Jilles Smits 1/3 scale SG38

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Peter Balcombe
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Re: Jilles Smits 1/3 scale SG38

Post by Peter Balcombe » 30 Oct 2018, 10:35

Fuselage lower box structure now assembled to the state shown on the plan for the initial assembly.
The release servo position is up front & the rudder servo just behind. The elevator servo will be mounted in the seat base. All servos will be hidden by the fuselage side plates/seat base in due course.

Next step is to start constructing the 'A' frame parts.
Attachments
Lower Box Right.jpg
Fuselage box from RHS
Lower Box Left.jpg
Fuselage box from LHS
Lower Box_FrontLeft.jpg
Forward part

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Peter Balcombe
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Re: Jilles Smits 1/3 scale SG38

Post by Peter Balcombe » 03 Nov 2018, 11:08

Mast assembly construction has progressed to the point where I can check how the rear fuselage fits.
A slight hiatus on the forward part of the mast whilst we sort out a couple of missing tabs slots to enable the wing assembly to interlock correctly.
(CAD doesn't always produce what is expected!)

Its probably worth noting that there are an awful lot of wooden pieces which need to be assembled to make up the overall fuselage, so a builder needs to be very careful to make sure he carefully notes all of the drawing notes and supplied cross-sections to make sure the various items are assembled in the right order and place.
Jilles has done a very good job in providing a detailed plan which appears to mimic the full size construction and finished appearance.
Attachments
Initial_Mast_Rear.jpg
Initial mast Assy + Rear fuselage

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Peter Balcombe
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Re: Jilles Smits 1/3 scale SG38

Post by Peter Balcombe » 04 Nov 2018, 18:11

With missing slots (cutting files to be amended) added, the central wing structure can be added to the pylon/mast structure.
The first bits are the F7 pieces either side of the rear upright, notching into the forward mast.

The forward mast lower side pieces are also fitted to the structure prior to adding the lower part doublers and closing up the mast box assembly (to be done tomorrow).
Attachments
F7 added.jpg
F7 added to mast structure
S1 added.jpg
Mast lower sides added

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Cliff Evans
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Re: Jilles Smits 1/3 scale SG38

Post by Cliff Evans » 04 Nov 2018, 18:19

Peter, can take a picture with something we can relate to to get the size of the model.

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Peter Balcombe
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Re: Jilles Smits 1/3 scale SG38

Post by Peter Balcombe » 05 Nov 2018, 12:45

Here you go then.
I have completed the forward mast assembly and added the wing root ribs.
That is a 1m rule for scale.
Although trying to be careful about getting assembly order correct to avoid locking parts out, I failed to put in 2 balsa pieces just above the wing root ribs whilst assembling the F7 ribs just inside each root rib :o
However, these are only to provide a glue support land for the mast top covering in due course, so was able to cut these where they rest on the crosswise former at the wing incidence pin location and insert later as two separate pieces.
It looks like I need to do a lot more work on the forward fuselage before I can put the side skins on in order to avoid more lock-outs! This will need me to start making some of the many brass brackets ;)

Tow release and rudder servos screwed into place the check fits, plus servo plate added for the elevator servo (this will be hidden under the seat assembly).
Attachments
Overll fuselage mockup_small.jpg
Overall fuselage mockup

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VinceC
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Re: Jilles Smits 1/3 scale SG38

Post by VinceC » 05 Nov 2018, 13:25

Thanks Pete, just over 12 inches long then

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Peter Balcombe
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Re: Jilles Smits 1/3 scale SG38

Post by Peter Balcombe » 05 Nov 2018, 15:30

Vince,
Er, not quite ....
More like 2.092m overall length, 3.45m span and 810mm overall height ;)

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Peter Balcombe
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Re: Jilles Smits 1/3 scale SG38

Post by Peter Balcombe » 05 Nov 2018, 20:26

I forgot to say earlier in this thread that although the Bill of Materials (BoM) lists the various labelled parts (NC cut & stripwood), I thoroughly recommend going though the BoM against the parts and drawings before you start any of the build.
The reasons for this are to (a) check off your laser cut kit parts, (b) identify where each item fits on the plans & (c) identify the stripwood required to be ordered, (d) split the NC parts into various build groups (e.g. fuselage, wings, tailplane, rudder).

