Glasair III

The Glasair was the first kit aircraft that used moulded surfaces rather than the Rutan method of construction. The original Glasair 1 required a very long time to construct, but the newer kits are comparable with other complex kit aircraft. Fast build options are available. The original company, Stoddard Hamilton, (named after the late designer) went into liquidation due to reasons outside the Glasair range. Fortunately the company was purchased by aircraft enthusiast Thomas W. Wathen and is now going from strength to strength.

The Glasair is the ideal long distance fast personal aircraft. These aircraft are not only extremely strong, but fly better than almost any experimental. They are renowned for their handling characteristics. In addition, the resins used very rarely cause allergy problems for builders. The Glasair III is renowned for its performance.

In its evolution from the earliest Glasair models, the III has grown 30" in overall fuselage length, both forward and aft of the cockpit. The increased length has given the III markedly improved longitudinal and directional stability, making it an impressive platform for serious cross-country and IFR flying. (The Super II line incorporates these changes as well.)

Since the Glasair III cruises at speeds up to 313 mph, the factory-moulded fuselage halves of the III feature incorporate two additional layers of fibreglass in the outer skin laminates behind the cockpit to significantly increase the torsional rigidity of the aft fuselage. Two composite ribs located inside the vertical fin are bonded to the horizontal stabilizer to increase stiffness in this area as well.

The belly section of the III fuselage is stronger and stiffer than that of the Super II, and it incorporates a strong multiple-screw and nutplate attachment in the centre section for ease of removal. The forward belly panel comes with pre-moulded cooling air exit ramps designed to optimize engine cooling and exhaust installation for the III’s six-cylinder engine.

The well for the retractable nose wheel is supplied as a pre-moulded composite part with high-density foam core inserts moulded in for attachment of both the nose wheel doors and the rudder pedals on the inside of the cockpit.

Fire-retardant, closed cell polyurethane foam core is used in all areas of the III fuselage, including the firewall.

The Glasair III’s wing span and area are the same as those of the Super II -- 23', 3" and 81.3 sq. ft., respectively. However, the lower aft surface of the LS(1)-0413 airfoil has been modified in the aileron and flap area on the III to reduce induced drag, profile drag and trim drag. This change, coupled with the upswept Hoerner tips, provides light aileron forces even at higher speeds.

To provide the additional strength required for the 335 mph redline speed of the III, extra laminates are moulded into the wing skins and spars. In addition, the main spar attach fittings and the wing attach support brackets on the fuselage are larger than their counterparts on the Super II, and the composite airframe structure around the wing attach points has received extra reinforcement.

The Glasair III wing features pre-moulded main landing gear support boxes. These rigid, structural boxes eliminate the majority of the laminating and jigging work on the main landing gear installation and simplify the job considerably.

Control Surfaces
The Glasair III uses the same horizontal stabilizer airfoil section as the Super II. However, graphite fibers have been incorporated into the skin laminates of the III stabilizer and the span has been shortened compared to the Super II to obtain the higher degree of stiffness and torsional rigidity prescribed by our in-depth vibration testing and computer flutter analysis.

The III also features larger-diameter aluminium push-pull tubes for the aileron and elevator control systems than earlier Glasair models, providing increased column load capacity. Increased mechanical advantage is provided in the flap control system, which has been designed to reduce the effort required for flap actuation while maintaining a simple manual linkage. Electrically actuated flaps, both standard and slotted, are available as options.

Landing Gear
Durable oleo-pneumatic landing gear struts are used for all three wheels on the Glasair III. These are top quality, rugged and designed with low-maintenance features throughout. Internal fluid metering has been customized for the Glasair’s weight to give smooth taxiing over rough ground, as well as proper damping for hard landings. The internal parts are designed so that specialized wrenches are not required for disassembly, and service can, if necessary, be accomplished by a novice with the detailed service instructions New Glasair LLC - New GlaStar LLC provides.

The landing gear is retracted by an electro-hydraulic pump driving actuating cylinders. The complete retraction cycle takes about ten seconds. The gear is controlled by a switch on the instrument panel and monitored with a panel-mounted hydraulic pressure gauge and three gear position lights. The lights indicate gear down and locked (green), gear in transit (red), and gear up and locked (lights out). Additionally, a warning horn is activated if the flaps are lowered prior to gear extension.

The III also features a gear up-lock system, which is essential for any high-performance retractable-gear airplane, especially one that may be subjected to high-G, aerobatic manoeuvring. The up-locks release automatically when the hydraulic actuators begin their cycle.

Another standard system on the III is a cockpit-operated, manual system for emergency gear extension -- obviously an important safety feature. The system, which utilizes a hand pump and special single-direction actuators, is completely separate from the main hydraulic system, providing true redundancy in the event of a malfunction.

