Rudder trim issue on my Drifter

[Justin Hawkins]

Hi all. I'm hoping you can set me straight on an issue I'm having with my Drifter.

 

After transport and reassembly, my first few flights were great. I did notice, however, that the rudder required slight left pressure on takeoff and even a bit in cruise flight. This is despite the rudder having a rather large trim tab bent sharply to the right (looking from the tail towards the nose).

 

After a rough backcountry landing, it required a lot of left rudder. I inspected the tail feathers and controls for damage. Found a clevis on the right rudder control horn to be wrapped / tangled a bit so I sorted that out and thought I'd fixed the issue. The next flight resulted in less right rudder being required, but still not perfect.

 

I added a bigger trim tab because when I look back at the tail in flight (not easy) it looks as though left rudder is being applied. I increase the size of the original trim tab by 2" on the top, bottom, and aft sections. I've not flown it since.

 

My concern is this: I see several Austflight Drifters in the picture thread that have no rudder trim tab. should I be suspecting a structural issue ? I've ordered a video inspection camera and I'll use it to inspect the remaining parts of the main tube that I couldn't access otherwise. Everything on the airframe seems straight and tight. No deformation of the floor pans or rivets anywhere. All tubes look straight and everything fits where it should.

 

Any suggestions ? Does anyone else here require a massive rudder trim tab ?

 

 

[fly_tornado]

no, never seen one with a trim tab. I have flown 3 drifters and they all required a left foot input on take offs but flew straight once airborne.

 

 

[facthunter]

If you require a larger than normal trim tab correction it would be worthwhile to check ALL rigging of the aircraft. The trim tab being as it is will slow you down but wil also cause inflight loads to increase and must change the control capability, in some way. It is "masking " a fault that would be better corrected. Nev

 

 

[Justin Hawkins]

Agreed. If everyone else is flying a drifter with no trim tab, I shouldn't need one. I think I'll remove it altogether and start inspecting more thouroughly.

 

 

[skyfox1]

Hi Justin mine flys great with out any trim tabs, check the drag bracing cables from the wings to the rear of the boom to make sure they are right tension, also check to see if the wings are square to the boom.

 

cheers Geoff

 

 

[Justin Hawkins]

Hi Justin mine flys great with out any trim tabs, check the drag bracing cables from the wings to the rear of the boom to make sure they are right tension, also check to see if the wings are square to the boom.cheers Geoff

What should the tension be ? I think mine may be a little loose.

 

 

[facthunter]

Check wing washout as well. (Trammel and a level, initially) Did you specify WB or SB?. Nev

 

 

[skyfox1]

What should the tension be ? I think mine may be a little loose.

They should be tight enough so there is no movement side to side with the wings there is no set tension in lbs that l know of but you should be able to flick it and make a dull twaning sound thats how it was explain to me by Wayne fisher over here as he is the drifter manufactor here.

make sure you measure the distance so each wing is equal distance

 

 

[Justin Hawkins]

I'll check that, but I bet they're definetly loose. Maybe I can just twist them after disconnecting one end. That should tighten em up equally.

 

I'll check that the wing is square with the main tube and that the washout is accurate also. It's a strut braced bird with a 582. Austflight manufactured.

 

 

[skyfox1]

I'll check that, but I bet they're definetly loose. Maybe I can just twist them after disconnecting one end. That should tighten em up equally.I'll check that the wing is square with the main tube and that the washout is accurate also. It's a strut braced bird with a 582. Austflight manufactured.

Hi Justin dont twist any more than five times thats about max.

 

 

[Tomo]

I've flown a couple of 582's with rudder trim. To me was not necessary.

 

Left rudder on take off is normal as the slip stream etc... is opposite than if it was a tractor type.

 

What is it like on glide, either engine idle or off, does it need any rudder to keep balanced then? Determines whether it's thrust line, or rigging issues.

 

 

[Tex]

They should be tight enough so there is no movement side to side with the wings there is no set tension in lbs that l know of but you should be able to flick it and make a dull twaning sound thats how it was explain to me by Wayne fisher over here as he is the drifter manufactor here.make sure you measure the distance so each wing is equal distance

Hate to disagree on this but I was told (by a few people) a little lose is fine (definitely no twang but no slack either)... these are for stopping the wing moving forward. Not sure it would effect trim on the tail?

I have seen many with rudder trim and plenty with out... take some pictures please Justin and I will have a look and compare those others I have seen. What about the cables? are the equal? They can stretch...

 

 

[skyfox1]

Hi Tex it is only a dull twang

 

 

[Tex]

E flat or F sharp?

 

Gotcha... yeh I guess a dull twang would be the right frequency.

 

 

[skyfox1]

Hi Tex mine are quite tight l was supprised when Wayne Fisher told me how tight they should be .

 

My mates were so loose the prop hit it and broke on take off it wasnt very nice to fly to get it back on the ground.

 

l have move mine back to the front bolt on the elevator it gives a lot more clearance from the prop.

 

 

[Tex]

I wonder if Wayne likes them slightly tighter for a reason, hard to guess for what tightness is, very subjective. I might take a measurement off the mid point of mine ...

 

oh yeh, that is very loose to be hitting the prop. What, both those wires broke?

 

 

[skyfox1]

Hi Tex only one wire broke the paddock was real rough the motor was moving a bit and the prop caught the wire.

 

 

[Guest Maj Millard]

Tex, My Austflight 582 WB definitly needed a trim tab on the rudder. If not, a bootfull of left rudder was required at takeoff. With the tab, no rudder was required at take-off (or very little)...............she flew fine in cruise with no rudder imput required then. It was a fast machine so I don't believe it caused much drag.........................Maj...

 

 

[David Isaac]

What about engine alignment ... a displaced thrust line would cause uneven thrust points on the tail right ... or wrong???

 

 

[Tex]

Hi Tex only one wire broke the paddock was real rough the motor was moving a bit and the prop caught the wire.

How did it fly? (or not)

 

 

[skyfox1]

How did it fly? (or not)

It did fly but not good it weather cocked all over the place and change the ailerons when the wing move the aileron push rod would alter, he landed ok .

 

 

[Guest Maj Millard]

Could well do David, the thing with the Drifter is that the prop thrust goes directly onto the tail so any defiencies there are more magnafied over those of a normal tractor engined aircraft.........................................Maj...

 

 

[David Isaac]

Thanks Ross,

 

Are the drifter engines typically offset like we do with tractor installations to counteract prop thrust?

 

 

[Guest Maj Millard]

Look I seem to recall the 582 Drifter that I had may have had some offset in the chromemoly engine mount, although I had to have a fixed rudder tab on mine for straight takeoffs. Wayne Fisher would be the one to ask there......................Maj...

 

 

[Tomo]

What about engine alignment ... a displaced thrust line would cause uneven thrust points on the tail right ... or wrong???

Very much so, hence my question in post #11