Super Duty!

Zenith takes the STOL CH 750 up a notch.

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What do you get when you take an LSA bush plane and put an Aero Sport Power IO-375 on the nose? You get a machine that is ready to take on the world—a world of short strips, sandbars, and mountain meadows. Zenith Aircraft started with a STOL CH 750 aircraft, lengthened the wings, enlarged the tail, beefed up a few things here and there—and created a new model called the Super Duty. Think of a real pickup truck, not one of those fancy citified vehicles. We’re talking about something that you can throw the tools into and go running off the landscape to patch a hole in the fence. The Super Duty is that kind of machine, with the muscle to get you there and back.

Getting rid of the instrument panel opens up a huge amount of space in the SD cockpit. The glass panel can be positioned wherever the pilot wants it to be. Note the stalk for the throttle on the far left side of the cockpit.

Introduced at AirVenture 2017, the Super Duty was a surprise to almost everyone that walked up to it. Zenith did a good job of keeping the project under wraps until they were ready for the big reveal, and it was a surprise in more ways than one. Not only did it sport the big engine and sit on large tundra tires, it also featured one of the most unique innovations of the year—the “Unpanel.” This out-of-the-box concept does away with the traditional instrument panel, substituting instead a single glass-panel EFIS mounted on a moveable arm so that it can be positioned in front of either the pilot or passenger, or moved out of the way of both. This isn’t just getting rid of instruments; it does away with the entire instrument panel structure, a very unusual idea.

The Avilution EFIS is developmental and while not fully functional at the time we flew it, will eventually control radios and transponder using edge buttons and knobs.

The Super Duty concept really is a response to the new BasicMed regulations from the FAA that allow pilots to keep flying airplanes that are well outside the original Light Sport parameters. While kit designers and manufacturers have been producing airplanes that fit the weight, horsepower, and speed restrictions ever since the category was invented, it didn’t stop pilots from wanting more. With BasicMed, pilots can more easily keep flying without the threat of being grounded for failing a Third Class medical exam and still fly airplanes with the payload and speed capability they want.

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We are seeing a revolution of sorts as manufacturers across the board are bringing their LSAs forward with more power and higher gross weights. This is Zenith’s entry into the new paradigm, and while they have sold kits for larger, more capable airplanes before (the Zenair STOL CH 801 for example), this is the newest design from the company that will serve the developing “post-LSA” market.

We got a chance to fly the Super Duty two days after it debuted at AirVenture, and here is our report.

The Super Duty uses fixed slats, just like the STOL CH 750.

Features and Details

If you’re used to the standard STOL CH 750 or the Cruzer, the Super Duty is going to seem bigger when you first approach it. The truth is, the fuselage is virtually identical to its older siblings, but the fact that it is sitting on larger tundra-style tires makes it sit higher. The cowl is also larger to accommodate the bigger engine, and the tail surfaces are larger as well. The wing is a bit longer, but it is challenging to determine airplane size just by looking at the wingspan, so this probably isn’t a factor.

The center console holds all the necessary switches and controls except for the throttle, which is on a stalk for the pilot’s left hand.

The next thing you are likely to notice is the unusual instrument panel configuration. As we’ve already mentioned, it doesn’t have one. Instead of the usual panel, there is empty space all the way to the firewall. This empty space is home only to an articulated arm assembly supporting a single, large-screen EFIS panel. The factory prototype is fitted with the Avilution EFIS, but it probably won’t be very difficult to build the same concept with your choice of EFIS. Basically, you will be building a simple box in which the screen(s) mount, with a few wires running down the articulating arm, and all the avionics mounted remotely.

Since there is no instrument panel, Zenith mounted circuit breakers in a strip under the passenger’s legs. The position works very well.

The articulation of the screen allows you to place it wherever you want—in front of either front-seat occupant, with the height adjustable to where you like it. Remember the throw-over control yokes in older Bonanzas? Just think of this as a throw-over panel. If the panel is in the way, you can also push it forward and down, so that the view is uncluttered. And speaking of the view—with the solid instrument panel gone, the windshield continues down the sides of the aircraft where there would normally be skin. The effect is almost like flying an old bubble-cockpit Bell 47 helicopter. Zenith visibility out the bubble-windowed doors has always been good, and now it is even better.

