Post by aerofoto - HJG Admin on May 29, 2016 10:11:17 GMT
PICK OF THE PROPS
"IMAGINE" .... it's 1958/59 come early 1960.
Buddy Holly, Ritchie Valens, and Big Bopper are "gone" .... but .... the music hasn't died completely because Elvis's now topping the charts along with Bill HAILEY & THE COMETS.
EISENHOWER's in the White House .... as the 34th US president.
The Korean war's over .... but the Cold War continues .... and Vietnam's not (officially) begun.
Despite failure of the British COMET 1 earlier during the decade jetliners are now acknowledged as being the future of world civil aviation.
BOEING, DOUGLAS, and CONVAIR/GENERAL DYNAMICS are each vying against one'another for a slice of the lucrative world market for first generation US-built 4-engine narrow-body civil jetliners .... whilst LOCKHEED has built "a turboprop" in the form of the L-188 ELECTRA .
Airports (and aerospace manufacturers) ready or not .... the civil Jet-Age has dawned and air transport, and the world, are about to be forever transformed.
Any number of the great pounding piston powered prop liners remain in service though .... progressively relegated to less prestigious routes or being disposed of by major operators (now re-equipping with jets), to be scrapped, or to embark upon new leases of life among smaller/less significant airlines. A few of the lucky ones will soldier on into the next millennium .... their big props flogging the air longer than most .... albeit that their glory days "are now over".
There's a new sound in the sky now as turbojet powered civil jetliners begin filling the skies with noise .... and smoke .... whilst also impressing the traveling public with their incredible performances (in comparison with that of smaller and slower prop liners among the previous generation of civil aircraft) and the new standards of comfort and service they afford.
The 1950's/60's era represented possibly "the greatest" period of change/advance ever witnessed within world civil aviation .... with aircraft/airlines transitioning from piston/radial engines driving big propellers, to turboprop, then turbojet engine power and fast narrow-body civil jetliners .... followed by the equally rapid transition to fanjet/turbofan power during the early 1960's, then big high-bipass ratio turbofan engines and the even larger 2nd generation series of wide-body civil jetliners by the early 1970's .... with the advent of A300B, B747, DC-10, and L-1011. All of which occurred within the relatively short space of less than a couple of decades.
In the USA .... civil aviation and development of progressively larger, more logistically capable, all-metal piston/radial powered aircraft had evolved rapidly throughout the 1930's and 1940's. By this period DOUGLAS had developed "the most respected" reputation among major aerospace manufactures around the world .... through development of its DC-1, DC-2, DC-3 family of prop liners, and was, by the early 1940's, about to launch its DC-4. During this same period LOCKHEED had also launched its smaller but successful L-10 ELECTRA and L-18 LOADSTAR series of proliners and was developing its pressurized EXCALIBUR .... whilst BOEING had responded to these challenges with its own B247 and pressurized B307 STRATOLINER aircraft.
Suddenly .... the future of US aviation development was interrupted and seemed to be thrown into disarray with Americas involvement with WW2 .... from December 1941. The development of civil aviation was suspended and almost entirely refocused upon design, and production, of military/combat type aircraft .... with almost all existing civil aircraft being impressed into war service whilst developing civil aviation projects were just as hastily re-engineered for military use. To this extent the DOUGLAS DC-3 and DC-4 became C-47 and C-54 transports respectively .... the BOEING B247 and B307 became the C-73 navigational trainer and C-75 transport respectively also .... whilst the LOCKHEED EXCALIBUR (which had by this time become the CONSTELLATION and had yet to fly) was re-designated as the C-69 transport .... each of which were impressed for military service roles.
Although civil aviation development would not be resumed (in earnest) until after 1945, Americas impressive mobilization effort during WW2 actually pathed the way for its future success and world conquest .... through experience gained from the organized and efficient mass production of aircraft, development of improved aviation infrastructure across the USA in order for larger aircraft types and increased traffic flow to be accommodated, and establishment of what later became the foundation for future civil air routes both across the USA and to abroad.
Considerations in regard to the future of US civil aviation were not entirely abandoned during wartime though .... especially when Howard HUGHES (accompanied by Jack FRYE), whom had been a driving force behind LOCKHEED development of the CONSTELLATION, flew an L-049/C-69 (# 43-10310), in TWA TRANSCONTINENTAL LINE livery, non-stop from Burbank/California to Washington DC, in just 6 hours 27 minutes (and 25 seconds) on April 17th 1944 .... in what was a spectacular achievement and publicity stunt, for the time (given the performance capabilities of comparable pre-wartime propliners and the continuing US war effort), and which also fore-shadowed the future of commercial air services within the USA.
After WW2 .... converted B17, B24, and even HALIFAX and LANCASTER bombers, served as interim commercial transports in various parts of the world. Whilst logistically capable these aircraft were entirely unsuitable for use as civil airliners though.
Originating during 1939 .... LOCKHEED development of its pressurized CONSTELLATION (like that of the DC-4) had been interrupted by WW2.
Consequently the prototype aircraft version (NX25600 .... with its up-scaled P-38 LIGHTING wing design and powered by 4X 2,200 HP R-3350 radial engines) did not fly until January 9th 1943 .... designated XC-69.
The USAAF had by this time placed orders for some 202X C-69 transports .... however .... only 22X of these airframes were produced, of which only 15X were ever delivered prior to the cessation of hostilities during 1945, and at which point the balance of this military order, for some 180X remaining airframes, were promptly cancelled. Those airframes already under construction, or planned for production, were then hastily converted for civil use .... re-designated L-049 CONSTELLATION aircraft.
Re-configured for up 60 PAX and powered by 4X 2,200 HP R-3350 radial engines, the civil L-049 first flew on July 12th 1945. TWA took delivery of the first aircraft on November 14th 1945 (followed by PAN AMERICAN WORLD AIRWAYS on January 6th 1946) .... and launched the first ever commercial CONSTELLATION service (operated by N86511/fleet # 555 "Star Of Paris") over its New York/La Guardia to Paris/Orly route (via Gandar/New Foundland and Shannon/Ireland .... over some 17 hours flying time) from February 5th 1946 .... followed by PAN AMERICAN WORLD AIRWAYS whom operated its first CONSTELLATION services over the airlines New York/La Guardia to Bermuda route from February 1946 also.
At this early stage of development LOCKHEED .... and its CONSTELLATION .... had an approximately 18 month lead over their DOUGLAS and BOEING competition.
The L-049's service entry was marred by a number of incidents/technical difficulties (cabin supercharger shaft fractures occurred causing hydraulic fluid to spray over engines from broken lines risking engine fires .... AND ..... arcing of through-studs that carried electrical current between the wings and pressurized fuselage .... each resulted in very early introductory problems), and at least one major accident, involving a TWA test flight on July 11th 1946, and which resulted in a 6 week grounding of the type from July 1946. Some 95 modifications were then applied to these aircraft prior to their being successfully returned to service. Some 88X L-049/C-69 airframes were produced by LOCKHEED between 1942 and 1946. A small number of civil L-049's were later modified with increased fuel capacity .... and re-designated L-149's.
The first exclusively civil production CONSTELLATION .... designated L-649 (registered NX101A) .... powered by 4X 2,500 HP R-3350 radial engines and based on the same fuselage as that of the preceding L-049 .... was intended for US domestic routes and first flew October 19th 1946. This heavier aircraft version entered service with EASTERN AIR LINES from May 1947. The L-649 also featured an optional detachable Speedpack utility/bin (below its central fuselage) to increase cargo capacity over short routes only .... for 3%/10 KT performance penalty. Some 16X L-649 airframes were produced by LOCKHEED between 1946 and 1951 .... of which 6X aircraft were produced as higher gross weight L-649A's (strengthened for additional fuel capacity and range) .... as delivered to CHICAGO & SOUTHERN AIR LINES from October 1950. A number of original L-649 airframes were also later upgraded to superior L-749 and L-749A specifications.
Production of the higher weight, long range, over-water CONSTALLATION series followed .... designated L-749 and L-749A .... also based on the L-049/-649 fuselage length (a few of these airframes were fitted with WX radar which resulted in a slightly lengthened nose) .... powered by 4X 2,500 HP R-3350 radial engines (fitted with Jet Stacks that enabling superior airspeed performance .... albeit with increased noise and which also exhibited significant flame effects too .... especially conspicuous during evening flights .... and to such an extent that it did occasionally disconcert unaccustomed PAX ). The L-749 first flew on March 14th 1947 .... with AIR FRANCE taking delivery of the first aircraft on April 18th 1947 .... followed by PAN AMERICAN WORLD AIRWAYS during June 1947, and with whom the type inaugurated the airlines around-the-world service (operated by NC86530 "Clipper America") also from June 1947. Development of the L-749 also coincided with a sizable military supply contract which later sustained the CONSTELLATION production line during a period of declining civil orders. What evolved from this renewed military interest was the heavier L-749A .... powered by 4X 2,700 HP "military standard" R-3350 radial engines with Curtis type electric propellers, minor engine nacelle modifications, and also featuring a strengthened fuselage and landing gear.
Further developed for commercial use .... SOUTH AFRICAN AIRWAYS took delivery of the first civil production L-749A during August 1950 .... followed by TWA. LOCKHEED also provided conversion kits to enable upgrades of former L-649 aircraft to superior L-749 specifications. Both L-749 and L-749A became the most numerous of CONSTELLATION type aircraft .... with some 113X civil airframes being produced by LOCKHEED between 1947 and 1951. A freighter version of the L-749A .... along with a turboprop powered L-749B .... were also proposed by LOCKHEED, but, cancelled due to insufficient interest and the unavailability of suitable power plants respectively.
