Ercoupe/Cadet

These classic two-placers are affordable, stall/spin-resistant and impressively capable in crosswinds.

Tom Murrell Flying his Ercoupe

Back in the day—as in 1939—the Ercoupe was designed to be exceptionally safe by making it resistant to stalls and spins. But the airplane racked up a number of firsts, including being the first successful production GA airplane that had a nosewheel, plus a fully cowled engine. This contributed to more speed than most of its counterparts had. Better yet, an Ercoupe can handle a crosswind of twice the velocity that can be dealt with by almost any other airplane.

These days, by nature of its design, the Ercoupe/Aircoupe doesn’t come across as having an abundance of testosterone, so what may be the funkiest two-place airplane from the 1940s is a bit of a sleeper on the used market. We think it’s overlooked by potential buyers who don’t understand its capabilities. Owners seem to love their Ercoupes for a variety of reasons.

Moreover, the venerable ‘coupe remains one of the cheapest ways to get in the air. A nicely kept up early Ercoupe retails for around $14,000, although a pristine restored model may sell for much more. Some can be had for as low as $10,000, but prospective buyers should watch out for basket cases in that price range.

Surprisingly, 20-year-newer (1968-1970) Mooney Cadets—Ercoupes with a single tail and rudder pedals—might also sell for under $20,000.

The C model, the only model that has a low enough gross weight to qualify under Light Sport, is quietly becoming an in-demand airplane. Its referenced value in the Aircraft Bluebook may be behind the times.

If you find a decent Ercoupe, you get a fun airplane suitable for Saturday afternoon joyrides on nice days or modest cross-country trips. You can fly along with the canopy open, your elbow out in the breeze, and pass the folks in their two-place Pipers and Aeroncas. Those cost more and have the engine cylinders dragging along in the breeze.

Model History

First of all, is it Aircoupe or Ercoupe or Cadet? It depends on who you talk to and really the year of manufacture. The airplane has a long, complex history with on-again, off-again production dating back prior to World War II and then the brief, but intense, postwar boom.

The first model appeared in 1939, and was manufactured by the Engineering Research Corp. (ERCO), which was the source of the “ER” in Ercoupe. It was designed by Fred Weick, very much an aeronautical genius, who went on to design the first truly crashworthy ag-plane, which became the Piper Pawnee, and to collaborate on the design of the Piper Cherokee line. As a National Advisory Committee for Aeronautics (predecessor of NASA) engineer, Weick had designed the Weick W-1 in response to a call for an airplane that could not be stalled.

Ercoupe full panel

Back then, the W-1’s design was a very big deal because stalls were even worse killers than they are today. They weren’t well understood, and the small engines available for GA meant shaky performance and a relatively small envelope between cruise and stall speeds.

Weick went to work for ERCO and used many of the techniques he’d developed with the high-wing W-1, including limiting up-elevator travel for stall resistance, for the low-wing Ercoupe.

Production continued on the original Ercoupe through 1941, when the attack on Pearl Harbor brought all U.S. civil aircraft manufacturing to a standstill. Some 112 were built before the war.

Postwar, ERCO got in high gear and pumped out more than 4000 75-HP ‘coupes in 1946, an impressive volume second only to Mr. Piper’s Cub. These models are known as the 415-C and they have a four-cylinder Continental C-75-12. (Many have been converted to C-85-12 engines.)

The Model C and CD, with a 1260-pound gross weight, are the only Ercoupes that qualify for Light Sport.

Production of the 415-C, D, E and G models continued until 1950. Model changes in the C and D were minimal, but the D model got a weight increase to 1400 pounds by further limiting up-elevator travel. The C and D had 75-HP engines while the E and G had 85-HP powerplants. The E and G models also had split elevators.

The postwar boom evaporated by 1947, hitting the two-place market hard. ERCO soldiered on until 1950, eventually building about 5000 airplanes. It then sold the Ercoupe type certificates to Univair. Univair didn’t build any complete airplanes, but did support the line with new parts.

