Bixler2 VTO

[Maxy]

I am in the process of making the parts to convert a Bixler2 into a VTO & Landing model. There is a good example of this on u-tube, where the pilot has good control over the model, the video was taken at NASA in the States. The only information I have is taken from the video which is handy but not very accurate. At the moment I have made the two horizontal beams which hold the fore & aft motors 9" from the centre line of the fuselage the motors are 18" apart with CofG in the middle. I have swivel brackets to house the motors which will be moved via a servo & linkages on each beam for lifting and forward flight. I have 4 E-Max CF 2812 1500kv motors fitted with 7" x 3.5" 3 Bladed props, matching a 30 amp ESC will be fitted for each motor, hopefully all giving the same thrust, a max of 20 ozs. My main concern is that during the lifting period there is no pitch control the elivator will be ineffective I will rely on equal thrust from each motor to maintain level position wind would move it about a bit but the pitch should stay the same as on the utube video the pilot transfers from lifting to normal flight with ease via a rotary switch on the TX. Club members have said to me pitch control or the lack of it could cause the model to tip over & suggest that I should treat it as a Quadcopter & fit all the necessary software, I know nothing about quadcopters apart from the fact that don't function like aeroplanes, it would appear to be an over complication my Bixler2 will behave like a normal aircraft after leaving the hover . I have also heard that small computers can be used to improve the handling of a VTO & Landing plane. Should I continue slowly with care with manual lift & tilt or could this be difficult, I have 40 years of flying models with the usual good & bad days. Has anyone had experience of quadcopter functions applied to a conventional aircraft set up, are there any small computers that may improve the handling, any advice would be appreciated.

Best Regards

R Max Morris

 

 

Edited By Maxy on 26/05/2014 19:25:28

[Chris Jones 7]

Hey Maxy,

You won't be able to do this without some form of flight controller. If you lift off vertically you will go straight into ground effect and will immediately need some correction which you won't be able to do without the correct control of individual throttle response of the motors.

I have done a little research into this and I think the easiest way to do it is to go through a KK2 flight controller. It can be flashed with a special software that allows transition from vertical to normal flight modes and back. I think that without a flight controller your project is doomed unless you find another way of controlling the model in vertical flight mode.

But, I wish you all the luck and will definitely be following your progress. If you have any questions about quads, give me a shout, Im not an expert but I have seven spread over three different flight controllers! (I'm an addict!)

Chris

[Maxy]

Hi Chris, What would be the result if I were take off as normal with vectored thrust in horizontal all 4 motor facing forwards with wheels fitted 2 main on a U/C with a tail wheel or skid to help directional stability on the take off run, then rotate as a normal aircraft. When at a suitable height I good graduate. To semi hover or full hover any probs I could glide down and land dead stick on the U/C. I do like the idea of a KK2 flight controller, but I can't quite understand what would happen when I want to swivel the motors horizontal for normal flight when I would need to use my ailerons / elivator servos. I don't understand what being flashed with special software really means, where would you get this software from and would it be able to transfer from quadcopter mode to normal aircraft mode and utilise the onboard servos for normal flight and linear throttle control .

Regards Max

[Chris Jones 7]

Hi,

In theory you should be able to take off and fly no problem with the motors in the horizontal position. It is when you transition to hover mode that the problems begin. If you have enough height then you may get it to the point where it stops but you will have no control. If the wind moves it or one of you motors or props is slightly more powerful than the others you are not going to be able to recover. If you are in the hover you will not glide.

Software for the KK2 board is available free on line, you need a cable to be able to "flash" or upload this to the board. The cables are available in Hobby King and are not expensive.

I believe that the software for the board allows for full transition from forward flight to the hover and back again but you would need to research it more. I suggest you spend a couple of weeks over on the VTOL section of RCGroups to figure it all out but for the sake of £30 for a KK board and cable I would not be attempting this project without it.