Originally Posted by
TheReelDeel33
But what I do know about crop dusting are the basics... I'm pretty sure almost all the planes are taildraggers, and usually flown out of grass strips.
I only know of one tricycle sprayplane model (PAC from New Zealand), and it is hardly ever seen in the US. most are turboprop tailwheel singles. my experiance is mostly working from small paved county airports, with some work from roads. grass strips are not uncommon but not the majority either.
Your gonna be real heavy on take off, and climb performance might not be great.
true, in fact it is sometimes very bad. but you only have to claw your way to 300 feet. the first turn can be kinda hairy, but after not too many turns the aircraft lightens up.
Crop dusting involves alot of maunuevering at low altitudes (I consider altitude and engine oil a pilot's life blood so being low isn't for the faint of heart) and as you spray your weight is changing as well as your CG.
true about the maneuvering. think commercial standards steep turns but at constantly changing airspeed, starting and ending at 40-ish feet AGL with around 250 feet in the middle. with the little AT301 that i fly, i am going 145 across the field, get down to about 90 in the top of the turn, back up to 145 at field entry again. stall speed is about 80. in many ag planes (air tractors in particular) the flap settings change constantly in the turn as well.
yes, weight changes constantly during the spray run. however, the CG dosen't change very much. The hopper (and thus the load) is located right at the CG so as the load goes out, the cg dosen't change much. we do, however, have to constantly adjust power and trim to maintain the same groundspeed (notice not airspeed) across the field while spraying. (unless you have fancy variable rate spray gear.)
I see alot of cropdusting business moving midwest where there are still farms, and where EVERYTHING looks the same. I've flown out there once and compared to what I'm used to navigation was alot harder. You don't wanna focus in on a good spray, get confused as to where you are, and not be able to find your landing strip.
you do have to be able to find the particular field you are going to spray, and be able to tell different crops from the air. spray the wrong field, for example put roundup that was meant for roundup-ready corn onto someone's sugarbeet field, and you just cost your employer a LOT of money. not only on the lost product (sometimes the value of what is in the hold is more than the empty aircraft is worth) but in the lawsuit to settle the destroyed beet field. oh and don't even get me started on what happens if you put a load of 2,4-D or even pesticide on some "organic" field.
however, once you find your field, we almost all use differential-GPS systems to track our swaths with about 6-inch precision. imagine flying an ILS at about 10x the precision at 12 feet AGL. with rolling hills. and a pivot to clear in the middle. and trees at the end. and a crosswind.
We always try to work with a direct crosswind, because we need to keep the groundspeed constant so that the rate of spray stays constant from one pass to the next, and also so we get to fly through clean air, not through our own spray. too much wind and there are drift issues. too little wind and the spray just kind of hangs in the air and dosen't settle properly. (think low level inversion)
getting home isn't usually a problem. usually we fly out of the same strip or the same couple of strips every day, usually 10 to 20 or more landings a day. also the GPS system has a "home" waypoint.
most spray planes don't have a lot of endurance, and we don't go full fuel every time, so getting lost can mean landing in an other-than-intended location.
Not to mention the actual spray! Have you ever tried dropping something out of a plane into a garbage can? I did in a flying competition... until you actually try it, you don't appreciate how much the drag and wind really screws up your aim.
wind drift (of the product) is a huge issue. if you drift, you can have the same losses described above, plus drift can go onto a residential area and cause problems for people if you have just the wrong conditions.