Vertical Stabilizer

[at7000ft]

Just realized that I have a 24 degree spar stiffener also, problem is my vertical stab is riveted. No problem, just did as Dan suggested and put a 2x4 behind the stiffener and squeeze at the bend with a couple large clamps to get it to the correct 19 degrees.

RH

[RonFranck]

Thought I'd weigh in on the forward spar stiffener. I have an early kit and my stiffener also measured out at 24 degrees rather than the 19 degrees called on the plans sheet. I have not yet corrected the bend but rather I have moved forward with fixing the skins to the frame for initial drilling and up-drilling. During disassembly for deburring I'll address the incorrect bend and return it to 19 degrees.
<--------<<< That's gonna' be my own Panther one of these days that I'm sitting in.

[GlenNJ]

I'm ready to rivet my vertical stabilizer's forward spar channel to the spar stiffener. Dan, why are the rivets oriented opposite from the other tail section spar assembly's (on the other assembly's, the shop head of the rivets are on the spar channel side of the assembly)? I'm looking at plan sheet P-T-HT/VT- spar details, section D-D. Aren't the shop heads of the rivets supposed to be on the thinnest metal side of the assembly (in this case, the .032 spar channel)?

[GlenNJ]

This probably won’t appeal to most builders, as most will use the pulled rivets to assemble their tail kits spar channels to the spar stiffeners. For those that choose to use the optional AN470AD, and AN426AD rivets for these assembly’s, I can say the back riveting tools sold by Cleaveland Aircraft Tools work exceptionally well. I tried experimenting with a rivet squeezer to set solid rivets. I also tried setting these rivets with a mallet, and a C-frame. I couldn’t get consistent results using either method. I ordered the back riveting tools from Cleaveland Tools, and the quality of workmanship I can achieve with these tools is excellent. I used AN470AD-4-7 dome head rivets, and AN426AD-4-7 flush head rivets to assemble the .1875 spar stiffeners to the .032 spar channels. I modified my Avery C-frame (mine was the newer aluminum one, I’m not sure if the older steel ones can be modified) as per the Cleaveland kit, and used a US tool, TP-83, 3X rivet gun. I set the rivet gun on a high setting, and used 65 psi air pressure. I drove the rivets with 4 second bursts, and held the rivet gun firmly against the rivet. This gave consistent, quality driven rivets. An important step is to measure each rivet after setting, to make sure they fall within specs. The list of tools needed for the tail section are:

-C-Frame (Avery or Cleaveland)
-3X rivet gun
-100 degree dimple dies ( $13.00 and up)
-RSB12 Back Rivet set 12” (Cleaveland tools, $34.00)
-ZCF AVERY C-frame retrofit kit (Cleaveland tools, $36.00)
-RSM10 1” mushroom set (Cleaveland tools, $15.00)
-RSC43 1/8” cup rivet set 3.5 (Cleaveland tools, $8.80)
-RLG-1 Rivet Gauge (Cleaveland tools, $15.00)
-1/4 pound AN470AD-4-7 rivets (Aircraft Spruce, $5.63)
-1/4 pound AN426AD-4-7 rivets (Aircraft Spruce, $5.49)

[GlenNJ]

Eric,
Thanks for your advice. It helped me a lot. I tried to do what you said and clamped everything to my vise. This didn't work, because my vise isn't mounted to a sturdy enough base to handle the pressures needed to bend the stiffener. I then figured I could do the same thing by laying a piece of 3/4" plywood over the lower portion of the stiffener, and clamping it to my work table. I angled the other portion of the stiffener up, and clamped plywood on the bottom and a 2 x 4 on the top. This held it in place nicely, and gave me enough leverage to bend the angle back where it should be. It took quite a few attempts, but I finally got it right. It takes a lot of pressure to bend the angle in the stiffener. It's a little scary putting that much pressure on the assembly, hoping you bend it enough, but not to far.

Glen

[muehlberg]

Glen,

I had the same problem. This was my non-factory approved solution. I don't recommend beating on it. I used a vise and some simple leverage. I cut two pieces of 1 by wood to match the bottom end. Placed one piece on either side of the bottom of the stiffener and locked in the with the edge of the vise just below the bend line. Then is used a 2x4 on one side and a 1x4 in the other side of the top portion of the stiffener and clamped them together. I kept the wood an inch or so above the bend line. Then using the 2x4 for leverage, I gently worked the stiffener into the correct angle. I then assembled the vertical stab. Later everything line up perfectly when mounting the vertical stab to the horizontal stab. It was not hard to correct when working with just the stiffener. If the vertical stab was assembled, I believe it would be a bit more challenging. Sorry, I didn't take any photos, I was just trying the correct it. Your the only other builder who has brought this up. I just figured I was the only one who encountered it.

Eric Muehlberg
Panther SN 11

[GlenNJ]

I have been prepping the vertical stabilizer parts, and ran into some problems while checking the angles. The prints show that the vertical stabilizer's forward spar stiffener should have a angle of 19 degrees. Mine came at an angle of 24 degrees. If it doesn't hurt to take this angle back out, what is the recommended way to do this? I was thinking of laying a 2 x 6 over the long part of the stiffener, and clamping it too my work table (one edge resting about where the angle starts). Then I'd like to lay a 2 x 4 over the short end of the stiffener (this end will be in the air), and carefully beat the angle back to 19 degrees, with a sledge hammer. Is there a better way to do this?

Glen