Sport Pilot Reprint: STOL CH 701

There's something to be said for knowing when to leave well enough alone. After all, when something works just the way it is, why mess with it?
Of course, there are those in the aviation world to whom the status quo is anathema. Traditionally, aviation writers have been among these voices. We like to see new and improved products, frankly, because it helps generate copy and sell magazines. It's usually easier to write an article about a brand-new product than one that's been around for a decade.

It's not called the STOL for nothing. Takeoff and slow-speed performance is amazing.

We aviation hacks should be forgiven for rushing to look deeply into every shiny new bauble on the block. The single most effective word you can print on the label of a product is "NEW." Consumers assume that because it's new, it must be better. Sometimes it is, sometimes it isn't.
But, Madison Avenue aside, when it comes right down to it, if you want to read a story that's straight from the heart of a writer, read about an airplane we consider a classic, an aircraft which appeals to our sense of timelessness, proportion, and function. To me, the Zenair CH 701 is one of these aircraft.

`STOL´ is no exaggeration. Landing distance, it seems, should be measured in inches instead of feet!

For those of you not familiar with it, the 701 is one of the aircraft created by prolific designer Chris Heintz. Heintz is a former aerospace engineer who worked on the Concorde and helped design some of the most popular light planes in Europe, including several for Robin in France.
Heintz moved to Canada in 1972 and went to work for de Havilland. In his heart of hearts, however, he dreamed of selling aircraft of his own design, so that's just what he did. In 1974 Heintz showed up at the very first Sun 'n Fun with his all-metal Zenith CH 200, a low-wing sport plane years ahead of its time.
Over the years Heintz has designed nearly a dozen more aircraft, some of which are now out of production and others which have not yet seen the light at the end of a wind tunnel. Of all those aircraft, the most visible and successful has been the diminutive CH 701, a true sport flying classic.

For ten years the STOL CH 701 has been a favorite of homebuilders around the globe. Affordable, easy to fly and to build, the STOL 701 is a tough act to top.

The 701 is an unusual looking airplane, one few would call a natural beauty. Still, even if its lines are somewhat exaggerated, it possesses the uncompromising air of the seriously practical machine it is.
The most striking features of the 701 are its full-span leading edge slats. Though reminiscent of those on the Helio Courier, the slats on the 701 are different. The units on the Helio are spring-loaded, to be opened when the air pressure decreases below a certain level. The idea is to add lift at slow speeds, where drag isn't really a big factor, and cut drag at high speed by having the slats retract. Unlike the Courier, the 701, outfitted with a low-displacement two-stroke engine, isn't fast enough to benefit from variable slats, so its slats are fixed, like separate little wines out in front of the main airfoil. Heintz contends that fixed slats, instead of the more complicated spring-loaded ones, reduce building complexity and reduce weight as well as keep down cost and improve reliability. Besides, the performance gains of spring loaded slats, if any, would probably be minimal.


A close-up of the leading edge slats	Unusual is the only word for the 701. The horizontal stab features a convex airfoil and the rudder is an all flying unit

As you'd expect, these mini airfoils alter the center of lift of the airplane, bringing, it forward several inches, even out in front of the cabin.
The rest of the wing is fairly unusual, too. For starters, it's only 27 feet in span, though it makes up for it in chord with an overall wino, area of 122 sq. ft. Gracing the trailing edge of the 701 wings are full-span flaperons. The shorter span helps in storage of the aircraft and makes it less susceptible to wind gusts. Moreover, it's stronger because it has to support less span.
The other strange looking (once you actually notice it) component is the tail. Heintz has always liked all flying tails such as those found on Piper's Cherokees, among other aircraft. Now the term "flying tail" usually refers to stabilators, combination elevator/stabilizers which pivot on a hinge, thereby providing good aerodynamic balance and easy trimmability. Heintz has taken the concept one step further, however, by outfitting the 701 with a flying rudder as well. If you look closely, you'll see that the vertical tail surface of the airplane is built so that the top part of the rudder extends well past the natural pivot point. The effect of the whole arrangement is excellent authority from surfaces smaller than you'd expect could do the job. Heintz justifies the unusual design by pointing out that the flying surfaces help the 701 maintain control response at very low speeds and with substantial crosswinds.


