Every Light Sport & Ultralight Flying magazine reader has probably heard of off-road vehicles. How about an “off-airport” flying machine? You may not have used the term but you probably know one of the candidates: Zenith Aircraft’s highly functional CH 701. No one calls the CH 701 the most handsome aircraft in the fleet. That title may be better reserved for sleek carbon fiber jobs. But as a practical aircraft appealing to ultralight enthusiasts, the Chris Heintz design with a 20-year history is head of its class. While the design has not changed much in those two decades, the kit has changed quite a bit to make the builder’s effort easier. The designs of engineer Chris Heintz have been around a long time, beginning with his early Zipper ultralight-like aircraft. A prolific and versatile creator, his aircraft models have put nearly 3,000 builders in the air. The low-wing CH 601 series is the most popular at better than 60% of all Zenith models followed by more than 700 CH 701’s now flying around the world.
|Empty weight||580 pounds|
|Gross weight||1,100 pounds|
|Wing area||122 square feet|
|Wing loading||9.0 pounds/square foot|
|Useful Load||520 pounds|
|Payload (with full fuel)||400 pounds|
|Cabin Interior||41 inches at shoulder|
|Fuel Capacity||20 gallons|
|Baggage area||40 pounds, cabin shelf|
|Kit type||Construction kit|
|Build time||350 to 400 hours|
|Standard engine||Rotax 912|
|Power||80 hp at 5,800 rpm|
|Power loading||13.8 pounds/hp|
|Max Speed||95 mph|
|Cruise speed||80 mph|
|Stall Speed||30 mph|
|Never exceed speed||110 mph|
|Rate of climb at gross||1,200 fpm|
|Takeoff distance at gross||90 feet|
|Landing distance at gross||150 feet|
|Range (powered)||400 miles - 5 hours|
|Fuel Consumption||about 4.0 gph|
|Standard Features||80-hp Rotax 912, with electric starter, stainless steel exhaust, radiator, and 3-blade Warp Drive prop; dual 10-gallon fuel wing tanks (20 galoms total); wide, dual doors; independent hydraulic brakes; mechanical flaps; 16-inch tundra tires, removable wings (also see options); complete engine instrument package (Rotax); fully enclosed cabin; in-flight trim; sturdy single piece landing gear construction; steerable nosewheel; all-metal wings, tail, and fuselage; seat belts with shoulder harness.|
|Options||100-hp Rotax 912S (as tested) and several other engine sizes and brands; additional fuel tanks (40 gallons total); electric trim; folding wings; amphibious or straight floats; cockpit-widening "bubble" doors (add six inches of effective cabin space and more visibility); navigation and strobe lights; cabin heat (with Rotax engine); additional instruments.|
|Construction||All-metal airframe, wing, and tail; many skins predrilled; factory-riveted wing spars and lower cabin frame sides; fiberglass fairing. Kit components made in the USA; sold by U.S.-owned company.|
Cosmetic appearance, structural integrity, achievement of design goals, effectiveness of aerodynamics, ergonomics.
Pros - Short takeoff and landing (STOL) design uses fixed slats to achieve excellent performance. Highly functional aircraft; can operate easily from short, unimproved strips. More than 20 years of field experience with more than 700 CH 701's flying.
Cons - If you're looking for sleek or pretty, the CH 701 isn't your bird. Not fast enough for regular, long cross-country flights. Available only in kit form at present (though cost is therefore lower). Builder remains the "manufacturer" indefinitely.
Subsystems available to pilot such as: Flaps; Fuel sources; Electric start; In-air restart; Brakes; Engine controls; Navigations; Radio; (items covered may be optional).
Pros - Flaps, trim, electric start, differential brakes are all standard on the CH 701. Fuel (20 gallons standard) contained in the wings, away from occupants. Engine access through easily removed cowling. Generous useful load allows adding optional equipment without losing utility.
Cons - Flap handle proved challenging for me to deploy to the last notch (though this may have been a fact of the new, test aircraft). Trim control located only on left half of stick. Flap position must be checked via lever position or visual; no indicator (though builder could add it if desired).
