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Old Feb 03, 2016, 09:29 AM
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Opinion needed!! First DLG scratch build

Hello all,
This is my first attempt for a DLG, I made it based on Manta V2 Plans.

I made the wing out of 4mm Balsa, sanded to a air foil, and control surfaces using 2mm balsa.

Used 2 mm Carbon fiber rod

Im not sure what to use to glue the balsa together, I used some hotglue to hold bits in place, while the white glue (elmer's brand) settles. Is white glue good for woods?

What are some top tips for building? I really need some badass tips from super experienced guys, because i really want this project to work!!

Btw, How do i make a pod?? I plan to use either a Clone Brick with 2 servos, or 2 micro servos

Im on pretty tight budget, and I really cant afford the fancy composite wings, covering .. .So i made a solid wing.

I really like paper planes as a kid, seeing them glide so gracefully makes me so happy, I hope this mini DLG will do the same

Cheers
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Old Feb 03, 2016, 02:33 PM
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My first DLGs were made using lost foam method for the pod. Basically carving it out of foam, sticking composite cloth pieces to it with 3m77 spray, then saturating with epoxy and then dissolving out the foam after the epoxy cures.

Using a carbon arrowshaft for a boom works quite well too, even though many will say they're not stiff enough. I flew several of my early contest ships with them.

Just build and fly. Make the next one a little nicer than this one... it's a process to perfection.
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Old Feb 03, 2016, 05:40 PM
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I see... Thank you very much for the pod ideas, I will get some 3m 77 spray, epoxy and some composite cloth pieces

How would I Glue the main wings and the horizontal stabliser into the carbon fibre? I am using a circular 2mm CF rod, How do i make sure the wings are perpendicular to the CF rod??

Thank you very much
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Old Feb 03, 2016, 07:26 PM
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Planery,

Those are very nice looking wings. I like to see folks giving building models a try.

Like Tom suggested lost foam is a good method for making pods. Take a look at this set of plans:

http://www.charlesriverrc.org/articl...ite2m/fuse.pdf

This particular model is way bigger than what you are making but I think the drawing gives an idea on how you could make pods. Notice that the pod has 2 wooden bulkheads where the wing sits on top of and where bolts are attached to attach the wing to the fuselage. For your DLG I would have the boom go all the way through the bulkheads and possibly just have the boom go all the way to the nose of the model. You could use the same type of method with smaller bolts or screws for your DLG. If you have the boom go all the way through the fuselage to the front of the fuselage you could mount the receiver brick on top the boom (the ELF is done sort of like that).

Once you have the bulkheads and the boom mounted (you can actually test mount the wing to the bulkheads first to align it) then you get just any foam blocks you can find. Stuff that electronics or toys or whatever is packed in is perfect. You take the foam and kind of cut it into blocks and then attach it with any glue you have (spray adhesive would be fine as would the white glue you show in the picture) to the bulkheads and the boom. The idea is to kind of make a big foam block that is bigger than the bulkheads/boom. Then you can just kind of sand the thing to the shape you like and use the bulkheads as a guide in the sanding. Once that is done you cover it with pieces of cloth (and you can stick the cloth down with spray adhesive if you go light on the spray adhesive) and then paint it with laminating epoxy. Once the laminating epoxy cures you cut a hatch in the pod for where you will install and access the radio gear and you remove the foam either by picking it out or by using either paint thinner or gasoline will dissolve it.

Fiberglass cloth is cheap. I would use 3/4 ounce fiberglass for a model this size. You can get a few square meters of fiberglass cloth for 6 or 8 dollars. Fiberglass cloth can be used for lots of things.

Also I want to mention that I have used the above method to make pods.

Ryan
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Old Feb 04, 2016, 12:47 AM
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This is a tiny glider, so forget anything heavy or it will glide badly and not upwards!
So no to arrow blanks or complicated fibreglass pods and conventional radio gear and even heavy balsa. Even glue counts so no hot glue! Balsa is easy to glue using wood glues including 'white' glue but most sand badly. Balsa cement made from volatile cellulose is easy to sand on joints without damaging the wood and applied sparingly is light.

First step - Weigh everything you have and work out the wing area. Calculate the cubic wing loading (Weight / (Area ^ 1.5). There are many online calculators. Now see how many more grams you can add to get the result under 4. The lower you can go without it falling apart on launching and landing the better it will thermal.

The most efficient form for the boom is a tube, so you could gain a few grams with a 3mm tube. Weight at the back counts enormously as it minimizes weight at the nose, length of nose. A side arm launch is not as critical as DLG for rear moment, so do not make it too long, but the horizontal tail is small (aerodynamic things do not scale down proportionally).

Mount the tail and wings on balsa pylons - sand a semicircle by wrapping the boom with sandpaper. CA onto the boom. Reinforce the boom/wing pylon/wing junction with a scrap of 3/4 ounce glass and CA.

Seal balsa surfaces with a thin layer of polyurethane then wipe most of it off. Only minimum paint on tips for orientation. If the wing is too heavy balsa then cut circular holes in rear half and patch with lightest laminating film 1.2-1.5mil, also good for hinging and local reinforcement like launch wing tip.

Good idea to extend boom to nose and hang gear off it. Pod only needs to be aerodynamic, not structural. A PET plastic blown pod is ideal. Make a blank of wood and heat shrink a light PET bottle over it, or find similar premade scrap object like toothbrush holder. Otherwise a simple balsa sheet box with glass cloth or laminating film reinforcing. This is better than adding dead weight to the nose if that is the way the design works out.

Use pull spring controls and lightest gear. A cheap brick like the FlySky protocol WLToys V911/F929/F939 and a small Lipo should come to around 10grams.

A better bet would be to make an existing design of a similar size of which there are many.
Using sanded extruded foam instead of balsa is easier and lighter and cheaper.
Attached are some small HLG plans but much better luck can be had with larger span gliders (over one metre) that will cost little and have less stringent weight requirements. Making a small glider is much harder!
Some common beginner balsa based gliders that can be made from plans available on this forum are Mimi, Icarus, Gambler, QFII, and a new Manta like full size WEvolution.
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Old Feb 04, 2016, 06:14 AM
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Rusty, fiberglass can be made very light if it is just serving as the aero shell. 2 layers of 3/4 ounce glass won't weigh much.

Ryan
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Old Feb 04, 2016, 08:56 AM
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Thank you very much for you help!!

I've made a rubbishy pod with foam. Im using a ar6400 clone, with a 150 mah batt

the plane weights around 32grams with battery

Wing span is 400mm

I used the 'white' glue here, but I will be getting CA glue, CA kickers, fibre glass cloth, CF tubes and rods, and foam

Really appreciate your help!!
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