4 metre span built up thermal plank build thread. - RC Groups
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Nov 29, 2016, 03:41 PM
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Jim.Thompson's Avatar
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4 metre span built up thermal plank build thread.


I have been musing over the construction of a large built up wing for some time. Much of this inspiration was gained from my recent %30 scale Klemm petrol powered model build, strange to say.
This is a follow on from my other thread here:

https://www.rcgroups.com/forums/show....php?t=2780761

the concept at this stage is to build a plank large enough to make it easy to achieve a low wing loading and to fit the following brief:

1. No balsa required in the entire build. - I have a bad balsa allergy and besides, it has become very expensive to buy.
2. Cheap to build using commonly available materials wherever possible.
3. Be strong enough to handle a medium non-competition winch launch.
4. Employ a construction method using hot wire cut foam ribs, at least for half of the wing.
5. Use a PW106 reflexed airfoil.
6. Have a conventional sheeted "D" box wing frame using 1.5 mm Pauwlonia or Hoop Pine or Douglas Fir (probably the latter).
7. Covering to be fabric store bought polyester "Pongee" dress lining.
8. Doped with home made scrap EPS foam dissolved in lacquer thinners. - Tests have been done and are very promising.
9. No paint will be required, as the Pongee is available in white and several colours.
10. Pocket hinges for the control surfaces - I swore I would never do them again after the Klemm build, but have figured out a easier way to assemble them. The hinges in the elliptical section will be a challenge though - more about that later.

I will attach a .jpg file of one of my first drafts of the wing planform.
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Nov 29, 2016, 04:40 PM
An itch?. Scratch build.
eflightray's Avatar
Nice Spitfire wing


Dihedral ?, are you intending ailerons or drag rudders ?

Vertical stabs ?


Ray.
Nov 29, 2016, 05:44 PM
supreme being of leisure
ZAGNUT's Avatar
only flying wings i've ever done were a big batch of "walk along" gliders for class projects at my children's school...cutting a big stack of 1mm EPS sheets was a lot less fun than i thought it would be. from what i remember they were less stable when dihedral was added.
Nov 29, 2016, 09:25 PM
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Jim.Thompson's Avatar
Quote:
Originally Posted by ZAGNUT
........................................ they were less stable when dihedral was added.
Yes, the dihedral and polyhedral is very much under review. I expect it would pitch up with increased speed. I would like a slight amount though; I might reduce it and take another look and talk about it. I could also consult the airfoil designer; Peter Wick.
Nov 30, 2016, 01:56 AM
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Jim.Thompson's Avatar
Quote:
Originally Posted by eflightray
.............................

Dihedral ?, are you intending ailerons or drag rudders ?........
Ailerons on the outer panels and elevons on the inner panels. Set up as a four servo plank. I have had a fully moulded four servo slope plank that went very well that way. The entire trailing edge functions as elevator and the ailerons are mixed to the inner control surfaces @ about 30% deflection.
Quote:
Vertical stabs ?
Ray.
The plan is to have a conventional plank fuselage with a vertical fin. The original R2 had a rudder; I might even consider one but don't think it will do much. Might just offer a bit of yaw balance in turns.
Dec 01, 2016, 12:03 PM
Registered User
Quote:
Originally Posted by Jim.Thompson
Yes, the dihedral and polyhedral is very much under review. I expect it would pitch up with increased speed. I would like a slight amount though; I might reduce it and take another look and talk about it. I could also consult the airfoil designer; Peter Wick.
I assume you are familiar with the Windfreak glider?

http://www.outerzone.co.uk/plan_details.asp?ID=5725

It was RE with polyhedral and worked fine that way.


Mark
Dec 01, 2016, 02:50 PM
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Jim.Thompson's Avatar
Quote:
Originally Posted by mmattock
I assume you are familiar with the Windfreak glider?
http://www.outerzone.co.uk/plan_details.asp?ID=5725
It was RE with polyhedral and worked fine that way.
Mark
No, I had not see that one Mark, thanks for the picture. Reports on the other thread indicate the same; it (the dihedral/polyhedral) should be fine.
Wow, the curved polyhedral is sure nice! I would like to do that, but I figure I have enough challenges running with the elliptical planform and pocket hinges etc.
It could be done though!
................(starts thinking...........................).

