The Ars Technica articles

• From zero to 100mph in 1.2 seconds, the SuperDraco thruster delivers
• Dragon was destroyed just before the firing of its SuperDraco thrusters

both include this "file photo" Twetted by Elon Musk 2:27 PM - 18 Jun 2012:

Just fired our Superdraco escape rocket engine at full thrust! Needed to carry astronauts on Dragon

Why does the exhaust look so under-expanded? It looks like it doubles in diameter within a distance of only one diameter, and soon thereafter to a factor of 3 of it's exit diameter.

Doesn't that result in a substantial loss of thrust available to the spacecraft?

below: found in NASA Spaceflight Forum

The Ars Technica articles

• From zero to 100mph in 1.2 seconds, the SuperDraco thruster delivers
• Dragon was destroyed just before the firing of its SuperDraco thrusters

both include this "file photo" Tweeted by Elon Musk 2:27 PM - 18 Jun 2012:

Just fired our Superdraco escape rocket engine at full thrust! Needed to carry astronauts on Dragon

Why does the exhaust look so under-expanded? It looks like it doubles in diameter within a distance of only one diameter, and soon thereafter to a factor of 3 of it's exit diameter.

Doesn't that result in a substantial loss of thrust available to the spacecraft?

below: found in NASA Spaceflight Forum