Allegro Lite Build Part 7

I've added another two layers of 160g glass to the fuselage tonight and while that is curing I started with a dry run of the two tip panels components. Quite intensive labour having to very delicately sand the correct angles to the cross grain shearwebs so they butt up to the ribs at the correct sweep. Everything seems to fit nicely according to the plan.

Below is a closeup of the carry through strips I made previously. Next I'll probably get sticky doing the actual building of the tip panels.

Allegro Lite Build Part 6

Those folks on the MGASA group would know that I've been working on the second fuselage that I want to use for the electric version I intend building. It's been quite a learning process as I've never done moulding before.

Below are the moulds on loan from Eugene. It is not the standard AL fuselage but what I like about is the space compared to the original. It has an extended nose so I should get away with less noseweight in the end.

And this is the end result. The layup is a 45g outer layer, some carbon tow and then a 160g inner layer. The parts (untrimmed) weigh 52g up to this point. The fuselage looks and feels a little on the flimsy side so I'd probably lay up another layer of 160g on the inside. Painting will add another couple of grams in the end.

Allegro Lite Build Part 5

I eventually got some building time again in this stupid schedule everybody calls the "Rat Race".

This little contraption is a jig I made to manufacture the bent carbon carry through strips. The carbon cap strips being ±0,7mm thick does not bend at an acute enough angle, therefore the need for the jig. And this is what came from this little excercise.
Cut into strips this is where they fit in the spar system of the wingtips. Note the piece of hardwood added to the balsa cross grain shearweb that will prevent any tendency for crushing in this area.

Allegro Lite Build Part 4

The fuse I got was very light and a little flimsy. To make sure I don't crack it on the first dork landing I decided to reinforce it with some carbon, especially around the wing seat. Some 12K carbon tow was laid underneath with some 200gsm carbon cloth laid on top.

Allegro Lite Build Part 3

The Allegro requires a fair amount of pre-pregged carbon strips, none of which come with the short kit. I decided to make my own. The commercially available strips taper in thickness towards the tip panels which I didn't bother doing.

The uni-directional carbon material comes from AMT. The roll I got is 300mm wide. I cut this into four 75mm wide strips. Next you need to find a flat surface to work on. I scrounged two pieces of 40 mm thick bullet proof glass from a revamped bank that work perfect for this. Next step is to wax up a strip of mylar. Then cut the carbon material to slightly wider than you require. Mix up some epoxy and pour it on the carbon. I then used a hard roller to make ensure the carbon is fully saturated. Then lay on the next layer of carbon and repeat the rolling process. I had to lay four strips of carbon to get the desired thickness of ±0.7mm.
Once you're happy that the carbon has been fully impregnated by epoxy take some paper towel and blot up the excess epoxy by rolling with the hard roller again. This takes care of any unneccessary weight.
Only thing remaining is to lay another strip of waxed mylar on top and to place the other glass plate on top to ensure your strips come out perfectly flat. With the glass plates weighing easily 10kg each there is no need for extra weight on top of this "sandwich".
And the finished product...... Voila! Cutting the carbon into smaller strips is the next challenge.

Allegro Lite Build Part 2

I started out with marking out the hatch opening on the fuse and cutting it out. The fuse came with a seperate hatch cover which fits nice and flush with the fuse. I'll probably end up securing it with a spring loaded carbon rod which you epoxy to the hatch cover ala Xperience Pro style.

Allegro Lite Build Part 1

I bought this "short kit" ages ago and only recently got the itch to actually build it. I bought the kit from Eugene du Plessis who used to fly at VMG with Gert Nieuwoudt. The rib kit and boom come from Laser Art and the fuse is Eugene's own design.

I am quite a slow builder but I'll try and keep the blog updated with my progress. The Allegro is quite an intensive build. The Allegro (AL for short) is basically the 2m baby brother of the 3m Bubble Dancer, both planes designed by Mark Drela of the Supra fame. Look at the Charles Rivers site for more info.

For starters I am going to build the pure thermal plane but plan on building a second "E"-version fuselage specifically for F5J.

My newest acquisition

I eventually decided to splash out and buy myself an Xperience Pro fro Nan Models. Once I've stopped fondling it I'll try and put it together to see what it flies like before the team trials in September. The build quality is absolutely superb!

This bird's eye view of our "South" field is courtesy of Google Earth. I believe the owner, Charles, has accepted an offer on the ground to be developed so we may end up on our old field of a few years ago as the current "North" field will soon be planted with lusern again. I'm sure Paul will keep us posted....