Scale Soaring UK

OK so I finally found my way back to the building board to build my long awaited 1/4 scale SG38 which I purchased several years ago.

All of the instructions for the kit are in German, fortunately when I purchased the kit a few years agao I had the foresight to source a translated version.
So if anyone else is thinking of building one of these you'll more than likely need these translated instructions which can be found here:

Hope this helps.

OK so lets start with the fuselage:

Some of the hardware:

Fuselage and "A" frame assembly:

Wing centre section:

This is Tony:

LOL Yes I don't hang about, should be done by lunch time

Skid Lamination & Shock Absorbers:

make up lamination spacers and angle pads for Ply, trace out from plan, make template, soak in hot water, glue bend slowly while attaching clamps, leave to dry:

Main wing fixings:

Tail Frame:

Just thinking ahead for covering material, I see you cant get Solartex anymore, can anyone recommend an alternative product?
EDIT: just found some, OK so its going to be either white or natural, is there a difference, its hard to tell from the colour chart on line.

Cliff Evans wrote: ↑29 Oct 2019, 11:25 This is quicker than Mr Williams builds!!

Truth is I'm currently working on the tail feathers and there appears to be a couple of pieces of balsa missing so it will slow up somewhat until I can source some replacement, no RC shops near me so will have to order online , I did like to take a trip out to the RC shop have a look at all the stuff I couldn't afford and carefully hand pick balsa sticks n sheets for best quality, oh well how times change.

Tony needs a seat:

Pilot seat and Harness:

The ply seat took a long time to cut out of the 1.5mm ply the shape is barely marked on the plywood face, considering that all the other ply parts have been easily pressed out, I can only assume that there is an issue with the press which is not good considering the cost of the kit, not happy



OK finally finished whittling wood and now have a pilot seat for Tony just need to make a harness to keep him on it.

Rudder controls:

Ballast weights:

Rudder:

Stab and Elevator:

Laminating the centre section of plywood and core balsa


Getting there

OK so I've found a Model shop in Cardiff that sells Balsa "Hoora" will drop by over the weekend, pick up a few pieces to complete the tail-plane.

In the meantime, got on with finishing the rudder and covering a few bits, going for natural Solortex.

Hi Ted, looking good - I have one of these bought years ago but I didn't realise that you can build one in a week ! You really work quickly !!!!!!!
Can I ask what you used to stain the wood and if you had any problems with that ?
Also, have you found any problems with the parts (except the seat) and the build instructions ?

Looking forward to a flight test report too.

Paul

Paul_Williams wrote: ↑01 Nov 2019, 21:38 Hi Ted, looking good - I have one of these bought years ago but I didn't realise that you can build one in a week ! You really work quickly !!!!!!!
Can I ask what you used to stain the wood and if you had any problems with that ?
Also, have you found any problems with the parts (except the seat) and the build instructions ?

Looking forward to a fligh6 ttest report too.

Paul

OK so the stain used is a repair stain purchased from my local Wilko store for £2.75 available in 2 shades Dark and Light oak, it I'm using the lighter shade for all areas although I may use the dark for the main wing panel sections for contrast.
The stain does have wax in so you will need to balsalock the areas that will be covered otherwise the covering will not adhere.


Instructions: The translated instruction I have posted are OK but make sure to read them thoroughly as the comprehension is difficult and constantly referencing the parts list both on the translation list and the German instruction list on the last 2 pages.

Quick Build: Well I did the initial build over 2 weeks of evenings before I started this post and after inadvertently using the wrong piece of balsa for gussets I have had to stop the build until I can purchase some more balsa, hopefully later today, the aim is to complete the tail section by the end of next week although the wife has a list of DIY to do around the house , Ideally I will complete the tail section and covering before I make a start on both main wings.

The seat: you'll find the plywood seat is only marked on the plywood not actually punched through so a lot of cut to near size with fret saw and sand in the rest, the hole were drilled out and again final sanding to shape, just take your time, its worth it to get the finish.

Hope this helps

OK so after a long and tedious winter I’ve found the time to revisit my SG38 build not COVID related just made the effort to hopefully see it to its finish.
So lifted the tail section off the building board and got out the belt sander, be careful if you have one of these they can be a bit fierce and before you know it you’ll have ruined what you spent hours on.
Having profiled the stabiliser tips, test installed to the tail boom, looks good, need to finish those gussets on the top side, shouldn’t be an issue, profiled and shaped the elevators ready for stain, hinges, control horns and covering, Note they are still joined as this is how I build them on the board, will separated them after installing hinges and dry fit and checking against the stabiliser for good fit.

