Espritmodel.com Telemetry Radio
Reply
Thread Tools
Old Sep 07, 2013, 11:43 PM
Entropy is happening!
Jim.Thompson's Avatar
Bellingen NSW Australia
Joined Aug 2008
6,663 Posts
Thanks Tom, but I cannot open that video.
If you can find a pictorial easily, please link one for me. I'm just reading up on the basics with view to making my first DLG wing.
Jim.Thompson is offline Find More Posts by Jim.Thompson
RCG Plus Member
Latest blog entry: Yet another light plank!
Reply With Quote
Sign up now
to remove ads between posts
Old Sep 08, 2013, 09:30 AM
Father of Fr3aK, DLG Pilot
tom43004's Avatar
USA, OH, Worthington
Joined May 2002
6,670 Posts
Can't find the original pics, but all info and some pics are in this short thread:

http://www.rcgroups.com/forums/showthread.php?t=1450296
tom43004 is offline Find More Posts by tom43004
Reply With Quote
Old Sep 08, 2013, 11:33 AM
Registered User
bommerglide's Avatar
United States, CA, Oxnard
Joined Sep 2006
56 Posts
I use this works great two different sizes

http://shop.fiberglasshawaii.com/fab...-067-oz-techno
bommerglide is online now Find More Posts by bommerglide
Reply With Quote
Old Sep 08, 2013, 02:13 PM
Entropy is happening!
Jim.Thompson's Avatar
Bellingen NSW Australia
Joined Aug 2008
6,663 Posts
Video

I was able to open and view the video at post #9 ok this morning thanks Tom.
What weight cloth was that you were using?
Or more importantly, what weight cloth would be suitable (when done with the carbon disser -probably 3 k) for my first vac bagged DLG wings? I have 50 gsm and 25 gsm plain weave cloth in stock. (approx equivalent to 1.5 oz and .75 oz respectively).

Nice video and a marvelous technique!

I'll quite possibly start a new thread for this planned project, as it will be a full build and as I'm totally new to DLG, there will be a zillion questions to ask.
Jim.Thompson is offline Find More Posts by Jim.Thompson
RCG Plus Member
Latest blog entry: Yet another light plank!
Reply With Quote
Old Sep 08, 2013, 08:36 PM
Father of Fr3aK, DLG Pilot
tom43004's Avatar
USA, OH, Worthington
Joined May 2002
6,670 Posts
Jim,

I've used 25g/sm before but 50 would be a better choice, especially if you're not super-competitive. Your wing will end up weighing 6-10g lighter with the 25g/sm but I call these "weekender" wings. They flex a bit more and twist a bit more and if you throw harder, they will be spent after a good tough two day contest.

Hangar rash (even installing gear) can be a killer on the 25g/sm wings.
tom43004 is offline Find More Posts by tom43004
Reply With Quote
Old Sep 09, 2013, 12:51 AM
Entropy is happening!
Jim.Thompson's Avatar
Bellingen NSW Australia
Joined Aug 2008
6,663 Posts
That's confirmed my suspicions Tom. Thanks.
Jim.Thompson is offline Find More Posts by Jim.Thompson
RCG Plus Member
Latest blog entry: Yet another light plank!
Reply With Quote
Old Sep 10, 2013, 07:01 PM
let's FLY!
JimZinVT's Avatar
United States, VT, Castleton
Joined Dec 2007
2,056 Posts
Quote:
Originally Posted by bommerglide View Post
I use this works great two different sizes

http://shop.fiberglasshawaii.com/fab...-067-oz-techno
That looks like interesting stuff. I can't find much info on it. Only place I see it is on surfboard websites. What else can you tell us? It's listed as 0.67 oz./yd^2. It looks like carbon disser supported by a glass scrim? What is the spacing between tows? I'm tempted to order a yard or 2, but the shipping may be more than the cost of the fabric.



I saw a link a while ago for a light Kevlar fabric with a carbon disser woven in, but I didn't save the link. Anyone know where that can be found? I think it was pretty expensive stuff.
JimZinVT is online now Find More Posts by JimZinVT
Reply With Quote
Old Sep 10, 2013, 08:10 PM
Registered User
bommerglide's Avatar
United States, CA, Oxnard
Joined Sep 2006
56 Posts
The scrim is nylon and if you look there are two sizes this showing the small
1/2 oz.@45 with the carbon under on 1lb foam
bommerglide is online now Find More Posts by bommerglide
Reply With Quote
Old Sep 11, 2013, 10:01 AM
Father of Fr3aK, DLG Pilot
tom43004's Avatar
USA, OH, Worthington
Joined May 2002
6,670 Posts
The angle of the carbon is highly important. If it's not very nearly 40-45 degrees, the fiber will not be carrying the loads, but rather the epoxy. This material has very little fiber in the scrim (oriented 0/90) and has the carbon oriented at a <30 degree angle. I don't want to say it's useless for what we do, but it's probably not much more than decorative at this point... especially when oriented chordwise. If there's a light glass layer used in addition to this for a finish layer, I'd venture a guess that the glass layer (if on a bias) is providing more torsional stiffness than the carbon.

