Schweizer SGU 1-19 avec fuselage en tube

[Claude Moinier]

Bonjour,

Suite avec la brasure des montants avant.



Préparation des deux premiers tubes du carénage. Le cintrage correct des tubes c’est avéré plus facile qu’anticipé



Les longerons latéraux du carénage sont brasés ainsi que le support pour les tubes du museau qui donneront la forme caractéristique à facettes du nez. Le fuselage commence à être volumineux mais reste raisonnable.






À bientôt,

[VincentB]

On voit qu'il n'y a rien de vrillé, ça file droit

[Claude Moinier]

Bonjour,

Enfin du temps libre pour continuer la construction. Ici les lisses hautes avec leurs entretoises à l’arrière de la cabine.



Pour se faire plaisir, présentation du tableau de bord (en papier !).



Sympa, la cabine commence à prendre forme.



Vue depuis le montant de dérive. Ça fait beaucoup de tubes !



À bientôt,

[Fotor]

Claude, any progress in your project??

[Claude Moinier]

Bonjour à tous,

Après une longue période d’absence sur le forum, enfin reprise de la construction du Schweizer 1- 19. Le nez du fuselage est maintenant achevé et reste à poser les lisses basses en tube de 3mm. Des entretoises seront brasées entre les lisses et les croisillons pour la mise en forme et rigidité.


À bientôt,

[VincentB]

Bonjour Claude, ça fait plaisir de te revoir sur le forum
Pour l'empennage tu penses finalement le faire en alu ou en inox?

[Claude Moinier]

Bonjour Vincent,

Finalement j’ai découvert que sur certaine version le plan fixe vertical et la dérive étaient fabriqués en bois, ce que je vais faire. Concernant le plan fixe horizontal et le volet de profondeur, tube inox avec nervures en bois bien plus facile à maîtriser que l' aluminium.

A+

[VincentB]

Et surtout l'aluminium ça n'a pas de tenue au choc. Stab inox/bois ce sera collé?

[Claude Moinier]

Vincent,

Sur le stab en inox/bois les nervures seront collé à l’Araldite chargé de poudre pour faire léger. Les charnières du volet de profondeur seront bien sûr brasées sur les tubes comme sur le grandeur!

[bocorvin]

Hello everyone,

Claude is a very good friend and member of the same aeroclub. Also the builder of this beautiful fuselage. He got grandchildren, which takes a lot of time and the fuselage of the SGU 1-19 just rested . I thought that was a pity (so nicely built) and offered to finish the glider. Claude agreed and he brought all the stuff of the Schweizer to me. I admiring his fuselage once again and started to read how this glider was constructed.
I write it in English, French is still to tricky for me....
Besides the fuselage of tubular steel, I think the empennages were made of of metal and wings of wood. Maybe there were other versions, I am not sure. Claude also brought a lot of info and drwings, very good!

I started with the empennages. After the necessary research, I presumed that they were made of steel tube for the LE and TE and the ribs of tapered "U" profiles of bent metal plate, see photo of the original.


The main spar of the fin and rudder are also made in this way
I decided to imitate these ribs and spars by imatating the “U “ profiles of 0.4mm plywood with battens in the corners. Because this "airfoil" does not exist in Devwing, I couldn’t draw it digitally. So I started with strips of plywood directly on the drawing.

After the battens (2x2mm) were glued to the plywood and the glue was dry, I cut away the excess plywood and glued other strips on it, to imitate the U profile

I didn't have a 3mm stainless steel tube lying around and took 3mm aluminium tube, through which I wanted to pull carbon rovings with epoxy later I pulled rovings (4X) through the aluminum tube continuing on the bottom rib. (See the following report of the horizontal stabilizer)

Before I am putting the diacov on, I want to spray the whole thing in the same color, just as the real thing.

The horizontal stabilizer,
The construction of this resembles the fin and rudder, only the main spar is a tube, with struts, see the original drawing


The hinges are small tubes welded onto sleeves, which in turn are welded over the main tube. I imitated this by soldering a 2.5mm brass tube to a 6mm stainless steel tube.

With a diamond disc I slit the tube at the back to get it to fit. Then I sawed off pieces of 5mm and slid them over the 5mm main spar tube.

A nail is the hinge pin for the time being. For the rudder horn I soldered a tube perpendicular to the main beam.



For the rudder horn I soldered a tube perpendicular to the main beam. I used my working light to temporary fix it.

The ribs (of the original) are also made of bent metal plate, forming a “U “ and are therefore also straight, but tapered. Because they are very small, Adri milled them out of 3mm sturdy plywood. I glued them to the stainless steel tube with thick cyano.The TE and LE are made of 3mm aluminium tube, which is easy to bend. Then I pulled 4 rovings through it with a double thin flexible steel wire

The complete stabilizer


and put on temporary for the photo on the fuselage.
.


the original




Finally the weather is getting better, so I think the progress will not be fast this summer…

Vincent (DB)

[VincentB]

Bonjour Vincent, c'est super que tu ais repris la superbe construction de Claude, commencée il y a 13 ans déjà, que le temps passe vite....
on va suivre ça avec intérêt

[bocorvin]

Hello Vincent,

Thanks for your encouraging words, Claude did such a good job, I am glad to go on with the build

Vincent (DB)

[bocorvin]

This week I started again with the Schweizer.
With the parts I got from Claude, were also the ribs of the wing. It took some figuring out how the wing should be constructed, because this wing is different than I'm used to. It has a very small D box, the torsional stiffness comes from two substantial beams that, along with two struts, form a rigid structure. To make it strong in the horizontal plane, the original wing has cross bracing of steel wires with metal tubes to absorb the compression of the cross wires.




I chose a slightly simpler solution by replacing the steel wire with 3X3mm spruce battens.

The tip list is also a bent tube, which was screwed to the wooden beams with metal strips. I had accidentally extended it to the LE, I didn’t look closely to the original.





soldering the metal strips, looking for some support when soldering!





So, I cut the tube and removed the front piece. Instead, I put a balsa block that I shaped and sanded.







The TE is constructed from plywood on the top and bottom, filled with balsa. I also threaded a thin steel wire through it, and I'm going to fill that front section with thickened epoxy to make it a bit sturdier.








Next is the other wing, and then finishing both wings after a trial fit.

Vincent (DB)

[bocorvin]

The other wing went a bit faster, gluiing all the gusset plates and temporarily mounting the fittings.
Adri CNC milled the fittings from epoxy sheet, which is much more precise than I can make by hand. Then the struts, I wanted to use stainless steel tubing for that, but that turned out to be much too weak. The struts are subjected to pressure, especially when landing, and I had to come up with something else. I ended up with a composite wood/carbon strut. First a kind of wooden U-profile



made of spruce slats and a strip of 0.4mm plywood. In it a few wet rovings, on top of that 8 double rovings soaked in epoxy, which I pulled through 2 pieces of 4mm stainless steel tubing, another number of rovings and covered that. Ending up with a 5X5mm carbon rod. After hardening on the “open” side another strip of plywood and that whole thing already roughly profiled.





The horizontal stabilizer attachment still had to be done, I came up with two epoxy "lips" that fit under the strip on the fuselage and 1 central nut through the rear frame tube.






Struts will also be placed under the stabilizer, they will come later. Now that the wing struts were ready, it could be put together for the first time, (mettre en croix) always a nice moment :











Vincent (DB)