EAAers Lead A New Class Of Personal Aircraft
'Alberto' A Hybrid Between Blimp And Hot-Air Balloon
December 14, 2006 — A new kind of aircraft-a personal, semi-rigid thermal airship-flew for the first time on October 27 in Amherst, Massachusetts. Called the Alberto, it's being developed by a company called Skyacht Aircraft, Inc., led by two EAAers, Dan Nachbar (EAA 676916) and Mike Kuehlmuss (EAA 405232).
Alberto, whose name pays homage to Brazilian aviation pioneer, Alberto Santos-Dumont, is 102 feet long with a 70-foot diameter and uses hot air rather than helium for lift. Its innovative foldable frame (much like an giant umbrella) creates structural support of its hot-air envelope, and it has a fly-by-wire vectored thrust steering system. Alberto is a hybrid; a hot-air balloon with aluminum ribs that looks more like a blimp, but with a tail propeller that gives it directional control.
The idea that resulted in Airship Alberto came as a result of a cross-country flight Nachbar made several years ago in a Cessna 172. "The view is great," he recalled thinking while flying over Tennessee, "but the noise is awful. I need to find a way to fly without so much noise."
He began investigating blimps and hot-air balloons, but soon realized each had limiting factors that made them impractical for what he sought: Quiet, safe, affordable flight with enhanced maneuverability.
Helium airships have full control in only two dimensions. They have adequate forward motion and steering but suffer from limited up/down control. They also require large ground crews. Hot-air blimps have adequate up/down control using the burner, but they lack adequate steering control, especially at the low airspeeds required for approach to a mooring mast.
About five years ago, Nachbar's friend John Fabel hit on the idea of using giant aluminum tent poles that run from nose to tail to form ribs on a giant fabric envelope, sort of like two large umbrellas. They received a patent for the unique structural design about two years ago.
The idea for the tail-mounted propeller came from the helium-filled Zeppelin NT. The combination of hot-air lift on a framed envelope and a tail-mounted, swiveling propeller creates for the first time, so far as Nachbar can tell, an airship with full control in all three dimensions.
"I've asked everyone I can find in the past five years and this appears to be absolutely unique," he said. "It is capable of slow, low-level flying where one can literally pick the top leaf off of a tree as well as turn-on-a-dime steering that balloons and conventional blimps simply cannot match."
However, that uniqueness presented a problem: Alberto was certificated as an experimental lighter than air (LTA) airship (N111SY), so pilot requirements call for an airship rating, but the requirements to obtain that rating don't have much to do with how the Alberto operates.
"The Practical Test Standards and all the training for an airship rating, it's all about managing pressurized helium-based aircraft," Nachbar said. "Alberto is neither pressurized, nor does it use helium, so we don't fit into the FAA's regulatory box."
As a result, Skyacht, with help from EAA, requested a grant of exemption this week from Federal Aviation Regulations to allow a person with a private pilot certificate, SEL, to act as pilot in command with a passenger so long as the PIC has a balloon rating where both the flight experience requirement and the flight test requirement were fulfilled using a balloon with an airborne heater; and has logged five hours in Alberto.
"I am very optimistic because we really do have something new and different," Nachbar said. "We're outside the mold. But I can tell you from flying it, if flies very much like a hot-air balloon. The speeds are much lower. The big deal with helium airships is, because you cannot control the buoyancy, you spend a lot of time pointing the nose up and down to control the up/down, whereas the up/down in ours is a matter of firing the burner vs. not firing. It's a very different beast."
Next for Alberto, which completed the 10 hours of phase 1 test flights in November, is to switch out the gas-powered engine for a quieter electric one and develop a quieter burner. After that, they'll turn the R&D crank again. "This aircraft is really a proof of concept prototype," Nachbar said. "It doesn't go very fast, doesn't go very far. The next ship will be longer and skinnier, we'll put a bigger engine on it, get the airspeed up."
A third technical thrust is to work on developing a mooring mast in order to make flying Alberto more practical. To learn more, visit www.personalblimp.com.
Daniel Nachbar started his engineering career in 1982 as a computer science researcher at Bell Labs. He continued his work in computer research and development at several established and start-up telecommunications companies until 2001, when he switched his research focus to aircraft design. Nachbar presented the forum, "Building A Next Generation Personal Hot Air Blimp," at EAA AirVenture Oshkosh 2006.
Michael Kuehlmuss (Mechanical Design and Fabrication) After studying Aeronautical Engineering at FH Munich, Germany, Mike moved to the United States in 1990 and became an A&P/AI mechanic as well as a commercial pilot. Overall, he has built, maintained, and flown both type certified and experimental aircraft for over 12 years. Mike is the owner and operator of Flightworks of Northampton, Inc.