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Greg has made many good points. Please let me make some agreements and disagreements. Greg said: > Technically, you are both right. The gear itself does not caster. The WHOLE > AIRPLANE casters as a result of the drag-link on the main gear. The "drag-link" on the main gear has NOTHING to do with the airplane turning to align with the direction of motion. It is the simple fact that the main gears are behind the center of mass and that they're fixed laterally. The main gears experience side-load force as long as they're not in alignment with the direction of motion and this causes them to drag back to come into alignment with the direction of motion. The nose gear does NOT provide similar side load force except for an instant before it swivels. Hold the wheel lightly (or take your feet off the rudder pedals) when the wheels touch so the nose wheel CAN swivel. Since the nose wheel is NOT providing side load force and the main wheels ARE, the airplane rotates. Please do not call this turning of the airplane "castoring" since that greatly confuses the issue - it makes people think of a castoring wheel like on an office chair and Coupes DON'T have such wheels. (Just a semantic difference, I know, but I think it avoids confusion.) Greg said: > Understanding the process helps you understand the crosswind technique > as recommended in the book. Take off smartly, to minimize the 'argument' > between the ground and the air, but land gently and keep the nose gear off > to give the mains time to 'negotiate' direction of travel with the ground while > the flying surfaces become more and more ineffective and of course try to > ensure that the nose wheel doesn't come down until all that palaver is over. RIGHT! Greg said: > Since Uncle Fred introduced it on the Ercoupe, a lot of planes have > included a trailing link suspension...look at the Rockwell Commander 114 gear > some time, or the Cessna 400-series twins. Again, trailing link has nothing to do with the airplane landing in the crab and turning to line up with the direction of motion. It only matters that the mains be BEHIND the center of mass and that the free-to-swivel nose wheel be in front of the center of mass and that the gear be strong enough to handle the transient side loads. Greg said: > You're close... you put the nose down once the airplane's nose is pointing > in the same direction that it's going over the ground. Otherwise you can > get a mighty swerve. Obviously, if you're headed for the boondocks, do > what you have to do, but you don't want to use the nose wheel > to knock the crab out...that's what the mains are for. > > You may make a little excursion off centerline. When you need nosewheel > steering, put it down. It's easier in the doing than in the telling, I think. Greg's pretty much got it right here, too. It is necessary to hold the yoke lightly (or take feet off the rudder pedals) to let that nose wheel swivel. If you do this, you'll have only a minor to moderate lurch then the plane will be lined up with the direction of motion. My experience was that I'd rarely deviate more than about 5' from the centerline (even in strong crosswinds) before the plane was lined up, nose down and under full control. Greg said: > Also, pushing forward on the yoke gets the thing to stop flying and can arrest > the Ercoupe tendency to raise the upwind wing as the crab straightens out. > Though this is usually exacerbated by trying to land too fast, or just by being > a 415D with only 9 degrees of up-elevator. It actually feels a lot more > alarming than it is harmful. Here, please let me disagree some. First, you should hold it off till you've reached minimum flying speed. Hold it off between a few inches and a couple of feet above the ground and you'll get some ground-effect dampening of gusts and turbulence AND be safely close to the ground in case of any downward excursion. As you touch ground, weight begins to come onto the main gear which is behind the center of mass so there is upward push from the ground on the mains and the plane comes level pretty promptly. I don't think I've ever needed to PUSH the nose down in these circumstances. Greg is right that any problems are exacerbated by trying to land too fast. I disagree that being in a 415-D with 9 degrees of up-elevator is a problem. I'd say the slightly higher touchdown airspeed in the 415-D is offset by the reduced elevator authority (because of having only 9 degrees of up-travel) and your nose drops quite nicely on its own. What you DO need is to have the landing gear donuts (or Belleville springs) in good shape (with spacers if needed) so that ON THE GROUND, the plane is level and the tips of the vertical stabilizers are at or close to 75" above the ground. As the airplane rotates to this attitude, the wings dump virtually all their lift and the up-wind wing won't lift. This leaves the nose wheel on the ground with good steering authority. If your tail is drooping, the up-wind wing has too high of angle of attack on the ground and it may lift in a strong wind/cross-wind. Make sure your landing gear has good donuts so you sit on the ground with the correct, very low, angle of attack. Greg said: > To me it's kind of like a taildragger, in the sense that you aren't done flying until you are > going fairly slow on the roll-out. In 1946, this made perfect sense to pilots. To modern > nosedragger pilots, the 'Coupe sometimes seems a bit squirrely, I think, especially as > it sorts itself out in a crabbed X-wind landing. You have to keep saying 'It'll be okay...it'll > be okay...' > > Also, like a taildragger, I find it useful to be really intolerant of deviation from the centerline > during the last stages of landing. While the 'Coupe is a tricycle gear plane, it is not quite > as mundane as a 172 or Cherokee, especially pedal-less. Funny as it might sound, it has > done my tailwheel flying a world of good. In general, I agree that you should fly the plane and be conscious of the winds until you have it parked or tied down, even in a Coupe. I would observe that, with the tail at the right height, the Coupe is the LEAST squirrely of any plane I've flown, once on the wheels. I've found Coupes to be MUCH more stable in the ground roll than a Cessna or many other planes - as long as the tail is up where it's supposed to be! Ed Burkhead http://edburkhead.home.insightbb.com/ [EMAIL PROTECTED] -----Original Message----- From: Greg Bullough [mailto:[EMAIL PROTECTED] Sent: Thursday, September 12, 2002 2:38 PM To: Mike Dean; Ercoupers Subject: RE: [COUPERS-FLYIN] FW: More on the Skyfarer ----[Please read http://ercoupers.com/disclaimer.htm before following any advice in this forum.]---- At 02:01 PM 9/12/02 -0500, Mike Dean wrote: >I was told once that the main reason the coupe could land in the kind of >crosswinds that most planes couldn't was because the main gear was >spring loaded and had some castering action to them. I'm still learning. Technically, you are both right. The gear itself does not caster. The WHOLE AIRPLANE casters as a result of the drag-link on the main gear. As the gear goes from the 'dangling' position moderated both by a careful pilot and by a combination of hydraulic dampers and one of two kinds of springs, there is increasing tendency to cause the nose of the airplane to agree with its direction over the ground. This tendency of a wheel on a trailing link to turn the object (or itself) in the direction of travel over a fixed surface is known as 'castor.' Since Uncle Fred introduced it on the Ercoupe, a lot of planes have included a trailing link suspension...look at the Rockwell Commander 114 gear some time, or the Cessna 400-series twins. Understanding the process helps you understand the crosswind technique as recommended in the book. Take off smartly, to minimize the 'argument' between the ground and the air, but land gently and keep the nose gear off to give the mains time to 'negotiate' direction of travel with the ground while the flying surfaces become more and more ineffective and of course try to ensure that the nose wheel doesn't come down until all that palaver is over. Greg ================================================================== TO UNSUBSCRIBE go to: http://ercoupers.com/lists.htm ================================================================== TO UNSUBSCRIBE go to: http://ercoupers.com/lists.htm
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