(TEXT- Guy Leitch, IMAGES – Garth Calitz and Andre Venter)

A WONDERFUL LITTLE PLANE!

The humble Ercoupe must be one of the most under-rated planes ever. The reason ‘real pilots’ love to heap scorn at it is because it was designed to be as easy to fly as driving a car.

Guy Leitch.

THE ERCOUPE’S DEVELOPMENT goals were ambitious and revolutionary for the 1930s. A two-seater plane that would be safe, and above-all, easy to fly. It had to be stall and spin proof and have a cruise speed of 100 mph – with just a 65 hp engine.

The development of such a plane began in the 1930s, when a small group of engineers at the NACA Laboratories started a private study that resulted in the building of the W-1 and W-1A prototypes having the these for then, very unconventional features:

  1. The tricycle landing gear with castering nose wheel.
  2. Strong longitudinal and lateral stability with limited upward elevator travel to prevent loss of control due to stalling and spinning.
  3. Flaps to reduce the stall speed.
  4. Dual controls for instruction.

Development

In the 1930s light aircraft designers were stuck in the paradigm of rag and tube taildraggers with tandem seating and control sticks.

Stall-spin accidents and ground loops were common so aerodynamicist Fred Weick began experimenting with aircraft designs that would eliminate them. Weick’s first design was called simply the W1 and it won a competition for a stall and spin-proof plane. On the strength of his prize-winning design, he partnered with Engineering Research Company (ERCO) and changed his design to a low-wing model that became the ERCO Ercoupe.

The first flight was in 1937, with production following immediately. The 75-horsepower machines were inexpensive and a step above virtually everything else on the market. As the Great Depression ended, 112 were built, but production was stopped by World War II.

With the end of the war, Ercoupe joined the boom and bust of 1946 to 1948. Five thousand Ercoupes, with horsepower from 75 to 90, were rolled out of the factory in the two years before it closed.

The type certificate changed hands a number of times after that and a total of about 400 more planes were made under the Aircoupe, Alon, and Mooney names, but only those made by ERCO were Ercoupes.

To make an easy to fly plane with car-like ground handling, Weick introduced the then novelty of steerable tricycle undercarriage. To reduce the risk of stall and spin accidents, he combined the aileron and rudder controls and eliminated rudder pedals altogether, making it impossible to fly in an uncoordinated state. The pilot uses the yoke like a car’s steering wheel to steer the plane on the ground.

‘A fun, safe and easy means of getting in the air’

Weick created a sleek aluminium fuselage with twin vertical stabilisers and a canopy that could be opened in flight, so you can wave to groundlings.

The result was a plane that the American Civil Aeronautics Administration (CAA), the predecessor to the FAA— proclaimed “incapable of spinning,” and it earned a reputation as a fun, safe and easy means of getting in the air.

ZS-VCE has a non-standard 115hp Lycoming engine that drives a simple fixed wooden pitch prop.

Construction

Ercoupes of various varieties were manufactured by a handful of different companies between 1940 and 1970, but the vast majority were built by ERCO. They built the first 112 examples in 1940 and 1941 and called it the 415-C. There was no 415-A or 415-B; the C indicated that it was powered by a Continental engine, and the number indicated that the Ercoupe was ERCO’s 415th product.

After a pause in production during World War II, 1946 to 1950 brought mostly minor changes to the plane, and the various ERCO models (415- C, 415-CD, 415-D, 415-E and 415-G) differed mainly in horsepower and gross weight.

In today’s market, the most noteworthy ERCO models are the 415-C and 415-CD. These have a gross weight of 1,260 pounds and are the only Ercoupes that qualify under the 600 kg Light Sport Aircraft rules.

From 1958 to 1959, a company called Forney took over production, renaming the planes the F-1 and F-1A Aircoupe. These were equipped with the Continental C-90 engine and had metal wing skins. Approximately 25 F-1As were produced by Air Products Co. until the company changed hands.