During the post war Soviet imposed Berlin blockade ..... from June 24th 1948 until May 12th 1949 .... USAF C-69 transports flew some 6 million PAX miles, operating supply/relief flights between Westover AFB, Massachusetts, USA , to the UK, and on to Rhein-Main AFB, Frankfurt, in the then West Germany .... as part of the allied Berlin Airlift effort.
Production of the early/original CONSTELLATION series ceased from 1951 as, spurred-on by both TWA and competition from DOUGLAS .... LOCKHEED successfully evolved the aircraft's design into the larger, and even more logistically capable, L-1049 SUPER CONSTELLATION series that was to become regarded, by many, as the ultimate in prop liner development .... during this particular period.
To counter the DC-6 and DC-7 several versions of L-1049 SUPER CONSTELLATION aircraft were developed by LOCKHEED .... originally conceived during the early 1940's, but, suspended due to wartime priorities and the unavailability of suitable power plants at the time. The L-1049 incorporated more than 500 improvements/modifications over preceding L-049/649/749 aircraft versions .... among which included an 18 FT 4 IN fuselage stretch with re-designed rectangular cabin windows (as opposed to the circular cabin port holes of earlier production CONSTELLATION series aircraft) and larger cockpit windshields, strengthened landing gear, larger tri-tail surfaces, increased fuel capacity options .... for greater range, superior de-icing equipment, improved cabin heating efficiency and pressurization system comforts, along with more powerful engines too .... enabling progressively higher payload capabilities, performance, and endurance.
The first L-1049 was converted from the original CONSTELLATION prototype (re-registered NX6700). This aircraft first flew on October 13th 1950 .... powered by 4X P&W R-2800 radial engines. Some 24X initial production version L-1049 airframes were produced by LOCKHEED .... powered by 4X 2,700 HP R-3350 radial engines .... the "then" best powerplant available for "civil use", but, which also resulted in these aircraft being somewhat under-powered when operating at/near MGW.
Both civil L-1049A and -B aircraft were also produced by LOCKHEED .... along with military versions for both USAF-MATS and USN service roles. Some 330X CONSTELLATION type aircraft would eventually operate under numerous C-121, EC-121, JC-121, NC-121, TC-121, VC-121, YEC-121, PO-1W, R7V, and WV series designations. Early aircraft deliveries to the US military services were powered by 4X PRT equipped 3,250 HP "military standard" turbo-compound radial engines .... whilst later aircraft deliveries (most of the military inventory) were powered by 4X PRT equipped 3,400 HP "military standard" R-3350 turbo-compound radial engines.
A number of these aircraft were re-designated later during their military service after having been subject to various conversions for specific reconnaissance/surveillance and scientific research type roles. Military operated CONSTELLATION aircraft saw service during both the Korean and Vietnam conflicts .... some of which remained operational well into the 1970's.
Refitted with 4X 3,250 HP PRT equipped R-3350 turbo-compound radial engines (upon this power plant becoming available for "civil use") .... the L-1049C first flew on February 17th 1953 (registered PH-TFP). This aircraft entered service with KLM ROYAL DUTCH AIRLINES from August 1953, followed by AIR FRANCE, EASTERN AIR LINES, and TRANS CANADA AIRLINES .... and of which some 56X airframes were produced by LOCKHEED. TWA (by now a major CONSTELLATION operator) ordered, but, never took delivery of this particular version of the SUPER CONSTELLATION. The L-1049C featured improved cabin sound insulation and became the first of the "civil CONSTELLATION series" to be fitted with turbo-compound power plants .... which enabled both a superior ROC and higher cruising airspeed. Although still lacking DC-6B range, the L-1049C was otherwise comparable in performance, whilst also being capable of transporting greater payloads.
The L-1049D freighter followed .... and first flew during September 1954. This aircraft was essentially an L-1049C .... fitted with a strengthened floor and 2 forward and aft located port side main deck cargo doors. Only 4X of these airframes were ever produced by LOCKHEED .... specifically for SEABOARD & WESTERN AIRLINES .... and entered service with the airline during late 1954 (3X of which were leased to BOAC between 1955 and 1956 after the COMET 1 groundings) .... 2X of which were also later converted to superior L-1049H specification. At the time of its service entry the L-1049D was the worlds largest civil cargo aircraft.
The L-1049E CONSTELLATION represented a higher gross weight PAX configured version of the preceding L-1049D freighter .... of which some 18X airframes were produced by LOCKHEED. A number of original L-1049E orders were converted to the following and superior L-1049G specification prior to production.
Whilst the CONSTELLATION improved with each successive aircraft version, none of the established series were capable of flying non-stop transatlantic services .... from east to west .... against the prevailing meteorology. Even the earliest B707, COMET 4, and DC-8 jetliners were often similarly range impaired when operating to the US east coast from either European or UK ports .... imposing refueling/technical stops at either Shannon/Ireland, Keflavik/Iceland, or Gandar/New Foundland. Similar operational impositions applied to the DC-6B and DC-7B also.
Also based on the L-1049C airframe .... the L-1049F first flew flew during early 1955 and entered USAF-MATS service from August 1955 .... designated as the C-121C long range transport aircraft. This military version was equipped with wing tip fuel tanks, WX radar, and an APU .... whilst also featuring additional airframe strengthening in order to promote future conversion to turboprop power.
Between 1954 and 1955 4X aircraft, based on the R7V-1 airframe, were produced by LOCKHEED as prototypes for USAF and USN military air transport service roles .... originally designated L-1249A CONSTELLATION aircraft .... powered by 4X 5,500 BHP P&W YT34-P-12A turboprop engines with Hamilton Standard Hydromatic propellers, and capacity for 106 PAX or 73 stretcher cases. Featuring the same wing, fuselage, and landing gear strengthening applied to the military C-121C, the wingspan of these particular aircraft was shortened by 6FT 7IN, but, equipped with additional fuel capacity in the form of optional wing tip tanks. Re-designated R7V-2 .... this aircraft first flew on September 1st 1954 and was delivered to the USN on September 10th 1954 .... followed by USAF version .... re-designated YC-121F .... which first flew on April 5th 1955 and was delivered during July 1955. During flight testing these turboprop powered R7V-2 and YC-121F aircraft attained airspeed of some 415 MPH (479 MPH was actually achieved during a controlled 20* dive) .... to become "the worlds fastest transport aircraft" at the time. Civil versions of this turboprop development were also proposed by LOCKHEED .... re-designated L-1249B CONSTELLATION aircraft (based on the L-1049E fuselage) .... promising range in excess of 4,100 miles and London/Moscow, Los Angeles/Hawaii, and London/New York (via Gandar/Newfoundland) type services in 7 hours, 6 hours, and 9 hours respectively, but, little interest was expressed by civil operators whom, at the time, remained content with the performance their piston powered CONSTELLATION aircraft fleets. Beyond their relatively short USAF and USN military air transport service roles, the fuselage and tail sections of the only 4X R7V-2 and YC-121F aircraft ever produced by LOCKHEED, were used to construct composite civil L-1049G and L-1049H airframes. A single R7V-2 airframe was also later used to flight test the ALLISON 501-D turboprop engine, during LOCKHEED development of the L-188 ELECTRA, and prior to it being scrapped.
As competition between the CONSTELLATION and both DC-6B and DC-7 intensified .... LOCKHEED responded with L-1049G ("Super G") powered by 4X PRT equipped 3,400 HP R-3350 turbo-compound radial engines. Accommodating up to 95 PAX .... this aircraft could also be fitted with optional 1,037 gallon wingtip fuel tanks to extend range by more than 1,000 miles .... along with an optional WX radar unit that (when fitted) resulted in a 3 FT 2 IN nose extension .... and either Hamilton Standard or Curtis electric type propeller options .... among more than 100 other refinements over preceding SUPER CONSTELLATION aircraft versions. The L-1049G first flew on December 12th 1954 and entered service with NORTHWEST AIRLINES, and TWA, from 1955. Some 104X L-1049G airframes were produced by LOCKHEED .... among which included L-1049G/01 aircraft featuring a strengthened wing and permitting a slightly higher MTOW .... as delivered to REAL BRASIL and VARIG BRAZILLIAN AIRLINES from July 1955.
A convertible PAX/freight configured re-development of the L-1049G followed .... designated L10409H ("SUPER H") .... and which first flew on November 20th 1956. Based on the strengthened C-121C airframe .... this aircraft featured L-1049G improvements which promoted further increased payload capabilities with capacity for up to 120 PAX. Entering service with QANTAS AIRWAYS from December 1956 .... some 53X L-1049H airframes were produced by LOCKHEED. A number of earlier production SUPER CONSTELLATION aircraft were later upgraded to L-1049H specification. L-1049H aircraft were powered by 4X PRT equipped 3,400 HP R-3350 turbo-compound radial engines although some later production airframes ..... re-designated L-1049H/01 aircraft .... were powered by the EA series of these engines (also fitted to the later L-1649 STARLINER) with a higher METO rating and certified for a slightly higher MTOW .... as delivered to the FLYING TIGER LINE during 1957. 2X L-1049H/02 along with 2X L-1049H/07 designated aircraft were also produced by LOCKHEED .... featuring additional landing gear improvements.
Turboprop powered L-1049J versions of the SUPER CONSTELLATION (based on the established L-1049H fuselage, R7V-2 wing, and fitted with further increased fuel capacity) were also proposed by LOCKHEED, but, never produced for civil use.