A good view of the bomb-proof gear. The nose gear is mounted to a bungee suspension chord which is attached directly to the firewall.	The right stuff is the light stuff. Here Nicholas Heintz shows off the featherlight door of the 701

Constructed mostly of lightweight aluminum alloy, the CH 701 is an example of a design on which the pounds are made to count. If the question is "Where's the beef?" the answer is, "In all the right places."
The first of those two "right places" is the wing, spar (one of my favorite components to be overbuilt). Featuring built-up "I" beam construction, the spar is completely pre-assembled in the shop. Because of this, the component can make use of heavy-duty conventional aircraft rivets. Believe me, it's bombproof.
The envelope, please. The next component to receive the lifetime achievement award is the landing, gear. The main gear is a single piece of 3/4 by 4inch stock bent to shape and fastened to the fuselage substructure with heavy duty u-bolts. You're not ever going to break this gear. Attached to this under-carriage are two 1/4-in aluminum wheel yokes fitted with 16-inch wheels with hydraulic brakes. The nose gear is nearly as strong, and more cleverly executed than the mains. Unlike the nose gear on most production aircraft, the unit on the 701 is essentially a single 2-in, .058-in wall chrome moly tube attached to a wheel yoke similar to that on the mains. Suspension is achieved (this is the brilliant part) though the use of a bungee chord attached both to the main nose gear leg, and the firewall. The nose gear is not only cheap to build and easy and cheap to maintain, but it will take a heck of a lot of punishment and just keep right on bouncing.


With bold angles and jutting lines, the 701 has uncompromising styling. Beefy: With this gear you can get away with a few bounces.	The panel is all business, though there is room for goodies if the builder so desires. Note the Y-handled stick in the center of the cockpit and the dual throttles near the right and left side walls.

If it sounds to you like there's a philosophy of construction at work, here, you're right. To Chris Heintz, the idea is to make a sturdy, practical, and easy-to-build components. Consequently, some of the components on the plane, such as the welded-chromoly y-handled stick, for example, have a decidedly homemade look to them. Zenair's components do everything more expensive stock components would do (except get brittle and crack after a few years in the sun), but they do it at a quarter of the cost and with three times the durability. It's more than philosophy, too. The CH 701 delivers.
Of all the very light aircraft being produced today, perhaps it's the 701 which borrows most fully from both ultralight and production aircraft traditions. In its basic shape, the 701 is as conventional as any Cessna on the ramp, with tractor engine, high wing, tail-in-back, all-metal, three-axis control configuration.
In performance, however, the 701 is a whole different kind of airplane, with startlingly short takeoff runs and hard-to-believe slow-speed capabilities. In a word, it's all ultralight here.
If the 701 is beefy in all the right places, it's light in all the other spots. This fact accounts for the plane's unique feel. The plane weighs just 460 pounds empty, so it's two-place ultralight legal in US, though the company sells the vast majority of its planes as Experimentals or Canadian Advanced Ultralights.
An example of intelligent minimalism: The doors of the plane are Lexan with light aluminum tubing frames and they, as everything else on the plane, serve their purpose. They're durable, easy to build and provide plenty of sunlight.
Though I've photographed it several times, I didn't get a chance to fly the 701 until a few months back when I visited the Zenith factory in Mexico, Missouri. There I got the chance to go flying with Chris' son and Zenith pilot and Production Manager, Nicholas Heintz.
Inside the cockpit are the two pilot seats, each with good access to one of two side-mounted throttles and the welded chromoly stick. The use of the y-handled stick, instead of two separate ones, is an unusual choice in a light sport plane. But then again, the 701 is an unusual plane in a number of other ways, too. Even the throttle is a simple affair, a piece of steel rod with a "T" welded onto the end. Functional and impossible to break. Dual rudder pedals and brakes (optional on the right) are likewise constructed at the factory out of strong, simple materials, in this case, chromoly tubing. Besides, crashworthiness and entry and egress form the aircraft are improved with the Y-handled stick.

