SG-3

[ertman_176]

Hello

My name is Paweł.

I'm drawing plans SG-3, it was build in 1933. As far as I remember orginal plans was found in 2011. In polish model magazine in 2012 I found quite huge plans. I scanned them and they were laying on HDD since few days.

Details you can find here http://www.piotrp.de/SZYBOWCE/psg3.htm











I drawing glider in 1:1 scale, just outlines because as far as I know drawing and building models it would be much easier to scale few models. Here you can see first lines.



Plan as a model making plan is quite good, but with scale 1:1 there is a few scale mistakes that i would try to remake.

Another thing about it it is that there is need do change profiles of wings. And here is my ask for you friends.

I post here closeup of profile that you can read better.




Original is shown and my bet profile HQ 3.5 18%. All is shown in 1:1 scale but first model i plan to build 1:3 scale with straight wings, also glider don't have breaks with 5,66m wings

I hope that you will help me to choose right profile for my model.

Pawel

[Eric Spore]

Nice sailplane. It seems to be strongly inspirated by the "WIEN" from Lippisch like many other sailplanes designed and build around 1933 (that's the case of my hungarisch Karakan).

For the wing profile, I would recomment the MS 535 family from Matthieu Scherrer. This family of profiles is an improved version of the famous Gö 549.
MS535 coordinates can be found here: http://tracfoil.free.fr/airfoils/m.htm
Thicknesses of MS 535 profiles varies from 12 to 16%. Camber is similar to Gö profiles. It means slow flying and low sink rate. Obviously glide ratio is not the best, but this is not the target with vintage gliders.

I wish you a successfull construction.

[VincentB]

Hi Pawel, welcome on the forum

[milo]

Cześć Paweł.
Nie wiem czy zauważyłeś, ale na RP są twoi rodacy Może czasami coś napiszesz po polsku.
Świetny szybowiec, będzie na pewno super model, bacznie obserwuję

[ertman_176]

[OT ON] Milo ale ja doskonale o tym wiem Jak tam lotnisko w Elblągu, jak się ma p. Roman? [OT OFF]

Ok, just download MS535, I will try add it tommorow on plans. I work in other place than i have internet network. It is SO MUCH easier if you don't have internet at work.

Someone any other ideas about profile ?

[ertman_176]

DAY 2

As you said i checked MS profiles, MS retro is not proper for SG3 wing.

First thing before, SG3 wing that i'm building has 0 dihedral, leading edge is back but it is straight. Ailerons are from ~middle to the end of wing. First 4 ribs are same. In original ribs are calculated from 2 profiles between begining and middle, and next part from middle to tip.

What did i do today ?

I checked idea of MS535 with all 3 types. Tip with MS535 3v is to thin for me, less than 15mm ex. tip ending.

I checked Ms 535 1 as main and MS535 2 as rest. Thicknes is ok for me, i have about 20mm at last rib.

And my bad [i didn't draw so long ...] I didn't manage that change between 1 and 2 will be so drastic. I saw it just after end of today work.

To admonish you here are pics:





Just to motivate myself and you to discussion i show next renders









Model will have 5,66m wing span with main rib 466.66mm, fuselage 2350mm.

[ertman_176]

DAY3

I made new wing, looks quite well for me. Now i need to draw all ribs and alierons.





As i said i used MS535 1 as root and MS535 2 as tip. Ribs are 70mm tall at center and 19mm tall at tip. There is still no ending.

In this place i must consider ply cover for wings, but it is quite expensive. I have got lot of 20x3mm 2500mm long linden wood. I can cover wing with it [i will use planer to make it 1,5-2mm thick] and add 0,6mm veneer plates to make it look like ply. Also i plan same cover for fuselage.


Between drawing wing i made aileron lever, Orginal has 3x3mm metal plates [don't remember aluminium or steel]









I'm not sure about 1mm rivets so i think about using welder to join 3 pcs 1mm of steel, and then make actual 1mm rivets.

PS. My 2500mm long benches [yes i have a few] will be to short so i need to plan some kind of extension.

[ertman_176]

Day 4

Not much for today/tonight ? Just came back from my workshop. I had to clean up so much mess that i made.

I made drawings of front skid [and recalculete it to 1:3 because i need to find quite big piece of ash - 77x3,3cm 3,3mm thin 2pcs].





Also i made drawings of absorber and scale it, make cnc file to cut rubber. I think about using few layers old bicycle inner tube and glue them with kind of "shoe" glue.





Also made some trying with fuselage, just to think about construction line for bench.

For 11.12.2014 it will be all

[ertman_176]

Day 5

After night i made only hinge

[ertman_176]

Day 6

Today i made rudder lever





Next i started with drawing fuselage





Drawing is 1:24 original and scaled to 1:1. I have got 1:1 dimension and as you can see it is not as well as it should be





If you can see i have about 30mm to small drawing. If plan got 1mm displacment in 1:24 we get 24mm in 1:1. A lot

I made only two simpliest parts

[ertman_176]

Day 7

I don't work at sunday

So monday i started 7 day of drawing/building

I made next 3 formers





I had to draw wing ferrule because former #6 and #7 use them. Bad thing about it is that drawings of them are poor dimension





Just made a sketch and scale them

Front





Main





Also i made new T-squere for my table saw and take few cuts of coverage wood. Just relized that it is 3mm thick and 2800mm long so i'm very happy about that because it will cover almost all wing. I think hard about how to build wing tip. Will try to explain tommorow what i'm affraid about

[ultralajt]

What you was affraid about? Can I help?