By the mid 1950's, DOUGLAS and its long range DC-7C (by this time a year in advance of LOCKHEED development), were beginning to pose a major threat to the CONSTELLATION. LOCKHEED therefore sought to further enhance its established SUPER CONSTELLATION design. This resulted in the L-1649A STARLINER .... based on the same fuselage length (featuring a standard WX radar) as that of the L-1049 SUPER G .... for up to 99 PAX, a completely new/re-designed straight-tapered wing of increased span .... promoting greater fuel capacity .... and powered by 4X PRT equipped 3,400 HP R-3350 turbo-compound radial engines. This combination of modifications was intended to promote trans-Atlantic and trans-polar type range along with superior airspeed performance .... in order to counter the DC-7C. The prototype L-1649A STARLINER (registered N1649) first flew on October 11th 1956. This aircraft (the last of the CONSTELLATION series) commenced TWA "JESTREAM" services on the airlines trans-Atlantic routes between New York, London, Paris, and Frankfurt, from June 1st 1957 .... followed by trans-polar services between the US west coast and Europe. AIR FRANCE then introduced "SUPER STARLINER" Paris/Tokyo (via Anchorage), and Paris/Mexico City (via Montreal and Chicago) services from August 1957 .... followed by LUFTHANSA GERMAN AIRLINES operated "SUPER STAR" services between Dusseldorf, Frankfurt, Paris, and New York, from 1959 .... these being the only 3 airlines to ever order L-1649A aircraft from the LOCKHEED production line. Although the STARLINER version of the SUPER CONSTELLATION family represented "the pinnacle of propliner design" and offered superior range .... whilst also being slightly faster too .... its airspeed performance was little superior to that of the DC-7C. The higher cost of the L-1649A, and imminent introduction of trans-Atlantic jetliner services (from 1958), conspired to result in only 44X airframes ever being produced by LOCKHEED between 1956 and 1958 (the only stage of the CONSTELLATION production which lost money for LOCKHEED) .... all of which had been replaced by jetliners on trans-Atlantic services by 1961.
A small number of CONSTELLATION and STARLINER aircraft (including some original military airframes too) were later converted to freighters .... some of which continued to operate cargo services on behalf of less significant operators well into the 1970's .... and among which also included a small number of turboprop conversion od militat designated CONSTELLATION aircraft types. The last scheduled commercial CONSTELLATION services were operated by QUISQUEYANA DE AVIACION .... of the Dominican Republic .... during 1979 .... using what were, then, among the last remaining airworthy L-049's and L-749's in existence, on the airlines daily flights between Santo Domingo and San Juan.
The tri-tail serpantine silhouette of the CONSTELLATION and STARLINER have since been regarded, by many, as an aviation legend and possibly one of, if not "the most", elegant of aircraft designs ever produced.
The success of the C-54/R5D SKYMASTER (DC-4) as a military transport aircraft during WW2, and its post war popularity among airlines, became the foundation upon which DOUGLAS proposed to develop a larger and improved version of this particular aircraft .... in the form of the DC-6. Originally intended as a military transport the war had ended before this new aircraft type could enter USAAF service. This .... along with BOEING and LOCKHEED development of their respective pressurized B377 STRATOCRUISER and L-049/649/749 aircraft, also aimed at the rapidly growing post war US civil aviation market, prompted DOUGLAS to redevelop its DC-6 design for civil use in order to remain competitive.
The DC-6 retained the basic DC-4 wing design .... but .... incorporated a 6 FT 9 IN fuselage stretch and featured large square cabin windows (as opposed to circular cabin port holes of the DC-4), cabin pressurization, and a modified tail surface.
LOCKHEED production of the first L-049's having been reserved for Howard HUGHES/TWA imposed later than desirable delivery schedules for other prospective CONSTELLATION operators .... forcing AMERICAN AIRLINES, and UNITED AIR LINES, to negotiate with DOUGLAS .... and which resulted in AMERICAN AIRLINES then becoming launch customer for the DC-6 with an order for 50X aircraft. The civil DC-6 first flew on June 29th 1946 powered by 4X 2,100 HP R2800 radial engines .... although the original military intended prototype version of this aircraft had already flown (designated XC-112A .... later re-designated YC-112A) on February 15th 1946. Deliveries to AMERICAN AIRLINES, and UNITED AIR LINES, commenced from November 1946 .... with the first DC-6 services being operated by AMERICAN AIRLINES from April 1947.
This initial production aircraft was marketed in 2 different variants .... the DC-6-1156 version, powered by 4X 2,400 HP R2800 CA-15 radial engines (with water injection), and intended for short/medium type US domestic services with capacity for up to 68 PAX .... and the heavier DC-6-1159 version, powered by 4X 2,400 HP R2800 CB-16 radial engines (with water injection), equipped with additional fuel tanking and intended for longer over-water/transcontinental type services with capacity for up to 64 PAX. A series of inflight fires (including a fatal UNITED AIR LINES accident on October 24th 1947) marred the DC-6's service entry and which forced a 4 month grounding of the aircraft from late 1947. The cause of these incidents was eventually traced to fuel venting into the aircraft's cabin heating intakes. Once modified .... DC-6 services were successfully resumed from early 1948 and without similar occurrences. These aircraft were quickly proven to offer performance superior to that of the early CONSTELLATION series. Some 176X airframes .... of the initial DC-6 version .... were produced by DOUGLAS between 1946 and 1951.
In attempt to further better the CONSTELLATION, and appeal to the equally rapidly growing civil air freight market too, the DC-6A LIFTMASTER was developed by DOUGLAS. This was a pure freighter redevelopment the original aircraft design .... featuring a 5FT fuselage stretch (often devoid of PAX cabin windows) over that of the preceding DC-6 and with fore and aft located port side cargo doors, a strengthened floor .... and offering improved payload capabilities. The DC-6A first flew on September 29th 1949 .... powered by 2,400 HP R2800 CB-16 radial engines .... and entered service with SLICK AIRWAYS from April 1951.
Some 77X DC-6A airframes were produced by DOUGLAS .... the design of which, at the request of airline customers, was also later evolved into a convertible PAX/freighter version .... designated DC-6C .... and which could be configured for up to 77 PAX, or 13 tons of freight, or a combination of both. Some later production DC-6A aircraft were powered by 2,500 HP R2800 CB-17 radial engines, and number of original production aircraft were later converted to DC-6C specifications.
The DC-6A also appealed to the US military and resulted in orders for some 166X airframes .... designated C-118 LIFTMASTER in USAF service and R6D-1 in USN service (both of which saw service during the Korean conflict) .... along with a number of VC-118/A designated aircraft for presidential/VIP type service roles.
The commercial need to keep pace with/out-do LOCKHEED, and its CONSTELLATION, encouraged DOUGLAS to develop what then became the "ultimate" DC-6 aircraft .... in the form of the DC-6B .... featuring a further 1FT 1 IN fuselage stretch over that of the DC-6A/C and with capacity for up to 107 PAX. The DC-6B was once again marketed in 2 different variants .... the DC-6B-1198A version, powered by 4X 2,400 HP R2800 CB-16 radial engines (with water injection), intended for short/medium type US domestic services and with capacity for up to 89 PAX .... and the heavier DC-6B-1225A version, powered by 4X 2,500 HP R2800 CB-17 radial engines (with water injection), equipped with additional fuel tanking and intended for longer over-water/transcontinental type services with capacity for up to 89 PAX. Both aircraft were additionally marketed with either Hamilton Standard or Curtis electric type propeller options .... featuring a constant-speed reversible pitch. The DC-6B first flew on February 10th 1949 .... and entered service with UNITED AIRLINES from April 11th 1951 .... followed by AMERICAN AIRLINES from April 29th 1951 .... and PAN AMERICAN WORLD AIRWAYS from April 1952. Some 288X DC-6B airframes were produced by DOUGLAS between 1949 and 1958.
Despite arrival of B707 and DC-8 jetliners on the civil aviation scene from the late 1950's, DC-6's remained popular among major airlines around the world .... and well into the late 1960's. Many formerly PAX configured airframes were later converted to pure freighters .... including 2X swing tail DC-6B freighter conversions undertaken by SABENA BELGUIM WORLD AIRLINES .... re-desiginated DC-6B-ST aircraft. A small number of DC-6 aircraft were also later converted to water bombers and for aerial spraying type operations .... such as those operated by the French SECURITE CIVILE and Canada's CONAIR respectively. Some of these aircraft continued operating well into the 1990's.
The DC-6 .... particularly in DC-6B form .... became regarded as "one of" the finest, and most economic, of prop liners ever produced .... to such an extent that it even outlived the service of its larger and more powerful DC-7C counterpart.
Successful though the DC-6 was .... continued intense competition between DOUGLAS and LOCKHEED/the CONSTELLATION (along with BOEING and its B377 STRATOCUISER by this time also), spawned the development of larger and even more capable aircraft types .... spurred-on also by the airlines whom were seeking still greater range, capacity, and performance .... as both aircraft manufacturers, and civil operators, sought competitive edges.
When LOCKHEED announced its development of the turbo-compound powered L-1049C SUPER CONSTELLATION .... DOUGLAS, encouraged by AMERICAN AIRLINES support (payment of a pre-production order of 25 airframes), responded to this LOCKHEED threat by developing (what it anticipated would be) a larger and superior performance, similarly turbo-compound powered, version of its DC-6B .... in the form of the DC-7 .... featuring a 3 FT 4 IN fuselage stretch over that of the DC-6B with capacity for up to 95 PAX and retaining the DC-6B tail surface. The DC-7 first flew on May 18th 1953 powered by 4X PRT equipped 3,250 HP R3350 turbo-compound radial engines .... and entered service with AMERICAN AIRLINES from November 1953. Despite the new turbo-compound engines providing greater power .... service entry of the DC-7, and L-1049C also, were frustrated by a high incidence of engine failures resulting in diversions and schedule disruptions .... and which was believed (in part) to have been a consequence of competition between airlines, with some operators opting to maintain higher, than desirable, cruise power settings as a means of achieving faster/shorter point-to-point air times in an attempt to achieve competitive edges over one'anther. Some 102X airframes .... of the initial DC-7 version .... were produced by DOUGLAS from 1953 all of which entered service among the US carriers.
