Traveling to Birmingham, Alabama, and the Barber Museum’s new Advanced Design Center, I met with Pierre Terblanche. The former Ducati design specialist described what he has tried to perform in his new prototype, modeled solely (save for its wheel rims) by 3D printing.
Terblanche’s thesis is that, regardless of spectacular technological advances within the three a long time since he designed Ducati’s Supermono, these advances—and far frequent sense moreover—have failed to look in new motorbike design.
To consider his concepts he has constructed a non-running however full-scale prototype, a New Supermono if you’ll, whose elements emerged from the Barber Design Center’s massive HP 3D printer, principally in a nylon materials. While working in CAD is fast, nothing stimulates the thoughts like a full-scale 3D object, the very motive conventional styling growth used clay and wooden. The 3D printer provides accuracy, pace, and the power to retailer the executions digitally.
Motorcycles Have Become Too Big
Terblanche’s first basic remark is that bikes are too huge; they’ve grown out of human scale. Electric lifts within the heart show two bikes: the unique 1992 Supermono and Pierre’s new prototype, each powered by inside combustion (IC) engines with a single horizontal cylinder. The authentic’s 549cc engine makes 75 hp unsupercharged; the brand new bike with its Rotrex supercharger “makes” 137 hp, sufficient to achieve present power-to-weight ranges whereas retaining the dimensions of the nimble authentic. In four-wheeled autos the development has been to make use of smaller, lower-friction, and due to this fact extra fuel-efficient engines, and to take care of their energy degree at market expectation by way of turbocharging. The method may assist bikes to fulfill future fuel-consumption laws as effectively, if it comes.
Radiators Are Too Big, Too
Terblanche’s second huge change is to eradicate the large, ineffective water and oil radiators utilized by in the present day’s highly effective bikes, situated as they’re instantly behind the entrance wheel like a sail from a square-rigged ship. To permit the fascinating ahead engine place, in the present day’s rads are tightly up in opposition to the entrance of the engine, complicating hot-air outflow. Using wind-tunnel knowledge, Terblanche cites measurements of air velocity on the rear floor of such coolers, displaying that top circulation exists in solely a small circle at higher heart plus a slim vertical strip at every edge. This illustrates that a lot of such radiator space is nonfunctional. To treatment that he has designed the brand new bike’s chassis as a front-to-rear duct with the coolers mounted within the center.
Air enters on both aspect of the steering head on the entrance and is easily decelerated by widening the passages till they unite on the coolers. Once by way of the radiators, the heated air is accelerated by way of a nozzle to exit on the rear, into an space of usually low stress. The single exhaust pipe exits close by; this presents the potential of utilizing exhaust momentum to pump air by way of the duct even at low automobile speeds. (Such exhaust pumping was used to maneuver cooling air on the 1947 Convair CV-240 airliner and 1958 DHC-4 Caribou military-transport plane.) Aerodynamic drag outcomes when larger stress exists on the entrance surfaces of a automobile than on the rear, so feeding the outflow from the coolers into the low stress behind this prototype motorbike can scale back drag.
This shouldn’t be a brand new thought. Important World War II fight plane such because the British de Havilland Mosquito and North American Mustang employed such ducted coolers for the aim of eliminating cooling drag and even producing a slight web thrust. How? Such ducted radiators are literally low-grade jet engines, taking in cool air, increasing it by including warmth power, leading to an outflow velocity larger than influx velocity. To study extra, Google the Meredith impact.
Parts of this idea have appeared on racing bikes, resembling these of the late John Britten and on at the very least one of many Kenny Roberts Team two-stroke 500 triples of the late Nineties, putting the radiator horizontally beneath the rider’s seat however not trying to reaccelerate the downward-emerging scorching air.
Aerodynamics and Closing the Wake
Engineers know that bikes have drag coefficients (Cd) which are scandalously excessive—approximating these of a field truck. The Cd of a given form roughly compares its drag with that of a flat plate, perpendicular to circulation, having the identical frontal space. Motorcycles have two drawback areas: 1) as a result of they’re brief they’re chopped off behind the rider, making a turbulent wake that carries away vital power, and a couple of) the uncovered entrance wheel, fork, and brake meeting creates turbulent circulation that streams previous the decrease half of the automobile, including to wake turbulence and drag.
