• A history of porpoising

    Skirted ground-effect Formula 1 cars of the late 1970s and early 1980s were occasionally afflicted by a type of instability referred to as ‘porpoising’. Many cars suffered, but the phenomenon is nicely described in Peter Wright in relation to the development of the Lotus T80:

    “The car was so sensitive that, above a certain critical speed, it became aerodynamically unstable in pitch. One test day at Silverstone, Mario Andretti coined the term ‘porpoising’ to describe the phenomenon when he observed daylight under the front wheels while at speed on the straight.

    “Since 1977 I had been working with David Williams, Head of the Flight Instrumentation Department at the Cranfield College of Aeronautics. He had designed and built a digital data system for use on the T78 when it had become apparent that it would be absolutely essential to gather data from the chassis in order to progress with the development of ground effect. When the T80 porpoising started, I discussed the phenomenon with him, and he offered to model it and validate the results with the data we had. He established that it was an aero-elasticity problem, akin to flutter in an aircraft wing. The changing aerodynamic loads, as the car bounced and pitched, excited the pitch and heave modes of the sprung mass on its springs and tires.” (Formula 1 Technology, p36 and p308.)

    However, pace Wright, the same phenomenon had already been identified and named at least as early as the 1940s, albeit in the field of seaplane hydrodynamics; specifically, during the take-off and landing of such craft. A Wartime Report issued by NACA in June 1943, begins:

    “Porpoising is a self-sustaining oscillatory motion in the vertical longitudinal plane…Observations of porpoising show that there are two principal oscillatory motions (1) a vertical oscillation of the center of gravity and (2) an angular oscillation about the center of gravity. These two motions are seen to have the same period but to differ in phase.” (Some systematic model experiments on the porpoising characteristics of flying-boat hulls, Kenneth S.M. Davidson and F.W.S. Locke Jr, p7).

    The British were also heavily involved in the early study of porpoising, an Aeronautical Research Council report in 1954 defining the phenomenon as follows:

    “Porpoising, basically, consists of a combination of oscillations in pitch and heave. It includes both stable and unstable oscillations, a stable oscillation being one which damps out. (A review of porpoising instability of seaplanes, A.G.Smith and H.G.White, p5).

    All of which is an important reminder that ground-effect was of crucial importance to hydroplanes long before Formula 1 happened upon the phenomenon.


  • Flatmobile – Lowest Car in the World

    Here is the lowest car in the world! This cool car is officially recognised by the Guinness World Records for lowest street legal car, the Flatmobile stands at just 19 inch or 48 cm tall.

    The car is rear mounted with a 875cc engine for propulsion. Obviously inspired from Batmobile, Perry Watkins from England is the proud owner of the FlatMobile.

    Technical Specifications

    • Donor car -1963 Hillman Imp
    • 30″ height sectioned out from body
    • Ground clearance -2″
    • Height-19″
    • Length-12′2″
    • Width-5′ 5″
    • Combustion Engine-Hillman Imp 875 Sport
    • Jet engine-DIY gas turbine
    • Suspension rear-Standard springs and shocks on rear but cut down
    • Suspension front-Avro shocks with adjustable height 4″ springs
    • Wheels-Cosmic alloys 10×6J
    • Tyres-Goodyear Eagles 205 x 50 x 10

    Here is a video of the Flatcar in action:

    Continue Reading…

  • Cars Of The FA Cup Stars

    The FA Cup semi-finals 2015 to be played this weekend will by no means be the most thrilling stage of this year’s competition. Current holders Arsenal take on Championship side Reading in the first match (Saturday, 18th April) before Liverpool face a rejuvenated, but still relegation-threatened, Aston Villa in Sunday’s tie.

    The bookies are (naturally) expecting an Arsenal vs Liverpool final, which would fall on May 30th – the birthday of retiring captain Steven Gerrard. However, despite Tim Sherwood’s claims that the FA Cup is “unimportant” compared to top flight survival, he would surely like to crown a first season at Villa Park with silverware.

    The good news is however that the semi-finals will boast a lot of players with excellent taste in cars. For this article, where we examine the supercars of footballing millionaires, we are indebted to Liverpool for knocking out Blackburn Rovers in their 6th round replay; as this article would be somewhat shorter had they progressed instead!

    Arsenal – Ferrari 458

    The Ferrari 458 seems to have become the “team car” of Gunners players, with at least three known to own one including Mesut Ozil, Theo Walcott and Jack Wilshere. The 448 Speciale has a top speed of 202 MPH and will achieve 0-60 in 3.0 seconds – enough to even leave the notoriously pacy Walcott gobsmacked!

    What’s more, the 458 is simply a beautiful machine; its bodywork so sculpted and aerodynamically perfect you might worry about being sliced by the car’s wake if it passed too quickly.

    While we can’t understand why seemingly the entire Arsenal 1st team squad would plump for the same supercar, we concede they’ve made a fine choice.

