question about Mercury and attitude

[ppakur]

Hi, I tried to mess up with gyros on purpose to see if Mercury pod will lose orientation once in orbit. I've set MANEUVER to OFF, which should disable gyros according to manual, used gyro cage, then done some major attiute changes. after flipping MANEUVER back to ON and GYRO to NORM, the pod perfectly realigned itself.

And my question is how exactly is that possible? I understand it should be able to roll in a way that puts the earth below me and then pitch downwards ~35 degrees below the horizon thanks to radiation sensors, but how can it orient itself relative to retrograde, when all the relevant info should be trashed after my previous actions? What is the yaw input here?

Am I missing something or the game is programmed to always put the capsule at the correct attitude when ASCS is set NORM and GYRO NORM, assuming no malfunction of these systems?

[N Quarter]

From my understanding ;

Turning the MANEUVER to the OFF position simply disconnects the ASCS reading from the Gyro, and the Gyro to the NORM position will connect the Gyro to the pre-programmed coordinates for RETROGRADE or RE-ENTRY, as the Systems are still 100% operational.

I will generally CAGE my Gyro's, disorientate myself, then put the Gyro's in FREE to Manually realign to Retrograde using the Window and Periscope. Once I'm happy with what I see, I'll change ASCS back to NORM and see how accurate I was.

Again, I haven't really read much into this, but that's just my general assumption as the Systems are still operational.

[LyraCreative]

Originally posted by ppakur:

Hi, I tried to mess up with gyros on purpose to see if Mercury pod will lose orientation once in orbit. I've set MANEUVER to OFF, which should disable gyros according to manual, used gyro cage, then done some major attiute changes. after flipping MANEUVER back to ON and GYRO to NORM, the pod perfectly realigned itself.

And my question is how exactly is that possible? I understand it should be able to roll in a way that puts the earth below me and then pitch downwards ~35 degrees below the horizon thanks to radiation sensors, but how can it orient itself relative to retrograde, when all the relevant info should be trashed after my previous actions? What is the yaw input here?

Am I missing something or the game is programmed to always put the capsule at the correct attitude when ASCS is set NORM and GYRO NORM, assuming no malfunction of these systems?

Hi!
This is the first craft player encounter. The Horizon Scanners, when enabled, detects the Earths horizon in pitch and roll, leaving the last vector a cross product. I then align the gyros automatically using these vectors. However, if you set the gyros to cage, they will lock to 0,0,0, and when you place them in free, they will drift relative to the attitude you had when caged. You can use this to define your own inertial platform.

This is a good video if anyone is interested:
https://www.youtube.com/watch?v=UXzhrhzGU9c

[ppakur]

Hello, yes, I'm aware of that. My only question was how the automatic system knows where retrograde is. Assume I'm on near-equatorial orbit, going from west to the east. horizon sensors allow the craft to slave the gyros relative to horison and keep this attitude. But how spacecraft knows which way is retrograde (west in this example). after all it could be horison stabilised but face any other direction (like north or south) and data from horison sensors would be the same.

If there's malfunction or I play with manual modes and I want to correct my yaw drift, I have to use window or persicope and allign my craft to make sure the heat shield faces prograde. I wondered what is the equivalent when spacecraft does it automatically. It's mostly curiosity, I really enjoy the game btw

[LyraCreative]

Thanks, that is great to hear! The default attitude of the craft is a retrograde/LVLH attitude that changes as the craft orbits the Earth. This will keep the craft into a fixed retrograde direction (depending on the attitude switch ofc). This means that the system knows that the platform is in LVLH, which means that the programmer can command a pitch relative to LVLH. This will ofc. be wrong if the gyros or the horizon scanners fails for various reasons. If this happens you can, as you mention, revert to using the mech onboard such as the periscope or window marks to align with retrograde.