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Burrs on the wing spars

Debovsky

Active Member
While unpacking the crates, I was having a close look at the wing spars for an initial inspection. To my surprise, I noticed that there are burrs on pretty much every edges of both spars cut-outs and contours. You definitely feel them when slipping your finger on the edges.

IMG_2515-BURR_zps81289545.jpg


Is it me or I'm too picky? I guess it is out of the question to think about trying to smooth these out. In that case, why should we file and "polish" the other parts like crazy while the spars (and we're talking about a major structure element here) are having edges which have been barely smoothed out?

I'd like to hear your thoughts on this.

Thanks.
 
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I was concerned about these too but Vans said that its not a big deal.

I can't tell on yours but with mine, they were more like tooling marks than burs. There wasn't anything that I would worry about cutting myself on when I run my finger over it and there wasn't anything loose that interfered with parts fitting together.
 
I can't tell on yours but with mine, they were more like tooling marks than burs.

Correct, they are tooling marks left by the punch press that makes the parts.

Pretty much every part that is made from sheet stock will have these along the edges. At least the straight edges------not sure about curved edges.

Interesting process to watch, if you ever go to the factory ask for a tour.

rv10%2520019.jpg
 
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In our airplane factory, we would never let tooling marks like that out the door. It is definitely an undesirable situation. However, there is likely plenty of margin left even with the flaws – and that’s likely why Van is unconcerned.

It would be better to have the edges polished, yes, but the cost of doing so would be getting into diminishing returns. Remember, you are buying a "value priced" airplane kit - not a deep space probe. In other words, Van has cut some corners, so you get what you pay for.
 
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Yea ... I noticed a similar thing with my new, shiny, yellow anodized spars for my -7. The prefab web punchings seemed to have relatively sharp edges ... far more than I'd tolerate if I was deburring a a regular kit piece that I would then prime and assemble. Not horrible, but a bit sharper than I would expect.
 
Design Compromise

I prefer to use the term "design compromise" vice cutting corners. All engineers must make design compromises in nearly every project in order to meet the design goals of the customer. In fact you see the same in aviation safety - In the Navy we absolutely have found a way to prevent any aviation incident, but it's application in unacceptable...stop flying!

I too posted and called Van's about the spars and was told the same..."we used to, it will not affect anything, build on"
 
As the manufacturer of the airplane, I consider deburring parts, as necessary, my job. If you are concerned about exposing un-anodized metal, shoot a little primer in those areas.
 
I prefer to use the term "design compromise" vice cutting corners...

I'm familiar with "design to cost" and other design scenarios as my primary employment function is establishing design requirements and selling our aircraft product to the Government.


For an example of a design "compromise", look at the typical control surface hinge Van is so fond of. Using rod ends as pivots gives you the penalty of a very unfavorable strength/weight ratio in exchange for the benefits of adjustability, low cost and easy availability. That's a "compromise" in design.


In the case of the wing spars, van has made a choice to ignore a finishing step in the manufacturing process. This is a conscious and deliberate decision based on cost - i.e. an example of cutting a corner.

This is not a slam on Van- He makes a fine product at a good price. But let's not sugar coat the subject, these aircraft are not the pinnacle of aeronautical engineering design. They are simply "good enough".
 
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