Re: [COUPERS-FLYIN]

[Sydney Cohen]

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Doctor Beeman,  
    No, no, no.  You've got it all wrong.  If you try to land a tailwheel airplane in a crosswind without kicking it straight, the tail will come around and try to pass the nose.  Why?  Because the main gear is ahead of the center of gravity of the airplane.  On the other hand, a tricycle gear airplane has the main gear behind the center of gravity, which makes the airplane straighten itself out. 
    Imagine that you are landing your Ercoupe in a crosswind.  We'll do it in slow motion, like the guy in the Mercedes commercials.  You line up the airplane above the runway centerline on final approach and you keep it there with tiny correcting movements of your yoke, but you keep the wings as level as possible.  You hold the nosewheel off the ground in the flair.  The main wheels begin to touch and start scraping the runway.  The nose is pointed (let's say) 30 degrees off to the right due to the crosswind, but the airplane is traveling down the runway centerline.  The most concentrated mass in the airplane is the engine and you, both located AHEAD of the main wheels which are now scraping the ground.  Physics pulls the nose of the airplane around, so the engine and you and the rest of the airplane are now pointing in the direction of travel.  Newton said that a mass that is going in one direction tends to continue in that direction unless acted on by an outside force.  This is the "magic" force that you are asking about.  You can do this technique in any tricycle gear airplane, but if it's not an Ercoupe, it isn't engineered for the side loads encountered.

Syd


[EMAIL PROTECTED] wrote:

If you land an Ercoupe on the mains in a crosswind and wait "...until the coupe itself swivels straight down the runway..." please tell me specifically what force will cause the aircraft to "swivel straight down the runway"?

The answer is there is no magical force available to an Ercoupe or a spam can for that matter. A spam can uses rudder to counteract the crab just before touchdown, but a rudderless Ercoupe must use the runway itself to counteract the crab, for if the Ercoupe pilot tries to take out the crab before touching down, he'll simply fly away from the centerline.

The only counterforce to a crosswind crab that a rudderless model of the Ercoupe possesses is the force exerted through the nose wheel touching and counteracting the cocked main gear. This is what the POH calls for and this is all there is. There is no automatic swivel straight down the runway and if you wait for it before planting your nose wheel you'll be cutting daisies.

Dr. R. Beeman

 

-----Original Message-----
From: Ed Burkhead
Sent: Oct 15, 2006 10:58 PM
To: Cflyin
Subject: RE: [COUPERS-FLYIN]

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Good comments, yourself, Harry.

 

I’ll take mild exception to this paragraph Harry wrote:

> To successfully land a coupe you must keep the nose

> wheel off the ground until the coupe itself swivvles straight

> down the runway, THEN LOWER THE NOSE, AND LOSE

> LIFT......RESULTING IN LITTLE IF ANY SIDE STRESSES

> ON THE NOSE GEAR AND ENGINE MOUNT ( NOSE

> GEAR IS ATTACHED TO ENGINE MOUNT).

 

I would revise it to say:

For an ideal landing in a Coupe, you must keep the nose

wheel off the ground until the Coupe itself swivels straight

down the runway, THEN LOWER THE NOSE, AND LOSE

LIFT......RESULTING IN LITTLE IF ANY SIDE STRESSES

ON THE NOSE GEAR AND ENGINE MOUNT ( NOSE

GEAR IS ATTACHED TO ENGINE MOUNT).

 

 

We all know of gobs of successful Coupe landings in which the nose gear DID touch before the aircraft turned to line up with the direction of travel.

 

A minor quibble.  Harry’s right about his described landing being the right way to do things, if you can.

 

Ed Burkhead

http://edburkhead.com

ed -at- edburkhead???.com          (change -at- to @ and remove "???")

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