By Jack Cox
(Photos by the Author)

THE GREAT NORTHWEST is something of a "living legend" area to sportplane enthusiasts. This is the land of Peter Bowers and his Flybaby, Molt Taylor and his Coot, Walt Redfern and his Fokker Tri-plane replica, to list a few designers whose names have become household terms - at least in EAA households! Jerry Bakeng and his "Duce" and "Double Duce" duo are the latest stars to flash across the firmament.

There are others, of course, but for some reason they have not become as well known outside their own locale. Hobie Sorrell is a name heard for years among homebuilders - a man who has had a thing for building scaled-down Fokker Tri-planes. A Continental powered Sorrell-built Fokker, later sold to the late Ron Conrad, is in the EAA Museum today and is one of the most popular exhibits. But how many of you would know Hobie on sight?

Go to a Northwestern fly-in, talk to homebuilt and antique owners about their aircraft and you will learn that the name Sorrell is linked with an amazing number of them - a Monocoupe wing by Sorrell, a set of Waco tapered wings for a Grand Champion . . . by Sorrell. A Warner-powered, Richthofen-red Tri-plane that flys and flys. . . by Sorrell! After a while, you begin to wonder about this guy Sorrell. You think something like, "He must be twins to put out this much work!" . . . and you would be on the right track toward the truth. Actually, there is a whole family of Sorrells - all involved in aircraft building and restoration work from their 900 ft. runway and home workshop in Rochester, Washington (population 350!).

If all goes well - and as planned - two "new" Sorrells, sons Mark and John, will be the next stars to skyrocket out of the great Northwest. And what a rocket they will be riding! When you get to Oshkosh next year, just look for the most unusual biplane on the field . . . and you will have found them. One look at the photos which accompany this article will give you a clue as to what to look for.

"Biggy Rat" et al

Hobie Sorrell has always been fascinated by lightweight, low powered aircraft and several years ago embarked with his sons on a program of progressive development of a very unique design. The photos do a better job than words, but the design can be described as a "flying" fuselage, negative stagger winged biplane which has evolved into a bullet-nosed speedster. The original two were single place, very light, and were powered with 18 hp Cushman golf cart engines. Surprisingly, they flew well, perhaps partly because they were properly designed and constructed and partly because they were flown by John and Mark Sorrell, both of whom are of average size and weight. They must have flown well because they were operated out of the - remember? - 900 ft. family strip which is ringed by a portion of that magnificent northwestern rain forest!

Satisfied with the lightweights, the Sorrells in 1967 constructed a sturdier negative-stagger ship powered with a converted 125 GPU by Lycoming. It had the same streamlined fuselage profile with the windshield fairing right down to the spinner and no tapering of the side frames at the tail - much like single bay of a huge wing. 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. Really sporting!

Named "Biggy Rat" by a younger Sorrell with an artistic bent (see photo), this bird was - and is - quite a performer. With the 125 horses churning away up front and a very thin (10%) airfoil, "Biggy Rat" could cruise at 130 mph indicated - and could still operate with relative ease out of that 900 ft. cul-de-sac airport.

With a beefier structure and adequate power, John and Mark were able to indulge themselves in a little aerobatics - a sport they were just taking to at the time. "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 to date.

The latest version of the Sorrell design is a "civilized" step away from "Biggy Rat". It ("it" has no name - how can you follow an act like "Biggy Rat"!!) has a wider fuselage, is a two-seater - side-by-side - with a really plush upholstery job, an auxiliary fuel tank behind the right seat and a different empennage . . . a "touring" model. "It" - well, it is called the SNS-4 on the nameplate - has one obvious fault, so let's get that out of the way to begin with and get on to the goodies. The cabin is small - o.k. for the lean and lithe young Sorrells for whom it was intended, but things would be a little tight for you swingers who delight in copious cups of Milwaukee's finest! The seating position is quite low resulting in poor visibility forward for shorties while the plane is in a 3 point attitude, but is adequate once the tail is up. This is, of course, true in the case of most taildraggers.

Now, let's take a close look at the SNS-4 - please refer to the photos frequently. Some learned and wise EAAer once said that you can't design a good homebuilt without putting a little Wittman into it - and the Sorrells acknowledge that they subscribe to this line of thought. A superficial examination of the SNS-4 indeed reveals a lot of Tailwind - Wittman tapered rod main gear and tail gear, windshield that flows back over the cabin to become a skylight, slab-sided, tubular fuselage and thin, plywood covered wings. But a more perceptive probing reveals that the design is really more in the spirit of Wittman than in physical fact - simplicity, ingenious detail work, and lightness a la Steve, but with a lot of Sorrell and Northwest originality to blend with it.

The fuselage is 4130 tube and is of constant width from nose to tail. This, naturally, adds some weight over a conventional, double-tapered fuselage, but has got to be strong! 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. It is a strong but light set up - the SNS-4 weighs just 818 pounds empty.

The most interesting feature of the wings, however, is the aileron/flap system. 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. This is the business end of a very ingenious flap/drooping aileron mechanism. 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.

This clever mechanism - all push-rod actuated - puts a lot of lift into the thin, symmetrical sectioned wing when it is needed - like landing at Sorrell International! It allows this rather hot looking little ship to approach at 85 and touch down at 55 to 60 mph - its stall speed.

The stall is another story. So far, we have neglected to speculate on the lifting capability of the airfoil-shaped fuselage. 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. As opposed to the sportin' blood of "Biggy Rat", the SNS-4 is easy to fly, according to Mark, and is much less sensitive.

SNS-4 is powered by the same 125 hp GPU as is "Biggy Rat" and despite added girth and weight, cruises at the same 130 mph. The Lycoming gets its liquid sustenance from a main fuselage tank located between the panel and flrewall. It has a capacity of 17 gallons which backed by the previously mentioned aux tank holding 11, makes 28 total - enough for pretty good cross country capability.

