{"id":10222,"date":"2015-07-31T15:01:03","date_gmt":"2015-07-31T22:01:03","guid":{"rendered":"http:\/\/cafe.foundation\/blog\/?p=10222"},"modified":"2015-07-31T15:01:03","modified_gmt":"2015-07-31T22:01:03","slug":"smartflyer-electric-four-seater","status":"publish","type":"post","link":"http:\/\/cafe.foundation\/blog\/smartflyer-electric-four-seater\/","title":{"rendered":"SmartFlyer \u2013 an Electric Four-Seater?"},"content":{"rendered":"

The people behind the Smartflyer, a Swiss design concept<\/a> now under development ask, \u201cWhy does the Smartflyer look like this?\u00a0 With a tail-mounted electric motor, it\u2019s a bit reminiscent of e-Genius, and also a bit like a strutless Rutan Skigull.\u00a0 In fact, the basic configuration has been used on many significant aircraft over the last several decades, as a segment of Smartflyer\u2019s web site<\/a> shows.<\/p>\n

\"Smartflyer<\/a>

Smartflyer shows more than a passing resemblance to e-Genius, Rutan Skigull, others<\/p><\/div>\n

As Herr\u00a0Professor\u00a0Dipl-Ing.\u00a0Rudolf\u00a0Voit-Nitschmann, Project Leader on e-Genius explained<\/a>, several benefits accrue from this arrangement of aerodynamic elements.<\/p>\n

    \n
  1. Compared to a conventional touring motor glider a substantial larger propeller-diameter can be realized without a high and consequentially heavier undercarriage. Therefore the propeller-efficiency will increase.<\/em><\/li>\n
  2. The front body part has the aerodynamic quality of a modern glider (no vorticities and local impact pressure peaks) and thus a very small drag.<\/em><\/li>\n
  3. The propeller is optimally protected from ground contact.<\/em><\/li>\n<\/ol>\n
    \"Renderings<\/a>

    Renderings show a short tricycle landing gear, high wing and even higher propeller<\/p><\/div>\n

    Electric motors are light enough to mount on a tail and are therefore able to benefit from that placement while only blowing over part of the vertical fin and rudder.\u00a0 Compare this to a nose-mounted propeller on a conventional aircraft, which imposes prop-wash on every part of the fuselage, much of the wing, and most of the tail surfaces.<\/p>\n

    The Smartflyer designers are concerned with the wing-fuselage intersection, a point of \u201cdelicate\u201d tuning for many sailplane designers.\u00a0 A good design can have excellent wings and a well-honed fuselage shaped to slice through the air, but sometimes putting these together can create much greater drag than the combination of drag for the separate elements.<\/p>\n

    \"Munich<\/a>

    Munich Akaflieg MU-31 reduces number of places where wing intersects with fuselage, provides full-span lift distribution<\/p><\/div>\n

    Smartflyer intends applying findings by the Akaflieg Munchen to craft \u201can ideal transition of wing and fuselage with a turbulent airfoil in the wingroot part.\u201d\u00a0 The Munich University design for their MU31 sailplane<\/a> is an attempt to lower interference drag in the critical wing-fuselage intersection.\u00a0 Placement of the wing gives uninterrupted lift distribution across the entire wing, including the center section, and makes for only two points of interference drag instead of the usual two where the wing \u201cplugs into\u201d the fuselage.<\/p>\n

    Following e-Genius\u2019s motor placement and the MU-31\u2019s wing position, Smartflyer developers hope to achieve \u201can [extraordinarily] efficient aircraft with low emissions and low energy consumption. Energy costs are about one third of the total costs of the operating costs.\u201d Savings in energy use would grow in the future with a reduction in battery costs and improvements in their performance.<\/p>\n

    At first, the airplane will have a 20-30 kilogram (44-66 pound) motor, augmented with an unspecified internal combustion engine.\u00a0 Smartflyer claims, \u201cThe electric motor is the best power plant for aviation, in particular for light aircraft where a turbine is too expensive.\u201d<\/p>\n

    According to its web site, \u201cSmartflyer is optimized for a comfortable and most economic cruise. Today’s batteries are not sufficient for longer flights but the capacity is increasing every year of development. To compensate the insufficient battery capacity the Smartflyer is equipped with a range extender which is a two-cylinder four-stroke piston engine. A generator is coupled to the piston engine and charges the batteries.\u00a0The range extender is a modern high efficient piston engine but not certified for aviation. The main power system is the electric motor and the energy source of the batteries.\u201d<\/p>\n

    \"Smartflyer<\/a>

    Smartflyer in its element, cruising quietly in a most economical way<\/p><\/div>\n

    To help long cruises go smoothly, Smartflyer mounts a center-mounted sidestick with a secondary stick easily mounted for a second pilot. \u00a0Switches on the sticks control the electric elevator and aileron trim.<\/p>\n

    It is easy to picture some of the power components used in the Equator P2 or a larger version of those in the hybrid-powered e-Genius.\u00a0 A small ICE reduces battery weight, leading to the possibility of actually carrying four in an electric airplane.<\/p>\n

    Smartflyer claims flying in the four-seat cabin will be \u201cpure pleasure\u201d with a sound level like that of a car and visibility unobstructed by an engine or wing above or below the passenger area.\u00a0 Since the airplane has no flaps for takeoff or landing, maneuvering is simplified, with \u201cone operation less to think about or to be the source of false manipulation.\u201d\u00a0 Simplicity is good, but your editor would like some numbers to show an average pilot can manage those all-important operations.<\/p>\n

    Motor and propeller control as described should be similar to using a FADEC system in a conventional aircraft.\u00a0 According to Smartflyer, \u201cA computer compares the desired thrust with the actual torque on the propeller and the actual airspeed. The computer sends a signal to the variable pitch control and sets the optimum pitch for the actual conditions.\u201d\u00a0Software safeguards prevent unwanted responses from the motor, even if a pilot moves the throttle too quickly, for instance.<\/p>\n

    Smartflyer is a product of IG Electric Aircraft<\/a>, established on April 1, 2015, set up as an association under Swiss law.\u00a0 The group hopes to create a \u201cproof-of-concept\u201d vehicle, including the construction and operation of a prototype under the project name, \u201cSmart Cards.\u201d\u00a0 The association hopes this will provide the basis for certification of an electrically-powered airplane.\u00a0 They will award contracts to third parties to \u201cfulfill the association’s purpose,\u201d coordinate efforts of \u201clike-minded organizations and individuals,\u201d and share \u201cdeveloped and accumulated knowledge\u201d with chosen beneficiaries.<\/p>\n

    President Rolf Stuber and board members Felix Jenni and Peter Stuber drafted a set of statutes <\/a>(in German)\u00a0to guide their work and are working with qualified suppliers to begin this major project.\u00a0 We hope to see reality growing from the great-looking renderings that show their hoped-for airplane.<\/p>\n