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Sep 06, 2013, 08:01 AM
(aka Cliff Lawson)
Wright Flyer's Avatar
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Build Log

HK Sbach 342 34"/863mm - build thread - now with maiden video


This could just be down to my terrible googling and RcGroups searching skills but I seem unable to find very much about anyone who has built this plane:

https://www.hobbyking.com/hobbyking/s...arehouse_.html



I've just received the kit (which looks like remarkable value for money when you consider that all it lacks is batteries and Rx) but the included manual is "terse" in the extreme. There are some construction pictures that show, amongst other things, where to install the strengthening CF rods but some are missing the rod identity numbers and the pictures aren't clear enough or of sufficient quantity to show exactly what goes where anyway.

So has anyone else built one of these and can share advice or, better yet, is their an online build log where someone has shown the steps for construction (better than the manual)? I'm going to take photos as I go and may post something here but it'd really help if I could see how someone before me has gone about constructing this thing.

BTW searching is not helped by the fact that HobbyKing have quite a number of different Sbach 342 models (some do have extensive threads here) and not least of which is the fact that this one is 34"/863mm but there's also an almost identical 900mm one and almost everything written seems to be about that one, not this :-(

WF1903
Last edited by Wright Flyer; Sep 20, 2013 at 11:26 AM. Reason: Edit thread title again
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Sep 06, 2013, 03:29 PM
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Mike Smart's Avatar
I haven't seen it before, looks quite nice, but a tad on the heavy side for indoor use.

Mike
Sep 08, 2013, 05:22 AM
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corsair214's Avatar

sbach


http://www.valuehobby.com/airplanes/...2-epp-5mm.html i have that same one only different color from Value hobby here in the USA and the kit is only 24.00 dollars for airframe flies good well worth it
Sep 08, 2013, 07:02 AM
(aka Cliff Lawson)
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I started to build it yesterday. Pictures to come soon when I've edited them. So far I have to say this is a truly wonderful kit. It's far exceeding my expectations. The very fact that most of the EPP pieces already have CF strips or rods embedded is very nice and despite the dreadful manual (it really is dreadful!) the kit itself is "obvious". There's small holes and slots already laser cut where you need to place the supplied CF rods and strips so you can kind of work it out without the manual anyway.
Sep 10, 2013, 03:43 AM
(aka Cliff Lawson)
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Ok I'm just working out the best way to post photos so here are the kit contents laid out ready to start...



What's not shown there is the electrics pack that includes 1x9g servo, 2x5g servos, 12A ESC and the brushless outrunner.
Sep 10, 2013, 04:09 AM
(aka Cliff Lawson)
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Thisn is the kind of error in the manual that I started talking about at the top of this thread:



I've added the red text "caption missing" to highlight the fact that while there are lines drawn on the photo they have missed the text to say which number CF to use at that position.

I'm pretty sure it's "No. 15" in fact but what confused me was that No.15 is also used later in the manual for something else (the tail-skid in fact) so I figured it could not be used in two places. However there are actually three pieces of No.15 in the kit so it seems that it IS 15 to use here as well.
Sep 10, 2013, 04:11 AM
(aka Cliff Lawson)
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The following is the first step of construction - to glue the horizontal parts of the fuselage together (not sure what's happened to the "nose" in this picture! You'll see I added it in later pictures)...

Sep 10, 2013, 04:26 AM
(aka Cliff Lawson)
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The bag here contains all the numbered CF parts you use to strengthen various parts of the kit. I've extracted 15, 16 and 17 which are the pieces used to strengthen the horizontal fuse.



What's really nice about this kit is that a lot of the foam parts already come with CF strengthening embedded and you just need to add the bits that help to bond several bits together. This is the nose showing some of the pre-fitted CF that's already embedded into the foam. The diagonal parts that help to strengthen the attachment of the nose are No. 16's that I added.



