Sbach 342, profile quick build 36" plans - RC Groups
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Aug 20, 2013, 08:18 PM
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limmacslim's Avatar
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Sbach 342, profile quick build 36" plans


This is my profile Sbach 342. I searched & found a few different sbach's knocking around here but thought I would share my plans incase anyone is looking for a simple park sized profile version that flies on a blue wonder sized motor.
Im a bit of a noobie with the 3d stuff but it does fly good . Its stable, floaty & makes a nice 3d trainer, very easy to prop hang, harrier & jack knife but has its own small quirks. In general its pretty easy going & I think for a learner would be easy to fly in a sporty fashion, a heavier & quicker sport setup would probably also work well.

Its made with 6mm depron, 92cm / 36" wingspan, 79cm / 31" length. AUW should be around 250g (around 5.9 oz/ft² WL, 4.8oz/ft² CWL), my one came out at 260g.
My current setup is a rewound 1300kv blue wonder motor, 9x3.8 prop, 12a HW esc, 3x 9g servos, 450mah 3s lipo, 4ch frsky rx.

The wing is marked at 30% of the MAC which makes a decent (slightly nose heavy) starting point for the CG, I found it needed to be roughly 10mm rearward for level flight both inverted & normal way up.
I have a 6mm hollow carbon rod for the wing spar & too much hot glue, the motor area is setup for a blue wonder & may need enlarging for a motor with a wider base. I used zero thrust angles. The wing fence shape was "borrowed" from another Sbach design.

This is a hastily chopped together video of me tooling around at the park with an older airframe which needed more authority on the elevator & ailerons.
Sbach 342 92cm depron RC model (4 min 10 sec)


A more recent unedited video of the current setup.
Sbach 342 depron RC model (4 min 46 sec)
Last edited by limmacslim; Aug 22, 2013 at 09:39 PM.
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Apr 11, 2014, 09:34 AM
Retired CAD guy
birdofplay's Avatar
Well I just liked this design a bunch and I also loved the way limmacslim flew it in the
vids provided above.
Most vids don't really "wring out" and new design and show it's true capabilities.

regardless, I asked limmacslim if I could CNC cut this design and then promptly
SCALED IT UP to ~ 50" span.
My neighbor has an ADDICTION X and wanted something about that size
to get comfortable with before getting serious with his Addiction.

Using 2 FULL sheets 9mm Depron , some serious 6mm sq CF for a VERY STIFF Spar
and a Motor Mount borrowed from the "Hammer" , we came up with the plane in the Pic


Final LG , Specs and Equipment will follow soon but it flys well in strong wind
fills the bill for my neighbors Addiction X " trainer" and then some.

I will make this available as a CNC cut Kit with ply horns and CF spar.
Gerry is lobbying me to invest in and offer a Full Kit on this one.
So after we get the LG and optimum Motor and Prop size nailed down
I may offer the total package as an option,

Comments?

Bob
Hoosier Cutout Service
Apr 11, 2014, 12:49 PM
All can fly...Launch stronger!
ttersu's Avatar
Great new Bob!
Apr 11, 2014, 12:58 PM
Retired CAD guy
birdofplay's Avatar
Thanx ttersu.

In the next hour or so I plan to go out and get some Vids of this new Larger Version.

Bob
Apr 11, 2014, 04:19 PM
Registered User
limmacslim's Avatar
Hey Bob, nice work . Looking forward to seeing it fly!

Im also currently building another one for an indoor meeting in a sports hall. Not sure how large the venue is so it will be a smaller version with 3mm depron, maybe 27" span & aiming for lower wing loading than the last one. Im trying to get it to work with a low kv 11g 1811 turnigy motor.

I will try to get some video up if its built & working in time for the meet on monday.
Apr 11, 2014, 04:46 PM
Retired CAD guy
birdofplay's Avatar
Thanks,

We are waiting for the 4mph winds predicted to calm down below 10 mph !

Bu there's a couple more pix while you are waiting for vids.

BTW Based on Gerry's Prototype build, I've revisited the CAD file and added a routed channel for the spare to go in plus cutouts for all servos
as well as aileron cut out holes for alignment.

Best

Bob
Hoosier Cutout Service
Apr 11, 2014, 10:22 PM
Retired CAD guy
birdofplay's Avatar
Went out just b4 sunset and got vid on my Galaxy note
Plus some more om my old Lumix camera
Trouble is I havent used the win vid editor much
So it'll take me awhile to get it all together.

