The chain duration for any chain is “first launch to last launch,” without exception. The prefire of the chain is the prefire of the first effect in the chain if it is a shell, and is an arbitrary offset into the effect otherwise.
|Type of item
|The value specified in the prefire column, if present, else in the VDL, as in “Chain of 5 Salute 0.0 PFT”, else the default lift time for a shell of this caliber if the first device is a shell, else zero; the lift time of the all effects being adjusted (if they are shells) to equal the specified prefire only if the prefire is non-zero
|First launch to last launch
|Expiration of the star or stars or emission of the last device — minus the prefire; or zero if that would be negative
To calculate the delays in between the devices of a chain with more than one device based the duration of the chain, simply divide by the number of shots minus one.
DeviceSeparation = ChainDuration / ( NumberOfDevices - 1 )
If a chain has a single device, its duration is zero, by definition, even if the value in its “Duration” column in the Effects window is something else.