[briand]

I am at this stage now and I bent both of these the same after mesureing, checking level and plumb then scratching my head trying to figure out what the deal is I finally determined that the WD on the left angles down (as jigged) about 2 degrees more than the right. Should I just bend the factory bend a little more?


OR....(and I know Vans rule about forcing any of the longerons into position) should I just force it? It doesn't take much and since its the firewall weldment thats out, forcing it aligns the weldment to just about match the right side.

 

[grover]

caution

I urge caution and lots of double checking in this area. mine is off by a little. . . I don't remember if I modified the factory bend to make things fit better, but the end result of the dimensional variance was the side skin didn't line up as well as it could have and edge distance is marginal where that longeron attaches to the landing gear weldment.

 

[briand]

I'm building a TD so the landing gear weldment shouldn't be an issue. My question would probably be better asked to Vans but I though I'd see if this has happened before. I'd bet these firewall weldments are often off a little.

 

[ptrotter]

I think you may find that the firewall weldments are not perfect so you may have to adjust the bend slightly. However be very careful as this is one of the few places where a 1/16" makes a difference or you will have trouble with the gear box weldments. You need to check a bunch of measurements in this area. First make sure that the vertical measurement of the bottom (top as jigged) of the 804 bulkheads are the correct distance above the reference line (top of jig). This makes a big difference when fitting the gear box weldment that fits right below the longeron you are working on. Mine was a little off here and it caused me no end of grief gettting things to fit right. I would put the side skins in place and see how they fits against the longeron as well. Make sure that the 2 tabs line up EXACTLY with the longeron. This sets the proper distance between the main longeron and this longeron. Read ahead in the instructions so that you see how it all fits together before doing anything.

Good luck,

 

[Steve Ashby]

Your lower longerons are not fit right

Briand,
I am building an 8A and am about 1 week ahead of you in construction. Your photo shows the lower longerons fitting inside of the flange of the 804 bulkhead. I think they are supposed to fit flush with the outer edge of the flange, if I am reading the plans right. It has taken me two days to massage the forward side skins to the point where they fit the parameters outlined in the plans. Just like the fuel tanks, nothing will line up or fit at first, just keep working at it until it all goes together.
Good luck

 

[briand]

Briand,
Your photo shows the lower longerons fitting inside of the flange of the 804 bulkhead. I think they are supposed to fit flush with the outer edge of the flange, if I am reading the plans right. It has taken me two days to massage the forward side skins to the point where they fit the parameters outlined in the plans.

From what I can tell the 843 is supposed to stick outbord of the 804 flange by about .063 (its more like .080) to meet up with the side plates you make out of the .063 that came with the wings. The OIS also says you may need to file that aft vertex of the 843 round so those side skins will fit/lay better.

It is inside a little but that was because it was a little low when they are forced up into posittion they line up with the 804 flange a lot better.

 

[mlwynn]

Longeron to motor mount

Hi guys

I am at that same spot. I did the same careful bend and flatten. When I got it in, it required a little more hammer encouragement to fit exactly without any force. I did find a gap at the front end between the longeron and the motor mount. It looks the the motor mount is not bent exactly correctly. I scratched my head for a long time on this and finally made a shim to close the gap. The left side required 0.40 and the right a taper from 0.063 down to 0.40. Shimming makes more sense to me than pulling it over with a clamp and leaving all the tension in the airframe. Anyone else have this issue? My first attempt at posting photos follows.

Regards,

Michael Wynn
RV 8 Fuselage