POLL: Coaxial vers. CCPM Helicopters

The LINKAGE makes ME wonder

Don't spoil it, answer the POLL before you LOOK at the link ... or NOT

        --[ http://youtu.be/CcpUdxlgliA ]--

After watching the video it looks like the Russian coaxial helicopter also has collective pitch so the the poll may be somewhat skewed.

I voted toys and I'm sticking with it even after seeing the video. 

Well, I voted toys (since I thought we were talking about toys), but I need to change my vote As a fan of VTOL technology I like the coaxial concept. The systems are more efficient than the Siskorsky design, it take 30% of the engine power just to run the tail rotor which does nothing for you. Plus the increase in rpm applied to the reduced size of the tail rotor unit has always been a cause of failure. But the coaxial is much more difficult to design and implement. But they do work good when they work:

http://youtu.be/IHyVNdZfILE

My favorite though is the intermeshing rotor design like KMAX, the FL-282 was the first production helicopter in the world during the late 30's early 40's and still to this day it holds the record for the most efficient, highest lift capacity per power unit of any helicopter ever built.

As shown in the video it was also capable of short term hands off flying, just an incredible machine even to this day:

http://youtu.be/AOcNCO6S_vY?t=2m17s

http://en.wikipedia.org/wiki/Flettner_Fl_282

And just to keep it RC related, oh yeah, they make em.........

http://youtu.be/dmrnmTiw18E

Here are some heli's that the 30% power reduction aren't hurting much.  Enjoy 

I don't know how the first fella kept the blade tips out of the grass. 

http://www.flixxy.com/bo105-helicopter-aerobatics.htm

http://www.youtube.com/watch?v=ZkLwtCogci0&feature=related

http://www.youtube.com/watch?v=kTx_1TBuHlo&feature=related

http://www.youtube.com/watch?v=iAJ4CcLPDRY&feature=related

That first guy has got to be dead by now GPBill.

...Tiger

+1 Bill

Yeah, go RED Bull --->

[size=1.25em]Lynx helicopter performing loop
[/size][size=1.25em]      at Red Bull Air Race[/size]

    [youtube]1MfFStR_fA8[/youtube]

To play the game I voted "YES" because what they are selling as Coaxial Helicopters are, well lets face it "toys."
That said there was a DIY guy that scratch built a really neat Coaxial, about the size of a 500 in beautiful CNC aluminum ...
PS: also had variable pitched mains

.... had to admit it was a fine looking bird

I watched a number of videos the other evening while doing the post with the links. Most of those heli's just seem to big and heavy to be doing what they are. 

Here's one I missed. This would make a cool model.

http://www.youtube.com/watch?v=vfggwmhcvC0

Oh yeah, I forgot about that one. It's all over the Rotor & Wing magazine in almost every issue it seems like. It will be a while before it gets into production obviously. But being coaxial is what allows it to obtain such high speeds. There is no retreating blade stall since both the left and right sides of the aircraft have an advancing blade. So it can have a true rigid design instead of compensating by flapping (and stressing the hell out of things).

Oh yeah!  How cool would that be?

So let me get this straight: The blades DO NOT need a swash and the pitch DOES NOT change on the Sikorsky X2?

No, it has dual swash plates, it can control collective and cyclic pitch for each blade set. You yaw by giving it pedal input which equally adds and subtracts collective pitch for each rotor head. Adding more lift (more work) to one set, and less lift (less work) to another set causes a differential of torque, thus rotates the body of the helicopter, but maintains the same lift since you just shift the ratio a bit for a short time. For slow flight you just use cyclic pitch like any other helicopter, but once you are at the full speed that cyclic pitch can provide then the pusher prop takes over. I bet as they increase forward airspeed the collective pitch is reduced to nearly zero because effective translational lift will be huge at those speeds. Notice the blades are short? the disk area is doubled by having two disks, so they can be short and still maintain traditional disk loading, plus being short you can safely have a higher head speed and have the disks close to each other since they are so rigid. It's a big win win all around with that thing.

This guy did a nice job with his:

http://youtu.be/bKZVncMCd9E

Thank you.  That makes sense.

I would like to see some drawings of the swash setup for that X2 and see how they got the upper and lower blades so close together and also because there does not seem to be any linkages visible as with a conventional helicopter.

Would probably have to look up the patent for detailed drawings, but the linkages are either inside the hollow main shaft kinda like the tail rotor on a Huey:

http://media.photobucket.com/image/recent/ultrasauros/Rucker%2520B%2520model/UH-1B60-3554103.jpg

Or it is hydraulic/servo based control within the rotor head area, I am curious about the orange lines in this photo:

http://www.helicoptersmagazine.com/images/stories/News%201/May08/x2_groundrun_prep.jpg

But either way it won't be much, this is a true rigid rotor head, so rigid that if it was not coaxial you would probably crash with very little effort Without retreating blade stall there is no need whatsoever for any kind of flapping, so the only thing needed is feathering hinges to rotate into the desired pitch at the desired location, very simple actually. No flybar linkages, no designing for flex as with a semi rigid/elastromeric head, etc. And in the videos you can clearly see how responsive this thing is, the roll rate acceleration makes it look like an RC when it's hovering.

The other neat thing is that it has no issue with pedal turns, either way is fine, with tail rotor you must power one way, and allow torque to turn you the other way. One steals power to make the turn, the other steals power when you try to stop the turn. A trick pilots learn for Mtn flying when they can't do a running take off (when hot and high) is to get up to the upper edge of HIGE, then apply full pedal to remove all pitch from the tail rotor and climb while spinning in a circle. It gave those Vietnam boys just enough to up and away while overloaded, hot, and humidity.

Good points and thanks for locating that photo of the X2.  My guess is that the orange wires are sensor wires.  It looks like they might have been monitoring stress and/or acceleration or G-force, possibly harmonic, or all of these in the head assemblies and blades.

Your coaxial control (like the Huey) would work for the upper head and in the close up photo you provided it does look like there might be some control linkages for the lower head.

Here is a concept heli for the Navy, seems to look like something else we have seen before:

http://www.suasnews.com/2011/12/10356/fort-worth-firm-avx-aircraft-joins-bid-for-navy-contract/