First off I wanted to share a link to the site of a guy building a Berkut in Japan. He has lots of pictures of his build and more than I have been able to find of the Berkut construction.
Next step was to install the F1-3 bulkhead. When I had temporarily put it in its place I checked the clearance as the gear retracted. I had a point of contact to that will require some modification.
In this pic you can see how the gear is contacting the bulkhead. I was going to just put a relief in the core but decided to go a different route so I would have lots of clearance. Since I haven’t completely worked out how my gear door is going to end up I wanted to make sure I had ample room. What I ended up doing was making a slice in the back face of the bulkhead and bent it forward to make a flap. You will see it better in pics to come.
All the related surfaces were sanded and cleaned and the metal bits taped up.
I then smeared peanut butter on the bonding surfaces, no its flox 🙂
The bulkhead was located and the fillets were tooled with flox. I cleaned up as much of the excess flox as I could.
The forward radiuses were done in the same manor as the back side. Here you can see how the flap that I made for clearing the landing gear is positioned forward.
The two plies of BID are being laid up on the front of the bulkhead. Here you can see the flap a bit better.
All corners were taped and peel plied.
The back side of the bulkhead was then taped. This is a view of the extra space gained for clearance of the landing gear.
All edges were taped and peel plied.
The epoxy at this point was just start to jell so I was able to remove the clamps and do the inside of the NG 30’s to the bulkhead. I wanted to install the F4.1 so I had to pull back some of the peel ply that I had already applied. The resin was jelled enough that if I had just pulled it off the laminate probably would have come with it or at least made a mess of it. I used my heat gun to warm up the surface and the peel ply came off like it was just wet out.
The bonding area on the NG 30s were given a gooping of flox.
I had already glassed and cured a layer of glass on the back side of the F4.1 and had previously shaped it also. I wanted to bond it on and glass it at the same time. So what I did was take some flox that I had mixed up earlier and put it on the for corners. It was already jelling so I had to warm it up with the heat gun to soften it to get it to stick. The rest was fresh mixed flox. I then gave the four corners a warm up with the heat gun and put it into position.
Here it is in position and lots of squeeze out of flox.
I used a fiber glass rod to tool the fillets on the inside. I had to be careful not to disturb the glass tapes as they were just layed up.
After a few minutes the flox in the corners cooled down and returned to their jelly state. It was now held in place and with uncured resin so everything will still remain a wet on wet layup.
The two layers of BID were applied over the F4.1 and overlapped 1″ onto the NG 30s and peel plied. The other tapes were warmed up and new peel ply put back over them. That concluded the layups needed on the bottom half of the nose.
I had some resin left over from glassing the bulkheads and did’t want to waste it. The next step will be building the bottom of the nose to match the height of the floor of the fuse. So I used the excess resin to mix up some micro.
I used the micro to bed some styrofoam into the recess along the honeycomb and the NG 30s
Here is the foam wedge with the excess micro cleaned up. The same was also done on the right hand side at the same time. Now it was time to let everything cure up before I did something stupid and bugger up what i just finished laying up.