Trimming engine

[ricky]

Hi everyone,well im still haveing problem with my bc12d,ball is going to right
an you have to put half right rudder to go straight.
My question to anyone,hope hank is watching,I install so far 3 5/16 wash in the top/bottom of the engine frame mount to fire wall on left side.
We tract the wing to propeller is about 109in on both side,that from
end tip of propeller to the end of the trailing edge,but haven't install any washer to engine to frame yet.
Do I contiune to add washer to firerwall/frame,add washer to engine to frame,thank .
Rick

[perryv1]

Re: Trimming engine

Do you have to hold the rudder when your throttled back or gliding? I know I have a trim tab on the rudder that helps,Every t-Craft I ever saw had one.
PV

[mulwyk]

Re: Trimming engine

Rick:
Do you have a trim tab on your rudder? My project came with this one...not sure if it's original.

[Hank Jarrett]

Re: Trimming engine

Rick,

The guys are right. First step is to get the plane trimmed in a glide. Are the ailerons both level with the plane gliding and no yaw input needed while straight and level? The Taylorcraft has a lot of yaw/roll coupling and out of rig wings can make the plane out of trim in yaw too. You have to get both right.

First you should check that the wings are rigged the same. The right and left side should be at the same angle of attack at the root and the last full length rib just inboard of the ailerons. You don't have to measure the actual angle, just make sure both roots match and both last full length ribs match.

You can do that by putting a level on the bottom of the ribs on both sides and lifting the tail on a table with books and magazines until the levels are both level. When you are doing this you are NOT rigging the plane, but if they are different left to right you do NEED to rig the wings! Another thing to check is the deflection of the wings under load.

If you have a split in the aft spar at the root the wing may twist under load. Do you do a GENTLE twist and shake of the tip on preflight? Do both wings sound and feel the same? No pops, rattles or crunching sounds?

Once the wings are good, do you have a trim tab on the rudder? You should ONLY change the washers under the engine mounts if the yaw trim changes with power (a LOT, they all change a little). If the wings are good and it still yaws the same while gliding, use the trim tab. DON'T FORGET THAT MOVING THE TAB RIGHT IS LEFT TRIM!!!!! I HAVE seen someone keep adding more and more trim and only make the problem worse because he was bending the tab the wrong way! Tab goes left, rudder goes RIGHT, nose goes right.


Lastly, be really careful with those engine mount shims. The engine can start hitting the cowl and the crank can hit the edge of the bowl hole. There is also a limit to how many washers you can use. Don't forget you have to get it signed off when you change those washers too! That is NOT an owner maintenance item!!!! There are a LOT of potential side effects for lines and controls as well as interference problems.


Let us all know what you find and be safe. Get your mechanic to look at it before you fly. I am pretty sure this is major work under Canadian rules as well as US.
Hank

[ricky]

Re: Trimming engine

Guy,there is no trim tab on my plane,but I do have it,we just haven't install
it yet,the spar on left are brand new,came from talorcraft,right are still
original,still have data plate on it,we recovered wing,so ame did the inspection,the spar.
We found that tail verical fin to horrizontal stablizer was way out,we corrected that,she fly little better,but you still need little right rudder,
When I get home i'll install the trim tab,see what happen, but did see
that engine is about 1 to 2 inches off to the left on the nose bowl,that why ask if I should add washer to engineframe/or fire wall to frame on left.
Rick

[Hank Jarrett]

Re: Trimming engine

The prop flange is over an inch off center to the PILOTS side in the nose bowl hole?!?!
If that is true either the cowl is crooked or you may have a bent fuselage. Either way you don't fix it with washers under the engine mount. You need to Trammel the plane and find out how it is "bent" (if it is).
Trammeling isn't hard (actually it is kind of fun) and it will tell you just how far out of square your plane is. DON'T get upset as you start doing it. Taylorcrafts were built to +- 1/8" and yours WON'T be square! None of them are, but it shouldn't be TOO badly out of line. When I rebuilt my 45 fuselage I thought it should be perfect and spent a LOT of time pulling each bay back to square. It is probably the straightest fuselage in the tribe and now that I know better I realize it was a complete waste of time to work so hard pulling each part straight.
You will need to level the plane (I used the tube behind the seat and the root of both stabs) and then use a metal tape and a friend to help as you measure the distance from the top of the fin to each stab tip. The stabs should be level tip to tip with the fuselage. That makes the fin and stabs at a 90* angle.
Measure from the base of the fin hinge above the stabs to each wing tip rib (at the same place on both sides). They should be the same. Measure from the Fin hinge to the forward strut attach and make sure they are the same. Measure from the front strut attach to the center line of the forward fuselage on the firewall (I did this on a bare fuselage so it could be a problem on a flight configured plane, but what you are looking for is to confirm that the nose isn't bent to one side. Find a spot to measure to.) Next I would measure from the forward strut attach to the engine center line front and rear to see if the engine is offset or angled.
All of this is NOT a true "trammel" but it will show you if you have a badly bent bird. When I was doing aircraft appraisals we could do a quick "thumbnail trammel" on a plane in under a half hour. It was GREAT for spotting a bird that had been in an accident and was badly bent with a really "pretty" repair job. You can patch up a Cherokee 140 so it looks perfect and is crocked as a dogs back leg. Funny watching the seller trying to explain why there was no log entry and his tail was offset several inches to one side. Sometimes some major repairs are done with no log entries!
Hank

[n6346m]

Re: Trimming engine

I've said it before on this forum. Before you do anything check your tailwheel alignment. The tailwheel itself makes a hell of a trim tab since it is attached to the rudder. I had the same problem with my L-2B not flying straight and did not want to add a trim tab since it did not have one. The Scott 2000 I had then, and the Scott 3200 that I have now use the compression spring (spring within a spring). I simply took one link of the sash chain off one side and added to the other. It has since been flying straight and hands off. The nice thing about an L2 is that you sit in the center, both wing tanks feed at the same time, and you can rig it to fly hands and feet off all day or until it runs out of gas.

[n6346m]

Re: Trimming engine

Do you have to hold the rudder when your throttled back or gliding? I know I have a trim tab on the rudder that helps,Every t-Craft I ever saw had one.
PV

not mine

[Hank Jarrett]

Re: Trimming engine

We probably need to put a section in the new Taylorcraft maintenance document on trammeling a plane and I had completely forgotten about the effect of a tail wheel offset! It can be pretty exciting if your tail wheel isn't centered on touch down too! That swivel detent is important!
Hank

[KewFlyer]

Re: Trimming engine

Hank/Tribe:

Last Sunday I noticed that I was flying applying an unusual amount of right rudder in order to keep the ship flying straight [straight into a 4 knot wind]. Upon landing and when the tailwheel finally touched the grass, the plane veared towards the left and then when straight. After dismounting, we checked the tailwheel and found that the right spring was broken with the left spring pulling the tailwheel left; close to a 60+ deg. angle. I had a good trim tab !!!. Also noticed, that the tailwheel was not mounted straight and centered on the spring, either. Both items are for repair this week end. Using a Maule neumatic.

[astjp2]

Re: Trimming engine

Dump the Maule, go with a scott 3200. Tim

[jim cooper]

Re: Trimming engine

RE: tail wheel. I've had,on 3 different airplanes, a Scott 3200, a maule, and now a SMALLER Scott, almost new that came with the plane. All have worked well but.....they were all MAINTAINED well. Also: recently did business with East Coast Propeller in Litiz, Penna. Drove up there. NICE shop doing all kinds of repairs on CS props of many different models. Full service. I traded in my wood Sensenich for a new McCauley 74-43. Hallaluya! They are in Trade a Plane. JP