Rudder "trim" tab - like it or not?

[Hottshot]

having flown 2 with out and 1 with I prefer with out but wouldn't flinch at either

[MauleMechanic]

The servo tab actually has some purposes.
Many other light aircraft have a more intrusive interconnect directly from aileron to rudder.
Maule built 6 M7 in 1984/5 with bungee spring direct interconnect but we didnt like it and the servo tab was back in service.
One may notice how spin resistant the Maule is. Try fully cross controlled at 45 mph at stall attitude in any other aircraft.
Try setting up a banked turn with aileron and rudder then neutralizing both then with hands and feet off take all the pictures you want of the circled target with no deviation of the airplane.
Re -7 flaps, the most speed increase I have seen is 6mph, I got 4mph in an MXT demo yesterday at 100 F and 2500ft. Depends on temp alt and cg position whether you will gain or lose speed.
The BIG advantage of the -7 is in the landings for both taildraggers and especially trigears.

I use to fly Maule N42269, MT-7-235 for the Georgia Forestry Commission. It was nice to do this, with windows open too, while circling a wild fire for 8 hours (fuel stops of course). However, aux tank fuel management was a must!

[Mountain Doctor]

However, aux tank fuel management was a must!

And a wide mouthed bottle....

[MauleMechanic]

However, aux tank fuel management was a must!

And a wide mouthed bottle....

I played bomber pilot a many a time with a full gatorade bottle!!!!

[Ralph Mailloux]

Jeremy -

Could you please give a little more information about the Tailspring installation on the TriGear.

Do you have any pictures of one installed, where can one be obtained, and is a 337 required?

I need to do the Vulcan Mind-Link on you so I can stop asking you endless technical questions!

Thank you...........................Rob

Rob,

Did you end up doing this?

[andy]

I wouldn't mourn the loss of the rudder servo tab, but it does make the Maule more spin resistant. Sometimes it's weird in a bank. I've gotten a cruise speed increase of 2 - 4 mph with the -7 degree flaps. My MX-7-180 is so draggy with the 8.50 tires and ABW HD gear legs that any reduction in drag at cruise is welcome for the fuel saving ($$$). I haven't tried to lower the flaps to -7 on landing since I'm short and it's a long reach down to that flap position while trying to see over the glare shield at what's ahead and apply max aft yoke while braking.

[MauleMechanic]

I did an annual on N660HB a few years ago while on floats sometime when it was exported back to the US from Germany. The servo tab was connected backwards which would create more adverse yaw rather than help prevent it.

[formerpacerdriver]

Last night I tried to fire up and fly down to the local maintenance shop. This little effort took all day, since I had to install skis following our foot of snow (ungroomed runway). The snow was followed by freezing rain, by the way. In addition ski install and working off the frozen covers, I had to preheat since it was about zero Deg. F.

When the engine was finally warm and skis install double-checked, I performed a pre-flight and noted the ailerons would only roll about halfway. Since it was now 3 PM and starting to get dark (64 deg. N. Latitude), I actually thought a moment whether I could fly with only half aileron control (Very bad idea, but it did cross my mind).

I checked all the ailerons themselves, inspection holes in the wings, took apart the baggage bulkhead to check cables in the floor, looked down the hole under the dash, and couldn't isolate the point of the sticking. Finally I pulled out the Maule manual and found the diagram for aileron controls, and of course, was reminded of the rudder trim tab interconnect. Sure enough, the tab cable was frozen at the ruder. Some well-placed heat and then Aircroil freed up the frozen cable housing.

So back to the original question - rudder trim tab or not? I would have not had trouble yesterday if I had no trim tab. Another thing I notice is that you fly feet-off-the-pedals at cruse but NOT at slow airspeeds, so my poor brain has trouble switching from passive to active control. Lastly, the M-6 seems to have less rudder contro than I'd like (in slips for instance), so removing/covering over the tab may help this.

I guess that I'd like to try a Maule without the trim tab, and see for myself.

[maules.com]

Dano, the tab on the rudder is Not a trim tab, it is a servo tab.
The yaw trim system is a spring bungee style pull influence on the right rudder pedal.

[aero101]

I have also found when lubing acft up here for winter months flying, to use graphite lube as it doesn't freeze like lots of the aerosol lubes do. They have small aerosol's of the graphite at NAPA, and the moisture used in can evaporates, leaving a dry lube that won't freeze under any conditions... Personally, I set my servo tab for hands off level flight and otherwise just leave it alone.

[MauleMechanic]

I have also found when lubing acft up here for winter months flying, to use graphite lube as it doesn't freeze like lots of the aerosol lubes do. They have small aerosol's of the graphite at NAPA, and the moisture used in can evaporates, leaving a dry lube that won't freeze under any conditions... Personally, I set my servo tab for hands off level flight and otherwise just leave it alone.

The servo tab can not be adjusted by the pilot. The cables are connected to the aileron cables above the pilot and passenger where the zipper is in the sides of the headliner.

The rudder trim is nothing more than a push pull cable connected to the copilot right rudder peddle.\ behind the copilot kick panel.

[aero101]

And that 'T' handle on end of that cable is the servo trim adjustment as the way it's all interconnected thru ailerons is not what you'd commonly call trim, and it does work slightly differently.

