How important is this?

[Esser]

How important is it to fill the gap between the tank flange and the #1 and #3 rib? Is it for aesthetics? Or is it structural some how?

[Dave S]

Esser,

You will likely get various opinions on this one.

One point to consider is what will happen with the #1 rib after the fabric is attached and the shrinking takes place???? Recall that the outboard rib has two braces between the main spars to prevent the fabric shrink from pulling the rib in at the middle and the #1 will have nothing at the rib cap if the gap is not filled/bridged.

Another point to consider is if any motion occurs in the narrow gap between the tank and ribs where the fabric or paint on the fabric may be subject to fatigue....don't know for sure.

I don't know what all the issues might be with the #3 rib except to say that if the whole works is bonded with the tank lip it is probably stronger....like with a monocoque design in a car or other applications where a core is laminated and bonded to a skin.

For sure, there are some aesthetic advantages to filling the gap......other opinions and experiences may shed more light on the option you are asking about. I don't recall this question coming up before so you might be on new ground that has not been explored much.

FWIW....I did bond #1 & #3 to the tank....also drilled holes for the rib lacing at #3 adjacent to the tank.

Sincerely,

Dave S
KF7 Trigear
912ULS Warp Drive

St PAul, MN

[Esser]

I think I will bond them. I was just curious. Either way I will be rib lacing the number one and three so I will have to drill some #40 hole. What is the best way to epoxy this? Tape the top and fill in? Or tape the bottom and trowel it in for a smooth finish?

[Dave S]

Esser,

I am sure this has been & can be done either way. I recall that I used a strip of masking tape on the backside, hysoled the gap then sanded and finished off with superfil.....maybe a bit AR but I wanted it to look smooth.

Sincerely,

Dave S

[AirFox]

Josh, You will need a larger hole than #40 to get your curved lacing needle through. Don't ask me why I know! Good luck.

Scott

[Dave Holl]

I did the same as Dave S and it worked very well.
Dave