Rigging Question?

[VictorBravo]

Re: Rigging Question?

The fixed trim tab will solve only one end of the problem, and make the other end slightly worse. If you have nose-down trim bent into a fixed tab on the elevator, then you also have nose-down trim working against you when you are trying to trim nose-up on landing. This would make the external "popsicle stick" trim tab even more over-worked and ineffective.

Since the trim tabs just bolt on, I think it will be a nice experiment to make up a set of slightly larger tabs that are more aerodynamically balanced and have an airfoil. The goal is to have the trim tab airfoil level, but making enough lift to trim the plane at cruise, then have enough power in the tab to slow it down to final approach speeds when drag is not a concern.

Thankfully, these sorts of experiments can be done without altering the original parts. If I find something that really works well, I can submit it for official blessing.

[peerlesscowboy]

Re: Rigging Question?

Somewhere above on this thread, quote from the Service Manual:

"In flight testing,-------------"

"If the airplane flies nose heavy, both wings may be washed in, or if tail heavy, both wings may be washed out for correction." ????

Prob'ly demonstrates my ignorance, but shouldn't the opposite be true?

John C. Saubak

[Gary Snell]

Re: Rigging Question?

John, if you think of "washing in" as increasing the angle of attack, it would tend to raise the nose and compensate for a tail heavy condition.

[Forrest Barber]

Re: Rigging Question?

For drude ?? THAT is the correct drawing for the correct wash out... 1 & 5/16th in. Sure you can do other stuff but that is the correct rigging procedure.
ALL mechanics should have a good copy of the Service ( Owner's) Manual for the BC12D if they are working on them; Wag-Aero or Univair or Essco...
I repeat: the closed cowl ship will not trim out with only the flippers, then there were two shapes of trim tab used on the elevators on the pre-war ships I have both laid out to photo....

[alwaysoar]

Re: Rigging Question?

I'm going to take a stab at answering peerlesscowboy's question, "shouldn't it be the opposite"? (Don't be mean if I screw this up--I've had a bad day)

If a wing is washed in, then the angle of incidence is increased. That effectively increases the angle of attack in flight, though they are not the same thing of course. The greater angle of incidence is going to move the center of lift forward along the cord of the wing in flight thus decreasing the nose heaviness because with the greater angle of attack, the plane will try to climb, assuming the same airspeed as before the adjustment.

Ed@BTV VT
TF527

[VictorBravo]

Re: Rigging Question?

Please forgive me for butting in on the wash-in comment, but I want to make it crystal clear that any wash-in creates two safety problems.

First, it will make the wingtips stall before the rest of the wing, which is OPPOSITE of a safe condition.

Second, in EXTREME conditions it will increase the bending loads on the spars because more of the airplane's weight (or "4 times" weight if pulling 4G in turbulence) is being carried by the outer section at a higher AOA.

In my opinion, the wings on a Taylorcraft (or any other) should not be adjusted so that the wingtips are at a higher angle of incidence than the root. Either zero, or a little wash-OUT.

Wash-in is a trick that free flight model airplane builders use to get gliders to roll into a thermal on their own, because the wingtip will stall faster and DROP the wing to turn the plane into lifting air. Early R/C modelers (who were all free flighters anyway) used it to increase the yaw/roll coupling on rudder-only models in the 1940's and 1950's.

[Guest]

Re: Rigging Question?

For drude ?? THAT is the correct drawing for the correct wash out... 1 & 5/16th in. Sure you can do other stuff but that is the correct rigging procedure.
ALL mechanics should have a good copy of the Service ( Owner's) Manual for the BC12D if they are working on them; Wag-Aero or Univair or Essco...
I repeat: the closed cowl ship will not trim out with only the flippers, then there were two shapes of trim tab used on the elevators on the pre-war ships I have both laid out to photo....

Thanks Forrest, I'll make note of that and ignore the other page. I guess I have an imitation servicew manual. Dave.

[Guest]

Re: Rigging Question?

Please forgive me for butting in on the wash-in comment, but I want to make it crystal clear that any wash-in creates two safety problems.

First, it will make the wingtips stall before the rest of the wing, which is OPPOSITE of a safe condition.

Second, in EXTREME conditions it will increase the bending loads on the spars because more of the airplane's weight (or "4 times" weight if pulling 4G in turbulence) is being carried by the outer section at a higher AOA.

In my opinion, the wings on a Taylorcraft (or any other) should not be adjusted so that the wingtips are at a higher angle of incidence than the root. Either zero, or a little wash-OUT.

Wash-in is a trick that free flight model airplane builders use to get gliders to roll into a thermal on their own, because the wingtip will stall faster and DROP the wing to turn the plane into lifting air. Early R/C modelers (who were all free flighters anyway) used it to increase the yaw/roll coupling on rudder-only models in the 1940's and 1950's.

Hi Bill,

I don't dispute anything you say. I do wonder if they manufacturer would give me and adjustment that would allow me to alter the angle on incidence enought to make a situation as you describe.

I did some real quick geometry from memory of approx. dimensions just to get in the ballpark.

It looks to me like the most I can alter the angle of attack is about .5 degrees.

So if I assume that the screw turned all the way out is the standard angle setting and the smallest angle of incidence and the strut is the longest possibe

Then the worst case is I screw it in all the way and I could make the angle of attack increase by .5 degree, could be by that amount on both wings or just one.

.5 degree is the max delta. Does that much change make a big difference? I am away from home and my airfoil books are there so I can't look for a few days.

Of course we don't know what the twist in the wing is with the screw all the way out, least I don't. That's got to be a big factor too.

Anyhow, ya got me thinking.

Thanks, Dave.

[dedrekon]

Re: Rigging Question?

Does anyone here have a source for the threaded plugs used to wash the wings in and out. I've recently ran across a couple of people who are looking for them.

[Guest]

Re: Rigging Question?

Does anyone here have a source for the threaded plugs used to wash the wings in and out. I've recently ran across a couple of people who are looking for them.

Over the last 8 years I have replaced them in 3 ways 1) sleeved and redrilled to remove bolt hole slop 337 was submitted 2) fabricated a new screw from .125" wall 4130 tubing, threaded it, drilled it... 337 on this too 3) got new screws that were pretty useless, hole was off center & not square with the axis so it would not line up with slot in the strut or wing fitting. Still have them.

#2 worked out best all you need is a die, some tubing, drill press and patience.

Dave.