The massive oleo nose gear installation mates to the engine mount in a simple, bolt-on operation. The strut features a heavy-duty machined shimmy damper collar, which is important for high speed taxiing. The nose wheel of the III -- like all tricycle-geared Glasairs -- is free-castoring. Steering on the ground is accomplished with differential braking at very slow speeds and using the remarkably effective rudder at higher taxi and take-off speeds.

The landing gear also features a powerful braking system including master cylinders, reservoir, aluminium tubing brake lines, fittings and heavy-duty brakes. These brakes use 3/8"-thick discs, which provide better heat dissipation and permit higher piston forces on the pads than standard, 5.00 x 5 brakes.

The Glasair III cowling has been optimized to provide outstanding engine cooling with minimal aerodynamic drag. The protruding exhaust tunnel common on other Glasair models has been eliminated on the III in favor of twin exhaust stacks that protrude only slightly beyond the cowling. This change greatly reduces drag by allowing for a sleek, uninterrupted belly contour from spinner tip to tail.

The III cowling is manufactured with extra stiffness because of the airplane’s high-speed capability. The cowling halves are made exclusively with special fire-retardant resin and foam core materials.

The oil access door is factory-moulded and ready to install into a moulded inset in the upper cowling. A flush-fit landing light lens sized to fit a moulded recess in the lower cowling is also a standard kit feature.

The Glasair III uses a certified Lycoming aircraft engine. With such exciting cross-country capabilities, having a proven, reliable engine is a must.

The Glasair III is designed to use the most readily available 300 hp Lycoming engine, the IO-540-K series. The engine installed in our prototype III is a smooth-operating -K1H5. This engine has the fuel injector mounted on a straight air inlet housing on the aft side of the engine oil sump. It is equipped with a Bendix RSA-10ED1 fuel injector, a diaphragm-type fuel pump and drive, and two impulse coupling magnetos.

The IO-540-K1H5 engine can be purchased new direct from New Glasair LLC - New GlaStar LLC at an attractive, original equipment manufacturer’s (OEM) price, but this engine is unlikely to be found on the used or overhauled market, since it is not used on any production aircraft. Several 300 hp IO-540 models that do show up frequently for sale can be used in the III, however.

The factor that determines which models can easily be used is the engine induction system. Induction air in the III is routed from a NACA duct on the left side of the cowling through a full-time air filter connected to the injector body by a moulded flex coupling. The injector is mounted sideways in the cowling on a 90° steel elbow (supplied in the standard kit) that fits onto the engine’s air inlet housing. In order to obtain the proper firewall and engine mount clearance for this induction system, a straight (rather than angled) air inlet housing must be used on the rear of the oil sump.

Because they were used in the Piper Cherokee Six, the 300 hp IO-540-K1A5 and -K1A5D (with impulse coupling magnetos) are widely available as used engines and would be good choices for the Glasair III. These engines used aft-mounted, 38-1/2° offset air inlet housings instead of the required straight housing, but exchanging housings is a simple and relatively inexpensive operation.

Note: The common fuel pump on the Cherokees was the smaller but very expensive Lear-Romec style.

The 300 hp IO-540-K1E5, used on the Bellanca Viking, is also readily available used. It comes with the straight air inlet housing, Lear-Romec fuel pump, and Bendix RS-type fuel injector. This style of Bendix injector, unfortunately, is not optimal for use in the Glasair III. If you want to use this engine, we recommend exchanging the RS injector for an RSA-10ED1 injector.

Note: Many other models of the Lycoming IO-540 can be modified for use in the Glasair III. If you find a great deal on an engine not discussed above, call our Builder Support Department for advice.

Both 80"-diameter Hartzell and 79"-diameter McCauley Blackmack two-bladed, compact-hub constant-speed propellers can be used on the Glasair III. After extensive testing, two-bladed props were selected over three-bladed models due to their efficiency, lighter weight and lower cost. The landing gear legs are sized to give a healthy 10" of ground clearance with either of these props.

The prop is not included in the kit, but a complete spinner installation is standard. The composite spinner is manufactured to perfectly match the loft lines of the Glasair cowling. Hartzell and McCauley propellers are available, factory-new, at OEM prices direct from New Glasair LLC - New GlaStar LLC.

wing span
wing area
empty weight
useful load
gross weight
fuel capacity
300 h.p.
21.3 ft
7.5 ft
23.3 ft
81.3 sq ft

2,400 lbs
65 gal    8 gal header Tank   11 gal  Wing Tip Extensions


takeoff distance, ground roll
rate of climb
max speed
cruise speed
landing distance, ground roll
service ceiling
2990 ft/min
260 knots
272 knots (turbo)
30,000+ ft. Turbocharged

limiting and recommended speeds

design manoeuvring speed (Va)
never exceed speed (Vne)
stall, power off (Vsl)
landing approach speed
174 knots
291 knots
69 knots

All specifications are based on manufacturer's calculations