Fitting the Upper Longerons

[mlwynn]

Hi all,

I recently did the mating of the aft section with the mid and forward sections. At last, it is starting to look like an airplane. Once all the skins were clecoed on, it was time to drop in the upper longerons. I confess that I didn't bend them until now, as it made more sense to keep them safely stored.

At any rate, I bent per the plans and then put them in place. There is a certain funkyness to the fit that I can't quite figure out. In the aft section, bulkheads 808 to 812, the longeron is straight the and fit is perfect. The top of the longeron is slightly canted inward, following (I think( the shape of the skin. At the forward end, near the motor mount weldments, it is canted in even a little more, to fit with the weldments. The issue is in the middle where it runs by the center section F804 bulkheads. Their upper flange is horizontal (i.e. if you put a straightedge across them from one side to the other, the staightedge would be flush all the way across). The longeron is canted in and is not parallel to this. It also doesn't seem like it quite fits right at the bulkheads where the gear attach.

I'm trying to figure out if I should put a little twist on the longeron: outwards just forward of 808 and then back in at 804 or if it is really supposed to be completely straight in that dimension.

Can anyone share a little insight or experience?

Regards,

Michael Wynn
RV 8 Pre Punch Fuselage

 

[Guy Prevost]

Hi Michael,

I just went out and looked at my pre-punched fuselage. The longerons are near, but not quite level at the F-804 center section. The abgle is defined by the tabs on the F-804 parts. I would not try and put an extra twist in the longerons.

I think you'll find that they will find a happy place in the notches and tabs at the top of the center section. If the longerons are not fitting too well there, take a small block of wood, place it in the corner formed by the tabs of the F-804 center section and then clamp the "wood-F804tab-longeron" sandwich together in both directions before drilling the longeron. As you work from front to back things will just begin to fit.

Regards,

 

[Scott Hersha]

The upper longerons are supposed to slant in slightly, more so as you go forward starting at about the forward seat back support. The cockpit side rails that go on top of the longeron has a bend in it- 3/4" in from the outboard edge - to fit flush on both the longeron and the top bends in the 804 bulkheads. Just make sure the side on the longeron is flush with the inward curving forward side skin and it lays flat. You'll also have to make your gear tower web (with the 5 holes that you drill into the longeron) sit even with the apex on the longeron. This usually involves pulling inboard on the skin/longeron with some sort of racheting strap. Have you run out of clecoes yet? I've borrowed some from 3 different guys....the whole fuse is clecoed together...

 

[rvbuilder2002]

I am curious what all the RV-8 prepunch fuselage builders think about the kit and construction manual so far?

 

[Guy Prevost]

I am curious what all the RV-8 prepunch fuselage builders think about the kit and construction manual so far?

Overall, I'm really impressed. The new drawings are works of art. They're not "real" drawings in that they are typically not three view and don't have dimensions. They do a fantastic job of conveying how the Assembly goes together though (which is their intent). Most of them are 3D views both exploded and assembled.

The manual is very step-by-step. Generally the instructions are excellent and Van's has appeared appreciative when I have emailed them about mistakes in the instructions. They actually have me convinced that they will incorporate the corrections. One problem with the detailed instructions is that they can cause complacency. I've made several mistakes because something wasn't expressly called out in the instructions. The instructions are so complete, that I tend to turn off my brain periodically and follow them blindly. This always causes me grief.

As for the matched-hole parts--They just work. I put the whole fuse together, jig free and it's perfectly straight. I have had a few problems with missing parts, but Van's has been very good about sending them to me right away. It's also obvious that they didn't dry-fit an 8a fuse together. There are significantly more problems when I'm working on parts specific to the "a" model.

Guy

 

[Rick6a]

I am curious what all the RV-8 prepunch fuselage builders think about the kit and construction manual so far?

Scott,

I think the kit itself is impressive particularily as regards the matched hole technology. I've done sheet metal work most of my life and even McDonnell-Douglas didn't have that technology.....at least up to when I retired a few years ago. Another thing that impresses me is how (wing kit) butt joints are astoundingly close, yet positive clearance almost always occurs.
Technically, the airplane parts are so precise and a consequence...builder labor and skill is so reduced that I sometimes think I'm cheating.

The fuselage instruction manual however, leaves something to be desired although I am quick to add it is light years ahead of the RV-6A manual! Still, there are many spelling errors and I've reported at least one obvious descrepancy that will be addressed in future releases. I like the "bullet" point format yet given the many crucial differences between the -8 and 8A, I suspect less confusion would result if each model had its own manual instead of having to skip around and cull the relevant information that is applicable to your model from the common text. I suspect that is done as a cost saving measure but even French and Spanish instructions that are included in everything you buy these days are included in separate pages. Also, it wouldn't hurt to include at least some detail photographs....in color of course.

A friend of mine building a Zenith 601 is astonished at the comprehensiveness and quality of the kit parts, yet I do have to concede to his wry observation that the far simpler 601 design includes a builders manual that is a more detailed document and includes scores of photographs throughout its pages.

I'm picking nits here....on balance, I am pleased with the RV-8 fuselage kit. It is more than I expected...truly.