In 1958, a company called Forney took over production rights and introduced a spruced-up model called the Fornair F-1 Aircoupe. The F-1 ‘coupe had a 90-HP Continental C-90-12F, but otherwise retained most of the design features that ERCO had developed. Forney built a couple hundred airframes before retiring production.

Rights to the airplane were eventually purchased by Alon Inc., which built 245 airplanes between 1962 and 1967. Alons have a bubble canopy rather than the sliding windows found in the earlier models.

Surprisingly, the line was then sold to Mooney—yes, Mooney—which made major modifications to the airframe, including a single tail in place of the original’s Lockheed-like twin-fin design, and retained the rudder pedals, which Alon had added when it took over the design. (You can add pedals to any Ercoupe via a kit sold through Univair—www.univair.com—for about $1400.)

Ercoupe Panel 3

Mooney had in mind a basic trainer and called the revised model the Cadet. But it wasn’t much of a seller. Only 118 airplanes were made between 1967 and 1970.

By 1973, rights were sold back to Univair, the same company that had bought the design from ERCO. As before—and still—Univair supported the airplane with new parts production. All told, nearly 5800 ‘coupes were built, with the last one coming out of the Mooney plant in 1970. For all practical purposes, however, the majority of Ercoupes were built between 1945 and 1952.

Notable Design

At a time when most civil aircraft were covered in fabric stretched over welded tubular frames, the ‘coupe was an all-metal, riveted design but with fabric-covered wings on early models, later changed to all metal.

The Ercoupe had a pair of vertical fins on a single tail boom, a design that had become popular with Lockheed and Beech twins in the 1930s. And although the Ercoupe had rudders, it had no rudder pedals. The cockpit floor has but one pedal, for the brakes, helping with legroom for tall pilots. The twin tails put the rudders outside the twisting propwash, designing out some, but not all, of the left-turning tendency in a climb. The airplane still needs right wheel during a climb.

Weick set out to confront two safety issues of the day: stall/spins and groundloops. That meant the Ercoupe was one of the first civil aircraft to take advantage of what was being learned about the stability of a nosewheel versus a tailwheel for control on takeoff and landing. It took the rest of the industry another decade to adopt this visionary idea.

Further, the Ercoupe had a collar on the control column that limited elevator up travel—if you can’t reach the critical angle of attack, you can’t stall the airplane. And if you can’t cross control—remember, no rudder pedals—you can’t spin it, either. The airplane has rudder control, but it is automatically coordinated with the ailerons through a mechanical linkage (only the rudder on the inside of a turn deflects).

The no-stall, no-spin philosophy drove the design entirely. The restricted elevator travel required a nearly constant CG so the Ercoupe had side-by-side seating. The lack of rudder controls presented a theoretical problem on crosswind landings, so Weick’s solution was a rugged trailing-beam gear design that allowed the airplane to be plunked down in crosswinds, without the usual side-slip correction.

Owners say the gear is more than beefy enough to stand the load of landing in a crab, and control authority is sufficient to keep the airplane tracking correctly once it’s on the pavement. You can do a bad landing in an Ercoupe, but it takes effort to damage the gear.

It’s not, as some think, a castering crosswind gear as in some versions of the Cessna 190/195. After a crabbed touchdown, the airplane immediately turns to point in the direction it is traveling, so you feel the sideload on touchdown. You then steer the airplane with the control wheel during rollout, turning slightly away from the wind to counteract the tendency of the airplane to weathervane.

Rudder purists sneered, but the Ercoupe was successfully tested in crosswinds up to 40 MPH—far beyond the capability of almost any aircraft, then or now. True, it took nerve to drive the thing on in a stiff crosswind, but the gear proved up to the task. With the landing gear properly adjusted and the top of the tails 75 inches above the ground, the wing sits at a zero-degree angle of attack when the airplane is on the ground. This allows landings to be performed at speeds up to an incredible 110 MPH, although owners we spoke with were not willing to try such a speed.

