Bubbletop

Bubbletop (pronounced buhb-uhl-top)

(1) In aircraft design, a design of pilot’s canopy (originally military slang for what designers dubbed the “bubble canopy”, a Perspex molding which afforded exceptional outward visibility).

(2) An automobile using a transparent structure over the passenger compartment, replacing the usual combination of roof & windows.

(3) A descriptor of certain automobiles of the early 1960s, based on the shape rather than the method of construction, the conventional metal and glass used.

1940s: The construct was bubble +‎ top.  Bubble dates from the late fourteenth century and was from the Middle English noun bobel which may have been from the Middle Dutch bubbel & bobbel and/or the Low German bubbel (bubble) and Middle Low German verb bubbele, all thought to be of echoic origin.  The related forms include the Swedish bubbla (bubble), the Danish boble (bubble) and the Dutch bobble.  Top pre-dates 1000 and was from the Middle English top, toppe & tope (top, highest part; summit; crest; tassel, tuft; (spinning) top, ball; a tuft or ball at the highest point of anything), and the Old English top & toppa (top, summit, tuft of hair), from the Proto-West Germanic topp, from the Proto-Germanic tuppaz (braid, pigtail, end), of unknown origin.  It was cognate with the Old Norse toppr (top), the Scots tap (top), the North Frisian top, tap & tup (top), the Saterland Frisian Top (top), the West Frisian top (top), the Dutch top (top, summit, peak), the Low German Topp (top), the German Zopf (braid, pigtail, plait, top), the Swedish topp (top, peak, summit, tip) and the Icelandic toppur (top).  Alternative forms are common; bubble-top in automotive & aeronautical engineering and bubble top in fashion.  Bubbletop is a noun and bubbletopped is an adjective; the noun plural is bubbletops.

Evolution of the Mustang's bubbletop: P-51C (top), P-51 III (centre) and P-51D (bottom).

“Bubbletop” began as World War II (1939-1945) era military slang for officially was described as the “bubble canopy”, the transparent structure sitting atop the cockpit of fighter aircraft, the advantages being (1) superior visibility (the purest interpretation of the design affording an unobstructed, 360° field-of-view, (2) improved aerodynamics, (3) easier cockpit ingress & egress (of some significance to pilots force to parachute and (4), weight reduction (in some cases).  Bubbletops had been seen on drawing boards in the early days of aviation and some were built during World War I (1914-1918) but it was the advent of Perspex and the development of industrial techniques suitable for the creation of large, variably-curved moldings which made mass-production practical.  The best known early implementations were those added to existing air-frames including the Supermarine Spitfire, Republic P-47 Thunderbolt and North American P-51 Mustang.  By 1943, the concept had become the default choice for fighter aircraft and the technology was applied also to similar apparatuses used elsewhere on the fuselage where they were styled usually as “blisters”.  In the post war years it extended to other types, most dramatically in the Bell 47 helicopter where the cabin was almost spherical, some 70% of the structure clear Perspex.

The enormous and rapid advances in wartime aeronautics profoundly influenced designers in many fields and nowhere was that more obvious than in the cars which began to appear in the US during the 1950s.  Elements drawn variously from aeronautics and ballistics did appear in the first generation of genuinely new post-war models (most of what was offered between 1945-1948 being barely revised versions of the 1942 lines) but it was in the next decade the designers were able to embrace the jet-age (a phrase which before it referred to the mass-market jet-airline travel made possible by the Boeing 707 (which entered commercial service in 1958) was an allusion to military aircraft, machines which during the Cold War were a frequent sight in popular culture).  On motif the designers couldn’t resist was the bubble canopy, something which never caught on in mass-production although Perspex roofed cars were briefly offered before word of their unsuitability for use in direct sunlight became legion.

GM Firebird XP-21 (Firebird I, 1953).