Production of the heavier DC-7B followed .... and which first flew on April 25th 1955, powered by 4X PRT equipped 3,250 HP R3350 turbo-compound radial engines. This aircraft .... some of which were equipped with engine nacelle saddle tank modifications/extensions to promote additional fuel capacity for increased range .... entered service with PAN AMERICAN WORLD AIRWAYS on June 13th 1955. Although the DC-7/B represented significant technical advances both aircraft versions struggled to meet their intended/designed range projections (non-stop trans-Pacific/trans-Atlantic/trans-polar type services being quite impractical even under the most favorable of circumstances) .... whilst also suffering excessive cabin vibration and noise impositions/discomforts than the preceding DC-6B. None-the-less .... some 111 DC-7B airframes were produced by DOUGLAS from 1955.
When jets began replacing props during from the late 1950's some DC-7B operators converted a number iof these airframes to pure freighters .... re-designated DC-7BF aircraft.
Committed to resolving the shortcomings of its DC-7/B series .... DOUGLAS embarked upon a major revision of the original aircraft design. This saw development of the DC-7C .... featuring a 3FT 4 IN fuselage stretch over that of the preceding DC-7/B with capacity for up to 105 PAX and a modified/lengthened tail surface. The aircraft's inboard wing chord sections were also each lengthened by 5 FT .... which re-positioned the engine nacelles further from away from the fuselage whilst increasing overall wingspan by 10 FT, promoting additional fuel capacity for greater range, and which also had the desirable effect of reducing cabin vibration and engine noise levels. These modifications, and greater power, combined to result in a 25% performance gain over that of preceding DC-7/B. The DC-7C first flew on December 20th 1955 powered by 4X PRT equipped 3,400 HP R3350 turbo-compound radial engines .... and entered service with PAN AMERICAN WORLD AIRWAYS on June 1st 1956. Given the aircraft's range improvements .... the name DC-7C was popularly corrupted to "SEVEN SEAS" .... implying there was no longer a ocean/sea body on the earths surface which these aircraft could not successfully traverse non-stop. Some 128X DC-7C airframes were produced by DOUGLAS between 1955 and 1958 .... exceeding production of the LOCKHEED L-1649A STARLINER (1 year behind DC-7 in its development) by a considerable margin, and far exceeding BOEING production of its B377 STRATOCRUISER, whilst not approaching anything like the sales success of its own preceding DC-6 counterpart .... however .... B707 and DC-8 jetliners were, by 1958, already entering service and beginning to conquer the worlds air routes in spectacular fashion, being met with favour by both airlines and the traveling public alike.
The DC-7 became the last in the line of famous DOUGLAS prop liner aircraft. A RR RYNE turboprop powered version of the DC-7 .... designated DC-7D .... was proposed by DOUGLAS, but, was not developed given the companies commitment to its DC-8 and the worlds new-found favour in the form of 1st generation narrow-body- civil jetliners. DC-7's remained in service throughout the 1960's .... with dwindling numbers continuing to operate (mostly as converted freighters) until the 1980's.
BOEING .... prior to WW2 .... had not been a conspicuously successful producer of civil aircraft, but, throughout the 1930's, was determined to establish a foothold within the rapidly developing US commercial aviation market. Though neither of its pre-war B247 and B307 STRATOLINER aircraft had realized spectacular production runs (in comparison with DOUGLAS DC-1/2/3/4 and LOCKHEED L-10/18 sales successes) .... albeit that prospects for the B307 were interrupted by military priorities during WW2 .... the substantial post war growth of commercial aviation within the USA, and around the world, was to change everything .... and quickly evolve .... as would the destiny of the BOEING company too as a result of new opportunities being promoted by this evolution.
The BOEING challenge to post-war DOUGLAS and LOCKHEED dominance in civil aviation was manifested in the form of its larger and more luxurious B377 STRATOCRUISER aircraft .... based on its military C-97 STRATOFREIGHTER design .... which had been developed from its B29 and B50 SUPERFORTRESS which had entered military service from 1944 .... and had also been evolved into the KC-97 STRATOTANKER.
Like the preceding C-97/KC97 .... the B377 featured a pressurized double-bubble fuselage configuration with capacity for up to 86 PAX, and which included a lower deck lounge/bar and PAX sleeping berths .... promoting unrivaled airborne luxury that (possibly) was not surpassed until the advent of 2nd generation civil jets in the form of wide-body B747, DC-10, and L-1011 TRISTAR during the early 1970's. Development of the B377 commenced from 1945 when BOEING company president Bill ALLEN authorized/risked the production of 50X airframes .... without a single customer pre-commitment. Any risk involved with this decision was (perhaps) minimized by the fact that any unsold airframes could, if necessary, be modified/re-adapted to military C-97/KC-97 freighter/tanker aircraft specifications.
Despite the aircrafts much higher unit cost, but, confident also in both the potential of this big new aircraft (based on known C-97 performance earlier during 1945), PAN AMERICAN WORLD AIRWAYS became launch customer for the B377 upon placing an order for 20 aircraft during November 1945 .... valued at some $25,000,000 (1945) and which became the, then, largest airline order in commercial aviation history.
The B377 STRATOCRUISER first flew on July 8th 1947 powered by 4X turbo-charger equipped 3,500 HP R4860 radial engines (unlike other propliner powerplants of the period .... as well as supporting what was regarded as the "fastest wing" of its time) .... and entered service with PAN AMERICAN WORLD AIRWAYS on September 7th 1948 on the airlines San Francisco/Honolulu route (later extended to Europe .... and and to the east .... as far afield as Beirut, Singapore, and Tokyo) .... followed by AMERICAN OVERSEAS AIRWAYS, and BOAC, on trans-Atlantic services between New York/London .... then NORTHWEST AIRLINES, and UNITED AIR LINES, over US trans-continental routes and services to Hawaii by early 1950.
These large aircraft were affectionately dubbed "The Ocean Liner Of The Skies" (this being a time when more PAX undertook trans-oceanic travel by sea rather than air) and may be regarded as the "jumbo" of their era .... the B377 STRATOCRUISER could be configured for up to 114 PAX in a high density seating configuration. Though large, fast, and unrivaled in the class of luxury it afforded, operating economics were not in the favor of these aircraft .... since the STRATOCRUISER was both a high-cost acquisition and expensive to operate. Being heavy it was also particularly airfield demanding and therefore restricted to the worlds largest airports only. For all its size/spaciousness and advanced engineering .... head-space on the B377 STRATOCRUISER was actually several inches less than that on the DC-4 which could, in a high density configuration, accommodate more PAX than most STRATOCRUISER aircraft were configured for, whilst also being considerably cheaper to operate. The aircrafts early reputation was also marred by the complexity and unreliability of its 26 cylinder P&W engines and Curtis Electric propeller combination .... which resulted in at least 2 major disasters among a number of other serious accidents/incidents throughout the 1950's.
Some 56X B377 STRATOCRUISER airframes were produced by BOEING between 1947 and 1950. These aircraft were produced under several designations .... each of which differed cosmetically in regard to their cabin window configurations (some aircraft featuring round, rectangular, or a combination of both types of cabin windows/port holes) among other interior appointments .... in accordance with the dictates of airline customization at the time of production. These variations resulted in B377-10-26 aircraft being operated by PAN AMERICAN (some of which were later modified with additional fuel capacity and then re-designated B377-10-26S/"SUPER STRATOCRUISER" ); B377-10-28 aircraft being ordered by SAS (delivered to BOAC after SAS cancelled its order); B377-10-29 aircraft being operated by AMERICAN OVERSEAS AIRLINES (later serving with PAN AMERICAN); B377-10-30 aircraft being operated by NORTHWEST AIRLINES); B377-10-32 aircraft being operated by BOAC (customized to the airlines own specific requirements); And B377-10-34 aircraft being operated by UNITED AIR LINES (later acquired by BOAC). Some originally PAX configured STRATOCRUISER aircraft were later converted to pure freighters .... re-designated B377-F aircraft.
By the late 1950's B377 STRATOCRUISER aircraft had almost disappeared from fleets among the principle US airlines .... although TRANSOCEAN AIRWAYS (whom aquired ex-BOAC aircraft) continued to operated the type until 1963.
During the 1960's a number of ex airline operated STRATOCRUISER aircraft, as well as ex military C-97 transports, were modified by AERO SPACELINES .... re-designated SUPER GUPPY (PREGNANT GUPPY), and MINI GUPPY aircraft .... intended for bulk and over-sized air cargo transportation. Some of these aircraft were also later upgraded with P&W and ALLISON type turboprop engines and subjected to further airframe modifications .... among which included swing-tails being incorporated into some aircraft to facilitate unrestricted rear-end loading .... particularly in regard to those aircraft used by NASA to transport components for the SATURN V rocket, and later, fuselage barrels and wing components for AIRBUS INDUSTRIE in Europe.
During the post-war and pre-1960's period DOUGLAS DC-6, DC-7, and LOCKHEED CONSTALLATION/STARLINER aircraft evolved to become the most popular of the worlds once great pounding piston powered propliner population .... among both US and foreign airlines alike .... "prior to" jetliners then entering service during the late 1950's and "RUINING EVERYTHING" .... as some prop-proud protagonists might possibly take pleasure in proclaiming
Mark C
AKL/NZ
"IMAGINE" .... it's 1958/59 come early 1960.
