Dimpling Front and Rear Spars

[scottT]

I just finished dimpling the skin flanges on the Front and Rear Spars (HS-702 and HS-603). I was somewhat surprised at the amount of bowing this operation created. Dimpling the flanges stretched the skin attach flanges to the point that the HS-603 bows 3/3" at mid span.

I am assuming that this is not uncommon?

I also assume that I should not try to straighten these? Have seen no instructions to flute for example.

Thank you in advance for input.

[Spike]

If you need to flute to fix things then do it. There are a bunch of things that vans will never tell you to do.  Take a flexible straight edge and use it to make sure that the holes are in a straight line.

Sent via DROID on Verizon Wireless


-----Original message-----

From: RB Lists - RV7 <support@rivetbangers.com>
To: rv7@rivetbangers.com
Sent: Sun, Aug 29, 2010 16:13:05 GMT+00:00
Subject: Dimpling Front and Rear Spars



I just finished dimpling the skin flanges on the Front and Rear Spars (HS-702 and HS-603). I was somewhat surprised at the amount of bowing this operation created. Dimpling the flanges stretched the skin attach flanges to the point that the HS-603 bows 3/3" at mid span. I am assuming that this is not uncommon? I also assume that I should not try to straighten these? Have seen no instructions to flute for example. Thank you in advance for input. rivetbangers.com - Discussion topic http://www.rivetbangers.com/forums/viewtopic.php?p=34838#34838

Submitted via email

[scottT]

Spike,

If I use finger pressure I can push the spars down flat.

Thinking that I might just use them as is. I am worried that if I flute these after match drilling everything that the spacing may change and the skin holes will no longer line up.

Might try just clecoing everything together to see how that goes.

Thanks,

Scott

[dons]

Scott, one other thing to check is that your dimples were done enough. I seem to recall having something like you describe before I figured out it was because I hadn't used enough pressure doing the dimples.

You might want to test that theory by bending a piece of scrap at 90 degrees, putting some holes/dimples in one flange and see if you can cause the same thing using the same pressure, then dimple them with more pressure and see if the bend goes away.

Just a thought, value it at what it cost.

[scottT]

Don,

I think I may have had more than required pressure thus stretching the flange.

I just got of the phone with Van's they said that this was not uncommon. They said that I could flute if I wanted to but that it was probably more effort than it was worth. They suggested that if I cleckoed the stabilizer together and everything pulled in that I would be good to go without fluting.

I assembled the HS and everything seems OK.

I have decided to build on.

Thank all for responding,

Scott