Ultimate-Jets

 

I have just received one of the first Aviation Design Scorpion Mk2 produced from the new Eastern Europe facility. The main difference from the previous Scorpion lies within the moulding technique. This model uses drilled airex that enables a very high level of resin absorption in the vacuum process. The resulting layup looks very close to prepreg and is very light.

I will detail the assembly process and give you as many insights and tips as possible.

 

But first let's have a look at the kit, and the quality of the plane.

 

 

Here is a picture of the kit in the box. It is quite compact but well laid down and well protected. I did not get any damage during shipping.

 

 

 

All the composite parts show a high gloss finish. The leading edges are covered with a grey sticker reproducing a high lift device.

The moulding joint is on average 0,4 mm thick.

 

The wing:

 

 

 

The anti rotation pins are well glue and embedded in a hard wood block that goes from the lower to the upper laminates.

 

 

 

The flight control spar and rear wing spar are made of thick balsa and well glued. Not a single gluing discontinuity was observed on the entire plane. Some areas show some glue add-on which is a sign of proper quality check.

 

 

 

The flaps, ailerons and rudders are live hinged with a piece of hinging nylon fabric. The live hinging is well done and the fabric do not exhibit any sign of cutting.

 

 

 

The rear fuselage looks really gorgeous with a very thin joint line.

 

 

 

The formers are either made from liteply ( not structural formers ) or aero grade Finnish birch plywood ( structural formers like the main wing and rear stabilizer-fins former ). All glue jonts were perfectly made.

 

 

 

The turbine rails are made of aero grade plywood and feature a vertical stringer. The rail has a series of tabs that are glued into the stringer. This results in an incredibly stiff engine mount. Note the drilled airex that shows very well on this picture and the quality of the rail plywood.

 

 

 

Here is a view of the rear stabilizer assembly. A bronze tube is embedded into a plywood box that is filled with a mix of resin and microspheres. An IC board finished the setup for maximum stiffness. This former is made of aero grade ply.

 

 

 

The fuselage hatch is well moulded and rigid. The hatch joint is thin. The speed brake is CNC pre-cut on the top of the hatch and a carbon fiber patch reinforces this area.

 

 

 

The nose is made the same way with a very ligth structure.

 

 

 

 

The nose gear plate is made of aero grade plywood with liteply vertical formers. Inserts are designed to setup the Behotec gear quickly. The front vertial former is reinforced by a glass fiber tape at its bottom.

 

 

 

 

 

The nose to rear fuselage assembly is snug and nice. There is almost no clearance between the two parts.

 

 

 

 

The thrust tube is made by Ilja Grum in Germany and feature a very light aluminium outer wall.

 

 

 

I borescoped the internal structure of the wings and fins. Here are the pictures:

Wing leading edge gluing.

 

 

 

Wing intermediate rib gluing.

 

 

 

Intermediate rib to wing tube gluing. This is the end of the wing tube. The hard wood blosk increases the effort spreading surface.

 

 

The wing root gluing at the wing tube.

 

 

 

There is a small zone without glue. This is the only spot where glue is missing on the entire plane. Not bad at all...

 

 

The fin tube is glued on a hard wood spar. The inner one goes all the way to the top of the fin. I could not get a picture of it with the borescope because of the poor optical quality with the mirror.

 

 

The fin leading edge gluing is perfect, just like the other flying surface.

 

 

I am going to the Xray machine tomorrow and will have some pictures of the stabilizer ( if the customs officer allows me to make such a picture on his machine ). 

Here are a few pictures of the plane just dry fitted in the workshop. All the elements fit perfectly and it took me 3 minutes to assemble the shell.



And the best for the end. The mass estimate.

I scaled all the components as followed.

Left wing: 510 grs

Right wing: 522 grs

Left fin: 170 grs

Right fin: 155 grs

Left stab: 190 grs

R stab: 198 grs

Rear fuse: 2343 grs

Nose + canopy: 924 grs

Thrust tube: 265 grs

Hardware + pilot: 400 grs

Wing tube: 210 grs

Fuel Tank: 220 grs

Servos and receiver: 360 grs

Batteries: 350 grs

Merlin VT80 all up and 5 min of fuel: 2400 grs

Behotec gear: 900 grs


Total: 7720 grs for a takeoff thrust of about 8 kgs with the Merlin VT80...

Written by Olivier Nicolas — April 27, 2013

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