I also noted the purpose of each part on my BoM to help later on.
In doing this, I identified a few items that had been accidentally missed off the NC cutting files and a couple of wrong quantities (drawings since amended), but also identified a couple of items which didn't appear to be mentioned anywhere on the various drawings.

Items which fell into this latter category are GUS1, V13 & V14.
Jilles has provided lots of additional information on the various cross sections provided, but the above parts don't appear to get a mention on any of them. So...
GUS1 is a small slotted gusset which is used when glueing the elevator servo tray ST2 to the top of the forward fuselage deck DKD. It will be apparent from the tab/slot which way around it goes on the front of ST2. A photo below shows GUS1 in place.

The V13/V14 items fit at the very lower rear of the rear fuselage (tail skid area).
A problem I find with CAD drawings is that there are so many lines on them that it is sometimes difficult to decide where some parts end, unless you have an infinite number of notes/sections to show what is going on.
This was the case when I was assembling the fin post, as although there is a drawing note on the skid area saying that CS3 (carbon strip) & V5 go to the bottom of the skid, it didn't mention the V6 strips each side of the CS3/V5/CS3 sandwich and also didn't mention the NC cut V13/or V14 pieces.
Once you realise that V13/V14 actually fit into this area, all becomes clear .... albeit somewhat belatedly for me ;)
The V6 parts stop at the lower level of the bottom rail (V2,V4,CS2). The V13 piece fits on the bottom of the V2,V4,CS2 rail, forward of the V5/CS3 sandwich, with the V14 pieces acting as doublers & going each side of the lowest part of the V5/CS3 strip.
I mistakenly took my V6 strips to the bottom of the skid and have had to cut the rear off each V14 piece to get them to fit in the remaining space.
Note that this area is further doubled by the two outer V15 parts, so I don't think it will be a problem.
The photos below show V13 & the 2off V14 parts (one of which has been shortened), the underside of the skid area, both before & after fitting the V13/14 parts.
Attachments
GUS1 location.jpg
GUS1 location
Rear_skid side.jpg
Rear skid underside
Rear Skid empty.jpg
Rear skid void
Rear_skid filled.jpg
Rear skid filled

Jilles
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Re: Jilles Smits 1/3 scale SG38

Post by Jilles » 06 Nov 2018, 02:13

How many notes are required on a drawing. coming from a engineering back ground I would say probably never enough.
Even though this SG38 fuselage looks a simple frame from sticks and ply plate, the time spend on working out and detailing took approximate twice the time then for a standard fuse of previous vintage designs. On a scale like this lots of features has to be added to make it look scale, the final finish has to be kept in mind, ready available material and it has to be structural sound. If you create a drawing of your own design one takes some items for granted because they are already in your mind. That is why in an professional situation an other person(s) will check the drawings.
In this case Peter as a first builder is that check person. All findings and recommendations will be amended on the drawings as soon as the built is complete. so far Peter is doing a great job.
As I mentioned before on various occasions my designs are not for the beginner and some details are left to builders preferences.
Above is not an excuse for problems on the drawings but it shows how things work. Compared to 10-15 years ago we are spoilt with CAD drawings, NC cutting and modern composite materials, but that does not mean everything will be perfect. Remember the hand drawn more often than not inaccurate drawings, you had to cut everything yourself and make it fit, maybe we are loosing skills here in the process.

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Cliff Evans
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Re: Jilles Smits 1/3 scale SG38

Post by Cliff Evans » 06 Nov 2018, 07:50

I have to say that Jilles does supply an awful lot of info with and on his plans that you just do not get with many others! Mr Williams is another good example of someone that supplies copious amounts of build info either in his build threads or available from him on cd.

This is where this forum comes into its own. We have a wealth of knowledge on most aspects of this hobby available to all here, from seasoned modeller to the real novice which does allow the novice to have a go at something they would normally shy away from. There is always help and advice available from members and for that I commend you all. The ARTF models that have flooded the market have over the years killed off quite a lot of the need to build but, I feel that things are changing in that people are definitely coming back to building which, in turn encourages the likes of Jilles and Chris to keep producing plans for us to build from.

Also, I would say to the new members that would like to perhaps have a go at designing themselves, talk to Chris and Jilles and the many others here that have designed their own models, I am sure they would offer advice to the would-be designer to help them in their quest.

I must end on a big thank you to Jilles and Chris for continuing to produce designs for us to build from.

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