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Coupe landings and landing gears

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September 1991 issue of Coupe Capers:

By Ed Burkhead

Here's a transcript of an interview I had with Fred Weick at the 1991 National Convention in Lock Haven.

Question:  "One of the guys said that the Ercoupe was designed so the nose strut should be all the way down..."
Fred's answer: "That's right."

Question:  "And it shouldn't have the snubber cable holding it [the nose gear] up high."
Fred: "It wasn't designed so it 'shouldn't' have a cable.  The cable was never even thought of in the design.  It's other people, later, that have added that at their own whim."

Question: "With the thing all the way down, one gentleman said, it was supposed to touch with all three wheels at the same time."
Fred: "Not at all.  I don't know who said that and that's an absolute untruth.  You can fly it on if you have to but my own preference is to fly it so it touches down very close to minimum speed just as you would a taildragger.  There's no reason in the world why you shouldn't make a nice soft smooth landing at the lowest speed you can get.  On the other hand, it isn't important that you do that. 

"If you land at a higher speed with a taildragger then you have to make an entirely different kind of landing where you make a wheel landing and deliberately hold the tail up until it is slow enough that you can drop it and not fly off again.  Otherwise, if the tail goes down and the higher speed then you're off the ground and flying again.

The Ercoupe, when it's on the ground, rolling along, has the wing at the low angle of attack more like cruising so you'd have to go very fast in order to bounce off again unless you pull back on the wheel and pull it off."

Question: "When the main wheels touch, the nose wheel should be up in the air as much as you can..."
Fred: "I won't say how it should or shouldn't be...every one to his own.  Some people can do it one way and get by with it.  But my own preference, certainly, is to land it very close to minimum speed."

 


Optimum landing technique
by Ed Burkhead

As Fred Weick, designer of the Ercoupe, said, "My own preference is to fly it so it touches down very close to minimum speed just as you would a taildragger.  There's no reason in the world why you shouldn't make a nice soft smooth landing at the lowest speed you can get.".

This is NOT incompatible with complete safety.

Here are the techniques *I* used for reliable landings:

Simply flare into ground effect, hold the airplane off the pavement somewhere between inches and a yard or so and let the speed bleed off, slowly pulling back on the yoke to hold the chosen micro-altitude.

At this micro-altitude, the ground effect on the low wing Coupes is intense and very well dampens gust and turbulence roll.  The plane stabilizes quite well.  Note that if you DO get a wind shear and land suddenly, it is well within the Coupe's design capability - it'll just be less graceful than optimum.

When you reach full back yoke travel, the plane will not stay airborne any longer and will settle to the surface at very near the minimum possible speed.

As an added refinement, when the runway is long enough, set power at about 200 rpm above idle as you flare.  Start by setting the nose on the landing lights at the far end of the runway and hold it there.  This small amount of power and moderate flare angle does two things:
1.  It puts some slipstream over the elevator, letting you get a little bit slower (does not apply to split elevator Coupes).
2. It reduces sink rate virtually guaranteeing a squeak-squeak landing every time (assuming you were flying level within about 1-6 feet of the surface.

(Note:  if you do not have the under-the-leading-edge indentation/concavity I would NOT recommend this technique.  I don't know anything about the stall/imminent-stall behavior of an airfoil without the low-speed leading edge cuff - for all I know, it might pitch you nose down or nose up or something undesirable.  Based on reports, I think there's a good chance it might just suddenly drop you.  But I'd also recommend you get that deficiency fixed quickly for legality and, especially, safety.)

As you develop skill with this technique, you'll find an airspeed to use on final (as referenced on your ASI) that will give you a good, reliable flare without having excessive float.  I'd suggest starting with flying final at 1.4 times minimum flying speed as measured by your ASI.  With experience, you might work it down to flying final at 1.3 times minimum flying speed.

As a refinement, I got to the point where I'd fly the pattern at 1500 rpm until the particular spot on final when I knew I had the runway made.  At that point, I'd pull power to idle.  An engine failure at idle is, shall we say, pretty safe when you already have the runway made.  Just as I flared, I'd add just enough power that I could hear the change in RPM and that was just about right for the 200 RPM increase mentioned above.  Squeaker landings were virtually guaranteed.

If I get a chance to be pilot-in-command of a Coupe in the future, I think I'll work on doing the entire pattern at 1200 rpm.  This would give a steeper approach and make it more nearly guaranteed that you could make the runway in spite of a power failure anywhere in the pattern.  With my 1500 rpm approach, a power failure right before the turn to base was a bit iffy for making it to the runway.  I think this approach might require more precision on adjusting pattern turns to handle current wind and distance from the runway conditions.

