Letov ST-4 Aztek
The Letov ST-4 Aztek (English: Aztec) is a Czech microlight aircraft that was designed and produced by Letov Kbely of Prague - Letňany, in the 1990s. When it was available, the aircraft was supplied as a complete ready-to-fly aircraft, or as a kit for amateur construction.[1]
| ST-4 Aztek | |
|---|---|
![]()  | |
| Role | Microlight aircraft | 
| National origin | Czech Republic | 
| Manufacturer | Letov Kbely | 
| Status | Production completed | 
| Number built | 15 (1998) | 
In January 2014, the ST-4 was no longer listed as a product of the company.[2]
Design and development
    
The aircraft was designed to comply with the Fédération Aéronautique Internationale microlight category, including the category's maximum gross weight of 450 kg (992 lb). The ST-4 Aztek features a strut-braced high-wing, a two-seats-in-side-by-side configuration enclosed cockpit, fixed tricycle landing gear with wheel pants, a small tailskid and a single engine in tractor configuration.[1]
The aircraft is made from aluminum tubing with fairings made from fibreglass and its flying surfaces are covered in Dacron sailcloth. Its 10.40 m (34.1 ft) span wing mounts flaps and has a wing area of 15.21 m2 (163.7 sq ft). The wings are supported by V-struts with jury struts and the empennage is cable-braced. The acceptable power range is 45 to 50 hp (34 to 37 kW) and the standard engine used is the 50 hp (37 kW) Rotax 503 two-stroke powerplant. The engine is mounted high above the cockpit on the front end of the aluminum tube that acts as the tailboom.[1]
The ST-4 Aztek has a typical empty weight of 220 kg (490 lb) and a gross weight of 450 kg (990 lb), giving a useful load of 230 kg (510 lb). With full fuel of 57 litres (13 imp gal; 15 US gal) the payload for pilot, passenger and baggage is 189 kg (417 lb).[1]
The manufacturer estimated the construction time from the supplied kit as 80 hours.[1]
Operational history
    
By 1998 the company reported that 26 kits had been sold, and that 15 aircraft were completed and flying.[1]
Specifications (ST-4 Aztek)
    
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Data from AeroCrafter[1]
General characteristics
- Crew: one
 - Capacity: one passenger
 - Length: 5.91 m (19.40 ft)
 - Wingspan: 10.40 m (34 ft 1 in)
 - Wing area: 15.21 m2 (163.7 sq ft)
 - Empty weight: 220 kg (484 lb)
 - Gross weight: 450 kg (992 lb)
 - Fuel capacity: 15 U.S. gallons (57 L; 12 imp gal)
 - Powerplant: 1 × Rotax 503 twin cylinder, air-cooled, two stroke aircraft engine, 37 kW (50 hp)
 - Propellers: 4-bladed composite
 
Performance
- Maximum speed: 132 km/h (82 mph, 71 kn)
 - Cruise speed: 97 km/h (60 mph, 52 kn)
 - Stall speed: 50 km/h (31 mph, 27 kn) flaps down
 - Range: 341 km (212 mi, 184 nmi)
 - Service ceiling: 2,700 m (9,000 ft)
 - Rate of climb: 3.8 m/s (750 ft/min)
 - Wing loading: 29.5 kg/m2 (6.05 lb/sq ft)
 
References
    
- Purdy, Don: AeroCrafter - Homebuilt Aircraft Sourcebook, Fifth Edition, page 195. BAI Communications, 15 July 1998. ISBN 0-9636409-4-1
 - Letov Kbely (n.d.). "Products". Archived from the original on 11 January 2014. Retrieved 11 January 2014.
 
