Trim and rigging?

I guess all -4 have a trim tab or wedge on the LHS of the fin to counteract the torque? I am nearly there wrt size, so the ball is central in the cruise, but was slightly surprised how much right foot was still needed for takeoff. Is this because of the slow airflow? Is that normal?

Once I have the rudder sorted I will work on the ailerons. Should I be able to get the -4 to be roll stable at all power & speed settings, or will it always fall away one way or the other except at the speed for which I get neutral ailerons. I guess I am asking, if when one corrects a heavy wing, is it being corrected for one speed or across the range? Unlike the rudder across the range seems logical.

At the moment the left wing feels slightly heavy with the ball in the centre, but the stall is not really biased. Perhaps just a little to the left but I put that down to engine torque.

Thanks.

These boots are made for...

Steve,

Right rudder on takeoff if definitely normal in the RV4, the Rocket is much more pronounced! It took me several months to finally get my rudder trim tab (non wedgie type) set for 170 mph cruise with my 150HP RV4. Then of course later, I re-engined her and had to re-set it after 10 years.
One RV4 builder I met offset his rudder 1 degree when he built it. This perfectly eliminated the need for a trim tab, but like all RV4's it changes with speed increase/decrease. I like the Rockets electric rudder trim tab, but the RV4 doesn't need it.

So, how do you like it so far?

Smokey

Foot full...

I kept reading about how RVs need a "Foot full" of right rudder on takeoff. I thought this was exaggerrated. So, one day I started easing off the right rudder on climbout and I almost did a helicopter,minus the tailrotor . It's just a matter of a lot of power(torque/PFactor) pushing on a very light small airframe. It's great ain't it .

As far as ailerons go, you should be able to balance them but only when the tanks are evenly full. I find it is very sensitive to fuel imbalance. At one point, I considered aileron trim. But I find that when I feel the stick pushing one way or the other, I am immediately reminded to check the fuel. I actually like the reminder now.

Congrats on your airplane. You did a great job. Now enjoy flying it.

John

Steve, when I first flew my 4, in cruise it was about 1/4 ball out, I also ran out of nose down trim. I bit the bullet, moved the Vertical Stab to the left 3/8 of an inch, I also moved the Horizontal stab up 3/8. For some reason my caveman calculations worked out and it flew straight at cruise, no need for the wedgies.

I agree with John, if you are sure that the tanks are equal and you still have a heavy wing, just use the trailing edge trick, it works. I also found that the heavy wing reminded me to check fuel.

Thanks for answering my mail, I'm still jealous.

Randy

There is a chance you built a slight amount of twist in your wings so don't be surprised if the won't stay in trim thru the whole speed range. I know a couple of OSH award winning airplanes with a slight twist in the wing, No big deal. In my 3 I picked a speed range (180-190 mph ind) that I normally flew in and trimmed the surfaces for feet off, hands off at that speed. ymmv
tm

Twisted Sister...

Speaking of rigging, it's been awhile since I rigged my RV4 (1996). I'm helping a new RV4 builder in SA rig his RV4 with a slightly heavy right wing. As I remember, I squeezed the trailing edge of the heavy wing's aileron.
Correct?

Smokey
HR2 (lots of P-factor

Negative...

Squeezing the aileron trailing edge makes the aileron fly "up" thereby lowering that wing. You should squeeze the aileron on the "light" wing.

Straight as a die.......stunning....

So lots of test flying this week. Lots of minor items needed tweeking and the oil pressure was too high, but yesterday afternoon she was really starting to settle down.

I have now found a little wooden wedge which sits on the LHS of the rudder and that has about centralised the ball. I will live with that for a while to be sure that it is central at my cruise speed. Since I am still trying to keep power on the engine I havn't really found what my comfortable cruise settings are.

With the ball close enough to centre I started on the aileron. One popsicle stick taped to the underside of the RH aileron completely reversed the problem, so I reduced it to half a popsicle stick! Now she is perfect! I even trimmed her on finals and she flew down approach at 65mph with me just 'guarding' the controls for much of the way.

I will live with these bits just taped on for now to be sure I still think there can be no improvement in several weeks time. Then I will start squeezing ailerons.

smokyray said:

Steve, ....

So, how do you like it so far?

Smokey

Click to expand...

Well Smokey, being a restrained Brit I am not sure I have words to describe. IKON is so agile and responsive that she is quite unlike anything else I have ever flown. She makes the -9a I built and owned briefly look like great grandma. She is easier to land than my Supercub, though I suspect less forgiving. She also need little more landing distance if any. The ability to go up is awesome though I have done no climb tests yet. Perhaps what is so pleasing, particularly now all the controls are balanced is the precision.

I was up at 8000' 45F yesterday doing three way runs. 22" 2290rpm was pulling me along at 184mph. She certainly seemed to be covering the ground but I havn't worked out how much power a 160hp is putting out at those numbers so cant really compare with VANS numbers yet. It seemed pretty good to me.

Well my fun is stopped for a little. After I refueled to put her to bed for the night the Skytec made an awful grinding noise. I thought this did not happen with p-mags!

Back to the future...

Brilliant Steve! I knew you would find your new 180 MPH Super Cub a perfect personal airplane. When I saw my first RV4 in a magazine in 86', that was my goal, a 180MPH Scout/Super Cub. I think the RV4 is that and much more.

Currently my HR2 is apart for inspection and a new Vetterman Exhaust, so I borrowed RV4Bill's RV4 to visit my Mum for her Birthday yesterday. 160HP, Sterba wood prop, 940 lbs. Jumped out of my strip in about the same distance as the Rocket, 1500 fpm climb, 155-160 knots all the way, burned 16 gallons to go 300NM. Can't be beat...

Glad you're having fun, will we see the Supercub on Barnstormers soon?

Smokey

PS: Thanks Mel for the Aileron tip, over 40 brain cells are gold!