After another pause a company called Alon took over production with the C-90-equipped A-2 Delux. The Alon models sported a bubble canopy that slid back to provide access to the cockpit, which was slightly wider than previous Ercoupes. All had metal wings, and some used spring-steel main gear legs in place of the traditional trailing-link main gear. A total of 297 examples were built between 1965 and 1967.

The final manufacturer of the Ercoupe family was Mooney, which built 59 examples of the M-10 Cadet between 1969 and 1970. The Cadets are perhaps the easiest variants to pick out of a crowd because they stopped using the original’s twin-vertical-stabiliser in favour of the trademark Mooney ‘backwards’ vertical fin – and it had traditional rudder pedals.

The vast majority of surviving Ercoupes are the 1946 to 1948 models built by ERCO, and most were equipped with the 85-horsepower Continental C-85. Our flight test aircraft ZS-VCE had an engine upgrade to the Lycoming 0-235 of 115hp in 1981 and at the same time, the conversion to give it normal rudder pedals. Although it carries a ZS- registration, it is in fact a non-type certified aircraft with the V in the registration representing a vintage aircraft.

The Walk Around

An Ercoupe’s distinctive design makes it stand apart from most other planes parked on a ramp, and its unique features become apparent as you climb into the cockpit. Instead of doors, the Ercoupe has two flexible plexiglass windows that are pulled up from each side to meet in the middle – similar to the cover on a roll-top desk. To get in, simply pull down one of the windows, slide down, and then pull it back up to close it.

‘can be flown with both windows down’

The Ercoupe can be flown with both windows down at any speed, giving it the feel of an open-cockpit plane.

The purpose of the twin tail is to place the rudders outside the slipstream of the propeller, helping to reduce the left-turning tendency. Only the rudder on the inside of the turn deflects noticeably.

The Ercoupe has many amazing features – not least of which is its ability to land at almost any speed. This requires an extra pre-flight item. Check that the nose strut is inflated so that the top of the tail is exactly six feet three inches above the ground. This gives a nearly zero angle of attack at rest. It means that you must rotate on takeoff, but also means that once you put the plane on the ground and lower the nose, it is finished flying.

At around 39 inches wide, the cockpit has about as much shoulder room as comparable two-place planes. It’s still a cozy shoulder overlapping place though, and the baggage area behind the seats is relatively shallow.

Extended trips require careful packing.

The fuel system consists of two wing tanks, a gravity feed fuselage header tank, fuel pump, primer, fuel drains and a filter. The wing tanks (nine USG each) form the leading edge of the wing centre section. The wing tanks are interconnected by a fuel line which allows the fuel pressure and quantity to equalise.

Fuel is transferred by the engine driven fuel pump from the wing to the fuselage tank, and is then fed by gravity through a gascolator to the carb. Excessive fuel pumped to the header tank flows back through an overflow to the wing tanks.

While the earliest Ercoupes lacked electrical systems and, therefore, must be hand-propped, the vast majority now have electrical systems and starters.

The start is standard for a small Continental (or in ZS-VCE’s case, a small Lycoming). Turn on the fuel (there is no mixture control) find the master switch (most are on the shelf behind the passenger), and turn it on; give the engine a few shots of prime, turn on the mags and press the starter. The small Continentals, when in good shape, seem to fire-up quickly the Lycoming tends to shake like an old dog a bit more. With the canopy open, the wind through your hair is a good indication that this little plane is going to be FUN.

A 1942 flight test report of the original single pedal model noted that taxiing is naturally different. On the original unmodified versions, because the aileron and rudder controls are interconnected, you simply drive the plane on the ground using the yoke as a steering wheel. The single foot pedal applies the brakes – hopefully equally. No differential braking is available, but steering on the ground is reported to be easy and precise.

For a small plane it likes big runways. The book says that at gross weight from sea level in standard conditions, the 85 hp 415-E requires 2,100 feet to clear a 50-foot obstacle, and with most Ercoupes weighing around 900 pounds empty, the full-fuel payload can be modest in the LSA-compliant models.

