In June of this year, I found myself flying low in my Toyota pickup on a road trip bound for Yellowstone National Park to celebrate my wife's parents' 40th wedding anniversary. It was a wonderful time with family, but despite my best effort to resist, I could feel the pull of the airport. Every pilot knows how this works; the ridicule we endure from our families or friends or TSA when we drive into a new-to-us local airport just to "check it out." One of the perks of BackcountryPilot.org is that you end up with friends in every town in the country, and in this case it was time to pay a visit to my old buddy Ben Haas to finally lay eyes on his bold and beautiful Zenith STOL CH801, now that I was in his backyard of Jackson Hole.
The author playing tourist at the top of Rendezvous Mountain, Jackson Hole Mountain Resort (10,449'); 3,000 ft higher than the highest altitude achieved during the flight of the Beast.Photo: Erin Halley
Ben invited me to accompany him on one of his daily low-level patrol flights, performed on special waiver from the National Park Service, to monitor irrigation systems of the area. Apparently, Jackson Hole airport is one of the only commercial airports located within a national park (Grand Teton) in the United States, so this is a unique situation in every way. The weather all week had been horrendous, but Friday finally cooperated with some clear skies.
Ben Haas, aka user "Stol" on BackcountryPilot.org, was one of the earliest members, having joined in 2005. It could be said that few people seeking discretion or anonymity paint their aircraft bright orange and power it with a screaming 400 horsepower Ford racing engine, and so his legend in the community quickly developed based both on his incredible aircraft and his outgoing personality. I'd met Ben once before at Johnson Creek years ago, but I was excited to finally get to fly with him.
A little background on Ben: He moved from Coral Gables, Florida to Jackson, Wyoming in 1989, and having sold his Piper Warrior and Aerostar, found himself looking for something a little different (and perhaps less expensive) than the certified aircraft to which he was accustomed. As one could imagine, the rigid rules and regulations of type certification were at odds with the innovation and constant quest for performance that are embedded in the very soul of Ben's former vocation: NASCAR race driver and engineer.
In 1991 the 4-seat Zenith CH801 kits had just hit the market and seemed like the perfect aircraft to explore his newly chosen home area: the highlands of Jackson Hole, with valley elevation well above 6,000 MSL. The surrounding mountains and high terrain of the Tetons top out around 13,370 MSL. In the mountains, power is king, and after exhausting other options like vaporware diesels and uncertain Franklins, the obvious choice soon became to hang a race motor, and thus the engineering project that is an auto-conversion began.
The 400 horsepower all aluminum Ford 347 V8 at the heart of this aircraft wasn't actually Ben's first choice. He'd held out for the Deltahawk diesel as long as he could before he gave up hope and went with what he knew well: NASCAR technology. And even while he's more of a Chevy guy, he went with the Ford because it's a slightly more compact package.
His motor is capable of 800+ HP, but it's detuned to around 400 HP and in Ben's words it's "dangerous." With a concerned pause I asked him to clarify what he meant by that statement, and he alluded to the fact that with such an abundance of power, the aircraft will easily "hang on the prop" during a full power takeoff, well before enough airflow over the wings and control surfaces make it flyable and controllable, as well as some serious torque-rolling behavior. With great power comes great responsibility in using that power, especially in a serious slow-flying wing like the Zenith.
NASCAR meets aviation...Photo: Ben HaasSince auto engines are generally designed to make power at higher RPMs, their output must be reduced to the appropriate range for propellers, which are limited to about 2,800 RPM to maintain their effectiveness in the medium of air. This reduction is done using a Propeller Speed Reduction Unit, or "PSRU." Ben went with an off the shelf unit from Belted Air Power out of Las Vegas, which puts his reduction at 1.43:1, but ended up making some serious changes to nearly every component in order to make it more robust and capable of handling the massive power of the Ford. This particular engine puts out max power at 4,600 RPM, which equates to a prop RPM of about 3,200. That's pushing it, and so most takeoffs are performed at about 70% power, backed off to 55-60% for cruise, resulting in about 95 mph.
One thing I should be reprimanded for is not taking a photo of the engine with the cowling off the airplane; Ben even offered, but I was too excited to go fly it and so I declined. Luckily, the power of the Internet allowed me to locate a photo Ben himself had taken a few years ago. The installation is a thing of pure beauty.
