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SG38 1/4 Scale (Krick)

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Cliff Evans
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Joined: 29 Dec 2019, 15:13
Location: Bristol
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Re: SG38 1/4 Scale (Krick)

Post by Cliff Evans »

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

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mjcp
Posts: 111
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Location: A wind swept hill with no wind, in driving distance of Windsor, UK
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Re: SG38 1/4 Scale (Krick)

Post by mjcp »

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
m̶j̶c̶p̶ Marc

Hanger -
Graupner (old) K-8b, Mini Solius chuck glider conversion, UMX ASK-21, HF/Czech 2m ASW27, DG808s 4m, X-models Mini-blade, Lidl glider pitcheron.

Ted
Posts: 38
Joined: 28 Oct 2019, 15:08
Location: South Wales

Re: SG38 1/4 Scale (Krick)

Post by Ted »

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.
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Ted
Posts: 38
Joined: 28 Oct 2019, 15:08
Location: South Wales

Re: SG38 1/4 Scale (Krick)

Post by Ted »

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 :shock: 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 :evil: , 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 :roll: 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 :cry:

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 :)
Attachments
SG38 - My build April 2020 (183).JPG
SG38 - My build April 2020 (200).JPG
SG38 - My build April 2020 (199).jpg
SG38 - My build April 2020 (179).jpg

Ted
Posts: 38
Joined: 28 Oct 2019, 15:08
Location: South Wales

Re: SG38 1/4 Scale (Krick)

Post by Ted »

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.
Attachments
SG38 - My build May 2020 (248).jpg
SG38 - My build May 2020 (286).jpg
SG38 - My build May 2020 (273).jpg
SG38 - My build May 2020 (260).jpg
SG38 - My build May 2020 (258).jpg
SG38 - My build May 2020 (257).jpg
SG38 - My build May 2020 (249).jpg

Ted
Posts: 38
Joined: 28 Oct 2019, 15:08
Location: South Wales

Re: SG38 1/4 Scale (Krick)

Post by Ted »

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 lase 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.
Attachments
SG38 - My build May 2020 (297).JPG

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Cliff Evans
Posts: 321
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Location: Bristol
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Re: SG38 1/4 Scale (Krick)

Post by Cliff Evans »

Nice job.
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Ted
Posts: 38
Joined: 28 Oct 2019, 15:08
Location: South Wales

Re: SG38 1/4 Scale (Krick)

Post by Ted »

Thanks Cliff

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

[youtube][/youtube]

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