OK so covered the elevators and test fit hinges before permanently epoxying hinges in place to the elevators only this makes certain that the hinges will fit to the tail-plane section later, also installed the control horns using 5 minute epoxy resin.
Next job to finish the tail stabiliser, more gusset cutting

OK so finally finished cutting gussets, stained, left to dry overnight, balsaloc and covered, installed elevators and fitted to tail boom, happy with the results.

What's next, oh yeh need a couple of main wings

OK so started the main wings, well the left one.

Followed instructions, takes ages to figure out what goes where, luckily I spent some time before starting the build to check off all the parts against the contents of the box, you must do this otherwise you will get confused/lost
Look at the plywood and balsa layouts at the back of the plans, get yourself a pencil and a magnifying glass and check off all the pressed parts, write the numbers on the parts , there should be 2 of everything.

Then lay out all the bundles of balsa do not disband them as they are bundled logically i.e. ailerons , main spruce spares etc.
I made an error and used one of the block lengths of balsa which was meant for the rudder leading edge so had to remake it from stock

TIP: the main ribs are laid out on the plan upside down and have to be soaked in something, yes something what is recommend is glow fuel to allow the drawing to be transparent to the other side of the paper and them flipped over to build the ride(Starboard wing, well actually its the port wing when looking form the rear, although I think I'll use something else other than glow fuel, you would have thought that considering the amount of money the kit costs I think it was in excess of £250 and that was several years ago that you'd get both wing plans .

Where was I, Oh yeh so the main spar webbing is a sheet of 3mm x
35mm x 79mm and this is the set distance between all ribs!!! so when setting out the ribs simply use a scrap piece of balsa 79mm for referencing the distance between each rib so when you get to installing the main spar webbing the distance is set accurately so no need to trim, yes I did have to slightly sand some of the web edges to ease the fit but nothing drastic, I will use this technique when I build the other (Right / Starboard) wing.

Well that my rant over with, I have made slow but good progress with the first wing which is what I'd expect although having prepared both main wing spars and identifying cutting out all the parts for the starboard wing it should build itself

Production fault: All wing ribs 145 which is the shorter main wing outer section forwards of the ailerons all have double spar cut out sections which is incorrect as the main spar is only 1 x single spruce section as apposed the the main root spars which does have a double laminated spruce spare, I have highlighted this in the photos and have had to add a scrap of balsa to compensate the the deeper sit in the balsa rib. (Hope that makes sense).

OK so the first wing is progressing slowly, decided to use 3mm gussets on the wing tips as apposed to 1.5mm as per instructions makes it easier to work with and looks better IMO weight gain is negligible as its not a high performance model.

Installed rudder closed loop.

OK so made up the wing spar templates, they were not pre cut so had to cut them out by hand
Installed all rear control lines, had to add a lower torsion line tot he sailplane as it was not quite level but I did expect some slight warping over time as I had anticipated so this was going to be installed at some point just to keep things tort as the tail-plane does flex quite a lot.

Test fitted the wing, couldn't resist this now the wing was off the building board, looks good, NOT glued the main spar box section yet until the other wing has been built and test fitted and aligned correctly.

NOTED: Not a lot of rudder movement even with the max servo arms installed, may have to address this after first maiden flight if not responsive enough, elevator looks ok but then again I'm not going to be throwing this model about in the sky.

Covering main wings, realised that Solartex no longer available so maybe substitute with Oracover , told its the same stuff, would appreciate if someone out there could confirm this as I can't get a sample anywhere, looking for natural, unless someone has 4 metres of solotex for sale

You will need to get that rudder movement sorted before flying. If mine is anything to go by, It will need a fair bit!

Hi Cliff

Thank you for your reply and advise.

Yes I thought as much ideally the rudder horn would be located nearer to the vertical hinged pivot point which would provide more deflection.

May I ask how yo resolved your issue, i don't want to cut the fuselage about if there's another solution.

Cheers

Mine is 1/3 scale and has a lot more room so it wasn't really an issue!

You're already (effectively) using pulleys in 1:1 mode in the cable run, could you fit a 1:3 pulley arrangement in that box section?


Servo pulls the smaller, existing cable is attached to the larger attached on top?

Let me know if you need a pic as my description might not render as a visualization in your mind!

M

Thanks both for the advise.

