Limitations on Tractor/Combine Design
Limitations on Tractor/Combine Design
(OP)
I have never had any experience with farming or tractor design per se, but I was trying to figure out what limitations are placed on design of Farming machinery, and why not go way bigger. With farms becoming corporate, are we looking at farming machines going the way of mining/quarry machines and becoming superhuge? I figure size limitation probably has to do with the requirement of being able to drive down a narrow dirt road with overhead wires, is there a standard weight limitation or other limitations to sizing a new tractor or combine design?
I am wondering it an aircraft could be designed to do some serious farming. I am thinking about a low speed flyer, with about 4 engines, and multi-tailboom design. It would be heavy and have a ton of drag, but you could have an enormous wing with controlled attachments for doing the cutting/tilling/ whathaveyou. Nothing like it has been done before to my knowledge, but I would compare it to a slow B-52 with no wing sweep, narrower & shorter fuselages, and huge tires. I honestly don't know enough about the ag market to find out if it would be cost effieient do design a fleet of these beasts, but I think it would be a cool option to go bigger.
Thoughts? Comments? It is a totally crazy and impractical idea? Assinine to even pursue marketability?
If anyone could provide some resources online I might not be aware of, or some good specific references to get an idea of the mechanical terminology, mechanical systems and design parameters of tractor/combine/ farming machinery, that would be helpful, especially dealing with price/cost parameters associated with tractor design. ($/acre, section; $/hr; $/year, lifecycle, etc)
I am wondering it an aircraft could be designed to do some serious farming. I am thinking about a low speed flyer, with about 4 engines, and multi-tailboom design. It would be heavy and have a ton of drag, but you could have an enormous wing with controlled attachments for doing the cutting/tilling/ whathaveyou. Nothing like it has been done before to my knowledge, but I would compare it to a slow B-52 with no wing sweep, narrower & shorter fuselages, and huge tires. I honestly don't know enough about the ag market to find out if it would be cost effieient do design a fleet of these beasts, but I think it would be a cool option to go bigger.
Thoughts? Comments? It is a totally crazy and impractical idea? Assinine to even pursue marketability?
If anyone could provide some resources online I might not be aware of, or some good specific references to get an idea of the mechanical terminology, mechanical systems and design parameters of tractor/combine/ farming machinery, that would be helpful, especially dealing with price/cost parameters associated with tractor design. ($/acre, section; $/hr; $/year, lifecycle, etc)





RE: Limitations on Tractor/Combine Design
Planes are used in modern farming for liquid application of fertilziers, pesticides etc. This is a reasonable use because reduced soil compaction increases production.
I could envision a ground effect vehicle such as a hovercraft doing mowing or something to reduce compaction but it would only work in very flat areas.
RE: Limitations on Tractor/Combine Design
A flying tractor would be a very expensive program, but it seems like tractors are getting more expensive, farms are getting larger, and particularly I want to project a crossover point where tractors can't get any bigger. I am looking for a resource for economic data for tractors re costing and price for a program of a certain number of tractors. Maybe ag industry doesn't work that way, I don't know.
I have some other projects going on, so I haven't had any time to work on developing this other than thinking it out in my spare time. I know it could designed, I just don't know if it would be worth it, and that really depends on size and cost, which are directly related.
RE: Limitations on Tractor/Combine Design
RE: Limitations on Tractor/Combine Design
Same thing with seeding, zero till or minimum till combines cultivating, seeding and fertilizing into one process. The amount of grain & fertilizer being hauled around is a major reason why such large tractors are required.
RE: Limitations on Tractor/Combine Design
not to mention you need to move air over the wings to produce lift,
You need to study real time equipment not theroy!
SBI
Central Ne.,USA
RE: Limitations on Tractor/Combine Design
The John Deere 9620 has about 500 HP and weighs about 40,000 lbs. So you are saying a large tractor roughly of that size and power cal pull about 360,000 lbs? Good to know
The same powerful turbine engines in a 747 can also be used to turn a driveshaft or an axle. Aren't these are the same types of turbines that turn an electric power generator producing up to 480MW? There are several vehicle/motorbikes that use a turbines as a powerplant. The nice thing is that with a turbine engine you can realize about 99% of the ideal Brayton cycle efficiency.
