Tough Corners

[phil c]

Okay, here is a question for discussion.  I find the lower left corner of the square loops and the square eights especially difficult to pull tight.  The plane will pull all the other outside corners quite well, but the lower left wants to run wide.  I've seen this on several different planes, both flapped and unflapped.  Any thoughts as to what might be going on?

[Tom McClain]

It is called "God's G."

[Marvin Denny]

It is called "God's G."

  Please explain Tom --- You lost me.

  Bigiron

[Tom McClain]

An aircraft in level flight that seeks to change its velocity vector 90 degrees to the vertical must fight against earth's gravity or "God's G" force.  That is why Phil is experiencing the resistance to turn that he is.

[Dean Pappas]

Hi Phil,
The corners that bear comparing are the two bottom ones. The upper corners will, of course, have some help grom what the 4-year old next door calls "grabbity". Now for the fun, the difference between the 1st and 4th corner in a square loop must be the difference in airspeed going in and coming out. Both corners involve making a bunch of lift and drag, but the loss of altitude, and exchange of potential energy for kinetic/drag, in the 4th corner means that the plane exits with more of its entry speed as compared to the 1st corner. We need horsepower that jumps up even as the nose starts turning. Now we're back to the old trick John D'Ottavio told me about moving the tank as far back as practical.

hope that muddies the water for a bit!
Dean P.

[John Sunderland]

You need flaps.....big wing, power to weight ratio is equal or nearly so.... my Magician does the same at 9% above a 1:1......just my take on it. I know you fly your bird super light with gobs of lift but it seems like a CG to tip weight anomaly to me.

[Howard Rush]

It shouldn't be any worse than the inside corner on the other side of the square 8 or the fourth corner of the inside square loop, both of which are at the same angle to the wind, and certainly no worse than the last corner of the hourglass.  My guess is that there's a problem getting enough control deflection-- it is probably the outside corner that happens at the highest airspeed. 

[Al Rabe]

And, of course, gyroscopic precession is reducing line tension in all outside corners.

Al

[Tom Niebuhr]

Dean,

You are right on. John taught me that one when I was still in my teens, The aft tank really made the old Foxes break into the 2 cycle faster.

[Steve Helmick]

"I find the lower left corner of the square loops and the square eights especially difficult to pull tight.  The plane will pull all the other outside corners quite well, but the lower left wants to run wide."

Phil's first sentence from the snip above lead me to think he meant the inside corners. The second indicates otherwise. I'm sure he flies counterclockwise (from combat background), but flying clockwise would also warp the meanings, of course. If I got any of this wrong, please clarify.

Speaking of warps...but maybe too much tip weight or LO's too far forward. When we had our Stunt Clinics, our test pilot (a high ranking PAMPA official) said that almost all planes had too much tipweight. Couldn't just be nerves, right?  Steve

[phil c]

I'm talking outside corners here.  No problem on inside ones.

One thing to add, moving the maneuver up to 12-15 ft. seems to allow the plane to take the corner more sharply.  I'll have to get it on tape to be sure though.

[Joe Yau]

I'm talking outside corners here.  No problem on inside ones.

One thing to add, moving the maneuver up to 12-15 ft. seems to allow the plane to take the corner more sharply.  I'll have to get it on tape to be sure though.

Did you check the pushrod for flex?  just pull on the down line tight and try to put some force on the rear elevator towards neutral/level position.

[Marvin Denny]

  More than likely it is the hand position in relation to the body.  I find the bottom right   Corners of the outside harder .  I am left handed normally, but when I fly with my right hand, the lower left corner seems to soften up considerably as opposed to left handed flight.  It is mostly in the way you rotate the wrist when giving the "down" input to the controls.  That is assuming everything else is normal  ie.  no  pushrod flex,  hinge lines sealed, thrust and control center lines good, same amount of up and down etc.

  Bigiron

[phil c]

I'll fiddle with the handle layout a bit.  Maybe making the down line overhang a bit longer will give it more leverage.  It isn't the pushrod, because the pushrod is being pulled for down, and I can see the elevator getting good motion.