rigging

[swoeric]

I used the search function and found an overwhelming amount of information. I was wanting to know if there is a concise guide to rigging..

example

a list of test to verify a starting point...

Flying power off to determine skid or slip and correct rudder tab for this...bend left for (what reaction)

Is there an order for adjusting wing struts or something to do before hand?

If possible could somebody point me to a post that would take me from beginning to end on inspection of squareness and rigging and what to adjust for different circumstances.

I would like to take a systematic approach while in annual this year to accomplish a hands off level flight if possible...Right now mine roles to the left a bit or require some rudder





Thank You
Eric

[Hank Jarrett]

Re: rigging

This is a perfect topic for a chapter in the maintenance guide. The whole process is called "Trammeling" and is more involved than just getting the wings at the right incidence angle.

The first step is to level the plane fore and aft and side to side using the horizontal stab and the at seat cross tube and MEASURE THE WEIGHTS FOR A TRUE WEIGHT AND BALANCE! If your CG is off the plane WON'T FLY RIGHT! Watch for a "heavy wing" too!

Next you rig the tail surfaces with the wires to get the tail surfaces level and perpendicular (these settings WON'T usually last and the tail surfaces will shift a little after a few flights. You have to go back and "chase" level and perpendicular" for a while until everything settles in).

Next you pull a level line between the wing tips to see that you have equal dihedral in both wings. While the fuselage tube and tail are level, the string should be too. Good luck if it isn't, the Taylorcraft doesn't have a way to correct this, but you still want to know how far off you are so you don't chase other things trying to correct for it.

Next you check for the proper twist in the wing by adjusting the aft struts on both sides. As you do each step, keep going back and looking at all the other measurements, because unless you are some kind of holy man you WILL have knocked them out while working on the following steps! You have to continuously keep checking level through the process.

Next you make sure all the controls are set correctly with the right "sag" in the ailerons and tension in all the cables.

Lastly you should check the thrust line to be sure the correct "Right Thrust" and "Down Thrust" are there on the engine.

Hank

[Hank Jarrett]

Re: rigging

There are more details to this than space here allows, and notice that I DID NOT say what the correct measurements were. A lot of them I don't know yet! I'm not sure who does, but that is what I want to do flight testing for. I put a LOT of work into the 45 fuselage so that is is DEAD ON straight. EVERY BAY is straight and it should be VERY close to the drawings.
Hopefully I will find what the measurements SHOULD be before I put her back together.
Hank

This should be open to discussion since I am pretty sure I will have probably missed a few steps.

[Hank Jarrett]

Re: rigging

Oh yea. You also need to pull a line from the fin hinge tube to each wing tip to make sure the sweep is the same in both wings. If one wing is angled back more than the other the turning behavior will be different depending on which way you turn. You also need to align the wheels (a lot of poor landing planes are poor because the wrong "toe" and "Camber" is in the gear. The vertical angle at the tail wheel pivot is also critical as well as the steering spring tension. Want a REALLY fun plane? Check the tail wheel tire bolt and bearings. A loose or angled axle will make for some "interesting" arrivals! Wobbling tail wheels are NOT nice, and it doesn't take much.

Another thing to look for in the tail is a missing front spring bolt bushing. If it is gone the tail spring can rock back and forth for unexpected excitement. Again, it doesn't take much, and tightening the bolt does NOT eliminate the problem. The stinking little bushing can fall out and not be seen when the tail spring is removed. DON'T LOOSE IT!

Hank

In case anyone is interested, I have probably messed up every one of these things. The trick is to catch it before you fly and only mess up each thing ONCE!

[Pearson]

Re: rigging

Also, the procedure for setting a starting point on the washout of the wings is in the Service Manual.

[1938BF50]

Re: rigging

I rigged my wings per the manual. The manual gives the specifics for a distance of rise between the spars fore and aft. I taped wood blocking to my 4' level so that it was just a visual instead of having to hold a level and measure at the same time. This made it a very easy "one person" job. My wings were darn near dead on during the first flight tests. I adjusted one wing a half a turn after which it flew perfectly level. I HAD a perfectly straight fuselage and thought I might get away without an ugly trim tab on the rudder. Not so, I had to use very heavy right rudder to fly straight.....so heavy that it was slightly scary at first(and very uncomfortable). I dug out the old trim tab, found the old holes in the rudder and mounted it as is. Next test flight it flew hands and feet off.

[ricky]

Re: rigging

Hi hank,remmeber talk to you about how my plane alway bank left,you mension this tramming,the real problem was the engine mount on left upper,lower tube were bent,that why my plane
alway bank hard left,we straighten the tube,an added two washer on top,bottom left at the engine to mount,Rick

[Hank Jarrett]

Re: rigging

These planes were built to +-1/8". Amazing how much difference 1/8" can make in some places.
Hank

[astjp2]

Re: rigging

Wow Hank, you want a perfect airplane but the fuselage jigs were barely within 3/8" of each other.....Tim

[Hank Jarrett]

Re: rigging

That's what I found out after I got all anal about getting my fuselage straight. There are few areas of the planes where the tolerances are very tight, CERTAINLY not the squareness or straightness of the fuselage between the wing attach and the tail surfaces. When you think about it, there isn't REALLY any reason to worry about how close the mold lines of the fuselage are as long as the basic alignment of all the flight critical components is close. You want the thrust line, wing incidence and twist, gear contact points and alignment and tail surfaces to be within trim-able limits, but if one fuselage is bumped out on the pilots side and in on the passenger (banana fuselage) it would have to be a LOT before the rudder trim tab couldn't be bent to correct it, IF the gear, engine and flight surfaces are all straight. Getting the non-flight critical parts perfect is really not productive and explains why a lot of times doors and windshields are not interchangeable.
Trammeling is still important, but that focuses on the relationship between the critical parts.
Hank