Sikorsky models and designations

From Aero Digest 1926,

what was this ?.
 

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hesham said:
From Aero Digest 1926,

what was this ?.
Click to expand...
I shared this one elsewhere on the forum a few years ago, it's the Airco Messenger.
It was a smaller, four-seat version of the S-34 with two 120hp Super-Rhône engines and a simplified retractable gear. It was designed by Igor Sikorsky for the Aircraft Corp. of America (Airco), advertised in 1926, but not built.
 

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By the way, Airco was to act as selling agents for Sikorsky Manufacturing Corp., but the deal fell through.
Since the Airco "Messenger" was not pursued by Sikorsky, it didn't get an "S-" designation.
The Airco "Amphibian", of course, became the S-34.
 

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hesham said:
The S-94
Click to expand...
Nice!

S-98: Advanced Commercial Rotorcraft
Source: https://www.linkedin.com/in/michael-devita-29275513/

S-90: mentioned in RAND report but possibly a typo.
Most of the key components of the CH-53X have been demonstrated, or are in production, including the engine (V-22), rotor and blades (S-90), and transmission (MI-26).
Click to expand...

"S-96": several sites use that designation for VIP Helibus helicopters used by oil and gas companies transporting workers between locations, but it seems these are just typos for S-92.
 
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Got another one, although it's only hinted at in the fake registration:

S-104: HEX Tilt-wing two-rotor Hybrid Electric Demonstrator
 

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Stargazer said:
Nice!

S-98: Advanced Commercial Rotorcraft
Source: https://www.linkedin.com/in/michael-devita-29275513/

S-90: mentioned in RAND report but possibly a typo.


"S-96": several sites use that designation for VIP Helibus helicopters used by oil and gas companies transporting workers between locations, but it seems these are just typos for S-92.
Click to expand...
Is there a picture or a drawing of the S.98?
 
I'm surprised to have found a mysterious Sikorsky aircraft type that I had never noticed before in the FAA listings...

Sikorsky Aircraft Corp. SZ 338B
  • N382SB, MSN 0001
    Certificate Issue Date Oct 31, 2013
    Mode S Code (base 8 / oct) 51062112
    Mode S Code (base 16 / hex) A4644A
    Cancel Date 03/13/2018
    Reason For Cancellation Expiration
    Export To None
    Type Registration Corporation

  • N385SB, MSN 0002
    Certificate Issue Date Nov 1, 2013
    Mode S Code (base 8 / oct) 51067557
    Mode S Code (base 16 / hex) A46F6F
    Cancel Date 03/13/2018
    Reason For Cancellation Expiration
    Export To None
    Type Registration Corporation
Click to expand...
Another online source gives a more detailed account, which clearly gives it as a fixed-wing aircraft!
  • Aircraft: SIKORSKY SZ 338B (Category: Land, Engines: 2, Seats: 2, Weight: Up to 12,499 Pounds), Engine: Turbo-shaft
    N-Number: 382SB, N382SB, N-382SB, Serial Number: 0001, Certificate Issue Date: 10/31/2013
    Registrant (Corporation): Sikorsky Aircraft Corp, C/O John Zottola Mail Stop S212a / 6900 Main St, Stratford, CT 06614
    Deregistered: Cancel Date: 03/13/2018

  • Aircraft: SIKORSKY SZ 338B (Category: Land, Engines: 2, Seats: 2, Weight: Up to 12,499 Pounds), Engine: Turbo-shaft
    N-Number: 385SB, N385SB, N-385SB, Serial Number: 0002, Certificate Issue Date: 11/01/2013
    Registrant (Corporation): Sikorsky Aircraft Corp, C/O John Zottola / 6900 Main St Msc S212a, Stratford, CT 06614
    Deregistered: Cancel Date: 03/13/2018
Click to expand...
Source: https://www.city-data.com/aircraft/air-Stratford-Connecticut.html