And this shows some more of the parts you have to add: the fuse is in four parts, rods No.17 are embedded into a (laser) pre-cut channel down the edge of three of the parts and not only add strength but bind the parts together. Here I have put the upper No.17 into the foam already but the lower one still has to be fitted:



To fit these I just use UHU POR to run a bead along th edge of each part then squish then into the foam in the pre-cut slits using the edge of a knife blade to scrape off any excess glue that oozes out.
Sep 10, 2013, 04:42 AM
(aka Cliff Lawson)
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This one was a bit of a conundrum. These are the infamous No.15's with caption missing in the manual. While they are CF strip rather than CF rod there was no slot cut into the foam for them (in fact they cross a CF spar so it would be impossible) so I just glued them, flat onto the surface of the foam. I'm not sure if this was right or not and I begin to wonder if they had meant to withdraw these No.15 parts all together? Anyway I guess a little bit of extra stiffening can't hurt?...

Sep 10, 2013, 04:50 AM
(aka Cliff Lawson)
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The next step involves separating the upper and lower fuse halves. For once the picture in the manual was fairly clear about where to make the cut. You don't get a lot of choice really as you clearly could not cut through CF so it has to be where the vertical and horizontal pieces already embedded in the foam join at a corner:



As you can see, even with a fairly sharp knife it's quite tricky to make a clean cut through EPP. I found gentle swipes that cut a little deeper each time make a better cut than trying to press hard and cut right through in one go but the above was before I realised this! ;-)

While most of the upper and lower halves are separate there are small (4mm?) wide joiners at a couple of places that needed to be cut as seen in the middle of this image:



Another joiner to be cut near the nose:



Talking of that nose - those marks on the foam above and below the motor mounting were already there - not something I'd done. This is the only part of the foam/paint job that was a bit "sub standard". Every other part looked pristine and beautifully painted.

This was after I'd separated the two halves. Note once again all the inlaid CF that was already in position - that 's all been done in the factory - not something the builder has to worry about:

Sep 10, 2013, 04:54 AM
(aka Cliff Lawson)
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Building this kit actually takes quite a long time mainly because you need to wait for glue to dry after a number of the steps where you join bits or add CF rods/strips. So to keep myself entertained I built the wing dampers and motor mount early. These are the supplied parts to build the dampers (two sets like this):



and those then assembled:



and these are the two foam and one plywoood pieces to make the motor mount:



and, once again, those things assembled:

Sep 10, 2013, 06:05 AM
(aka Cliff Lawson)
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This is a dry fit of the lower fuse half into the horizontal patr:



It's nice that they even gave you cut pieces of foam (it's like 5mm Depron) to make "formers" that slot over the EPP and hold it perpendicular while the glue dries:



At this point:



I made my first mistake (basically because I did what the manual told me!). As directed I had glued the lower fuse half to the horizontal and now glued the upper half into place (those Depron former now make a great stand to hold the construction upright). Only later in the manual, when they show the fitting of the aileron servo do they then show the plane WITHOUT the upper half in place. This makes it easier to access the screws from above that hold the aileron servo in place and allow you to screw the control arm onto the top of it.

So if you build this kit you may want to re-order things and consider fitting the aileron servo (and wood mount) at this point BEFORE you glue the upper fuse half in place. (did I say it was a "great" manual?).

Anyway here's another view of the assembled fuse on its "stand"s:

Sep 10, 2013, 06:18 AM
(aka Cliff Lawson)
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Next comes all the CF bracing rods that give the wing and fuse parts added rigidity. The rods to use are all numbered (most in pairs for symmetrical places on either side of the plane) and while the manual pictures are poor quality and miss some of the part numbers you generally use them in numeric sequence so you can kind of work out what goes where.

What's really nice is that the places to use the rods all have pre-cut holes and slots in the EPP so you can not only see exactly where they should go but check the length to doub;e check you are using the right numbered parts - they are all cut exactly to the right lengths.