Ben's CH801 build began in 1991, prior to the introduction of the fast-build kits, and he estimates around 900 hours for the firewall-back portion. The engine and prop of course were an entire project of their own, an iterative process that delayed the first flight until 2004, almost 13 years after construction began.
Aside from a few small things, the build remains very close to the original design. Ben did replace the thrust bushings for the "Y" shaped control stick with custom machined titanium versions, resulting in a very tight and responsive feel. He also developed some spacers for the wheel/brake attachment that avoids having to mill material from the ankle of the aluminum spring gear, which would weaken them somewhat. Aside from these few changes, Haas is a firm believer in the design of the 801 airframe and sings the praises of Chris Heinz.
When asked if he would choose the 801 again if building today, his answer was "no." He would choose the slightly more diminutive CH750 and build it to conform to the LSA regulations; a very common answer these days.
Performance and demo flight
I wish that I had more Zenith hours logged prior to flying with Ben so that I could provide a comparative testimony for the extra power, but alas this was my very first Zenith flight. So for you experienced and knowledgeable Zenith pilots, please excuse my naïveté.
The Y-stick is great! It's a very egonomic solution to the control stick, and keeps the area between your legs clear as there's only a single stick shared by both pilots. It also solves the side-by-side issue by allowing the PIC to sit left seat while using right arm on the stick and left on the throttle, one of the things this right-hander has always loved about tandem aircraft.
The Zenith had a much more nimble feel to it than I was expecting, with a healthy roll rate and powerful rudder. One would expect a slow-flying thick chord wing like this to be somewhat lumbering and slow to respond, but it was not what I expected. I felt the same way about the Just Highlander when I flew it for the first time, which says more about my inexperience in these designs than anything. Perhaps my time in old Cessnas and Cubs has set my control responsiveness mark a little low?
The power was definitely impressive, and any other takeoff in an aircraft of this weight and utility from 6,451' above mean sea level (I later roughly calculated 7,500 DA based on 55 F @ 30.16") would have been mediocre, but as you'll see in the video, we were off the ground and climbing out with a quickness, and that was only at 70% power! I think Ben took it a little easy on me, and I was relieved that I could see over the panel.
After I was satisfied that I'd captured some decent cockpit video footage, Ben had me fly a teardrop flight path to the south, out over the town of Jackson to observe a house that had recently been split in half by a landslide. I put the aircraft into about a 70 degree banked steep turn to execute a 180, and it just sort of did all the work. I expected more adverse yaw, so I really stepped hard on the rudder and ended up overcontrolling the aircraft. Ben never reprimanded me though, and just allowed me to enjoy it.
One thing that should be part of any STOL aircraft flight test is some slow flight and stalls. Once again, in my haste to play videographer, my attention moved outside the cockpit and to the surrounding terrain of the Tetons, and I just plain forgot to collect more mental data about the flight characteristics. We retraced our steps back to the north and toward the airport, patrolling the system of irrigation ditches and waterways that are Ben's daily flight duty.
The approach and landing were interesting, and even though Ben commented on it before hand, I was struck by how much power he left in for the approach. The Zenith wing is so draggy that a power-off approach is an incredible steep experience, which is probably good; not to start an argument or anything, but modern consensus favors the steeper level-AOA approach over a shallow power-on one. The Zenith excels at this technique. However, in the video below you'll notice we used the shallow approach, and Ben nailed his spot landing. Maybe not the shortest (hey this a 6,300 ft runway,) but he prides himself on nailing his spot.
It probably didn't help any that we were sandwiched between arriving and departing private jets.
|Type||Zenith Air CH801|
|Year||Project began 1991, completed in 2004|
|Engine||840 HP NASCAR grade V8 Ford 347 detuned to approx 400 HP
|Propeller||IVO 84" Magnum 3-blade in-flight adjustable|
|Gear||Spring aluminum main, bungee-suspended nose gear|
|Tires/wheels||8.00x6 all around|
|Wing||Standard CH801 with slats and flaperons|
|Weight empty||1,300 lbs|
|Useful load||1,300 lbs|
|Fuel capacity||66 gal (long range tanks)|
|More airframe specifications can be found at Zenithair.com.|
No featured bush plane piece is complete without some video footage. Ben took me up on one of his survey flights around the Jackson Hole area and let me fly the Beast a little.
Enjoy the complete gallery of photos for N801BH: