So here is how we do it: We draw some concentric cirlces on really slick plastic (like a garbage bag, which would work fine I bet) and cut the plastic into a circle. Then, we use that as a template to cut circles of carbon-fiber! After we cut the outer circle, we simply do the same for each inner circle, cutting down our blue plastic template, and cutting progressively smaller pieces of carbon fiber. When done, as you may be able to guess, we have 4 circles of carbon fiber, each smaller than the other. These are the pieces of carbon fiber that will overlap the cookies to hold them in place and much-strengthen the fuselage at the belt-attach point.
Now we get some resin and catalyst:
...and stir it up good. From this point, we have maybe 60 minutes to do what we are going to do before the resin hardens.
So what are we going to do? We are going to put some resin on this slick plastic, for starters.
...and brush it out smooth into a nice thin layer of resin.
Now, as you may guess, we throw down the biggest circle of carbon-fiber and get it nice and wet with resin!
And we get it nice and wetted out with a brush, then squeeze out the extra resin with a squeejie... we hate extra reson because it weighs us down!
Then, having done the biggest circle, we do the next smller circle of carbon fiber on top!
And the thrid one! For each layer, I add just enough resin to make it all wet for the next layer, add the next layer of carbon fiber, and squeeze out all the extra reson with the squeejie. I squeeze REAL HARD to get out all the extra resin!
Then finally some plastic on top! Now a final squeeze to get out the last of the resin that I can.
Oh crap I am an idiot I forgot the peel-ply! The peel-ply must be the final layer becuase we will rip this off AFTER the job is done to pull that final bit of reson out of the airplane! You see, our squeezing will pull a lot of resin up into the peel-ply. Then, when the job is done, we will rip the peel-ply out of the airplane, and it will of course bring that resin right out with it! And into the nearest trash-can, where it belongs. (not in the airplane, adding weight!)
OK now with the peel-ply in place, we squeeze out again. You notice that I am doing TWO installations here. The left and right passenger seatbelts.
We now punch a hole in the middle where the screw will pop through!
And we cut away the edges so we have perfect Chuck Norris pancakes: 4 layers of carbon fiber and resin with some peel-ply on top! (white stuff)
These pancakes are flexible like wet cloth, and within 30 minutes or so will heat up and harden, bonding to whatever they are touching at the moment.
Now we wet up the airframe with resin where these things will mount, which will guarantee a really good bond between the carbon fiber circles and the fuselage inner skin.
And now we throw the pancake on top of the cookie!!! You ccan see that there is no way that cookie will be able to escape from the airframe now with all those layers of carbon fiber on top, and you can also see that we have ode than made up for the structural loss we incurred when we drilled out a hole in the inner fuselage skin!
Ah yes. Brushing the pancake into place on top of the cookie, securing it forever.
And just because I like to do a PERFECT job, I brush some more resin onto the peel-ply so if there are any microscopic dry spots in the carbin fiber, the resin will seep into them to complete the bond to 10 effectiveness. When the whole thing drys and I yank out the peel-ply, it will bring with it the extra resin.
Done! We will yank out the peel-ply tomorrow when the carbon fiber is 100% set up.
Umm.. the view from the door shows both right-side belt mounting points in place, where what you really see is the seatbelt.
Now you pull off the peel-ply, wich takes out the annoying, useless, heavy resin that you brushed and blotted out to the top!
And this is what is left behind.
The aircraft structure was weakened by putting a hole in the inner skin, but that strength was made up for by the 4 layers of carbon fiber you see here! And, that seatbelt attach bracket will not be pulled free in an accident!
OK so there you have it! Now all I have to do is crash the airplane really hard to make sure they work!