When to final drill side skins to Longerons aft of top skins

Hello, I am on section 10-12 where I attach the top skins and then final drill all common holes with a #40 drill including the top and side skins to the longerons. It states to match drill the two top skins but it does not mention when to final drill the longerons to the side skins aft of the top skins. They are currently drilled with a 3/32. The are the side skin holes under the Horizontal Stabilizer

Do I do this now or does this happen later on.




Thanks

Back on page 10-11, step 2, you were supposed to drill the lower side skins to the longerons. When doing the top skins, I just removed the clecos for the section I was adding (ex. left side for top aft skin) and then replaced them in the pre-punched holes in the skin I was adding. For the aft skin, I started in the center and match-drilled to the fore and aft edges. For the forward skin, I started at the aft edge and worked forward. I did not have any problems such as enlarging the previously drilled holes in the lower skins or longeron.

#40 match drill Longerons aft of top skins

Hello Patrick

Thank you for your response.

Page 10-11 step 2 does call for match drilling all those holes but only with a 3/32 drill. This is an undersized drill for a -3 rivet. I imagine that they wanted us to use the 3/32 so that when we placed the top skins on and they overlapped the side skins, we would then match drill with a #40. This is what I did and it came out well. But it never tells us to match drill with a #40 the side skins/Longerons aft of the top skins. The directions are specific to only final drill the top skins to side skins with a #40.

I have read ahead and I see where we do indeed place a -3 rivet in those holes under the HS (ecept the fairing attached holes) and it a a shorter rivet than those with the overlapped top skins which make a lot of sense. I think I can match drill them now using a #40

I did this step last night, specifically only match drilled the aft ones, tomorrow at some point I will match drill the forward ones. Something to note is 3/32 is the same as a #40... Which fits AD3 rivets. So if you drilled these all with a #40(3/32) bit then you are fine.

Uh, no...

A 3/32" drill is .0938" and a #40 drill is .098"...

There are specific differences between fractional, number, and letter drill sizes.

Sorry, step 2 does say 3/32. But then the next step says to match drill all the side skins to bukhead and frame with #40. Since the longerons were in place, I took that to mean they were 'frame' as well. In any case, the side skins were #40 into the longerons before the top skins were added and it came out very well.

rocketman1988 said:

A 3/32" drill is .0938" and a #40 drill is .098"...

There are specific differences between fractional, number, and letter drill sizes.

Click to expand...

Why do they seemed to be used interchangeably in the plans? As noted above it will specify 3/32 or 1/8 then come back and call them #40 or #30 respectively.

3/32 vs #40 and my theory on why

I too have noticed the plans sometimes appear to interchange 3/32 with #40 but if you read the directions diligently and in order, it makes sense (to me anyway)why they call them out differently.

Specifically when attaching the side skins of the RV-10 to the Longerons, the side skins need to be clekoed to the longerons so you need to drill them enough for a silver cleko to work. But later, the top skins overlap these same holes and need to be match drilled through the side skins and into the longerons. If we use a 3/32 again or if we originally used a #40, we might end up with some oval holes as the skins might shift slightly during the drilling of the overlapping parts.

If we use successively larger drills 3/32 then #40, we may end up with rounder holes that may be riveted together with more structural integrity. (?)

Just my two cents. YMMV

I will be calling Vans tomorrow and double checking on when to #40 match drill the longeron to side skin holes under the aft deck. I was able to do enough work on the plane today without having to make that decision today.

Regarding the definition of Frames vs bulkheads vs skins vs longerons. My reading of the plans on the RV-10 section 11 determined that the plans are quite specific. The frame and skins do not include longerons. The frames are the F-1007, F-1008, F-1009 etc. The bulkhead is the F-1006. The stiffeners are the J-Channels and the Longerons are the "longerons" or the F-1032.

I am probably overthinking this (I am an engineer so I am prone to doing this). As I wrote above, I will call Vans in the AM and confirm I can match drill the side skin to longeron holes under the AFT deck now with a #40 drill. (basically enlarge from 3/32 to #40).

Good dialogue Thank you everyone.

Let us know what they say. I ordered an "RV-10 toolkit" with a good amount of drill bits but no 3/32. I have a 3/32 countersink bit, 3/32 dimple die and 3/32 drive punch... have been using the #40 when it calls for either or... I hope I don't fall out of the sky!

Happy Monday everyone,

I just talked to Vans. We quickly went through the plans on 10-11 step 2 and 3 and then page 10-12 step 9. His feedback was if I already drilled the side skins to Longerons under the aft deck with a 3/32, go ahead and match drill to #40. Any fairing screws, which some of these will be used for, will be enlarged for the fairings anyway.

We did look at the instructions and he indicated the #40 drilling was probably best called out in 10-11 step 3 even though that step does not call out drilling of the longerons.

I then asked when the plans call for using a 3/32 drill, can we substitute a #40 drill. The response was if the plans call for a 3/32 drill, use a 3/32 drill.
Based on the above responses, my suggestion to others is on section 10-11 step 2, drill using a 3/32 drill. On step 3, drill only the holes associated with the sides skins, and frames (not longerons) using a #40. this is exactly as called for in the plans. Where I would augment the plans is on section 10-13 between step 3 and 4 to match drill the side skins to the longerons under the Aft deck, after any additional adjustments are needed based on the instructions. That is the step on I am on now and it will work out just fine. I guess you could also final drill to #40 after Section 10-12 step 9 as well.


I will final drill the holes today to #40 and then start my disassembly of the cone.

Thanks- trying not to hijack your thread but this might help someone out. Just shot Vans an email myself, since my interpretation of 3/32 vs #40 has been off since day 1. I'm a bit concerned where I used a #40 instead of a 3/32 or #30 instead of a 1/8. Concern would be something maybe misaligned and I didn't notice by going straight to the #40 or #30.

Searched though the planes and found only 2 instances - one which I'm on so I Can correct it mid step of using a #40 bit when it called for a 3/32; 8-5 step 2, 10-11 step 2. Also found 2 instances of where I used the #30 instead of 1/8; 6-2 step 2, 8-8 step 1.

Hopefully Vans doesn't tell me to scrap the parts, moving forward I'll get some 3/32 and 1/8... because at some point on the fuse or wings I might have to use those.

I see a trend on 3/32 then #40

Hello,

Section 8-5 does say to use a 3/32 for the spar caps to the spar flanges. Then later, once the skin goes on, you drill through those holes again, only now with the skin on (3 layers) with a #40. So it does make sense to use a 3/32 when match drilling holes but when at least one more layer will be added later.

Good to know. Enjoy the build!

That makes complete sense... Just ensures a tight as fit as possible I suppose. Thanks for the post, wouldn't of figured out my ignorance on my own

Response from Vans on my issue "You should not have a problem with what you have done to this point. As you said from this point forward you should use what is specifically called for in the plans pages."

So last night I used the 3/32 to match drill the forward parts of the longerons... much tighter fit and fact my hands hurt from attaching the top skin on after I drilled.