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AUDAX

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Re: AUDAX

Message non lupar Bloodhound » 12 Mar 2015, 18:54

I started working on the stabs by preparing the ribs supporting the servo and incidence adjuster. To make sure these will be secured properly, i added small pieces of 1.5mm plywood to reinforce the liteply locally. I drilled the holes and temporarily attached the adjuster and servo using wood screws.
Image Image

Baking paper is used to keep the stab jig from sticking to the building board. CA glue doesn’t penetrate the baking paper, and the jig is attached to the board using pins. There’s no need for printed drawings to assemble the structure; all i had to do was tracing 2 perpendicular lines on the paper, align the first 2 members of the jig with these lines and everything else is self-aligning.
Image Image Image

I didn’t want to rely entirely on the ribs to achieve the proper curvature of the leading edges, so during design stage i also added a horizontal former which will help bending the leading edge with improved accuracy and perfect symmetry between the 2 stabs.
Image Image

To make the stab structure easy to detach from the jig, the ribs are attached to their supports only in a few points. To prevent any glue running from the joints to accidentally flow into the small spaces between the ribs and their supports (thus making the structure difficult to detach from the jig), all rib supports have semi-circular or oval cut-outs situated directly below the joints. I hope the picture below explains this better:
Image

A few more pictures showing the assembly process:
Image Image Image Image Image Image
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Re: AUDAX

Message non lupar Bloodhound » 17 Mar 2015, 18:43

Adding the rib doublers:
Image Image

Finished stab structure:
Image Image Image

Adding the fiberglass sleeve:
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Detaching the stab structure from the jig:
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Sanding the leading edge following the airfoil shape:
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Preparing the upper surface skin, using 2mm balsa:
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Attaching the upper surface skin to the stab structure:
Image Image Image

Sheeted stab structure (only upper surface for now):
Image Image
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Re: AUDAX

Message non lupar Bloodhound » 21 Mar 2015, 18:45

Adding the balsa block for the control horn and the wood block for the stab retaining screw:
Image Image Image

Sheeting the stab lower surface:
Image Image Image Image Image Image

Adding the trailing edge:
Image Image Image Image
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Re: AUDAX

Message non lupar Bloodhound » 25 Mar 2015, 18:05

The 6mm balsa leading edges are quite stiff and it would be very difficult to bend them following the shape of the stab. I had to soak them with hot water (which makes them a lot more flexible) and let them dry overnight in a curved position.
Image Image

It was now quite easy to attach them to the stabs:
Image

To shape the leading edges accurately, i improvised a tool to help me mark the centerlines on the balsa strips. By shimming it with tape at the bottom and lightly sanding it at the top, i calibrated its height to leave a mark precisely at the centerlines of the root and tip ribs.
Image Image

After some careful sanding, the result looks like this:
Image Image Image

Assembling the stab tip blocks and attaching them to the stabs:
Image Image Image

Shaping the stab tips:
Image Image

Progress on the stab so far:
Image Image
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Re: AUDAX

Message non lupar Bloodhound » 29 Mar 2015, 16:27

Separating the elevators:
Image Image Image Image Image

Preparing the balsa hinge lines:
Image Image Image Image

Attaching and sanding the hinge lines:
Image Image Image Image Image

Attaching the stab root balsa block. This will be sanded later to fit the fuselage:
Image Image

Weight and progress on the stabs so far:
Image Image
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Re: AUDAX

Message non lupar Bloodhound » 03 Avr 2015, 18:06

With the stabs almost done it's now time to move on to the wing assembly.

All the wing ribs are made of 2.5mm balsa with the exception of the root rib which is made of 3mm liteply. The ribs supporting the wingtube have 1.5mm plywood doublers to reinforce the balsa locally near the wingtube holes and also to connect the 2 spars. This helps transmitting the loads from the main spar to the carbon tube and distributes the loads more evenly through the structure. The root rib also has a blind nut for the wing retaining screw and a doubler near the leading edge where the incidence adjuster will be placed.

The first step was preparing the first 5 ribs by adding the plywood doublers, blind nut and also slightly sanding the wingtube holes to match the diameter of the sleeve.
Image Image Image Image

The jig assembly starts at the trailing edge which is made of 2 parts so i had to make sure it is perfectly straight.
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I also had to check the perpendicularity of the member near the root rib. Together with the trailing edge, it will define the alignment of all the other parts, so it is important to make these 2 perfectly straight and perpendicular to each other:
Image

All the other parts are self aligning:
Image Image

Adding the ribs:
Image Image Image
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Re: AUDAX

Message non lupar Bloodhound » 09 Avr 2015, 20:13

More work on the wing assembly:
Image Image

Adding the curved trailing edge:
Image Image

Adding the aileron end ribs and hinge line former:
Image Image Image Image Image

Adding the leading edge formers:
Image Image Image

Assembling the servo box:
Image

Progress on the wing so far:
Image Image
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Re: AUDAX

Message non lupar Acromaster » 10 Avr 2015, 01:11

Very nice work!
I do appreciate.

Olivier
In Texas, everything is bigger !
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Avion: Mythos 125
Moteur: Hacker A60
Hélice: 19"
Carburant: LIPO
Emetteur: JETI DC-16
Récepteur: JETI
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licence: AMA

Re: AUDAX

Message non lupar Bloodhound » 10 Avr 2015, 07:46

Thank you Olivier!
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Re: AUDAX

Message non lupar Bloodhound » 18 Avr 2015, 15:30

Bending the 6x6mm balsa stringers with water:
Image

I used the shear webs to determine the correct position and distance between ribs along the spar:
Image

Attaching the main spar balsa stringers:
Image

The ribs near the tip of the wing are too thin for the 6x6mm balsa stringers, so i replaced them with a balsa former:
Image

Adding the 6x6mm balsa stringers for the wingtube spar:
Image

Adding the wingtube sleeve:
Image

Adding the shear web:
Image Image Image

Completed left wing structure:
Image Image Image
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Re: AUDAX

Message non lupar claudecuinet » 19 Avr 2015, 07:18

Hello Alex

Awesome job !
You did composite wings for this plane as shown on picture below. Why doing scratch build wing

Image
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Avion: HARMONIE turquoise
Moteur: YS 175 CDI
Hélice: APC 20x10,5
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Re: AUDAX

Message non lupar Bloodhound » 19 Avr 2015, 07:57

Thank you Claude !

The first set of composite wings was very heavy, around 500g/wing. Maybe it was good enough for a few test flights but not for competition flying.

As i said before, all the composite work was done together with a friend of mine who is specialized in composite work and has a workshop. He was very busy molding a jet and a few other projects this winter so i didn't want to bother him with another set of composite wings. Instead of just waiting until he finishes his own projects, i decided to build the balsa structure wings, stabs and rudder and try to get the plane in the air this summer.

We are not going to give up on the composite wings, just need more time to achieve a good weight.
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Re: AUDAX

Message non lupar Bloodhound » 20 Avr 2015, 14:19

Right wing structure completed:
Image Image Image Image
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Re: AUDAX

Message non lupar Bloodhound » 27 Avr 2015, 16:42

Wing structure detached from the jig:
Image

Sanding the leading edge former following the shape of the airfoil:
Image

Sanding the excess glue from the shear webs:
Image

Preparing the wing skin:
Image

Wing structure and skin attached using polyurethane adhesive and pressed together in the jig:
Image

A few images of the result:
Image Image Image Image Image
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Re: AUDAX

Message non lupar jclaude » 28 Avr 2015, 13:45

Wahouw! Cool structure.
jclaude
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