Cheap, simple foam DLG with good performance

by xardinen | July 25, 2013 | (23) Posted in Projects

 

Hello

I've been very interested in getting my feet wet in the DLG part of this hobby. Earlier this year I was inspired to make my own dlg with cheap parts and building methods. So I drew up a rough plan and created airfoil templates for the main wing.

The result is a 1.2 meter dlg with a hot wire cutted foam wing glued to a carbon boom. The tail fins are made out of depron and tape. Clear packing tape is the only reinforcement to the main wing. Despite it's simplicity it flies great! The launch is straight and it tracks really well. Thanks to the AG35 airfoil it floats well in dead air and thermals great from small bubbles. The rising air from a black sheet metal roof heated by the sun is enough to make this plane ascend into the sky.
The current setup is elevator/ailerons with servos glued to the boom in the nose.

 

Excuse the poor quality video!

I hope that some of you will try building a DLG because flying one is really addictive!

- Find this article & others like it at www.FliteTest.com -

COMMENTS

earthsciteach on July 31, 2013
Love it! I was wondering how practical it would be to scratchbuild a DLG. This will be going on the list of projects. Thanks for posting!
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craftydan on July 31, 2013
Very cool! I'd love a DLG, and one I can make with materials on hand is fantastic!

few questions:
What diameter CF rod are you using?
What thickness of depron for the main wing?
Can you publish your cutting templates (possibly demo video cutting)?
What electronics did you use (rx, battery, servos)?
What's your AUW?

(Sorry about the flood of questions, This has me intriuged!)
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xardinen on August 1, 2013
Im glad you are interested.
-I would recommend a 8mm CF rod.
-The main wing is not in depron, it's white foam (low density, quite weak. totally dependant on packing tape cover).
-I could try to find the templates I used and post them somewhere.
-Electronics: 2x 9g servo. HK 6ch 2.4ghz rx. The batteries are some kind of camera battery. I can measure their weight and size.
-The AUW is around 200g.
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craftydan on August 1, 2013
Thanks for the details.

Could you be more specific about the main wing foam you used? What is it usually used for?

Also did you run your tape across or down the length of the wing?

I'm assuming it's 8mm CF tube, right? If so, how thick is the wall (or the inner diameter)?
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xardinen on August 2, 2013
The wing foam is called EPS80. It's a standard isolation foam here in Sweden. It would be strange if it wasnt available somewhere else. The tape is applied down the length of the wing - starting from root running to the tip of the wing. Apply it to the bottom side of the wing first. The tape will bend the wing in the direction of the side you applied it to. Applying tape to the top side side of the wing last will result in a slight bend in that direction, which will give you a small dihedral. This method compresses the foam a little and makes it more durable and stiff.

Yes, Im sorry I meant CF tube. A rod would be too heavy :). I cant remember the thickness of the wall but a maximum of 1mm should be enough. I've tried with a thinner CF tube (~5mm or so) and it cracked after some power throws.
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azgar on August 1, 2013
Did You mean CF tube?
I've had my Mimi built around 6 mm hollow tube from Hobbyking. It gave up after full year of flying, including some nasty very rough landings.
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xardinen on August 2, 2013
Yes I meant CF tube :). I've cracked a 5mm tube already. The hard landings isnt the real problem, I think its the force applied to them at launch. Btw, the Mimi seems to be an awesome flyer.
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azgar on August 2, 2013
Mimi is a great flyer indeed! Highly recommended for every DLG beginner.
As far as I noticed, CF tube holds on launching g forces pretty well. But hits on hard landings introduce cracks at stress concentration points (near the wing fix, in my case) and there it breaks on a next launch. I may be wrong, though, just my opinion.
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xardinen on August 2, 2013
That sounds like a very possible theory. The force on those stress concentration points are amplified both in hard landings/crashes and launches. Making it a very critical zone.
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squishy on July 31, 2013
What a great way to get into DLG, great idea..
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cgetman02 on July 31, 2013
Excellent job! I'm interesting in more details also!
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Winger on July 31, 2013
Yes, great job indeed. More details, PLEASE.
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Antheman54 on July 31, 2013
They fly great keep up the cool builds
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colorex on July 31, 2013
Hello fellow swede.
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xardinen on August 1, 2013
Thanks for the response! Im glad you find this article interesting. If you post what details you want/need I'll try to get em. Otherwise I will post some more general details (and maybe some pictures) this weekend.
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Paulshort on August 1, 2013
Hi there i tried to build on using foam that came off packaging a fridge i shaped it with a wood rasp and covered it in packing tape and used a dowel rod but sadly i was flying it in to much wind and broke the dowel also witch way did you run the packing tape. i wanted a dlg so bad that i cut the motor mount off a nine eagles sky runner and put a discus peg in the wing and it flies great.

