Four Rotor Helicopter

[Pekkle_Juice]

Hello,

I have recently viewed a video of the Draganflyer four rotor helicopter and was quite fascinated by it. Looking at the specs for it, I noticed that it has a limited flight time as well as limited payload capacity. I asked a local rc dealer about a gas powered version of a four rotor aircraft and I was told that the method used to stabilize the Draganflyer would not work on a gas powered version and thereby one does not exist. I've searched the internet and have not been able to find one as of yet. Is it true that stabilizing a four rotor gas helicopter is too complex and not pratical to build? I would like to attempt to build one and would appreciate any input regarding stabilization or resources that would help me in that area. Thanks in advance.

Pekkle_Juice

[skyhawk]

Thats BS! There are a few companies that have 3 - 4 - and evn 5 bladed heads available. Of course they aren't that cheap.

Check out the link, if you scroll down more they have multi bladed tail rotors too.:

http://www.centuryheli.com/products/rotorheads/index.html

[skyhawk]

You can search hirobos site - they have many muliti bladed scale models (even the twin rotor vertol with 2 - 3 bladed heads:

http://model2.hirobo.co.jp/english/

And of course the ultimate is vario, just look under scale helis:

http://www.variousa.com/index.html

[Dave Robelen]

Hi,
It sounds like we have a bit of "apples and oranges" going here. The DraganFly is a four seperate rotor helicopter, and depends on precise speed control (and mixing of the same ) for stability. Multi blade heads are a different matter, they are still on one shaft. Even the two rotor Sikorsky normally has the two rotors coupled mechanically for stable operation. Electric motors provide the fine degree of speed control needed for the unique setup of the DraganFly.
Regards, Dave

[JSG]

I'm very interested in increasing flight times and lift capacity of 4 rotor helicopters. I have a Draganfly IV and find it to be a great camera platform. The problem is, without a teather, flight times are too short. The Draganflyer is also too small to carry any real payload. Draganflyer has another 4 rotor heli out that can lift 1 pound called the XPRO.

I too am looking for gas powered solutions such as heli engines or ducted fans. The problem is changing RPMs fast enough to keep the heli stable. I haven't found the answers yet, but I'll keep looking. Have you had any luck or ideas? It may be possible to use 4 independant rotors that change pitch, like a helicopter, along with gyros? But of course that doesn't account for YAW control. I guess for now were stuck with electric motors.

Best Regards

[rminnett]

I'm an undergrad Electrical and Computer Engineering student working on my senior design - a electric 4 rotor AUV with an accelerometer/gyro stabilization system. Response time on a gas powered motor could be an issue, but would probably give a higher thrust/weight ratio and allow a larger payload. As for yaw control, this is done by having the rotors spin in pairs - for example, left and right counter clockwise, front and back clockwise. If you speed up the left and right and slow down the front and back, the overall thrust can remain constant, but the torque would produce counter clockwise yaw rotation.

Let me know if you have other questions and/or want to collaborate on building an autonomous 4 rotor gas helicopter in the future.

Rupert

[JSG]

Thanks for that great information. I'm currently working on a couple of raptor helis and won't have time for a while to explore the 4 rotor project.

Thanks again.

[MikeWz]

Just an idea, but rather than worrying about speeding up/slowing down the motors to control the heli (other than up and down) why not have the blades pitch? Adding/lowing the pitch of the blades can produce a similar effect. It would be like rasining the head speed on one of the blades to get the helicopter to pitch. Just a suggestion.