Here for example is the place in the vertical fuse where one of the rods providing support beneath the wing will fit:



The large slot there (top, middle) is for the undercarriage. To the right and below (just above the CF strip is the small hole where the wing support rod will fit). And the small angled slot just above the CF strip in this picture:



is where the other end of the rod will fit. So this picture shows that particular rod fitted. I dipped either end in UHU POR (the rods fit in to the nozzle of the glue tube) then pushed into the foam. After I then put another blob of glue on top of each join to add further strength:



This (slot):



and this (small hole):



then show where the crossing rod will attach to the wing and fuse. (in the latter picture it's the small hole to the bottom right of the angled slot).

This picture shows one side of the plane after rods No. 1, 2, 3, 4 and 5 have been fitted. No.1 is at the nose end. 2, 3 are the wing supports then 4 and 5 work back along the fuselage towards the tail end. My kit appeared to have the No.6 pair missing. While I have CF rod I can use I'm assuming that just missing one short set of rods may not matter:



(as far as I can tell this was the only thing missing from the kit). The supprting rods that help to support the tail include this:

Last edited by Wright Flyer; Sep 10, 2013 at 06:26 AM.
Sep 10, 2013, 06:42 AM
(aka Cliff Lawson)
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Everything about this kit speaks of quality. Here are the laser cut plywood parts:



and the same (easily) separated:



Now there are some mysteries here. The (semi-circular) pieces at top left are strengthening for the landing gear attachement. I get that. And the three pieces at bottom left are the sevo control arm extenders. I get that. But it took me ages to work out what the two pieces in between are for. Only later in the manual when (describing the control rods for rudder and elevator) when it said "you need to use rod supports" did I finally realise what those to pieces were for.

The three pieces at bottom right are clearly the mounts for the three servos but what are those two circles in the rectangualr piece above for? I have a sneaking suspicion they are something to do with strengthening where the undercarriage legs meet the wings but nothing in the manual expains them at all!

Talking of mysteries. The manual describes this set of foam pieces:



as "strengtheners" I think I understand that the two circles at the upper right are again involved in strengthening where the under-carriage legs attach (there's a murky picture later that appears to show them) but as far as I can see there's nothing anywhere in the manual that explains the use/position of any of these other foam parts. I thought the pieces with the semi-circular curve at one end might be to do with where the u/c legs cross the fuselage but the curve is a different radius to the plywood parts used for that so I don't think so.

Talking of u/c legs. Here they are with the supplied wheels and wheel retainers fitted:



These are really nice - I read the manuals for some other EPP foam kits before starting this build (for tips) and they showed you having to make the joint from the leg to axle by binding and glueing two CF rods. Whereas these have plywood formers for that already fitted and glued. Nice.

Just for the record here is the supplied prop - it's a GWS EP0905 for anyone who wants to order some spares (I know I will be!):



Talking of other supplied "bits and pieces". Here are the wing fences:



And these are the control rod and control horn bits:



These actually came as a revelation to me. I've been out of R/C plane flying for a few years and I'd never come across these control rod attachments with the holding screw in the side - must be something new in the last 5-6 years. It's a great idea as you can adjust the length and angle all in one go and it lets you use CF for the rods.
Last edited by Wright Flyer; Sep 11, 2013 at 04:20 AM. Reason: typos
Sep 10, 2013, 09:07 AM
(aka Cliff Lawson)
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This picture has two purposes. Once again it shows the effort they've gone to to inlay pieces of CF to make the foam rigid all over the place. You can also see both ends where a connection from fin to tail plane will be made by an added CF rod:



and this after adding that rod:



This is the plane with most of the rear/upper CF rods added:



As well as the large pieces of 5mm Depron that were used as a jig/stand to make sure the fuse sections were perpendicular these smaller pieces were also supplied but it was never really clear to me where they were supposed to be used:



This is the nose of the plane after I'd glued the motor mount (built earlier) into place:



and a closer detail of that:



This shows a dry fit of the u/c legs through the slot in the EPP and into the retaining holes in the wings but before I glued the plywood strengthening plate (and foam strengthening circles) into place:



And this is a detail once the plywood u/c strengthener was POR'd in place. Note the Z shaped slot that allows for the offset of the two legs:



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