MIRO 2

[Rod]

Hi everyone. Unemployed for the time being so a new MIRO F3A is underway. I will incorporate some changes and use some new techniques. This model will be all painted as well.
Rod

[Rod]

I had to make a new UC leg mold as I melted the last one so I wont do that again. This time I am also making the legs 15mm longer for a bit more ground clearance. I will also use less carbon as the first ones were way strong. The mold material is 100mm high density blue foam an offcut from Weta workshops, it is available from some place in Auckland I could find out where if anyone is interested. The 3 mm sheet offcut is to form the dams for a neat molding. I have glued on a sheet of clear plastic with 3M77 and have used waxed paper to control its application and make sure it sits down in the corners properly.

[CSpaced]

Subscribed.

I'm looking forward to watching another one of your builds, you are da man when it comes to scratch building composites!

[Rod]

Layed up the cowl today. This is the most tricky part due to its complex shape so I wanted to get it out of the way first. On the first model I had to add material afterwards to stiffen the part as I only used 1 layer of 75 gm glass and one layer of 75 gm Kevlar. This time around I am using S glass instead of Kevlar. S slass is 30% stronger and 15% stiffer than the usual E glass, I can feel the difference when cutting and handling it. The layup is an outer layer of 75gm E glass (for a nice surface) then 2 layers of 120gm S glass. You can also see I have put in a fillet of thickened epoxy in the corners of the flanges. I put the thickened epoxy into a ziplock bag and cut a little hole in one corner the squeeze it out like cake icing then smooth it off with my (gloved) finger.
Rod

[CSpaced]

Looks like it will be a good solid part.

[Rod]

Pulled the cowl out of the mold with some difficulty. Obviously didnt put enough release agent on, however no damage was done. It weighs 85gms and is really strong and stiff. The prototype weighed 58 gm out of the mold and needed reinforcing, it ended up weighing 90 gm finished.
Rod

[Rod]

Here is the canopy. Again quite difficult to get out of the mold. For the fuselage I think I am going to change over to the new mold release I have been playing with on a DLG fuse. The weight of the canopy is 108gm as opposed to 73 on the original which needed extra reinforcement and ended up 98 gm finished. This canopy is really strong and I may have overdone it a bit. Between the canopy and cowl there will be an increase of about 50gms.

[CSpaced]

Looking good Rod, have you thought about selling these as kits? For instance just the major parts as they come out of the molds?

[Rod]

Hi Chris
I might let my arm be twisted to do parts for people. But it isnt really economical for me to do it though. I would rather use the time to do my own stuff as I wont have time when the next job starts up.
Rod

[Rod]

Have started on the rudder. I didn't like the hairspray method of sealing the insides of the skins so I am using non tautening nitrate instead. I tinted it so I could see the coverage. I cut a sharpie open and soaked it in the nitrate. I put on 4 light coats. I put a piece of untreated wood in the pic to show the colour difference. I forgot to weigh them before and after but I will on the stabs. You can see I lightened the LE reinforcement.
Rod

[Rod]

I use a jig to glue on the LE sheeting. I use PU glue for this and cyno to glue the 2 pieces of sheeting together in a right angle.
Rod

[Rod]

Here is the rudder in the vac bag. I mixed micro balloons into the epoxy to tint it (red) and to make the resin go further. I put about 1/1 micro balloons in and the mix was still runny. The way I figure it the epoxy only needs to be as strong as the foam it is holding on to. I will be cutting out a block of it for the horn support so I will be able to test it.
Rod