The 1957 Sorrell Triplane N6441C is a three-quarter scale replica of the WW1 Fokker triplane. Painted red, with silver rudder and white lettering, the single-seat Sorrell Triplane has a span of approximately 17 ft. 8 in., and is powered by a 65-hp Continental A65 flat-four.
The owner-constructor flew it from a private airstrip at Rochester (Washington State).
Satisfied with the lightweights, the Sorrells in 1967 constructed a sturdier negative-stagger single-place biplane powered with a converted 125 hp GPU by Lycoming. It had a streamlined fuselage profile with the windshield fairing right down to the spinner and no tapering of the side frames at the tail. Unusual was the method of mounting up – lift the rear portion of the skylight, climb up on top of the fuselage and slide down into the single seat.
Registered N3717 and named “Biggy Rat” by a younger Sorrell with an artistic bent, with the 125 hp and a very thin (10%) airfoil, “Biggy Rat” could cruise at 130 mph indicated – and could still operate with relative ease out of their 900 ft. cul-de-sac airport.
With a beefier structure and adequate power, John and Mark were able to indulge themselves in some aerobatics. “Biggy Rat” is very light on the controls – even touchy – and has done with ease all that has been asked of it in its 160+ hours of flying time.
The Sorrell SNS-4 N2026 fuselage is 4130 tube and is of constant width from nose to tail. The aft end squeezes down – from the top and bottom – and ends with a fuselage-wide elevator with an adjustable trim tab in the center. Two separate, fixed, horizontal stabilizer panels are attached to each side of the fuselage and are wire braced to the vertical fin. In early test flights the original fin proved too small for good directional control, so it was enlarged and supplemented by a small dorsal fin.
The equal span, constant chord wings are of all-wood construction. Each panel has three spars and no internal bracing – everything is kept square by a 1/8 in. plywood covering. The front spar is actually the leading edge, contoured to match the thin 10 percent airfoil. The top wing panels are attached to fittings on the upper fuselage longerons and the lower panels to the lower longerons with a doubled set of tie rods to take flying and landing loads.
The tie rod attach fittings are located inside the wing and inside the fuselage to minimize drag as much as possible. As the photos indicate, a wide “I” strut completes the wing truss geometry.
The top wings have narrow chord, full span ailerons and the lower panels full span flaps. Between the seats in the cabin is a Volkswagen parking brake lever – just where it is in a Beetle. With the lever all the way down the flaps and ailerons are in their normal, in-trail position; pull the lever up a notch and both the flap and aileron come down – the flap just twice as far as the aileron. Wiggle the stick and the ailerons work as usual in their lowered position. Another tug up on the lever results in more aileron droop and, again, twice as much flap, etc. until full travel is reached. Press the release button in the end of the lever and push it all the way down to take off all flap and aileron droop – or stop anywhere desired. The VW lever allows almost infinite-choice positioning – all push-rod actuated. It allows approach at 85 and touch down at 55 to 60 mph – its stall speed.
Mark Sorrell says that at the stall the wings obviously quit flying but the plane hangs on in a squirmy, squirrely fashion for a few more seconds – which he feels is the last gasp of the lift generated by the fuselage. When the little bird finally does quit, the remainder of the stall is docile and recovery is normal.
SNS-4 is powered b ya 125 hp GPU and cruises at 130 mph. The Lycoming fuel is from a main fuselage tank located between the panel and firewall. It has a capacity of 17 gallons which backed by an aux tank holding 11, makes 28 total.
The engine installation requires a shaft extension to get the metal prop as far out into undisturbed air as possible – and away from the cowling/windshield – for better efficiency.
The SNS-4 has fiberglas wheel pants that are constant in width. These wide pants allow the brakes to be enclosed. The brakes, are Montgomery Ward go-cart mechanicals.
SNS-4 is covered with ceconite and is white with a simple trim. The skylight – 1/8 in. plexiglas – is tinted green.
Completed on 12 July 1969, SNS-4 plans were never made available.
Sorrell SNS-4 – N2026 Engine: Lyc. 0-290-G, 125 hp Span: 21 ft 0 in Length: 17 ft 0 in Empty Weight: 818 Ib Max. Weight: 1328 Ib Fuel Cap: 28 gal. Cruise Speed: 130 mph Stall Speed: 55 – 60 ind. Seats: 2
In the early ’80s—at the height of the ultralight boom—one of Hobie’s sons, Tim Sorrell, designed a lighter, all-metal ultralight version of the Guppy and named it the SNS-8 Hiperlight. Siblings Mark, John and Lisa joined Tim in a company that marketed the all-metal, single-seat negative stagger biplane Hiperlight, which was quite different from other ultralights.
The kit can be licensed it in the Experimental/Amateur-Built or ultralight category LSA. The kit features a finished and powder-coated 4130 welded-tube forward fuselage and a welded 6061-T6 aluminum aft fuselage. The strut braced equal span wings and tail were built from premade welded aluminium alloy tube parts, and presewn slip-on covering made finishing the airplane easy. Originally powered by a single-cylinder, 28-hp two-stroke Rotax 277 with a Hegar belt reduction drive, later kits features a 28-hp MZ 201 two-stroke engine.
