Fokker FG-2 - Congrès 2017 Vauville

[Walter]

Hi Vincent,

...very interesting project - I will follow!

3784 actions.... and nobody can see this after covering....

So - I would suggest - make one ore two more for demonstration...

...hope to meet you in vauville



Walter

[bocorvin]

Hi Walter,

Thanks for the . Luckily you can see the ribs at the "Expo fuselage!", but the main reason is the translucentcy of the wings, with massive ribs they would look very different (I think )

Vincent

[Mad Doc]

Hallo Vincent!!!!
Endlich habe ich es geschafft mir Deinen Bericht anzusehen, was für eine schöne Arbeit!!!
Ich bin sehr gespannt auf Deinen weiteren Fortschritt, liebe Grüße,

Christian

[bocorvin]

Hello everyone,

Back from Polsa and our holyday I started again with the wings.
I liked to make the wingspars thinner, 4mm instead of the 8mm as planned, with internal crossbracing, as I discovered on the photo (with the FG 2 on crates). First I made a full size drawing of the wing.


I made mainspars from 4 X 4 mm with a ply webb and vertical from 3 X 2mm.




When I got them finished they appeared to be very flimsy. I can imagine, that combined with the crossbracing it would be just strong enough, but very vulnerable. In the end I decided to go back to a bigger spar. Because the wing must not be stiff in torsion, I opted for 4 X 8 mm top and bottom with a single 1 mm ply webb.

This was much better! I also choosed to have the wing divided, in one piece is too impractical. As wing joiner for the main spar I took a steel strip 10 X 1 mm and for the rear spar a 3 mm steel rod. In the centre part of the wing are a lot of attachments; on top the struts with fuselage, and at the bottom the landing skid. I took M 4 bolts bedded in epoxy with filler and some carbon reinforcement. I greased the M 4 bolts a bit, so I could take them out when the epoxy was set.







(The balsa at the ends is just to prevent the epoxy for flowing out, it can be taken away easily.)



All the stuff needed for the wings..

The central lower part of the wing.

Putting all the ribs on the spars, a very quick job compared with making of the ribs itself!

One wing! To my big relief it was in horizontal plane sufficient stiff and stiff enough (for a biplane) vertically.

Moment of truth: the wing is easily warped!

Next thing is the upper wing.
To be continued.
Vincent.

[VincentB]

Encore un sacré travail de fait, bravo Vincent

[michel]

belle structure, c'est quoi comme profil ?

Michel

[bocorvin]

Merci Vincent et Michel pour les comments encouragieus!
Le profil est Eppler E174.
The weight of the wings at this moment is 640 grams, I think the whole plane will be about 3000 to 3500 gramms. Gives a wingload of 22- 26 gr/dm.

Vincent

[bocorvin]

Hello everyone,

Erstens, Christian , danke fur dir kommentar, es war schon lange da, befor wir zu hause waren, Ich war vergessen darauf zu reagieren.

This week I assembled the top wing,




I'will make the internal crossbracing only cosmetic, because I made the girders a bit heavier.



Top and bottom wing together;




Laminated the wingtips out of two 2mm X 3mm spruce .


Both wings



Now I am going to finish the wings and start with the fuselage.

To be continued.

[Frédéric]

Salut Vincent !

C'est magnifique ! Très joli travail !


Amicalement
Frédéric

[michel]

Magnifique structure,

Michel

[bocorvin]

Merci Frederic et Michel! It is very encouraging
I am waiting for the tubes and puzzling about the fuselage, how did Fokker connect the wood with the tubes etc?

Vincent.

[VincentB]

Que fais tu exactement en tube? tout le fuselage avec les haubans des ailes et les poutres arrières qui maintiennent l'empennage? ou seulement la partie avant du fuselage qui est entoilée?

