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Spectra Aolus
It was a superb thermalling machine. In a strong, smooth core, you could push out past stall and flat-spin at 2000 fpm. Unique and unbelievable. With that reflexed tail, it gave you a very secure feeling that it would recover from going over the falls in violent thermals.
— Rick Masters (1)
In 1980, the Spectra Aircraft Corporation (of Concord, California) offered hang glider pilots a radical looking new wing: The Aolus. It had its roots in the popular curved leading edge Seagull 3.
I snapped the photo of the Spectra gliders on Plowshare Peak with my 110 flight camera on March 9, 1981. […] Carlos sold me the Zodiac prototype and he and Bill Dodson taught me to fly it at Guadelupe Dunes. In the photo, my Bennett knee-hanger harness is on the ground by the Zodiac with my Bell helmet. I can see the back of Carlos’ trusty Plymouth sedan behind it. Carlos stands with young Bob Dunn, the best cross-country pilot in the area, beside the prototype bowsprit Aolus (white) and the second model (blue). Dave Butz, a powered Easy Riser pilot and Aviation major, was our retrieve driver
— Rick Masters (2)
Plowshare is an inland site that was sometimes flown at night by moonlight. Roger Platt, the hang glider manufacturer from Poole in Dorset, England, who was by this time living near the Cal State Polytechnic at San Luis Obispo, saw “for sure” a UFO on a night flight trip at Plowshare. That experience inspired him to serious study of the phenomenon. At least one other hang glider pilot saw it too. (4) Could those sightings have influenced the design of the Northrop B-2 Spirit stealth bomber? (See American bomber on the Mitchell Wing page.) For Roger’s first flights in a hang glider, see Hang gliding 1974 part 4.
John Reisig started out assembling kits of the Seagull III and selling them. (That might sound trivial, but in this author’s experience, assembling hang gider kits was not as straight-forward as it should be. And, although I was an ‘agent’ in my area for a leading hang glider manufacture in Britain, I did not sell a single one!) Seagull eventually stopped supplying Reisig with kits. Trading as Suspended Animation, he then manufactured Seagull III clones, adding refinements that improved on the original. (3)
Aero engineering student Carlos Miralles designed a new sail for John Reisig’s curved leading edge frame. It incorporated battens, wide chord fixed tips, and anti-dive tip struts (the latter much as are still used in 2020). It went into production as the Zodiac (nearest wing in the main photo) which superficially resembled to the Seagull ‘Ten Meter.’
At weekends Bill Dodson drove from Cal Poly at San Luis Obispo, where both he and Carlos Miralles were students, to John Reisig’s shop in the San Francisco area. There, Dodson and Miralles created a series of prototype advanced hang gliders, culminating in the Aolus.
Because the thimbles on the nose wires eventually flattened out and the cable got longer, we had to make the cables short and do some hard wangs on the first flight to “set” the tangs before shipping a customer…
— Hang glider designer Bill Dodson
However, the Ultralight Products Comet and its clones, which finally incorporated a double surface sail that enclosed the cross-tubes — and did so without critical drawbacks — soon dominated the hang gliding scene. Bowsprit-rigged wings such as the Aolus had too many external cables that created drag when flying fast and they were unable to compete with the Comet.
We tried pushing the Aolus planform to its performance limits by building versions with a large amount of double surface and an enclosed crossbar. While prototypes flew very well at cool beach sites, the design turned out to have unusually high sensitivity to temperature due to its low sweep. A glider tuned to fly at the cool beach ended up being unmanageable at hot inland sites due to differences in sail tension as the tubes expanded in the heat.
— Bill Dodson
The British Flexiform Sealander closely resembled the Aolus. The first reference to it that this author has found is in the February 1981 edition of the British hang gliding magazine. See under External links later on this page for a walk-around of a preserved Sealander in 2020.
Another British design with a similar tail, but with flexible curved tips as used on many flex-wing hang gliders in the 21st century (2020) was the Hiway Alien of 1982. However, the Alien — unlike the Aolus and the Sealander — used cross-tubes (inside the double surface sail) rather than a bowsprit. It never reached production status.
Together with the Gannet, the Sigma, and the Sealander, the Aolus was the last of the bowsprit-rigged high performance hang gliders. However, the bowsprit-rigged general arrangement lived on in a line of gliders made by Bautek of Germany. Light in weight and with nimble handling and excellent sink rates, they continued to be made until Bautek closed in early 2020. The bowsprit configuration additionally confers the safety advantage that, in the event of a ‘nose-in’, the pilot cannot be struck on the back of he head by the nose of the glider, which is a danger of some other types of hang glider.
Carlos, the designer for John Risieg’s Spectra Aircraft, was an Aviation major at Cal Poly, San Luis Obispo. Bob was an Electrical Engineering major and I was a Mechanical Engineering major. We were cutting classes that Monday because of the great weather forecast. The Zodiac was similar to the Seagull 10-meter that George Worthington had established world records in Owens Valley on flights from Cerro Gordo. But in the short period between the single surface ships and the full double-surface gliders to come, the half-double surface Aolus was a racehorse. Bob and Carlos would zip all around me while I wallowed happily in the superb lift.
— Rick Masters (2)
One of the Aolus designers applied for a job with a major airplane manufacturer and the aerodynamicist interviewer asked mostly questions about his hang glider design expertise and knowledge. That was the experience they were looking for in designing a secret flying wing.(3) I assume some of his subsequent design projects might still be classified, but it is safe to say here that one was a supersonic stealth fighter. (Two prototypes flew, but it was eventually rejected by the U.S. Air Force.) Another holds world records (standing in 2020) for combat mission length and duration. See also American bomber in Mitchell Wing.
Related
Flex-wings with tails related topics menu
Gannet: Hang gliding early 1980s part 1
Hiway Alien: Hiway of Sussex, England, and Abergavenny, Wales related topics menu
Lightnings, Comet clones and pod people in Hang gliding early 1980s part 1
Seagull III and Seagull Ten Meter: Seagull Aircraft of Santa Monica, California related topics menu
Sigma: South downs in Hang gliding early 1980s part 1
Ultralight Products Comet: American revolution in Hang gliding 1978 and 1979 part 3
External links
Aoli, Comet Clones & Pod People: Rick Masters’ page about flying and competing in the Owens Valley, California
Preserved Flexiform Sealander walk-around in 2020 on the British Hangies UK Facebook group
References
1. Rick Masters: Dangerous Thoughts on US Hawks forum (scroll to subtitle The Aolus Boogie)
2. Rick Masters’ comment in Hang gliding late 1970s and early 1980s on Brave Guys and Beautiful Dolls
3. Post by wingsmith (Bill Dodson) on Hanggliding.org forum, Sun Dec 11, 2011 2:36 am
4. Roly Lewis-Evans e-mail dialog with the author in July 2021
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