My first thought was that "SZ 338B" could be related to the S330/S333 helicopters. Yet it couldn't be the Firefly electric demonstrator, since it was a single-engine, single-seater... And why "SZ" when the other former Schweizer models used a simple "S" designations?
Then another detail caught my eye: the letters "SB" at the end of both registrations, as in "Sikorsky Boeing". Could these registrations have been reserved (and not used) for the SB-1 Defiant? All the details correspond: two turboshaft engines, two seats...
However, the site AviationDB, which gives even more detail, claims that the SZ 338B was a "Fixed wing multi engine type"...
although Sikorsky hasn't built fixed-wing aircraft for over 80 years!

My best bet is that these two aircraft were never completed, despite the regs being reserved for them, but that doesn't make them any less mysterious! Ideas, anyone?
 
Hi Stargazer,

please can you make a complete list to "S",hope to begin from S-1,as you did
in reply # 14 ?.
 
I have finally worked out what the mysterious "Sikorsky SZ 338B" was ! Since the former Schweizer SA 2-38B Shadowhawk (RU-38B Twin Condor), became the Sikorsky SA-38B, I had a hunch, that the former SA 3-38B could be it... and after looking specifically for that particular model, it turned out that I was right: Kevin Hritz, Senior Principal Electrical Engineer at Sierra Nevada, who worked from 2006 to 2012 for Sikorsky Aircraft as Senior Electrical/Avionics/Systems Engineer, posted a photo of [N382SB] on his profile (the only one I've ever seen), and designated it as the "Sikorsky (Schweizer) SA 3-38B MCSA ISR Aircraft, powered by PT6A-34 engines."

Sikorsky (Schweizer) SA 3-38B MCSA ISR Aircraft.jpg
Source: https://www.linkedin.com/posts/kevi...r-aircraft-activity-6389631563683889152-N8Tl/

More about the SA-338B:
The SA-338B Shadow Hawk aircraft is a two or three-seat, fixed gear, low wing, twin boom aircraft. The SA-338B aircraft is designed to fly slowly along a coastline at an altitude of about 1,500 to 2,000 feet. Its primary mission applications include border protection, counter drug activities, intelligence collection against regional instabilities, fisheries patrol, environmental monitoring, and search and rescue. Sikorsky is marketing the SA-338B to the United States Coast Guard and the Department of Homeland Security.
Click to expand...
Source: https://www.airframer.com/news_story.html?release=9750

It would appear (notably from the various comments on the LinkedIn page I mentioned further up) that assembly started in 2010 and that 150 hours or PT6A ground tests were performed, but that the project was abandoned before the aircraft could fly. Also it is more than likely that the second airframe was never completed and that the registration reserved [N385SB] was never actually used.
 
As requested, I'm doing a simplified version of my Sikorsky list here. By "simplified", I mean there will be no detailed account of quantities, production batches, registrations or construction numbers for the larger production models. For the time being, I'll tackle only the S-29 through S-51 types (the rest will be done eventually). Note that I have also included the prototypes and projects that didn't garner a proper "S-" designation.

