How many power expander are allowed per robot?
Since I do not have posting privileges in the Q&A, I’ll post in this thread. You are allowed one power expander. See rule <R13b>:
Make sure to look in the manual before you post on the Vex Forum, and especially before you post in the Q&A channel, which only VEX Staff can respond in
We ask you to please thoroughly read the VEX Robotics Comeptition Starstruck Game Manual and to please review the Q&A Usage Guidelines before posting in this forum. Specifically, please quote the rule or definition that your question is referring to.
Let’s take a look at <R13b> from the VEX Robotics Comeptition Starstruck Game Manual. I’ve bolded some text for emphasis:
Thus you can only use one power expander.
Did I do good? I think that’s pretty close 
It’s only good if Karthik says it.
Maybe he w2as hoping for a rules change. Given some of the answers given by Karthik this year, who knows what his answer would be. I know of at least one rule he simply made up that had nothing to do with what was written in the rules and there are other answers he has given that simply do not make sense. Trying to anticipate answers from Karthik has been like shooting blind this year.
Can you clarify what you mean?
I think this person may or may not be referring to <SG6a>
I think Tabor is asking what Elohssa was implying, and best left to the poster to clarify.
Here is one example:
https://vexforum.com/t/taken-to-school-by-acme-robots/17986/1
Based on R1 Karthik stated “Once a Robot (defined as Subsystems 1 and 2) is entered in an event under a given team ID#, the Robot may not compete under any other team ID# at any subsequent event.”
Here is R1 and it simply does not say what Karthik says it says.
<R1> Only one (1) robot will be allowed to compete per team in the VEX Robotics Competition. Though it is expected that teams will make changes to their robot at the competition, a team is limited to only one (1) robot. As such, a VEX robot, for the purposes of the VEX Robotics Competition, has the following subsystems:
Subsystem 1: Mobile robotic base including wheels, tracks, legs, or any other mechanism that allows the robot to navigate the majority of the flat playing field surface. For a stationary robot, the robotic base without wheels would be considered Subsystem 1. Subsystem 2: Power and control system that includes a VEX legal battery, a VEX control system, and associated motors for the mobile robotic base. Subsystem 3: Additional mechanisms (and associated motors) that allow manipulation of game objects or navigation of field obstacles.
Given the above definitions, a minimum robot for use in any VEX Robotics Competition event (including skills challenges) must consist of 1 and 2 above. Thus if you are swapping out an entire subsystem of either item 1 or 2, you have now created a second robot and are no longer legal.
a. Teams may not compete with one robot, while a second is being modified or assembled. b. Teams may not switch back and forth between multiple robots during a competition.
Nothing in this rule can be seen as a restriction of one team using a robot in an event and another team at another event using the same robot. This is something that was completely made up by Karthik, but since he has stated it on the official Q & A it is now a rule.
There are other examples like SG6a where some of his statements were contradictory.
He is the man, so what he says goes no matter how poorly he is interpreting what is written or adding to what is written in the game manual.
“Nothing in this rule can be seen as a restriction of one team using a robot in an event and another team at another event using the same robot. This is something that was completely made up by Karthik, but since he has stated it on the official Q & A it is now a rule.”
I don’t believe that it “was completely made up by Karthik”. The intent of the rule is to allow a team to attend a competition with one robot (determined by subsystems 1 and 2) that can have multiples of subsystem 3 (each variation must pass inspection). This has been done rather infrequently, but has happened. However, it is NOT the intent of the VEX Robotics Competition to allow one team to compete at an event with a particular robot then at the next event have a related team compete with the same robot used by the first team. This is to prevent the building of a super robot by a group then using it to qualify each of the teams in that group for their respective state/regional competition based on the that single robot and not on the merits of the robots that each individual team designs and builds. I personally have a real ethical problem with a group that would choose to try doing that.
You may have your opinion of Karthik’s rulings. However, since neither you nor I are on the Game Design Committee, I think it is very difficult to state that he is interpreting the Game Manual poorly. SG6a is a very difficult rule to interpret and, yes, maybe it could have been worded more clearly. The VEX community is VERY good at finding all kinds of loopholes in virtually all of the rules.