| Author | Message | ||
     Diablobrian |
What do you guys think of this? http://www.reverserotatingrotors.com/index.html The concept seems a little thin to me. More info here. (Message edited by diablobrian on February 16, 2006) Fixed long/broken hyperlink. Blake  (Message edited by blake on February 16, 2006) | ||
| Chiefiron |
Well if it’s true where do I sign up? Website is really thin if you had such a huge invention that would change so dramatically the entire motorcycle industry wouldn’t you spends a little more time on the web site? Add a few flashy pics or drawings? Tim | ||
| Blazinc5 |
Well, it's an interesting idea, but I find it hard to believe it works like the claims. Think about it. Going in a strait line the force of the wheel spinning is yup a gyroscope, we'll call it a vertical force.. ok add the rotors spinning in a reverse rotation,,, Hmmm looks again like vertical force. Either way as speed increases, force on the outer diameters increases. So no matter what direction the wheel vs. the rotor travel they are still in the same alignment. giving off that vertical force.. Having something spinning in a horizontal momentum I could see how just maybe it would help with the steering... But I just can't fathom a horizontal rotor. Thinking about some of the added parts, such as a gear due to a reverse rotor makes me wonder what would happen if it should fail. Gears tend to bind before they break where as bearing tend to vibrate real bad or pop out the sides of the race giving ya at least some warning. Can anyone say big huge liability? | ||
| Trojan |
The biggest question in my mind is: How will they get the disc to rotate backwards at the same speed as the wheel, without adding huge amounts of weight in the form of motors etc? The other point is that the rotor will always be a smaller diameter than the wheel, so the forces won't be equal anyway. (Message edited by trojan on February 16, 2006) | ||
| Cowboyup |
I'm no physasist,but I do not believe counter rotating gyroscopes cancel each other's gyroscopic effects. In my opinion the prescession caused by each of the counter rotating masses would be added together and result in the same force that is created by two spinning in the same direction. | ||
| Josh_ |
and it isn't even April 1 yet | ||
| 99buellx1 |
That website sucks. | ||
| Sarodude |
Let's say that they can "gear" the rotor(s) to turn in any fixed proportion relative to the wheel speed. Does the whole angular momentum thing increase linearly with speed / radius / mass? I'm asking strictly out of ignorance. If it's not linear, then it would seem that there would be only 1 speed at which the forces would completely cancel out each other. -Saro | ||
| Bomber |
Cowboy -- think think that they DO cancel each other -- I'm thinking of a number of aircarft developed at the end of the piston engine/propeller era, and one of the benefits of having two counter-rotating props was the greatly diminished torquing of the aircraft more strongly felt at takeoff/landing, just when you don't want it) due to the mass of the prop while the baseline science of this concept may be sound, after reading what little data is available on the site, a couple of language usage things leave me doubting if these guys are physisists or engineers capable of developing the idea in any sort of a reasonable way | ||
| Josh_ |
Do you think the addition of all that unsprung weight not to mention manufacturing tolerances will make this worth while? | ||
| Court |
>>>>torquing of the aircraft And "p-factor" . . . I still, out of habit, press on the left peg of a motorcycle as it leaves a jump. | ||
| Court |
>>>>motorcycles are never laterally stable. I read that and frankly, I want to say I am skeptical, but will settle for saying "I just don't know". The wonder of teams and collaboration is that I do know someone who does know for certain. He wrote his Master Thesis on the stability of two-wheeled in-line vehicles. I'm sure he's read this. He has, to quote the 6 million dollar man, "the technology". If there's anything to it, I'm sure we'll hear more. At the very least, I enjoy reading things like this that make me think as I read. | ||
| Sweatmark |
The question of gyroscopic stability has been addressed for single track vehicles (bicycles, motorcycles): http://www.velonews.com/media/Block40.pdf http://www.wooster.edu/physics/JrIS/Files/Brad.pdf http://www.people.cornell.edu/pages/aed29/Bad_Mechanics.htm There's some additional discussion in "Bicycle Science": http://www.amazon.com/gp/product/0262731541/102-0641308-9724165?v=glance&n=28315 5 Reduction of front wheel's angular momentum should reduce steering effort, but at what cost in high speed stability? Easiest means of getting counter-rotating disk might be simple bevel gear set, egg beater style, with concentric wheel & rotor axes. Putting it all together would require gear box for lube containment, additional bearing sets for rotor(s) and center gear. Additional (unsprung) weight would include: gears, bearings, housing. Would quicker steering be worth the additional weight? Mark Oregon | ||