The 1.2oz kevlar with 1k Carbon tow disser can still be had... here:

http://shop1.r-g.de/4DCGI/ezshop?act...COUNT=37996888
tom43004 is offline Find More Posts by tom43004
Reply With Quote
Old Sep 11, 2013, 03:52 PM
Entropy is happening!
Jim.Thompson's Avatar
Bellingen NSW Australia
Joined Aug 2008
6,663 Posts
Sorry for the offtopic question, but how are the control surfaces cut out of a kevlar bagged wing?
Jim.Thompson is offline Find More Posts by Jim.Thompson
RCG Plus Member
Latest blog entry: Yet another light plank!
Reply With Quote
Old Sep 11, 2013, 05:26 PM
Father of Fr3aK, DLG Pilot
tom43004's Avatar
USA, OH, Worthington
Joined May 2002
6,670 Posts
single edge razor
tom43004 is offline Find More Posts by tom43004
Reply With Quote
Old Sep 11, 2013, 06:17 PM
Entropy is happening!
Jim.Thompson's Avatar
Bellingen NSW Australia
Joined Aug 2008
6,663 Posts
Ahh! Thanks Tom.
Jim.Thompson is offline Find More Posts by Jim.Thompson
RCG Plus Member
Latest blog entry: Yet another light plank!
Reply With Quote
Old Sep 11, 2013, 07:21 PM
Registered User
jbarnhardt's Avatar
United States, WA, Seattle
Joined May 2011
477 Posts
Quote:
Originally Posted by tom43004 View Post
The angle of the carbon is highly important. If it's not very nearly 40-45 degrees, the fiber will not be carrying the loads, but rather the epoxy. This material has very little fiber in the scrim (oriented 0/90) and has the carbon oriented at a <30 degree angle.
Tom, I'd be interested to understand your thinking with respect to the 40-45 degree angle of fibers in a DLG wing. I've thought about this from time to time and it seems like the torsional forces in a wing are such that the optimal angle for reinforcement might not be 45 degrees; specifically, since the spar is providing spanwise reinforcement, perhaps the skins (or disser) should be biased in the chordwise dimension to be more aligned with the twisting loads seen by the wing at launch. I am very ready to admit that I may not be considering this properly from an engineering perspective and you have certainly done *way* more building than I have. But I remain curious as to the justification for 45 degrees being optimal, as opposed to something where the reinforcement properties were more biased in one direction... Thanks for any elucidation you can offer.

-John
jbarnhardt is offline Find More Posts by jbarnhardt
RCG Plus Member
Latest blog entry: Latest creation...
Reply With Quote
Old Sep 11, 2013, 08:55 PM
Father of Fr3aK, DLG Pilot
tom43004's Avatar
USA, OH, Worthington
Joined May 2002
6,670 Posts
John,

I very specifically did NOT say that 45 degrees was optimal.

Notice the disser in my own wings in the attached picture. I use 39 degrees myself after much discussion, debate, and banter in the German forums... and some testing on my part a couple of years ago.

A very shortened version of the argument is that as aspect ratio increases, the optimal disser angle slightly decreases.

There were arguments about variable spacing, variable disser angles from root to tip, etc etc. My belief is that the fibers are useful only in tension for the most part, and only if they're oriented properly. When you think about twisting forces on the wing, you have to consider that the loads are NOT aligned around the quarter chord line axis that aero loads would tend to apply, because the torsional forces aren't strictly a result of lift generation. The thrower imparts most of the evil. It's dependent on throwing style, peg position and a whole bunch of other stuff that's hard to quantify.
tom43004 is offline Find More Posts by tom43004
Last edited by tom43004; Sep 11, 2013 at 09:09 PM.
Reply With Quote
Old Sep 12, 2013, 03:26 AM
Meek A Mouse
Deutschland, BW, Stuttgart
Joined Aug 2004
107 Posts
Quote:
Originally Posted by tom43004 View Post

The 1.2oz kevlar with 1k Carbon tow disser can still be had... here:

http://shop1.r-g.de/4DCGI/ezshop?act...COUNT=37996888
As well as 1k tow, which is available again: http://shop1.r-g.de/ordernumber/205100
gideon is offline Find More Posts by gideon
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Show Me Your Rack jasmiller Flight Accessories 5 Mar 09, 2013 10:49 PM
For Sale Orion F3K DLG - D-Box, Disser with Rohacell! Ekspert5 Aircraft - Sailplanes (FS/W) 0 Jan 10, 2013 10:08 AM
Discussion Show me your Rack (plane rack of course...) kepople Electric Plane Talk 7 Mar 30, 2009 11:10 AM