Plans help needed

flydjd · #1 07-23-2008, 10:10 AM

Hi all,

It's dumb Q time.......re this 7 Dwg detail for the Tank bracket attachment for the bend location

I am having a practice " senior " moment.... what do the measurements approx 17/32 and approx 23/32 on this detail relate to ? Are they supposed to be ref the large area washer ? (the position of which could vary )

Norman CYYJ · #2 07-23-2008, 10:18 AM

Make the bracket if not supplied. The newer kits steel brackets are supplied which must be fitted. Place the bracket on the fuselage and then determine the bend angle and the hole position. If done from the plans you may find that it won't fit and needs a lot of adjusting. So it is easier to start with a straight bracket and work from there.

Mel · #3 07-23-2008, 11:01 AM

I believe these dimensions are from the start of the radius to the bend line on F-796A.

noelf · #4 07-23-2008, 01:04 PM

Good catch on the details...but not to worry.
I am assuming that the fus, wings, and tanks are assembled, and attached to the fuselage.
And that the fuel tank attach bracket is riveted to the tank.
And that you are fitting-up the attach bracket that will be bolted to the side of the fuselage.

The wing has a dihedral, in that the wing tips are higher than the wing root. This causes the tank attach bracket(s) to be rotated somewhat from a straight line. The referenced 17/32 and 23/32 numbers are showing an approximation of the distance between the (you bend it) bend line and the valleys that are formed as the two brackets meet. I'll bet that the folks at Van's measured this several times, with several different engineers, using several different scales. Hence, the "approximate" dimension.

The take away here is that the two brackets do not reside on the same surface plane. They meet at an angle (the fuselage is tapering "in" as it moves forward. Your task is to get the two surfaces parallel, with no gap. The referenced bend line is a guide as to where to start looking as you determine your own bend line placement.

kentb · #5 07-23-2008, 01:40 PM

Quote:

Originally Posted by noelf

The take away here is that the two brackets do not reside on the same surface plane. They meet at an angle (the fuselage is tapering "in" as it moves forward. Your task is to get the two surfaces parallel, with no gap. The referenced bend line is a guide as to where to start looking as you determine your own bend line placement.

Correct, the easiest way to do this is after the wings are attached and the incidence is set, then make the bracket. Adjust them with a soft mallet until the fit with both surfaces.

Kent

rv9av8tr · #6 07-23-2008, 02:00 PM

Kent is right.

This is a really thick bracket and not easily bent just where the drawing says. I put mine in a vise and gave it a couple good wacks with a rubber mallet until it fit flush on both flange faces.

Happy hitting!

flydjd · #7 07-25-2008, 04:59 AM

Quote:

Originally Posted by Mel

I believe these dimensions are from the start of the radius to the bend line on F-796A.

Thanks all but Mel esp. Having extended the lines on my full size plans it seems that this is the "best" answer.

I realised what was needed to bend the bracket...just wasn't sure about those approx dims.

As a side note Gus at Vans says that the flanges which butt up against the fuselage sides should be at 93? - on both of my supplied brackets the top flanges are at 94? and the bottom ones are different at 89? - so some whacking of those will be in order before the main bend !

Happy building all ... weekend away now to L?beck on the Baltic coast with the Family...happy Oshkosh'ing to those attending....