52 competition)
M-237 - XP5M-1 Marlin flying boat prototype; M-237A P5M-1, P5M-1S, P5M-1G, P5M-1T, P-5A, SP-5A, TP-5A, M-237B P5M-2, P5M-2S, P-5B, SP-5B; M-237V P5M-2G
M-238 - [Project] Anti-Submarine Warfare (ASW) aircraft, Navy
M-239 - [Project] Three-jet low-level attack, Army (modified XB-51)
M-240 - [Project] Four-engined heavy troop/cargo transport
M-241 - [Project] Twin-engined cargo transport
M-242 - [Project] Assault seaplane transport
M-243 - [Project] Four-jet medium bomber
M-244 - [Project] Two-place basic trainer, Army
M-245 - [Project] Two-place long-range special-attack monoplane, M-245-1 airplane component with droppable hull, M-245-2 airplane component with droppable launch gear, M-245-3 airplane component with retractable gear, M-245A alternate carrier-based plane
M-246 - [Project] Carrier-based jet (Allison T40) attack bomber, Navy (A2F/A-6 competition)
M-247 - [Project] Four-turboprop medium bomber (modified XB-48 for USAF XB-55 competition)
M248-250 - Unassigned to aircraft
M-251 - [Project] Four jet high performance bomber
M-252-253 - Unassigned to aircraft
M-254 - [Project] Antisubmarine warfare (ASW) seaplane, Navy
M-255 - [Project] CVE-105 Class carrier-based ASW aircraft (S2F/S-2 Tracker competition)
M-256-258 - Unassigned to aircraft
M-259 - [Project] Water-based version of Model XB-51
M-260 - Unassigned to aircraft
M-261 - [Project] Twin jet land based minelayer aircraft, Navy
M-262 - [Project] Single turboprop VTOL convoy fighter (XFY-1 Pogo/XFV-1 Salmon competitor) Navy, M-262P 766 scale version of Model 262, Navy
M-263 - [Project] Ground support attack aircraft, Air Force
M-264 - Unassigned to aircraft
M-265 - [Project] Flying infantry ship, Air Force [poss. prone-pilot "Mighty Midget"?]
M-266 - Unassigned to aircraft
M-267 - [Project] P5M-1 modification to ASW patrol seaplane, Navy
M-268 - [Project] Twin engine trainer, Air Force
M-269 - [Project] Medium bomber, Air Force
M-270 - XP5M-1, 15/1 length beam ratio to hull of XP5M-1
M-271 - P5M-2, uprated P5M-1, cancelled
M-272 - XB-57 Twin jet medium bomber, USAF, M-272A B-57A, RB-57A; M-272B 'Super Canberra' (cancelled), B-57B, EB-57B, JB-57B, NB-57B, RB-57B; M-272C B-57C, TB-57C, RB-57C, WB-57C, M-272D RB-57D-1, RB-57D-2, RB-57D-3, RB-57D-4, M-272E B-57E, EB-57E, JB-57E, NB-57E, RB-57E, TB-57E, M-272M B-57M (cancelled), M-272N EB-57D, M-272P RB-57F, WB-57F, M-272R RB-57A, EB-57A, NRB-57A, M-272S B-57 ejection seat, M-272T B-57G
M-273 - Unassigned to aircraft
M-274 - P5M-1 Marlin Twin engine air/sea rescue seaplane, Navy
M-275 - XP6M-1 Seamaster 'Fast Mine-Laying Maritime Patrol Flying Boat' prototypes; M-275A
YP6M-1 development aircraft; M275B P6M-2
M-276 - [Project] Fighter bomber, Air Force
M-277 - Unassigned to aircraft
M-278 - [Project] Swept-wing fighter-bomber, Air Force
M-279 - [Project] High-performance land-based mine-layer, Navy
M-280 - [Project] Land-based Anti-Submarine Warfare (ASW) aircraft, Navy
M-281 - [Project] Short-range bombing/reconnaissance aircraft, Air Force