Buddy Holly, Ritchie Valens, and Big Bopper are "gone" .... but .... the music hasn't died completely because Elvis's now topping the charts along with Bill HAILEY & THE COMETS.
EISENHOWER's in the White House .... as the 34th US president.
The Korean war's over .... but the Cold War continues .... and Vietnam's not (officially) begun.
Despite failure of the British COMET 1 earlier during the decade jetliners are now acknowledged as being the future of world civil aviation.
BOEING, DOUGLAS, and CONVAIR/GENERAL DYNAMICS are each vying against one'another for a slice of the lucrative world market for first generation US-built 4-engine narrow-body civil jetliners .... whilst LOCKHEED has built "a turboprop" in the form of the L-188 ELECTRA .
Airports (and aerospace manufacturers) ready or not .... the civil Jet-Age has dawned and air transport, and the world, are about to be forever transformed.
Any number of the great pounding piston powered prop liners remain in service though .... progressively relegated to less prestigious routes or being disposed of by major operators (now re-equipping with jets), to be scrapped, or to embark upon new leases of life among smaller/less significant airlines. A few of the lucky ones will soldier on into the next millennium .... their big props flogging the air longer than most .... albeit that their glory days "are now over".
There's a new sound in the sky now as turbojet powered civil jetliners begin filling the skies with noise .... and smoke .... whilst also impressing the traveling public with their incredible performances (in comparison with that of smaller and slower prop liners among the previous generation of civil aircraft) and the new standards of comfort and service they afford.
The 1950's/60's era represented possibly "the greatest" period of change/advance ever witnessed within world civil aviation .... with aircraft/airlines transitioning from piston/radial engines driving big propellers, to turboprop, then turbojet engine power and fast narrow-body civil jetliners .... followed by the equally rapid transition to fanjet/turbofan power during the early 1960's, then big high-bipass ratio turbofan engines and the even larger 2nd generation series of wide-body civil jetliners by the early 1970's .... with the advent of A300B, B747, DC-10, and L-1011. All of which occurred within the relatively short space of less than a couple of decades.
In the USA .... civil aviation and development of progressively larger, more logistically capable, all-metal piston/radial powered aircraft had evolved rapidly throughout the 1930's and 1940's. By this period DOUGLAS had developed "the most respected" reputation among major aerospace manufactures around the world .... through development of its DC-1, DC-2, DC-3 family of prop liners, and was, by the early 1940's, about to launch its DC-4. During this same period LOCKHEED had also launched its smaller but successful L-10 ELECTRA and L-18 LOADSTAR series of proliners and was developing its pressurized EXCALIBUR .... whilst BOEING had responded to these challenges with its own B247 and pressurized B307 STRATOLINER aircraft.
Suddenly .... the future of US aviation development was interrupted and seemed to be thrown into disarray with Americas involvement with WW2 .... from December 1941. The development of civil aviation was suspended and almost entirely refocused upon design, and production, of military/combat type aircraft .... with almost all existing civil aircraft being impressed into war service whilst developing civil aviation projects were just as hastily re-engineered for military use. To this extent the DOUGLAS DC-3 and DC-4 became C-47 and C-54 transports respectively .... the BOEING B247 and B307 became the C-73 navigational trainer and C-75 transport respectively also .... whilst the LOCKHEED EXCALIBUR (which had by this time become the CONSTELLATION and had yet to fly) was re-designated as the C-69 transport .... each of which were impressed for military service roles.
Although civil aviation development would not be resumed (in earnest) until after 1945, Americas impressive mobilization effort during WW2 actually pathed the way for its future success and world conquest .... through experience gained from the organized and efficient mass production of aircraft, development of improved aviation infrastructure across the USA in order for larger aircraft types and increased traffic flow to be accommodated, and establishment of what later became the foundation for future civil air routes both across the USA and to abroad.
Considerations in regard to the future of US civil aviation were not entirely abandoned during wartime though .... especially when Howard HUGHES (accompanied by Jack FRYE), whom had been a driving force behind LOCKHEED development of the CONSTELLATION, flew an L-049/C-69 (# 43-10310), in TWA TRANSCONTINENTAL LINE livery, non-stop from Burbank/California to Washington DC, in just 6 hours 27 minutes (and 25 seconds) on April 17th 1944 .... in what was a spectacular achievement and publicity stunt, for the time (given the performance capabilities of comparable pre-wartime propliners and the continuing US war effort), and which also fore-shadowed the future of commercial air services within the USA.
After WW2 .... converted B17, B24, and even HALIFAX and LANCASTER bombers, served as interim commercial transports in various parts of the world. Whilst logistically capable these aircraft were entirely unsuitable for use as civil airliners though.
Originating during 1939 .... LOCKHEED development of its pressurized CONSTELLATION (like that of the DC-4) had been interrupted by WW2.
Consequently the prototype aircraft version (NX25600 .... with its up-scaled P-38 LIGHTING wing design and powered by 4X 2,200 HP R-3350 radial engines) did not fly until January 9th 1943 .... designated XC-69.
The USAAF had by this time placed orders for some 202X C-69 transports .... however .... only 22X of these airframes were produced, of which only 15X were ever delivered prior to the cessation of hostilities during 1945, and at which point the balance of this military order, for some 180X remaining airframes, were promptly cancelled. Those airframes already under construction, or planned for production, were then hastily converted for civil use .... re-designated L-049 CONSTELLATION aircraft.
Re-configured for up 60 PAX and powered by 4X 2,200 HP R-3350 radial engines, the civil L-049 first flew on July 12th 1945. TWA took delivery of the first aircraft on November 14th 1945 (followed by PAN AMERICAN WORLD AIRWAYS on January 6th 1946) .... and launched the first ever commercial CONSTELLATION service (operated by N86511/fleet # 555 "Star Of Paris") over its New York/La Guardia to Paris/Orly route (via Gandar/New Foundland and Shannon/Ireland .... over some 17 hours flying time) from February 5th 1946 .... followed by PAN AMERICAN WORLD AIRWAYS whom operated its first CONSTELLATION services over the airlines New York/La Guardia to Bermuda route from February 1946 also.
At this early stage of development LOCKHEED .... and its CONSTELLATION .... had an approximately 18 month lead over their DOUGLAS and BOEING competition.
The L-049's service entry was marred by a number of incidents/technical difficulties (cabin supercharger shaft fractures occurred causing hydraulic fluid to spray over engines from broken lines risking engine fires .... AND ..... arcing of through-studs that carried electrical current between the wings and pressurized fuselage .... each resulted in very early introductory problems), and at least one major accident, involving a TWA test flight on July 11th 1946, and which resulted in a 6 week grounding of the type from July 1946. Some 95 modifications were then applied to these aircraft prior to their being successfully returned to service. Some 88X L-049/C-69 airframes were produced by LOCKHEED between 1942 and 1946. A small number of civil L-049's were later modified with increased fuel capacity .... and re-designated L-149's.
The first exclusively civil production CONSTELLATION .... designated L-649 (registered NX101A) .... powered by 4X 2,500 HP R-3350 radial engines and based on the same fuselage as that of the preceding L-049 .... was intended for US domestic routes and first flew October 19th 1946. This heavier aircraft version entered service with EASTERN AIR LINES from May 1947. The L-649 also featured an optional detachable Speedpack utility/bin (below its central fuselage) to increase cargo capacity over short routes only .... for 3%/10 KT performance penalty. Some 16X L-649 airframes were produced by LOCKHEED between 1946 and 1951 .... of which 6X aircraft were produced as higher gross weight L-649A's (strengthened for additional fuel capacity and range) .... as delivered to CHICAGO & SOUTHERN AIR LINES from October 1950. A number of original L-649 airframes were also later upgraded to superior L-749 and L-749A specifications.
Production of the higher weight, long range, over-water CONSTALLATION series followed .... designated L-749 and L-749A .... also based on the L-049/-649 fuselage length (a few of these airframes were fitted with WX radar which resulted in a slightly lengthened nose) .... powered by 4X 2,500 HP R-3350 radial engines (fitted with Jet Stacks that enabling superior airspeed performance .... albeit with increased noise and which also exhibited significant flame effects too .... especially conspicuous during evening flights .... and to such an extent that it did occasionally disconcert unaccustomed PAX ). The L-749 first flew on March 14th 1947 .... with AIR FRANCE taking delivery of the first aircraft on April 18th 1947 .... followed by PAN AMERICAN WORLD AIRWAYS during June 1947, and with whom the type inaugurated the airlines around-the-world service (operated by NC86530 "Clipper America") also from June 1947. Development of the L-749 also coincided with a sizable military supply contract which later sustained the CONSTELLATION production line during a period of declining civil orders. What evolved from this renewed military interest was the heavier L-749A .... powered by 4X 2,700 HP "military standard" R-3350 radial engines with Curtis type electric propellers, minor engine nacelle modifications, and also featuring a strengthened fuselage and landing gear.
Further developed for commercial use .... SOUTH AFRICAN AIRWAYS took delivery of the first civil production L-749A during August 1950 .... followed by TWA. LOCKHEED also provided conversion kits to enable upgrades of former L-649 aircraft to superior L-749 specifications. Both L-749 and L-749A became the most numerous of CONSTELLATION type aircraft .... with some 113X civil airframes being produced by LOCKHEED between 1947 and 1951. A freighter version of the L-749A .... along with a turboprop powered L-749B .... were also proposed by LOCKHEED, but, cancelled due to insufficient interest and the unavailability of suitable power plants respectively.
