Notes on Forming Patrol Wing Ribs (Plus Side-Bar On Rib Fit to Spars)

[sjt]

Bob recommends gluing mylar to 032. The mylar has parallel lines representing spars.
I used a table saw to cut mdf with parallel sides that were 32 -0.032 (patrol spar center line is 32 inches apart).
I then layed mylar on top of parallel side mdf.
The parallel lines can be lined up and over the parallel sides of the mdf .
They should be exact match.

Drill the tooling holes to forever match the mylar template with the mdf form.

I would recommend the tooling holes to be a little distance away from spar. I am trying to make sure there are no future issues with rivet to edge distances.
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I use the word parallel to emphasize how the parallel sides are of use during assembly


image_11022.jpg Those parallel sides are at right angles to the table during the assembly phase.


Rough mark the top and bottom of the airfoil. Use a jig saw to cut close to the edge. Routers only can take off a little at a time.

After routing - the mdf form has two parallel sides that are exact, and two routed sides that follow the mylar - aluminum template.

I even made mdf forms that had notches for the flutes.
In the picture below form block 3 has two dowel pins holding aluminum horizontally. The rubber holds aluminum down.
Using a wood dowel flutes can be made. The assembly is held firm with the press.

LIke Spruceforest above a lever can be used to make sure flanges are 90 degrees.

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Fluting pliers will work. You will find that the first rib will take an hour to flute. Once you get the hang of it , it will only take two minutes.



Consider investing in a company that makes mdf:

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[geraldmorrissey]

Does my heart good to see scratch building skills being passed on. On other hombuilding sites I visit, old timers complain that scratch building is dead and gone. Not among the Bearhawkers.
Gerry

[LBayliff]

I'm just starting a Patrol scratch build and am planning my manufacturing process for the wing components. I have a stupid question regarding bend dimensions on the wing rib flanges. What are the finished dimensions on the bent flanges meant to be?

On drawing 3 Bob specifies 9/16" flanges bent at 90 degrees however, in the booklet he recommends offsetting the rib form profile by 9/16" from the form block to draw the flat pattern for the ribs. In this case, the bent flanges would be slightly less than 9/16" due to the material consumed in the bend. Furthermore, I don't see bend radius specified for the rib flanges, although I would assume it would be the same as that of the spars at 0.1".

Thanks for posting your notes and Youtube videos of your build! They've been a great resource.

-Lane

[sjt]

I found this youtube video:

https://www.youtube.com/watch?v=h9fxo95D4Ik

a number 7 drill has about the right radius.


anyways the radius chamfer is a short cut , a square edge is longer distance.

If anything, the flange would be the tiny bit longer then 9/16 if you use the washer trick.

[sjt]

The question we all get stuck on is :

Are you supposed to cut the master template on the inside or the outside of the line.

The answer is neither . It is the middle of the line.


Also I like the spray on 77 for attaching the mylar to a piece of 032.
77.jpg

I cut to the outside of the line and slowly file to the middle of the line. You must leave some of the line.
Others might do it differently.

I also am very fond of 1 inch mdf as compared to the 3/4 inch stuff



As a rule we all start out with O.C.D. You have to remember we are building the wing with a plastic mallet.

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