Vagabond Rudder Trim???

[BrettL]

Is there any recommended method for adjusting rudder trim on the Vagabonds? My PA-17 has required holding a small amount of right rudder pressure during cruise flight. I don't see anything in Service Memo 14 regarding this. I have noticed that each of the "rudder cable rear fitting assemblies" have 5 holes in them where they attach to the rudder horn. Could this be a method provided for making rudder trim adjustments? Even though I doubt it, I'm wondering what the 5 identical holes are for if only one is to be used. Any ideas?

I have seen the method from the service memo for the Pacers of twisting the vertical stabilizer, which sounds a bit scary to me.

[tnowak]

Having owned my PA-17 for 30 years now, I have found my right leg is approx. 1" longer than my left leg!
I don't think it can be adjusted out (easily) though I suppose you could try using a slightly shorter stbd rudder cable to "force" a bit of right rudder.
Tony

[Steve Pierce]

I would apply a moderate force to the top leading edge of the verticle fin to the left. You will be amazed. Just look at the fabric as you do it and you won't go to far.

[BrettL]

I don't think it can be adjusted out (easily) though I suppose you could try using a slightly shorter stbd rudder cable to "force" a bit of right rudder.
Tony

It looks like the 5 holes in the "rudder cable rear fitting assembly" could effectively accomplish the same as slightly shortening or lengthening of a rudder cable (about 1/8 to 3/16 of an inch with each hole), giving the ability to effectively lengthen or shorten each side by approximately 3/8 of an inch. The question is then, will the centering force of the rudder return springs have enough effect to change where the rudder aerodynamically centers?

I found that someone had substituted apparently incorrect rudder return springs on my bird. These have been replaced with the correct item from Univair, but I haven't had a chance to fly it yet to see if I can tell any difference. I also found that the left "rudder cable rear fitting assembly" was not connected to the rudder horn using the center hole. Some experimentation may be in order.

[JohnW]

Ehhh, they CAN BE rigged to fly straight and level. If you Vagabond flies VERY SLIGHTLY with the "ball to the right" (half a ball or so), most of the time you "adjust for this". If you need to "hold right rudder", then clearly what you are witnessing is "adverse yaw". Now WHAT causes adverse yaw??? (You can do it!). Needing to "push the tail to the right" means that there is "more drag" on the LEFT SIDE of the airplane. What do you do? Well, you can either "remove some drag on the left side", or "add some drag on the right side". You do this with the "rear strut fork". Making the left rear strut fork "a little longer" will remove a little washout from the left wing. This "flattens it", streamlining it in the process, resulting in "less drag on that side". Conversely, adding a little MORE washout to the right wing adds a little more lift, AND drag, to that wing, so it becomes a question of "choice" as to which you prefer. How much it takes, is a function of how much it NEEDS.

Now (this is where the Post starts to "get long"...) an airplane with "more washout" than required in BOTH wings will fly just a tad slower. Since the Vagabond is "no rocket" anyways, I actually PREFER slightly more washout, as the airplane touches down slightly slower, with the wing stalling "later" at the tips. But, it cruises a couple mph slower. So, IMO, no biggie (where you going, "fast" in a Vagabond, anyway???). I LIKE a "later quitting" Vagabond for landing shorter and taking off slightly earlier.

"The key" is to get the airplane flying "wings level", with the ball "in the cage". First off, in a Vagabond, having the right seat "empty" vs having a warm body next to you means that you will have to "just keep one foot on one or the other rudder pedal" depending on how you are loaded (this with the single, stock "fuselage fuel tank"). ANY airplane will "drop one wing" with more weight on one side (fuel, or peoples, or a fold-up bike in the baggage compartment...it don't care), and in small airplanes with no "in flight trim available", life is going to be a trade-off. If you fly ALONE 95% of the time, rig your airplane to fly hands off at cruise with no one "in" with you. If you regularly fly "Mama", then tweak it so you can leave your feet on the floor with her in there with you. But, back to the relevant statement, you want the airplane to fly WINGS LEVEL when the ball is in the cage...and if you need to hold rudder to keep both wings the same height above the horizon, then you need to rig the back strut(s). FIRST.

