Ch. 8 - Rollover structure - part 2

Rollover outer recesses (11.0 hrs)

Since the longerons were never designed to support a true rollover assembly, and mindful of the issues I have had in the past with the landing gear brackets, I decided to add 3 plies to both sided of each longeron for strength, staggering them by 1” (2.5 cm), like the wing spar cap, for flexibility.

Unfortunately this meant digging more blue foam out of other places I thought I was done with.

While this sounded like a great idea at the time, in hindsight I should have done as Mike did, by glassing the fuselage first, cutting through the skin to install the outer plates, then patching it up.

Mike's neat roll bar

Because I wanted to avoid cutting the outer skin, I ended up complicating things, and making more work for myself. 

Nevertheless, here’s what I did...

Outlining the area to be cut

This tearing down has got to stop, if I am to make any progress!

Area sanded to remove any old micro, and provide a clean future glass/glass bond.

Glassing the inside of the longeron required more trimming of the front seat. 

More tearing down :-(

The structural strength of this juncture had already been compromised by the two cuts I did last week, when I separated the top of the seat from the longeron. 

The whole top 2” of the seat are basically free floating now, and will probably be cut off later as well to reduce weight.

Staggered reinforcement BID layups

BID applied and peel-plied

To make life easier later on, I decided to contour these recesses at this time, micro all sharp edges, and add 1 ply of BID over the top to hold it all together, until the next day.

Shaping to ease later layups in this area

Microed the hard edges, and slurried where BID will go

One single layer of BID applied to hold everything nice and smooth until outer skin layup

Peel-ply over BID

Same on right side

Peel-ply removed the next day, and hard edge sanded to a nice transition with the longeron top

This recess will house the outer plate and nuts of the removable roll bar

As you will see in the next post, this approach worked out beautifully, and I had no issues dealing with fiberglass not wanting to stick in the corners the next day, while glassing the whole fuselage.

Finally, I’ll share my overcomplicated and non-final sketch of how I planned to deal with this area of construction.

A rough sketch of the proposed layup. I did say it was overcomplicated!