B275
OTHER:
Mechanics - Casting
OTHER: Helicopter - Outside - Intermeshing - Kaman - K-MAX ~ Transmission
Outside Helicopter
Helicycle:
The main gear case is a 356-T6 aluminum casting.
New Horizons'
Propeller Speed Reduction Unit planetary gear case is made from 6061 T6
Calvert:
The proposed housing is cast magnesium-zirconium alloy.
BO 105:
The main rotor transmission consists of a magnesium casting.
Web Pages:
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National center for excellence in metal working technology - casting |
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NORTH AMERICAN DIE CASTING ASSOCIATION |
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Casting material properties. |
Local Page:
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Properties of materials. Presently just metals, for use in power train components. |
(1) From e-mail and not yet looked into.
Dave,
I was just looking at the material properties page from this web site. I found that when I calculated Poissons ratio my numbers don't always agree with the published numbers. I am using the formula for the Poisson's Ratio as follows:
Modulus of elasticity divided by two times the shear modulus minus 1.
For instance Tungsten is given a Poissons of .28 where as I calculate about .14
Aluminum allloy 2024-T4 is given as .33 were as I calculate .29.
I am not sure which numbers are wrong but something is wrong.
Youngs modulas looks ok so it could be the shear modulas or the formula is used is incorrect.
SynchroLite & UniCopter
Looks like Aluminum 356-T6, Sand Cast is the way too go, at least initially. Dimensional tolerances of 1/16" are typical. If, for some strange reason, there was to be volume then Aluminum 356-T6, Permanent Mold Cast could be considered since it has higher values and lower dimensional tolerances.
Outer aluminum housing for bearings should have a bore 0.0002" smaller than in steel.
This note should go on a [Housing] or [Machining] web page.Magnesium.???
Suppliers:
See rough quote from Alpine Non-Ferrous Foundry in Vancouver in file folder.
From rec.aviation.rotorcraft:
Here is an interesting article on NASA 398 Silicon-Aluminum Alloy:
http://space.com/news/astronotes-1.html
http://www.nttc.edu/techmart/technology.asp?technology_id=27
Apparently, it offers much higher strength and hardness at high
temperatures.
What sort of new applications could this be used for? They list a few,
but can anyone speculate on any others?
I was thinking that in addition to piston engines, that perhaps
turbines might be another area.
sanman
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Sorry to burst your bubble, but this is a CAST alloy, and I for one would
not fly in anything that incorporates cast structural parts (castings are
prone to porosity), so I would limit 398 to things like pistons or accessory
cases. Forged parts are far superior to any cast parts, regardless of the
alloy system (iron, nickel, cobalt, aluminum, whatever). Castings are used
when cost is more important than strength, or for materials that just can't
be forged.
The turbine manufacturers are exploring the use of composite compressor
vanes and that's about the only zone where aluminum could be used - but not
cast aluminum.
Best regards,
Rob Housman
Europa XS Tri-Gear
_________________
I don't think you will ever fly without cast parts unless it's a piston
engine. All the hot section blades and vanes are cast. Just try and make a
single crystal wrought blade :-). And yes there are airframe structural
castings as well. Did you know the SSME turbo pumps are made from many
castings as they are more reliable than fabs?
"Rob Housman
_________________
Typical helicopter transmissions are cast of magnesium or aluminum. The
main frames (principal structural components) of several very modern
turbine engines are cast aluminum. These cast Al frames replaced the
forged and welded titanium parts on the predecessors of these engines.
Cast airframe fittings are not uncommon.
The in-process inspection requirements (x-ray, etc.) for cast parts are
necessarily very stringent, but for complex metallic components,
casting, even with aluminum, can be a very smart choice.
Comment in Article:
... an aluminum casting (very low endurance limit - on the order of 4,000 psi for rough grooved material).
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Last Revised: February 4, 2007