RV-7 forward fuselage floor stiffeners

Any suggestions/experience relative to reworking the joggles on the floor stiffners to improve the fit up?

I have been very impressed and complimentary toward Vans in regard to the quality of their kits. The quality and engineering is outstanding for the most part. Having said that, these stiffeners, and some others like it, leave a lot to be desired. This is the poorest-made part I've run into so far. They suck. The ends are lapped up on top of another angle and they've tried to joggle the end in an unnatural way so it can rest on the crossmember and still lie flush against the skin below. How are you supposed to rivet this to a flat skin without distorting it?



The problem is obvious:



So what did I do? I clamped the stiffener to my backriveting plate on my workbench. The end is lapped up on top of a scrap piece of angle that's the same thickness as the bulkhead in the fuselage that this part will be riveted to. I used this big hammer and my biggest, baddest bucking bar to beat the **** out of this part to try and flatten out the bottom while maintaining and improving the joggle on the end.



I improved it enough to flatten it out so it won't distort the skin, but I still wasn't happy. You can also see that I tried putting in a flute so the material on the vertical side of the angle has somewhere to go as you try to bend it upwards into a decent joggle. I wasn't totally happy with this either. I don't like the look of the flute and I wouldn't do it again. I'm not sure it helped.



In the end, I wasn't happy with the appearance I ended up with, but I did at least get it to lie flat and not distort the skin. Then, rivet it together and build on. It's about the best that can be done, unless you have some very elaborate and expensive metal-forming equipment of some kind.

It's been a while, but I'm pretty sure mine looked a lot better than that. Call Van's.

(There are other areas where I've had major complaints, but not there.)

Charlie

Me too

I'll have to second what Bruce said above. Mine looked exactly the same as his did. There are other locations besides the floor stiffeners which also require a joggle in the aluminum angle, such as the aft end of the F-719 forward longerons. On my slow build fuselage, I had to take a hammer to these as well and it wasn't particularly pretty.

Back when I did this, I wondered if I had perhaps been unlucky to get a bad part. Since I live close to Vans, I drove down there and showed them this part. They were nice enough to walk me out into the warehouse where the box of these stiffeners was on the shelf, and allowed me to pick through them to see if I could find a better one. They were all the same. And all just like the one in the photos above. I hope by now perhaps things have improved, but since this question came up on this thread, my hunch is it's still the same.

On my -6A, Van's directions had me cut off an inch or so of the vertical part of the angle, and then form the jogel. The bottom of the angle stayed flat against the floor, and the jogled part stayed flat on the lower firewall angles.

Thanks for the input. I think I may go with a combo of flute and material removal, i.e. try to maintain as much stiffness as I can.

Rick Krueger

Have you tried taping a steel spacer to either side of it as a forming die and then clamping it in your bench vice (with soft jaws of course) to form it?

Check the EAA video on making Joggles

hayabusa said:

Have you tried taping a steel spacer to either side of it as a forming die and then clamping it in your bench vice (with soft jaws of course) to form it?

Click to expand...

There is an EAA Homebuilders Hints video using this kind of technique except it concerns sheet material rather than angles. Still, the technique might be of benefit, especially since the joggle is already formed (but mis-shaped). It can't hurt to try it before resorting to your hammer or hacksaw.

My own were quite good as delivered and certainly nothing like those in the pictures, so Vans are definitely capable of doing these right. I don't understand how their entire stock, as described by Bruce, could fall so far short of their own best standard.

I'll be getting to this step shortly after Oshkosh. I'm going to go work on my brakes and rudder pedals today, if I can. I just went upstairs and checked my stiffeners; sure enough they look the same. Thanks for the tip Bruce.

Joggle Tool

Here's the proper solution - make your own joggle tool (helps if you have your own machine shop). I agree, Van's should do a much better job of these joggled angles.
http://www.vansairforce.com/community/showthread.php?t=57134&highlight=tool+joggle

joe_rainbolt said:

I'll have to second what Bruce said above. Mine looked exactly the same as his did. There are other locations besides the floor stiffeners which also require a joggle in the aluminum angle, such as the aft end of the F-719 forward longerons. On my slow build fuselage, I had to take a hammer to these as well and it wasn't particularly pretty.

Click to expand...

