{"id":9668,"date":"2015-02-20T20:51:46","date_gmt":"2015-02-21T03:51:46","guid":{"rendered":"http:\/\/cafe.foundation\/blog\/?p=9668"},"modified":"2015-02-20T20:52:22","modified_gmt":"2015-02-21T03:52:22","slug":"new-zero-powerplants","status":"publish","type":"post","link":"http:\/\/cafe.foundation\/blog\/new-zero-powerplants\/","title":{"rendered":"Motorcycle Motors as Powerplants for Experimenters"},"content":{"rendered":"

A frustration borne by homebuilt aircraft designers for years has been that of finding an appropriate, reasonably-priced powerplant for aircraft in the single and small two-seat range.\u00a0 \u00a0\u00a0Early experimenters often converted motorcycle engines to their ultralight needs.\u00a0 Continentals, Lycomings, and Franklins filled those needs in the 1930s and \u201840s, and other than Rotax and a few smaller manufacturer\u2019s offerings, there really haven\u2019t been any replacements since then.\u00a0 Electric powerplants, however, can be found in the motorcycles being produced by many American and foreign companies now, with more to come from Europe and Japan.<\/p>\n

\"Les<\/a>

Les Long’s Harlequin engine used two customer-supplied Harley Davidson pistons, cylinders, heads and rods. Long supplied crankcase, new crankshaft and camshaft for Depression-era $98<\/p><\/div>\n

Designers looking for available electric motors and \u201cplug-and-play\u201d* complete systems may want to look at the 2015 Zero Motorcycle lineup<\/a>.\u00a0 Since one Zero motor has flown at the Arlington, Washington Fly-in and at AirVenture 2013, we can attest to the demonstrated performance.\u00a0 Zero\u2019s newer model motors, controllers, and batteries can be found on the latest bikes from the company.<\/p>\n

Their specifications are certainly indicative of light weight and high performance.\u00a0 The least powerful unit in the Zero FX produces a maximum of 44 horsepower with 70 foot-pounds of torque, enough to accelerate this reasonably light bike from zero to 60 in only 4.0 seconds \u2013 within the range of an \u201caverage\u201d Tesla S sedan.\u00a0 Since torque translates to the ability to twist a large propeller, this capability speaks airplane language.<\/p>\n

Some of the lightness comes from the 20-pound \u201caircraft-grade aluminum\u201d frame.\u00a0 Even the largest and most powerful motorcycle in their range has a 23-pound frame.\u00a0 The complete bike without rider weighs 289 pounds and can carry a 341-pound load, or 630 pounds total.<\/p>\n

Your editor called Ryan Biffard of Zero to find out how much the components weigh.\u00a0 He generously shared the following:<\/p>\n

He notes that Zero does not allow sales of components for aircraft, an understandable reaction in these litigious times.\u00a0 To save Zero and other companies any heartburn in this area, some have suggested buying a complete motorcycle, stripping the necessary parts and selling the remaining bits to recoup part of the cost.\u00a0 Another hint \u2013 contact a friendly dealer who can sell you replacement parts.<\/p>\n

\"Zero<\/a>

Zero 75-7 motor weighs only 38 pounds (compared to Long’s 80 pounds). It produces twice the horsepower<\/p><\/div>\n

Ryan says \u201cEach 2.5 kWh (nominal) battery module weighs 40lbs (give or take), so a 10kWh battery (one with 4 modules in it) weighs around 160lbs.\u00a0 Each module has its own built-in battery management system (BMS).\u00a0 This is roughly what Mark Beirele has in the cockpit behind the pilot seat in his e-Gull.<\/p>\n

A triple \u201cmonolith\u201d consists of three of the 2.5 kWh modules and weighs around 120 pounds.\u00a0 Mark is flying with the equivalent of a quad \u201cmonolith.\u201d<\/p>\n

Motors come in two sizes.\u00a0 The 75-7 weighs about 38 pounds (jibing with Mark\u2019s numbers) and can climb at 40 kilowatts (54 hp.) for one minute, 30 kW (40 hp.) for several minutes, and cruise at 20 kW (27 hp.) indefinitely.<\/p>\n

The 75-5 weighs about 30 pounds and can climb at 30 kW for one minute, 20 kW for several minutes, and cruise at 14 kW (18.8 hp.).<\/p>\n

As Mark Bierele points out, though, the motors run at high speeds and thus need a reduction gear of some sort which adds cost and weight.<\/p>\n

Ryan says the Sevcon Gen4 Size4 motor controller for the power numbers listed above weighs around seven pounds.\u00a0\u00a0 If less power is desired the Size2 can be used: it would save a few pounds, and is a little bit cheaper.<\/p>\n

Now for the bad news.\u00a0 Buying the complete bike is a bit pricey, but consider what you\u2019re getting.\u00a0 Besides the motor and controller, the battery management system and all the appropriate wiring harnesses, you get a battery pack which is essentially a refillable \u201cgas tank\u201d with the cost equivalent of about one cent per mile.\u00a0\u00a0 If Zero is correct on its lifetime expectations, that \u201ctank\u201d could last from from 158,000 miles for the largest battery pack on the smallest motorcycle to over 450,000 miles for the largest pack on the highest-performance model.<\/p>\n

Zero\u2019s web site lists the prices for their bikes from under $10,000 to a little over $20,000.\u00a0 Compared to 40-to-57-horsepower gasoline engines and the costs for induction and exhaust systems, the motors and controllers are comparable, and it could be argued that the batteries are far more economical than even today\u2019s cheap gas fill-ups.<\/p>\n

Other manufacturers offer comparable equipment with comparable specifications, but the Zero motors have actually flown and demonstrated their aerial capability.\u00a0 At this point, use of any electric motorcycle power system is still highly experimental and subject to some risk.\u00a0 That\u2019s what experimenters have been facing for centuries, and gladly accepting the challenge.<\/p>\n

*\u201cPlug-and-play\u201d should be taken only as a term describing pre-engineered systems that would be adaptable to a project.\u00a0 Plugs become too easily unplugged in severe conditions.\u00a0 One should follow proven practices in connecting electrical components \u2013 practices which usually involve more structurally sound fastenings.<\/p>\n