[Moon] Calculating the foundation for a dish mount

[Zdenek SAMEK-OK1DFC]

Conrad, your calculation is for bend force in bottom part of mast, not 
torque.

So if you will have mast diameter 250mm pipe, wall 10mm than bend force is 
136 MPa and coeficient of security 1,3  means for static load. For dynamic 
load is this situation much worse and you will be with coeficient bellow 1. 
So 3300mm long mast has to be stronger, or made as cantilever beam.


-- 
Zdenek - OK1DFC
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---------- Původní e-mail ----------
Od: Conrad PA5Y via Moon <moon at moonbounce.info>
Komu: moonbounce_info <moon at moonbounce.info>
Datum: 15. 1. 2020 13:07:07
Předmět: [Moon] Calculating the foundation for a dish mount 
"It is time for me to start preparing things for a dish mount for a 5m dish.
I would like to properly calculate the foundation requirements, it seems to 
me that people guess here and usually use too much concrete. I would like to
have proper calculations and hope that someone can help me. I may use ground
screws and so it will really help me to calculate the requirements for a 
concrete foundation.

I have the Wind load calculator from OK1DFC and even though my dish is a 
mesh dish I will calculate for a solid dish. I have seen Jet Propulsion Lab 
data that from memory suggests that above 50mph or 80km/h the turbulence 
around the mesh looks similar to a solid dish. I cannot find the article but
I do remember seeing it! So I will calculate for a solid dish.

At 160km/h the on axis wind load is 33.3kN

If I understand correctly force on the mount is in N/m? So the mount is 3.5m
tall so the torque is 116.6kN/m - then I get stuck because I do not know how
to translate this into the forces on the foundation.

Can anyone help?

Pointers to papers to read perhaps?

73

Conrad PA5Y
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