bbellfly

My Feedback: (2)

I asked this question in the 3D forum. Please forgive me if you've already read it there. I'd like some other opinions.

(From the other forum, I got a suggestion to bow the fuselage enough to true it up, then reheat the covering and see if that will hold. If this doesn't work, I'd like more answers to the questions below.)

Thanks


I am assembling a 40 size Hangar 9 Twist. While the horizontal stab is centered in the fuselage, the measurement between the wings outside rear edge and the horizontal stabs out side rear edge is off by 3/8 inch from one side to the other. The fuselage is the problem, it's not quite straight. I've checked the distance from fuselage to out side wing edge on both sides, it is the same. The problem is the fuselage appears to be slightly bowed.

OK, now for my question.

Measuring this distance squares the horizontal stab to the wing.

Would it be preferred:

A) to square the horizontal stab to the wing?
B) to square the horizontal stab to the fuselage?
C) to split the difference between the two?


Thanks
bbell

BMatthews

If the horizontal is skewed by up to 2 or 3 degrees it won't matter enough to notice. But it would look terrible. You may want to just adjust it for a bit of skew but not too much up to the point that the misalignment isn't too noticable.

The fin mounting should be altered to sit parallel to the wing's center line. Or if this is a profile fuselage then I'd be worried about the effect of the added "camber" of the curved fuselage on the knife edge or just for general flying. If it's a built up fuselage the effect won't be as noticable but it would still be there.

aresti1963

I'd be more worried regarding the fin alignment than the tailplane. Although, as BMathews has said, the tailplane will look out of line, it wont have as much detrimental effect as the fin will. You could trim the fin with rudder correction, but this will only be a constant at one particular airspeed. In other words, the plane will be crabbing or yawing constantly whilst flying. If I were you, and I'd not got too far into the build, I'd be taking this plane back to where I'd got it from. However......... normally the conditions of guarantee state that you are responsible 'after' you begin the build.

MOJO65-9or10

Call Hanger 9 and tell them about it. The last 2 ARF's I've bought had to get new wings which were easy to get replaced when I sent in photos of the problems. These were not with hanger 9 but I bet they are not that hard to work with.

Dave

bbellfly

My Feedback: (2)

Thanks guys....

I looked at all the ideas given. The solution I have choosen. I lightly sanded inside the fuselage opening for the harizontal stab. On the high side I sanded the bottom. On the low side, I sanded on the top. Just enough to alow aliginment. When epoxing in place, I place some thin wedges of balsa. Don't get the impression there was alot of movement, it was only enough to allow aligiment. The tips of tooth picks would barely fit. I used enough epoxy to completely saturate all peices, then wiped down the amount that oosed out.


Thanks again for all your thouhgts.
bbell

seanychen

My Feedback: (4)

You know, I can't help but notice how suitable this issue is to the name of the plane

But as to the preference, it matters to the flight if the stab is non-parallel to the wing: elevator input will cause the plane to yaw a little.

As between the stab and the fuse, it doesn't really matter. But you might want to check the perpendicularity between the stab and the vertical fin. If it's not 90 deg, rudder input will cause a little pitch.

Sounds like you have fixed it the right way. Instruction usually tells you to fix the misalignment this way.