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Old May 31, 2013, 05:18 PM
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Scratchbuilt Aircraft Plywood frame

Hi,

I working on scratchbuilt frame. I will use birch plywood specially made for airplane and lasercutting.

The frame size is 600x600mm and i can't choose between 3mm or 4mm plywood. Any advice welcome....



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Last edited by sixbras; Jun 14, 2013 at 09:32 AM. Reason: change to build log
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Old Jun 01, 2013, 11:03 AM
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This is probably not what you want to hear, but I learned a valuable lesson today. I let my son have a go of my (wood framed) quad. It went from approximately 100ft altitude to zero before I could wrestle the controls off him. Luckily the hard ground broke its fall

Needless to say it needs a complete rebuild, and that was with a simple (5 parts only) wooden frame. Luckily I can make a new frame in around 10 minutes and for only a couple of $$$

Have you given any consideration to crash resilience ? Your design looks great but one heavy landing and its not going to look like that for long
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Old Jun 02, 2013, 06:16 AM
Team JR
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Always design to fly, never to crash. If you design something to withstand crashing it'll be very heavy.
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Old Jun 02, 2013, 03:51 PM
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I agree, weight is the enemy of longer flight times. However for stability in wind too light can also be a problem. The arms look good with similar arm design to the Hoverthings HT-FPV frame. Your main body, IMHO looks too heavy unless your were to use large low KV motors on 4s or 6s batteries. I like your integrated brushless gimbal.

What program are you using to lay up the renderings?
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Old Jun 03, 2013, 09:15 AM
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I will use 4 Sunnysky 2814-11 KV 700 with 4s Lipo and 12x6 props.

Weight for a full 1200x600mm birch plywood sheet is 1,4kg (3mm)
I use only 60% of the sheet, the frame will be around 800g without glue.

I use adobe-illustrator to draw every items and send files to laser-cutting factory.
My brother help me for design, and export items from illustratior to z-form and cinema4D for pre-assembling and 3D preview.
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Old Jun 03, 2013, 11:05 AM
Lead Zeppelin
Germany
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This is a clever design and nice computer work, but I really don't think it will have the strength you need, especially for a quad this size (not a micro quad). Remember the Hoverthings FPV frame is made from G10, which is extremely strong. 3mm plywood will snap like a twig, particularly the area in the arms where there are large cut outs.
I would consider removing more material from the center plates, not from the arms. Nobody who is building their own quad can expect to fly perfectly without some mishaps. Using this design and material I don't think the quad would survive even one less-than-perfect landing. Using G10 or some other high strength material would give you more options in the design.
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Old Jun 03, 2013, 11:20 AM
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You could always start with some solid stock arms and switch to the girders later once you're confident with the frames' abilities.
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Old Jun 03, 2013, 05:08 PM
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Quote:
Originally Posted by flugratz View Post
This is a clever design and nice computer work, but...
Thanks!

Quote:
Originally Posted by flugratz View Post
I would consider removing more material from the center plates, not from the arms.
The reason why i removed material from the arm is targeting a good airflow, not for saving weight. May be i will let the arm full.

Quote:
Originally Posted by flugratz View Post
I would consider removing more material from the center plates, not from the arms.
It's not visible on 3D view but i have a landing gear in carbon that will be fix under the center plate. It hope that will prevent broken arms.
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Old Jun 08, 2013, 03:53 PM
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Hi there,

That īs a nice idea. I have built a frame similar to that and you can see it here- http://www.rcgroups.com/forums/showt...1785969&page=2

The frame is made from 3mm ply and weighs 340gr empty. It was glued together and it is sturdy . Your arms are weak and they will brake for sure. My arms seem to be strong as I kept them short and glued together. The glue makes a big difference when it comes to ply.

Stil waiting for parts to make it fly...
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Old Jun 14, 2013, 09:30 AM
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Ok, I've got all my parts back from lasercutter.

As flugratz suggest me, i reduce the large cut out in the arms to make it stronger.

@danielpetrescu : Are you using "aircraft" plywood or regular one. Aircraft plywood have more layer (5 layers for my 3mm plywood).


Let's start the puzzle.... I will give you the frame's weight as soon as possible.



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Old Jun 14, 2013, 11:04 AM
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Coolest. Tinkertoys. Ever.
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Old Jun 15, 2013, 04:07 PM
Lead Zeppelin
Germany
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That looks very cool. I am very curious about how it turns out.
What kind of glue are you using?
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Old Jul 02, 2013, 09:28 AM
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Hi all,

Here is some new pics. Arms are looking strong enought and ready to paint.
The main body need few modifications from the orginal plans (of course )



The blind nuts for the foldable arms



I've try to put stuff on board to see if i have enough room.



And finally it's look like this.... not so bad.



And the gimbal



Any comments, suggestion will be welcome.

@flugratz : I use cyanoacrylate glue from HK
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Old Jul 02, 2013, 06:21 PM
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I like Woody.
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Old Jul 11, 2013, 06:46 AM
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Some news of my woody ;-)
The main frame with gimbal and landing gear support.
And first balance test for gimbal test.

Painting first layer...
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