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Nov 25, 2012, 05:02 PM
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mavlo77's Avatar
Another update.... My goal for this weekend was to finish the whole wing... Didn't quite succeed...

But anyhow.... good thing is that the flaps system works. Next step is installing motor wires, electrical wiring for navigation and landing lights and then close the middle section with a top skin.
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Nov 26, 2012, 04:08 AM
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serjuro's Avatar
Nice work, Mavlo..................
Nov 26, 2012, 09:28 AM
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warhead_71's Avatar
Nice work Mavlo. I just wanted to share with this thread my method for making a built-up foam wing. I have started using multi-spar construction instead of multi-rib construction... it goes together much quicker and it leaves natural channels in the wings for running your wiring (motors, servos, LEDs, etc). In these types of foam wings, the ribs only "shape" the airfoil, but add nothing to the strength of the wing. The multi-spars add stiffness as well as shape the wing.



On this particular model I still used LE ribs, so it's a bit of a hybrid, but it could have been built using nothing but spars. The multi-spars are more resilient to wing twist and of course make the wing much stiffer across the span.

https://www.rcgroups.com/forums/show...8&postcount=35

https://www.rcgroups.com/forums/show...&postcount=192

https://www.rcgroups.com/forums/show...&postcount=197
Last edited by warhead_71; Nov 26, 2012 at 09:35 AM.
Nov 26, 2012, 11:32 AM
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mavlo77's Avatar
Thanks both for your comments!

Also thanks for the idea of multi spar wing instead of multi rib. This is something to consider for the next time. For now I finish the way how I started. But I must admit that the torsion / twisting is a bit of a concern for me. So I was considering another full span spar, until AK68 assured me that the top skin will provide the remaining torsion stiffness. The spanwise stiffness feels very adequate for me.

But I like your work in the links, the multi/box-box kind of shape defines the the main shape, and the foam folds around it. Now with my approach the wing skin puls and deforms the wing if it's not carefully glued...
Nov 26, 2012, 12:49 PM
Always Ready!
warhead_71's Avatar
FYI: It's the bottom skin that is in tension when the plane is in the air -- so you need to run your packing tape (or whatever you use) on the bottom of the wing to keep it from stretching under load. The top skin is in compression -- so tape doesn't do a lot unless you are flying inverted -- you need something good in compression, like wood longerons. Regarding torsion/twisting in a multi-spar wing vs. multi-rib ---- the ribs themselves do little to prevent twisting - they only provide "shape" to your airfoil (and a thicker airfoil reduces twisting in and of itself). It's the shear-webbing of the outer skins working in conjunction with the spars that create a series of box-beams to make a box-girder (or I-beams - depending how you cut it). Box-beams are good at resisting twisting.

Triangle beams might work even better, but would be a lot more complicated to build.

The Republic Seabee RC3 is essentially ribless.

More RC3


_
Last edited by warhead_71; Nov 26, 2012 at 01:06 PM.
Dec 24, 2012, 11:47 AM
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mavlo77's Avatar
Thanks Warhead!

Another update from my side. All lights are installed and wired. It's now time to cover the the outer wing sections with a top skin. I try to do this tomorrow.

Then I need to install the flaps. I wait for this until I have installed the top skin on the outer wing sections because otherwise the wing can't be laid flat on the table (flap hinges under the wing).
Jan 01, 2013, 06:12 AM
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mavlo77's Avatar
The wing is now covered, except for the middle section. For me this was the most critical part. I was worried that the stresses in the top skin would twist the wing. But it didn't happen! The skin is just glued now, some sanding and finishing is required still. Also I need to cut out the landing lights from the LE.
Jan 19, 2013, 05:43 PM
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mavlo77's Avatar

Major update


Today I closed the wing. Everything is functional.

Electrical system is also working. It has a redundant system. Will post some more details later.

Now I need to finish some small details like:
- Fix small wing piece between flaps and ailerons
- Sand the wing to match all skins
- Close the gaps between the skin panels
- Landing light cover
- Wing tip navigation lights cover
- Motor pods
- Trailing edge of wing tips
Jan 19, 2013, 07:21 PM
Row 0, Seat A
G550Ted's Avatar
Looking great, Mav! Anxious to see the completed project.

Ted
Jan 20, 2013, 02:29 AM
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serjuro's Avatar
Great work Mavlo, it proofes that you have ,,eyes for details''.
The only thing that you will not use are the flaps, unless your bird will get heavy and thus more landing speed.....This I say after I flew my twin and mine flared nice and easy, I use to land almost vertical.......LOL.
Jan 20, 2013, 06:48 AM
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ak68's Avatar
@mavlo77: Congratulations on the detailed progress! Nice update. Good work needs time.. as they say over here. Some small details (adding fuse ) and she is ready for maiden! Nowadays water is too hard for a maiden anyway.
Looks like things fit like a glove. Good to see things end up according to plan. Those sharp pic's say more than a thousand words. Wish you all the best mounting the motors and some other details!
Jan 20, 2013, 05:14 PM
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mavlo77's Avatar
Thanks all!

@serjuro, hopefully I have some fun with the flaps... most of the building time of the wing went into the flaps... ... Actually I read somewhere else from Roland (the designer) that he was positive about the effect of flaps. I also have a Funcub with flaps. This low wing loading cub also doesn't need them, but on the other hand I like the very steep full flap approaches for landing. In the end I always use them. So we'll see. My PT2 will be a bit heavier than average too (landing gear).

@ak68, thanks ... time flies when building (and having fun).... I just cut out the motor pod parts. If all goes well, I expect first motor test runs this week.
Jan 20, 2013, 06:26 PM
Row 0, Seat A
G550Ted's Avatar
Quote:
Originally Posted by mavlo77
Thanks all!

@serjuro, hopefully I have some fun with the flaps... most of the building time of the wing went into the flaps... ... Actually I read somewhere else from Roland (the designer) that he was positive about the effect of flaps. I also have a Funcub with flaps. This low wing loading cub also doesn't need them, but on the other hand I like the very steep full flap approaches for landing. In the end I always use them. So we'll see. My PT2 will be a bit heavier than average too (landing gear).

@ak68, thanks ... time flies when building (and having fun).... I just cut out the motor pod parts. If all goes well, I expect first motor test runs this week.
Just to note. Those "motor pods" are called nacelles.

Again, excellent work and looking forward to your nacelle build pictures.

Ted
Jan 22, 2013, 03:21 PM
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mavlo77's Avatar
Thanks Ted for correcting, nacelles indeed. From now on I will carefully choose my words.... .

I will post an update soon.
Jan 22, 2013, 03:56 PM
Row 0, Seat A
G550Ted's Avatar
Double post, sorry.


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