Theme : Aerodynamics – Buttresses, A User Guide

Driven To Write attempts to decipher an aerodynamic staple but finds the going surprisingly turbulent.

york cathedral
Flying buttresses on York Cathedral. Image unknown.

In architectural terms, a buttress is defined as a structural member built against or projecting from a wall serving as a support or reinforcement. They were more prevalent at a period when structural engineering was more of a naive art, employed as a support against sideways forces. As architect’s skills developed, the need for buttressing decreased, latterly viewed as something of an admission of failure, much like an air dam or spoiler in automotive terms. There are several types of architectural buttresses, the most visually spectacular probably being the ‘flying buttress’, a structural device used in the design of many Gothic cathedrals.

The buttress as applied to vehicle design is usually a structural rear quarter pillar which not only supports the roof of the vehicle, but can also act as an aerodynamic aid to stabilise the airflow at a notably turbulent point of the body. Here it gets a little confusing, because in some instances, they were not employed as structural elements and in others, where employed, it was to little or no aerodynamic purpose. As in architecture, so also in car design. As technology and aerodynamic theory evolved, the requirement for buttresses has diminished. However, Pininfarina continue to employ them as a form of house style.

The one-off Pininfarina bodied Ferrari 375 MM Speciale
1954 Pininfarina bodied Ferrari 375 MM Speciale. Image: Wheelsage

Perhaps the earliest instance of this feature dates as far back as the early 1950’s. In Italy, the styling houses of Bertone and Pininfarina began a period of aerodynamic research, possibly in response to that of Bristol, Jaguar and Lotus who were at the vanguard of research on these shores. While the American motor industry also pursued aerodynamic theory, they chose to apply it as a styling conceit to satisfy a public hungry for aerospace iconography.

In 1954, Pininfarina created a special one-off Ferrari 375 MM for film director, Roberto Rossellini. He commissioned a unique and shockingly modern bodystyle. For its time, it was incredibly futuristic, featuring concealed headlights, a very low penetrating nose and winged fairings aft of the rear screen, sweeping back toward the rear. It was like nothing that had been seen before but was dismissed as little more than a curiosity. However, Pininfarina‘s engineers stored the idea away and would return to it the following decade.

marcos

Buttresses reappeared on Frank Costin’s revolutionary and stylistically divisive 1959 Marcos, but with the car’s appearance proving too much for some, it was again ignored. Costin would reprise the effect on his eponymous Amigo model a decade later.

As mid-engined sports racing cars began to proliferate, it became necessary to find a means of bridging the abrupt cut-off of the rear portion of the roof panel and the rear deck and engine cover. This posed both a styling and aerodynamic challenge. There is evidence to suggest legendary Italian stylist, Giorgetto Giugiaro first applied the buttress to a mid-engined design for his 1964 Lamborghini concept – a car that some suggest, represents the genesis of the mythical Miura. Pininfarina themselves followed shortly afterwards utilising what they referred to as ‘fin shaped rear uprights’ on the mid-engined 250 LM. Later Pininfarina concepts adopted a more integrated treatment, culminating in the appearance of the production Ferrari 206 Dino in 1968.

Pininfarina again - the 330 GTC Speciale from 1967
Pininfarina again – the 330 GTC Speciale from 1967. Image: Fantasyjunction

By the late 1960’s, the buttress had become one of those stylistic shorthand’s beloved of cynical manufacturers – signifying speed and mid-engined glamour. Naturally, this aesthetic would find its way across the Atlantic and soon Detroit was awash with Pontiac GTO’s, Dodge Chargers and Mercury Cougars, all of whom featured what the US manufacturers referred to as ‘Tunnel-Backs’. Even Ford’s European satellite got in on the act, the 1969 Capri featuring ‘tunnelback’ elements aft of the C-pillar. None of these arrangements had any serious aerodynamic purpose, they simply referenced Italian exotica, suggesting raw performance and sex-appeal and that was enough for some.

2771_1968_Dodge_Charger_rear
Image: Dodgecharger.com

Perhaps the best known and stylistically controversial buttresses of all are those attached to the rear three quarters of the 1975 Jaguar XJ-S. Designer, Malcolm Sayer referred to them as ‘Sail Panels’, incorporating an inward twist to aid aerodynamic spillage. Misunderstood by contemporary opinion-formers, they existed for sound aerodynamic and aesthetic reasons.

1456
Jaguar XJ-S sail panel

Despite the varied nomenclature used to describe these features, they can all be grouped together under the umbrella term of buttresses. However, lazy journalists often refer to them as ‘flying buttresses’, which if one is to apply a strictly architectural definition – (and really we should) – is technically and factually incorrect.

Because architecturally speaking, a buttress must be entirely in contact with the structure it supports. A flying buttress on the other hand, is in contact with the structure at only one point.

2007-ferrari-599gtb-fiorano-flying-buttress-photo-37784-s-1280x782
Ferrari 599 Fiorano rear three-quarter flying buttress

Applying this rule to motor vehicle design, only a handful of production designs could reasonably lay claim to the term; cars such as the Ferrari 599 GTB, and Honda’s 2015 NSX being latter-day examples of the breed.

But if peak flying buttress is your wont, you must look to Giugiaro’s 1973 Maserati Merak. Here, they serve as uprights; a visual element to fool the eye into believing the roofline continues beyond the rear screen.

Maserati Merak - photo via karakullakeblog.com
Flying buttresses on a Maserati Merak – photo: karakullakeblog.com

But that’s not entirely accurate either, because in actuality, these aren’t really buttresses at all, since they serve no structural or aerodynamic purpose whatsoever. Buttresses: More complicated than you might imagine…

Author: Eóin Doyle

Founding Editor. Content Provider.

6 thoughts on “Theme : Aerodynamics – Buttresses, A User Guide”

  1. The just-released Ford GT also displays these addenda and the i8 too of sorts. The more recent uses of them is claimed to be properly aerodynamic or even thermodynamic. From an early point in time I have felt that the C6 gives the impression of having flying buttresses, but doesn’t. It’s the crisp, flat trailing edge of the rear pillar which is met by the concave – when viewed externally – rear window that fools the eye somewhat. I like the effect as it accentuates the abnormality of that rear screen and a very different vista to every other car of the modern era. Doubtless someone will point out something that does not work about the arrangement, but it works for me.

  2. I do wonder if these features (as SV mentions above) are actually intended to be buttresses or something else altogether. Of course, not everything featured in my article are in fact buttresses – it does appear to be a fairly broad church – if you excuse the pun. SV, you mention the C6’s rear window treatment – something that has been reprised on Audi’s Prologue concept – giving it a similar appearance of buttresses.

    1. I had not looked that closely at the Prologue, so had not noticed. This is awkward, as I have always felt that the C6 had strong Audi (A6) elements to it, so the convergence seems likely to become more pronounced.

  3. The inventor of these “butresses” is the designer/architect of the magnificent Hagia sophia; Isıdoros from Miletos…

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