Because of the zero angle of attack stance, you have to pull the wheel back to rotate at about 65 mph. Climb at 75 mph will generate about 500 feet per minute. If you climb too slowly, the P-factor left-turning tendency will mean that you must hold a lot of right wheel, causing significant drag from displaced aileron and rudder control surfaces, and a loss of lift, because the climb takes place with the right wing low, which does not help your climb rate.

The 85 hp Ercoupe climbs poorly below about 70 mph. Most Ercoupe pilots have had experience watching things off the end of the runway get larger rather than smaller. This distressing state of affairs is only aggravated by raising the nose and ruining what leisurely climb is available.

One of the reasons the plane is so loved is that it handles sweetly. It soon becomes apparent that the roll and pitch controls are well harmonised for a plane of this vintage. Like the Slings, it has found that sweet spot between being overly responsive and overly stable.

In turbulence it bounces about, as do all planes with a light wing-loading. It challenges you to hold your altitude; and wallows due to adverse aileron yaw when making small control inputs. Yet, levelled off in smooth air, it more or less stays where you put it and seems, at all times, to be eager to respond should you desire to throw it about a bit. When you fling the wheel over, the roll rate is brisk. Interestingly, a faster roll input keeps the ball in the centre more effectively than do slower roll commands.

‘the feel of an open-cockpit plane’

The canopy provides superb visibility, so travel by Ercoupe is to enjoy the countryside rolling

slowly by beneath the wing. The Ercoupe moves along at about 100 mph, burning a bit over 5 gallons per hour, which is most acceptable for going places without spending your children’s inheritance.

Roll into a steep turn and try to stall the plane. You will not succeed if the elevator is rigged correctly. When full-up elevator travel is reached, the ball will be in the centre, and you will be descending. At altitude the descent may not be easily detected without reference to the altimeter. However, it can become quite significant and get a pilot into trouble close to the ground. The solution is easy, and virtually instantaneous — unload the wing and fly level for a while to gain enough speed to climb.

Landings in an Ercoupe are experiences to be shared. They can be performed in many different ways. Should you be so inclined, and if the nose strut is correctly inflated, you may touch down at cruise speed. When the aircraft is rolling on all three wheels, the angle of attack of the wing is nearly zero, so the plane will remain on the ground. Every owner seems to go out and confirm that the story is true, which it is, although such a landing has to be handled gingerly until you have slowed. Far more pleasant is to approach at about 80 miles per hour, slowing to about 70 over the fence, but no slower or you may not be able to flare without power.

Touchdown on the trailing link main wheels can be one of those “are we down yet?” affairs, for the gear travel is 30 cm. Weick was among the first to discover the benefits of long travel trailing-link main gear, something the rest of the industry did not place into large scale production until the 1970s.

Because of the roll-yaw interconnect, crosswind landings are done by crabbing into wind. The mainwheels do not caster as the trailing-link design simply turns the plane to point in the direction in which it is traveling, although with a bit of a sideways jerk.

Steep turns are easily performed, and thanks to the rudder-aileron interconnect, the ball stays perfectly centred throughout. While power-on stalls occur with a mild break, thanks to the elevator’s restricted up travel, power-off stalls have no break at all and produce just a high sink rate with noticeable buffeting. Positive roll control is maintained throughout slow flight and into stalls.

The stall and spin resistance of Ercoupes are achieved in part by limited upward elevator travel, so it’s important to maintain speed on final in those models. This ensures the elevator has sufficient authority to arrest the rate of descent and properly flare.

‘it is a wonderful little plane’

The 415-G manual calls for an approach speed of 72 mph, and landing is simply a matter of reducing power, levelling off a foot or two above the ground, and allowing the plane to settle onto the runway.

Famed Boeing test pilot Tex Johnston put his pilots into Ercoupes to teach them how to land in a crab so that they would not hit the engine pods of the prototype 707 on the ground using the wing-low crab they had been taught for crosswinds.

