MLAS of the Future

The illustrations above show what the MLAS shroud
will look like in the near future, more or less.

Obviously it was drawn when the number of motors
were to be as many as six, the version just flown
is designed to use only four motors. The folding grid
fins are shown though, and four is the number since
no matter what, one side is reserved for crew
access.  Once the MLAS gains it's grid fins, the boost
test vehicle will lose it's coast skirt and associated
upper finset. Depending on the  nature [flight
envelope] of the future tests, the test  booster will
mutate further still.   MLAS's current good looks are
probably a one shot deal.

Before a live MLAS shroud abort flight can take
place, the motor manifold connecting the four
shroud motors around the apex will have to be
ground tested. That'll be an event to look for in
future NASA news releases.

The Block I & II Ares LAS uses a single abort
motor that is mounted upside down, with the exhaust
flowing through a hot manifold to turn it around
approxx 135deg in order to exit the nozzles, this
constitues a large weight and performance penalty.
Scary hot too.
With the MLAS motor system there are multiple
motors which all must ignite. Of course, the motors
and ignition systems are very reliable, but just in
case, the motors will be interconnected with a
manifold at the top end. This allows exhaust gasses
from the other three to ignite the stubborn one.
Since gas cross flow will be minimal once all motors
are lit, the MLAS manifold will run a lot cooler and
can therefore be made a bit lighter than on the LAS.

BTW;  Rumor has it, Quest is fast tracking an 
MLAS modroc kit.