{"id":8956,"date":"2014-05-31T10:59:59","date_gmt":"2014-05-31T17:59:59","guid":{"rendered":"http:\/\/cafe.foundation\/blog\/?p=8956"},"modified":"2014-05-31T11:40:35","modified_gmt":"2014-05-31T18:40:35","slug":"sunseeker-duo-goes-dual","status":"publish","type":"post","link":"http:\/\/cafe.foundation\/blog\/sunseeker-duo-goes-dual\/","title":{"rendered":"Sunseeker Duo Goes Dual"},"content":{"rendered":"

Irena Raymond became the first passenger of a solar-powered airplane<\/a> recently, even taking over control of the Sunseeker Duo she and husband Eric built over the last several years.\u00a0 Her thoughts provoke awe and envy.<\/span><\/p>\n

\"Irena<\/a>

Irena Raymond demonstrating light touch needed for control of he Sunseeker Duo<\/p><\/div>\n

\u201cFlying the Duo, skimming the white fluffy clouds from above and playing on the sky, I feel like a bird. No limitations, a pure freedom.\u00a0It\u2019s so quiet! Compared to a normal airplane, it\u2019s like night and day. You need a very good headset in every other powered airplane, but in this airplane you can speak normally even when the motor is running full power, no headset needed. It is unbelievable.\u201d<\/p>\n

Eric provides some hard data to complement Irena\u2019s understandably poetic words.\u00a0 \u201cI am expanding the flight envelope, so far up to 13,000 feet and 85 mph.\u00a0 My heaviest passenger\u2026 is 85 kilograms (187 pounds), and we were able to climb up to 12,500 feet.\u00a0 80 percent of the solar cells are hooked up.\u201d<\/p>\n

\"Italian<\/a>

Italian sunlight powers Duo in climb on its 1,500 solar cells – even with only 80-percent hooked up at this time. \u00a0Fully rigged, the airplane can stay aloft 12 hours at a time, ensuring long hops even at low cruising speeds<\/p><\/div>\n

Responding to a question from Dr. Brien Seeley, President of the CAFE Foundation, Eric explained the speed range he\u2019s explored so far.\u00a0 \u201cI am flying it under power at 40 mph indicated airspeed.\u00a0 It does well at 45 also.\u00a0 Gliding it varies from 30 mph up to 85 mph.\u201d<\/p>\n

\"Wiingover<\/a>

Wingover shows capabilities of large airplane in capable hands<\/p><\/div>\n

With its 23 meter (75 feet) span and 20 kilowatt (26.8 horsepower) motor, the Duo may seem a bit unreasonable.\u00a0 Its reported empty weight of 660 pounds is lower than that of a 65-horsepower Piper J-3<\/a>, though, and its low span loading helps it climb well on limited power.\u00a0 It\u2019s flying at Light Sport Aircraft weight on the equivalent of an open-class sailplane wing. \u00a0Its solar cells can charge the batteries after they’ve given 20 minutes of climb power, a good limit for an efficient sailplane, and one that can allow finding additional lift over a wide area.<\/p>\n

Eric\u2019s success at squeezing high performance out of low power causes him to question the claims of others who promise more performance with greater weight, shorter span, or some combination of ingredients that equal less than plausible aerodynamic or electrical achievements.\u00a0 In a phone call a few months back, he suggested your editor should perform similar tests of reasonableness on the claims any aircraft designer makes for his or her craft.\u00a0 In Eric\u2019s case, his unbroken stream of achievements shows his numbers are proof enough, and definitely part of the reality-based community.<\/p>\n

\"A<\/a>

A happy couple exploring the towering clouds<\/p><\/div>\n

Despite its formidable span, the wing can be readily folded to allow storage in a conventional hangar, taking up a \u201cfootprint no larger than a Cessna 172. The airplane can also be quickly disassembled and packed into a custom trailer.\u201d\u00a0 The latter was demonstrated when Eric and Irena hauled the airplane from her native Slovenia to its current airport home.<\/p>\n

The couple notes that the solar cells on the Duo are 50-percent more efficient than those used by Sunseeker II, which are efficient enough to allow that airplane to cruise in level flight on direct solar power.\u00a0 The Duo, they claim, can maintain a steady climb on sunlight alone, extending battery endurance.<\/p>\n

Its tricycle landing gear will make ground operations relatively easy, requiring no ground crew or wing-runners to assist in takeoffs.\u00a0 This practical level of operation will enable Eric and Irena to explore much of the world in sunny silence, a dream indeed. \u00a0 They will expand their cross-country experience soon, going on a 100-mile trip to a neighboring village, \u00a0undoubtedly dining on the equivalent of an American airport hamburger. \u00a0This could be the first zero-dollar airport lunch ever (food not included – but operating costs should allow ordering dessert).<\/p>\n