# Homework Help: Moment of Inertia for connected, hinged panels

Tags:
1. Sep 17, 2016

### snpierce

1. The problem statement, all variables and given/known data

There is a solar panel array of 3 panels connected to a spacecraft. The panels in the array are connected linearly (in a row: panel1 + panel2 + panel3 + spacecraft) with hinges. They are all 0.2 meters by 0.3 meters and connected along the 0.3 meter side using 2 hinges for each panel. I'm looking for the MOI so that I can calculate the angular momentum of all 3 panels when they are released from their folded position once the craft is in orbit. They are folded together on the hinged sides and all 3 are in a "pile" before being released.

2. Relevant equations
I=1/3*M*a^2 'a' being the length of the shorter side in this case 0.2

3. The attempt at a solution

Innermost panel has to swing outward with the mass of the other 2 attached to it: I=1/3*(M*3)*a^2
Middle panel has to swing outward with the mass of itself plus outer panel attached to it:
I = 1/3*(M*2)*a^2
outermost panel: I = 1/3*M*a^2

Since the panels are connected and moving simultaneously when released, I'm not sure this is the way to do this and I can't find any similar examples which makes me think I'm really missing something.
Any help would be greatly appreciated!

2. Sep 18, 2016

### CWatters

I doubt I will be able to help but I think sketch might help. Are the panel's "rolled" or "consterina" pattern?

3. Sep 18, 2016

### Nidum

Answer you are looking for depends on how the motion of the panels is being controlled . You really need to know how the deployment mechanism works .

4. Sep 18, 2016

### snpierce

Concertina pattern.

5. Sep 18, 2016

### snpierce

The panels will be released all at once - a chord holding them "pinned down" in their folded position will break and the entire solar panel array comes free at once.

6. Sep 18, 2016