# A few questions about VTOL Quadrotor X Tailsitter

**URL:** <https://discuss.px4.io/t/a-few-questions-about-vtol-quadrotor-x-tailsitter/3907>\
**Category:** Uncategorized\
**Created:** [July 15, 2017, 1:21pm UTC](https://discuss.px4.io/t/a-few-questions-about-vtol-quadrotor-x-tailsitter/3907 "2017-07-15T13:21:53Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![SiNianY](https://discuss.px4.io/letter_avatar_proxy/v4/letter/s/dec6dc/32.png) [@SiNianY](https://discuss.px4.io/u/SiNianY)\
**Post date:** [July 15, 2017, 1:21pm UTC](https://discuss.px4.io/t/a-few-questions-about-vtol-quadrotor-x-tailsitter/3907/1 "2017-07-15T13:21:53Z")

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Hi everyone,  
Recently I tried the VTOL Quadrotor X Tailsitter, however I have some questions about this kind of airframe.  
1, For some reasons, I can’t use four same motors, and the motor 1 is same as the motor 3, the motor 2 is same as the motor 4. So can I finish the transition from MC to FW ?  
2, I didn’t use the airspeed sensor. And I set the airspeed mode (FW\_ARSP\_MODE) to ‘declare airspeed invalid’ in the parameter of QGC. Should I use the airspeed sensor? Or I can use the ground speed to replace the airspeed ?  
3, When I try to get the transition from MC to FW, what should I do first, toggle transition switch? Or I make my aircraft pitch for a certain angle?  
4, How can I make sure that my aircraft have finished the transition when I get the data analysis from LogMuncher or Flight Review or when I test the aircraft?  
I know I haver asked many questions, but thank you very much.

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**Author:** ![dagar](https://discuss.px4.io/user_avatar/discuss.px4.io/dagar/32/22_2.png) [@dagar](https://discuss.px4.io/u/dagar)\
**Post date:** [July 15, 2017, 6:55pm UTC](https://discuss.px4.io/t/a-few-questions-about-vtol-quadrotor-x-tailsitter/3907/2 "2017-07-15T18:55:33Z")

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Which config did you select? Can you post a log?

1. This is probably a configuration issue, but I need to know more about your setup.
2. Tailsitter transition currently depends on airspeed, although this could be changed.
3. Just keep it level, flip the switch and the controller will do the rest.
4. Make sure you’re using the new logger (SYS\_LOGGER 1) and upload logs here - [http://logs.px4.io/](http://logs.px4.io/). A VTOL log will have an additional plot showing the VTOL states.

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**Author:** ![SiNianY](https://discuss.px4.io/letter_avatar_proxy/v4/letter/s/dec6dc/32.png) [@SiNianY](https://discuss.px4.io/u/SiNianY)\
**Post date:** [July 17, 2017, 2:00am UTC](https://discuss.px4.io/t/a-few-questions-about-vtol-quadrotor-x-tailsitter/3907/3 "2017-07-17T02:00:49Z")

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Thank you very much. I used the traditional log analysis in the LogMuncher. Should I try the new Firmware?

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**Author:** ![dagar](https://discuss.px4.io/user_avatar/discuss.px4.io/dagar/32/22_2.png) [@dagar](https://discuss.px4.io/u/dagar)\
**Post date:** [July 17, 2017, 2:13am UTC](https://discuss.px4.io/t/a-few-questions-about-vtol-quadrotor-x-tailsitter/3907/4 "2017-07-17T02:13:35Z")

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Yes in general I would always use the latest stable PX4 and QGroundControl, however there aren’t specifically any tailsitter changes.