What you DON'T do is to bend your vertical stab just because your airplane "flies a little crooked", or "wants to roll one way" hands off. This is INEFFICIENT FLIGHT, and instead of you getting to "choose your poison" (slow cruise and touchdown, or faster cruise with a earlier wing stall), you lose BOTH WAYS. What you NEED to do is get it into proper rig, so that AT CRUISE, hands off the stick and feet on the floor, the airplane flies with the same "gap of sky under both wing tips" AND the ball is in the cage. Now, you MIGHT JUST FIND that when you get the wings flying level, when you lift your feet, the airplane skids. This will cause (or...be CAUSED BY) "the opposite wing" to RISE (rising), and the airplane turns whichever way it SHOULD (because BANKING turns the airplane, not YAWING. Hell...banking YAWS THE AIRPLANE! But! so does drag.). If when you are holding the wings level with a slight rudder input you CAN'T rig the wings to make the airplane fly straight, then you have a "twisted airframe", and eventually you will have to "give in" and tweak the tail to one side (but this "comes later", after you work for it). Now the BEAUTY of having the wings "rigged correctly" is that a LARGE AMOUNT of "out of true" of the vertical stab isn't required once you get as close as you can to "ball in the cage", to correct for various "reasons" that cause the skid! That means that "fabric wrinkles" are NOT an issue. If you have to bend the tail SO MUCH that you leave wrinkles in the fabric, you are NOT "rigged correctly"!!! One possibility is that the tail surfaces are not "true and plumb" to start with, and when you begin rigging, you MUST "start there" to at least CONFIRM that the tail is "square". If it isn't, don't waste your time at the struts! You absolutely cannot "count on" the last guy having done it right. Rigging is not "easy". It's not "quick", either. Getting "good tension on the tail brace wires" cannot come at the expense of unplumb, unlevel tail surfaces. It takes an ARTIST to rig an airplane correctly, and many "test flights" to see exactly what your last "tweak" DID. Plus, I need to stress that this is NOT "owner maintenance" on a certificated airplane, and you NEED a licensed mechanic involved. You can't "chase your struts around" until there are not enough threads in the strut barrels, or you will shed a wing. Seek Professional help. You MAY need to "start all over from the beginning per the Rigging Instructions", and possibly more than once, if you get too "crazy" making adjustments. EVENTUALLY, you will begin to understand what your "inputs" do to the "problem(s)". When you do get to this point, finally, it may be a darn good idea to "start again" ONE MORE TIME so you know you are correct. The Rigging Instructions are there to gaurantee you a "safe airplane setup" for the first test flight. Once you "see how it flies", you then "tweak out the anomalies" so the airplane flies dead straight at cruise. If after TEN TIMES through the process you haven't gotten the ball in the cage and the wings flying level, then either you (or your Pro) are not understanding what your effects are having, or you have to bend the fin just a little. Here is where a REALLY GOOD OLD TIMER that understands "Friggin' and Riggin" is worth his weight in Gold. There is NOTHING more pleasurable that flying around on Dawn Patrol (or a Dusk) on a still day, with your feet on the floor and your hands in your lap. But you CAN "have this". The nice thing about this is...you get a perfect excuse to FLY your Vagabond (not that any of us really needs an excuse...).

Those "five holes" in the aft rudder cable fittings...have NOTHING to do with whether you need to hold pressure on the rudder pedal in flight. Nothing! They allow "snug positioning" of the cables with minimum "droop" when there is nobody sitting in the airplane. Whenever you are "operating" the rudderbar (have even ONE foot on a pedal), YOU "are tensioning the cables" with your clodhoppers. If the rudder return springs aren't "dead", the rudder cables won't "hang down to the ground" static, but you do not "position" the rudder with those holes. Those holes are to "take up" Production tolerances when Piper built the cables, the rudder pedals, the rudder, and the fuselage, and that is the ONLY REASON they are there.