The day of our flight was a dark, threatening one, and we worked our flight in as soon as the sky cleared in the morning and before the T-storms wandered through in the afternoon. We donned headsets (it's loud without them), fired up the 582, taxied past the row of typically Midwestern T-hangars next to cornfields and made our way out to the active runway.
It's fairly tight inside the cabin, though for Nick and me, both of average size, there was plenty of room. Steering on the ground is via differential braking 16-in wheels and hydraulic brakes are standard equipment, and there's nothing, to it.
Once out at the takeoff end of the long paved runway at Mexico (total overkill for this airplane), we went through the plane's simple pre-takeoff check, looked for all the other traffic that was nowhere in sight and rolled out to go flying.
Two things about the 701 that became immediately apparent to me on the takeoff roll were the plane's mind boggling slow-speed flying capability and the light feel of its elevator. It was hot and muggy out there that day, but no more than a couple hundred feet later, we were flying out of around effect. I was careful, as I always am with an unfamiliar airplane, not to rotate too aggressively lest the earth do that smiting thing, it's known for. Even with a gentle touch, we started climbing briskly right off the bat, and I relaxed a little of the slight back-pressure I was holding.
With two aboard, full fuel, and high levels of mercury in the thermometers (high 90s, with humidity to match), I didn't expect any earth shattering climb performance from the 701 and I was right. It did climb out very solidly though, at 500 or 600 fpm, which is a lot better than any Cessna 152 would have done that day on a lot more horsepower.
In retrospect, if I were to operate a 701 regularly under demanding conditions, I think the two-stroke Rotax 618 with its ten more horses would be a natural for this airplane. The four-stroke 912, on the other hand, would transform the 701 into a much quieter, even better-performing airplane than it already is. Still, the engine I was flying was a 582, and it was no slouch.


The STOL CH 701 features wide doors on both sides and plenty of interior room.	The factory demonstrator 701 which I flew is outfitted with the Rotax 582, though both the 912 and 503 are good alternatives depending on your applications.

Up in the air, Nick watched as I did the usual routine, slow flight, stalls, both power-on and power-off, steep turns, dutch rolls and the like. The airplane can fly at a crawl. Waiting for the stall to arrive is like waiting for the end of your first opera; you think it's never going to come!
The CH 701 STOL handles more like an ultralight than a production aircraft, with a high degree of built-in drag - flaperons, and leading, edge slats and don't forget - the associated adverse yaw.
So if you're looking for a really fast airplane, the 701 ain't it. Though lots of people fly the plane cross-country, if that's your thing, I'd recommend the company's CH 601 Zodiac. With the 701, the same things that make it fly so slowly conspire against it in the speed department. It's no slower than most aircraft in its class (the company claims a cruise of 75), but it will fly a good deal more slowly. In my book, that's a net gain.
By the time I got done with the routine at the practice area, the bottoms of the clouds were no more than 800 or 900 feet off the deck, and they were doing nothing but getting lower. Rain was imminent. If we went right back to the field, we'd have time for a few more touch and goes, so I turned the plane north and headed back to Mexico.
Where the aerodynamics of the plane come in to play are at the low end of the scale. It's here that the 701 shines, as I found out when we shot a couple of landings and later when Nick made some slow-speed fly-bys off the grass strip while I photographed the plane from the ground. Like many planes in its class, the 701 comes in nicely and predictably with a little power. Full stall landings will give you remarkably short landing performance, but make sure you hit the flare right on. Then again, if you're a foot or two too high, the gear will probably take it.
Though it wasn't on the airplane I flew back in Mexico, a new all-terrain gear is now standard on the CH-70 1. The gear is similar in design to that of the older gear, but utilizes a direct attachment of the wheel to the main gear spring and the use of 8.00 by 6-inch wheels and 16-inch tundra tires. The nose gear maintains its bungee-suspension design while adding the same hefty wheel/tire combination as the mains. Independent hydraulic disk brakes are also now standard on the airplane.
When you think about it, the landing gear of the 701 must sell a lot of planes for the company. Whereas taildraggers can be hard to handle in a crosswind, or just plain hard to handle for some pilots, the tricycle gear of the 701 is nearly foolproof. And because it's set so wide, you'd be hard pressed to make anything but decent landings.
Back to the simple component philosophy. The use of uncomplicated, factory-built components results not only in a strong, durable piece of equipment, but an inexpensive one, as well. The cost of the kit - minus engine, instruments and finish coat - is just $11,670. If you've checked kit sticker prices lately, you know that the CH 701's price tag is a couple thousand dollars less than most planes in its' class.
Its low cost has evidently attracted lots of customers. The company reports that more than 350 CH 701s have been successfully built and flown. A good number of those fly in the summertime on Zenair's very pretty amphibious floats. Zenair recommends the Rotax 912 for floatplane use, though the 582 worked fine for floats for years before the 912 came out.
Doubtless, the reason for the kit's success can be summed up in a word, value. With the 701, you get a good flying airplane at a great price. What more could you ask for?