The no rudder pedal design means that you must be prepared to fight the tendency to weathervane by turning the wheel away from the wind, contrary to everything you learned in three-control planes. Otherwise, you will join the ranks of the embarrassed who have departed the upwind side of a runway while landing in a crosswind in an Ercoupe. An early flight test report notes that “at first it requires conscious thought, but then something clicks and it seems perfectly normal when in an Ercoupe, but never in any other plane. By the same token, as you turn downwind while taxiing, the upwind wing will often try to rise. The cure, which emotionally seems to make no sense but works perfectly, is to apply a little brake. The wing will drop and you may complete the rollout with a minimum of fuss.”

Cruise speeds vary by engine, but 100 to 105 mph is common. The report notes that an owner upgraded his C-85 engine with an O-200 crank to achieve a relatively brisk 117 mph cruise speed while burning about 5 gallons per hour. Christo Erasmus, the owner of ZS-VCE reports a cruise of around 110 mph on his 115 hp Lycoming.

Today most Ercoupes have been modified with rudder pedals to replicate the controls of a ‘normal’ plane. While this might sound appealing to pilots who prefer traditional controls, owners report that the modification lacks rudder authority and effectiveness.

An original Ercoupe panel – showing the single pedal layout.

Owning an Ercoupe

For such an old design, and an unusual one at that, owning an Ercoupe is surprisingly practical. Provided your Ercoupe’s airframe has no corrosion, it should be an easy plane to own and maintain. Because many were built, parts are plentiful. Univair owns the type certificate and produces new parts, and usedercoupeparts.com is a highly regarded source for used parts.

There are 26 airworthiness directives that apply to Ercoupes of all types, viewable on Univair’s website. Approximately eight are recurring, and these are considered to be relatively simple and easily addressed by an AMO.

Corrosion is the most significant concern and any prospective owner should ensure a mechanic familiar with Ercoupes thoroughly inspects the wing spar with a borescope to

confirm that no corrosion exists. A wealth of information and support is available from the Ercoupe Owners Club.

Conclusion

When considering various aircraft types to buy, most of us tend to take a technical approach. The analytical amongst us collect data, assess performance figures, and guestimate operating costs in an effort to determine which is most suited to our needs. However, the Ercoupe is unique in that some of its most significant strengths aren’t easily quantifiable and don’t show up in spreadsheets. The 1930s-era retro-futuristic look, the relaxed confidence of sure-footed crosswind landings, and the feeling of resting your arm out the window as the scent of freshly cut grass – or highveld smog – comes through the open cockpit on a summer afternoon, make it truly special.

‘The Ercoupe has many amazing features’

For the pilot who values these qualities and has less need for cruising speed, payload and short-field capability, the Ercoupe delivers on the dream of aircraft ownership in spades.

The owners of Ercoupes can be a vociferous lot and prone to aggressive defence of their joy and pride. They will tell you how it was designed, prior to World War II, without rudder pedals, as a spin-proof plane by the genius Fred Weick, who went on to many more successes in aviation — notably the Piper Cherokee line. They will say that it is nearly viceless in handling, can land at any speed from 60 to 110 mph, was the first tricycle-gear plane to be manufactured in quantity, was the first general aviation plane to have a completely cowled engine, and is the source of great fun. Overall it is a wonderful little plane, one to make a knowledgeable pilot happy and an owner proud.

Large wing gives safe slow handling and 100mph cruise speed but needs plenty of runway.

Specifications and Performance

1947 ERCO ERCOUPE 415D
Specifications
EngineCont. C85-12
Displacement188 cu. in.
HP85
PropellerFixed Pitch
Avg. Fuel Burn at 75%17 l/h
Weights and Capacities
Takeoff/Landing Weight1,400 lbs.
Standard Empty Weight855 lbs.
Max. Useful Load545 lbs.
Baggage Capacity65 lbs.
Fuel Capacity24 USG 90 litres
Performance
Vne125 Knots
Max. Structural Cruising Speed99 Knots
Stall Speed CleanUnknown
Stall Speed Landing ConfigurationNot defined
Climb Best Rate560 fpm
Wing Loading9.8 lbs./sq. ft.
Power Loading16.47 lbs./hp
Service Ceiling11,000 ft.

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