Flying a Coupe to a perfect landing, without flaps or ability to slip, IMHO requires more skill than doing the same in aircraft with the flap/slip "crutches."   Never be ashamed of the skill required to fly your Coupe perfectly.

Those are just MY techniques and thoughts.  Develop your own!  Being a test pilot to develop optimum techniques is a fun thing to do in your aircraft!

JMHO

 

Bob Sanders crosswind landing technique update
From Coupe Capers, December 1991

[EDITOR’S NOTE:  Bob Sanders is an aeronautical engineer who worked with Fred Weick, doing research at the NACA in the 1930s. Saunders was one of the group who worked with Fred to develop the W-1.  When the Ercoupe was being designed at ERCO, Bob was the prmary test pilot.  His knowledge of Ercoupe flying characteristics may very well match Fred’s.

The following letter was written by Bob during the time that Saunders Aviation was the distributor for Ercoupes.

{Be aware the the working speeds of the aircraft talked about in Bob’s letter apply to the early model Coupes with an almost new airspeed indicator.  Do not just go out and do landings using these airspeeds.  When you read the approach speed numbers, remember that he’s figuring the minimum flying speed of the aircraft is about 50 mph.}

 Ercoupe model “D” owners, be sure to read the editor’s note at the end of the article.

 

By Robert Sanders
Sanders Aviation, Inc.
World-Wide Distributors for Ercoupe
June 30, 1948

IMPROPER LANDING FROM POOR INSTRUCTION

Word continues to reach us of many improper landings being made throughout the country in the Ercoupe.  We can only conclude that improper instruction is the cause of these landings and the resultant high maintenance costs that ensue.  The Ercoupe is a safe and simple airplane to fly; no difficulties with landings should be encountered if a few simple and easy rules are taught and observed.  Proper landing instructions will go a long way toward reducing accidents, the cost and inconvenience they involve, and toward improving Ercoupe’s already excellent reputation in the flying world.  With this idea in mind, let us examine some of the errors most generally made and see what we can do to improve landing technique.

HOW FAST?

The major error most prevalent in landing the Ercoupe is too much air speed on final approach.  For the student and less experienced pilot, 70 m.p.h. on final approach is ample.  At this speed, full control is maintained and the rate of descent is gradual.  For the experienced pilot, a 65 m.p.h. approach is plenty fast and more than adequate to ensure full response of all controls. (though the angle of descent is somewhat higher than at greater “flare-off”).  Let’s give this a try.  SLOW THOSE APPROACHES DOWN to a reasonable speed.  On a calm day or with a light breeze, the speed in approach can be dropped another 5 m.p.h. to advantage.

KEEP YOUR NOSE UP

It further appears that some pilots are under the impression that the Ercoupe nose gear should be used like a battering ram.  Obviously an error.  The Ercoupe should be landed in a nose-up attitude.  Excellent results can be obtained from a “full-stall” landing.  Landings of this type will insure that the landing is made on the main gear.  After initial contact has been made, let the nose come down and then apply brakes if needed.  Don’t land nose wheel first; it won’t work for long.  Don’t shove the wheel forward.  Let slide gradually to neutral slowly.

When making cross-wind landings, land in a “crab” attitude ON THE MAIN GEAR.  Be sure it is a minimum speed landing.  Again, lower the nose; do not shove it down.  The airplane will take care of itself.  Do not try to turn down the runway as you land.  Just keep the wings level and hold wheel loosely until the ship is well on the ground.  A generous application of brakes will right wings if one starts to raise – the result of a fast landing.  The slow cross-wind landing is one of the hardest features to sell to pilots.  Once it has been properly demonstrated, however, the ease of the landing will convince even the most hardened skeptic.  Give it a try.  Let the airplane do the work.  But do it at a slow speed.

If, by chance, you come in too high and slow, use a little throttle.  Do not shove wheel forward to pick up speed at less than 50 feet altitude.  It takes a little altitude to get the nose back up.  This applies equally well on a bounce. 

HOW ABOUT TAKEOFFS?

Now a word on take-off.  The shortest possible take-off from a hard, smooth field is made with the wheel neutral – run until 45 m.p.h. is reached when the wheel is snapped back to clear the ground.  Then the wheel is eased forward to maintain a few feet of altitude while picking up at least 60 m.p.h. air speed for climb.  This is not a smooth take-off and is not recommended for normal use.  It is good to know for limited runway and is the same technique as the cross-wind take-off except that 50 m.p.h. should be used in cross-wind takeoffs.  Do not hold wheel forward of neutral on cross-wind take-off; pull off the ground when the airplane feels too light to stay down.

