The excellent answers to What are these circular spots on these Ariane V SRB nozzles? tend to indicate that unlike the IV, the Ariane V simply rests on two flat surfaces under the SRBs at launch time, and does not have a lock down mechanism to hold it in place until proper ignition and full thrust can be confirmed.

Those answers contain a lot of information and are worth reading.

Assuming this is the case, what would happen if for some reason one of the SRBs did not ignite at all, or started burning with substantially lower power, say less than 50%, or the nozzle failed promptly? (like this one did at the end of a test)

Question: Would the rocket fail to leave the ground and just sit there and burn, or would the resulting torque tip it over? Or would the auto destruct mechanism blow it up on the pad?

Space Shuttle Almanac tweet Ariane V

above: from this Space Shuttle Almanac tweet linked here. below: cropped from Capcom Espace's ARIANE 5 linked here.

cropped from Capcom Espace's ARIANE 5

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    $\begingroup$ I suspect the only significant difference is that nobody dies. $\endgroup$ Aug 9, 2019 at 2:30
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    $\begingroup$ I really don't know. If one EAP fails to ignite, then either (A) tip over and explode, (B) sit there until one side of the pad melts, then tip over and explode, (C) get unzipped by the range safety system and explode. If one of the EAPs ignites but the nozzle fails promptly, I'd expect significantly asymmetrical thrust, so it goes up off the pad, immediately U-turns, (D) crashes and explodes or (E) gets range-safetied and explodes. I would be astonished if the pad could take the heat of an EAP firing for two minutes. $\endgroup$ Aug 9, 2019 at 2:39
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    $\begingroup$ The best source I can find about the launch table is also from Capcom Espace but it's unfortunately completely French. $\endgroup$
    – GittingGud
    Aug 9, 2019 at 5:38
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    $\begingroup$ This is something KSP can simulate with great accuracy. $\endgroup$
    – user721108
    Aug 13, 2019 at 9:37
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    $\begingroup$ @qqjkztd that's a really great idea! The physics engine would be a much better simulator than the back of an envelope covered in drawings of spherical cows. $\endgroup$
    – uhoh
    Aug 13, 2019 at 9:40


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