M-282 - [Project] Advanced night intruder, Air Force
M-283 - [Project] Carrier based attack aircraft, Navy (?? A-4 Skyhawk competitor ??)
M-284 - [Project] ZELMAL, Zero Launch Mat Landing (carrier based)
M-285 - Unassigned to aircraft
M-286 - [Project] Strategic Air Command (SAC) bomber, Air Force, WS-110A competitor http://www.secretprojects.co.uk/forum/index.php/topic,2920.0/highlight,martin+model.html
M-287 - [Project] ZELMAL Zero Launch Mat Landing (F-84G), Air Force
M-288 - [Project] Fighter bomber, Air Force
M-289 - [Project] Night intruder, Air Force
M-290 - [Project] P5M-3, BLC version of P5M, redesignated P7M SubMaster
M-291 - [Project] Antisubmarine warfare (ASW) aircraft, Navy
M-292-293 - Unassigned to aircraft
M-294 - reconnaissance version of B-57B, RB-57D Group A (RB-57D Group B was M-744; RB-57D-1 Group D was M-796; and RB-57D-2 Group C was M-797)
M-295-296 - Unassigned to aircraft
M-297 - [Project] P5M-Y, water-based ASW intrusion patrol aircraft, Navy
M-298 - [Project] P5M-X , reconfigured P5M-2 for ASW, Navy
M-299 - [Project] Lightweight fighter
M-300-301 - Unassigned to aircraft
M-302 - [Project] Long-range interceptor, Air Force
NB: WS-302A was XB-68 trijet tactical bomber project
M-303 - 3-O-3, twin-engined commercial transport (pressurized cabin); M-303U 3-O-3 (United Airlines); M-303NW 3-O-3 (Northwest Airlines); M-303B 3-O-3 (Braniff Airways); 303PAG 3-O-3
(Pan Am/Grace), M-303T 3-O-3 (Transcontinental/Western)
M-304 - [Project] 3-O-3, cargo version
M-305 - [Project] 3-O-3, unsupercharged version
M-306 - [Project] twin-jet (GE TG-180) transport version of 3-O-3
M-307 - [Project] SeaMistress transport flying boat
- http://www.secretprojects.co.uk/forum/index.php/topic,6396.msg53141.html
M-308 - [Project] Long-range interceptor (alt. #1 for M-302 project), Air Force
M-309-312 - Unassigned to aircraft
M-313 - [Project] P7M Submaster, open ocean sonar seaplane, Navy (mock-up)
M-314 - [Project] Long range interceptor (alt. #2 for M-302 project), Air Force
M-315 - [Project] Fighter bomber (unconventional takeoff), Air Force
M-316 - Mach 3 dash Tactical Air Command (TAC) bomber, USAF Canceled (originally WS-302A, then XB-68), two-engined (J75)
http://www.up-ship.com/apr/v0n0.pdf or
three-engined (GE J79-GE-1),
M-317 - [Project] refuelling tanker version of P6M Seamaster, Navy
M-318 - [Project] Extended-Range Countersurveillance (ERCS) version of P6M Seamaster, Navy
M-319 - [Project] TAC interceptor/bomber, Air Force
M-320 - Unassigned to aircraft
M-321 - [Project] air/sea rescue version of P5M Marlin, Navy
M-322-325 - Unassigned to aircraft
M-326 - [Project] Utility target-towing version of B-57
M-327 - WS-107A-2, SM-68 (HGM/LGM-25) Titan ICBM, Air Force
M-328 - [Project] Fighter bomber, Air Force
M-329 - [Project] four-jet supersonic patrol flying boat
M-330 - Unassigned to aircraft
M-331 - [Project] ASP (Advanced Seaplane), nuclear powered derivative of P6M Seamaster
M-332 - Unassigned to aircraft