Not content with borrowing the odd element from aircraft, the General Motors (GM) team decided the best way to test which concepts were adaptable from sky to road was to “put wheels on a jet aircraft” and although they didn’t do that literally, by 1953 when Firebird XP-21 was first displayed, it certainly looked as though it was exactly that.  Its other novelty was it was powered by a gas turbine engine, the first time a major manufacturer in the US had built such a thing although a number of inventors had produced their own one-offs.  When the XP-21 (re-named Firebird I for the show circuit) made its debut, some in the press referred to it as a “prototype” but GM never envisaged it as the basis for a production car, being impractical for any purpose other than component-testing; it should thus be thought of as a “test-bed”.  The bubble canopy looked as if it could have come from a US Air Force (UFAF) fighter jet and would have contributed to the aerodynamically efficiency, the 370 hp (280 kW), fibreglass-bodied Firebird I said to be capable of achieving 200 mph (320 km/h) although it’s believed this number came from slide-rule calculations and was never tested.  Despite that, in its day the Firebird II made quite a splash and a depiction of it sits atop the trophy (named after the car’s designer, Harley Earl (1893–1969), the long time head of GM’s styling studio) presented each year to the winner of NASCAR’s (National Association for Stock Car Auto Racing) premiere event, the Daytona 500.

GM Firebird II (1956).

Compared with its predecessor, the Firebird II (1956), rendered this time in titanium was almost restrained, the Perspex canopy a multi-part structure over a passenger compartment designed to seat “a family of four”.  The family might have chosen to drive mostly in darkness because the heat build-up under the midday sun would have tested the “individually-controlled air conditioning”, a system upon which comfort depended because the Perspex sections were fixed; there were no opening “windows”.  Still, even if hot, the family would have got places fast because the same 200 mph capability was claimed.

GM Firebird III (1958).

The Firebird III was displayed at the 1958 Motorama and although GM never built any car quite like it, within a season, elements of it did begin to appear on regular production models in showrooms (notably the rear skegs which Cadillac used for a couple of years) and some of its features are today standard equipment in even quite modest vehicles.  The striking “double bubbletop” never made the assembly lines although some race cars have at least partially implemented the concept.  What proved more of a harbinger was the specification, the Firebird III fitted with anti-lock brakes, cruise control, air conditioning, an automated “accident avoidance system” and instead of a steering wheel, the driver controlled the thing with a joystick, installed in a centrally-mounted “Unicontrol & Instrument Panel”.  All these were analogue-era electro-mechanical devices too bulky, fragile or expensive for mass production, wider adoption in the decades to come made possible by integrated circuits (IC) and micro-processors.

1959 Cadillac Cyclone (XP-74).

Borrowing from the Firebird II, Cadillac also used a bubble top for the Cyclone (XP-74) concept car which in 1959 toured the show circuit.  Although it was powered by the corporation’s standard 390 cubic inch (6.5 litre) V8, there was some adventurous engineering including a rear-mounted automatic transaxle and independent rear suspension (using swing axles, something not as bad as it sounds given the grip of tyres at the time) but few dwelt long on such things, their attention grabbed by features such as the bubble top (this time silver coated for UV (ultra violet) protection) which opened automatically in conjunction with the electrically operated sliding doors.  The Perspex bubble canopies from fighter aircraft never caught on for road or race cars but so aerodynamically efficient was the shape it found several niches.

1953 Ferrari F166MM Spider by Vignale (left) and 1968 MGCGT (centre & right).

Bubbles often appeared atop the hood (bonnet) to provide clearance for components inconveniently tall.  Most were centrally located (there was the occasional symmetrical pair) but the when BMH (British Motor Holdings, the old  BMC (British Motor Corporation) shoehorned their big, heavy straight-six into the MGB (1963-1980), it wouldn’t fit under the bonnet, the problem not the cylinder head but the tall radiator so the usual solution of a “bonnet bulge” was used.  However, for that to clear the forward carburetor, the bulge would have been absurdly high so a small bubble was added.  It probably annoyed some there wasn’t a matching (fake) one on the other side but it’s part of the MGC’s charm, a quality which for years most found elusive although it’s now more appreciated.  For MGC owners wish to shed some weight or for MGB owners who like the look, the “bonnet with bubble” is now available in fibreglass.

The winning Ford GT40 Mark IV (J-Car) with bubble to the right, Le Mans 1967 (left) and the after-market (for replicas) “Gurney Bubble”) (right).