It’s odd to actually see rudder and brake pedals in a light plane because they are usually tucked under the panel. With no panel, the SD cockpit is more like a helicopter.

Doing away with the instrument panel sounds simple when you have done away with all of the instruments. But there are other things on a typical airplane that also mount there. Take circuit breakers or fuses for instance—where will they go? Zenith has a clever solution in the Super Duty, mounting circuit breakers in a strip just ahead of the passenger’s seat, right under their legs. One observer noted that it might be hard to find and identify a particular breaker with that location, and they may be right. But good practice is usually not to reset popped breakers in flight anyway, so it might be a more theoretical than practical problem.

Next up—with no panel, where do you put the throttle? Zenith has this solved with a curved stalk of tubing coming up from the floor/firewall junction, curving back to the pilot’s left hand. This is almost a sci-fi solution when you look at it, but it is simple and elegant. It does, however, present a problem for the right-seat pilot/passenger, since they fly the single center stick with their left hand and can’t really reach across with that hand and fly with their right—at least not with any elegance. Zenith will probably find a similar solution to the existing throttle by adding one to the right, something they do with most of their aircraft already. The configuration we flew was done to get the airplane ready for AirVenture, and they know they want to work on it.

The rear seat is designed to hold 200 pounds—or the equivalent weight in baggage.

As mentioned above, the primary flight controls for pitch and roll are on a shared center stick between the two front seats, with a Y-shaped handle so that each front-seat occupant has their own grip. Flying from the right, I thought the angled hand position on the left was familiar and soon realized that it felt much like the side-stick controllers for the pilot on many modern jets. It was actually very comfortable and easy to fly. Standard rudder pedals with brakes will be the most familiar flight control in the cockpit for most pilots—the only difference being that you can actually see your feet, since they are not hidden under the panel.

Now take a look behind the front seats—yup, that’s a third seat back there! The baggage area is standard size for a CH 750 fuselage, but there is plenty of room for one person, and I suppose if you put in the necessary seat belts and only carried small, young folks back there, you could convince yourself it was a four-seater. According to Zenith, they are expecting a final baggage/rear seat capacity of about 200 pounds, so think about how you’d like to use it. Zenith does have plenty of experience with rear seats by the way—the Zenair STOL CH 801 (Zenair is Zenith’s sister company in Canada) is a full-up four-seat airplane that has been available for many years.

The Aero Sport IO-375 puts out 205 hp—by far the most ponies Zenith has put on a two-seater.

Up front, of course, you’ll find something unusual for a Zenith 750—a big IO-375 engine producing 205 hp, put together by Aero Sport Power. A stroked IO-360, the 375 has been proving itself in a number of airplanes in recent years, and so far has a good reputation for power and reliability. Engine operation and management will be familiar to most pilots that have flown traditional flat-four Lyclones, and installation, cooling, and systems will all be just as they are used to.

The firewall-forward installation will look familiar to anyone used to working on Lycomings.

The aircraft currently has a large, wooden fixed-pitch prop installed. According to Zenith president Sebastien Heintz, it was “what we had hanging on a wall.” However, we can easily see it having an even wider performance range as soon as some builder decides that what it really needs is a constant-speed motivator up front. I’m sure that won’t take long.

Flying the SD—Fun Performance

Upon entering the Super Duty, the first thing I thought was, this thing is roomy! The combination of Zenith’s bubble Plexiglas doors and the lack of the instrument panel combine to make the airplane feel even more spacious than its lower-powered siblings. The center stick (between the two seats) keeps the area in front of each person clear, and if the panel is in the way, you can always reposition it. Visibility is further enhanced by the full greenhouse roof—there are probably very few high-wing airplanes with such good sight lines.

The full-span flaperons are the same as used on the standard STOL CH 750, just a bit longer.