[Stephen]

Whew....

and make sure that the instrument (Ball, in this case) is installed corectly....... level with the fuselage.

[stevesaircraft(Bri)]

Question,

Would my rudder trim system work on the Vag??

http://www.stevesaircraft.com/ruddertrimstc.php

If so, I could probably get it approved on them.

Brian.

[JohnW]

Jeez, I'm not really sure, Brian. I'm not familiar with what kind of "monkey-motion" you needed to make to complete the interconnect on the later model shortwings, but I DO know that the Vagabond has it's original fuel tank sucking up a LOT of space forward of the instrument panel (same "basic part number" tank as the Clipper fuselage tank). There is virtually "no room" between the tank and the firewall and "little" on the sides. You'd hafta crawl in one for a minute and lay your belly on the pax seat in a Vagabond or a Clipper and see if any of the "places" your interconnect traverses are blocked by the fuel tank. Only a few Vagabonds even have ONE "wing tank" installed (they weren't an "option" from the Factory) and only a COUPLE have the center (fuselage) tank removed. At the original 3.8 gallons per hour fuel burn with the Lycoming 65, there was PLENTY of fuel available (and let's not forget that the Vagabonds were a "lesson in barebones" for Piper) with the one tank. "More fuel" wasn't much of a "necessity" either, since with no electrics (and "no ground speed" to speak of) they have never been "much" of a cross-country airplane. Then there was a "no gross weight" issue, a couple normal sized humans and ten gallons of gas, and you are bumping up against 1100 pounds gross (mine weighs 646 empty with right side controls and rudder pedals and no fuel in the tank) before you put one suitcase in the baggage compartment! Then there's the sticks "swingin' around" under the panel. That would limit where the "control head" would be mounted.

Can't say "Yes", and can't say "No" with any certainty. I CAN say that a Vagabond is the perfect airplane to show a "first timer" how leaning forward or back, or side to side (or opening the pax door) affects the trim of an airplane!

[d.grimm]

John,
Just got done rigging my Vagabond according to the rather primitive rigging instructions. Being a jet mechanic in a previous life I tend to be a "little" anal when it comes to these things and used my digital level to a tenth of a degree. I am looking for shortest takeoff and landing distance, what would you recommend when it comes to wing washout and aileron droop (within legal parameters)? 85hp, two twelve gallon wing tanks, and a W72GK44 prop. Hoping for 700 empty weight.
Thanks,
Dave

[N4567A]

Jason and I are chasing the trim of mine around. Pretty close now just a slight tendency to turn left when feet are on the floor and hands off the stick. Guess it just takes a bit of time.
Rodg

[BrettL]

Those "five holes" in the aft rudder cable fittings...have NOTHING to do with whether you need to hold pressure on the rudder pedal in flight. Nothing! They allow "snug positioning" of the cables with minimum "droop" when there is nobody sitting in the airplane. Whenever you are "operating" the rudderbar (have even ONE foot on a pedal), YOU "are tensioning the cables" with your clodhoppers. If the rudder return springs aren't "dead", the rudder cables won't "hang down to the ground" static, but you do not "position" the rudder with those holes. Those holes are to "take up" Production tolerances when Piper built the cables, the rudder pedals, the rudder, and the fuselage, and that is the ONLY REASON they are there.

??? The springs take up the rudder cable "droop". I can't see how 3/16" is enough to make a cable droop or not when the other end is connected to a spring under tension.

