Mountain Goat STOL


The MOUNTAIN GOAT STOL is the result of seven years of development, addressing the particular needs of Alaska bush pilots. Two years were spent researching the requirements and disposition of bush pilots, including perceived shortcomings of the existing bush plane fleet; useful load requirements; undesirable flight qualities of the existing bush plane fleet; undesirable structural qualities of the existing bush plane fleet; determination of the real world performance of the existing bush plane fleet; what happens in typical crashes; FAA regulations related to certification processes; design criteria needing to exceed the requirements of FAA regulations; and available, state of the art technologies capable of benefiting design goals predicated by the research.

Some things we didn't learn until after we built our first prototype. We found for instance that in some cases, field repair capability is considered preferable to advantages measured purely in terms of performance. Over a period of several more years, each issue raised by the bush pilot community was addressed. A composite wing was eliminated over concerns of "in field" serviceability. A new technology for an all metal wing was developed which provides the cost benefits of a metal wing while achieving the aerodynamic benefits of a composite wing. Engine power output was increased to 180 horsepower factory specs, with additional performance derived from exhaust and propeller refinements. We developed an exceedingly quiet, high-performance exhaust. Additional aerodynamic modifications were made to achieve better performance. One of the greater challenges was to design an empennage providing the performance required for FAA certification standards, while providing equally outstanding performance at 180 mph IAS and above.

The MOUNTAIN GOAT STOL™ uses as standard equipment, a McCauley 76-inch diameter, 66-inch pitch, fixed pitch prop. We regularly operate out of short, rough strips at any altitude, taking off and landing in the same distance as a good, lightly loaded Super Cub™ with an 82 inch prop with 40 inches of pitch — a rig which substantially benefits the Super Cub™ to achieve speed and climb.

As soon as we are off the ground, we are climbing at over 1,000 ft per minute — at a faster speed than the Super Cub™ will fly at full throttle and level. If the Super Cub™ is in stable, maximum rate of climb, full power, with the 82 / 40 prop, and the MOUNTAIN GOAT STOL™ has the same load and full throttle, the Super Cub™ will be climbing at about 1,200 ft/min, at about 63 mph at 3,000 ft. The MOUNTAIN GOAT STOL™ will be climbing at 2,200 ft/min, at 110 mph.

The MOUNTAIN GOAT STOL™ can take off in short distances because the wing has more than twice the lift of a Super Cub™, and less than half the drag. The wing uses a state of the art airfoil developed from aerospace research by Bill Montagne, implemented in a flush riveted wing, flaps, and flaperons. The accurate structure of this wing, and its state of the art mechanical and aerodynamic technology, distinguish MOUNTAIN GOAT STOL™ performance above what are really antiquated designs, far behind the curve of modern developments. We don’t use an 82 /40 prop, because we can achieve substantially superior performance without the diameter and pitch, and without the inherent landing clearance risks.

wing span
wing area
empty weight
useful load
gross weight
fuel capacity
Lycoming IO 360 B2E, 180 HP, 2000 hr TBO
McCauley fixed pitch 76-66
24.3 ft
6.75 ft
35.5 ft
188 sq ft
1250 lbs 4130 Chrome Moly alloy airframe; 1170 lbs Titanium airframe
1250 lbs 4130 Chrome Moly alloy airframe; 1330 lbs Titanium airframe
2500 lbs
65 US gallons
1,400 statute miles

performance (Mountain Goat STOL  with 26ins dia × 10.5 × 6 Goodyear Tundra tyres)

takeoff distance, ground roll
rate of climb
max speed
cruise speed
landing distance, ground roll
service ceiling
300 ft
1,200 fpm
159 mph
275 ft

limiting and recommended speeds

design manoeuvring speed (Va)
never exceed speed (Vne)
stall, power off (Vsl)
landing approach speed
120 mph
50 mph

All specifications are based on manufacturer's calculations