  • S-29A.png S-29-A "Yorktown". Biplane passenger transport with two 400 hp Liberty 12 engines (1924) [2756, c/n 1]. Was modified in 1928 as movie prop in Howard Hughes's Hell's Angels and was destroyed on purpose there.
  • S-30.png S-30. Large all-metal fabric-covered mail carrier/10-passenger transport project with two Wright J-4 Whirlwind engines (1924). Not built.
  • S S-30-B.png -30-B. Torpedo-bomber floatplane derivative project with same engines (1925). Not built.
  • Biplane modifications. A Curtiss JN-4C [2456, c/n 4] and a Curtiss Oriole [3089, c/n 3] were fitted experimentally with Gluhareff-Sikorsky G-S-1 wings (1925).
  • S-31.png S-31-A. Four-place trainer/photo biplane with 200 hp Wright J-4 Whirlwind engine, flown as a racer (1925) [no registration, possibly c/n 2].
  • S-31-PH. Same aircraft sold to Fairchild for aerial photography work (1925).
  • S-31-W. Same aircraft fitted with rear gunner position (circa 1926). Sold to Argentina through the Fairchild Flying Corp.
  • S-31-M. Planned mail/express variant, not built (1925).
  • S-31-P. Planned passenger taxi-plane variant with pilot in front and four-passenger semi-closed cabin in rear (1925).
  • S-32.png S-32. Four-seat transport biplane with a 400 hp Liberty 12 engine, built for Ancol, a subsidiary of Standard Oil (1926) [no registration, c/n 1].
  • S-33.png S-33 MESSENGER. Biplane racer powered by 60 hp Wright Gale, for NY races (1926) [no registration].
  • S-33A MESSENGER. Two-seat version (1927). NOTE: the Wright Gale engine was the former Lawrance L-3 type.
  • "AIRCO" SUPER-SPORT MESSENGER. Same type as marketed with more powerful 120 hp Super-Rhône engine by Airco-Sikorsky but never produced (1926).
  • S-34.png S-34. Six-passenger twin-boom flying-boat with two Wright J-4 Whirlwind engines, designed for Airco. Sank on first flight (1926) [X883].
  • "AIRCO" AMPHIBIAN. Development of S-34 with two 120 hp Super-Rhône engines flush with wing; marketed by Airco-Sikorsky but never produced (1926).
  • S-35.png S-35. Multimotor mail/passenger biplane with three 400 hp Gnome Jupiter engines. Not produced as such (1926).
  • S-35 Special. Same design modified with more powerful 420 hp Jupiter engines and fuel tanks, for René Fonck's 1926 NY-Paris Transatlantic attempt [no registration]. Crashed (1926).
  • Biplane to monoplane modifications. Continuing with experiments on the G-S-1 wing, several more biplanes were modified, but this time as pure parasol-wing types: JN-4D "Jennies" could be modified as UN-4 types under Restricted TC Group 2-23 (at least 6 were made), but other similar modifications were tested in 1927 on several Standard J-1s, on a wrecked Travel Air Model B (2000) [C100, c/n 150], and temporarily in 1928 on a Stearman C-3K [7775, c/n 137]. Another J-1 was modified as the SN-1 (also in 1927) with a different wing profile designated UNW-9.
  • S-36.png S-36. Development of S-34 with two Wright R-790 (J-5) engines, open cockpits, the very first US twin-engine amphibian (1927). One to US Navy as XPS-1 patrol aircraft [BuAer A-8005, c/n 1].
  • S-36A/B. Enclosed cockpit commercial examples with same engine type (1927). Five or six produced.
  • S-37.png S-37-1 "Ville de Paris". Similar to S-35 but longer range and 500 hp Gnome-Rhône Jupiter engines. Built for René Fonck as replacement, but flight canceled after Lindbergh won Orteig Prize (1927) [X1283, c/n 2]. Became the 18-passenger "Southern Star" [R1283] as first commercial transport between South American capitals and across the Andes, mostly on floats (1927).
  • S-37B.png S-37-2 (S-37B) GUARDIAN. Second aircraft built as a bomber with Consolidated (their Model 11) for an Army bomber competition [(N)X3698, c/n 1]. Evaluated at Wright Field as XP-496 but unsuitable, and subsequently sold as 20-passenger aircraft to NYRBA, Pan American's competitor on South American air lines [NR942M].
  • S-38.png S-38A AMPHIBION. Development of S-36 with more streamlined fuselage and 425 hp Pratt & Whitney R-1340 Wasp engines (1928). Used by Pan Am, Western Air Express, Curtiss Flying Service under ATC-60; evaluated by Army Air Corps as XC-6, and by Navy as XPS-2, Sikorsky's first military order.
  • S-38AH AMPHIBION. Special six-seat experimental version with 525 hp P&W Hornet A engines, for the Liberty magazine company. (1929)
  • S-38B AMPHIBION. Refined development of XPS-2 with two Wasp C (R-1340C) engines. First examples produced for Navy as PS-3 (later RS-3) (1928), followed by the commercial version used by Pan Am, Colonial, Northwest under ATC-126 (1929) and the Army Air Corps as C-6A (1930).
  • S-38B Sp. AMPHIBION. Several aircraft sold under restricted TCs (Group 2-68, -69, -74) with different cabin arrangements and seat numbers (1929). One for Ancol had Wasp SC engine.