During the post war Soviet imposed Berlin blockade ..... from June 24th 1948 until May 12th 1949 .... USAF C-69 transports flew some 6 million PAX miles, operating supply/relief flights between Westover AFB, Massachusetts, USA , to the UK, and on to Rhein-Main AFB, Frankfurt, in the then West Germany .... as part of the allied Berlin Airlift effort.
Production of the early/original CONSTELLATION series ceased from 1951 as, spurred-on by both TWA and competition from DOUGLAS .... LOCKHEED successfully evolved the aircraft's design into the larger, and even more logistically capable, L-1049 SUPER CONSTELLATION series that was to become regarded, by many, as the ultimate in prop liner development .... during this particular period.
To counter the DC-6 and DC-7 several versions of L-1049 SUPER CONSTELLATION aircraft were developed by LOCKHEED .... originally conceived during the early 1940's, but, suspended due to wartime priorities and the unavailability of suitable power plants at the time. The L-1049 incorporated more than 500 improvements/modifications over preceding L-049/649/749 aircraft versions .... among which included an 18 FT 4 IN fuselage stretch with re-designed rectangular cabin windows (as opposed to the circular cabin port holes of earlier production CONSTELLATION series aircraft) and larger cockpit windshields, strengthened landing gear, larger tri-tail surfaces, increased fuel capacity options .... for greater range, superior de-icing equipment, improved cabin heating efficiency and pressurization system comforts, along with more powerful engines too .... enabling progressively higher payload capabilities, performance, and endurance.
The first L-1049 was converted from the original CONSTELLATION prototype (re-registered NX6700). This aircraft first flew on October 13th 1950 .... powered by 4X P&W R-2800 radial engines. Some 24X initial production version L-1049 airframes were produced by LOCKHEED .... powered by 4X 2,700 HP R-3350 radial engines .... the "then" best powerplant available for "civil use", but, which also resulted in these aircraft being somewhat under-powered when operating at/near MGW.
Both civil L-1049A and -B aircraft were also produced by LOCKHEED .... along with military versions for both USAF-MATS and USN service roles. Some 330X CONSTELLATION type aircraft would eventually operate under numerous C-121, EC-121, JC-121, NC-121, TC-121, VC-121, YEC-121, PO-1W, R7V, and WV series designations. Early aircraft deliveries to the US military services were powered by 4X PRT equipped 3,250 HP "military standard" turbo-compound radial engines .... whilst later aircraft deliveries (most of the military inventory) were powered by 4X PRT equipped 3,400 HP "military standard" R-3350 turbo-compound radial engines.
A number of these aircraft were re-designated later during their military service after having been subject to various conversions for specific reconnaissance/surveillance and scientific research type roles. Military operated CONSTELLATION aircraft saw service during both the Korean and Vietnam conflicts .... some of which remained operational well into the 1970's.
Refitted with 4X 3,250 HP PRT equipped R-3350 turbo-compound radial engines (upon this power plant becoming available for "civil use") .... the L-1049C first flew on February 17th 1953 (registered PH-TFP). This aircraft entered service with KLM ROYAL DUTCH AIRLINES from August 1953, followed by AIR FRANCE, EASTERN AIR LINES, and TRANS CANADA AIRLINES .... and of which some 56X airframes were produced by LOCKHEED. TWA (by now a major CONSTELLATION operator) ordered, but, never took delivery of this particular version of the SUPER CONSTELLATION. The L-1049C featured improved cabin sound insulation and became the first of the "civil CONSTELLATION series" to be fitted with turbo-compound power plants .... which enabled both a superior ROC and higher cruising airspeed. Although still lacking DC-6B range, the L-1049C was otherwise comparable in performance, whilst also being capable of transporting greater payloads.
The L-1049D freighter followed .... and first flew during September 1954. This aircraft was essentially an L-1049C .... fitted with a strengthened floor and 2 forward and aft located port side main deck cargo doors. Only 4X of these airframes were ever produced by LOCKHEED .... specifically for SEABOARD & WESTERN AIRLINES .... and entered service with the airline during late 1954 (3X of which were leased to BOAC between 1955 and 1956 after the COMET 1 groundings) .... 2X of which were also later converted to superior L-1049H specification. At the time of its service entry the L-1049D was the worlds largest civil cargo aircraft.
The L-1049E CONSTELLATION represented a higher gross weight PAX configured version of the preceding L-1049D freighter .... of which some 18X airframes were produced by LOCKHEED. A number of original L-1049E orders were converted to the following and superior L-1049G specification prior to production.
Whilst the CONSTELLATION improved with each successive aircraft version, none of the established series were capable of flying non-stop transatlantic services .... from east to west .... against the prevailing meteorology. Even the earliest B707, COMET 4, and DC-8 jetliners were often similarly range impaired when operating to the US east coast from either European or UK ports .... imposing refueling/technical stops at either Shannon/Ireland, Keflavik/Iceland, or Gandar/New Foundland. Similar operational impositions applied to the DC-6B and DC-7B also.
Also based on the L-1049C airframe .... the L-1049F first flew flew during early 1955 and entered USAF-MATS service from August 1955 .... designated as the C-121C long range transport aircraft. This military version was equipped with wing tip fuel tanks, WX radar, and an APU .... whilst also featuring additional airframe strengthening in order to promote future conversion to turboprop power.
Between 1954 and 1955 4X aircraft, based on the R7V-1 airframe, were produced by LOCKHEED as prototypes for USAF and USN military air transport service roles .... originally designated L-1249A CONSTELLATION aircraft .... powered by 4X 5,500 BHP P&W YT34-P-12A turboprop engines with Hamilton Standard Hydromatic propellers, and capacity for 106 PAX or 73 stretcher cases. Featuring the same wing, fuselage, and landing gear strengthening applied to the military C-121C, the wingspan of these particular aircraft was shortened by 6FT 7IN, but, equipped with additional fuel capacity in the form of optional wing tip tanks. Re-designated R7V-2 .... this aircraft first flew on September 1st 1954 and was delivered to the USN on September 10th 1954 .... followed by USAF version .... re-designated YC-121F .... which first flew on April 5th 1955 and was delivered during July 1955. During flight testing these turboprop powered R7V-2 and YC-121F aircraft attained airspeed of some 415 MPH (479 MPH was actually achieved during a controlled 20* dive) .... to become "the worlds fastest transport aircraft" at the time. Civil versions of this turboprop development were also proposed by LOCKHEED .... re-designated L-1249B CONSTELLATION aircraft (based on the L-1049E fuselage) .... promising range in excess of 4,100 miles and London/Moscow, Los Angeles/Hawaii, and London/New York (via Gandar/Newfoundland) type services in 7 hours, 6 hours, and 9 hours respectively, but, little interest was expressed by civil operators whom, at the time, remained content with the performance their piston powered CONSTELLATION aircraft fleets. Beyond their relatively short USAF and USN military air transport service roles, the fuselage and tail sections of the only 4X R7V-2 and YC-121F aircraft ever produced by LOCKHEED, were used to construct composite civil L-1049G and L-1049H airframes. A single R7V-2 airframe was also later used to flight test the ALLISON 501-D turboprop engine, during LOCKHEED development of the L-188 ELECTRA, and prior to it being scrapped.
As competition between the CONSTELLATION and both DC-6B and DC-7 intensified .... LOCKHEED responded with L-1049G ("Super G") powered by 4X PRT equipped 3,400 HP R-3350 turbo-compound radial engines. Accommodating up to 95 PAX .... this aircraft could also be fitted with optional 1,037 gallon wingtip fuel tanks to extend range by more than 1,000 miles .... along with an optional WX radar unit that (when fitted) resulted in a 3 FT 2 IN nose extension .... and either Hamilton Standard or Curtis electric type propeller options .... among more than 100 other refinements over preceding SUPER CONSTELLATION aircraft versions. The L-1049G first flew on December 12th 1954 and entered service with NORTHWEST AIRLINES, and TWA, from 1955. Some 104X L-1049G airframes were produced by LOCKHEED .... among which included L-1049G/01 aircraft featuring a strengthened wing and permitting a slightly higher MTOW .... as delivered to REAL BRASIL and VARIG BRAZILLIAN AIRLINES from July 1955.
A convertible PAX/freight configured re-development of the L-1049G followed .... designated L10409H ("SUPER H") .... and which first flew on November 20th 1956. Based on the strengthened C-121C airframe .... this aircraft featured L-1049G improvements which promoted further increased payload capabilities with capacity for up to 120 PAX. Entering service with QANTAS AIRWAYS from December 1956 .... some 53X L-1049H airframes were produced by LOCKHEED. A number of earlier production SUPER CONSTELLATION aircraft were later upgraded to L-1049H specification. L-1049H aircraft were powered by 4X PRT equipped 3,400 HP R-3350 turbo-compound radial engines although some later production airframes ..... re-designated L-1049H/01 aircraft .... were powered by the EA series of these engines (also fitted to the later L-1649 STARLINER) with a higher METO rating and certified for a slightly higher MTOW .... as delivered to the FLYING TIGER LINE during 1957. 2X L-1049H/02 along with 2X L-1049H/07 designated aircraft were also produced by LOCKHEED .... featuring additional landing gear improvements.
Turboprop powered L-1049J versions of the SUPER CONSTELLATION (based on the established L-1049H fuselage, R7V-2 wing, and fitted with further increased fuel capacity) were also proposed by LOCKHEED, but, never produced for civil use.