As can be seen in the photos, the engine is tightly cowled and has a very neat exhaust system. The 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. With its highly polished bullet spinner the sharp nose is . . . well, pretty sharp!

Both "Biggy Rat" and SNS-4 have fiberglas wheel pants that are shaped just like the fuselage - constant in width. These wide pants allow the brakes to be enclosed nicely - just another drag-saver. The brakes, incidentally, are Montgomery Ward go-cart mechanicals and work quite well - their selling price, as opposed to the aircraft variety, goes quite well on the wallet, also!

SNS-4 is covered with ceconite and is white with a simple attractive trim. A close inspection reveals top-notch workmanship. The skylight - 1/8 in. plexiglas - is tinted green and actually adds to the appearance of the plane. If you want a homebuilt with good performance, excellent finish, and a streamlined but unusual shape that will draw an admiring crowd wherever you land - then buy SNS-4 It's for sale so that the "rocket" we mentioned in the beginning can progress more rapidly.

As we said, if everything goes as planned, Mark and John will show up next year at Oshkosh with the ultimate negative-stagger Sorrell. It will have a larger cabin for comfort, a 12 percent airfoil and a 180 Lycoming. The bird will be fully aerobatic and Mark, who is already flying airshows in a Pitts, may show it off, given the opportunity.

A lot of you will like the looks of the Sorrell bipes, but unless you are seriously interested in SNS-4, please don't flood the family with mail - particularly, requesting plans. There aren't any. Let them concentrate on getting the 180 job off the ground so they can make it to Oshkosh - then, you can twist their arms in person!

Sorrell SNS-4 - N2026 Specifications
Empty Weight...818Ibs.
Date of Mfg....12-7-69
Max. Weight....1328 Ibs.
Engine.........Lyc. 0-290-G
Span...........21 M.
Length.........17 ft.
Fuel Cap.......28 gal.
Cruise Speed...130 mph
Stall Speed....55 - 60 ind.

Photo 1:
Mark Sorrell fires up his unusual negative stagger biplane, the SNS-4. Powered by a 125 Lycoming the sleek two-placer will cruise at 130 mph. Startling is the airfoil-shaped "lifting" fuselage which is of constant width from nose to tail. The plane has a unique mechanism that lowers the flaps on the lower wings and droops the full-span ailerons on the top wings simultaneously. This allows the otherwise hot ship to operate out of the family 900 ft. airstrip.

Photo 2:
(Photo courtesy Hobie Sorrell) The Number 1 (left) and Number 2 Sorrell negative stagger bipes. These two planes prove the theory that properly designed and constructed aircraft can be flown on very low horsepower engines.

Photo 3:
(Photo courtesy Hobie Sorrell) The man himself ‹ Hobie Sorrell. He is shown here with the first of the Sorrell negative stagger ultralight biplanes (with the cowling off). It has a span of 21 ft., length 15 ft., and weighs only 310 Ibs. empty. The engine is an 18 hp Cushman that pulls the little plane along at a cruise of 70 mph and tops out at 80. The landing speed is 38 mph. The 43 cu. in. Cushman burns just 1 1/2 gallons per hour and has been trouble-free. N2976G and a later version, N2180, fly well on these engines.

Photo 4 & Photo 5:
These two photos show the differences in the empennages of "Biggy Rat' (top), and the later SNS-4 (below). "Biggy Rat" has conventional control surfaces while the SNS-4's elevator is an extension of the fuselage. The out board horizontal stabilizer panels are fixed. The relatively small rudder has proven to be quite adequate. Notice the narrow chord, full span flaps (lower wings) and ailerons (top wings). The word "Experimental" on "Biggy Rat" is just where the FAA requires it ‹ at the entrance to the cockpit!

Photo 6:
John Sorrell demonstrates the method of entry into "Biggy Rat." Actually, climbing up over the side of the fuselage is much like getting into an open cockpit airplane ‹ with the advantage of being able to batten down the hatch cover and enjoy cabin comfort.

Photo 7:
SNS-4, left, and "Biggy Rat" pose side by side for easy comparison. The earlier "Biggy Rat" is single-place and has a longer, leaner look to it than the SNS-4, which is wider to allow for two-place seating. Nevertheless, both cruise at 130 mph on converted Lycoming 125 hp GPUs.

Photo 8:
"Biggy Rat" was the third Sorrell negative stagger biplane. Like all airplanes, this design is a bundle of compromises: it is a biplane so that the additional wing area ‹ plus that of the "lifting" fuselage ‹ will allow very short field take-off and landing capability and, at the same time, is cleaned up as much as possible to still provide good performance in the speed department. Notice the big rat painted on the nose ‹ a mean looking, red-eyed rat artistically done by a young member of the Sorrell family who came up with the name "Biggy Rat."

Photo 9:
Many features of the Sorrell design can be seen in this shot: the thin wings (10% airfoil) the constant width "lifting" fuselage; a wide stance Wittman landing gear with wheel pants shaped like the fuselage; and the very clean nose. Notice the neat exhaust system. The wing's tie rods attach to fittings well inside the fuselage and wings to minimize drag ‹ even the fuel filler cap is inside the fuselage. Look closely and you will see a small access door in the side glass just ahead of the cabin door.

Photo 10:
(Photo courtesy Hobie Sorrell) Still another Hobie Sorrell ultra-light is this interesting little biplane built and flown in 1958. It was powered by a 40 hp Mercury 4 cylinder outboard. Span was 20 ft., length 14 ft., and on empty weight of 300 Ibs. It flew well but according to Hobie, "had a voracious appetite for fuel."