However, I was kind of leaning toward a diesel motor with electric transmission - as used in train locomotives. The diesel motor would also be able to turn a prop I think - however I haven't got that far yet.
sbi, your post gives me an idea - a Convair XB-36 Bomber used caterpillar style track landing gear - I'll work that in and it is a useful thought. Also your link to http://tractortestlab.unl.edu/ on another post will probably be useful.
I think as long as there are naysayers, I will keep thinking about this and continue on my preliminary design. Nothing has been done like this before so it is hard to compare to existing vehicles, tractors or aircraft, and it is why I find it an interesting puzzle to work on in my spare time. Thanks
RE: Limitations on Tractor/Combine Design
RE: Limitations on Tractor/Combine Design
The turbine-in-a-tractor bit is relatively commonplace among the tractor pulling crowd.
What you propose has a mix of variables that interact so highly that almost inevitably the decision is made to favor one area over another.
Aircraft as spray equipment only became feasible when chemicals were concentrated enough to allow enough acres to be covered. Still today, the plane spends more than maybe half of its fuel on turning and reloading.
Let's say your machine has a ground speed (yes I realize it is flying but the effective speed is gs)of 60 mph and a tool width of 20 feet. For easy calcs, the field is one mile long. Each pass covers 2.42 acres. @60mph, 100 bushel/a yield, 56 #/bu this means that the equiptment increases its gross weight by 13,500#/min. Add to this fact that the "combine" portion must process this at the same speed. This rate equates to harvest speeds in the neighborhood of 145 a/hr. There may be farmers willing to pay for that kind of speed but remember that you will be lucky to get half of that, more likely 30%.
Have at it!
Griffy
RE: Limitations on Tractor/Combine Design
RE: Limitations on Tractor/Combine Design
In transfer from completed field to next field to be completed we fly. Advantage is speed of transportation between fields, and once again, reduction of effective size limitations due to enviornment variables such as GVW limitations, overhead power lines, and narrow unpaved roads.
Reagarding the B-36, the XB designation usually means eXperimental aircraft, and the experiment in this case wat to develop and proof the concept of track landing gear for heavy aircraft. Here are some cool pictures: http://ww
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I remember learning about this in aero design class, and sure enough it is an option especially useful for a heavy vehicle operating in dirt.
I started with configuration layout yesterday to get a picture. I have some ideas, but I need more information still.
Is aluminum used ever or fairly often in tractor structures? I would imagine a lot of the parts are steel or cast iron.
RE: Limitations on Tractor/Combine Design
RE: Limitations on Tractor/Combine Design
I fear with current technology the flying tractor would use too much fuel with turbine engines. With fuel prices how they are, profit margins are razor thin for farmers and they would have to have a really good reason to use more fuel to do something even if it saves some time.
RE: Limitations on Tractor/Combine Design
I am thinking this aircraft is going to be a harvester or combine, not a tractor. I like the option of deisel, since most combines use diesel now anyway. It is really hard to size this thing though because of the problems noted with uneven fields and lack of data on flying harvesters.
I believe that when I get into it, there will be a breakpoint where a minimum size will be profitable in terms of harvesting seasons and and aircraft program lifetime. Of course it is a gamble still because of unstable gas prices, crop futures, and future technological developments in the industry. Hopefully that minumum size is less than a 747 in terms of winsgspan.
I like telling people about my idea for a flying tractor, They usually seem politely amused by it. I think I'll name the project "Locust" for now.
RE: Limitations on Tractor/Combine Design
Steel is generally used in many ag applications for 3 reasons:
Weight isn't generally a problem and if it is a HSS gets close to the strenght to weight ratio of many materials.
Infinite fatigue life, aluminum has a finite fatigue life and farm equipment has to last a long time.
Easily Repaired with standard welders and techniques familar to farmers.
RE: Limitations on Tractor/Combine Design
RE: Limitations on Tractor/Combine Design
You would have issues with weather etc, but these would be similar problems with the flying tractor, as it would also be on the limit for flying.
RE: Limitations on Tractor/Combine Design
I just started a new job, so I probably won't have as much time to sit around and think about these things anymore. At least I hope not, one of the reasons I changed jobs is because of lack of things to do to utilize my engineering mind, so I would sit around and think about flying tractors among other things. It still has some merit I think, and I will continue to learn about farm equiment and work it out.
