AUDAX

[fabien drouet]

Good morning,

i put on the picture below what i've seen to save weight. I made many composite wings and i never used so much reinforcement.
Which clothes do you use in your wings ? Glass 50grs/herex/glass 50grs ?

J'ai mis sur la photo ci-dessous ce que j'ai vu pour gagner du poids. J'ai fait plusieurs ailes composite est je n'ai jamais utilisé tant de renforts.
Quels tissus as-tu utilisés dans tes ailes ? Glass 50grs/herex/glass 50grs ?

[Bloodhound]

Hello Fabien,

Thank you for helping me with ideas to save weight. Yes the internal structure is much too strong and heavy (140g) but decided to build the wings anyway as a test. There were also some spaces between the structure and the wing skins, so we had to fill them with adhesive and that added a lot of weight too. I intend to redesign the internal structure and solve all the problems for the next pair of wings.

The layup we used is: 50g glass, 2mm airex, 50g glass. In your opinion, is it possible to use 1.2mm airex instead?

The main spar is made of 6mm balsa, laminated with 100g carbon. The ribs (nervures) supporting the wing tube are made of 3mm liteply, also laminated with carbon. Please let me know which materials you used for your wings.

Regards,
Alex

[fabien drouet]

The layup we used is: 50g glass, 2mm airex, 50g glass. In your opinion, is it possible to use 1.2mm airex instead?

i used on mine: kevlar 60grs/herex2/glass 25grs. I wouldn't use herex 1.2. to save weight we have to pay attention to the quantity of glue used to glue internal structure and to close the mould. We always use too, too, too much glue.

The main spar is made of 6mm balsa, laminated with 100g carbon.

i thing it is too heavy. this spar is only to maintain space betwen extrados and intrados. It is like a polystyrol/balsa wing...

The ribs (nervures) supporting the wing tube are made of 3mm liteply, also laminated with carbon

.OK for first rib and false rib (wich maintains the end of the sleeve).

Please let me know which materials you used for your wings.

for me:
kevlar 60grs/herex2mm/fiberglass 25grs or 50grs.
first rib: honeycomb laminated carbon 93grs
no false rib, only pièces of honeycomb/carbon Under and above the sleeve.
structure for ailerons: balsa 2mm

[Bloodhound]

Thanks Fabien, this helps a lot. Do you have any pictures of your wings with the internal structure exposed?

[fabien drouet]

I'm looking for but it's a little bit old now....

[fabien drouet]

You can find a picture on this thread about construction of an other wing composite
avions-perso/topic1724.html

[fabien drouet]

found photos of my first wing only
https://s.joomeo.com/53fb2a310dba0

[Bloodhound]

Thanks a lot Fabien, this is really helpful. Your wings look great, very nice work.

[Bloodhound]

I attached a few images showing the rudder construction. The internal structure is positioned using a cardboard template. I plan to paint the plane later, after the maiden flight so i have to make the rudder removable. I will use Robart hinges, with a removable carbon rod going through them.

[Bloodhound]

The composite fuselage extracted from the mold is just an empty shell, so i had to add some internal parts for equipment installation and structural strength.

I started with the landing gear support structure; the vertical frames were cut from 2mm plywood and the gear support plate is made of 4mm plywood, all carbon laminated. I added the M3 blind nuts for each gear leg and in the end the structure was assembled and epoxied inside the fuselage.

[fabien drouet]

What is the weight of fuselage ?

[Bloodhound]

As it came from the mold, 690g.

[Bloodhound]

The tail structure was added next. The shape for the formers was taken from the CAD model, printed at 1:1 scale. First i made a cardboard template, adjusted it a little here and there and used it for tracing the formers on a balsa sheet. I noticed that even fairly thick balsa can easily buckle under lateral loads, so i added a few pieces of balsa with the fibers going at 90 degrees relative to the formers. These weigh almost nothing but add a lot of strength to the structure.

The location of the tail structure was traced on the outer surface of the fuselage. Using a light source on the inside, i aligned the formers with the markings and attached them with epoxy and microbaloons.

[Bloodhound]

I added a piece of 4mm plywood for the tail wheel support and worked on a few more structural elements. A vertical balsa frame will be attached behind the cockpit and a horizontal depron crutch with balsa reinforcements will be fitted between the frame and the tail structure.
I also put the landing gear on just to take a quick look at the model.

[Bloodhound]

I also made a balsa tube for the elevator servo extensions to run through. I attached it to the horizontal depron former and in the end all the parts were glued inside the fuselage.