M-333 - [Project] Cargo transport, Air Force
M-334-336 - Unassigned to aircraft
M-337 - [Project] Seaplane water base study, Air Force
M-338-342 - Unassigned to aircraft
M-343 - [Project] Cargo transport, Army
M-344 - [Project] Long range interceptor (?? WS-202/F-108 competition ??)
M-345 - [Project] Attack aircraft, Navy
M-346 - [Project] Attack aircraft, Navy
M-347 - [Project] Land-based ASW aircraft, Navy
M-348-349 - Unassigned to aircraft
M-350 - [Project] Strategic Air Command (SAC) bomber, Air Force
M-351 - [Project] Tactical Air Command (TAC) bomber, Air Force
M-352-353 - Unassigned to aircraft
M-354 - [Project] Short-range hovering aircraft, Army
M-355-357 - Unassigned to aircraft
M358 - [Project] Supersonic attack bomber (similar to 329), Navy
M-359-362 - Unassigned to aircraft
M-363 - [Project] Four ton payload STOL transport, Army
M-364 - Unassigned to aircraft
M-365 - [Project] Rotoprop aircraft, Army
M-366 - Unassigned to aircraft
M-367 - [Project] ASW seaplane, Navy
M368-370 - Unassigned to aircraft
M-371 - [Project] STOL cargo transport, Army
M-372-376 - Unassigned to aircraft
M-377 - [Project] Nuclear-powered ASW seaplane study
M-378-379 - Unassigned to aircraft
M-380 - [Project] Advanced vertical takeoff & landing (VTOL) studies
M-381 - Unassigned to aircraft
M-382 - [Project] Electronic countermeasures (ECM) trainer
M-383-399 - Unassigned to aircraft
M-400-403 - Unassigned to aircraft
M-404P - 4-O-4 , twin-engined commercial transport (pressurized cabin); 404E 4-O-4 (Eastern Airlines); 404T 4-O-4 (TWA); 404C RM-1G, RM-1Z, VC-3A, C-3
M-405-417 - Unassigned to aircraft [M-410 - Apollo proposal - ?? unconfirmed ??]
M-418 - [Project] Seaplane test bed for FT-56 turboprop
M-419-428 - Unassigned to aircraft
M-429 - M-103, re-entry vehicle technology (RVT) studies, Martin-Bell Dyna Soar I alternate
M-430-449 - Unassigned to aircraft
M-450 - RC-135B modifications, Air Force
M-451-457 - Unassigned to aircraft
M-458 - M-103, advanced lifting body reentry test studies, Air Force [?? SV-5 series ??]
M-459-467 - Unassigned to aircraft
M-468 - [Project] F-106B modification, variable stabilizer trainer (VST), Air Force
M-469-471 - Unassigned to aircraft
M-472 - F-101 modifications, Air Force
M-473-474 - Unassigned to aircraft
M-475 - F-104B modifications, side stick control system, Air Force
M-476-478 - Unassigned to aircraft
M-479 - F-101B modifications for reconnaissance, Air National Guard
M-480 - Lockheed P2V Neptune; 480A accelerated prototype; 480B production aircraft, USN; 480C Air Force - all cancelled
M-481-482 - Unassigned to aircraft
M-483 - EC-135H (Silk Purse command post aircraft conversions)
M-484 - Unassigned to aircraft
M-485 - P-3A modifications (special ASW), Navy
M-486-488 - Unassigned to aircraft
M-489 - M-489A Rockwell B-1 structural mode control vane; M-489B B-1B vertical and horizontal stabilizer
M-490 - Unassigned to aircraft
M-491 - GE CF6-80 thrust reverser; M-491A CF6-80C1; M-491B CF6-80C2A, CF6-80C2B
Hi Nugo,

