Epic Rocket Acceleration during the cluster burn, flight computer log

The curve above is from the onboard HCX flight computer logging 500 samples/second.

You can see how the thrust curves of the four motors add up from the thrust curves below. F=mA, so they follow each other pretty closely since the mass loss of the burn is small compared to the rest of rocket.

The central long-burn motor lasted a full nine seconds, but with insufficient thrust to overcome gravity and drag.