When Boeing came along with its Dash 80, the 707/717/KC-135 prototype, it used the lowly Ercoupe to train pilots to land the new airplane. Because of its low-slung engine pods, the new jetliner couldn’t be slipped to a landing. Pilots had to learn to land it in a crab and ride out the rudder-induced correction.

And, in fact, the initial design was good enough not to require much meaningful fiddling. Rudder pedals were made available as an option in 1949, mostly as a psychological crutch to entice pilots who thought a “real” airplane had to have pedals.

In most Ercoupe models, fuel capacity is 24 gallons, in two 9-nine-gallon wing tanks and a 6-gallon header tank between the panel and the engine. An engine-driven pump sends fuel from the wing tanks to the header tank, from where it gravity feeds to the carburetor.

There is a float with a wire sticking out of the header tank. Once it starts down, either because all of the fuel in the wing tanks is depleted or the engine-driven fuel pump has failed, you have about an hour before it gets quiet up front. As with some Cessnas, there’s no fuel tank selection, just a simple on/off switch located on the cockpit sidewall.

Open canopy back

Photo by B. Easly.

From a crashworthiness standpoint, the fuel system design is grim. The wing fuel tanks are in front of the spar, unprotected on impact. The header tank, as with too many of the Ercoupe’s contemporaries, is between the occupants and the engine.

The airplane developed somewhat of a “not a real” image for its lack of rudder pedals. The ‘coupe was too easy to fly, suggesting that anyone who would own one didn’t have the right stuff at a time when the phrase hadn’t even been coined yet. This is an absurd state of affairs, of course, and one that seems to dog every radical safety idea, from seat belts up to and including ballistic parachutes.

After a series of minor engineering changes, the Forney airplanes got all-metal wings. To this day, there are debates as to whether this was an improvement. Alon added a sliding canopy, replacing the earlier slide-up/down windows.

Full-opening cowling halves

Reverting to high-testosterone thinking, Mooney, calling it the M-10 Cadet, revamped the Ercoupe’s image by installing a single tail—complete with the trademark “backward” vertical leading edge and angled trailing edge. The Cadet also had standard rudder pedals, with enough elevator authority to actually stall briskly and even stall strips, so the airplane would stall like a “real airplane.”

Performance

With its twin tails and somewhat sleek design, the Ercoupe looks fast to some eyes, and it does OK. Despite having a fat, low-aspect ratio wing that’s excellent for slow speed and stall characteristics but middling for climb and cruise, a 90-HP Ercoupe will run with a Cessna 150 or Luscombe.

A 75-HP ‘coupe will struggle climbing above 4000 feet on a warm day with two people aboard; solo, it’s not bad. One owner said his 85-HP model with a climb prop “loves the ground.” He noted that if you put two people and some baggage aboard, you know you’re really carrying a major load. “They claim 500 FPM for the first five minutes, but mine never does that well.”

An Ercoupe is not a short-field machine—it also uses much more runway departing than it does landing. The twin tail design did not eliminate all left-turning tendency—P-factor is still there—so allowing the speed to get much below 75 MPH in a climb means there will be so much drag from aileron and rudder deflection that the climb rate can be frighteningly low when trying to clear an obstacle.

Ercoupe crash site

Like other airplanes of the day, such as the J-3 Cub and Champion, the Ercoupe is not an all-purpose machine, performance wise. The 75-HP models will be zippy enough for solo flying but if you want to do much two-person flying, try to find a 90-HP Alon model or, at the least, an 85-HP version with a climb prop.

Then again, among the postwar designs, Ercoupes hold their own, and then some. Plan on around 100 MPH in 75- and 85-HP models and perhaps 110 MPH in the 90-HP models.

By comparison, you’d be lucky to see 80 MPH in an early Cub, and even late-model Cessna 150s struggle to make 110 MPH.