I like balloons for certain things, I would like to see a comeback of zepplins and blimps for transportation, and they are coming back for unmanned remote sensing applications - but it is easy to underestimate the amount of lift you can get from a wing - and given the weight of the steel combine header alone, wings can do that better than balloons.
I think it could me done even more efficiently and synergetic from a from scratch combined design. It would also probably lead to new ideas regarding both aircraft operations on the ground and farming equipment even in the event of design failure - but it has a long way to go.
RE: Limitations on Tractor/Combine Design
RE: Limitations on Tractor/Combine Design
I like the ballone for some of these applications. How do you steer the balloon. Or just use to reduce soil compaction and working wetlands.
Drkillroy
RE: Limitations on Tractor/Combine Design
Thanks Drkillroy
RE: Limitations on Tractor/Combine Design
what you are referring to is called ground effect. It applies over land as well as water. Ground effect vehicles (GEV) can operate only in this area. I think the height above groud in which GE occurs is about half the wingspan.
RE: Limitations on Tractor/Combine Design
There is also less fertilizing required due to not exposing as much topsoil for erosion loss during the off season.
The smart sprayers will also minimize the amount of herbicides put down on the fields as well in the future.
It is funny to see the big corporate 4x4 tractors sitting around rusting away.
RE: Limitations on Tractor/Combine Design
The thing I would think important is the loss, not using a real runway. Those quick deployed equipment of the military get ruined alot. I don't know what the numbers are but insurance might be a problem.
_______________________________________
Feeling frisky.........
www.tailofthedragon.com
RE: Limitations on Tractor/Combine Design
"Smart Sprayers" Tell me more about the way they work? Years ago I heard of mounting microphones next to the nozzle to send an alarm if the sound of the spray changes! What else is going on?
Drkillroy
RE: Limitations on Tractor/Combine Design
RE: Limitations on Tractor/Combine Design
RE: Limitations on Tractor/Combine Design
Several universities and experts in agricultural/biosystems engineering are working together to master this technology to where it can be economically feasable for the average farmer. The faster computers of today compared to 15 years ago is helping this technology a lot.
RE: Limitations on Tractor/Combine Design
Hold up -- not even close. The coefficient of friction between soil and rubber is ~0.7. A 40,000lbs tractor can only exert a constant pull of ~28,000lbs, give or take. I used to use this fact to verify that my load cells were working correctly. And then the soil can only "hold" a certain amount of force before the tires begin to spin. After you have enough rubber on the ground to avoid excessive spinning (~7-10% is optimum for tires, 3% from tracks) more tires can be used to minimize compaction. You generally get higher draft loads when the machine first engages the ground due to momentum, but that only lasts a split second. As you can see, if ground drive is utilized you would need a lot of weight to pull a large ground engaging implement.
As for turbines, IH built two prototype turbine tractors sometime in the 70's. From what my coworkers said they were ungodly loud, it was difficult to modulate engine speed, and they required lots of fuel. They donated one to the Smithsonian and I think they still have the other in their private collection.
RE: Limitations on Tractor/Combine Design
http://gontek.blogspot.com/
at this link to my new blog I posted a couple images of my preliminary configuration attempts. I would probably normally do about 20 more configuration layouts before I considered weight, balance, pros and cons, and went with one. I would pretty much have to do a whole detailed design before I could estimate costs with any accuracy, and it would probably be more than 10 billion for 500 machines, I would wildly guess. enjoy, and thanks everyone for your comments, shared knowledge, and time.
RE: Limitations on Tractor/Combine Design
Dang it, I'm doiing it again, I am thinking about it.
RE: Limitations on Tractor/Combine Design
With fossil fuels becoming ever more expensive we will
I think downsize tractors as the emphasis will be placed on no-till.
I'm moving that way and saving money already.
The other changes in future will be more sun-migration and more people growing their own food on small holdings as the traditional role of cities diminish due to the cost (and lack) of oil affecting all transport systems.
There may be a role for smaller planes in agriculture but certainly not for primitive activities such as ground engagement.
EJ
RE: Limitations on Tractor/Combine Design