TitleGarrison

No bird ever flew nonstop from New York to Tokyo, or raced 15 miles high at triple the speed of sound.                                                                                                   
  But birds do something else.
  They do not conquer the air; they romance it.
.”

  Peter Garrison

HoursAndCounting

Jur's RV7 Aircraft Factory
2917 hours
and counting
Some decisions in life are bare of any obvious logic

 

Today, I decided to matchdrill the F704 to the center fuselage bottom skin. What sounds like a simple task at first is in reality one of the most important in the construction of your RV-7. This is where the spacing between the F704 forward and aft bukhead gets fixed. As you know by now, this is where the wings mate to the fuselage. Too large of a gap and you will bend the bulkhead sides inwards when tightning the wing attach bolts ( a no-no ! ). Too small and you wouldn't even be able to insert the wing spar in the fuselage !. This may seem obvious to you know, but there are many many examples on the forums of people who end up with too thight slots between the F704 bulkheads. Some people have sanded on their main spars to be able to insert them ( an even bigger and absolute NO NO ! ).

All this, just to get your attention and make sure that you take your time when you start doing this.  This is one of those places where you measure at least 3 times before you move on.

 

The first step is easy. You only have the aft part of the F704 in place with clecoes and just have to matchdrill each predrilled hole to size. But... wait a sec... The manual doesn't talk about the forward bottom skin at this point. If you think about it, the forward skin will have to be matchdrilled too at some point. If you would just do the center fuselage bottom skin and F704 bulkheads now, the next step would be to deburr holes and dimple them. (no way you would be able to dimple the second row on the F704 later once the bottom skin is rivetted to the seat ribs. So, the bulkheads must be dimpled. This means that it become difficult to matchdrill in an already dimpled part later. That's why I pulled out the forward bottom skin now and clecoed it to the F704. The forward skin goes over the center fuselage bottom skin. I clecoed the whole thing together again and then matchdrilled the aft F704 row.That fixates the bulkhead, the center fuselage bottom skin and the front fuselage bottom skin.

Next I pulled out the spacers made earlier when assembling the F704 bulkhead. I made these spacers out of aluminum tube.

I didn't like the idea of wood as it is too sensitive to temperature and humidity changes. Also, I find would more difficult to set to exact size. And as I'm being anal again, i would like these spaces to be within few thousands of an inch.The spacers need to be 1 inch 7/16" or 1.438". In this case I'm using the thousands value on my caliper to be as accurate as possible. I remade one spacer as I found it too short. 1.438 is exactly the gauge of the wing spars. To make these spacers, I cut some aluminum tube, the straightened them with the vixen file. Next, I chucked the aluminum tube in my drill press. Then hold the vixen file flat on the drill press table on some would and gently press the tube against it. This way you take away thousands om an inch easily. Last, I brought it to final size by pressing the tube on some 400 grit sandpaper until I got somewhere between 1.438 and 1.440 inch.

Finally installed the forward side and put the spacers in place. I bought some bolts at Lowes earlier and sanded away a bit of the shaft so they go in without forcing. DO NOT USE THE FINAL BOLTS. They are very thight (and it's supposed to be like that).

After measuring multiple times, I also clecoed on the F704H center section side plates.

Then matchdrilled the foward side F704 row.

As a last step, I matchdrilled the side plates.

I realised I forgot to matchdrill the seat ribs to bagagge rib holes. Most are easy but the intersection show in this picture is quite tricky and will require you to get out the 12" drill with some bending in order to have access.

And here is finished work of the day. F704 matchdrilled.

How to use

Use the kit buttons in the top ribbon bar to see a chronological overview per sub section per kit. For the full chronological article list, see chronological build link in prelude menu here below. The easiest way to lookup information is by typing in some part numbers or keywords using the search option in the ribbon bar

 

Caution !

Some advice on reading my log for fellow builders !

In some articles, I made corrections at later date on the original article to rectify my own stupidities or faults. Read through the entire article if you intend to use my findings/experiences on your own project !

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Legal Mumbo-Jumbo

It’s possible (not likely) that I’m not as smart as I think I am. (Occasionally, I have moments when I know this to be true. Fortunately, the feeling passes quickly.) Although I have tried to make this information as accurate as I can, it is not only possible, but also quite likely, that erroneous and misguided information lurks within these pages. I cannot and do not warrant these pages to be error free and correct. Furthermore, I accept no liability for the use of this (mis)information. And, as many would say, your mileage may vary. If, after reading this, you are intent on proceeding, please be aware that the contents of this site are protected by copyright (copyright © 2011 and 2012). Nonetheless, you may copy this material subject to these two conditions: (1) any information used is for non-commercial purposes, and (2) the source of the material is properly credited. Of course, you may link to any page herein. At some articles, snippets of the plans from Vans are visible. These are for educational and illustrations purposes only and should never be used as plans for part construction or assembly as plans may have changed since the picture was taken and more important they are protected by Copyright by the Vans Aircraft Mothership company.

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