| Blake |
Counter-rotating gyros do indeed have a reduction/canceling effect. The topical web site states that the counter-rotating brake disks are spun faster in reverse in order to be able to cancel the inertia of the wheel and tire which is much greater. Gyroscopic effect increases with angular velocity, so if the inertial of the wheel/tire is four times that of the brake disks, teh brake disks would need to counter-rotate at four times the speed of the wheel in order to eliminate all gyroscopic effect. I agree that the penalty in unsprung weight would seem to be prohibitive, but maybe not. Would be interesting to see a sketch of the mechanism involved. Of course there is still the even bigger rear wheel/tire and the engine/flywheel with their gyro effect. Some really wierd things could happen if one were to eliminate gyroscopic effect from the front wheel and not the rear. Or not. I dunno. Fun/interesting stuff though for sure. Here's a good discussion on the subject of gyroscopic wheel effect... http://www.people.cornell.edu/pages/aed29/Bad_Mechanics.htm | ||
| Gearheart |
It might work though I would certainly like to see some pictures on their website on the other hand its yet more mass to spin up while accelerating so there will be some, probably small but still, loss of outright acceleration. | ||
| Adrenaline_junkie |
Counter rotating flywheels (be them tires, wheels, brakes or whatever) do have a canceling effect on each others gyroscopic effect BUT ONLY IN THE PLANE AROUND THEIR AXIS OF ROTATION. In all other directions (such as leaning the bike into a turn), they would have an additive effect. (twice as hard to lean the bike over) The counter rotating propellers immediately after WWII were a perfect example of the cancellation, but note that the axis the propellers turn around runs down the middle of the airplane. Canceling the forces around the front (or rear) axle of a motorcycle won't do anything to make it turn better. | ||
| Blake |
"In all other directions (such as leaning the bike into a turn), they would have an additive effect. (twice as hard to lean the bike over)" Are you sure? There is no gyroscopic effect in the plane of rotation. Resultant gyroscopic effect manifests only orthogonally to the plane of rotation. If you have two equal but counter-rotating gyros affixed to a shaft, it seems to me that you will observe ZERO external gyro effect which is to say that outside the internal forces experienced by the shaft itself, you would see or feel no gyroscopic effect. The opposing gyroscopic forces (moments) however would be trying to bend the heck out of the shaft. Were not counter-rotating props primarily concerned with canceling the torque generated by the drag of a lone spinning propeller, not its gyroscopic effects? Without counter-rotating props, some aircraft would roll over while on the ground due to propeller driving torque. Open the throttle for take-off and the plane would roll over. Not pretty. For the same reason, helicopters employ a tail rotor to cancel the torque generated by the spinning main rotor. The tail rotor also of course aids attitude control in hover scenarios. (Message edited by blake on February 16, 2006) | ||
| Bomber |
Brer Court -- good plan, unless your flying a Typhoon (a guy augered in after flying a Corsair for years -- seems Typhoon motors spun backwards) AJ -- good point -- I think you're right, it would not have a beneficial affect, unless making your stoppies easier | ||
| Blake |
The equation appears to be a simple one... Where M = moment or torque w = precession rate p = gyroscopic spin rate I = gyroscope's mass moment of inertia about its spin axis From the above, can we not see see that if we have two counter-rotating gyros, one with pI=(+X) and the other with pI=(-X) affixed to the same shaft and so forced to precess at the same rate w, then the resulting moment (M) is zero? Where am I wrong? | ||
| Adrenaline_junkie |
My mistake. I was thinking about inertia instead of gyroscopic effect. | ||
| Blake |
Consider two counter-rotating gyros as described above. For gyro #1 we have: M1=w(+pI) For gyro #2 we have: M2=w(-pI) Thus M1+M2=wpI-wpI=0 No resultant gyroscopic forces. Bomber, My sense is that doing a stoppie would actually be more difficult as the amount of braking power required to slow the spinning wheel and higher speed counter-rotating disks would demand even more braking power. Conservation of angular momentum rules the day, no matter if parts are spinning opposite or not. In other words, there is no free lunch when it comes to stopping a spinning wheel. If you add inertia to it, it will require more effort to stop it from spinning in the same amount of time. This is fun stuff! | ||