Test and demo pilot Roger Dubbert of Zenith Aircraft and I pushed the airplane out of its show spot in “Homebuilder’s Row” at the crack of dawn, feeling like a bunch of kids taking their dad’s car for a joyride. We had a join-up time with a photo ship north of Oshkosh we were trying to meet, and the hour from 06:00 to 07:00 is actually a wonderful time to fly at the big show—departures only, no arrivals to contend with. Firing up the fuel-injected Aero Sport was no problem: a little prime with the fuel pump, mixture to idle cutoff, throttle cranked, then a sweep of the mixture control to full rich when it fired off. The engine controls and switches in the Super Duty are simple and standard for this type of powerplant and will be instantly familiar to anyone that flies an injected Lyclone.

Steering was positive on the taxi, and braking was good. We completed the runup on the way to the departure end of Runway 36 Left and waited for clearance to depart. The early-morning hours meant that there were no pink-shirts on the ground, so we were actually cleared to go by the guys in the tower itself—a brief period of normalcy in the otherwise unusual world of AirVenture ATC.

he tail looks just like that on the STOL CH 750, but is actually a bit larger to handle the increased engine size and larger wing.

In the interest of moving quickly off of KOSH, Dubbert managed the takeoff, and we were airborne in just a few plane lengths—just as you’d expect from a normally STOL-ish airplane that had a large injection of horsepower. I took control shortly after and noted light pitch forces in the initial climb, something I had been warned about beforehand. Zenith is still working on control harmony, and since they have worked this out on their other models, I have no doubt they’ll have this nailed quickly in the Super Duty as well. Roll control was about what I expect from a 750, even though the wings are longer, and the rudder felt quite normal and well matched to the airframe size and weight. The pitch trim switch is currently mounted on the forward center console—a little inconvenient when flying with the center stick, as you need to operate it with your free hand, which will always be reaching across your body. It’s a minor thing, easily fixed with a trim-equipped stick grip.

Vortex generators on the underside of the elevator only come into play at large control deflections and are very effective.

Since we had departed from Runway 36 and had to exit the AirVenture vicinity to the southeast, we had plenty of time to evaluate the handling characteristics on our way to the photo rendezvous on the northwest side of Oshkosh. What I felt was a very normal airplane with good stability and excellent visibility. Engine parameters were well behaved, with temperatures for cylinders and oil doing fine. We slid the instrument panel around into different positions, just to see what it looked like, and the ability to do this and get it out of the way when we wanted was quite handy and very unique.

Rolling the airplane into a couple of steep turns, we found that it was easy to stay on altitude and keep things coordinated—nothing unexpected here. Slowing down for a couple of power-off stalls, the airplane responded with a little buffet, but no break. It just settled into a sink rate with a slight bit of bucking to let you know that it wasn’t happy about the situation, but it wasn’t going to bite. The factory was still working on adjusting the flaperon linkages, so we were limited in overall travel, so we didn’t do anything with full deflection—but just a few degrees of flaps lowered the stall speed by a few knots and made for a nice landing approach.

The rugged nosegear has a large tire to match the tundra tires on the mains.

With a little time on our hands before the photo ship rendezvous, we shot a landing approach to a 3000-foot paved strip hidden between Oshkosh and Appleton. Dubbert and I had flown together before, which was good, since I was flying the airplane, but he was handling the throttle. We set up for what amounted to a power-off approach from the low key position on downwind, and that way, all Roger had to do was add a little power if I felt we were getting low. The airplane handled smoothly as a glider, and I slipped off a bit of excess energy to a nice touchdown on the first try—tundra tires can do that for you. Adding power, the airplane was off the ground quickly and back in its element with no complaint. I have always enjoyed doing short takeoffs and landings in the Zenith airplanes, and the Super Duty lived up to its lineage.

The large tires give the Super Duty the ability to land on rough and even unprepared surfaces.

Meeting up with our camera ship, I turned the airplane over to Dubbert (since he had the throttle) and got a chance to really look around at the green fields and marshes of eastern Wisconsin. If looking at the ground from an airplane is your thing, the Super Duty is your airplane. No matter where you look (except straight down or straight back), you have a good view of the outside world. In formation, the airplane was solid and stable, and as you can expect, there is no substitute for horsepower!

