Turbine AgCat SS Spray Booms, Part 1

admin

Blackbird Product-Turbine AgCat Spray Booms7-7-07Most folks have never seen a crop duster, up close. In California, these and crop dusting helo’s are the workhorses of agriculture. They spread the seed (rice), spread dry fertilizers, sulfur, insecticides, fungicides, weed killers, anthrax powder, etc. The ‘spreader’ is outlined in the blue rectangle below. That big thing, is coming off, next week, with the revised spray boom assembly, now used for liquid application.    Below is Twin Cities Aviation, Turbine AgCat, a purchased used, last fall, getting more upgrades and mod’s. The long, impressive ‘shark nose’ on these turbines, is the same engine nacelle used on the King Air twin turbo prop. Cockpit now has air conditioning! This isn’t a frill, since it gets very hot, and normally is flown with windows shut. For rice seeding over the flooded fields, a pilot may be flying loads, continuously from sunup to sunset, in May. The seed is already wetted and just beginning to grow, prior to loading in the white outlined hopper-tank rectangle below—so time is of the essence. The hopper-tank (white outline) on this plane, I believe will hold 2000 lbs. The load is lightened as the heat of the day increases. Take-offs and landings for reloading, refueling are done on short little, rough, dirt strips, some only 10’ wide located around the fields. Every landing and takeoff, needs to be ‘good’; or the plane crashes. Crop dusting planes are built extremely tough. Pilot is inside an elaborate, chrome-moly cage (the entire airframe is chrome moly tubing), everything in the plane’s structure is built heavy, to last and endure. Rudder pedals are huge, cast aluminum footplates (for wearing heavy boots)-when getting in the cockpit and seeing these for the first time, I realized this is a real ‘He-Man’ aircraft!    The red circle is a wind driven, propeller pump for pressurizing the liquid in the tank-hopper, to spray out the booms, hanging below the wings.   http://www.weldingweb.com/attachment...1&d=1196040276Flaggers standing at the field’s edge, marking off each pass of the plane, are no longer used. Some of the flaggers used to be very pretty, very tanned, girls—sometimes in bikinis as the day got hotter. Pilot’s girlfriends, too!A computerized, highly accurate, GPS system allows pre-selecting the type of paths, width, and overlap. Pilot flies over one field edge, to mark the coordinates for the computer. A horizontal light bar, in front of the pilot, then shows him-his path and deviation from it, marching off the pre-selected sequence, as he makes pass after pass.Crop dusting pilots, especially OLD crop dusting pilots, are the highest skill level of any pilot—IMHO. They fly heavy, low and fast doing precision bombing and strafing runs--12 hours a day. Flying 6-15 feet off the deck, avoiding power lines, trees, and terrain. The skill level, stamina and judgment required to do this, for decades is much higher than a ‘Top-Gun’ pilot in combat…and I’ve known some those--too.Mark Minkema, head of TCA and John Green-who flies for Mark, sometimes—both have been doing this for a good 25 years. It’s a high-risk, occupation--that pays significantly more than military combat pilots.(A good pilot that stays busy-like 6-9 months out of the year, can gross $100-150K or more. They truly earn it.)TCA wanted to replace the existing, round tube, spray boom setup that came with this plane, by lengthening 2 old stainless steel, airfoil design booms, then lowering the booms, below the wing’s trailing edge—which prevents ‘blanking’ of the ailerons; which the round pipe setup did. It flew ‘funny’ with those round pipes.Layout, before fabrication:-discussed, measured, recorded on sketches, inside hose connection width, hanger mount points, old boom length. Lay out both booms on paper with the existing nipple locations, then layout and time the new foils and their spray nipples, making certain that these nipples are not at wing mount points.****TIP***-Layout on paper, first. Add up the measurements, several ways to make certain you don’t have math errors and that things will fit. -When making anything that has multiples of holes, pickets, etc.--on paper and on the metal layout--create a DATUM POINT (zero point) to measure off all the location points of the holes, pickets, etc.--from this DATUM point. (Simply measuring from one hole to the next to the next……ensures that you will have lots of location error, by the time you get to the other end.)     