My Fokker DVII Project

[Maxim08]

Jeff,
I will be meeting up with GWP in a couple of days and will discuss with him.
More holes, lighter aircraft??
Regards,
John

[Jeff Brooks]

Originally Posted by Maxim08

Jeff,
I will be meeting up with GWP in a couple of days and will discuss with him.
More holes, lighter aircraft??
Regards,
John

I suspect the effected holes will just be a little larger in places.

[Der Grüne Flieger]

Jeff,

If the holes are only a bit off, we might also be able to just oversize all the holes to gain the necessary clearance. I know a way to do it without too much trouble.

Phil

[Jeff Brooks]

I spent last night at work plotting the hole positions as best I could. When I got home, Jim Kiger sent me an email that he had done the same thing. We came up with pretty much the same positions. I still haven't worked out the vertical portion of this equation. Jim also mentioned that the holes were supposed to be about 7mm larger anyway, so that will help correct any errors.
Once the wing is assembled and the wire in place, I will measure the placement of the wire relative to where the center of the holes should be. I will post the results here.

P.S. Phil, I got the last of #7 ribs done last night. today I start preparing #8 for assembly, if I can fit it in. My kids wanna go hiking in the park with your kids. Anna has already packed a lunch.

[greatwarpilot]

Thanks for the update Jeff. Did you take a look at those photos of original D.VII wing ribs when addressing the question of where the holes go for the bracing wires?

Cheers,

[gipsymoth236k]

Jeff,

The Fokker factory drawings show the internal brace wire rib holes to be of 25mm diameter. Their vertical and horizontal position dimensions are also given if you want them as well, but then again, these are for two of the top wing ribs only.

Regards, Gary Sewall

[Jeff Brooks]

Gary,
I don't have the Fokker wing drawings, but I do have the Charles Cash Drawings, and they show 32mm holes :


Any chance you could post a piece of the original Fokker wing drawings? I would love to get a copy of your original wing drawings ... are they available?

[Der Grüne Flieger]

Jeff,

I had a thought this morning to speed up the assembly process. Did you consider to glue the capstrip to the nose cap as a seperate off line process? IF we did this and it didn't make it harder to do the rest of the assembly operations the advantages would be as follows;

1) The cap strip would be better seated in the nose cap because you would not be exposing it to the additional bending stresses of jig while you are trying to glue it. Basically, jam it in with glue and clamp it.

2) You can also clamp it easier as the rib webbing will not be in the way.

3) If you use a preglued cap strip and nose cap, you will have less clamping as the rib comes out of the jig. You only need to clamp the trailing edge. Less clamps per rib equals more ribs to be done at one sitting.

4) You will be faster in making each rib as some of the more difficult positioning and gluing will be already done.

The only problem I can see is that it may be difficult to get the glued capstrip and nose cap into the jig. I am not sure how strong the assembly would be and if it could take a lot of handling prior to being fit into the jig.

What do you think??

P

[Jeff Brooks]

Hi all,

I had been working on the problem of the hole placement on the ribs for the bracing wire. I took the jigs and used them as a template to draw out the profile of the wing. I aligned them along the two places that do not change on the spars: the top rear of the front spar, and the top front of the rear spar. These are the two straight edges on the spars. I figured out where the wires originate, and drew the lines accordingly. I was able to plot both the vertical & horizontal alignment of the holes. I have drawn this out on graph paper, neat stuff ... the lines on the paper are supposed to disappear when scanned. I will scan this drawing and post it later.

As I was doing this, I found something else ... the measurements of the spar drawings don't match up with the openings on the rib drawings.

The drawing of the spar on the Replicraft drawings match the lower wing drawing on the Cash drawings, while the rib profiles that Cash provides are drawn only slightly different from the Replicraft drawings. The Replicraft drawings show a max height of 181mm, while the cash show 185mm. The method for drawing these are different too. On the Cash drawings, there is a top reference line, and a bottom reference line with 185mm between them ... there is no way to mis interpret them. The Replicraft drawings use a method where there is only one reference line and both the top and bottom numbers work off the same reference line. Both systems work well ... but at first I wasn't sure if the measurement of the top part of the rib begin at the reference line, or start where the bottom measurement ends. I had to look this up in another book, to be sure that both numbers start at the reference line. The Replicraft method is the method is the methoid used by NACA.

Here is a picture of the problem ...



Now I am scrambling to figure out the changes in the spar drwings!

[franzkait]

Cash used the fokker wing drawings , so it is the same .