Head to head

Kosmos 11K63 vs Pegasus XL

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

Kosmos 11K63: 300 kg

Pegasus XL: 443 kg

Side by side

7 comparable figures

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

Metric	Kosmos 11K63	Pegasus XL
Flights flown	126	32
Success rate	93.7%	90.6%
Payload to LEO (kg)	300	443
Length (m)	31	17.6
Diameter (m)	1.6	1.27
Launch mass (t)	48	23
Stages	2	3

Kosmos 11K63

Flight record

93.7% success rate118 of 126 flown · 8 failed

1965peak 1970 · 20 flights1977

Maiden flight 1966-05-24. Retired.

Pegasus XL

Flight record

90.6% success rate29 of 32 flown · 3 failed

1994peak 1996 · 4 flights2026

Maiden flight 1994-06-27. Still flying.

Kosmos 11K63 is built by Strategic Rocket Forces of Russia.Pegasus XL is built by Orbital Sciences Corporation of the United States (company profile on Space Index).

Full specifications and the complete launch history for each: Kosmos 11K63 · Pegasus XL.

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