Both JF Baugher and the USAF museum list the Model 223 as the two XB-48 prototypes (contract W33-038 AC-13492).

Hi Apophenia!

I am talking about Model 233, rather than Model 223 ( XB-48 )
er, Model 203 is a bomber, four engines (Allison 3420s, just in case you are interested) 196.000 lbs MTOW. In this case the right identification is that from the list published in "Martin Aircraft" (Thompson publ. 1995) and not the later published on the Martin Museum sit.
Thanks Skybolt,

That sounds pretty definative since the compiler of that Martin projects list, Stan Piet, is also a co-author.

For the record:

Martin Aircraft, 1909-1960
John R. Breihan; Stan Piet; Roger S. Mason
ISBN: 9780913322031
Publisher: Narkiewicz/Thompson (Santa Ana, CA)
Publication Date: 1995
Martin Model 294 (RB.57D) Group A
Martin Model 744 (RB.57D) Group B
Martin Model 796 (RB.57D-1) Group D
Martin Model 797 (RB.57D-2) Group C
Apophenia said:
Some mysteries remain. Such as M- numbers for the following ...

Martin PM-3 twin-fuselage naval aircraft

This has since been proved to be a J.V. Martin model, not a Glenn Martin type.

Martin 'XBLR-4' 1935 very long-range bomber

Since the BLR series included Boeing's Model 294 as the XBLR-1 (redesignated as B-15) and the Douglas XBLR-2 (redesignated as B-19), it is safe to assume that the XBLR-4 was simply redesignated as B-16 before it was ever allocated, since it doesn't appear on official records I think.

Martin 100-pax flying boat

This project closely resembles Pan American's Clippers in its concept. Three flying-boats were developed by Martin for Pan Am circa 1935: the Models 152, 154 and 155. Unfortunately the picture's caption states it was to weigh about 125 tons... This means 125,000 kgs or over 260,000 lbs. A far cry from the projected 63,000 lbs, 54,000 lbs and 55,000 lbs, respectively... This is closer to the weight of Model 170 Mars. The six-engine configuration is unusual for Martin, and the only example I've found is a Model 214 conceived during the war and described as a "six engine long range commercial transport"...

Martin "Mighty Midget" prone-pilot, twinjet attack aircraft

As I said in another topic, the date of the design (1951) and the particular mission of that aircraft have led me to believe that this was the Martin 265, described as a "Flying infantry ship" for the Air Force.

Martin B-57 transport derivative (2 x J79s, mock-up)

In typical Martin fashion, this could be another Martin 272 (suffixes F to L are unaccounted for). Otherwise, possible candidates would be Models 333 and 343 (canceled cargo transports) or the Model 326, a "utility tow target version of B-57".

LARA (Bronco) Martin COIN http://www.secretprojects.co.uk/forum/index.php/topic,344.0.html

Now this one is a true mystery for which I do not have the slightest clue. Considering the date (1963) it would be logical if it had received a designation somewhere around numbers 435-445.
Hi Stargazer2006!

I think:
Model 345 and Model 346---competitor of the A2F/A-6 (period of 1956-1957 years),
because the firm was involved in two proposals (one proposal with turboprop engine and other with turbojet engine).
"The Grumman A2F (A-6) Intruder was the result of a February 1957 Navy request for proposals for a replacement for the Douglas AD Skyraider in both the Navy and the Marine Corps. The request was accompanied by Type Specification 149, which asked for a two-seat aircraft capable of performing in all-weather conditions. An ability to take off and land in short distances was required, as was a top speed of at least 500 knots and a mission radius of at least 300 nautical miles. The Type Specification did not specify how many engines were to be used, or, indeed, even the type of engines to be used. Presumably either jet- or turboprop-powered designs would be acceptable.

Eight aircraft manufactures (Boeing, Douglas, Bell, Lockheed, North American, Vought, Martin, and Grumman) submitted proposals by the deadline of August 17, 1957." ...

source: Grumman A2F-1/A-6A Intruder, (Last revised December 3, 2001)

One who spoke about the 11(1) proposals and the other about 12(2) proposals;

(2)Two proposals for the following companies: (me a note)
1) Boeing (Model 7?? and Model 7?? (I think))
2) Douglas (Model 715 and Model 7??)
3) Vought (Model V-416 and Model V-416 with turboprop engine(?) or ?)
4) Martin (Model 345 and Model 346 (I think))
The group of firms that reported on a project, includes:
1) Grumman G-128Q
2) Bell (Model D-?)
3) Lockheed (Model CL-3??)
4) North American (Model ?)
source: will clarify

Model 246---Carrier-based jet (Allison T40) attack bomber (A2F/A-6 competition) ???
a source?
(Model 247---Four turboprop medium bomber, modified from XB-48 for B-55 competition), period of (1947-1948 years)
Although no indication that any model numbers existed before #56, I have come across this:


Source: http://www.historicaircraft.org/Army-Air-Corps/pages/Martin-M12P.html

Considering the fact that the rest of this archive is pretty accurate, I don't think it's a typo.
This is from the Glenn L Martin Aviation Museum website's history of Glenn Martin aircraft:

"Each of the last three MB-1's was modified for a special mission. Model TA (for "Trans-Atlantic") was fitted with extra tanks holding 650 gallons of fuel for an possible transcontinental or transoceanic flight, but was destroyed on the ground in a windstorm in July 1919. Model CA was the "gun machine," used to test a 37-mm cannon and a 3-inch recoilless rifle. The final plane of the original ten, Model 12P, was fitted out as a 12-passenger transport."