  • S-38BH AMPHIBION. Ten-seat version with 575 hp P&W Hornet B engines, first under Group 2-190 restricted TC, then approved under ATC-356 (1930).
  • S-38BL AMPHIBION. Unidentified variant, but photo shows alternate engine installation (1930).
  • S-38BS AMPHIBION. Special 7-seat version with Wasp SC1 engines for 1933 African wildlife survey by Osa and Martin Johnson (1932).
  • S-38BT AMPHIBION. Restricted TC for 8-/10-seat versions with supercharged Wasp T1D1 engines (1933).
  • S-38V AMPHIBION. Unidentified variant sold to Pan American (1930).
  • S-38C AMPHIBION. Eight-/twelve-place version of S-38B with two 420 hp P&W Wasp C engines and less fuel; used by Inter-Island, Canadian, S.C. Johnson & Son and others, under ATC-158 (1930).
  • S-39. Smaller size high-wing amphibian prototype with two 100 hp Cirrus Hermes Mk. I inline engines atop wings (1929). Crashed.
  • S-39.png S-39A SPORT AMPHIBION. Revised 4/5-seat version with single P&W Wasp Jr. (R-985) engine atop cockpit, sold under ATC-340 (1930).
  • S-39B SPORT AMPHIBION. Improved five-seat version with increased gross loaded weight, same engine, under ATC-375 (1932). Some to Civil Air Patrol.
  • S-39C SPORT AMPHIBION. Several variants under Restricted TCs with different Wasp Jr. versions: S1A, TB or T3A (Group 2-391) (1931) and S2A (Group 2-436), the latter for Martin & Osa Johnson's African Wildlife raid (1932). One was also purchased by the Army Air Corps for evaluation as Y1C-28 (1931).
  • STANDARD X. Contrary to what can be read in different places, this sole parasol-wing prototype [X802W, c/n 1], which used the G-S-1 wing, was not a Standard J-1. Also, it didn't use a Stearman fuselage, as has also been suggested, but an unidentified one looking closer to that of a Spartan. It was used by Kane Laboratories, possibly on aerial photography work.
  • 1930 helicopter.png Direct-lift aircraft. Helicopter design drawn in 1930, submitted for patent in 1931 and approved in 1935 (Patent U.S. 1994488).
  • S-40.png S-40 CLIPPER. New 44-seat transport flying-boat for Pan American with four P&W Hornet B engines, under ATC-454 (1931).
  • S-40A CLIPPER. Two examples updated with 660 hp Hornet T2D1 engines and with landing gear removed, under ATC-562 (1935). Apparently temporarily impressed by US Navy in 1942 under the non-standard "RS-4" designation, and later returned.
  • S-41.png S-41 AMPHIBION. Fifteen-seat high-wing amphibian, a beefed-up, monoplane development of the S-38 (all previous types were sesquiplane) with two 575 hp P&W Hornet B engines (1930). Three went to the US Navy as RS-1 transports.
  • S-41A AMPHIBION. Commercial version, also with Hornet B engines, under ATC-418 (1931). One to Pan Am, operated in South America.
  • S-41B AMPHIBION. Restricted TC (Group 2-286) for 13-seat variant operated by Boston-Maine/Central Vermont under PanAm control (1930).
  • P2S.png US Navy XP2S-1 flying-boat with push-pull engines in interwing nacelle; a Navy, not Sikorsky, design (1932) [BuAer A-8642].
  • SS-2.png US Navy XSS-1 experimental scout-observation amphibian with 400 hp Pratt & Whitney R-985A Wasp Jr. engine for carrier duty [BuAer A-8972]; a US Navy, not Sikorsky design. Not built as such.
  • US Navy XSS-2. Same project modified during development with more powerful 550 hp Pratt & Whitney R-1340-12 engine instead [BuAer A-8972].
  • S-42.png S-42 CLIPPER. 32-passenger high-wing flying boat for Pan American with four Hornet S5D1G radials, under ATC-544 (1934). Two impressed by U.S. Navy from Pan Am, apparently as non-standard "RS-5" (1942); one crashed, one scrapped.
  • S-42A CLIPPER. Version with 750 hp Hornet S1EG version and longer wings, under ATC-592 (1936).
  • S-42B CLIPPER. Refined version of S-42A with Hamilton Standard propellers, same ATC (1937).
  • S-43.png S-43(A) AMPHIBION ("BABY CLIPPER"). 16/25-seat amphibian transport for Pan Am and others, with two P&W Hornet engines, under ATC-593 (1935). Army Air Corps service batch as Y1OA-8 (1937).
  • S-43B AMPHIBION ("BABY CLIPPER"). Redesigned nose, twin tails (most later reverted to single tail fin) (1935). One civilian example impressed as OA-11 (1941) but crashed.
  • VS-43B AMPHIBION. Dedicated Navy JRS-1 transport/utility production version with two P&W R-1690-52 engines (1938).
  • S-43H SKY YACHT. Special example for Howard Hughes (1935), also under ATC-593, planned for proposed 1938 world flight. Crashed in 1943 but was repaired.
  • S-43W AMPHIBION. 19-/25-seat version similar to twin-tail S-43B but with two Wright Cyclone engines, under ATC-623 (1937).
  • S-43WB. Pure flying-boat conversion of S-43W under same ATC, but apparently none were converted as such (1937).

