SmittysRV

SmittysRV

Well Known Member
I made the 2 F-996C reinforcement angles and drilled one hole on one end like the plans said, but when I tried to cleco the angle to the fuselage, the hole did not match the hole in the skin. So I had to make 2 more angles. This time I use the holes in the side skin to determine where the top and bottom holes go in the F-996C reinforcement angles. This picture shows how the actual holes in the angle are different from the holes the drawing. Note: My camera has a goofy wide angle lens which makes the angle piece look bigger than the drawing, but it's not.

angle1.jpg


Here's the measurement between the holes in the skin:

angle3.jpg


Here's the measurement between the holes on the drawing, using both the drawing lines and measurements on the drawing:

angle2.jpg


An finally, here's my question. If the holes on each end of the of the angle are not mark correctly, how can I be sure that measurements for the inner 3/16" holes are correct? These holes will have the bolts in them that hold the tank bracket in place.

Thanks for your help!
 
Inner holes and tank attachment brackets

I just completed fitting the tank attach brackets using the two center holes to which you refer. I fabricated the brackets very early on (I initially went through the plans and fabricated all required parts before starting construction.) In this case, and some others like the F-912C (elevator stop angle), I advise fitting an unfinished, slightly oversized part (in terms of the length and depth of the flange the sits flush to the fuselage in the case of the tank attach bracket). Then drill the fuselage attach holes and then cut down to size to assure that you will have appropriate edge distance on the holes. I ended up slightly under on one angle with the holes too close to the long edge of the flange. On the other, the top hole was perfect but the bottom hole was slightly too close to the end. If I had waited to cut down to size after drilling, I could have compensated.
 
Smitty,

I had the same issue when following the directions, ie., predrill the top hole. I then cut two more a little oversized, marked a center line, then carefully trimmed until it fit snug between the aux and bottom longerons and the line showed through the holes in the skin. Then drilled using the skin as a guide.
 
Thanks Guys!

I guess the drill (excuse the pun) on this one is make the parts without drilling anything and custom fit the parts and drill as necessary.
 
Don't measure lines on the plans

Don't expect accurate numbers when physically measuring distances on the paper plans. There may be scaling issues with the plotter, and the paper will grow and shrink with changing humidity. A standard practice, when accurate measurements are needed from plotted drawings, is to include a 10" x 10" grid on the plot, plot them on Mylar, a more stable material, have QA certify that the grid is within specifications. Without that, the actual line drawings will be off an unknown amount.

Vans makes several references to this in the instructions including a warning that the paper template for the longeron might be the wrong contour and to use the canopy deck part as a more accurate reference when bending, and when bending the slider track 45 degrees, to check it with a protractor and not the drawing profile because that may be off.
 
I didn't use the templates as a go-by. I strictly used the written measurements. The measurements for the end holes are incorrect.
 
Last edited:
You must log in or register to reply here.