US racing driver Dan Gurney (1931–2018) stood 6' 4" (1.9 m) tall which could be accommodated in most sports cars and certainly on Formula One but when he came to drive the Ford GT40 Mark IV it was found he simply didn’t fit when wearing his crash helmet.  The original GT40 (1964) gained its name from the height being 40 inches (1016 mm) but Mark IV (the “J-Car”, 1966) was lower still at 39.4 inches (1,000 mm).  Gurney was the tallest ever to drive the GT40 and the solution sounds brutish but fix was effected elegantly, a “bubble added to the roof to clear the helmet.  Gurney and AJ Foyt (b 1935) drove the GT40 to victory in the 1967 Le Mans 24-hour endurance classic and the protrusion clearly didn’t compromise straight-line speed, the pair clocked at 213 mph (343 km’h), on the famous 3.6-mile Mulsanne Straight (which was a uninterrupted 3.6 miles (5.8 km) until the Fédération Internationale de l'Automobile (the FIA; the International Automobile Federation and world sport’s dopiest regulatory body) imposed two “chicanes”),  Known ever since as the “Gurney Bubble”, such is the appeal that they’re now available for any GT40 replica: Like the AC Shelby Cobra, the GT40 “reproduction” industry is active and there are many times more of these than there are survivors of 105 originals.

Ferrari 250 GT “Tour de France” LWB Berlinettas by Zagato: The “double bubble” roof (left), the Hofmeister kink (centre) and the famous “Z” kink, (right).

The Italian coachbuilding house Zagato was founded in 1919 by Ugo Zagato (1890-1968) and since the early post-war years, their designs have sometimes been polarizing (the phrase “acquired taste” sometimes seen), their angularity often contrasted with the lines of other, notably Pinninfarina and Bertone but unlike many which have over the years folded, Zagato remains active still.  One Zagato design never criticized was his run in 1956 of five Ferrari 250 GT “Tour de France” LWB Berlinettas, memorable also for introducing the signature “Zagato double-bubble roof.  The roof was practical in that it better accommodated taller occupants but it really was a visual trick and a variation on the trick Mercedes-Benz used on the “Pagoda” (W113; 230, 250 & 280 SL; 1963-1971) which they explained by saying “We didn’t lower the roof, we rained the windows”.  The other famous feature (which appeared on only one) was the fetching “Z” shape on the rear pillar, replacing the “Hofmeister kink” used on some others.

1962 Chevrolet Impala “bubbletop” Sport Coupe (left), 1963 Ford Consul Capri (centre) and 1972 BMW 3.0CS (E9, right).

The 1959 Chevrolet quickly came to be nicknamed “bubbletop” and the style spread, both within GM and beyond.  The “bubbletop” reference was to the canopy on aircraft like the P-51D Mustang but was an allusion to the shape, not the materials used; on cars things were done in traditional glass and metal.  Across the Atlantic, Ford in the UK applied the idea to their Consul Capri (1961-1964), a two-door hardtop which the company wanted to be thought of as a “co-respondent's” car (ie the sort of rakish design which would appeal to the sort of chap who slept with other men’s wives. later to be named as “co-respondent” in divorce proceedings).  The Capri was a marketplace failure and the styling was at the time much criticized but it’s now valued as a period piece.  Chevrolet abandoned the look on the full-size cars after 1963 but it was revived for the second series Corvair (1965-1969).  A fine implementation was achieved in the roofline of the BMW E9 (1968-1975) which remains the company’s finest hour.

The bubble shirt and bubble tops.

The bubble skirt (worn by Lindsay Lohan (centre)) is one of those garments which seems never to quite die, although there are many who wish it would.  Once (or for an unfortunate generation, twice) every fashion cycle (typically 10-12 years), the industry does one of its "pushes" and bubble skirts show up in the high street, encouraged sometimes by the odd catwalk appearance; it will happen again.  While the dreaded bubble skirt is easily identifiable, the “bubble top” is less defined but there seem to be two variations: (1) a top with a “bubble skirt-like” appendage gathering unhappily just above the hips (left) and (2) a kind of “boob tube” which, instead of being tightly fitted is topped with an additional layer of material, loosely gathered.  The advantages of the latter (which may be thought of as a “boob bubble” are that it can (1) without any additional devices create the illusion of a fuller bust and (2) allow a strapless bra to be worn, something visually difficult with most boob tubes because the underwear’s outline is obvious under the tight material.