Instrumentation; Ergonomics of controls; Creature comforts; (items covered may be optional).
Pros - With "bubble" doors, the CH 701 is adequately roomy for all but the largest occupants. Baggage space in hat rack position. Very easy entry through wide doors; good for larger or less flexible occupants. Shoulder belts standard. Doors secure well. Reach to panel is good.
Cons - Cabin is modestly wide compared to many LSA (though "bubble" doors add effective width). Center joystick tended to hit right-seat occupant in flight (though I was deflecting more than most normal inputs). Interior is rather Spartan unless builder elaborates.
Taxi visibility; Steering; Turn radius; Shock absorption; Stance/Stability; Braking.
Pros - Strong, differential brakes aid ground handling. Gear and structure can handle fairly rough terrain. Skylight adds good upward visibility for traffic checking prior to takeoff. Landing gear easily able to handle fairly rough terrain. Good ground clearance.
Cons - Lateral visibility is less open than in the bubble canopy CH 601. Test aircraft had brakes only on the left; going dual will add some cost and weight. No other ground handling negatives.
Qualities; Efficiency; Ease; Comparative values.
Pros - Takeoff is very rapid and requires a very short distance, perhaps the model's top attribute; ground roll is only 100 feet and rotation starts almost immediately, thanks partly to leading edge slats. Approach speeds can be very slow with practice, good for the shortest field landings.
Cons - Landings have a slight challenge that demands a little practice; you must keep the nose up once lifted or the CH 701 merely resumes flying. Sink rate after power retarded is quite high (1,000 fpm); this is a useful design feature allowing STOL landings, but you have to anticipate.
Quality and quantity for: Coordination; Authority; Pressures; Response; and Coupling.
Pros - Aileron forces were very pleasant and responsive. Efficient rudder control surface, a full flying design (but see "Cons"). Pitch forces were light without being sensitive, a good combination. Control forces at very low airspeeds permitted by wing/slat design were reasonable.
Cons - Control harmony hard to check in test aircraft as rudders were still tightly adjusted; tended to stick slightly (though possibly only on this aircraft). Wing can fly so slowly that controls necessarily become more sluggish due to low airflow.
Climb; Glide; Sink; Cruise/stall/max speeds; Endurance; Range; Maneuverability.
Pros - Terrific takeoff performance, better than all but the very lightest ultralights. Climb very strong at 1,000+ fpm at gross. Very capable airplane for low-and-slow flying over landable terrain; extremely slow speeds (in the 30s) with practice and caution.
Cons - Rather high idle thrust sink rate (1,000 fpm); neither glide is very long (though this is considered a deliberate design feature for a STOL airplane). Cruise speed of 80 mph won't carry you too far. Fuel at 20 gallons standard is four hours or less (though sufficient for most operations).
Stall recovery and characteristics; Dampening; Spiral stability; Adverse yaw qualities.
Pros - Mild stalls at most angles and speeds (though see "Cons"). Longitudinal and lateral stability appeared very normal in all tests. Response to power input/decrease from trim flight was positive and predictable with few oscillations.
Cons - Stalls with the 100-hp CH 701 (as tested) can be done aggressively enough to cause a sharper break (though recovery remains quick and simple). Adverse yaw was quite significant, something to be remembered at very low speeds the CH 701 can achieve.
Addresses the questions: "Will a buyer get what he/she expects to buy, and did the designer/builder achieve the chosen goal?"
Pros - Longtime, well-proven supplier (est. 1992) gets excellent comments from customers for technical support and customer service. Can be flown by Sport Pilot certificate holder. Can get airborne with good basic equipment for about $35,000 (and 400 hours of your labor), far less than many light sport aircraft.
Cons - Not a Special- or Experimenta light-sport aircraft (yet), so Amateur-built rules mean builder always remains the "manufacturer," with attendant legal responsibility. Build time is 350 to 400 hours (though factory support can ease the burden). Even $35,000 is more than some ultralight kits (though with 4-stroke engines, it will be closer).