[JohnW]

Well, Andy...at least you have a decent starting point. Each and every airplane has its own "perfect setup"...there ARE NO "majic angles or degrees. (Production Tolerances, My Friend!). First, get it flying straight and level. Opt for "increasing washout" rather than "decreasing the draggy side" for getting the ball where it belongs. AS far as the aileron "droop" goes, I played with that a WHOLE BUNCH thirty years a go, on both a Vagabond and a 22/20. I settled on finding out that Piper had the best "all around" adjustment...when the ailerons are both in trail with the wing at cruise. I played with about a 6 to 7 degree "reflex" on the converted Pacer flaps, and got about 8 mph for my efforts. BUT...the airplane was so "wishy-washy" in slow flight (flaps up) that it wasn't worth the time foolin' around with it (the reflex idea came from the Maule "cruise flap setting", but they did some tricks with "adding more UP" into the control linkage, rather than "cheating neutral" or lessening "down"). Now, when the cable tension is "correctly looser than you would expect" (the stick moves like silk), this will mean that sitting still on the ground, the ailerons will droop from about 1/8" to 1/4" BELOW "dead flush in trail" (all the shortwings). The "important part" is "perfectly in trail, in cruise". THAT is where they work the best under ALL conditions (whaddaya know, Piper knew something about what they were doin'!" Go figger.).

Once you're "hands off in cruise", you can start "adding washout" a turn at a time. What will "limit you" is NOT GETTING THE FORKS TOO FAR OUT OF THE STRUT BARRELS. I'm sure from my experiences that the "best extra washout" is no more than about a "couple/three" turns more than "rigged nice from scratch". This will give you a NOTICEABLY increased "forward lean down" at the tip end of that stubby little wing... It won't BE much more than about one degree, but it will LOOK LIKE much more, in level flight! You will see that you don't need MUCH away from "rigging by the book" to influence how the wing tips will "hang on" (or, shooting for
more cruise by flattening them out... about the same from "initial rig" will be WELL into the "drops onto the runway" stage. "Quits flying abruptly" when "flat"). Just "stay as close to book rig" as you can to get it hands off, but not by "walking it up like a ladder"... not by just "doing things willy-nilly". Get comfortable with "what each adjustment you make DOES", and return any "mistakes you make" (like going the wrong way with an adjustment) to where it BEFORE rather than "doubling the same action on the other side". Get me? In fact, since you're "didgicrazy", at this point, shoot the airplane AFTER you get it hands off, and see just how much (or little, as the case may be!) you actually "changed it" from "the Book". You'll be surprised. I KNOW this to be true. If you THINK you've got it "screwed up"...you do. Start over (and leaving the "tenth of a degree" in the tool box, this time. You're gonna THINK it's "right on the money" the first time you fly it. It's not. It never is. You have to "tweak every airplane in", and it's worth it.

So, once you get it hands off, increase washout the same "number of turns" on each rear strut, and go shoot some landings. Start out with "full turns" on the forks (that's the "easy way", because you don't have to remove the fork from the fuselage, just loosen the lock nut at turn the strut over one turn, then put the upper bolt back in -and tighten the fork lock nut), and when you are happy with the flight envelope, put enough landings on 'er until you stop blaming the airplane, and learn how it REALLY wants to land! When you got THAT pegged, then "tweak some more" by turning the forks HALF a turn. When you find "max float", you will LIKELY want to "back off" a little on "max short" TOs and Lndgs, so you can LAND the Thamb Ding when it's sunny and hot! By then, you will know the airplane like the back of your hand.

When you get to THAT POINT, lemme know, and I'll tell you how to REALLY get off short with it. Scary short...tears in the eyes of a SuperCub driver, short. Accused of having JATO bottles hidden somewhere, short. Now, don't try this without Adult Supervision (and I won't tell you any of this "in Public" where just ANYbody can read it, and go out and hurt themselves -or wreck a Vagabond!). There'll be one "test question" that the answer to which will tell me you have "mastered the bottom end of the envelope". You are about to learn why you are REALLY GLAD you bought a Vagabond, and understand why "all the work you put into it" was worth every minute. Too, you'll understand why MINE will never" be For Sale" until the Big Garage Sale Annie will have when I'm finally gone. There is just about NOTHIN' that goes less than 450 knots in cruise that is more FUN TO FLY than a Vagabond (and the 85 makes it "stellar", while even the screamin' Lyc 65 is PLENTY of engine -at less that 2500 MSL).

