Maya Ultralight Aircraft – Pt 1, First Flight January 1985

Watch in HD (1280x720) for best results.

This ultralight aircraft was designed and built by myself (Graham.J.Percy) from 1979 to early 1985 with a good deal of encouragement from my friends. I am particularly grateful for all the help I received from my father Laurel.H.Percy and from Jim Ballinger, Greg Jessop, Brian Turner, Hans Van Meurs and Bob Walker. A full set of working drawings and construction manual were marketed during the later part of the 80s. Drawings are not currently available.

Construction is predominantly Sitka Spruce, Western Red Cedar, Finish Birch ply and aircraft grades of aluminium and steel. Total cost to build was about AUS$7500 including the excellent Konig SD-570 radial 2-stroke engine with geared propeller and electric start.

Moorooduc Airfield, Jan 1985

After ground running the engine at home initial flight testing was done at Moorooduc Airfield on the Mornington Peninsula in January 1985. This was done without the nose fairing or canopy. The canopy was left off to allow for more feel during early trials.

I started off by taxiing the aircraft at increasing speeds until I was able to lift the tail and maintain good directional control.

When I eventually left the ground and corrected the ascent the aircraft pitched forward and bounced on the ground. Pitching oscillations followed to which I immediately jammed my elbow against the inside of the cockpit to try to hold the stick steady but the oscillations continued so I cut the power and settled back down (technically "Pilot Induced Oscillations"), no damage. Difficult to see in the film, but look hard at 1:41-1:47.

Careful assessment (including great help from Merv Reed) revealed poor stick-free stability. I reduced elevator system inertia by reducing mass balance from 100% to about 50%, I increased elevator anti-balance tab gearing and increased tab size by about 150%. This increased stick feel or self-centering and reduced the destabilizing effect of system inertia...... back to the airfield!

Moorooduc Airfield, March 1985 (from 1:47)

Back for another try, this time high speed taxiing followed by steady level flight. Although the controls felt good I was now a little more cautious. After some more practice runs the first circuit went without a hitch during which I climbed to around 300ft, controls now seemed light and forgiving, landing was a breeze. First circuit from 3:25-5:25.

Nose fairing and canopy fitted with improved performance, from 5:30

Leongatha Airfield, September 1985 (from 6:08)

Hangared briefly at Leongatha Airfield in Gippsland. Beautiful clear and wide open spaces,
general circuits and experimentation with propeller and other settings. Measured steady climb at 500fpm. Best flying fun!

Aircraft Specification:-

General characteristics
Crew: one
Length: 17' 6" (5.33m)
Wingspan: 27' 10" (8.48m)
Height: 5' 5" (1.65m)
Wing area: 110sqft (10.2m2)
Empty weight: 248lb (112.5kg)
Gross weight: 480lb (218kg)
Fuel capacity: 3.9 U.S. Gallons (14.75L; 3.25imp gal)
Powerplant: 1 × Konig SD-570 4-cylinder 2-stroke motor, 28hp
Propellers: 3-bladed ground adjustable wooden propeller
Performance
Vne (never exceed): 100mph (87kn; 160km/h)
Level speed: 65mph (56.5kn; 105km/h)
Cruise speed: 60mph (52kn; 97km/h)
Stall speed: 37mph (32kn; 60km/h)
Range: 60mi (52nmi; 96km)
G limits: Manoeuvre +5.7/-2.25; Gust +6.44/-3.44
Rate of climb at sea level: 500ft/min (5.1m/s)

Filming by Laurel.H.Percy, all video content is Copyright Graham.J.Percy 2014

Although image quality is limited by the source material (Super 8mm Film) this video has been recorded in HD (1280x720) and gives best results when played back at that resolution.

The accompanying sound track was downloaded from the YouTube audio library and is in the public domain:- "Blue Skies", "neck Pillow", "Sophomore Makeout" and "Stay with You" by Silent Partner. Also, "No Pressha" by Jungle Punks.