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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)
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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:
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
| 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
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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
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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)
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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)
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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)
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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
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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)
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Density: (1.148 +- 0.032) g/cm³
Other names: Nylon
Similar to Polypropylene, but even
more flabby. Besides it takes up humidity. |
Polycarbonate (PC)
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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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