| Blake |
Gyroscopic effect is NOT intuitive. It is more like magic. Still makes my head hurt when thinking about it. | ||
| Henrik |
Don't know the formulas, but do remember my childhood experiments: holding bicycle front wheel by both ends of the axle. Spin said wheel. Observer resistance to tilting. I somehow can's see the two opposite rotating wheels not resisting - but I could be wrong ... it'd be the first time ever, but it could happen In your formula, Blake, I'm not sure I see a specific value indicate direction of rotation?? And if that was the case, then wouldn't it have to follow, that a wheel spinning a particular direction would resist movement in one particular direction as well? If their theory was correct, then wouldn't a counter-balancer spinning opposite the flywheel have the same effect? Henrik | ||
| Bomber |
blake -- you are very likely right -- we have now gotten to the point where it becomes obvious why I became a technical writer ;-} | ||
| Tank_bueller |
my $.015 Blake, that works fine and I agree that counter rotating masses(such as props, wheels, etc) cancel each other out as far as torque(M) on the axis of rotation..... But, when you try to move the axis of rotation, you still have all that mass spinning around the axis. I don't believe it makes a difference which way they are spinning, it seems that twice the spinning mass would make it twice as hard to turn the axis of rotation. or somethin' like that  edit: slow typer should be easy enough to put together a couple of rotating masses on a stick and try it out (Message edited by tank_bueller on February 16, 2006) | ||
| Djkaplan |
This idea was actually used in GP racing in the mid-70's by, of all manufacturers...Harley-Davidson(!) on rebadged Aermacchi's. It was quickly abandoned, too. There is an example of one at the Barber Motorsports Museum. Nothing new here, nothing new at all. | ||
| Blazinc5 |
I'm gunna try to put my machining skills to work and make a test toy... providing I can find some decent scrap metal at work.... then get time on the lathe... lol This has sparked my interest oddly enouph... | ||
| Blake |
Henrik, The spin rate follows the right hand rule and so in the case of counter rotating gyros, one would have a negative spin rate. It is a vector quantity and so has magnitude and direction. The descriptor "spin rate" is actually inaccurate, it is most properly termed angular velocity. De math dohn lie. Example: Take your forward spining bicycle wheel and try to turn it as though you were making a left hand turn, toward the left or CCW looking down upon it. The gyroscopic reaction is that the forward spinning wheel will tend to precess in a manner that will lean it over as it would in a left hand sweeping turn. Now do the same but with the wheel spinning backwards, opposite from before. Now if you try to turn the wheel to the left, it will tend to lean to the right, exactly opposite of before. Cool eh? Tank, It is two entirely different and unrelated mechanisms. Trust me on the gyro thing. Counter-rotating gyros are canceling not additive. Honest. | ||
| Blake |
First time ever wrong? Cool!  Bomber, It's just book learning, this type of thing. You'd be great at it I'm sure. If you could stomach it. I thrive on it.  | ||
| Adrenaline_junkie |
The direction the top is spinning does matter. If you have a top that is spinning, and the top of the top is off center, the center axis of the top will "gyrate" in a slow circle. (the precession in Blakes equation) This gyration will always (according to my reference material) be in the same direction as the spin of the top. If the top is spinning clockwise, it will gyrate clockwise and counterclockwise if it is spinning counterclockwise. Some points to note: 1. In all of the examples where the above equation (and several others) are used to describe the motion of the spinning object, one end of its axis is fixed at some distance from the spinning mass. (this is not true on a motorcycle) 2. The spinning mass is supported only by its axis and the gyroscopic effect. (the edge of it is NOT rubbing against the ground) 3. Loads (such as the weight of the motorcycle) are not being applied to to the spinning mass through its axis (axle). How does all of this affect the handling of a motorcycle? I have no earthly idea. I've never noticed the gyrating of my tires as I turned so I don't no how canceling it out would change anything. Perhaps the gyrating (precession) is the cause of tank slappers, but that is only my speculation. Reading the link to Cornell above, I get the impression that the trail (caster) built into the front end of the bike negates the precession. I still feel that the most significant factor here is that you would be increasing the unsprung weight and the amount of mass that has to be leaned over and then picked back up to make a turn on a motorcycle traveling at speed. |
