SteelMike

SteelMike

Well Known Member
I've been building my -7 emp all out of order, and I've finished the vertical stab, right elevator, and partial complete on the rudder, and now I'm going back to the HS. Here's the question: why are the inboard-most ribs on the HS (HS-404 and HS-405) undrilled? I got a lot done today and then was looking at the final assembly/drilling of the HS and I just said to myself, "quit while you're ahead", and I walked away. I'm kinda worried I'm going to build some twist into the HS in that we have to drill all the holes on those most important ribs.

Does anyone know why those ribs come undrilled? Like, maybe if I know why they're not drilled I might know what to avoid? I'm trying to figure out what the story is before I put a bunch of holes in metal...
 
hmmm... Im assuming the 404 & 405 issue has the skin pre-punched and not the ribs... If thats the case, you just put the rib in, clamp it in place as best as you can, get everything lined up, and match drill the rib to the holes in the skin... I'm not 100% sure why they do that, probably has to do with the bend in the HS... perhaps it wont line up correctly until after the bend so they make you drill the holes yourself... dunno. I dont think twist is of concern as long as you have everything centered and lined up...

hs.jpg
 
400 series part

I thnk the 400-series parts are designed for the RV-4, and are still sold to -4 builders, in which case a pre-punched version just wouldn't work. Van (and you) can reduce manufacturing costs by using identical parts for multiple aircraft. In any case, it is a simple piece to insert and drill.
 
Parts from the 4

Since the part numbers start with a '4', I thought they would be from the RV4 parts inventory. Since the 4 is not match-drilled --- voila.

Vans re-uses parts from older plans where the can to save part count.

That's how I rationalize it
 
Who can truly know the mind of Van? But you will find numerous places throughout the kit where some of the holes are left undrilled. Most seem to be in areas where, like this, you are making manual bends to some of the structure & it's very unlikely that your bend would be exactly like my bend etc etc. For instance, there are no holes at all in the main longerons.

An additional factor might have been preserving 51% status under the whim of the FAA policy current at that time.

Charlie
-7 finish kit
 
I figured the -4 parts getting re-used and the differences in your bend and my bend, but I'm still a little nervous. Oh well, onward, upward. I'll just charge ahead and hope I don't make any expensive errors.

Speaking of expensive errors, I keep hearing about how cheap Van's parts are, but I just got charge $150 for two pieces of aluminum (HS-600pp I think - they're the two long tapered reinforcing strips on the rear HS spar), and about $70 for the two HS-702 rear spar pieces. Total bill was $256. Doesn't this seem pretty stiff?

btw, if you're curious, I drilled the attached holes to #12, not #21. Doh! This also explains why my build has been so drastically out of order.

Dyslexia: 1 - Mike: 0
 
You're not the first...

SteelMike said:
btw, if you're curious, I drilled the attached holes to #12, not #21.
Click to expand...

Not sure which holes you are referring to so this trick might not have worked, but remember that an AN3 bolt uses a #12 hole and is stronger than a #8 screw or -4 rivet. Costs a tiny bit in weight, but saves a ton in $$$ on new parts.;)

Roger
-9A slow QB
 
I called vans to make that same plea, but they said no dice. Oh well. The parts are already here and we're moving forward. I just hope that it doesn't cost me $250 bucks every time I have a dsylexic moment. I keep hearing about these $4 parts, but that's not my experience!
 
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