[Off topic]
Joe, I just went through your Rough and Ready Aerospace blog, and it looks like you're doing very nice work on your RV-7!
[/Off topic]

Another vote for angle clips

I originally made angle clips for the F-719 because the factory joggle was ugly as a half eaten meat pie. I was hoping like anything that the floor joggle was a bit prettier, but this was not to be. What a waste of fine aluminium. For the step up onto the firewall angle, this can be done the same way as my F-719 with a spacer, however for the F-704A flange, this will actually require a step-down, so I will just fay seal a shim under the angle clip (just to hold it square) then rivet it onto the flange. Here is a picture of my F-719 step/angle clip. It has AN-426 rivets countersunk on both faces, and the rivet that holds it to the skin fits in between the two other rivets holding the angle clip to the F-719. The angle clip is trimmed down slightly so that it is flush with the F-719. It takes time to make and adds an ounce of weight, but gives you a bomb proof structure with a perfect surface finish. I just have to make four more for these F-772B floor stiffener. I now understand why they sent so much extra angle stock in the kit.
Tom.

I was thinking of something along these lines too, but was wondering about how strong the rivets are compared to the original joggled angle as well as how strong they need to be. I'd probably add more rivets to make me feel better.

Joggle

grayforge said:

I was thinking of something along these lines too, but was wondering about how strong the rivets are compared to the original joggled angle as well as how strong they need to be. I'd probably add more rivets to make me feel better.

Click to expand...

Same here. I was going to add shims to make them fit better but once the rivets are set, they seem fine. I always remind myself how many RVs are built to plans and consider the extra hours to engineer a mod.

grayforge said:

I was thinking of something along these lines too, but was wondering about how strong the rivets are compared to the original joggled angle as well as how strong they need to be. I'd probably add more rivets to make me feel better.

Click to expand...

The picture is similar to the plans version of the RV-6x firewall interface.

Specifies a 2 inch angle piece and a 0.063 as shown in the previous pic.

However, the only rivet attachment seems to be the use of longer 3/32 rivets through the floor board.

Cutting off the crumpled ends of the Van's longerons, then adding an angle piece, doesn't address alignment issues in instances where both legs must nest against mounting surfaces. My solution was new .062x.75x.75 angle (order three extra lengths with your fuse kit, tell Van's to keep their junk). Cut to length, make two saw cuts in one leg (one must be a "v"), joggle, then rivet over the cuts in assembly a strap sawed out of .062 sheet with a very shallow "z" that follows the sawed leg.

Both sides of the longeron will nest against adjacent surfaces, through rivets securing longeron, strap, and mating part.

John Siebold

Stiffeners

Replaced mine because the forward ends got bent slightly in the nose over. The new replacement parts from Vans fit pretty good. No tweaking needed. These parts purchased about 1.5 years ago. Maybe it's a batch issue?

Don Broussard

RV 9 Rebuild in Progress

Inboard and outboard floor stiffeners need to be different

grayforge said:

I was thinking of something along these lines too, but was wondering about how strong the rivets are compared to the original joggled angle as well as how strong they need to be. I'd probably add more rivets to make me feel better.

Click to expand...

I too first worried about this strength, but when I realized that they were only connected to the corresponding F-704 flange with one 3/32" rivet, I quickly came to the conclusion that the five rivets holding this angle clip to the main angle was more than sufficient. Also, not having the aluminium plastically deformed can only improve its fatigue life.

Yesterday I finished cutting and fitting the ones for the two inboard F-772B positions. John is right that these two inner positions need to nest up against the F-601J angle on the firewall and F-783B cover support rib, and thus need to be different to the outboard ones (which can be fabbed like the F-719). For this situation I just cut the horizontal flange off the angle and continued the vertical flange from the vertical flange of the firewall angle all the way to the F-704A, which allowed this vertical flange to be riveted to the F-601J and F-783B accordingly. You then have to make an 0.063" step for the forward end, then two straps for the horizontal connections to the firewall angle and the F-704A flange. These straps are riveted with three rivets (two holding the assembly together, and a third through the middle once it is riveted to the F-772 forward bottom skin). It is possible to meet edge distance requirements (2D) at all hole locations, assuming you drilled your holes correctly in the F-601J. I'll post some pictures once I have it primed and riveted together. A huge amount of work, but the fit is perfect. It sure makes me wish that better joggles arrived in the kit, or that someone with superior machining skills to mine could fabricate and sell a die to set these correctly. I would pay many $$$ to not have to go through this again.
Tom.

One of the inboard floor stiffener joggle replacements, yet to be primed and assembled.

Tom.