For an instance of a great low-drag form, take into account a fish resembling tuna or salmon: Their surfaces are easy and uninterrupted, and their most cross part is ahead, permitting an extended tapering tail that easily closes the fish’s wake behind it with minimal turbulence loss. In 1968, a wonderful fairing was developed within the Caltech wind tunnel for Harley-Davidson’s vintage side-valve KR roadracer. This additionally had its largest cross part effectively ahead, and its sides tapered inward to the rear. How many occasions have I, strolling by way of race paddocks, seen fairings mounted in “snowplow” style, changing into wider to the rear, enlarging the wake and creating further drag? I recall the remarks of an aerodynamicist good friend who had simply returned from Bonneville: “Many of the shapes I saw out there would’ve gone faster backward.”
Subsonic Shapes for Subsonic Speeds
Terblanche’s prototype has the easily rounded nostril that produces lowest drag at subsonic speeds. Because wind-tunnel work reveals that airflow behind the rider is separated and turbulent, this bike has no “streamlined” seatback. The bodywork surfaces are easy, contrasting with many present sportbike fairings, that are made up of many separate parts or “shingles.”
Rationalizing the Suspension
Terblanche has lengthy questioned why the trade continues to position the entrance suspension items contained in the fork tubes, relatively than utilizing a single central unit that’s 1) inexpensive, 2) simply accessible/replaceable, and three) supplies damping and ride-height changes in a single location.
With present-day inverted forks, the one connection between the 2 sliding members is the axle. Even in the present day, a wobble or passing over bumpy pavement whereas leaned over can tilt the entrance wheel, knocking brake pads again sufficient that the lever comes again to the bar on the subsequent nook. Terblanche’s model of the telescopic fork due to this fact supplies two joined parallel and cylindrical tubes, carried by the steering-head bearings, and resembling a bicycle’s fork (Y-shaped). Moving up and down upon the tubes are a pair of sliders joined by a strong arch excessive of the entrance tire and by the entrance axle (no extra front-wheel tilting and no extra pad knock-off). The decrease finish of the only entrance suspension unit attaches to the highest of this arch. The fork tubes include no damping equipment or oil; they’re simply guides to outline the entrance wheel’s motion. He proposes additional that the information tubes be made in smaller-than-usual diameter so that they disturb as little airflow as potential over the steered meeting. Their stiffness? A little bit of arm-waving right here; maybe reliance upon inside bracing.
In addition to this restricted streamlining of the fork itself, the perimeters of the decrease fairing have moved outward, offering a floor for airflow streaming previous the entrance wheel to connect itself relatively than persevering with again as a turbulent free stream.
In motion, Terblanche’s design is similar to a standard telescopic fork. Why not one of many different entrance ends folks persist in calling “high tech”? Why not fixed wheelbase or fixed path designs? Because such options haven’t demonstrated superior efficiency.
Simplicity and Reduced Parts Counts
When Terblanche designed the Ducati 999, his temporary was to simplify. He asks why fashionable bikes have electrical techniques with tangles of wires working all over the place. Shouldn’t many of the “wire” be in a single place, within the type of a number of printed circuit boards (PCBs)? Shouldn’t the alternator and voltage regulator be built-in right into a single-wire system? The extra elements there are, situated throughout a motorbike, the extra time-consuming meeting and repair turn out to be. Wasn’t single-wire CAN bus supposed to finish tangles by integrating coded switches into every single-wire shopper of energy, all messaged by a central unit?
This prototype has its electronics (battery, PCBs, ignition, ECU) connected to the entrance of the alternator, situated on the left.
Ease of Access
Having seen race-team mechanics crowded round their bikes, every one looking for to take care of his specialty, Terblanche proposes two extra simplifications. First is a single jack level low on the engine crankcase. A two-pronged lever elevate engages matching holes, permitting the entire bike to rise 20mm away from the bottom for wheel modifications. Second, electronics entry is positioned on the left aspect of the machine and suspension entry on the best. Additional entry is offered by the hinged seat, ahead higher fairing, and the dummy “tank.”
Comprehensive Adjustability
Because the “rider triangle” of bars, seat, and pegs is particular person to every particular person, shouldn’t all be simply and rapidly adjustable? Accordingly, windscreen top, tank longitudinal place, and pegs are readily movable.
High Performance from a Simple Engine
How can a 699cc engine ship 130-odd horsepower? A Rotrex centrifugal compressor and the plenum chamber wanted to mediate between the compressor’s regular circulation and the engine’s consumption pulsing are situated ahead close to the engine’s horizontal cylinder. Fewer elements and centralization of capabilities translate to decrease construct price and higher affordability, a development we see within the current reputation of parallel-twin engines.
It was energizing and thrilling to spend time with an skilled practising designer with particular concepts. What comes subsequent?
Source: www.cycleworld.com