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Launcher Load Factor

Launcher Load Factor

Launcher Load Factor

Hi, may I ask the load factors given in the launcher user manual are used for static analysis only?

Say, axial 5G,lateral 9G and we run the static acceleration.

What about vibration analysis? Are we also take these 5G as a multiplier in vibration axial direction?


RE: Launcher Load Factor

there should be a vibration spec.

"5G" ... is limit, but static design to ultimate ?

another day in paradise, or is paradise one day closer ?

RE: Launcher Load Factor

Hi rb1957, there is vib profile. Some of colleagues talking to use the 5G as multiplier to multiply with the G force given for vibration profile as the axial 5G is given under design load factor which might confuse them?

RE: Launcher Load Factor

oh boy !

no, I would definitely not multiply their vibration loads spec by their static load factor.

another day in paradise, or is paradise one day closer ?

RE: Launcher Load Factor

Concur with rb.

RE: Launcher Load Factor

Thanks everyone!

Another concern is if combined load factors shall be considered? Either to apply the G force in three axis at the same load step or calculating the combined margin based on the result from each axis load condition?

RE: Launcher Load Factor

That's a mistake I often see. Typically the force in the 3 directions are uncorrelated in the time domain, hence you should test with 1, 0 and -1 scaling in each direction, which in a linear system gives you 13 tests
x y z
1 1 1
1 1 0
1 1 -1
1 0 1
1 0 0
1 0 -1
1 -1 1
1 -1 0
1 -1 -1
0 1 1
0 1 0
0 1 -1
0 0 1


Greg Locock

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RE: Launcher Load Factor

Hi Greg Locock,

Thanks for your sharing. Is the below what you are pointing?

RE: Launcher Load Factor

sorry , but is it ?

particularly if az is between 1.8 and 3.2 ?

but if you number unit cases in each direction, wouldn't you run 5 unit cases (assuming X only +ve), then factor these together ...
case1 is 1 m/s +X
case2 is 1 m/s +Y
case3 is 1 m/s +Z

then 2.5 m/s X 0.3 m/s in Y and Z is 2.5*case1 + 0.3*case2 + 0.3*case3 ?

unless that's what people meant, or unless I'm wrong (again) ...

I can see that you may want to run the full gamut of cases (+veY and +veZ, +veY and -veZ, -veY and +ve Z, -ve Y and -ve Z, +veY only, +veZ only, -ve Y only, -ve Z only)
and combine these unit results to achieve what you want.

is +veY only = (+ve Y and +ve Z) + (-ve Z only) ?

another day in paradise, or is paradise one day closer ?

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