Shop Layout and Hanging Wings

[Archer39J]

Yeah, consistency is the key for sure. I'm seeing about a tenth of an inch at 30 ft, so says the tech sheets. Remember this would just be for alignment of the fuselage, not across the entire wing span. Putting it in one spot and not moving it would be necessary. Regardless, establishing a datum of sufficient precision is surely not an insurmountable task.

That said it could also be possible to fit the wings under my loft if the fuse weren't on gear. Anyone do that before?



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[marcusofcotton]

Water in a tube can give a very fine line to measure to. Laser lines are not as fine, at least the 2 I have are not. A little imprecision here, a little there and eventually you have a significant error.

X2 on the water level vs laser

[jim.mclaughlin924]

I finished my wings first. The first thing I did with my QB fuse was to set it on the floor and shimmed it up level. I did my wing attachment and built the struts. I think it worked well with everything at eye level.

[Archer39J]

I finished my wings first. The first thing I did with my QB fuse was to set it on the floor and shimmed it up level. I did my wing attachment and built the struts. I think it worked well with everything at eye level.

Thanks for sharing, I think this is the route I'll be taking when the time comes.

[swpilot3]

I like the idea of hanging the wings with the fuse set on the floor at eye level!

This sounds like it’s been beat to death, but here’s my two cents since I just hung and drilled my wings. I would not chance hanging only one wing at a time. After seeing how the process goes, there are too many factors in play.

The critical thing is that the two wings are the same in all measurements. This is so much easier to set and verify with both wings on the plane at the same time.

[Archer39J]

Well I certainly appreciate the discussion and patience in helping me understand something so critical.

[Glenn Patterson]

I read this item and could not resist a comment on our wing install. Not that it is that much different than what others have done but there may be a point that may help someone

We leveled the fuselage left to right and suspended the wings between scaffold frames. We used blocking to keep the fuselage level. Adjusted the elevation and wing angles with ratchet straps so the scaffold frames held the weight. I own an automatic survey level but a person can get good accuracy w / the water level. We checked that the attach holes were at the same height with the water level and the auto level. I think that was the main reason we parked the auto level for most of the process. We compared the water level readings against the auto level and there was no visible difference. The difference between auto & water levels is hair splitting over the distance of a wing. The mark on the tape measure is several times the thickness of the optical level cross hair. It is like using a microscope at close range. The water level has good accuracy and is easy to move about especially to check level on both sides of the airplane. It is important to have no air in the water tube, add some food color for contrast & a few drops of dish soap to reduce surface tension on the water. A person has to let the level be still and always read it the same way. Checked the cross fuselage level with the water & auto level to double check, We set a working level references on both sides of the fuselage so we could check that the fuselage stayed level as work progressed. We repeated the same method of hanging the wing on the other side all the while constantly checking all the elevations with the water level. This method keeps the weight of both wings supported with the scaffold frames. The wing weight is not in play on the fuselage to have much effect on the transverse level. The end of wing references were within an 1/8th of an inch of one another to the tail post. We checked the elevations and worked to put the struts in. A person cannot check measurements & level often enough. If the wing is within no recognizable difference over 14ft that is a good tolerance.

I have surveyed large pulp & paper machines for roll alignment with equipment that can read in one thousand increments for square and a level that can read at 30 ft to ten thousandths for elevation. I have surveyed for the installation of a lot of equipment over time. I borrowed a precision automatic level from work to put reference marks around the house for the installation of concrete forms that had 1/16"/ft slope.120 ft of forms were constructed & leveled with a water level against the reference elevations & a measuring tape. I borrowed the level again to check the forms and found them to be spot on. I have a high degree of confidence to take the readings with a water level within the radius of the wings.

Our fuselage is dead straight within a fine line from end to end. We installed the wing attach fittings measuring every which way to Sunday. Used threaded rod to hold the attach point distances. We had centerline references on the fuselage from its construction that we used to measure and set them attach points parallel. We double checked that the measurements on both sides we the same distance from the tailpost reference. We used 20 lb black dacron fishing line with a 10lb weight for our free space centerline by stretching the line using references. It is as thin as a fine pencil line

We often used a fine line tensioned with a 10lb weight for a working centerline reference in the course of our build similar to the high tension piano wire center lines used by the by equipment erectors. The jig pin holes in the wings were set with a tensioned string line using a bead that just cleared the hole. When the light all around the bead was the same then the rib was located. The jig pin holes appear as one hole through all the ribs. The wing construction was done by setting the spars with the automatic level. We kept a taught string line set at 40mm at both ends above the spar. We constantly checked that the string was 40mm off the spar along the length of the main spar with a ruler. If there was sag then added support to keep the main spar level to the string. The rear spar was an easy check with a tape measure to verify if it was parallel or needed an elevation adjustment. A lot can be accomplished with simple tools like a water level and a very tight string. The point is that if person uses a care and sound measurement principles then it will be straight, level & square.