[bocorvin]

Bonjour Vincent,
Excuse moi, je continue en Anglais, the tailboom, horizontal and vertical stabilizers, wing struts, struts for the skid and the tubing to support the skin of the nacelle are of tube.
The " A " which you can see on the view from above on my plans is from wood, but I think it is interconnected with metal fastenings. In the coming week I am going to visit the "Aviodrome " (a museum) to have a close look of the Fokker Spin (spider) which is displayed there. The Spin is also a bit of hybrid construction, timber with metal. I hope that I understand a bit more of his , don't know how to say, construction pattern? just the way he worked with wood & metal. I ordered the tubes at "tubos capilares", very nice service, hope to get them on short notice.

Vincent.

[VincentB]

Pour des connexions tubes/bois, tu peux braser une tôle de 1mm et boulonner. Le bois peut aussi rentrer dans un tube si ce n'est pas une partie soumise à des efforts.

[bocorvin]

Je ne comprends pas, helas, je ne connais pas le mot "boulonner".
On one of the photo's you can see (guess) how support tubes are fastened to the skid, it looks a bit like this.
The tubes are silver soldered to the "U "plate.


The bolt is M2 , that would be M10 true scale. I guess he connected those quite big timber parts with metal plates and bolts. Its only educated guessing

Vincent

[VincentB]

[bocorvin]

Bonyour a tous,

I started with the fuselage, first the nacelle. That is built of wood and steel. I tried to make a drawing based on the existing plans, photo's, thinking and guessing!




To get a better idea how fokker bolted all that wood together I visited the Aviodrome, the Dutch aircraft museum. The plane I like to see was the Spin (Spider).I was allowed to make photo's of details (thank you!). There is a snag, this was a replica of a replica, I think the basic construction of the fuselage was 90% correct.










As you can see, rather big steel profiles and big bholts are used, I'll try to keep this in mind!
I glued the wooden frame, first out of 10mm X 10mm spruce, but looking at some photo's of the original I changed it 8mmX 8mm.

Laminated the skid, first 3 layers 3mm X 8mm spruce, later one extra layer at the bottom. I drenched the spruce in boiling water before bending. Clamped it without glue together


and put very thin cyano on it, no mess!
Now I had to start with the metalwork. I ordered stainless steel tubes at "tubos capillares", as recommended on the forum and within a couple of days I received a 2m long package, very good service!

I made the supports for the skids an the piece of metal at the nose to connect the 'nose'of the 'A' and later the tubing of the nacelle. It was long ago I used silver solder and it took some time to get used to it.

After using a bigger torch thing went better, but it was sometimes difficult to keep all the parts correctly placed!






Later it will be bolted with M2 trough the wood.

Just to get a better idea to make the tubing of the nacelle, the placing of the rc equipment and the pilots I put it temporary together.

Never built someting like this
My idea is next to make the tubing of the nacelle and a bit later detailing the wooden structure. I am not used in constructing wood with metal and there is a lot of thinking and guessing in it!

to be continued.

[CHAUSSEBOURG]

Very good building and many thanks for all the détails!
Pierre

[de Schaetzen Harold]

Prachtig! Zeer indrukwekkend. Alles is goed nagedacht.
Doe zo voort.
Harold

[bocorvin]

Thank you Pierre for your nice comments and Harold hartelijk bedankt en inderdaad ik moet me soms suf denken, maar dat maakt dit soort projecten spannend!

Vincent

[bocorvin]

Bonjour a tous,

I started with the tube frame of the nacelle, made it from 6 mm stainless steel tube with a wall thickness of 0.5 mm. Luckily I had some steel wire to prevent buckling.

(found that idea in Pierre Delrieu 's article) I bend it on a workmate with a hole saw clamped in.


When I fitted this on the wing it didn't look good, the tube was to thick. (see the photo on page one of the frame of the nacelle).


I tried now to make it from 4mm tube, also with a wall thickness of 0.5 mm. It appeared to be bendable without steel wire in it! No buckles!
Onother problem was the absence of frames, so I had to make some supports to solder it.