Full span flaperons are fitted to the lower wing. Centre mounted joy stick, rudder pedals, tailwheel steerable through rudder pedals.
The Sorrells were able to convince the FAA to grant an exemption to the ultralight speed limit (55 knots level at full power) as the Hiperlight easily flew at 65 knots. The Hiperlight has full-span sheet-metal ailerons providing a snappy roll rate, and controls are nicely balanced. As with many ultralight designs, the stall is without a break; it is simply a mush easily controllable in all three axes.
In 1984 the Sorrell Hyperlight sold for $8500 pre-fabricated or for $6500 as a kit, both with a 28 hp engine.
The SNS-8 can be landed gracefully in any pitch attitude from a nose-really-high, tailwheel-first one-pointer to a fly-it-on-level wheels landing.
SNS-8 Engine: Rotax 277 (268 cc) 28 hp Empty weight: 252 lbs Wing span: 22 ft Wing area: 140 sq.ft Height: 5 ft 3 in Length: 15 ft 6 in Fuel cap; 5 USG Construction: Aluminium, Dacron, Steel Max wt: 500 lb Stall: 27 mph Max speed: 63 mph Vne: 95 mph Climb rate: 600 fpm @ 38 mph Design limit: +6, -4g Glide ratio: 10-1 Wing loading: 3.57 lbs/sq.ft Power loading: 17.86 lbs/hp Seats: 1 Takeoff run 175 ft Landing roll 175 ft
SNS-8 EXP Engine: Rotax 447, 42 hp Speed max: 90 mph Cruise: 75 mph Range: 150 sm Stall: 30 mph ROC: 1200 fpm Take-off dist: 125 ft Landing dist: 150 ft Service ceiling: 12,000 ft Fuel cap: 5 USG Weight empty: 300 lb Gross: 550 lb Height: 5.25 ft Length: 15.6 ft Wing span: 22 ft Wing area: 140 sq.ft Seats: 1 Landing gear: tail wheel
Thunderbird Aviation Hiperlight SNS-8 Cruise: 60 mph Stall: 27 mph Range: 210 sm Rate of climb: 700 fpm Takeoff dist: 175 ft Landing dist: 175 ft Engine: MZ 201, 28 hp HP range: 28-45 Fuel capacity: 5 USG Empty weight: 247 lb Gross weight: 500 lb Length: 15.6 ft Wing span: 22 ft Wing area: 140 sq.ft Seats: 1 Cockpit width: 22 in Landing gear: tailwheel
Designed in 1975, the fuselage, tail group, engine/landing gear mount, interplane struts and flight control systems are all welded steel tube. Wing construction is all-wood with a stressed skin. Landing gear is the Wittman type. The engine cowling and wheel fairings are fiberglass. Then, the entire air¬frame is fabric covered, including the plywood-covered wings.
The prototype was SNS-6 N66S. The design won the EAA’s Outstanding New Design Award in 1973.
Advanced aerobatic maneuvers are possible in the Hiperbipe, such as vertical eight point rolls, inside/outside vertical eights, etc, but the Hiperbipe doesn’t sacrifice the comforts such as complete carpeting, full electrical system, lights and radio.
Basic kit includes fuselage sides, wings built, with wood and steel tubing and sheet steel. Price 1982: $4,950 basic kit, options to $19,000. Units delivered to June 1981: 87.
SNS-7
Engine: Lycoming IO-360, 180 hp Speed max: 170 mph Cruise: 160 mph Range: 502 sm Stall: 50 mph ROC: 1500 fpm Take-off dist: 400 ft Landing dist: 595 ft Service ceiling: 18,000 ft Fuel cap: 39 USG Weight empty: 1236 lb Gross: 1911 lb Height: 5.9 ft Length: 20.8 ft Wing span: 22.8 ft Wing area: 129 sq.ft Seats: 2 Landing gear: tail wheel
SNS-7 Engine: Lycoming O-360, 180 hp Wingspan: 6.95 m Length: 6.34 m Height: 1.78 m Empty weight: 521 kg MTOW: 861 kg Max speed: 330 kph Cruise: 250 kph ROC: 457 m/min
Designed by Hobie Sorrell of Tenino, Washington, in 1966, Fred Chandler of Ferguson, Missouri constructed this homebuilt project. Chandler says that the Guppy’s success is the result of a clean design combined with large wing area and light weight. He says that the design is very controllable in spite of its low engine power and small size. It is a rudder aircraft, and low speed makes it easy to handle.
SNS-1
The first two built, N2976G c/n 1 and N2180 c/n 2, were powered by an 18hp OMC Cushman 200 HO2 outboard boat engine. The Sorrell SNS-1 was the first Guppy (N2976G) and, as such, it is usually just referred to as an ‘SNS-2’.
Kit version uses 25-hp Citroen engine. Price 1982: $4,500 (includes engine and prop).