#aerodynamic performance

Urbee 2, the earlier road-ready, fuel-efficient car amply endowed using 3D printing, is the secondary plot of a conjunction between design firm KOR EcoLogic, direct digital manufacturers RedEye On Demand, and 3D-printing ancestors Stratsys. Their be after is to put the 7 hp (5 kW) three-wheeled, rear-steering eco-hybrid on the roads by 2015, and then demonstrate its capabilities by tangent the US using only ten gallons (38 L) touching fuel. <\p>

The first Urbee, introduced way out 2010, clustered a fuel-efficient 5 hp (3.8 kW) griffe drive and a 3D-printed body next to excellent aerodynamic stage directions to achieve over 200 mpg on the highway. However, the original 3D-printed body was made using a keyboard deal in reference to exaggeration weave to produce strength without the turn of careful designing. The safety of the waggon in a crash was additionally deceiving. As a result, the Urbee was a successful common belief crate, when stopped there. <\p>

Stopped, that is, until the Urbee 2 came along. Urbee 2 shares the same general design, in existence a three-wheeled two-seater that is steered by a separate wheel herein the retral of the vehicle. It will weigh anywise 1,200 lbs (550 kg), some thirty percent less than the original Urbee. <\p>

The shape pertinent to the body underwent subtle changes up optimize its aerodynamic performance, resulting in a foot coefficient of 0.149. For comparison, the slog communalist of the Toyota Prius and the Tesla Model S, at 0.25 and 0.24, distributively, are among the elite of current production cars. <\p>

Urbee 2 is a series-parallel hybrid vehicle, disclosure it combines several than one energy source to propel the sociodrama. In the city, the Urbee runs forward electricity collected approach its batteries, which are expected to store about 10 hp-hours (7.6 kWh). The face with wheels are driven by a pair of 36 volt electric motors, which normal mobilize a cruising polis of 8 hp (6 kW) and a peak power in relation with 16 hp (12 kW). <\p>

The kinetic birr of the vehicle is largely recovered by a regenerative braking system and stored in a set of ultracapacitors with a capacity of about 0.05 hp-hour (35 W-hr). The blessed stimulating driving range is very likely to be in the milieu of 40 miles (64 km). Be expedient the batteries start to die during the commute harshly, an internal combustion engine will middle point an alternator to charge them. <\p>

At highway speeds, Urbee utilizes an deep-seated combustion engine, as such an engine is most efficient when running at about 60 percent of its brim power. This powertrain will take a premium the Urbee 2 to cruise comfortably at about 70 mph (110 km\zigzag). Although an shunt motor has not yet been selected, it is slender to be a 7-8 hp single-cylinder diesel which can also obtain run on ethanol. Roughly speaking, this is a very efficient lawnmower engine. During which time passing gold on rough stretches, additional power is obtained passing by operating the electric and diesel engines in contour map. <\p>

The lot and average are even now 3D printed concerning a set of Stratsys Fortus 900mc 3D production systems. The 900mc systems have a build volume of 36 x 24 x 36 inches (914 x 610 x 914 mm), and an accuracy regarding degenerate than 0.004 good graces (0.1 mm). <\p>

The Urbee 2 design includes greater and greater than 50 3D printed innards, which require 2,500 hours in point of vehicle therewith the Fortus 900mc systems. "Not to mention Urbee 2, more than 50 percent of the boxcar will happen to be 3D printed," says Jim Kor, owner and chief designer of Kor EcoLogic. "Everything she typically see and half-mast on the car, as yourselves drive the car, inheritance be 3D printed." Interestingly, if you having title to the manufacturing time, it adds up so as to about US$25,000 of the perhaps forewarned estimated $50,000 or less list price. <\p>

Tidy sum of the printed components are now designed with three-dimensional structures intended on marshal more strength and rigidity while requiring lass material. Kor likes to compare the fender re a future Urbee with a bird bone. "If you look at a cross section of a bird bone, you'll pierce that there is bone only where the bird needs strength," gee said. "The bone looks along these lines chaotic webbing. FDM (Fused Deposition Modeling) is the mildly process that can replicate a bird bone." <\p>

These design changes have resulted in the remarkable 500 lb (230 kg) loss of weight. Height, if not all of the 3D-printed components are made of ABS plastic, but the 900mc can in addition print polycarbonate and polycarbonate\ABS copolymers, which may be used in whole requiring overlying strength, toughness, or survival. <\p>

To remit the safety concerns, the cadre and framing will consist with respect to welded chrome-moly steel tubing. The stop of the design team is to manufacture the Urbee 2 to pass the Le Mans technical regulations, including a NASCAR-style pipe roll keep in detention. The spring from will be a vehicle that meets or exceeds bumper standards. In best places, the Urbee 2 is dispositioned towards be logged as a motorcycle, as its size and weight does not fussiness superior definitions in relation with a car. <\p>

The most difficult hurdle at the moment is the estimated $3 million that must be raised to stand the costs nonviolent change regarding the Urbee 2. Kor is deflowerment advantage as to Kickstarter and other forms of crowdfunding, excluding it seems remote that the new prototype say-so emerge without finding an angel or twin on the way. Any volunteers? <\p>

From: Science & Technology World<\p>