By the mid 1950's, DOUGLAS and its long range DC-7C (by this time a year in advance of LOCKHEED development), were beginning to pose a major threat to the CONSTELLATION. LOCKHEED therefore sought to further enhance its established SUPER CONSTELLATION design. This resulted in the L-1649A STARLINER .... based on the same fuselage length (featuring a standard WX radar) as that of the L-1049 SUPER G .... for up to 99 PAX, a completely new/re-designed straight-tapered wing of increased span .... promoting greater fuel capacity .... and powered by 4X PRT equipped 3,400 HP R-3350 turbo-compound radial engines. This combination of modifications was intended to promote trans-Atlantic and trans-polar type range along with superior airspeed performance .... in order to counter the DC-7C. The prototype L-1649A STARLINER (registered N1649) first flew on October 11th 1956. This aircraft (the last of the CONSTELLATION series) commenced TWA "JESTREAM" services on the airlines trans-Atlantic routes between New York, London, Paris, and Frankfurt, from June 1st 1957 .... followed by trans-polar services between the US west coast and Europe. AIR FRANCE then introduced "SUPER STARLINER" Paris/Tokyo (via Anchorage), and Paris/Mexico City (via Montreal and Chicago) services from August 1957 .... followed by LUFTHANSA GERMAN AIRLINES operated "SUPER STAR" services between Dusseldorf, Frankfurt, Paris, and New York, from 1959 .... these being the only 3 airlines to ever order L-1649A aircraft from the LOCKHEED production line. Although the STARLINER version of the SUPER CONSTELLATION family represented "the pinnacle of propliner design" and offered superior range .... whilst also being slightly faster too .... its airspeed performance was little superior to that of the DC-7C. The higher cost of the L-1649A, and imminent introduction of trans-Atlantic jetliner services (from 1958), conspired to result in only 44X airframes ever being produced by LOCKHEED between 1956 and 1958 (the only stage of the CONSTELLATION production which lost money for LOCKHEED) .... all of which had been replaced by jetliners on trans-Atlantic services by 1961.
A small number of CONSTELLATION and STARLINER aircraft (including some original military airframes too) were later converted to freighters .... some of which continued to operate cargo services on behalf of less significant operators well into the 1970's .... and among which also included a small number of turboprop conversion od militat designated CONSTELLATION aircraft types. The last scheduled commercial CONSTELLATION services were operated by QUISQUEYANA DE AVIACION .... of the Dominican Republic .... during 1979 .... using what were, then, among the last remaining airworthy L-049's and L-749's in existence, on the airlines daily flights between Santo Domingo and San Juan.
The tri-tail serpantine silhouette of the CONSTELLATION and STARLINER have since been regarded, by many, as an aviation legend and possibly one of, if not "the most", elegant of aircraft designs ever produced.
The success of the C-54/R5D SKYMASTER (DC-4) as a military transport aircraft during WW2, and its post war popularity among airlines, became the foundation upon which DOUGLAS proposed to develop a larger and improved version of this particular aircraft .... in the form of the DC-6. Originally intended as a military transport the war had ended before this new aircraft type could enter USAAF service. This .... along with BOEING and LOCKHEED development of their respective pressurized B377 STRATOCRUISER and L-049/649/749 aircraft, also aimed at the rapidly growing post war US civil aviation market, prompted DOUGLAS to redevelop its DC-6 design for civil use in order to remain competitive.
The DC-6 retained the basic DC-4 wing design .... but .... incorporated a 6 FT 9 IN fuselage stretch and featured large square cabin windows (as opposed to circular cabin port holes of the DC-4), cabin pressurization, and a modified tail surface.
LOCKHEED production of the first L-049's having been reserved for Howard HUGHES/TWA imposed later than desirable delivery schedules for other prospective CONSTELLATION operators .... forcing AMERICAN AIRLINES, and UNITED AIR LINES, to negotiate with DOUGLAS .... and which resulted in AMERICAN AIRLINES then becoming launch customer for the DC-6 with an order for 50X aircraft. The civil DC-6 first flew on June 29th 1946 powered by 4X 2,100 HP R2800 radial engines .... although the original military intended prototype version of this aircraft had already flown (designated XC-112A .... later re-designated YC-112A) on February 15th 1946. Deliveries to AMERICAN AIRLINES, and UNITED AIR LINES, commenced from November 1946 .... with the first DC-6 services being operated by AMERICAN AIRLINES from April 1947.
This initial production aircraft was marketed in 2 different variants .... the DC-6-1156 version, powered by 4X 2,400 HP R2800 CA-15 radial engines (with water injection), and intended for short/medium type US domestic services with capacity for up to 68 PAX .... and the heavier DC-6-1159 version, powered by 4X 2,400 HP R2800 CB-16 radial engines (with water injection), equipped with additional fuel tanking and intended for longer over-water/transcontinental type services with capacity for up to 64 PAX. A series of inflight fires (including a fatal UNITED AIR LINES accident on October 24th 1947) marred the DC-6's service entry and which forced a 4 month grounding of the aircraft from late 1947. The cause of these incidents was eventually traced to fuel venting into the aircraft's cabin heating intakes. Once modified .... DC-6 services were successfully resumed from early 1948 and without similar occurrences. These aircraft were quickly proven to offer performance superior to that of the early CONSTELLATION series. Some 176X airframes .... of the initial DC-6 version .... were produced by DOUGLAS between 1946 and 1951.
In attempt to further better the CONSTELLATION, and appeal to the equally rapidly growing civil air freight market too, the DC-6A LIFTMASTER was developed by DOUGLAS. This was a pure freighter redevelopment the original aircraft design .... featuring a 5FT fuselage stretch (often devoid of PAX cabin windows) over that of the preceding DC-6 and with fore and aft located port side cargo doors, a strengthened floor .... and offering improved payload capabilities. The DC-6A first flew on September 29th 1949 .... powered by 2,400 HP R2800 CB-16 radial engines .... and entered service with SLICK AIRWAYS from April 1951.
Some 77X DC-6A airframes were produced by DOUGLAS .... the design of which, at the request of airline customers, was also later evolved into a convertible PAX/freighter version .... designated DC-6C .... and which could be configured for up to 77 PAX, or 13 tons of freight, or a combination of both. Some later production DC-6A aircraft were powered by 2,500 HP R2800 CB-17 radial engines, and number of original production aircraft were later converted to DC-6C specifications.
The DC-6A also appealed to the US military and resulted in orders for some 166X airframes .... designated C-118 LIFTMASTER in USAF service and R6D-1 in USN service (both of which saw service during the Korean conflict) .... along with a number of VC-118/A designated aircraft for presidential/VIP type service roles.
The commercial need to keep pace with/out-do LOCKHEED, and its CONSTELLATION, encouraged DOUGLAS to develop what then became the "ultimate" DC-6 aircraft .... in the form of the DC-6B .... featuring a further 1FT 1 IN fuselage stretch over that of the DC-6A/C and with capacity for up to 107 PAX. The DC-6B was once again marketed in 2 different variants .... the DC-6B-1198A version, powered by 4X 2,400 HP R2800 CB-16 radial engines (with water injection), intended for short/medium type US domestic services and with capacity for up to 89 PAX .... and the heavier DC-6B-1225A version, powered by 4X 2,500 HP R2800 CB-17 radial engines (with water injection), equipped with additional fuel tanking and intended for longer over-water/transcontinental type services with capacity for up to 89 PAX. Both aircraft were additionally marketed with either Hamilton Standard or Curtis electric type propeller options .... featuring a constant-speed reversible pitch. The DC-6B first flew on February 10th 1949 .... and entered service with UNITED AIRLINES from April 11th 1951 .... followed by AMERICAN AIRLINES from April 29th 1951 .... and PAN AMERICAN WORLD AIRWAYS from April 1952. Some 288X DC-6B airframes were produced by DOUGLAS between 1949 and 1958.
Despite arrival of B707 and DC-8 jetliners on the civil aviation scene from the late 1950's, DC-6's remained popular among major airlines around the world .... and well into the late 1960's. Many formerly PAX configured airframes were later converted to pure freighters .... including 2X swing tail DC-6B freighter conversions undertaken by SABENA BELGUIM WORLD AIRLINES .... re-desiginated DC-6B-ST aircraft. A small number of DC-6 aircraft were also later converted to water bombers and for aerial spraying type operations .... such as those operated by the French SECURITE CIVILE and Canada's CONAIR respectively. Some of these aircraft continued operating well into the 1990's.
The DC-6 .... particularly in DC-6B form .... became regarded as "one of" the finest, and most economic, of prop liners ever produced .... to such an extent that it even outlived the service of its larger and more powerful DC-7C counterpart.
Successful though the DC-6 was .... continued intense competition between DOUGLAS and LOCKHEED/the CONSTELLATION (along with BOEING and its B377 STRATOCUISER by this time also), spawned the development of larger and even more capable aircraft types .... spurred-on also by the airlines whom were seeking still greater range, capacity, and performance .... as both aircraft manufacturers, and civil operators, sought competitive edges.
When LOCKHEED announced its development of the turbo-compound powered L-1049C SUPER CONSTELLATION .... DOUGLAS, encouraged by AMERICAN AIRLINES support (payment of a pre-production order of 25 airframes), responded to this LOCKHEED threat by developing (what it anticipated would be) a larger and superior performance, similarly turbo-compound powered, version of its DC-6B .... in the form of the DC-7 .... featuring a 3 FT 4 IN fuselage stretch over that of the DC-6B with capacity for up to 95 PAX and retaining the DC-6B tail surface. The DC-7 first flew on May 18th 1953 powered by 4X PRT equipped 3,250 HP R3350 turbo-compound radial engines .... and entered service with AMERICAN AIRLINES from November 1953. Despite the new turbo-compound engines providing greater power .... service entry of the DC-7, and L-1049C also, were frustrated by a high incidence of engine failures resulting in diversions and schedule disruptions .... and which was believed (in part) to have been a consequence of competition between airlines, with some operators opting to maintain higher, than desirable, cruise power settings as a means of achieving faster/shorter point-to-point air times in an attempt to achieve competitive edges over one'anther. Some 102X airframes .... of the initial DC-7 version .... were produced by DOUGLAS from 1953 all of which entered service among the US carriers.
