{"id":6338,"date":"2012-07-21T08:14:59","date_gmt":"2012-07-21T15:14:59","guid":{"rendered":"http:\/\/cafe.foundation\/blog\/?p=6338"},"modified":"2012-07-21T08:14:59","modified_gmt":"2012-07-21T15:14:59","slug":"emg-5-electric-motorglider","status":"publish","type":"post","link":"http:\/\/cafe.foundation\/blog\/emg-5-electric-motorglider\/","title":{"rendered":"EMG-5 Electric Motorglider"},"content":{"rendered":"

This isn\u2019t Brian Carpenter\u2019s first time at the small airplane rodeo.\u00a0 He\u2019s built at least a dozen aircraft, designed several from scratch, and even entertained the hosts of TV\u2019s Mythbusters series with a series of rides in his team\u2019s ultralights.<\/p>\n

His latest creation at Tangent Aircraft is a sleek Part 103 ultralight<\/a> that seems to break or bend the rules on several fronts, presenting a twin-pivoting-motored, Fowler-flapped, retractable-gear craft that would seem to be too complex to fall into legal 103 status \u2013 or even into something the average novice private pilot would be allowed to fly.\u00a0 The 36-foot span and 105-square-foot wing would seem too fast to meet stall limits.<\/p>\n

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EMG-5 with vectored motors, Fowler flaps deflected<\/p><\/div>\n

Carpenter explained his design philosophy to your editor a few days ago, and he said the greatest challenge of meeting part 103 regulations was attaining the stall speed requirement with the small wing area.\u00a0 Normal, unflapped ultralights need about 140 square feet to meet the 27.6 mph stall speed.\u00a0 The Fowler flaps manage to lower the speed, but while causing extreme pitching moments on the small craft.\u00a0 To help counter that, Carpenter pivots the two Plettenberg Predator 37 motors<\/a>, which give downthrust to the nose and help short takeoff performance.<\/p>\n

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Plettenberg Predator motor with spinner, propeller and mount, weighing in at less than 5.5 pounds<\/p><\/div>\n

He also points out that for demonstration of the airplane\u2019s flight characteristics, \u201cInitially we will only have to demonstrate that the aircraft is capable of flying at these speeds. There is no requirement that the aircraft actually be operated during normal operations in this configuration.\u201d<\/p>\n

This may seem like parsing the jots and tittles of the law, but many \u201cheavy\u201d ultralights skated over these very issues with no harm and no foul called.<\/p>\n

Though very different in approaches, it is instructive to compare Carpenter\u2019s EMG-5 with Dale Kramer\u2019s Lazair ultralight <\/a>converted to Joby Motor power <\/a>and amphibious operation.\u00a0 Both airplanes use 100 pounds of lithium batteries and are powered by twin electric motors putting out around 15 kilowatts.\u00a0 Both have all-metal structures, with the exception of the foam ribs in the Lazair and some carbon fiber fairings on the EMG-5.\u00a0 Both, with careful analysis and interpretation of what the rules actually say, fly within Part 103 constraints.<\/p>\n

The Plettenbergs are \u201coutrunners\u201d meaning the rotor spins about the central stator, which is mounted to the arm that pivots from each side of the nose of the aircraft.\u00a0 Each motor\u2019s propeller is mounted to the spinning rotor, with motor and propeller hub covered by a streamlined spinner. \u00a0Electric connections come though the stator\u2019s hub.<\/p>\n

Each motor is capable of producing 99 pounds of thrust, helping the ultralight\u2019s short takeoff and landing characteristics.<\/p>\n

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Diagram of pitch control with vectored thrust, Fowler flaps<\/p><\/div>\n

Construction pictures on the web site detail the carefully-thought out design, especially the swiss-cheese-like structure surround the prone pilot\u2019s position.\u00a0 This is no problem for Carpenter, who is a hang-glider pilot and accustomed to fly that way.\u00a0 The airplane includes windows in the bottom of the fuselage to allow views straight down, and the visibility forward and to the sides will be obstructed only by the pilot\u2019s helmet. \u00a0A ballistic parachute will bring the whole airplane down safely in an emergency, allowing the prone pilot to stayh in the protective roll cage.<\/p>\n

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Swiss-cheese look of roll cage over prone pilot position<\/p><\/div>\n

The airplane can be towed aloft with a car, with motors used as sustainers for short gliding flights.\u00a0 This would allow smaller, lighter battery packs.\u00a0 A customer could expand battery capabilities as finances allowed and end up with a fully-charged airplane that could fly over one-and-a-half hours on a complete battery pack.\u00a0 Aero tows are also possible, giving the EMG-5 a flexibility of operation not always enjoyed by ultralights.\u00a0 As desired, the airplane can expand its performance capabilities and weight into the Experimental category, although that will require a license and medical certificate.<\/p>\n

The airplane is highly attractive, and has so many features that it\u2019s best to review these on the project\u2019s web site.\u00a0 Workmanship on the prototype is at a high level, and CNC-machined aluminum landing gear legs reflect an aesthetic that highlights the project.\u00a0 As numbers increase for flying products, Carpenter will offer budget alternatives, such as chrome-moly steel landing gear assemblies.<\/p>\n

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Despite all the features, it is an ultralight<\/p><\/div>\n

The airplane is meant to reach a $20,000 price point, with free plans available on line, much like those for Mike Sandlin\u2019s Basic Ultralight Gliders.\u00a0 Builders can fabricate as many parts as they are competent to make, but Brian will provide parts or complete kits as needed.\u00a0 He wants to demonstrate a different business model, keeping costs down and completions up.<\/p>\n

Carpenter\u2019s future plans for the craft show the breadth of his vision:<\/p>\n

    \n
  1. Gyro stabilized pitch control.<\/li>\n
  2. Gyro stabilized yaw control.<\/li>\n
  3. Regenerative motor capability.<\/li>\n
  4. In-flight adjustable-pitch propellers.<\/li>\n
  5. In-flight foldable propellers.<\/li>\n
  6. Solar cell wing covering.<\/li>\n
  7. Reverse thrust.<\/li>\n
  8. Vectored thrust short field takeoff.<\/li>\n
  9. Vectored thrust taxi maneuvering.<\/li>\n<\/ol>\n

    Interest in the new design is intense, with over 80,000 \u201chits\u201d on the web site in May and a three-part interview by EV World<\/em><\/a> on line drawing attention to the aircraft.<\/p>\n

    Readers can see the EMG-5 and hear Brian Carpenter\u2019s presentation at AirVenture 2012 in Oshkosh, Wisconsin.\u00a0 The airplane will be on display in Innovation Hangar A, quickly filling up with the latest in aeronautical thinking.<\/p>\n

     <\/p>\n