But of course, it is not possible with ailerons.
Dec 01, 2016, 09:31 PM
Slow builder
_AL_'s Avatar
C'mon Jim. Don't give in so easily.
Eliptical wing, eliptical polyhedral, wing twist for control. No problem......
Dec 01, 2016, 10:22 PM
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Jim.Thompson's Avatar
Quote:
Originally Posted by _AL_
C'mon Jim. Don't give in so easily.
Eliptical wing, eliptical polyhedral, wing twist for control. No problem......
Don't encourage me Al! I've already laid awake at night long enough thinking through the existing problems!..........................
Dec 20, 2016, 01:30 AM
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Jim.Thompson's Avatar

LibreCad file permission problems!


I have lost the original .dxf draft drawing. I am drawing in LibreCad and I have had this problem before, many times actually. I need to resolve it once and for all before starting to draw anything again.
Anyone have any clues about this? So far, the LibreCad forums have not been much help. Possibly because I am not asking the right questions or something like that.
Dec 20, 2016, 09:05 AM
AndyKunz's Avatar
OY! I guess Libre liberated the space on your hard drive

Are you using a version control package or making backups somehow as you go?

FWIW, I have been using TurboCAD since it first came out. The "current version" has always been able to open the oldest TurboCAD files, even the pre-Windows flavors. I have never lost a file to corruption. Even though I keep backups religiously (as an engineer, it's just what you do) I've never had to revert to them for anything other than to copy a part out that I may have removed and found I need to have back.

Everybody touts FOS as "you can fix your own bugs" and "more bug free than commercial software" but there's nothing like PO'd customers to make sure that commercial software gets fixed. I've been on both sides of that as both developer and user, and I am now firmly on the side of using commercial packages for my mission critical tools.

BTW, sorry to hear of your losses.

Andy
Dec 20, 2016, 11:13 AM
Registered User
Quote:
Originally Posted by Jim.Thompson
I have lost the original .dxf draft drawing.
Has the file has gone missing, or it is there but you are unable to open it now? I have no idea on the LibreCAD, I use AutoCAD and Solidworks myself.


Mark
Dec 20, 2016, 03:20 PM
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Jim.Thompson's Avatar
Quote:
Originally Posted by AndyKunz
................................................

Are you using a version control package or making backups somehow as you go?
.................................................. .................................................. ..............................................
.

I don't understand this question Andy, sorry.

Quote:
Everybody touts FOS as .................................................. .................................................. ......................
FOS ?
Please indulge this old timer with a legend to the first use of all acronyms. Otherwise, I am left shaking my head in bewilderment.
But thanks for the reply.

Andy[/QUOTE]

Quote:
Originally Posted by mmattock
Has the file has gone missing, or it is there but you are unable to open it now? I have no idea on the LibreCAD, I use AutoCAD and Solidworks myself.

Mark
I am using Linux operating systems Mark. I do have a Win7 and Win10 partition, but like to avoid using them. I also have AutoCad installed on one of them. If I was serious, I would make an effort to learn that and use it, I am just a bit lazy and slowing down a bit these days.
Dec 20, 2016, 05:25 PM
Registered User
Quote:
Originally Posted by Jim.Thompson
FOS ?
I think Andy meant FOSS: https://en.wikipedia.org/wiki/Free_a...ource_software



Quote:
Originally Posted by Jim.Thompson
I am using Linux operating systems Mark. I do have a Win7 and Win10 partition, but like to avoid using them. I also have AutoCad installed on one of them. If I was serious, I would make an effort to learn that and use it, I am just a bit lazy and slowing down a bit these days.
The reason I ask is I was wondering if it was a file opening problem if someone else could try opening it for you and saving to a new name to give you access again?


Mark
Dec 20, 2016, 07:25 PM
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Jim.Thompson's Avatar
Quote:
Originally Posted by mmattock
.................................................. ........

The reason I ask is I was wondering if it was a file opening problem if someone else could try opening it for you and saving to a new name to give you access again?

Mark
Ok, Mark, thanks. I will boot my other computer (which has the file) later and see if it is still there.
Also, I wonder if the .jpg file I posted earlier can be converted back to .dxf. Do you know?


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