(to be continued)
 
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  • BLR-3.png USAAC XBLR-3. Long-range bomber proposal under Army Restricted Project No. M5-35 (1938). Competed against Boeing's XBLR-1 (later XB-15) and Douglas's XBLR-2 (later XB-19) but was canceled.
  • L airliner.png ow-wing monoplane airliner project with four unknown engines, derived from BLR-3 design (1940).
  • S-44.png S-44. Large USNavy XPBS-1 high-wing patrol flying boat prototype with P&W Twin Wasp engines (1942). Sank in San Francisco Bay that same year. Dubbed "The Flying Dreadnaught" by the press.
  • S-44A.png VS-44A. Cancelled order for JR2S-1 to be used by Naval Air Transport Service (1942).
  • VS-44A FLYING ACES. 38-passenger (16- in VIP class) commercial transport derivative under ATC-752 (1942), flown by American Export Airlines, under contract with US Navy (designation JR2S-2 used only on paper).
  • S-45. Series of huge 100-passenger "Future Trans-Oceanic" clipper flying boat projects for Pan American. Initially meant to use six 1000 hp Wright Duplex-Cyclone engines (1936), it was also studied in similar landplane configuration (1938), then completely redesigned as a more streamlined 4-engine type (1940), but was cancelled with the war.
  • S-46.png S-46 (VS-300). First successful US helicopter with 75 hp Lycoming GO-145-B2 engine, using patented 1931 single-rotor design (1939). The prototype underwent 18 major modifications, including twin tail rotors, stabilizers, longer airframe, etc. with a 90 hp Franklin 4AC-176 engine (1940).
  • S-46 (VS-300A). Major redesign which set helicopter endurance record and perfected two-rotor, cyclical-pitch control system.
  • VS-301A.png VS-301A/C. Large maritime patrol flying boat projects derived from the S-44. Not built.
  • VS-302A/B. Twin-engined high-performance bomber projects. Not built.
  • VS-308B.png VS-308.png VS-308. Maritime patrol and liaison amphibian project. Not built.
  • VS-308B. Lightly armed maritime scout and liaison amphibian, a totally different design. Not built.
  • VS-311. Helicopter project for US Army Air Corps, derived from VS-300. Not built.
  • VS-312. Six-engined heavyweight commercial flying boat project. Not built.
  • S-47.png S-47 (VS-316-1). Development of VS-300A design with 165 hp Warner R-500-3 Super Scarab engine, crew of two, dual controls, evaluated by USAAF as XR-4-SI (1942).
  • S-47 (VS-316A). Refined version with 180 hp Warner R-550-1 engine (1942). Service batches for Royal Air Force as Hoverfly I (1943), and for USAAF as YR-4A-SI (1942)/YR-4B-SI (1943), some of which were transfered to Navy as HNS-1.
  • S-47 (VS-316-A-2). Main production version with more powerful 200 hp Warner R-550-3 engine, procured by USAAF as R-4B (1943), some of which went to Navy as HNS-1 (1944) but also to Royal Navy (1944) and Royal Air Force (1945) as Hoverfly I.
  • S-48.png S-48 (VS-327). Transport development of R-4 with longer fuselage with P&W R-985-AN-5 (Wasp Jr.) engine (1943). Procured by USAAF as YR-5A and R-5A (1945) (both later redesignated as H-5A), with two examples transfered to Navy as HO2S-1 (1945), and later to Coast Guard. Versions YR-5B and YR-5C were cancelled. YR-5D/R-5D (later H-5D), modified from R-5A, had nose-wheel landing gear, rescue hoist, provision for extra passenger and external fuel tank (1944), while YR-5E (later H-5E), modified from YR-5A, had dual controls (1946). A projected civilian version of R-5E was never built (replaced by S-51).