I planned to bolt the ballast lead on the steel plate



I think it's now too flimsy so it will be deformed when covered. I made 4mm tube vertical struts, but I think I will make 3 vertical struts of 2mm solid steel, which is less obstrusive.





I also made the three central wingstruts (first of 10 mm, changed that in 6 mm, that is better looking) and spent a lot of time fitting the puzzle together. This is a sketch of qall the small metal parts I still have to make.


In the meantime I turned a pulley which comes on top of the rear central wingstrut.





To be continued.

[bocorvin]

Hello everyone,

This week I made a lot of small metal parts;


and tried to make a proper support for the "wing warping servo" a very strong servo which Claude gave to me, thanks Claude! 13.6 kg... should do the yob.


It will be attached with a couple of M3 bolts to the metal plate, so which is connected almost directly to the rear wingstrut.
From 10 X 8 mm spruce I planed a more or less tear-shaped strut to connect the nose with the center wing struts.


all connected with metal plates and M 2 bolts.
Now it was time for the tailboom, made from 6.0mm with a wall thicknes of 0.5 mm. It was a bit of a puzzle to hold everything in place, but in the end the tailboom was straight and could be fitted.












It's looking allright, but to my disappointment the tailboom is to heavy . I read some stories about the vulnerabilty of the stainless steel, but this is definitely going to be too heavy. The positive thing is that I know how it all fits together, I learned quite a lot. So I ordered the tube with thinner wall (0.25mm instead of 0.5 mm) and next week I will build a new and lighter tailboom!

To be continued.

[sebastian92]

very good job
It's a pity for the weight but the arm of lever of the nose is important … of what to compensate for the weight in the back, no ?
you build very fast

[bocorvin]

Thank you Sebastian for your comment!

About the weight, I didn't estimate it correctly. The tailboom weighs about 330 grams and the horizontal and vertical stabilizers should be about the same. It would need more than 1000 gram as ballast in the nose. I think it will give a hard to fly plane . Halving the wall thickness of the tubes give about half of the weight I think. I don't like to do things over again, but I know there is no other way. I hope to get a good flying plane now

Vincent.

[GARCIA]

Félicitation pour cette construction

[Philippe26]

Hi,
Yes, it's a pity this heavy tail..... but I agree, the solution is to rebuilt it with lighter tubes... no other way .
It is boring, but now you know how to do the job.....
Courage !
Philippe

[VincentB]

Tu as fait un superbe boulot Vincent effectivement si tu as utilisé du 0.5mm c'est inutilement lourd pour un empennage, mais avec du tube de 0.25mm de paroi, c'est moins lourd qu'en bois et plus rigide/solide.

[bocorvin]

Merci Jose pour les encouragements!
Yes, Phillippe and Vincent, it was not a good idea to make the tailboom from tube with a wall thickness of 0.5 mm. It was my fear that it would buckle to easily because the tubes are very long without being interconnected (45 cm). Besides I read about the danger of the tubes getting bended. I am also not convinced it will fly easily so I liked to have it rugged enough constructed . I have another option; when the tailboom is finished I can slide a carbon tube of 5 mm inside the 6 mm stainless steel tubes ( they are open at the front and they are straight). This adds not much weight and it gives better survival changes for the tailboom with hard landings.
I don't mind making an other one, slowly I get a better idea how Fokker got along with wood, steel, wires and canvas and its good for my soldering skills!
I am waiting for the tubes with wall thickness of 0.25 mm and also for thinner tubes for the tailplanes.

Vincent

[Philippe26]

Hi Vincent,
Effectively, an inner carbon tube can be a good solution, not too heavy, and rigid enough.
Courage !
Philippe

[bocorvin]

Hi Philippe,

Glad you liked the idea. I feel a bit unsecure to use carbon tube for a retroplane glider, but when I got a buckled tailboom at Fauville, I can't repair that. In normal use the carbon tube is not functional, only with hard landings or minor crashes .

Vincent