What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

F-996B,C woes

Paul B

Active Member
One thing I have discovered after several years of building is often the part you believe will be easy is not so easy! After a quick look at the instructions and plans, I anticipated an hour or so would be needed to fabricate and fit the F-996Bs and Cs. I am now at least 16 hours into this and really not close to completing them.

If I build them according to DWG 38, they can't go together the way I intuitively believe they should fit. From the outboard: F-970 skin, F-996B spacer snugged between the lower and aux longerons, F-9101 gear attach web tight to the longerons. The F-996C reinforcement angle would fit perfectly over the spacer with the F-9101 between them.

I emailed Vans and the response I got only confused me more. The plans show 6 holes 7/16" from the fwd edge on the outboard face of F-996C. The instructions say to draw a centerline on the outboard face and use this to locate the lowest of the 6 holes, making this hole center 3/8" from the fwd edge and not in line with the other holes. Vans told me the holes should be 5/16" from the fwd edge. Only one of these three can be right.

If I make the spacer to the dimensions shown on the plans it cannot be moved forward enough to sit under the reinforcement angle. I made a spacer 1/8" shorter. It fits, but this can't be right?? Further, centering the holes for spacer and reinforcement angle according to DWG 38 guarantees the two pieces will not perfectly line up.

I must be seeing this wrong since many others have done this easily. Any help appreciated.
 
Paul,

I just finished this section myself over the weekend. The F-996C angle's outer holes are incorrect on the plans, according to many other builders. I referenced Smitty's great site:

http://www.smittysrv.com/more_stuff.asp?ID=583&Section=574

The F-996B spacer's dimensions are correct. Personally, I made the spacer, and drilled the one hole. I then cut the angle, clamped to the F-9101, longerons, and side skin, and drilled from the side skin / longeron / web through the spacer to set those pesky outer holes (who cares what the blueprints say, drill with the holes that actually will hold bolts!). I took the angle off, marked the locations of the inner bolt holes on the angle, reclamped / clecoed and drilled through the angle, into the web and side skin. Took off the angle and F-9101 web from the longeron and side skin, reclecoed the angle to the web, and then drilled the inner 3/32" rivet holes through both. I then took the F-996B spacer, ground it down to fit in its area on the side skin between the longerons, clamped (okay, taped) to hold, and drilled the bolt holes in the spacer, through the skin's holes, into the spacer. *Finally* I clecoed the spacer to the F-9101 using the new bolt holes drilled, and drilled the 3/32" keeper rivet holes through the web into the spacers.

Clear as mud, right?
 
Last edited:
This is my journal entry from long ago.

2005-08-30 Hours: 6.17 Category: Fuselage Manual Ref: 8-8 ID#: 732
Me and my F-996C's
In football terms, I ran four plays up the middle, gained about a yard and turned the ball over on downs. Started the day screwing up one of my nicely made 996C angles. Drilled the top hole to #30 and test fitted to the fuse. The hole didn't line up so I had to make another one. Glad I only drill just the one. Well, after the third attempt making another one, I got it right. Hint: do not pre-drill any holes in any of the 996 parts. They are more of a custom fit. Vans' plans assume mathematic perfect. Not happening here. Clamped the 996C-L into place and then drilled the top hole. Drilled the lower longerons to the skins. I had not done this earlier because the manual says to "clamp the aft end for now." But you have to do that in order to line up and drill the bottom hole on the 996C's. Also had to trim some off the top edges of the 9101 gear webs to get them to fit and allow the holes in the 713 aux. longerons to line up the the 970 skins holes. I drilled all the initial holes in the 996C's and installed the left one. Had to trim some off the top edge of the 996B to get the pre-drilled hole to line up with the 996C. I would recommend not drilling the hole in the 996B, just line it up and drill in place. You need to make sure it will fit before riveting it to the 9101/996C. Once done, I temporary-riveted the 996B, 9101, and 996C with the keep rivets and clecoed the assembly back onto the fuse. Still have the right side to do."
Photos:
The left 996C-L "take four" drilled and clecoed into place.
 
Hum, O the memories of that one, I actualy have a video on my build site (drilling a big hole in fuse) but i do remember making two or three of those :D
 
More of a guideline

I've come to appreciate that when it comes to fabricating parts the dimensions on the plans are more of a guideline than gospel. Whenever possible take measurements off of the part(s) that the fabricated part will connect to and make adjustments from there.
 
moving on . . . finally!

Two weeks and more hours than I care to admit, I am done with this task! Thanks everyone who posted, all responses were helpful. A few thoughts for those who haven't completed their F-996Bs and Cs:

1. Make these pieces to the dimensions shown on DWG 38, but don't drill until you have reviewed some techniques that others have used for locating the holes.

2. You will likely have to remove some material from these pieces to get them to fit.

3. If the pieces are made according to DWG 38, the spacer will not be directly under the reinforcement angle but will be slightly aft of it (with the F-9101 between them). This was a source of great confusion for me but I have since come to understand this was probably how Van intended it to be.

On to the rudder pedals. This looks easy . . .
 
F-996C Help

Great advice and pictures in this thread, but I am still having a real problem with these very simple parts. If I follow the drawing, the upper hole in the F-996C angle does not line up with the existing hole in the side skin. This looks like a common problem.

If I follow the advice found here and match drill the hole in the F-996C angle using the side skin as a guide, I will end up with very inadequate edge distance for the upper 3/16" hole.

I'll send an email to Vans to get their advice. Meanwhile, has anyone fully cracked the code on these parts.:confused:
 
One thing I have discovered after several years of building is often the part you believe will be easy is not so easy! After a quick look at the instructions and plans, I anticipated an hour or so would be needed to fabricate and fit the F-996Bs and Cs. I am now at least 16 hours into this and really not close to completing them.

If I build them according to DWG 38, they can't go together the way I intuitively believe they should fit. From the outboard: F-970 skin, F-996B spacer snugged between the lower and aux longerons, F-9101 gear attach web tight to the longerons. The F-996C reinforcement angle would fit perfectly over the spacer with the F-9101 between them.

I emailed Vans and the response I got only confused me more. The plans show 6 holes 7/16" from the fwd edge on the outboard face of F-996C. The instructions say to draw a centerline on the outboard face and use this to locate the lowest of the 6 holes, making this hole center 3/8" from the fwd edge and not in line with the other holes. Vans told me the holes should be 5/16" from the fwd edge. Only one of these three can be right.

If I make the spacer to the dimensions shown on the plans it cannot be moved forward enough to sit under the reinforcement angle. I made a spacer 1/8" shorter. It fits, but this can't be right?? Further, centering the holes for spacer and reinforcement angle according to DWG 38 guarantees the two pieces will not perfectly line up.

I must be seeing this wrong since many others have done this easily. Any help appreciated.

Eight years later and Van’s has not revised the drawings to fix their dimensions. They are perfectly content to let every builder step in the same hole. (I just stepped in this hole)
 
Back
Top