  • VS-332. Six-engined heavyweight flying-boat project, likely for U.S. Navy. Not built.
  • VS-333. Two-seat helicopter project for U.S. Army Air Forces. Not built.
  • S-49.png S-49 (VS-316B). Refined development of R-4 with 225 hp Lycoming O-435-7 engine, tested by USAAF as XR-6-SI (1943); re-engined in 1944 as XR-6A with 240 hp Franklin O-405-9 (a type used on all later versions) and evaluated as such by Navy as XHOS-1 (1944). Production was carried out by Nash-Kelvinator, becoming YR-6A/R-6A for Air Forces. Many of those were transfered to Navy as HOS-1 (1944), to Coast Guard as HOS-1G (1945), and to RAF as Hoverfly II (1945), most of which being later transfered to Fleet Air Arm and British Army. The unbuilt XR-7-SI was to test the 240 hp Franklin engine, but was replaced by the XR-6A instead.
  • Doman LZ-1A. One R-6A modified by Doman as testbed with Doman-designed hingeless rotor blades, self-lubricating rotor hub. Sikorsky not involved in the project.
  • S-50.png S-50. Design study for a small two-seat helicopter with unspecified 150 hp engine; full-scale wooden mock-up only (1943).
  • ROTO-SCOUT. No details, mentioned in a USAF report (DS-157 Balance Diagram, SER-1503 Model Spec).
  • S-51.png S-51. Refined commercial four-seater development of S-48 with P&W Wasp Jr. (R-985-AN-5) engine (a type used on all versions). Several examples purchased for evaluation by US Navy and Air Force, the latter as R-5F (later H-5F) in 1948. The dedicated USAF version was the H-5G, similar to H-5F but with rescue equipment, while the Navy and Marines used the same as HO3S-1 (nine of which were transfered to Coast Guard as HO3S-1G). The H-5H was similar to the H-5G but was an amphibian with a combination wheel/pontoon landing gear and updated equipment. The XHO3S-2 was an unbuilt modification, while the XHO3S-3 was an HO3S-1 modified with a redesigned rotor (1950). Six more commercial examples were imported by Westland in the UK to serve as models for British production, one being tried by the Royal Navy.
  • Westland WS-51 DRAGONFLY. License-built version of S-51 by Westland, with rotor blades of composite construction, and powered by a 540 hp Alvis Leonides 50 engine. Used by the Royal Navy as the Dragonfly HR.1 (1948) and Dragonfly HR.3 (some of which were later modified as Dragonfly HR.5), and by the Royal Air Force as the Dragonfly HC.2 (1950) and Dragonfly HC.4 (1952).
  • Westland WS-51 DRAGONFLY. Commercial version with 520 hp Alvis Leonides 521/1 (Dragonfly Series 1A) or 450 hp Pratt & Whitney R-985-B4 Wasp Jr. (Dragonfly Series 1B).
  • Westland WS-51A WIDGEON II. Also known as WS-51 Series 2. Version with new automobile-style fuselage (1955). Most were modifications of existing Dragonfly 1A types, but a few were newly-built examples. 24 planned Navy conversions as Dragonfly HC.7 didn't materialize (there is no indication as to what the "Dragonfly Mk.6" might have been).
 