Production of the heavier DC-7B followed .... and which first flew on April 25th 1955, powered by 4X PRT equipped 3,250 HP R3350 turbo-compound radial engines. This aircraft .... some of which were equipped with engine nacelle saddle tank modifications/extensions to promote additional fuel capacity for increased range .... entered service with PAN AMERICAN WORLD AIRWAYS on June 13th 1955. Although the DC-7/B represented significant technical advances both aircraft versions struggled to meet their intended/designed range projections (non-stop trans-Pacific/trans-Atlantic/trans-polar type services being quite impractical even under the most favorable of circumstances) .... whilst also suffering excessive cabin vibration and noise impositions/discomforts than the preceding DC-6B. None-the-less .... some 111 DC-7B airframes were produced by DOUGLAS from 1955.
When jets began replacing props during from the late 1950's some DC-7B operators converted a number iof these airframes to pure freighters .... re-designated DC-7BF aircraft.
Committed to resolving the shortcomings of its DC-7/B series .... DOUGLAS embarked upon a major revision of the original aircraft design. This saw development of the DC-7C .... featuring a 3FT 4 IN fuselage stretch over that of the preceding DC-7/B with capacity for up to 105 PAX and a modified/lengthened tail surface. The aircraft's inboard wing chord sections were also each lengthened by 5 FT .... which re-positioned the engine nacelles further from away from the fuselage whilst increasing overall wingspan by 10 FT, promoting additional fuel capacity for greater range, and which also had the desirable effect of reducing cabin vibration and engine noise levels. These modifications, and greater power, combined to result in a 25% performance gain over that of preceding DC-7/B. The DC-7C first flew on December 20th 1955 powered by 4X PRT equipped 3,400 HP R3350 turbo-compound radial engines .... and entered service with PAN AMERICAN WORLD AIRWAYS on June 1st 1956. Given the aircraft's range improvements .... the name DC-7C was popularly corrupted to "SEVEN SEAS" .... implying there was no longer a ocean/sea body on the earths surface which these aircraft could not successfully traverse non-stop. Some 128X DC-7C airframes were produced by DOUGLAS between 1955 and 1958 .... exceeding production of the LOCKHEED L-1649A STARLINER (1 year behind DC-7 in its development) by a considerable margin, and far exceeding BOEING production of its B377 STRATOCRUISER, whilst not approaching anything like the sales success of its own preceding DC-6 counterpart .... however .... B707 and DC-8 jetliners were, by 1958, already entering service and beginning to conquer the worlds air routes in spectacular fashion, being met with favour by both airlines and the traveling public alike.
The DC-7 became the last in the line of famous DOUGLAS prop liner aircraft. A RR RYNE turboprop powered version of the DC-7 .... designated DC-7D .... was proposed by DOUGLAS, but, was not developed given the companies commitment to its DC-8 and the worlds new-found favour in the form of 1st generation narrow-body- civil jetliners. DC-7's remained in service throughout the 1960's .... with dwindling numbers continuing to operate (mostly as converted freighters) until the 1980's.
BOEING .... prior to WW2 .... had not been a conspicuously successful producer of civil aircraft, but, throughout the 1930's, was determined to establish a foothold within the rapidly developing US commercial aviation market. Though neither of its pre-war B247 and B307 STRATOLINER aircraft had realized spectacular production runs (in comparison with DOUGLAS DC-1/2/3/4 and LOCKHEED L-10/18 sales successes) .... albeit that prospects for the B307 were interrupted by military priorities during WW2 .... the substantial post war growth of commercial aviation within the USA, and around the world, was to change everything .... and quickly evolve .... as would the destiny of the BOEING company too as a result of new opportunities being promoted by this evolution.
The BOEING challenge to post-war DOUGLAS and LOCKHEED dominance in civil aviation was manifested in the form of its larger and more luxurious B377 STRATOCRUISER aircraft .... based on its military C-97 STRATOFREIGHTER design .... which had been developed from its B29 and B50 SUPERFORTRESS which had entered military service from 1944 .... and had also been evolved into the KC-97 STRATOTANKER.
Like the preceding C-97/KC97 .... the B377 featured a pressurized double-bubble fuselage configuration with capacity for up to 86 PAX, and which included a lower deck lounge/bar and PAX sleeping berths .... promoting unrivaled airborne luxury that (possibly) was not surpassed until the advent of 2nd generation civil jets in the form of wide-body B747, DC-10, and L-1011 TRISTAR during the early 1970's. Development of the B377 commenced from 1945 when BOEING company president Bill ALLEN authorized/risked the production of 50X airframes .... without a single customer pre-commitment. Any risk involved with this decision was (perhaps) minimized by the fact that any unsold airframes could, if necessary, be modified/re-adapted to military C-97/KC-97 freighter/tanker aircraft specifications.
Despite the aircrafts much higher unit cost, but, confident also in both the potential of this big new aircraft (based on known C-97 performance earlier during 1945), PAN AMERICAN WORLD AIRWAYS became launch customer for the B377 upon placing an order for 20 aircraft during November 1945 .... valued at some $25,000,000 (1945) and which became the, then, largest airline order in commercial aviation history.
The B377 STRATOCRUISER first flew on July 8th 1947 powered by 4X turbo-charger equipped 3,500 HP R4860 radial engines (unlike other propliner powerplants of the period .... as well as supporting what was regarded as the "fastest wing" of its time) .... and entered service with PAN AMERICAN WORLD AIRWAYS on September 7th 1948 on the airlines San Francisco/Honolulu route (later extended to Europe .... and and to the east .... as far afield as Beirut, Singapore, and Tokyo) .... followed by AMERICAN OVERSEAS AIRWAYS, and BOAC, on trans-Atlantic services between New York/London .... then NORTHWEST AIRLINES, and UNITED AIR LINES, over US trans-continental routes and services to Hawaii by early 1950.
These large aircraft were affectionately dubbed "The Ocean Liner Of The Skies" (this being a time when more PAX undertook trans-oceanic travel by sea rather than air) and may be regarded as the "jumbo" of their era .... the B377 STRATOCRUISER could be configured for up to 114 PAX in a high density seating configuration. Though large, fast, and unrivaled in the class of luxury it afforded, operating economics were not in the favor of these aircraft .... since the STRATOCRUISER was both a high-cost acquisition and expensive to operate. Being heavy it was also particularly airfield demanding and therefore restricted to the worlds largest airports only. For all its size/spaciousness and advanced engineering .... head-space on the B377 STRATOCRUISER was actually several inches less than that on the DC-4 which could, in a high density configuration, accommodate more PAX than most STRATOCRUISER aircraft were configured for, whilst also being considerably cheaper to operate. The aircrafts early reputation was also marred by the complexity and unreliability of its 26 cylinder P&W engines and Curtis Electric propeller combination .... which resulted in at least 2 major disasters among a number of other serious accidents/incidents throughout the 1950's.
Some 56X B377 STRATOCRUISER airframes were produced by BOEING between 1947 and 1950. These aircraft were produced under several designations .... each of which differed cosmetically in regard to their cabin window configurations (some aircraft featuring round, rectangular, or a combination of both types of cabin windows/port holes) among other interior appointments .... in accordance with the dictates of airline customization at the time of production. These variations resulted in B377-10-26 aircraft being operated by PAN AMERICAN (some of which were later modified with additional fuel capacity and then re-designated B377-10-26S/"SUPER STRATOCRUISER" ); B377-10-28 aircraft being ordered by SAS (delivered to BOAC after SAS cancelled its order); B377-10-29 aircraft being operated by AMERICAN OVERSEAS AIRLINES (later serving with PAN AMERICAN); B377-10-30 aircraft being operated by NORTHWEST AIRLINES); B377-10-32 aircraft being operated by BOAC (customized to the airlines own specific requirements); And B377-10-34 aircraft being operated by UNITED AIR LINES (later acquired by BOAC). Some originally PAX configured STRATOCRUISER aircraft were later converted to pure freighters .... re-designated B377-F aircraft.
By the late 1950's B377 STRATOCRUISER aircraft had almost disappeared from fleets among the principle US airlines .... although TRANSOCEAN AIRWAYS (whom aquired ex-BOAC aircraft) continued to operated the type until 1963.
During the 1960's a number of ex airline operated STRATOCRUISER aircraft, as well as ex military C-97 transports, were modified by AERO SPACELINES .... re-designated SUPER GUPPY (PREGNANT GUPPY), and MINI GUPPY aircraft .... intended for bulk and over-sized air cargo transportation. Some of these aircraft were also later upgraded with P&W and ALLISON type turboprop engines and subjected to further airframe modifications .... among which included swing-tails being incorporated into some aircraft to facilitate unrestricted rear-end loading .... particularly in regard to those aircraft used by NASA to transport components for the SATURN V rocket, and later, fuselage barrels and wing components for AIRBUS INDUSTRIE in Europe.
During the post-war and pre-1960's period DOUGLAS DC-6, DC-7, and LOCKHEED CONSTALLATION/STARLINER aircraft evolved to become the most popular of the worlds once great pounding piston powered propliner population .... among both US and foreign airlines alike .... "prior to" jetliners then entering service during the late 1950's and "RUINING EVERYTHING" .... as some prop-proud protagonists might possibly take pleasure in proclaiming
Mark C
AKL/NZ