A ‘coupe really will handle strong crosswinds. Owners reported landing in direct crosswinds of more than 30 MPH. Folks at the Ercoupe Owners Club confirmed the ability of the airplanes to land in very strong crosswinds, but noted that one place where Ercoupe pilots do get into trouble is attempting to take off in very strong crosswinds.

Flying Qualities

So what’s it like to fly an airplane with no rudder pedals, a canopy/windows you can open in flight and systems straight out of the 1940s? Different, to say the least. Then again, that’s what attracts owners to the Ercoupe in the first place.

It’s never going to be accused of being your average spam can. Generally, the ‘coupe is a good flyer with appealing handling characteristics. It has full-span ailerons—no flaps—so roll response is far snappier than other airplanes of the same era. Properly rigged, it will not stall—the up-elevator restriction means the airplane has a “minimum speed” in 1 G flight. It won’t go any slower—power off, it simply descends under full control.

1946 Ercoupe

The downside is that the sink rate can become eye-watering. Our accident survey found several ‘coupe accidents on landing were due to the pilot failing to arrest a high sink rate after getting slow. This was consistent with comments to us that besides trying to take off in a stiff crosswind, the second area where Ercoupe pilots get into trouble is with allowing a high sink rate to develop.

Also, in a steep turn, you may reach full aft wheel and full power but be unable to maintain altitude—potentially developing a stunning rate of descent. The only way to stop the sink is to roll out of the turn. It may be necessary to fly level to accelerate to a speed at which the airplane will begin to climb.

The rapid rate of descent allows for precise and impressive short-field landings but if you’re not careful, the same trait can and will put you in the weeds short of the approach end of the runway.

Once a ‘coupe has been slowed to its minimum speed on final, it will not flare without adding a lot of power because the yoke is already fully aft. In reality, an Ercoupe is quite easy to land. The trailing beam gear is forgiving, usually soaking up the too-high arrival rate of a ham-fisted pilot. In a bouncy crosswind, just crab the airplane into the wind and touch down as you would with no crosswind.

The airplane will reliably right itself on the runway and the rest is easy, although you do have to steer away from the crosswind—counterintuitive for aileron positioning for pilots who fly three-control airplanes.

Luddites who insist on having rudder pedals can find a model so equipped, but one owner of a pedal-equipped Ercoupe says he crabs it onto the runway anyway.

Another owner who contacted us thinks the rudder pedal mod is actually dangerous because it’s not connected to the nosewheel and may confuse pilots about ground handling. On the ground, you drive the Ercoupe like a car, steering with the control yoke, not the pedals.

Maintenance, Parts

Chuck Rosenfeld and Maynard Smith

A top concern for anyone buying a nearly 70-year-old airplane is parts availability. Fortunately, any model that was built in the thousands—as the Ercoupe was—is usually still around in sufficient quantity to represent a profitable market for parts makers. For Ercoupe owners, the best source of parts continues to be Univair (www.univair.com), which holds the type certificate for the airplane and makes most structural parts.

Another company, Skyport Services (www.ercoupeparts.com), specializes in Ercoupe parts, STCs and accessories and is a cornucopia of ‘coupe-iana, including an STC for gross weight increase.

Owners highly recommended the Ercoupe Owners Club (www.ercoupe.org), said it is passionate about the care and feeding of the marque and has a good website and newsletter for all thing ‘coupe.

As with any older aircraft, the largest area of concern with an Ercoupe is corrosion. There have been two ADs calling for inspection for corrosion in the wings, AD 2002-26-02 and AD 2003-21-01. Buy the wrong airframe and you could face potentially uneconomic repair costs. Since many Ercoupes have and continue to live outdoors, water incursion is a worry.

Water tends to leak into the fuselage and corrode the belly skins. The tail cone and wing spar lower caps are also corrosion-prone areas. Mice can also be destructive.

It should go without saying that on a prebuy, the inspecting mechanic should check the airplane carefully for corrosion. The Ercoupe Owners Club website has a good pre-purchase examination checklist.

