Transverse Rotor UAV: Bell-Hiller CONCEPT

I have been moving forward with my project to build a transverse rotor UAV. Here is a quick overview of this Bell-Hiller concept. (Oh, btw this is only a quick sketch done in Google Sketchup, it isn't totally to scale nor have I drawn in the entire structure)

1) Single brushless motor will drive conter-rotating rotors
2) CCPM swash plate will provide additional level of control including roll-control w/o gyroscopic affects.
3) I am using a Bell-Hiller mixing instead of mounting rotors directly to motors (no swash or flybar) and using large servos to control pitch and roll. This will allow for added inherent stability, and I will be able to use much smaller servos

Next step is to verify this design with the community (you), decide how much I can buy off the shelf vs how much I need to build myself, and then start building and working on the electronics portion. As soon as I know how many servos/sensors I'll need, I'll choose a microcontroller and start that parallel project. Stay tuned, I've told too many people about this project to give up now... :-)

the body is 7" wide and so overall ~10in, however I'm still trying to further scale it down. I'm trying to get this to 8 x 8 x 2.5in total .

I'm using flybars because I fear that as I shrink this platform, it will require very sensitive servos and high i/o bandwidth sensors to stay autonomously stable. I have a blade msr and I was thinking of maybe modifying a set of msr rotor heads to ccpm.

Add a basic 3axis accelerometer under each prop, a digital compass and gyroscope for stabilization, and many long nights programming, and I think I can make this a rather stable sub micro VTOL. I'm not sure I want to rely on sensors for the whole route.

thanks for the advice guys, I agree this is a major project! I hope to do it right the first time...so keep your comments coming I appreciate it. I'll be sure to share the progress I make.

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Comments

jaron February 8, 2010 at 12:31pm

This is not exactly what you want but basically the same: Twinn Rexx

Tech Model Products Twinn_Rexx Tandem Helicopter Page
Developer

Mark Colwell February 8, 2010 at 8:13am

With collective pitch helicopters, I found that smaller was twitchy, no hands-off hover, but with larger choppers the inertia helps to stabilize chopper allowing 5-10 second of hands free hovering. 500 plastic Clones are $68 Also micro choppers are harder to work on, more susceptible to crash damage.
Jeff February 8, 2010 at 7:02am

the t rex 500 is nearly 35" in length. I'm shooting for 8". Am I going in the completely wrong direction, thinking that I can reap the benefits of inherent stability for such a small platform?
Knuckles904 February 8, 2010 at 12:21am

As cheap as they come, $37 for full trex 450 clone:
Developer

Mark Colwell February 7, 2010 at 10:18pm

Think about a T-rex 500 size platform, It would be more stable and easily carry your multiple cpus sensors and video, good parts are available etc..
Jeff February 7, 2010 at 9:50pm

the body is 7" wide and so overall ~10in, however I'm still trying to further scale it down. I'm trying to get this to 8 x 8 x 2.5in total .

I'm using flybars because I fear that as I shrink this platform, it will require very sensitive servos and high i/o bandwidth sensors to stay autonomously stable. I have a blade msr and I was thinking of maybe modifying a set of msr rotor heads to ccpm.

Add a basic 3axis accelerometer under each prop, a digital compass and gyroscope for stabilization, and many long nights programming, and I think I can make this a rather stable sub micro VTOL. I'm not sure I want to rely on sensors for the whole route.

thanks for the advice guys, I agree this is a major project! I hope to do it right the first time...so keep your comments coming I appreciate it. I'll be sure to share the progress I make.
Jack Crossfire February 7, 2010 at 3:42pm

The T-Rex 450 rotor head is what most people use for this. It was under $200 last year & can be converted to flybarless. Since modern gyros are free, most people don't bother with bell hiller mixing anymore.
Mike February 7, 2010 at 12:47pm

There are a variety of Chinook type RC models of helis around now. Some with co-axial rotors and others with single rotors, albeit a lot more expensive. I would suggest taking a look at these and there might be an easy candidate to hack into. The stabilisation is going to be one of your biggest challenges and experimenting with helis is not at all cheap - it takes a lot of passion and cash - it is as destructive as a mistress! I would suggest that working on the electronics and coding be way up front and use a hacked RTF heli to use as a cheap test bed.

My two Kwanzas...
Zane the brain February 7, 2010 at 12:37pm

you could probably just salvage old parts from r/c helicopters
Knuckles904 February 7, 2010 at 12:36pm

any idea what size/scale? the size you pick for the rotor heads will make a lot of difference in the overall price. I would recommend using 450 size (t-rex) knockoffs as theyre about as cheap as you can find anywhere and very good quality nonetheless.

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