Okay, I got a question for ya, before you start all this...where's the CG (aft of the wing LE, aft of the REAL Datum, I don't care "which")? This has to do with the 85 upgrade more than anything else. How much ballast did it want?

[BrettL]

By the way, just eyeballing the top of my vertical stabilizer it appear to have a degree or two angle to THE RIGHT. Sighting along it from behind, it appears to point about half way between the center and right side of trim strip along the top of the windshield.

[Steve Pierce]

It should point a bit left. Look at a Corsair and you will see the vertical fin is offset quite a bit. Piper kicked the engine mount over 2 degrees to the right I assume to take up for the "P" factor of the propeller but I have been told and it has worked out to point the top of the vertical a little to the left of the center of the windshield prior to cover for this same reason.

[d.grimm]

John,
No weight and balance yet, not quite done.
Dave

[Steve Pierce]

From my Clyde Smith notes.

Vertical stabilizer should point 1 1/2" left of the middle of fuselage at windshield.

[cubdriver2]

There's another cool thing that you can do to a Vag to give it flaps for slow flight, when you sit in the seat the ailerons cables come together behind your head just below the headliner, if you remove the 3" metal connecting link and replace it with a spring and a safety cable that's 1" longer then the spring when you want flaperons all you need to do is bungee the two control sticks together so they pull the top of the sticks closer together and the spring will stretch and both ailerons will droop an 1 1/2" or so and you will still have 2/3 of your aileron travel and a poormans flap setup. Glenn

[BrettL]

From my Clyde Smith notes. Vertical stabilizer should point 1 1/2" left of the middle of fuselage at windshield.

Steve,

Any idea if that note was in general, or for a specific model? I would think the offset might need to be more for the higher HP engines. The drawings appear to suggest that there was NO offset designed into the vertical stablizer on the Vagabonds. Any offset would then be the result of a twist in the vertical stabilizer as the bottom mounts appear to be directly aligned with the longitudinal axis.

Brett

[challenger_i]

How about placing washers between the motor mount, and firewall, on the left side of the mount? This would give right thrust, and the effect would increase, and decrease, with the amount of power used. No major modifications, no "tweeking" of the airframe, no moving parts.

[challenger_i]

**********

[rideandfly]

I would apply a moderate force to the top leading edge of the verticle fin to the left. You will be amazed. Just look at the fabric as you do it and you won't go to far.

Steve,

Appreciate the info! My Vag's right wing is heavy, so will adjust opposite direction.

Thanks,

Bill

[Steve Pierce]

Rig the wings first by shortening the rear strut on the heavy wing before doing anything to the fin.

[rideandfly]

Rig the wings first by shortening the rear strut on the heavy wing before doing anything to the fin.

Will do, Thanks again!

Bill

[tnowak]

After my fuselage recover two years ago, it took 5 attempts at adjusting my struts to get my Vag flying S&L and hands off.
My suggestion is to only make strut fork end adjustments 1/2 - 1 thread at a time and then fly after to see the effect of adjustments....
TonyN

[rideandfly]

After my fuselage recover two years ago, it took 5 attempts at adjusting my struts to get my Vag flying S&L and hands off.
My suggestion is to only make strut fork end adjustments 1/2 - 1 thread at a time and then fly after to see the effect of adjustments....
TonyN

Tony,

Appreciate hearing your input. Will do so accordingly.

Bill

[Steve Pierce]

I have found that getting the outboard aileron bay ribs on each wing the same with a digital level gets you real close right out of the box.

[rideandfly]

OK, y'all have given me several ways to approach this issue for annual during the next month.

THANKS!

Bill