Use of DATUMS is one of the techniques used to create things that will fit.-Doing the above, takes some head-scratching and time. It pays--in avoiding and identifying problems, before the fact; and then helps the fab. part on the shop floor, move along quickly.-Identify the parts, as you cut them up, apart, etc.--to avoid confusion.http://www.weldingweb.com/attachment...1&d=1196040636Below are the finished, lengthened, 19’ booms. Added 78.5” to each, using formed stainless, 16 gauge, profile tubes from the original supplier. Boom profiles arrived, poorly packaged, being bent in 2 planes, plus twisted.There was no time, to re-order decent stock.This created finished booms, that are less than straight. I compensated, fiddled around, a bunch on fitup, to minimize this conumdrum. The original airfoil booms, were distorted, as well.The splicing was done on 1.5 x 3.0 aluminum channel and box tubing, set on top of the modular fixture’s steel frame. This provided a flat surface and a straight-edge reference for dealing with the warped pieces. The fitup focused on keeping the 2 hanger mounting points in line to each other and the inboard hose connection, parallel to the plane of the two mounting points--then, let the old and new parts, wander  and twist around as they may. This job isn’t perfection, it’s making functional bars that will fit.   http://www.weldingweb.com/attachment...1&d=1196040925The valves at the ends, are use for draining and flushing, after spraying. These are at the outer wing tips.Below is the new profile section, finished. Installed and seal welded 1/8” SS, machined pipe nipples, every 6 inches, timing their placement to the existing boom nipples. Hougen roto-broaches used to machine the holes for the nipples.Nipples were cut in half, i.d. & o.d. de-burred, cleaned, threads inspected, then located with a pin, to center them around the slug-cut holes, lightly clamped down, tacked in 2 places, then seal welded with SS TIG.http://www.weldingweb.com/attachment...1&d=1196041283Used remaining profile material to create wrap around doublers, over the 2 butt-welded splices of each boom. Welded the side gapping of these split-profile doublers—LONGITUDINALLY—not transversely, to translate stress along the side of the booms. The doubler ends are coated with urethane sealant, to prevent whatever fromgetting underneath them.Below is the  old, inboard hose connection end, spliced into the boom extension.http://www.weldingweb.com/attachment...1&d=1196041414(continued in Part 2) Attached ImagesBlackbird
Reply:closed windows.........eh......what happens when you gotta puke????All kidding aside, I have seen one of those up close, VERY HARDCORE planes.I HATE commercial flying, but I would go up in one of those any day.Very powerful from what I hear too....lots of times they pull up almost vertical after a run.Gotta use every bit of the field as possible which usually means some foiliage towards the end!!!!Miller blue star 2eLincoln 175
Reply:closed windows.........eh......what happens when you gotta puke???****I'm a commercial pilot, but I don't fly dusters--that's a young man's game. A pilot's guts, get very tough as time goes on, so we don't throw up.All kidding aside, I have seen one of those up close, VERY HARDCORE planes.I HATE commercial flying, but I would go up in one of those any day.*****there's only one seat in a Cat. You get in it, and train by doing! There are no Cat trainers that I've ever seen. Takes a pilot with some time, to jump into one.Very powerful from what I hear too....lots of times they pull up almost vertical after a run.***Yup!-the pull-ups are steep at each field end, then doing a 'wing-over', to partially or completely stall the plane, while rolling it, for this swooping, 180 degree turn back down to the next field path. It's dramatic to watch.Gotta use every bit of the field as possible which usually means some foiliage towards the end!!!![/I]****The field coverage overlap and pattern is preset on the ground, from the computer's menu, then the light bar marches off what path you are to fly for the pattern that you wish. Farmers need and expect full coverage.dave powelsonBlackbird
Reply:Or flaggers on the ground mark off the field as it's sprayed (they should wear a raincoat).KRS***************************************Lincoln AC225 stick welderLincoln HD100 WeldPak flux core wire feed welderThree of the cheapest grinders money can buy