Phil
Well Known Member
As some of you know, I have been slaving away in the shop working on rudder trim for my -10. This was my first deviation from VANS plans and as I learned, when you're working off a blank canvas, things go MUCH slower.
I thought rudder trim would take 3-4 days and I'd be on to the next thing. The truth is, it took me 3 weeks. Not so much beause it was difficult, but because I would come to a road block and have to take a break for the night. Usually, by the time I woke up, I'd have a soluton. Then it was back to the shop until I hit the next road block. When you're off the beaten path and your doing your own design, there seems to be many obstacles.
Let me start by saying thank you to Vic Syracuse for helping me through some of my builder rookie questions. I took his Rudder Trim design and refined it a bit. Vic was a great help!
With all the respect of those who have gone before me, I had a couple of goals.
A) I didn't like the screw forest on one side of the rudder. I don't like having the door screws mixed in with the servo screws. To my eye, having them all grouped together looks unorganized. I started this project trying to avoid the "Honey I shot the rudder with a shotgun" appearance. Painted or unpainted screws, that was simply a look I wanted to avoid.
B) The servo isn't mounted parallel to the rudder stiffiner holes. So you end up with holes that just don't look straight. One screw is higher than the other. It just didn't appear real organized.
C) I wanted the exit fairing to be level and I wanted the push rod to exit the rudder level too. I don't like having the fairing angled upward (perpendicular to the Trailing Edge).
In general it needs to look clean and the lines need to be consistent with the airflow across the plane. Your eyes sweep the countours of the plane from front to back and the rudder trim needed to blend in with those lines - not stand out.
So off the to shop........
First I made some test fittings of the trim tab and the servo. I found that the traditional "L" brackets just didn't work too well. The clevis kept bottoming out on the bracket when it was fully extended. So I came up with this design. It allows the clevis to rotate around the "L" brackets with clearance beyond the .7" that the Ray Allen T2-7A servo travels.
Next I found that if I wanted the push rod to run parallel to the ground, it would still bind on the sides of the brackets because it was pushing them at an angle and not in-line. I came up with bending the ears on the L-brackets to match the angle created by the trailing edge of the rudder and the stiffener lines.
If you look closely at this photo, you will see two lines. The red one is perfectly perpendicular to the trailing edge. The black one is drawn parallel to the stiffiner holes. This is the line I want the push rod to operate on. I clamped the brackets together and laid them against the trailing edge. Then I used a hand seamer and put a bend in the ears so they matched the black line. (Look closely, you'll see they are angled a hair to the right.) - After I completed the bend, I drilled the 1/8" hole for the clevis pin to ride in.
You can see how the clevis rides on the brackets in this photo.
So that took care of the problem of getting the servo mounted squarely, having the push rod run parallel to the stiffiner holes, and have the fairing be mounted perfectly in-line with the lines of the aircraft.
(Continued in the next message)
I thought rudder trim would take 3-4 days and I'd be on to the next thing. The truth is, it took me 3 weeks. Not so much beause it was difficult, but because I would come to a road block and have to take a break for the night. Usually, by the time I woke up, I'd have a soluton. Then it was back to the shop until I hit the next road block. When you're off the beaten path and your doing your own design, there seems to be many obstacles.
Let me start by saying thank you to Vic Syracuse for helping me through some of my builder rookie questions. I took his Rudder Trim design and refined it a bit. Vic was a great help!
With all the respect of those who have gone before me, I had a couple of goals.
A) I didn't like the screw forest on one side of the rudder. I don't like having the door screws mixed in with the servo screws. To my eye, having them all grouped together looks unorganized. I started this project trying to avoid the "Honey I shot the rudder with a shotgun" appearance. Painted or unpainted screws, that was simply a look I wanted to avoid.
B) The servo isn't mounted parallel to the rudder stiffiner holes. So you end up with holes that just don't look straight. One screw is higher than the other. It just didn't appear real organized.
C) I wanted the exit fairing to be level and I wanted the push rod to exit the rudder level too. I don't like having the fairing angled upward (perpendicular to the Trailing Edge).
In general it needs to look clean and the lines need to be consistent with the airflow across the plane. Your eyes sweep the countours of the plane from front to back and the rudder trim needed to blend in with those lines - not stand out.
So off the to shop........
First I made some test fittings of the trim tab and the servo. I found that the traditional "L" brackets just didn't work too well. The clevis kept bottoming out on the bracket when it was fully extended. So I came up with this design. It allows the clevis to rotate around the "L" brackets with clearance beyond the .7" that the Ray Allen T2-7A servo travels.
Next I found that if I wanted the push rod to run parallel to the ground, it would still bind on the sides of the brackets because it was pushing them at an angle and not in-line. I came up with bending the ears on the L-brackets to match the angle created by the trailing edge of the rudder and the stiffener lines.
If you look closely at this photo, you will see two lines. The red one is perfectly perpendicular to the trailing edge. The black one is drawn parallel to the stiffiner holes. This is the line I want the push rod to operate on. I clamped the brackets together and laid them against the trailing edge. Then I used a hand seamer and put a bend in the ears so they matched the black line. (Look closely, you'll see they are angled a hair to the right.) - After I completed the bend, I drilled the 1/8" hole for the clevis pin to ride in.
You can see how the clevis rides on the brackets in this photo.
So that took care of the problem of getting the servo mounted squarely, having the push rod run parallel to the stiffiner holes, and have the fairing be mounted perfectly in-line with the lines of the aircraft.
(Continued in the next message)