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A short story of materials science

Introduction

On this page you can get some information about what materials you can use for LDbooms. We try to refer every material that is used or we know of. The density declared in the chapters is calculated by Tibor measuring volume and weight of samples.
If you have additional knowledge or disagree, please contact us.


Wood (Birch Cross Ply 10 layers on 5mm of Finland)

Density: (0.801 +- 0.026) g/cm³
You know wood, the thing trees are made of. It´s a great material to begin LDthrowing. Herb Smith made 100m throws with wood. And Michel Dufayard, too and ... 
Advantage Easy to work with.
The glue layers show how accurate you are working.
Disadvantage Breaks at stronger throws/if there´s too much lead on it.
Sensitive to humidity
Low Density

Paxolin

Density: (1.359 +- 0.043) g/cm³
Other names: Pertinax, Bakelite, Hartpapier, ...
Commonly used for LDBooms. It´s made out of paper impregnated with phenolic-formaldehyd resin. If you´re interested in chemical formulas, watch this:
 
chemical formula

There are different types of Paxolin. Be sure to use to paper impregnated type as the cloth-type [Density: (1.314 +- 0.044) g/cm³] is not stiff enough (although it is able to resist a higher impact than the paper-type).
 
Paper impregnated Cloth impregnated
Advantage Very stiff
Interesting density
Cheap
Disadvantage Very dangerous dust producing; Health (Cancer) risk
Can break if there is too much lead (20g+) or the boom is not thick enough
Attracts water and looses in the course the stiffness (always seal the boom with a coat of water resistant color)
Needs powertools at least for cutting

Glassfiber/Epoxy Composite

chemical formula
yellow light green
 
Density: (1.794 +- 0.060) g/cm³
Other names: GFEC, G10 
Commonly used for LDBooms. It´s made out of epoxy resin and glassfibers. 

Here are also different types of G10. From the outside you can not tell which quality you have. But after your first boom you know it. If your boom gets habitual tuning after a few (say five) throws, then you have the bad thing. For us the yellow type is stiff enough, while the lightgreen type is trash (The color can vary from other manufacturer). There seems to be a G11 type which is even more expensive. Maybe we find out sometime. 

Advantage Stiffness
Strength (we had no fractures up to now)
Toughness (resistant agains severe impacts)
Good density
Easy to shape
Disadvantage Glassdust is also dangerous; Beware
Needs powertools
Special cutting-equippment needed
Can get habitual tuning
UV-sensitive ?
expensive

Carbonfiber/Epoxy Composite

Density: 1.5 g/cm³ (not measured by myself)
Be carefull: the fibers are so thin, they can stick in your body and you won´t even feel it, at first. Use gloves and cover all your body. Don´t work without dust-(and gas)mask!
 
Advantage verrry stiff
incredible strength
toughness, almost unbreakable
Disadvantage verrry dangerous dust
Special cutting-equippment needed
needs powertools
verrry expensive 

Aluminium (alloys)

Density: (2.550 +- 0.092) g/cm³
Beware! Very dangerous! Metal booms are not allowed in competitions.
 
Advantage Heavy
Stiff
Disadvantage Did you see Mad Max II?
Needs powertools
Gets easily warped

We only used pure-Al boards, which is very soft and therefore not fit for boomerangs. High-strength Al-alloys, however, are better. Christian Jabet, a frechman, used 'Zicral', a chromium and zirconium alloyed aluminium, for his V-shaped boomerang and made an inofficial world record of 149m. It is said that he had an anvil and a hammer to flatten his boom after crashes. 

Circuitboard

Density: (2.041 +- 0.088) g/cm³ 
What I mean with circuitboard (it's used for Computermainboards and stuff like that.)is a lamination of G10 and coppersheets. This material is quite new to the boomsport. For LD it would be interesting in thickness of 3 to 3.5 mm. Unfortunatly we were unable up to now to acquire such sheets.

Materials not used for LD, but other boom events:


Unsaturated Polyester (UP) Resin

chemical formula Density: 1.25 g/cm³ , reiforced with glass fibers: 1.5-1.8 g/cm³ 
 

Usually, the material is reinforced with glassfibers. We saw it being used for medium-range boomerangs. Density and stiffness is comparable to GFEC. Unfortunaltely, it breaks more easily and is difficult to tune. We have not built LD models with UP-resin, it seems to be an interesting material for this event though.


Polypropylene (PP)

chemical formula Density: 0.9 g/cm³ (not measured by myself)
It´s not stiff. It´s a thermoplast: 

PP is commonly used for short range tribladers, for instance Eric Darnells Tri-Fly. In warm weather it is soft and in cold conditions it gets brittle. There is a Polypropylene material with additional glassfibers. 
Density: (1.174 +- 0.038) g/cm³


Acrylonitrile-Butadiene-Styrene-Copolymer (ABS)

chemical formula Density: 1.0 g/cm³ 
It is a impact resistant Polystyrene. 
 
 

The new Tri-Fly from Eric Darnell is ABS. It is an excellent material for short range boomerangs. It's stiff, machined easily, resistant against humidity and does not loose its shape in warm weather.


Polyvinylchloride (PVC)

chemical formula Density: ~1.4 g/cm³
It is rather heavy for a thermoplast. 

We did not often see PVC used for booms. But why not ? Try it! It is probably especially fit for wind boomerangs, considering the high density. 


Forex

Density: (0.669 +- 0.021) g/cm³
It´s a foamed PVC.
Forex is very light and flabby. It breaks rather easily. Forex is excellent, however, for small fun or beginners boomerangs - easy to throw and catch.

Acrylic glass

chemical formula Density: (1.161 +- 0.040)g/cm³ 
Other names: Polymethylmethacrylate (PMMA), Plexiglass 

 It´s a substitute for glass but less brittle, but still brittle. It is nice to have a translucent boomerang, but otherwise: forget it.

Polyamide (PA)

chemical formula Density: (1.148 +- 0.032) g/cm³ 
Other names: Nylon 

 Similar to Polypropylene, but even more flabby. Besides it takes up humidity.

Polycarbonate (PC)

chemical formula Density: 1.5 g/cm³ 
Other names: Makrolon 

 It is also translucent and used for the fabrication of compact disks. We have no experience with this type of material.

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