Rigging

[Dick B in KY]

OK, need some input. My SS with 912ULS is in phase 1. During cruise, with the ball centered, equal fuel in the tanks, I am getting a "slight" roll to the left. Which lift strut needs adjusting and which way - in or out? Don't want to start chasing a bunch of stuff, when the plane flies great other than this.

Dick B

[Geowitz]

A slight roll to the left means you either have too much lift on the right wing or too little on the left. You want to either shorten your left back strut fitting to lower the trailing edge of the left wing to create more lift or you want to lengthen your back right strut fitting to decrease lift on the right wing. First though, before all else, I would recheck your wing washout angles to see if they already favor one side causing the slight roll. That way when you do adjust you are doing it in a way that will induce the least amount of drag while retaining close to symetrical washout between each side.

[SkyPirate]

Just a thought and every situtation/ location is different, a local builder that was in stage one , the DAR told him he could have someone ride right seat to have equal weight and also for the passenger to take notes concerning engine ops, etc, the co pilot in this case was also a cfi, if your DAR isnt as flexible you could put weight in the right seat

[jiott]

I had the same thing, a heavy left wing, in my first few flights. I agree with Geowitz about which struts to lengthen/shorten. I ended up doing 1 turn in or out on all four struts before it flew straight. As he suggested, I measured my washout angles first to make sure they were correct (they were). I suppose when I put a passenger in the right seat it will want to roll right a little, but I don't care because 95% of my flying will be solo.

Jim

[cgruby]

If I may, let me interject another thought process. Washin/washout (I can never remember which is which) is there for a purpose. We adjust the wing so the tips are twisted down to allow them to fly when the rest of the wing is at an angle of attack which causes them to stall. It is important to have the wings twisted such that when you stall, the aircraft does not roll in either direction but stalls straight ahead. Who of us wants to come in for a landing and just before we touch down, have one wing suddenly drop?

So the message here is to adjust washin/washout per the factory, then go and stall it. Does she stall straight ahead. or does it fall off on one wing (consistently)? I tend to lower the angle of attack on the falling wing, by twisting the tip further down, until it stops doing that. You do this by lengthening the aft strut only one half turn at a time.

But what about correcting for wing heaviness in cruising flight you say. You correct this with a tap on the aileron, or in this case the flaperon. All Cubs have them, all Stinsons have them, just about all airplanes have them (except the Kit Fox).

Cheers,

[Geowitz]

A good thing to consider if you can follow these steps. This kind of what I was referring to with respect to retaining symmetrical washout, but on a Kitfox you may have to adjust one differently if you want to fix the heavy wing(without using a trim tab). I am not aware of this really causing significant tip stall problems on a Kitfox though.

[jiott]

I would suggest talking to John McBean before you do anything-I did. There are definitely limits to how much adjusting you want to do. I agree 100% that after any adjustment you need to recheck the stall characteristics and make sure it stalls with wings reasonably level.

Jim

[neville]

Interesting discussion. I am also in Phase 1 testing and also have a heavy
left wing. I refer to the SS7 build manual and see: 1, level the A/C, 2
adjust the dihedral to one degree up by adjusting the rear spar lift strut, 3
adjust the washout to 1/2 in down at designated measuring point by adjusting front lift strut. So the it seems to me that if you change washout by adjusting the rear strut you are changing the dihedral. I read
the instructions as; use rear strut adjust for dihedral and front strut
for washout. To correct left wing down I found ( by measurement with digital level) that right wing did not have enough washout and the left wing had too much.

[Geowitz]

Weird... Every other discussion I have seen or heard notes using the front spar for dihedral and rear spar for washout. But, either way as long as the twist is correct and sweep is aligned it really shouldn't matter in the overall scheme of things. True, changing either will change the dihedral and washout at the same time because you are changing the overall average angle of attack.

[Geowitz]

So to say... from the horses mouth...


http://www.teamkitfox.com/Forums/sho...light=dihedral



"You are entering the "Test Pilot" stage. Be sure you are qualified and comfortable with making changes and test flying your aircraft.

Knowing that you are not the builder... I would suggest a reset... assume nothing.

Check the horizontal stabilizer for correct installation..
Set the wings back to the standard known condition and start from there.

Refer to your manual. 1 degree twist and 1 degree dihedral. Check length of the rod end thread.

From that point you can adjust either side.. we will typically decrease the angle of incidence first then increase on the opposite wing if needed. try to make changes equal.

For example.. We have a slight left turn.. or a heavy left wing as they say.

We have determined that we do not have a yaw issue that is causing the left turn.

We adjust the right wing rear lift strut rod end out 1 turn... record our change and pre-flight for a test flight. Decreased Twist (wash-out)

Not enough.. so now we'll adjust the left wing rear lift strut rod end in one turn.. record our change and pre-flight for a test flight. Increased Twist (wash-out)

Still not enough.. adjust the right wing front lift strut rod end in 1 turn... record our change and pre-flight for a test flight. Decreased Twist (wash-out)

Still not enough.. adjust the left wing front lift strut rod end out 1 turn... record our change and pre-flight for a test flight. Increased Twist (wash-out)

You may need to make a 1/2 turn or maybe a 1 1/2 turn all depends on the severity of the roll rate... "