[pilot]

Jim, I'm pretty sure that no matter what you do to the t-handle on the rudder balance cable the ailerons will not be affected. The turn coordinator tab on the rudder is totally independent of the rudder controls or rudder position.

[MauleMechanic]

And that 'T' handle on end of that cable is the servo trim adjustment as the way it's all interconnected thru ailerons is not what you'd commonly call trim, and it does work slightly differently.

I am not sure I am following you here. The rudder peddles move the rudder. The ailerons move the servo tab on the rudder to aid in preventing adverse yaw in a turn and the T handle cable adjusts the amount of right rudder pressure in the same way the elevator trim relieves pitch presures and aileron trim relives bank pressures. The T handle is used to aid in the relief of right rudder pressures It either increases right rudder input from neutral or decreases right rudder input back to neutral. It does nothing for left rudder input. I use it for long climb outs to relieve pressure on my right leg. In level flight I use it to center up the ball using various cruise speeds, thus, if the airplane banks left or right with this set, you have a rigging problem or uneven fuel levels in the aux tanks. The purpose of the rudder trim is not to correct an improperly rigger airplane but to relieve right rudder pressure in a given attitude.

[aero101]

Yes, I understand what you're saying. You also need LH trim for power off descent too... For the difference check out your elev trim, you dial it in at tab, tab stays fixed at same location thru out the travel range, there is NO spring preload to overcome. This is not the case with the rudder, but if you want to call it rudder trim, rudder servo trim, or servo tab, they all do trim job but the servo trim also drives the ailerons with cables attached to aileron cables at wing root which are interconnected to rudder trim cables in tailcone... It's also not as effective as the straight trim. It will also tend to put you into a coordinated RH turn if you take hands off yoke with T pulled all the way out. Straight trim will turn you as well but would be a skidding turn. Proper terminology would be active servo trim tab, the servo part of equation driving ailerons... Or are ailerons driving rudder tab... It all depends upon how much preload against spring under boot cowl / upholstery RH fwd fuselage...

There are four major types of this trailing edge tab control.
( 1 ) An " active anti-servo " trim tab system : Anti-Servo Trim Tab This system of trim utilizes the "race ahead and help push it back" theory of trim. It does this by having the little trim tabs race ahead of the elevator in both directions of travel and aerodynamically force the elevator back to equilibrium. The linkage basically connects the trim tab to a fixed part of the airframe (or servo motor attached to the airframe). The way you get reversed travel is to push on a lever that is ahead of the trim tab's pivot point. From a trimmed position, if you bump the stick, this concept aggressively returns the aircraft to its former state of flying. In general, the tab's position is always up to offset the aerodynamic loads of the elevator. The tab travels farther up as the elevator travels up, and the tab travels down as the elevator travels down. Note: this is the most stable configuration you can come up with. The trim settings (once established) would neutralize elevator forces to the control stick for a very small range of elevator travel. Once the pilot exceeds this little range of neutral (low) forces, the stick loads would load up fast.
( 2 ) An " active " or " motor driven " trim tab system : Active Trim Tab This system of trim utilizes the "motorized bent metal plate" theory of trim. The little tabs are inert as the elevator goes up or down and do not actively assist in returning the elevator to equilibrium. The linkage connects an electric motor (or mechanical trim wheel cable) to the movable trim tab at a point that is aft of the trim tab's hinge point. In general, the tab's position is always up to offset the aerodynamic loads of the elevator. From a trimmed position, if you bump the stick, this concept neither hinders or helps return the aircraft to its former state of flying. Return to equilibrium is achieved by a longer period porpoise effect as the aircraft "seeks its own" based upon power and drag. This type of trim tab system is only slightly better than the " fixed " version in that the servo motor can adjust the tab positions and affect a trim condition for the aircraft. The trim settings (once established) would neutralize elevator forces to the control stick for a small range of elevator travel. Once the pilot exceeds this little range of neutral ( low ) forces, the stick loads would load up fast.
( 3 ) A " passive " or "un-powered" trim tab system : Same as above except that this is just a bent metal plate sticking out in the breeze. It would be the same as above when the servo motors fail. You bend the tab once and it is good for a small range of speeds and elevator settings. There is no pilot control of the pitch trim. Once the pilot exceeds this little range of neutral ( to low ) forces, the stick loads would load up fast.
( 4 ) An " active servo " trim tab system. Servo Trim Tab This system of trim utilizes the "push in the opposite direction and help the elevator to go" theory of trim. It does this by having the little trim tabs work opposite of the elevator and generate aerodynamic forces that aid in the elevators travel. The elevator is helped away from equilibrium. From a trimmed position, if you bump the stick, this system aggressively pulls the aircraft farther into the perturbed state. The linkage essentially connects the trim tabs to some fixed part of the airframe (or servomotor attached to the airframe) at a point that is aft of the trim tab's pivot point. In general, the tab's position is up if the elevator is down, neutral if the elevator is neutral and down if the elevator is up. The tabs travel up as the elevator travels down, and the tabs travel down as the elevator travels up. Stick forces imparted by the elevator would be neutral the whole time. Note : THIS IS AN AERODYNAMICALLY UNSTABLE CONDITION. This type of tab would be a great as a booster for ailerons or really big elevators that overpower the pilot’s best efforts. In effect, this type of trim system is "power steering".