- Going Smaller? 60’ to 8’ implement
OK so let’s assume that we have all the technology to have autonomous tractors; and we do. The operator would be just sitting on the tractor with nothing to do but go along for the ride; but, not really necessary. So, let’s say we remove the operator; what are the ramifications. Obviously, if we don’t need the operator, we don’t need all the cab and all the operator amenities; but that is nothing compared to the realization that the only rational reason for having large, and I mean really large equipment is because of the operator. To best make use of the operator’s time, one must have large equipment. However, if an operator is no longer required, then all rational logic leads to smaller equipment. Some say that larger equipment is more efficient; but this is only in terms of the operator’s time. If there is no operator, this is a moot argument. I would like to demonstrate that smaller equipment is more efficient, more reliable, less costly and more convenient than larger equipment.
Let’s be specific; let’s compare a 60 foot and an 8 foot piece of equipment working a quarter section (160 acres). How much overlap will occur? Let’s assume that the lateral overlap has been eliminated with auto-steering, and that ideal turns can be made in the headland. Comparing the area covered in the headlands, it is found that this covers a half a circle for every one width pass, or a full circle for every double pass.
A quarter section is a half mile by a half mile (5280/2 = 2640 ft). A 60 foot applicator needs 2640/60 = 44 single passes, or 22 double passes. Each double pass requires a full circle area of radius 60’ = p 602 = 11,310 ft2 whereas the 8’ implement requires 2640/16 = 165 double turns x p 82 = 201 ft2. In finishing the field, the last pass would be, on the average, half an implement width, resulting in 30 x 2640 = 79,200 ft2 for 60’ and 4 x 2640 = 10,560 ft2. So a 60 ft. double covers an area of 11,310 + 79,200 = 90,510 ft2. Whereas a 8 ft implement would double cover 210 + 10560 = 10,770 ft2.
A quarter section is 6,969,600 ft2. 60’ has 90,150/6,969,600 = 1.3% double area coverage, whereas the 8’ is only 0.15% double coverage.
Another way to look at this is one would expect that a 60’ implement, going the same speed as the 8’ implement would take 7.5 times the amount of time to do a quarter section. (90,510 + 6,969,600) / 60 =117,668 time units. Whereas the 8’ would require (10,770 + 6,969,600)/ 8 = 872,546 or 7.41 not 7.5.
Taking the operator off the machine means we don’t have to cater to the operator; we can work 24/7. Assuming that an operator needs to eat, sleep, and take occasional rest breaks, let’s say we have 12 hours out of the day that he is actually driving. So, to do the equivalent of a 60’ machine only half of the 7.41 8 ft machines or 3.7.
When we have an operator driven machine, we must provide some over capacity to ensure the job gets done in case the machine or the operator break down. However, there is reliability in numbers. If the 60’ machine breaks down for a week, you are doing nothing for a week. However if an 8 ft machine breaks down for a week, and you have 4 of them, you still have 3 good ones working, or 75%. I would be so bold as to say that three 8’ machines working 24/7 would do as much work as the one 60’.
Smaller is cheaper. Let’s say that the 60’ cost $120K and that half the cost of a tractor goes into keeping the operator happy. So an operator-less 60’, without cab etc. would cost $60. Let’s also assume that the cost is proportional to the number of feet that the implement is. Therefore an 8’ would cost $8K and three 8’ would cost $24K. So, going from driver to driverless can save an enormous amount, $120K to $24K.
Operating costs could also go down. We don’t have to haul around the extra weight of the cab and we don’t need to provide 15 HP for air conditioning. If tendering can be done more frequently, smaller amounts of fuel, seed, and other inputs need to be dragged around the field. Reducing the speed of the machine, can greatly reduce the amount of energy required as well as the weight of the engine. Just roughly, I would think that fuel costs could easily be decreased by 10% or more.
The bottom line to all this, is that having a driver, as opposed to having an autonomous system is that: having a driver is a very expensive proposition.
An 8’ machine is also easier to work on, is less onerous in terms of safety, and is easier to transport when one consider the legal 8’ width for any road, highway or bridge. And with less weight comes less soil compaction. Many, many advantages to go small.
Less compaction, easier to store, easier to fix, we are down to less than 1% of overlap in headland therefore we can accommodate smaller fields with sloughs, trees, shelter belts and other obstacles with little consequence. Going smaller is environmentally friendly.