Aileron trim in an 8 or not?

All,
I have read some past threads where the need for aileron trim in a tandem was mentioned. However, I didn't see where a thread had been devoted to this topic. Also, it might be useful to get an update of opinions on whether ailreon trim is needed or not. So, a couple of questions...

Do you find that aileron trim is needed in an 8? Since fuel imbalance is the main cause of roll trim imbalance, please mention how often you switch tanks.

Will an autopilot have a problem with the trim imbalance if aileron trim is not installed?

BTW, the merits of electric trim and manual trim have been discussed extensively in the past. So, please limit the discussion here to trim yes or no (not electric or manual). Also, I am aware that individual preferences will play a role in whether each of us thinks aileron trim is necessary or not. I'd just like to hear those opinions.

Thanks in advance,

I vote yes.

Essential? No.

Very nice to have? Yes!

I generally switch tanks once an hour, and can feel the imbalance at that time. Since I generally fly long legs with the A/P on, I rarely notice it - the Tru Trak A/P handles an hour or more imbalance with no effort.

Note that the trim required for "wings level with no forces" changes with airspeed, so if you really don't like feeling an imbalance in roll, you'll be re-trimming in the pattern as you slow down.

Paul

I'd say usually no...

I've flown, from the front seat, 5 or 6 RV-8s. Of these, 1 has a significant, and 1 a minor, variation in "heavy wing" over a typical IAS range (with the slip ball held central). The others all had no heavy wing over the speed range - once the Aileron Squeeze process had been carried out if required.

We didn't like the interference with the controls of the Ailn Trim springs, and are lucky enough that over the speed range have never wished for Ailn Trim on our RV-8 in ~230hrs.

We both change Fuel Tanks as often as required by regular Fuel Checks, and would regard a 4L (~1 USG) imbalance as "unnecessary" i.e. if you see that imbalance, why not change tanks? In time terms, maybe every 15mins or so if required?

Andy & Ellie Hill
RV-8 G-HILZ

I agree with Paul. Not essential, but very, very handy. As fuel burns off and one wing gets heavy you'll be glad that you have it.

Deft Touch

flickroll said:

I agree with Paul. Not essential, but very, very handy......

Click to expand...

In level cruise, I like to fly with my hands resting on my lap, the fingertips of both hands lightly touching either side of the joystick just below the grip itself. I also prefer to keep the joystick oriented straight up and down at all times. By occasionally tweaking the 2 axis electric trim via the China Hat atop the Infinity grip, the airplane will maintain perfect trim balance despite differences in fuel quantity in the tanks.

To keep the stick perfectly vertical without aileron trim, I suppose you could work to maintain fuel tank levels within a few gallons of one another, but aileron trim sure makes keeping the stick positioned the way I want.....handy.

Put it in

Roll trim is *really* nice to have, IMHO. As others have mentioned, your RV won't stay perfectly laterally trimmed across a range of speeds due to a myriad of factors such as P-factor, airframe asymmetry, control rig, etc. If all you have is fuel balance to manage roll trim, you'll constantly be busy working to get it right. In a plane like a Piper Cherokee, which is as stable as my living room couch, its not a big deal. But in the RV you'll find the plane is much more sensitive to external factors and won't stay exactly trimmed like the standard factory sleds will.

You're building a $90k airplane, so go ahead and spend another .2 percent and put the trim in. Its one of those things you'll use on every flight.

I vote YES. Worth it.

Critical? No. But if you travel at all, its worth what ever effort it takes to install. Seems like I tweek it every time I fly. Its either that, or, as suggested above, swap fuel more often than I want. And there are times when I needed to drain one tank pretty low. Having the ability to trim level sure salvaged the fun.

Putting it into perspective. Having flown for 25 years another aircraft with no aileron trim, I can tell you having it now makes the the flight that much nicer. If for no other reason than I no longer have to endure with exasperation the fact that one wing is a foot lower than the other and I have to hold a little rudder to compensate.

Best case, you install it and hardly use it.

Worse case, you do not install it, and 5 years from now slap yourself thinking jeeze...it would have been SO easy back then.

Aileron Trim??? Of course!

Can the RV-8 get out of trim? Yes it can. Should a pilot keep his aircraft "In trim" ??? Yes he should!

This is more a question of how you fly. If you instructed in the T-38 Talon for seven years like I did, you kept the aircraft in trim or faced the IP's fury! If you flew the Boeing 727 like I did for twenty three years, you always keep that wonderful airliner in perfect trim. Sure, the autopilot would over-power an out of trim aircraft, but it was a point of pride to keep the old three holer in trim. Well trimmed, the 727 would stay just where you left her as you reached into your kit bag to pull out an approach plate.

Like always trying for a grease job landing, professional pride was all the motivation you needed to fly the aircraft the best you could, and a professional pilot always keeps his aircraft in perfect trim.

Aileron trim? Of course!