I have have compared the plan to what I have actually build and noticed an offset with the rudder horn centre point, the plan denotes that the horn cable attachment point is aligned with the centre pivot point. and mine are only slightly forward of this which may be why I only have minimum deflection.

Did some research and ended up reading all about geometry and closed loop isues, crossing lines etc. https://www.modelflying.co.uk/forums/po ... =98938&p=2

Don't think there's enough room in the fuse to install pulley ratio, possibly look at increasing the servo arm and trip the fuse side to accommodate, may also cross the cables to ensure there is no binding on the servo bearing.

OK so its been a while however I have made progress having built one of the ailerons although the fist wing is build upside down the aileron that is on the same side of the plan is for the right wing, oh well I'm sure it'll fit when I finally get to build the other wing.

So not impressed about having to soak the plan in fuel oil or similar to get the other wing build, sure;y for the cost of this kit there would be a full set of plans and laid out correctly i.e. to make a full wing plan you have to join 2 sheets together I'm beginning to think I should have gone for the 1/3 scale version (short kit) with all the parts lazer cut, yes I would had to buy additional balsa etc but at least the ribs would be uniform and already cut out, some of the parts especially the seat plywood have been a pain to cut out , well that's my rant over with, I'm working on the right wing now with the main spars and ribs all assembled, oh dear, appear to have run out of webbing balsa will have to order some with the covering and while I'm waiting for delivery I can build the other aileron and fit all the gussets, how I loath cutting gussets

Oh well if all goes well I should be applying the covering in a few weeks and then sort out the rudder movement, I think I'll add another servo to the fuse bay and mount both rudder servos sideways with an extended horn to provide more movement and either mix on the radio or use Y lead, yes slightly more weight gain but happy to do so as this is not a floater and will be for slope souring.

Note the servo extension cable installed for the aileron and is bonded in with either silicon or in this case "stick like" I have used this technique many times before and have never had any issues, these are 2 older servos so I cut off the fixing lugs so the back of the servo sits tight against the webbing, "Tip" test servos before installing test servos on the work bench lay them next to each other facing the direction that they will be when installed into the wings checking that the arms are centre and movements are opposite to each other ans label them accordingly, this will avoid any issues later when you connect everything up

OK so finally finished both wings and have stained and Balsa loc'd set temp installed Aileron hinges to ensure alignment.

just started to cover first wing with Oratex, yep I'd swear its Solartex currently awaiting delivery of 2 more rolls so I can get on and finish.

Well I've finally finished it, Happy with the results as always maybe do some things different if I was to build again, lets see, use a stain without wax, this wasn't really an issue as I allowed to dry well and then Balsaloc'd everything but it produced the colouring I wanted.

Good bits:
Oratx covering is perfect for this type of semi scale model for ease of application, colour choice 3 x Oratex 2m Natural Clear I think the product code was (000) used 3 roles with an overlap joint on the underside of one wing at a rib section, if your careful of how you measure and cut the 3 separate lengths for the rest of the wings you should have just enough to cover the bottom of the last wing with an overlap joint at a rib, I think I did mine at 1 rib inboard from the aileron.

Flying wires was more than enough so if you make a mistake there would be enough to redo maybe 2 lines.

Bad bits:
Not enough 2mm nuts n bolts and the correct length to complete the model so had to purchase more, oh and brass plate was insufficient.

Having to cut out the plywood parts was a right pain.

I think there may also be an error on the plan for the ailerons as the control horn does not align fully with the exit slot for the control rod. it looks like when the plan is in its first position to build the first wing and aileron the plan would alignment would be correct for the other wing (right) aileron.

IMO (In my opinion) and its only IMO that considering the cost of this kit why it does not have laser cut ribs although assuming the kit had been designed before laser cutting became commercial viable I can understand this, however if this kit was to be upgraded with laser cut ribs it would not only make the build quicker but more enjoyable and with a better finish IMO.

I I was going to build this again I would go for the 1/3 scale short kit, this build was started back before the winter and Covid, now completed and ready for test flights, I'm sure I'll get some great flights out of what I'm expecting to be a "Sky Slug" performance but that's what I expected from the outset, I will try and get some photos of Tony (that's the pilot) taking the SG38 for a pleasurable saunter day out.

Thanks to Scale souring UK for letting my post my build and I hope this goes some way to keeping the builders old and new inspired.

Nice job.

Thanks Cliff

Here's a video of the 1st test flight, also make several others so ready to take on some real souring.

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