Nose rib sizes .....

[fairchild]

Have been studying the plans to see the lengths of the tails (the back where the attach angle fits on) - as it appears that there are 3 different lengths. I need to see how many of which.
So I am studying the plans--- on page 5B. Im looking at the drawings of the upper and lower front side cap strips. I THINK I understand the plan there...... but what isnt clear are
the stiffeners which the rib attach angles attach to. In the middle left drawing--- it shows the top of the stiffener even with the lower layer..... and it appears that the lower end of the
stiffener is ON TOP of the lower cat strip...... how can this be since the stiffener is 1/8 and the lower cap strip is 1/8 there. Here is a picture of the plan with the question marked up.
Maybe I am not so good at reading blueprints.... (this is a Bravo version plan )
Tim

[Startin22]

What you can't see in the drawing is that there is a 1/8" spacer bar underneath the one that is shown. There will be two spacers in those locations making those ribs 1/4" short.

[fairchild]

OK---- so there is 2 thicknesses of catstrip in the top and only 1 on the bottom..... so the outer spacer bar overlaps the bottom cap strip ..... and the hidden one below it
just holds it up flush with the upper cap strip. Ok that makes sense now---
So I guess that anywhere the upper and lower cap strips are different heights-- there will be an extra spacer to bring it out even with the taller of the two..........

It would be nice to see a 3-D view of the spar in solidworks so I could rotate it around and see it better. Maybe have it translucent and have the layers different colors ! :-)
Thanks Star ! Dont like guessing when doing something as important as the spar !

Tim

[fairchild]

In case anyone else needs the same data---- i sent Mark an E-Mail to see if he knew the exact height of the factory nose ribs at the rear where it butts up against
the spar web. If I can get their measurement -- that should tell me if their spar webs will fit my nose ribs.
FYI--- my rib height is 220mm (not trimmed for length yet) and the rib length along the rib centerline is 335 mm.

Tim

[jaredyates]

I have not scratch built a wing, but my impression is that you're going to need some very accurate measuring to make this work, perhaps more accurate than it is reasonable to do.

[Glenn Patterson]

You have been given some good advice here about buying 3rd party spars and having them fit the homebuilt ribs. If you are committing to building the wing then it is a full on commitment with no soft shoeing to build a set. Purchase the spars and then move forward with confidence. No point in putting off buying the spars as they are necessary to build the wing anyways. Nothing on Mark but everyone measures different. We built our ribs and used MDF templates cut from a spare wing form to form the spars to our wing. Everyone builds different and cuts on the line, leaves the line and so your ribs may be perfect but not for the purchased spars. Point is never mind the dollars but the hundreds of hours invested in the ribs are a waste if the ribs don't fit or you are off building spars to match. It is simple to trim the ribs to length as they are installed and everyone fits perfect. We touched up parts with the Stewarts epoxy primer and a foam brush. Keep some in a jar and a shake it is always ready to use. Look at the drawings and use a system like make a chart listing the ribs with columns of front and rear spar. Note at each rib if it needs to be adjusted for length on either end.

Best advice that I have read that speaks to getting it done. "Sometimes I need to get out of my own way to get it done." It is true. I had a basement to waterproof last summer so I took that advice. I got my materials and went at it head on. Hired a contractor for the excavation & fill. I broke out 12 pick up loads of concrete from old foundations. Several trailer loads of trees, moved tons of stone and dirt with a shovel & got it done. Sometimes worrying the details to hold up the work is counter productive. There are hundreds of hours forming ribs and getting the lengths if it is really important can be determined along the way.

[Ray Strickland]

I once read a proverb that was attributed to an old-timer airplane builder: “It’s an airplane, not a a Swiss watch, just build the thing!” Don’t sweat a small difference in the height of your ribs compared to factory spars. Just make sure that on assembly the ribs match the contour of the spars at the top where the aerodynamic characteristics of the airfoil is most important. If the spars are a little taller than your ribs you can add a short (2 or 3 inch) doubler to the bottom of each rib to make it match the spar height where the two meet. Or, if the spars are not as tall as the ribs, just add a spanwise doubler along the bottom of the spars making them thick enough to match the contour of the ribs. Your airplane will never know the difference. Piece of cake. Done. Move on.

[fairchild]

As careful as anyone can be--- there is going to be some variance in dimensions-- as you say -everybody measures different-- a pencil line width plus or minus----
I think the easiest approach is to make my ribs and then make the spar webs to fit the ribs. I think the chances of the factory rib fitting to my liking are less than 50-50.
There may be a brake I can use but I may have to tweak its adjustments some to get it bending evenly the full length. I know that i want it correct the first time-- so I think
I have to make my spar webs.
Maybe the guy with the brake might even sell it to me--- I havnt asked yet.... that would be ideal !
Tim

[Glenn Patterson]

Hi Tim,
Everyone has to go with what works for them and it is clear that you want to get it done. This is one method that may work for you if purchasing the spars is less trouble for you. You have one rib. If you bought the spars then you could take a pieces of 6 inch wide aluminum to form the rib ends that fit to the spar(s). If it is fat then you could adjust your hammer forms slightly and be assured a great fit. The bottom is pretty flat so it is fairly easy to massage the form so that the skin goes smooth from middle ribs over the spar and over the front rib. It also would allow you to adjust the rib width so that you can decide if you want to joggle or not joggle the ribs to fit between the flanges. Our rib flanges matched the spar flange so we had to joggle. About the same time builders were not joggling and getting a good wing form by adjusting where they put the rivet on the ribs so it does not pull down a valley.
We had a HVAC shop owner help us form our ribs on his brake. Then an aircraft maintenance shop let us have free access to their shear and brakes. We have been lucky in that people are willing to work with us to build an airplane. The novelty of building and airplane has them interested and keen to help. If you are using an unknown brake take some long pieces to bend a long scrap & check it for straight. We had to do a couple adjustments to get the HVAC brake straight.
Glenn

[geraldmorrissey]

Trim nose ribs on installation.
Cheers
Gerry
Patrol #30 Wings