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Orthopter

 from the Greek ortho - straight (instead of helik - spiral) and pteron - wing
  (+2)
(+2) 		  [vote for,
against]

This would be a helicopter-like craft with blades that move laterally instead of rotating. The orthopter, instead of rotor blades, would have four pairs of blades that extend out over its sides and oscillate from front to rear to front across its roof.

The absence of a rotor means no need for the superstructure and mechanics of a tail rotor, and main rotor problems of varying velocities between blade root and tip, and dissymmetry of lift would be avoided. The orthopter blade pairs with symmetrical airfoils ( <€ ) would ‘flip over’ at each outer point ( €> ) to maintain the same leading edge.

The blades could be driven with linear motors on parallel tracks as seen below from the side:

.....<€..... .....€>.....
€>.......... ..........<€

or:

..........<€..........
€>....................
..........€>..........
....................<€

or by an endless belt/chain similar to the treads of an upended tank:

..........<€..........<€
(------------------------)
€>..........€>..........

Two blade pairs are needed to balance each other's forward-backward movements and varying positions. Two more are needed to ensure lift when the other two are at their outer points and flipping over. Controls to adjust blade pitch and impart ‘flapping’ would be similar to a helicopter.

—FarmerJohn, Jun 03 2004

Ornithopter.net http://www.ornithopter.net/index_e.html
Like this? [FloridaManatee, Oct 04 2004, last modified Oct 21 2004]

Google http://www.google.c...UTF-8&q=ornithopter
28,000 more hits [FloridaManatee, Oct 04 2004, last modified Oct 21 2004]

flapping and feathering http://www.copters.com/mech/mr_semi.html
[FarmerJohn, Oct 04 2004, last modified Oct 05 2004]

Orinthopters can be useful http://www.brainbur...lt_card.asp?id=1514
[sartep, Oct 04 2004, last modified Oct 21 2004]

CarterCopter FAQ http://www.carterco...neral.htm#question1
See the answer to first question to understand why the Orthopter could be a very efficient aircraft. [scad mientist, Oct 04 2004, last modified Oct 05 2004]

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       [BB] Your paddle wheel plane link reminds me of my Hot wings foil airfoil idea. If you lose the tail rotor, have only four, longer blades per side, flatten and extend the paddle wheels from O to ======== shape and move them to the roof, then you're getting close. My space and time for drawing is limited.   

       [FM] No, the wings don't flap, they rapidly move back and forth in the same 'plane' as a helicopter's rotor. Helicopter 'flapping' is the angling up of one side of the rotor to change the angle of attack.
—FarmerJohn, Jun 03 2004
   

       +
—yamahito, Jun 03 2004
   

       I saw a lot of these ideas in early images of aircraft experimentation. I figure 100 years + would be enough to detemine if something like that would succeed or fail.   

       No vote from me either way, though till I have thought through it properly.
—FloridaManatee, Jun 03 2004
   

       This mode of operation also means harmonic-mode oscillation if you want any semblance of mechanical efficiency. Harmonics in structural elements are BAD! They lead to rapid fatigue and breakage.   

       If you can find a way around this, I'll bun it.
—Freefall, Jun 03 2004
   

       (+) for literal lateral thinking.   

       Thanks, but these blades don't flap like a bird (ornitho) but slice straight (ortho) through the air.
—FarmerJohn, Jun 03 2004
   

       You still will have advancing/retreating blade lift disparity which can be partially compensated for by increasing the angle of attack (incidence?) on the retreating blade.   

       Also, not sure what happens as the advancing and retreating blades cross over each other mid-cycle.
—bristolz, Jun 03 2004
   

       //increasing the angle of attack on the retreating blade// Exactly, or fly sideways.   

       //the advancing and retreating blades cross over// This must be a similar situation to the Chinook with tandem counter-rotating rotors or the Kamov Ka-52 with coaxial counter-rotating rotors.
—FarmerJohn, Jun 03 2004
   

       If I understand the drawing and explanation, the blades reverse direction at the end of each stroke which is is a lot of wasted energy and puts tremendous strain on the rotors.   

       Having 2 coaxial counter rotating rotors does the same thing without the enefficiency and strain as well as being mechanically much simpler.
—macrumpton, Jun 04 2004
   

       Mechanical simplicity is often not a hallmark of halfbakery designs.
—bristolz, Jun 04 2004
   

       [Freefall] I would think these oscillations would be least in the upper diagram where the forces and movements are symmetric.   

       [macrumpton] Much of the energy should be able to be regenerated in the upper linear motor examples when slowing the blades towards the ends to be reapplied for acceleration (such as some monorail trains). I don’t take this machine too seriously since it’s in the halfbaked zone.   

       [Steve] I wonder if it’s possible to lift an aircraft purely by it blowing intensely over its airfoils.
—FarmerJohn, Jun 06 2004
   

       Sure, helicopters do it ;-)
—bristolz, Jun 06 2004
   

       Apart from more vibration, mechanical inefficiency and complexity. Once it gained some forward speed, it wouldn't take advantage of the airstream. Besides, in case the system fails, the plane would inevitably crash. This is not the case with a helicopter or a traditional airplane. (Considering this the planes should actually move with the longitudinal axis and not side wise. Of course when they move backwards they would need to be covered.)
—Globi, Jun 08 2004
   

       // Considering this the planes should actually move with the longitudinal axis and not side wise. Of course when they move backwards they would need to be covered // [Globi] I think this is actually how he intended the plane to work. But there is no need to cover the retreating blade, even in high speed flight. Assuming there is also some kind of propeller or jet for additional forward speed, as this aircraft came up to full speed, the blades could actually be slowed down and possiby stopped so they would be used as normal airplane wings. The blades/wings could be sized to be efficient at some fairly high cruising speed, allowing this plane to be quite efficient. That's how the CarterCopter is supposed to be able to get really high efficiency (see link).   

       Regarding engine failure, if the baldes aren't oscillating, the stall speed would be way to high to make safe landings. Luckily, assuming there is some mechanism to avoid loosing all the energy in the blades as they changes direction, the blades should be capable of auto-oscillation (similar to autorotation), allowing the aircraft to land safely with no power.   

       I do have to agree that the mechanical difficulties of rapidly and efficiently reversing the direction of blade movement will make implementation difficult (impossible with current technology?), but hey, this is the halfbakery. [+]
—scad mientist, Jun 08 2004
   

       if the wings flip over at the end of each stroke does that not mean that the aerofoil is upside down and therefore creating downward force. or have I completely lost it?
—etherman, Jun 08 2004
   

       Use symmetrical airfoils.
—bristolz, Jun 08 2004
   


 

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