We did a couple of additional landings to go and get fuel before returning to the busy AirVenture environment, and each landing was a delight. The excellent visibility allows you to maintain a view of the touchdown point pretty much right up until you plant the mains—then you just want to add power and go do it again because it is so much fun.

Since the airplane had finished Phase I testing only days before AirVenture, where we were flying it, and it only had the flight from Mexico, Missouri, to Wisconsin as additional time on the clock, there were still a few things that Dubbert was figuring out. The built-in com radios for the Avilution panel were not yet functional, for instance, so instead we had a portable intercom hooked up to a handheld radio to manage communications between us, a photo plane, and the busiest control tower in the world. But it worked. The electric trim was running just a little fast—nice when you wanted an abrupt trim change, not so nice if you were trying to fine-tune a trim position. This is typical of new-airplane tuning and easily fixed. And they are still tweaking the flap mechanism to allow for full deflection without stiffening up the ailerons. But for an airplane with as many new features as the Super Duty it was remarkably mature at this point in its life.

From our experience with Zenith, this will be a fine airplane that many will find suits their needs. It’s an honest airplane with plenty of power and good handling characteristics.

In the final rush to have the airplane ready for Oshkosh, Zenith didn’t have time to experiment with different props. The big wooden Sensenich is something they had on the wall—they’ll be doing prop optimization in the near future.

Kit Features and Availability

Even though Zenith kept the Super Duty as a surprise until the first day of AirVenture, the kit is available to order immediately, according Heintz. It really wasn’t hard for the company to do that, since most of the parts are identical to those found in the other 750 models.

According to Heintz, “98% of the fuselage parts are common, which is the reason we’ve kept the CH 750 designation and added SD to it, rather than a full new name. We used the same fuselage because it is already very roomy with great visibility, and also because we now offer it completely match-drilled to final hole size and ready to assemble out of the crate.”

The ease of assembly and attention to detail is quite impressive when compared to earlier kits and represents a huge amount of engineering work in SolidWorks and with CNC manufacturing. Most of the actual differences with other 750 models are in the rear baggage area with the jump seat.

We also asked if those who are already building a 750 and have that “Super Duty” urge could change to the new design. Heintz replied that conversion is definitely possible because of the shared lineage.

A Backcountry Player

Ironically, while the Light Sport designation was a remarkable catalyst for a number of today’s popular kit aircraft, it has, in some ways, held back the full development of the various lines. The Super Duty is a great example of that—an airplane designed to meet the weight, power, and speed limitations of LSA, now sporting 205 hp and increased carrying capability.

That extra horsepower translates directly into climb performance, something every backcountry pilot is looking for, whether they are getting in and out of short strips in the flatlands, or climbing out of rough strips carved out of the mountains with high density altitude. The Super Duty should handle both of those situations very nicely, giving more pilots access to the untracked parts of the planet.

The rugged designation of the Super Duty is just right, in our opinion, and one of these days, we’ll talk Heintz into letting us borrow one for a few days of traipsing around the high country, just to prove that it can do the job. I’ll tell you a secret though: We just want to go have fun! We already know the plane can handle it.

For more information, visit www.zenithair.com. Videos and additional photos can be found here.

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Paul Dye
Paul Dye, KITPLANES® Editor at Large, retired as a Lead Flight Director for NASA’s Human Space Flight program, with 40 years of aerospace experience on everything from Cubs to the Space Shuttle. An avid homebuilder, he began flying and working on airplanes as a teen, and has experience with a wide range of construction techniques and materials. He flies an RV-8 that he built, an RV-3 that he built with his pilot wife, as well as a Dream Tundra they completed. Currently, they are building a Xenos motorglider. A commercially licensed pilot, he has logged over 5000 hours in many different types of aircraft and is an A&P, EAA Tech Counselor and Flight Advisor, as well as a member of the Homebuilder’s Council. He consults and collaborates in aerospace operations and flight-testing projects across the country.

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