Ninety percent of the technology for Dale Kraner's electric Lazair came from the model airplane industry.
PHOTO BY MARIANO ROSALES
Electric flight was a longtime dream for Dale Kramer, designer of the Lazair ultralight.
Now his dream has come true. His current amphibious configuration found the flying success that evaded him in three previous electrification attempts.
Kramer remembers few details of the first attempt, but the second sought to draw from electric flying model technology.
“They were just coming out with the high voltage controllers for model airplane engines, and they just weren’t ready,” Kramer said. “After I blew a couple I decided they weren’t reliable enough.
“That was going to be a four-engine Lazair. The smaller engines at the time were putting out 25 pounds of thrust each, and that version would not have flown on floats.”
Next came an attempt to use electric technology from the automotive world. That path, too, was rife with challenges.
“To make the car motors light enough would have been too much of a design change. So I bought the controller, but I never did use it,” he said, adding, “Ultimately it was more money than I wanted to spend.”
Attempt number four is flying and on display here at EAA AirVenture Oshkosh 2011.
Believing that technology had advanced significantly since his prior effort, Kramer returned to the model industry. He estimates 90 percent of the electric platform came directly from off-the-shelf components, though much remained to be done.
“I built the whole power system, everything that wasn’t off the shelf, myself,” Kramer said. “I spent a lot of time on the throttle quadrant because I wanted my throttle signal to be reliable. It sends a very uniquely shaped, pulse-modulated signal, but it still uses mostly off-the-shelf components.
“Battery integration was another tedious area, making up all the circuit boards to connect the batteries in series and in parallel.
“It was tedious, but not rocket science.”
The present configuration was not without early challenges.
“This is the second set of motors I’ve had for the airplane in the last six months,” Kramer said. “The first set was directly from the model airplane industry, and they just didn’t have a good enough design to keep them from overheating.
“Model motors are typically made for 6-10 minute flight durations, and not full power all the time. So they work in that industry, but in this application you need something that can move the heat into the slipstream.”
The craft’s current powerplants are an “inrunner” design from Joby Motors. According to Kramer the inrunner design is far superior at transferring heat out of the motor than the earlier configuration.
On a full charge and configured as a landplane, the Lazair delivers 75 minutes of flight from its 100 pounds of lithium-polymer batteries. As an amphibious floatplane, extra drag and weight reduces flight times to around 45 minutes.
Kramer’s system is capable of bringing the batteries to a full charge in 75 minutes. But doing that requires six dedicated household 110V electrical circuits. Charging from a single 110V circuit requires eight to nine hours.
A set of batteries should last about 300 hours, and Kramer sees that as a positive. “My expectation is that when I replace these batteries in the next couple of years the new ones will be two to three times the endurance at the same weight,” he said. “And that is conservative. I’m hoping it will be much higher.
“There is a lot of stuff on the horizon.”
Most Lazairs were manufactured with a pair of 9.5-hp gas engines, so Kramer’s 32-year-old design was a good candidate for the roughly 13-hp electric motors now affixed to its wing. In fact, the airframe he chose for this project came out of the factory 28 years ago and spent time as a demonstrator.
Ultimately it was sold, but 25 years later a listing on eBay prompted him to buy it back.
Kramer hopes to someday experience an all-electric cross-country flying adventure, though he sees the lack of a national rapid charging infrastructure as a challenge.
In the meantime he plans to fly it off the lake in front of his Hammondsport, New York, home and invite some of his close friends to come and fly it.
“I know there are people that will just be blown away by it.”
DATES: 2014: July 28-Aug. 3;
2015: July 27-Aug. 2