Head to head

Atlas V 551 vs Vulcan VC6L

Two vehicles in the same payload class. Every figure below comes from the same two sources for both rockets, and a row appears only when both publish the input.

Payload to low Earth orbit

Relative

Atlas V 551: 18,850 kg

Vulcan VC6L: 27,200 kg

Side by side

8 comparable figures

The highlighted value wins the row. Rows where neither direction is better, like length or stage count, highlight nothing.

Metric	Atlas V 551	Vulcan VC6L
Flights flown	23	0
Payload to LEO (kg)	18,850	27,200
Payload to GTO (kg)	8,890	15,300
Liftoff thrust (kN)	12,269	18,110
Length (m)	59.7	67.4
Diameter (m)	3.8	5.4
Launch mass (t)	573	877
Stages	2	2

Atlas V 551

Flight record

100% success rate23 of 23 flown

2006peak 2025 · 5 flights2026

Maiden flight 2006-01-19. Retired.

Vulcan VC6L

Flight record

Maiden flight not recorded. Still flying.

Atlas V 551 is built by United Launch Alliance of the United States (company profile on Space Index).Vulcan VC6L is built by United Launch Alliance of the United States (company profile on Space Index).

Full specifications and the complete launch history for each: Atlas V 551 · Vulcan VC6L.

Specifications from Launch Library 2 by The Space Devs, launch records from Space Index. Derived figures are computed here; see sources and method.