For normal take-off, hold wheel well back of neutral – except on soft or rough fields hold full back – and let ship pick up speed.  It will take-off normally at a safe speed and climb should then be made at 65 m.p.h. for best rate (60 m.p.h. for best angle) of climb.

TREAT THE LANDING GEAR RIGHT

On rough fields, except strong cross-winds or tail winds, keep the airplane weight off the nose gear as much as possible by holding the wheel back, during taxiing as well as take-off runs.  To save the nose gear and brakes, apply the brakes gently and then only after the nose wheel is on the ground.  Reserve sudden application of the brakes for extreme conditions.

In the Ercoupe, you will have an extremely reliable and rugged landing gear.  Like any other mechanism, however, it will give trouble under abuse or misuse.  Treat it right, and it will take care of you.  Check your gear after unusually hard treatment.

To get maximum use and long-life from your landing gear and to reduce accidents and maintenance costs, let’s practice and preach the following simple rules:

1.      Reduce approach speeds to 70 m.p.h. or less.

2.      Land on main gear and lower nose gently.

3.      Cross-wind landings are simple – land crabbed (and slowly) on the main gear, lower the nose gear.  The Ercoupe will do the rest.

4.      Keep the weight off the nose wheel when possible.

5.      Check, lubricate, and fill landing gear regularly.  Check particularly after unusually rough treatment. 

Yours for more and softer Ercoupe landings,

Cordially

(signed) Bob Sanders

 

[A copy of this series of article was sent to Bob and he added some comments. Ed.]

By Bob Sanders

November 21, 1991

I could add that the effect of applying the brake in the Ercoupe, when one wing is raised, is three-fold.  First and foremost, only one wheel is touching the ground and, therefore, the high wing is carried forward by inertia which tends to flatten the wings as well as reduce the angle of attack.  The other effect is slowing the airplane down, thereby reducing the lift on the wing.

In your first article [Ron Kerlin’s Currency Corner], you speak about the angle of the elevator being limited without indicating how to check the angle.  The factory drilled a small hole in the trailing edge of each rudder to indicate the proper angle.  When the elevators are held to the stop by use of the wheel only, the trailing edges of the elevator should be aligned with these holes.  Of course, after so many years, the rudders may have been changed and the current ones may not be properly drilled.  [ For more measurement techniques and elevator up-travel details for each model, see the Pre-Purchase Inspection article at http://edburkhead.com/Ercoupe/index.htm ]

The problem with the limited elevator in the Model D was recognized by Sanders Aviation Co., who developed the split elevator to assure the adequate elevator control under all conditions without permitting too high a nose attitude power-on , which could result in conditions that might permit a spin.

I had an experience while flying around the country to the distributors in order to demonstrate the use of the brake as explained above.

I was landing at the main airport in Provo, Utah, with the wind coming off the Great Salt Lake at about 35 MPH.  There was nothing to break the wind, not even a fence between me and the water and I was landing parallel to the shore line with a 90 degree crosswind.

I made two landings in which I had to step hard on the brake immediately after touchdown as the runway grabbed the tires, making skidding almost zero.  The pilots I demonstrated to were convinced, as was I, that the brake application prevented a damaged wing tip.  That was the most extreme crosswind I ever experience as, usually, the wind is reduced when you are 10 feet above the runway because of trees, houses and vehicles, but not at Provo!

 

By Ed Burkhead

1991

Model “D” owners, please read this.

In the model “D,” the elevator is limited more than for any other model of Ercoupe.  This affects the working speeds of the airplane.

Some speeds stay the same.  Best rate of climb, best angle of climb, maximum structural cruise, maneuvering, and velocity never exceed speeds don’t change because of the extra limitation of the elevator.

However, the minimum flying speed is affected!  In my model “D,” the minimum flying speed, power off, is about 65 mph by my [later determined to be in error, very old] airspeed indicator.

If I were to fly the approach at the 65 mph that Bob recommends, I wouldn’t have any more elevator to use for a flare!

I strongly recommend that each of you test your own airplane to find out exactly the power off minimum flying speed.  In any new-to-me Ercoupe, I fly the approach at minimum flying speed plus 15 mph – using that as a starting point.

Owners of other models of the Ercoupe/Aircoupe should also test their plane’s working speeds because the airplane’s trim or airspeed indicator may have changed over the decades.

Our thanks to Ros L. Hawks, Durango, Colo., who first brought Bob Sanders’ original letter to my attention and to Burt Ellegaard, Shakopee, Minn., who sent me a copy of the letter.  This gave me the opportunity to go to the source fo the updated material above.