Im trying a vizzy script for an SSTO for which the chip is set to rocket (it had stability issues reaching orbit set to plane pre-vizzy script). The craft still needs constant roll input to maintain wings level but I can't get my script to do this.

What vizzy script can I use to have the cratft be able to maintain Wings-level attitude so it doesnt drift left or right during flight?

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    11.3k KraZIvan

    @sflanker No worries and thanks! I'm studying your vizzy script and the explanations you typed within the script are very helpful. Admittedly my craft is quite heavy at full capacity and although it has fairly good lateral stability and I have worked out some of the roll problem at lower altitudes for the most part, the roll issues seem to come back at higher altitudes. I think the autopilot has a hard time controlling the craft out of atmo as a plane, and inside atmo if it has a rocket orientation. I'll keep at it though!

    1.5 years ago
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    Mod sflanker

    @KraZIvan oops, sorry I failed at completely reading your post. I hope my Vizzy script is useful let me know if you have any questions. However it does seem like given the rocket auto pilot's default behavior it should be able to maintain stable roll. There must be something about your craft inducing the roll in the first place.

    +1 1.5 years ago
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    11.3k KraZIvan

    @AnotherFireFox The idea for a PID Controller sounds intriguing, however as you said it would be more difficult to implement. I am already using the "set roll to" block, I have used it as a stand-along block and also inside a "while" block, I think I will try to repeat this block and see if that changes anything.

    @sflanker as I already mentioned, the craft is set to rocket orientation. Adding dihedral is a good idea but I have already implemented this, my problem is that since this is my first attempt at a vizzy program, I don't fully know and understand how to use the blocks correctly, so I'm more looking for pointers in this regard. I am able to control the craft manually and maintain a wings-level attitude throughout the flight, I just can't translate this to vizzy at the moment. Thank you for sharing your craft though, it sounds as it might very well have the solution I'm looking for, since pitch will (for the most part) the only variable to change during my craft's flight. As far as why I didn't share my craft, there are many reasons, the main one being that I wanted the craft to be a surprise for the community and I hate to spoil it, plus the question is in regards to vizzy and not about the craft's aerodynamics.

    1.5 years ago
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    Mod sflanker

    As with many such questions, it would be a lot easier to diagnose problems and make suggestions if people would share their craft.

    1.5 years ago
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    Mod sflanker

    What altitude and pitch angle are you developing stability problems at? Are you using a rocket orientation craft or a plane orientation craft?

    At lower altitudes, stability problems can be addressed with proper aerodynamics. If you tilt your wings slightly upward then the craft will naturally tend toward level roll. However, as you increase altitude and pitch angle aerodynamics stop working for this purpose. In my SSTO experiments I've had limited roll stability issues later in the flight (altitudes over 20km and pitch angle over 45 degrees), but they were slight enough to safely ignore (I was still able to rely on the autopilot to achieve the desired pitch and heading).

    Also, are you using auto pilot to lock heading and pitch (either to explicit orientation or prograde)? If so, and if you are using rocket orientation, then you have some inherent stability or control issues with your craft design. The autopilot is designed to null out any roll rate. It could be that adjusting gyro power, or weight distribution, or autopilot settings solves your problem without resorting to Vizzy.

    In a significantly more trivial case I've been able to use Vizzy to set the Roll input based the current and desired orientation (I used the current pitch axis versus a desired pitch axis to determine the amount of change in role required), and the current angular velocity around the roll axis. However there are challenges if you are trying to do this and use autopilot. Here is an example craft with such a flight program.

    1.5 years ago
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    Good Solution: Jundroo adds the set roll to 'x' block
    Difficult Solution: Use PID controller to maintain desired roll

    +1 1.5 years ago

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