Another common problem in the Ercoupe is the nosewheel, especially the single-fork models on the earlier airplanes. Decades of landings and abuse and side loading due to crabbed landings in crosswinds will take a toll. Shimmy can be a problem due to loose or worn nosewheel linkages.

Mooney M-10 Cadet

Look for the double-fork nosewheel and check the linkage. Some Ercoupes have been converted from the single fork design. If that hasn’t been done, it may be worth considering, although some owners say the single fork is fine.

Main gear struts can also be a problem, again due to years of pounding. The shock struts can seize up if they’re too low on fluid, and landing forces are transmitted directly to the wing spar center section. Check it for damage and look for a reinforcement gusset that has been retrofitted to many airplanes.

Check for unrepaired damage. One accident was triggered by wingtip damage that had simply been Bondoed over. As older airplanes go, the Ercoupe isn’t overburdened with a huge number of ADs but one to check for is AD 59-05-04, which calls for beefing up the rear spar where the outer wing panel attaches. Noncompliance with this AD can be a killer.

There are a number of mods for the series; the 100-HP Continental O-200 engine upgrade is popular.

Ercoupe Errors: Maintenance

Tom Murrell Flying his Ercoupe

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The Ercoupe series of airplanes evolved from a design competition to create the safest possible airplane—one that was incapable of stalling—and that was as easy to fly as possible. It met those design criteria. When elevator travel is properly adjusted and the airplane is within CG limits, it cannot be stalled, and the two-control version is extraordinarily easy to fly (and, in our opinion, a lot of fun).

There is no free lunch in aviation. While an Ercoupe cannot be stalled, it can establish a heroic rate of sink when the yoke is full aft (generating about 60 MPH). That means a risk of hard landings or hitting obstructions short of the runway. The two-control arrangement means that when climbing at a speed below 75 MPH, the degree of aileron deflection to overcome P-factor generates so much drag that the rate of climb may simply disappear—creating an increased risk of hitting obstructions on takeoff for pilots who are casual about speed control.

Finally, we’ve informally observed over the years that airplanes that are easy to fly or designed to be “safe” have a certain attraction for pilots who will let their skill level diminish to the point that they rely on the design of the airplane to protect them from themselves—not necessarily a wise idea.

Our review of the 100 most recent Ercoupe accidents confirmed our concerns regarding the trade-off for safety versus controllability although, surprisingly, there were seven loss of control (LOC) inflight events, only one of which appeared to be a stall. The remaining six involved very high sink rates, in some cases shortly after takeoff. Even though there were seven accidents involving hitting obstructions on landing and 11 hard landings, there were only a total of 29 landing-related accidents, a number that we considerer better than average. There were only five runway loss of control (RLOC) events—an usually low number. Flown on speed, an Ercoupe is amazingly easy to land and take off, even in strong crosswinds.

A major concern was an apparent willingness of Ercoupe owners to forgo or skimp on maintenance. Twenty-six accidents were due to engine maintenance issues, several involving the failure of parts that were still on the engine 50 years after the airplane rolled out of the factory. It may be a safe airplane, but stuff does wear out. On top of that, there were seven fuel contamination accidents—in all cases the contamination included foreign material such as rust in addition to water.

The fuel system requires attention because fuel valves have to be on and a fuel pump working to transfer fuel from the wing tanks to the fuselage header tank. Once the cork float fuel gauge starts going down on the header tank you’re either out of fuel in the wing tanks or the fuel isn’t transferring. Six pilots didn’t figure that out and things got quiet while there was fuel in the wing tanks.

Two pilots decided to do aerobatics in their Ercoupes and pulled them apart inflight. Seven pilots hit obstructions after takeoff, one after an intersection takeoff—an Ercoupe is not a short-field machine.

A father and son with zero flight experience were given permission by the owner—hey, it’s easy to fly—to fly his Ercoupe. They got 250 feet up before losing control and diving into the ground.

Realistic Expectations

Tom Murrell Flying his Ercoupe

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Owners tell us the Ercoupe is what it is: a fun, easy-to-fly airplane with few bad habits that’s a good choice for a starter airplane.

