Falcon 9 First Stage and Second Stage Block differences

UPDATED Jan 4, 2018

This post covers the external differences of Blocks 1 through 4 of the Falcon 9 rocket.
For the novice reader, SpaceX Falcon 9 has 2 stages: First Stage and Second Stage (Upper Stage). These stages have gone through several modifications through the years. At the time of this post, Block 5 First Stage is still yet to be flown.

The Block 1 First Stage was flown on the original Falcon 9 1.0 configuration. This rocket was completely different. The engine section had 9 Merlin engines in a 3 x 3 pattern configuration.
The first Demo Flight of a Falcon 9 v1.0 flew on June 4, 2010. It didn’t have landing legs at the time. It will not be discussed here.

As a paper model designer, my work is based on photos of the launch vehicles, diagrams and all sorts of references available online. I always look for external details that have changed through the years, mission by mission. As this is the case, I have compiled all my findings into a spreadsheet for my personal use, showing all the external changes on the Falcon 9 First stage and Second stage. At the beginning it became a puzzle, but as more information was added, the external differences became obvious.

The following information has been corrected thanks to Reddit SpaceX forum.

Block 2 First Stage V1.1

Block 2 debuted on Sep 29, 2013 with the CASSIOPE mission. The Falcon 9 was a v1.1 configuration and had 9 Merlin engines in a circular configuration this time. The front view of the first stage shows a long fuel line that crosses the entire length of the stage and has no other features. On the back, the umbilical side that faces the strongback, shows a thicker line with one feature on the lower section close to the legs that bulges from the main line. I have not been able to know the name of this feature but is visible on photos.

Falcon 9 v1.1 Jason 3 mission was the last Block 2.

Block 1 First Stage V1.2

The Block 1 started with the maiden flight of a Falcon 9 v1.2 or also known as “Full Thrust” on Dec 22, 2015 with the launch of OrbComm Og2 mission 2. Apparently the external features are similar to Block 2 V1.2

Block 2 First Stage V1.2

Block 2 shows more features if compared to the previous one. On the front, the fuel line had 2 thin rectangular features not shown before. One is in the leg area and the other one is placed halfway the first stage. On the back, It shows two bulging sections on the main line. Falcon CRS-8 became the first Block 2 V1.2

Block 3 First Stage V1.2

Falcon 9 Amos-6 was the first mission of a Block 3 but it was destroyed at the launch pad.

On Jan 4, 2017, the Falcon 9 v1.2 Iridium NEXT 1-10 mission was the first successful Block 3 that was launched. This time the Block 3 had only one thin rectangular feature on the front of the first stage. The back of the rocket showed no changes.

This configuration has been consistent throughout all the subsequent Block 3 missions.
At the time of this post, the Falcon 9 v1.2 EchoStar-105/SES-11 was the last reflown Block 3 mission.

Second Stage comparisons

Differences between versions 1.1 and 1.2 are mainly the size of both the Interstage and Second Stage sections.

The Second Stage Block 2 was the version 1.1
Second Stage Block 3 debuted on the maiden flight of the Falcon 9 Full Thrust or version 1.2

Block 3 Second Stage

Second Stage Block 4 debuted with the Falcon 9 v1.2 NROL-76. This mission used a Block 3 First Stage.

Block 4 Second Stage

Block 4 First Stage V1.2

Block 4 debuted on the Falcon 9 CRS-12 mission on Aug 14, 2017 from KSC Pad 39A. This modification shows only one thin rectangular feature at the top of the first stage. The back of the rocket remains the same with no changes.

In regards to my Falcon 9 paper models for the v1.1 configuration, the files have not been updated with these findings, yet. Some of the files corresponding to Block 3 have not been updated, either.
Files will remain the same until further notice. My work is not considered to be complete. There are some Falcon 9 missions that lack photos of the rocket from other angles that could have helped to fill in the gaps that I still have in my work.

UPDATE: Dec 22, 2017

After posting this on Reddit at subreddits SpaceX and SpaceX Lounge, not surprisingly, I received an overwhelming positive response. It was so gratifying reading the comments and at the same time learning new information I never knew. I guess, we all were wrong about the Falcon 9 Block classification.
So, here is the truth coming from members at Reddit SpaceX and from SpaceX employees:

Falcon 9 v1.0

• Block 1

Falcon 9 v1.1

• Block 1
• Block 2

Falcon 9 v1.2

• Block 1
• Block 2
• Block 3
• Block 4
• Block 5

Thank you all!

Check my Falcon 9 paper models for ALL missions up to date, here.
Please, send you comments.