[450] K1FSY Mast Strength Analysis

[John Foege]

Results below also attached as *.TXT file for better formatting/readability.

Analysis of Antenna Mast Strength
----------------------------------

Produced for: K1FSY
Performed by: W1QEX
Date: 11/15/2013

All calculations assume:
* Single M2-9SSB antenna with 1.2 ft^2 cross sectional wind loading area is
at top of mast
* 1-1/4 Trade Size EMT (1.51 in. OD / 0.065 in. nominal wall thickness)
* 36,000 PSI elastic yield strength / 58,000 absolute tensile strength
(standard EMT conduit)
* Antenna is broadsided into the wind for maximum wind contact surface area
* All wind speeds are rounded to the nearest whole mph value
* Point of failure is at thrust bearing / top of tower and mast interface

Case #1
-------
* Mast protrudes 20' above thrust bearing

Results:

Bending stress of 35,908 psi occurs @ 45 mph wind speed. Wind speeds in
excess of
45 mph will exceed the elastic yield strength of EMT conduit, resulting in
an irreversible
bending of the mast.

Bending stress of 57,612 psi occurs @ 57 mph wind speed. Wind speed in
excess of 57 mph
will exceed the absolute tensile strength of EMT conduit, resulting in
breaking of the mast.

Case #2
-------
* Mast protrudes 17' above thrust bearing

Results:

Bending stress of 36,194 psi occurs @ 51 mph wind speed. Wind speeds in
excess of
51 mph will exceed the elastic yield strength of EMT conduit, resulting in
an irreversible
bending of the mast.

Bending stress of 58,792 psi occurs @ 65 mph wind speed. Wind speed in
excess of 65 mph
will exceed the absolute tensile strength of EMT conduit, resulting in
breaking of the mast.

Case #3
-------
* Mast protrudes 15' above thrust bearing

Results:

Bending stress of 36,369 psi occurs @ 56 mph wind speed. Wind speeds in
excess of
56 mph will exceed the elastic yield strength of EMT conduit, resulting in
an irreversible
bending of the mast.

Bending stress of 58,462 psi occurs @ 71 mph wind speed. Wind speed in
excess of 71 mph
will exceed the absolute tensile strength of EMT conduit, resulting in
breaking of the mast.

Case #4
-------
* Mast protrudes 10' above thrust bearing

Results:

Bending stress of 36,125 psi occurs @ 74 mph wind speed. Wind speeds in
excess of
74 mph will exceed the elastic yield strength of EMT conduit, resulting in
an irreversible
bending of the mast.

Bending stress of 58,4291 psi occurs @ 94 mph wind speed. Wind speed in
excess of 94 mph
will exceed the absolute tensile strength of EMT conduit, resulting in
breaking of the mast.

73s de W1QEX
John
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Analysis of Antenna Mast Strength
----------------------------------

Produced for: K1FSY
Performed by: W1QEX
Date: 11/15/2013

All calculations assume:
* Single M2-9SSB antenna with 1.2 ft^2 cross sectional wind loading area is at top of mast
* 1-1/4 Trade Size EMT (1.51 in. OD / 0.065 in. nominal wall thickness)
* 36,000 PSI elastic yield strength / 58,000 absolute tensile strength (standard EMT conduit)
* Antenna is broadsided into the wind for maximum wind contact surface area
* All wind speeds are rounded to the nearest whole mph value
* Point of failure is at thrust bearing / top of tower and mast interface

Case #1 
-------
* Mast protrudes 20' above thrust bearing

Results:

Bending stress of 35,908 psi occurs @ 45 mph wind speed. Wind speeds in excess of 
45 mph will exceed the elastic yield strength of EMT conduit, resulting in an irreversible 
bending of the mast.

Bending stress of 57,612 psi occurs @ 57 mph wind speed. Wind speed in excess of 57 mph
will exceed the absolute tensile strength of EMT conduit, resulting in breaking of the mast.

Case #2 
-------
* Mast protrudes 17' above thrust bearing

Results:

Bending stress of 36,194 psi occurs @ 51 mph wind speed. Wind speeds in excess of 
51 mph will exceed the elastic yield strength of EMT conduit, resulting in an irreversible 
bending of the mast.

Bending stress of 58,792 psi occurs @ 65 mph wind speed. Wind speed in excess of 65 mph
will exceed the absolute tensile strength of EMT conduit, resulting in breaking of the mast.

Case #3 
-------
* Mast protrudes 15' above thrust bearing

Results:

Bending stress of 36,369 psi occurs @ 56 mph wind speed. Wind speeds in excess of 
56 mph will exceed the elastic yield strength of EMT conduit, resulting in an irreversible 
bending of the mast.

Bending stress of 58,462 psi occurs @ 71 mph wind speed. Wind speed in excess of 71 mph
will exceed the absolute tensile strength of EMT conduit, resulting in breaking of the mast.

Case #4 
-------
* Mast protrudes 10' above thrust bearing

Results:

Bending stress of 36,125 psi occurs @ 74 mph wind speed. Wind speeds in excess of 
74 mph will exceed the elastic yield strength of EMT conduit, resulting in an irreversible 
bending of the mast.

Bending stress of 58,4291 psi occurs @ 94 mph wind speed. Wind speed in excess of 94 mph
will exceed the absolute tensile strength of EMT conduit, resulting in breaking of the mast.
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