Fuselage skin questions

[JanRV6UK]

I have a few questions that I hope to get a few opinions on

I have started to skin my RV6 and a bit confused over the rived sizes –

1 – The front skin (bottom) My old blue prints show #3 rivets on both the firewall front flange (stainless) and the ¾ alu angle stiffener – I see that on later drawings – the rivets used on the ¾ is changed form to size # 4 (I understand this is due to experience with smoking rivets when #3 was used.

What about the 4 stiffener that are riveted to this skin ? #3 as per old drawing ? Or do later kits have #4 rivets here as well ?

The skin in .040 – Dimple or CS ?


2 – On the side skins – bulkhead F604 – It looks like the bottom rivets are # 4 (around the spar and above the spar – but then at the top – The drawing show #3. Why not use #4 all the way to the top longeron ? – Skin is .032 – So Dimple skin and CS frame sound like the way to go here.


3 – On the longeron – Up to F605 – the rivets looks to be #3 on a 1” spacing – Then from the F605 toward the front – it changes to #4 – with a 1 ½ spacing - Is my understanding correct ?

Appreciate comments ...

Jan

 

[Stevea]

Jan,

Here is how I built mine:

1. front bottom skin: #3 rivets on the firewall flange. #4 rivets on the firewall angle. #4 rivets on the four floor stiffener angles. #4 rivets on the bottom skin to F604. Dimple all holes in the .040 floor skin, countersink the angles.

2. side skin to F604: #4 universal rivets around the spar. #3 above the spar up to the longeron.

3. longeron up to F605: your interpretation is correct.

 

[WingsOnWheels]

Jan,

I agree with Steve 100% on points 2 and 3. For point 1 I also agree on using -3 for the firewall flange and -4 for the firewall angle. However, I suggest you stick with the plans and use -3 rivets for the floor stiffeners. The stiffeners are only 0.063 and coutersinking those for a -4 leaves the bare minimum or material. Add in the fact that you need to countersink a little deeper to accomodate the dimples in the floor skin and you are at or close to a knife edge on the angle. Sticking with the -3 rivet here will prevent these issues. If you are concerned about the smaller rivets, you can also tighten up the rivet spacing rather than switching to a larger rivet.

Jan,

Here is how I built mine:

1. front bottom skin: #3 rivets on the firewall flange. #4 rivets on the firewall angle. #4 rivets on the four floor stiffener angles. #4 rivets on the bottom skin to F604. Dimple all holes in the .040 floor skin, countersink the angles.

2. side skin to F604: #4 universal rivets around the spar. #3 above the spar up to the longeron.

3. longeron up to F605: your interpretation is correct.

 

[JanRV6UK]

Thanks for the replies – I now have a much better picture on how to progress. Just spent the afternoon after work looking at the two middle skins – and this has brought up a new question

The drawing show a 2 ½ overhang for the centre belly skin that is secured to the first wing rib – between the main spar and the rear spar.

Having laid out the two skins on my fuselage – and making sure I have the right overlap on the rib used to secure the two skins together – I am short of 2 ½ each side – more like 2 3/8 on one side and 2 1/8 on the other (measured at the rear spar mounting lugs)

The offset centre rib is slightly off to one side and I have to push the two skins a bit closer together to ensure I get the 5/16 edge distance for both skins at the joint on the rib.

Measuring on the wing at the rear spar –it looks to be just right .. but close – assuming the rear spar is pushed fully home in the mounting lugs.

How tight is that 2 ½ measurement ? I have some spare 2024-T3 so I could cut two new skins, if I really had to – Or would it be acceptable to rivet on a splice strip if the edge distance for the screws securing the centre skin to the wing is marginal ?

Jan

Very slow build ...

 

[Stevea]

How tight is that 2 ? measurement ?

The skin overhang will be trimmed later, when fitting the wings. Mine measures 2" at the forward edge and 2 1/4 at the back edge.

 

[WenEng]

Mine measures different on each side..

Pilot side 2 1/16 at front , 2 3/8 in front of the rear spar mount location.
Co pilot side 2 1/4 at front , 2 1/4 in front of rear spar mount. No trimming or nut plate drilling done yet. Waiting to set wing incidence first, then drill for the nut plates before taking the wing off again.

 

[JanRV6UK]

Thanks for the feedback ! When I got home from work today I got down on all four and double checked the two skins position on the rib to see if I could tweak the two skins slightly more apart.

Then measuring the overhang at each point I got

Pilot side : 2 1/16 front 2 3/8 rear

Co Pilot : 2 1/8 front 2 ¼ rear

It is relatively easy to estimate how much the skin will overlap at the front as one can measure from the outer spar bolt hole to edge of skin – This looks fine – Not a lot spare but plenty to go with.

At the rear it is not so easy – as it can “move around a bit” to set up the correct incidence – But assuming minimum edge distance for the rear spar bolt – the skin overlap looks to be right on the limit i.e. nothing would be trimmed off.

It looks like we all have “similar” skin length to start with – and clearly we do not have 2 ½ to start with – I wonder if this is typical ?

It looks like once the skin is secured to the wing – not much to trim away.

I just want to make sure I do not run short !