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Jul 11, 2016, 01:58 PM
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Vector modes on Fixed Wing: 3DH vs Gyro?


I've read the manual, but it isn't clear to me what the difference between 3DH (3D with Heading Hold) and GYR (Gyro Stabilize) modes are on a fixed wing (flying wind with just two elevons)

Overall, I want to start out with three modes:
- Nothing. Vector does as little as possible to the model. I'm using "OFF" for this, is this the right thing?

- Stabilized, but lets me go in whatever orientation I want. I'd like the Vector to resist a wind, turbulence at least a bit. I'm looking for a "locked in" feel. I'm currently using 3DH for this, is that right?

- Return to home. This is also my failsafe setting. Not much to say here, using RTH.
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Jul 18, 2016, 01:28 AM
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WEREE's Avatar
3DH is like GYR except that 3DH tries to add in heading hold nose heading. The pitch and roll axes will be in rate mode as usual. Even if you have a rudder, the Vector doesn't control the rudder in fixed wing mode so the Vector will try to roll the plane left and right for a heading hold effect.

I use GYR for my fixed wing "acrobatics mode" and have a three position switch to control gain. GYR is also needed for take off and landing -- don't use any 2D mode for takeoff/landing. One of my Vector equipped planes is an EDF jet that is in GYR mode most of the time. This jet's crisp locked in feel in all attitudes is so very satisfying!

Yes, you can use "OFF" to disable all gyro stabilization on a fixed wing setup. However, due to having just a 3 position switch for autopilot mode selection, I would just use GYR and use another three position switch for gain control where the lowest setting of gain will effectively disable gyro. However, a side note, I kinda don't wanna fly planes without some sort of gyro stabilization now. Indeed, I now have the cheap but effective OpenPilot/LibrePilot CC3D for most of my regular non-FPV planes. At just $14 a pop and a few grams of weight, its a no brainer. The Vector's gyro performance on my EDF jet has influenced so much that I pretty much have some gyros on fixed wing non-FPV planes! It makes any plane have a "bigger plane feel" without the weight.

On the subject of gain, I usually leave the gain fairly high as the Vector appears very fluid with its rate mode response. It provides crisp stabilization but stays out of your way when you want to do acrobatics. Of course, the amount of gain that is proper will depend on your craft, control surface sizing and servo types. I've been considering 3DH and it would likely work as well for my fixed wing flying. I also added in a Vector alert that shows on my OSD a message like, "WARNING: LOW GAIN" if my gain is on the lowest setting. There is a rare time I would even put in low gain such as in early build testing. All other times, I consider the low gain setting to be an improper state so hence the automated warning.

The second autopilot mode I have is 2DH which hold altitude and heading hold. Its like your car's "cruise control" but for aircraft. 2DH is very very good for long range flight where you just want to set a direction and let the plane go straight. The Vector's altitude is very very good all of the time and holds altitude better than I could do. Its exemplary for alleviating that part of pilot fatigue for a long range flight. Without altitude hold, I'm sure my flights would have "up and downs" in them as you know altitude is touchy to control perfectly especially on a long range flight where your focus will wander. However, I'm finding the 2DH heading hold is not so good compared to its altitude hold. The 2DH heading hold doesn't work as you would expect. Still, 2DH is what want to use long range flying. 2DH doesn't allow you to go inverted.

My third mode is the "RTH test" which I usually activate at least once per flight to test that RTH is actually working before heading out for a long range flight. You also want to train yourself to go into this mode if your radio link fades out at long range where your craft is at the edge of its control range. If not, the Vector may oscillate between RTH and another mode as your radio link fades in and out. This can be dangerous and cause the plane to go erratic. Even in RTH mode, you still have control of the plane when your control sticks are not centered. You can override RTH control at will with stick inputs but I would just let it go until the plane recovers on a course for home. Only then tap the controls around a bit to ensure your RC link is fully established before exiting RTH mode to continue your flight.
Last edited by WEREE; Jul 18, 2016 at 01:29 AM. Reason: Typo


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