i am interested in more info


keep it up
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xardinen on August 2, 2013
It sounds like you should invest in a foam cutting tool, otherwise it's hard to achieve any decent airfoil (which DLGs are very much dependant on). I'm using a scrap PSU from an old computer to heat up a wire for cutting, it works like a charm. I ran the tape lengthwise - from root to the wingtip. Cover the bottom side first. You should try building one of these. Put some effort into it and it will pay off, I promise.
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Sirglider on August 2, 2013
Brillant!
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Paulshort on August 2, 2013
Hi there i have already tried cutting foam wings with a hot wire but they always get to much taper
do you think you could build one with a kf airfoil out of foamboard also i am using a guitar string for my hotwire at the moment so it would be cool if you made a video of your hotwire.

thanks for the cool design

Paul age 12

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Paulshort on August 3, 2013
Hi there I am now building one I got my Hotwire sorted and it works great. I am using a piece of angle aluminium as my tail boom and will put a delta mixer on the throttle channel so it has air brakes thinly problem is I have two weeks to complete it as there is going to be a dlg contest.
Advise wanted
Paul age 12

Thanks
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xardinen on August 5, 2013
Im not sure if the angle aluminium is suitable for the task. It will either be too heavy or bend too easy in a launch/crash. You should try to get a CF tube. I've sourced them from some fishing rods costing 3 dollars.
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Paulshort on August 5, 2013
The problem with that is that I live in New Zealand and model stuff is way more expensive and angle aluminium is what I have on hand. I might try the second hand shop for fishing rods can you use arrow shafts that are 5mm


Thanks
Paul



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xardinen on August 5, 2013
I think that an arrow shaft, despite being 5mm is a better choice than aluminium.
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Paulshort on August 5, 2013
the problem with that is the arrow shaft is only 1 meter long
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xardinen on August 6, 2013
The total length of the boom is supposed to be under 1 meter. Around 85cm actually.
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tramsgar on August 7, 2013
Nice, thanks! Looking forward to the build video =).
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xardinen on August 8, 2013
If I can spare the time I'll make a build video and post it here.
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InflytRC on August 7, 2013
Brilliant! You, sir, are a genius!

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xardinen on August 8, 2013
Thanks alot. I hope that this will inspire more people to make their own foam DLG and try this part of the hobby.
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joann69 on August 18, 2013
Hi, I've been building swappables for the past several months and I'd like to build a glider. Could you please tell me what DLG refers to? Until I started reading your posts, I'd never heard of a DLG. Thanks
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xardinen on August 19, 2013
DLG refers to Discus Launched Glider. A type of glider which is hand launched like a discus.
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Driveandairsmash on August 29, 2013
I really like this plane but think we can get some plans for it? I really like DLG becuase i like to use 9 v batteries to power then and they work perfect!! So if you could get those plans on here that would be AWSOME!
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rc brian nj on September 29, 2013
The plans are above in one of the images . you can resize that image if you need a template but with the measurements you can build without one. Keep in mind the author used a hot wire cutter for his wing but you can cut yours with a razor and sand the shape into the foam. Be sure to look into wing shaping to create the airfoil with the correct lift!

Thanks Winkdogg
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rc brian nj on September 29, 2013
I to was looking for a cheap way to see if DLG was for me ! Great glider great plans great job! Thanks for sharing , now that I know I like dlgs I am going to start building more hi-tech versions! I might even try my hand at making my own carbon fiber wing! Thank you for the inspiration and all the work you did putting this glider together , without you I may have never tossed my own :) Its pretty flat where I live and average wind speed is around 7 mph so there are really no gliders around but I think I might change that . Lots of guys I fly with are now designing , building and buying DLG's.

Thanks , Winkdogg
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xardinen on October 29, 2013
Im glad that I could inspire you building your own! Thanks for trying out my design.
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Aronnax on November 9, 2013
I just build my first hot wire cutter a few days ago, so I'm nearly ready for this ;-)

I have some questions regarding the wings and the airfoil.
I've found the airfoil here:
http://airfoiltools.com/airfoil/details?airfoil=ag35-il

So it seems to be flat on the bottom. In the photo where you parked your plane so nicely in the tree the airfoil looks different or attached at a different angle. Could you please clarify this.

From your description above I understand that you bend the wings a bit with the tape you apply. But it looks like there's also an angle in the center. Didi you make the wing of two pieces and assembled them with a slight angle?

Thanks for your inspiration and the plans
René
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grifflyer on September 4, 2016
does the tail have to be like that all separated or can it be one piece like the tiny trainer

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knowaczykk on February 3, 2018
hello,
are the wings separate or one. if its one how did you put the dihedral in it using the tape. also where did you run the rod through?
thanks
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xardinen

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Cheap, simple foam DLG with good performance