I have another refernce that calls this aircraft the 'Limousine'. From my own data collection:
"The last in the series of Martin GMB aircraft was fitted as a transport aircraft with the intial designation GMP and later the designation T-1. All military equipment was removed and the top of the fuselage was raised with cabin windows and seats added. The cockpit was enclosed. The serial was 62951."

Hope this puts it all in perspective.
Yes it does, thanks. Actually I realize I already had the info about the last three MB-1s, but the last example was just designated plain "12P" in my list. Also I didn't know about the "GMP" designation, nor that this was the same as the T-1. So thanks a lot!
Picked from the Spangenberg Index, courtesy of RyanCrierie:

- Model 250 (no details but perhaps linked to XAAM-4 Oriole)
- Model 293 Air-to-Surface Weapons System
Continuing my series of one-page indexes of each U.S. manufacturer's model numbers, allow me to introduce my page on Martin:


I have tried my best to picture every design that I was aware of (excluding minor subtypes or modifications that did not result from Martin's work) but I am sure of course that some stuff is still missing, especially in the field of missiles and spacecraft.

Please feel free to comment or even criticize this index, which in time will result in a clickable version with separate files for each (when I'm retired, that is! LOL).

Rutan/Scaled has been done already. I'm also currently working on McDonnell, Curtiss and North American.
Orionblamblam said:
Where'd you get the SV-5J photo? I've only ever seen one halfway decent photo of that, and from a different angle.

From the web, that's for sure... But where from exactly? At this point I couldn't say.

I'm attaching here all three photos I have of the SV-5J (written as "SV5J" on the fuselage). Two are of the aircraft on its wheels, presumably during its test program. The third one shows it on static display, perched on a pole.


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  • SV5J USAFA.jpg
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Came across this previously unknown Martin "air car", the Martin Ectijet. Did it ever leave the drawing board?


  • Martin Ectijet (1961).jpg
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Model 57: U.S. Navy observation monoplane (and Martin's first monoplane design); 36 aircraft produced (1923-24).


  • 1923 - 0156 (Martin MO-1).pdf
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  • 1923 - 0155 (Martin MO-1).pdf
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  • Martin MO-1.pdf
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  • 57.jpg
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Model 60: U.S. Navy observation twin-float biplane; three built (1923).


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Model 63: U.S. Navy twin-float submarine scout, also known as the « Martin Submarine Plane »; six built (1923).


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  • 1923 - 0298 (The Martin M.S.1).pdf
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Model 66: U.S.A.A.C. XNBL-2 night bomber, cancelled; completed as the MNM-1 night mail aircraft for U.S. Postal Service, three built (1923).


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Model 67: U.S. Navy N2M-1 biplane trainer prototype, one built (1923).


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Model 69: three-purpose (recce/bombing/torpedo) biplane, developed from Curtiss CS-1 scout plane.
35 built as SC-1 in 1925, 40 more as SC-2 in 1926 (later redesignated as T2M-1).
Two SC-1s converted as XSC-6 and SC-6, respectively. No information as to the SC-3, SC-4 and SC-5 designations.


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  • Martin SC-1.pdf
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Model 70: "Commercial" biplane remodeled from Model 66 mail plane, notably with rounded wing tips; three conversions (1924).


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  • 70.jpg
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Model 73: U.S. Navy Three-purpose (recce/bombing/torpedo) aircraft; 24 built as T3M-1, and 100 more as T3M-2 (all in 1927).
Two converted to XT3M-3 and XT3M-4 in 1927 and 1928, respectively.


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  • T3M-2_floats.jpg
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  • XT3M-3.jpg
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Model 74: Three-purpose (recce/bombing/torpedo) aircraft, a refined development of T3M; one XT4M-1 prototype and 102 production examples built (1928).
Design sold to Great Lakes (TG-1).


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  • T4M_spec.pdf
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