    Gabby Agbonlahor (Aston Villa) – Lamborghini Gallardo

    The 458 may scream style, but the Gallardo puts out an altogether different vibe – raw power. Lamborghini’s best ever selling car will hit 100km/h in 3.6 seconds and look damn fine whilst doing so.

    All footballers everywhere: Range Rover Sport

    Many decry the Range Rover as an obnoxious accessory owned by crass vulgarians. I happen to disagree. For one, what car do you own if you’re excessively rich but incapable of controlling a supercar – step up the Range Rover. Also, you’d feel a lot more comfortable navigating hordes of paparazzi if your vehicle were built like a light battle tank.

    Glen Johnson (Liverpool) – Aston Martin DB9

    The DB9 is understated British excellence wrapped up in a beautifully sleek cocoon. The perfect car then for Liverpool right-back Glen Johnson whose excellent performances for club and country are overlooked more often than not.

    Honourable mention: Mark Wright (Liverpool) – Volkswagen Passat Estate

    The era of “mega money” football may have started with the Sky TV deal in 2002, but don’t let anyone fool you into thinking footballers were poorly off before then. In the early 1990s the Anfield parking ground would fill with Porsches, Mercedes and Land Rovers – with the addition of a particularly ugly estate car.

    Some assumed the beaten up Volkswagen Passat belonged to a cleaner, but it was actually the property of Liverpool defender Mark Wright, who treasured it for years.

    Though envy is a natural reaction to the incredible lives footballers lead, Wright gains a lot of kudos for showing you don’t need to splash the cash to be taken seriously!

    Continue Reading…

  • Adrian Newey and the bar-headed goose

    The April edition of Motorsport Magazine contains a fabulous F1 season preview from Mark Hughes, which includes the news that Adrian Newey has recently been taking a break in the Himalayas.

    Now, whilst it’s likely that the principal purpose of this expedition was to enlighten the Dalai Lama on the importance of using large-eddy simulation to understand the interaction of brake-duct winglets with the spat vortex, it’s also possible that Adrian was drawn by the legendary bi-annual migration of the bar-headed goose.

    These birds are amongst the highest-flying in the world, and travel across the Himalayas in a single day. William Bryant Logan claims in Air: Restless Shaper of the World (2012), that “the bar-headed goose has been recorded at altitudes of over thirty-three thousand feet. This is the altitude where your pilot remarks that the outside temperature is 40 degrees below zero, where the great fast-flowing rivers of the jet streams set weather systems spinning. The air here contains only one-fifth of the oxygen near sea-level, where the goose winters in lowland India wetlands and marshes. Yet in the space of a few hours the bird can fly from the wetlands to the top of the high peaks and then out onto the world’s largest high plateau. There are lower passes through the mountains, but the goose does not take them. It may even preferentially go higher.”
    However, research led by Bangor University tracked the bar-headed geese with GPS as they migrated over the Himalayas, and reached the following conclusion in 2011:

    “Data reveal that they do not normally fly higher than 6,300 m elevation, flying through the Himalayan passes rather than over the peaks of the mountains…It has also been long believed that bar-headed geese use jet stream tail winds to facilitate their flight across the Himalaya. Surprisingly, latest research has shown that despite the prevalence of predictable tail winds that blow up the Himalayas (in the same direction of travel as the geese), bar-headed geese spurn the winds, waiting for them to die down overnight, when they then undertake the greatest rates of climbing flight ever recorded for a bird, and sustain these climbs rates for hours on end.”

    Furthermore, The roller-coaster flight strategy of bar-headed geese conserves energy during Himalayan migration, (Science, 2015), suggests that “geese opt repeatedly to shed hard-won altitude only subsequently to regain height later in the same flight. An example of this tactic can be seen in a 15.2-hour section of a 17-hour flight in which, after an initial climb to 3200 m, the goose followed an undulating profile involving a total ascent of 6340 m with a total descent of 4950 m for a net altitude gain of only 1390 m. Revealingly, calculations show that steadily ascending in a straight line would have increased the journey cost by around 8%. As even horizontal flapping flight is relatively expensive, the increase in energy consumption due to occasional climbs is not as important as the effect of reducing the general costs of flying by seeking higher-density air at lower altitudes.

    “When traversing mountainous areas, a terrain tracking strategy or flying in the cool of the night can reduce the cost of flight in bar-headed geese through exposure to higher air density. Ground-hugging flight may also confer additional advantages including maximizing the potential of any available updrafts of air, reduced exposure to crosswinds and headwinds, greater safety through improved ground visibility, and increased landing opportunities. The atmospheric challenges encountered at the very highest altitudes, coupled with the need for near-maximal physical performance in such conditions, likely explains why bar-headed geese rarely fly close to their altitude ceiling, typically remaining below 6000 m.”