Combines 9010 or bigger IJ

Yeah you probably have a point there ive not thought of that

IJIJIJHuhIJIJIJ What are you talking aboutIJIJ How do you come up with 30" as ultimate practical feasabilityIJ You might be supprised how much of an "idea" some of us have.

I think Rooster is referring to the amount of additional horsepower it would take to increase rotor rpm's to equate similar centrifical force between a 30" rotor and a 40" rotor. I KNOW this was a factor when White and Massey were both developing the original 9700 and, in MF's case, the prototype TX903. I don't know how one would come up with "ultiamte practical feasibility", but I DO know that both White and Massey were both concerned the 30" rotor (at that time) might be overkill, especially when they were only using 250 horsepower engines in thier prototypes.

I didn't say that a 40" rotor wouldn't work, but the cost to power a combine with a rotor much over 30" would price the machine well out of reach of most. The engine atop most combines, albeit standard equipment, it at least $25K+. To jump up a 3-5 litres to get enough torque and horsepower would cost one big bundle, more so than what most would probably be willing to pay.

It had a 36" rotor, and a a full 10' length. Yeah, the horse power was a limiting factor on that machine only for the fact that they were running everything with hydro motors. The next generation was to have many of the hydro components replaced with mechanical. The feeder drive was to run the full length of the machine and the hydro-mechanical drive of the current 8010 was in the works then, just a prototype version was run for the last season on that machine. The dual side unload was going to go by the wayside as the weight and complexity made it difficult to operate and manufacture. The unload rate though was planned (and tested on a portable stand) to achieve 5 bu_ sec. It was not only front wheel steer, you might bwe remembering the ARCUS out of Germany that was brought over for a short run in 1998 or 1999. The Case machine was full 4 wheel steer, with the option of crab steer for hillside operation. With 425HP, the thing would flat out eat corn in a hurry. Hardest thing was keeping it full to keep the grain off the ground.

Ok, so a 40" rotor may still work, just other issues need to be addressed first. Ok, thanks.

Wouldn't just adding a bigger clean grain capacity to the machine do the trickIJ

The weight will be the stopping point and actually we are past that point. A big machine uses more fuel just for propulsion than a small machine uses to shell and move. The price of fuel will force the size of machines to go smaller again. Just like the Concorde and the SUV

To maintain the same tip speed for a larger diameter, the RPM would decrease. Rooster, per your post above, I think you are correct in that torque (ft - lbs) increases to keep the rotor turning at slower speeds. Some additional HP is usually required to do this, but the increase is not an "exponential" increase as you stated, but rather a more "linear" increase. On the other hand, Fc (Centrifugal force) does increase exponentially, as velocity increases as defined by the formula Fc = W (weight of grain) x V2 (Velocity squared) _ divided by g (gravity) x radius. V2 (V squared)represents a "exponential" increase in value of Fc, Centrifugal Force. Hence, perhaps the best way to increase separation capacity (Fc) in the future for rotary combines is to increase velocity by turning the outer cage in the same direction as the crop mat via a bi-rotor configuration. The velocity of the crop is the sum of crop mat speed (usually about half the rotor tip speed) plus the outer cage speed. One additional drawback of just increasing rotor and cage diameter is the associated increase in unused volume lost inside the larger rotor drum. It is unused dead air space deep inside the combine already. Increasing rotor diameter adds to the space waste. Hence two smaller, 17" or 22" diameter rotors create more Fc, more separation grate area, and requires less torque to turn than one larger rotor. This seems to contribute to the lexion's top end performance in todays market. Distribution to the shoe is spead over a wider area, and less vertical height is wasted with the two smaller diameter separaton rotors.

I'd enjoy arguing the wasted space with you, but it would be better to do in person. Maybe someday.