On the other hand, a prospective buyer shouldn’t go into the deal looking for a steal.

Of all the Ercoupe models to choose from, we think the later Alon and Forney models may be the better values, even if they cost a little more.

The early airplanes had fabric wings—a plus for inspections—but the later models with metal wings have been equipped with inspection panels, so hidden corrosion is less of a worry. It can be found, if you look.

Last, don’t expect too much of an Ercoupe. If you have places to be and things to do and serious cross-country is on your list of desires, the Ercoupe is not a good choice. But it’s an eminently affordable and maintainable weekend fun flyer with a certain 1940s classic panache.

Owner Comments

I have owned three 415-C Ercoupes. They have been efficient, docile and quite low-cost to fly and maintain. The parts availability is outstanding for a classic.

Due to a maintenance error, I was forced to make a deadstick landing in badlands after the prop came off in cruise flight. The all-aluminum structure was exceptionally energy-absorbing, and although the aircraft was destroyed, I walked away without injury.

Chuck Rosenfeld, Region 3 Director
Ercoupe Owners Club

I have flown and greatly enjoyed my 1959 Forney F-1 Aircoupe over the last three years. Flying open cockpit as a couple is a new flying experience for us and we have been amazed by the attention the aircraft gets everywhere we go. It has been more than once that we have been greeted at fly-ins with a tongue-in-cheek remark, “Have you ordered your rudder pedals yet?” and I usually respond: “No, those are for beginners!” It just never gets old.

Our favorite destination is the annual Triple-Tree fly-in and as it turns out the Aircoupe makes for a better camping plane than expected. The baggage compartment is sufficient for lightweight camping gear for two and a martini shaker for our favorite after-flight drink. Hence the name “Martini Girl.”

Patrick Oltmanns
Charlotte, North Carolina

My Ercoupe interest began with a 1943 Popular Mechanics article. Eventually, one came up for sale at my local field—I sold my share in a Cherokee and became an Ercoupe owner. I don’t understand how some people can sneer at ‘coupes because they are, to me, really flying. The Cherokee was somehow all closed in and insulated, like an old station wagon. Much of the year I fly the Ercoupe with the top down; it’s wonderful.

Even repowered with a C-85 (which is an improvement over the C-75), it burns below 4 GPH a lot of the time. As for speed, it will exceed 114 MPH. Plus, people like to come up and talk about the airplane.

It’s an honest and straightforward airplane to fly—a reasonable crosswind is no problem at all. It is a trifle chilly in January. I have no plans to “move up”—I’m there.

Parts and repair? Skyport has good, helpful people. Best may be the Ercoupe Owners Club. It has online offerings about what to look for and questions to ask. When learning the ins and outs of my airplane, online conversations eased the way and brought me into the community.

Fred Weick’s work of all those years ago certainly bore some wonderful fruit. For me, the Ercoupe is the most fun flying I’ve had.

Steve McNew
via email

Once the pilot understands the peculiarities of the plane, about the only thing he or she can’t do in it are slip and spin. I’ve landed my Ercoupe in a 28-knot direct crosswind with no problem. At a fly-in, I watched four Ercoupes and a Grumman Tiger land in a gusty crosswind—only the Tiger had to go around.

Obviously, both takeoffs and landings in a crosswind are handled differently from a three-control airplane. Also, on the ground, the wing has no angle of attack and will not fly at any speed until the nose is raised. This allows the airplane to gain flying speed with the nosewheel safely on the ground. Then the airplane can be popped into the air and a turn made into the wind to set up the appropriate crab for climbout.

Crosswind landings are made crabbed; the trailing link gear will swing the nose forward as soon as the main gear are on the ground.

There are a number of mods for the Ercoupe; four that come to mind are: enlarged baggage compartment, alternator conversion, master relay at the battery (providing more safety for the electrical system) and Cleveland wheels and brakes.

Larry Snyder
via email