I really liked using the Note pad as it was easy to keep
The plane in the frame.

L8r
Bob
Apr 12, 2014, 03:03 AM
Registered User
closeflyby's Avatar
Great Job!

It looks like it flies really nice. I think I'm gonna have to build one when I have the time! The sbach is one of my favorites. Do you have any problems with the motor getting too hot? Isn't the 9" prop with 3s a little to much for the blue wonder?
Apr 12, 2014, 09:14 AM
Registered User
limmacslim's Avatar
closeflyby, I have been running my motor with a 9x4.8 for something like 10 months with no issues although the motor is rewound with thicker wire & stays cool at 10a-11a. Its actually the 450mah 25c lipo's that don't like it . An 8x4 prop also works well.

There's probably not a definitive answer because the blue wonders do come in a few variations but im pretty sure I have heard of others running 9" props on a stock motor, I have a 16 magnet WYE version which was bought from here
I also use these gws "clone" props because they are pretty efficient compared to similar props & draw less current.

This is the current state of my "used & abused" motor, the copper still looks like new & in very good condition.
Apr 12, 2014, 09:27 AM
Retired CAD guy
birdofplay's Avatar
Nice looking Wind.
Even , Clean & Tight !

I used to wind my own too.
Another fun and informative part of this hobby.

still working on vid 9 I had to sleep )
Maybe yet today.

Bob
Apr 12, 2014, 09:52 AM
Registered User
limmacslim's Avatar
Thanks Bob. All in good time with the vid, sleep in pretty important stuff

I agree, its a very satisfying & often helpful thing to do.
Last night I tried to get a 1811 motor running on 2s with an 8x4 but it did not behave well with the larger props. I moved onto a 11g m2020 motor which is known for having bad stock windings & being very inefficient, It now has a reasonably tight low-kv wind on it & am hoping for better performance. Fingers crossed.
Apr 12, 2014, 11:05 AM
Retired CAD guy
birdofplay's Avatar
Ok here it is !

I just did a quick clip and sound track.
I just used WinLiveVideo maker on WIn7 laptop.
Nothing Hollywood about this one,
except Gerry's Nice paint job.

Sbach50 (3 min 38 sec)


Best

Bob
Last edited by birdofplay; Apr 12, 2014 at 11:38 AM.
Apr 12, 2014, 11:48 AM
Registered User
limmacslim's Avatar
Awesome job & Nice flying!

Your larger version looks very light & floaty, wing loading seems excellent, it looks even more forgiving than the smaller version.

Also looks like a lovely day for flying over there .
Apr 12, 2014, 02:38 PM
Retired CAD guy
birdofplay's Avatar
Thanx, but ...
My vid was CUT while yours were continuous and Close in.

We're learning, however :-)

yup yup yup :-)
Spring is coming ! 75 F today but 20+ Mph winds in attendance :-(

YES the weight before some LG additions was only 18 OZ .

I'm thinking that a Beefy LG like the Hammer has and a bit larger motor
shouldn't affect that floatyness too adversely.

Gerry has ordered a $30 motor from Wicked and I have some alternatives to try
before spending another $30 and yet another motor.

Given the span, I am going to try a 3010B-1300kv 400w motor that I already have in house.
Will use a 40A ESC Plush and check the watts with various props B4 venturing out.
Probably Prop it to get far less that 400w and keep the amp draw under 40 ( obviously ) .

I have "MY" fuse assembled and the wings center glued with ailerons cut off.
The spar goes in next. While that dries I'll be tapering the Surfaces .
I really DO NOT see the need for a Build Thread as this is SO straight forward.
And it's for intermediate to Expert fliers anyway. I mean 3D, of course.

I have 4ea CS-239HV MG servos in the drawer.
So even tho they are for Thin Wing use I'm going to slap them in the Sbach anyway.

Gerry and I both "want" to get 2 of these in the air at the same time SOON !

It wasn't too many months ago that I'd though about a fairly calm spring time with a few
new prop in slot, slide on ground, Jets test but then Gerry came along and dragged me
into OUTDOOR 3D .
Now I have the HAMMER and This Sbach and an old Piaget for calm days.

Hmmm I wonder how the Piaget would do SCALED UP ? wheeee :-)

Bob

Hoosier Cutout Service
Apr 12, 2014, 03:20 PM
Registered User
corsair214's Avatar

sbach


yes and even more windy tomorrow


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