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I would love to present you with a definitive list of Igor Sikorsky's Russian aircraft... Unfortunately, it seems like no two sources seem to agree on the allocation of certain designations...
  • According to some, the "Krugliy" monoplane was the S-9, with its "Polukrugliy" derivative being the S-11. However, other sources give the "Krugliy" as the S-11, and the "Polukrugliy" as the S-11A.
  • According to some, the "Grand" airliner was the S-9, while others give it as the S-21.
While most sources agree that S-22 to S-27 were allocated to the Ilya Muromets series, allocations differ widely:
  • The IM series was divided into 7 main versions, designated IM-A, IM-B, IM-V, IM-G, IM-D, IM-E and IM-J (following the order of the Cyrillic alphabet); however, the Sikorsky Archives website (contrary to the other sources) doesn't mention an IM-A version as such, and divides the others into sub-versions as IM-B/IM-B', IM-V/IM-V', IM-G/IM-G', IM-D/IM-D'. That wouldn't be such a problem in itself, but while most sources agree that IM-A was S-22, and that all IM-B and IM-V aircraft were S-23, the Archives give the B/B' series as S-22 and S-22A, and the V/V' series S-23 and S-23A. Other sources still have grouped IM-A and IM-B under S-22, with S-23 being only for IM-V...
  • While most sources seem to agree that the G series was divided into S-24 (G-1) and S-25 (G-2/G-3), the breakdown and production numbers for each differ dramatically. Also, the Archives call the S-24 as just G and the S-25 as G'.
  • Many sources give the D and E series as being S-26 and S-27, respectively. The Archives doesn't mention an E version; instead they give the D as S-26, and the D' as both S-26 and S-27... Other sources still consider D and E to be S-25 and S-26, with S-27 being the unbuilt J series...
So although we do have a more or less precise account of all the different aircraft and versions produced or projected while in Russia, it seems virtually impossible to establish a coherent correspondence. I suppose some will argue that the Sikorsky Archives certainly should know better, but it's not the case. Not only they have been clearly wrong on several occasions, but it is likely that whatever info Igor Sikorsky had managed to take away with him out of Russia (or remembered) could not compare to the archives that researchers in Russia and Ukraine have had access to.
 
Stargazer said:
Westland WS-51 DRAGONFLY.
Click to expand...
Not so long back there was a lengthy argument in an Air Britain forum about whether the WS-51 ever was officially the WS-51. I believe it was confirmed that the manufacturer's data plates were actually stamped S-51.
I'll have to dig out the thread.
 

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