At its Olney Texas, United States manufacturing facilities, Air Tractor produces a line of aircraft that includes 400, 500, 600 and 800-gallon capacity airplanes powered by Pratt & Whitney Canada PT6 turboprop engines. The airplanes are used for agricultural aerial application, firefighting, narcotic crop eradication, fuel hauling, fighting locust plagues, and cleaning oil spills in coastal waters. From North, South and Central America, to Australia, Indonesia and China to Spain, Italy, Croatia and Africa, Air Tractor aircraft can be found working in more than 30 countries around the world and are supported by a global network of Air Tractor dealers. Learn more at airtractor.com.
Considering Ag flying , is low level and very unforgiving. Why not introduce Fly by Wire, where the computer then tames the riskier parts of flight controls. eg , reduce the risk of uncoordinated input and other risky parts(full load g limits) of the flight regime
My !995 Bush Pilots CFi taught me turnbacks 2 kinds. Teardrop and the most dangerous Hook Turn or Question Mark turn. If power we did only the Teardrop Turnback only. The Hook Turnback was done at 45 bank only and over the Vglide speed and if 2k feet away from were we wanted to finish it- otherwuse it will be too tight and dangerous as F. We used turnback training for GRM Turnbacks, Box Canyon Turnbacks and EFATO Turnbacks with partial or no power emergencies. Too tight Hook Turnbacks are too dangerous, if power is better to do the Teardrop Turnback.
'As the hopper empties, the CG moves aft, and the elevator effectiveness is reduced'. (Video at approx 41:03) Is this the case? I thought that an aft CG increases pitch sensitivity? Can anyone help me with this?
"The belly is an ungrateful wretch, it never remembers past favors, it always wants more tomorrow." - Aleksandr Solzhenitsyn Think of it as job security. Feeding the World, and please don't stop.
Doing my primary training I specifically sought out a flight school that would allow me to do spins during my primary training. I still remember seeing the intersection of I-95 and I-40 rotating in my windshield. Great fun and I learned a lot doing this. My instructor kept telling me to ask myself what would I do that would make me bust my a$$ every time I strap a plane on. Works for everything.
This is a far simpler issue than anyone want's to believe. *The wing stalls at its critical angle of attack.* At the critical angle of attack, airflow separates from the upper surface of the wing. This reduces lift substantially as the critical angle is exceeded. Any additional angle of attack will result is exponentially less lift and more drag beyond the critical angle. The critical angle of attack is ~ 15 degrees for most common airfoils. (Although Reynolds number, camber, and leading edge shape play a role in the exact angle of attack which the airflow will separate). It will usually happen around 15 degrees for normal airfoils found on most GA aircraft. (Sources: NACA and Eppler). The wing is mounted to the fuselage at a fixed angle of incidence. So is the Horizontal stabilizer. They are both fixed to the fuselage in relation to each other, having the same or small difference in their respective incidence angles. The elevator sets the wings angle of attack while airborne. The wings angle of attack cannot pitch up significantly without up-elevator deflection. (Although vertical gusts can momentarily increase the angle of attack). *UNLESS the aircraft is loaded with a center of gravity at or behind the Neutral point. In which case the aft mass centroid will overpower the horizontal stabilizers lift, depressing the tail, and causing a divergent pitch-up. (This is know as relaxed static stability and is a stability feature of the F-16 and Wright 1903 flyer). So now we have established that a stall requires trimming the wing to +15 degrees AoA. And this can only happen with up-elevator input applied from cruise or any normal level flight or climbing/descending or turning maneuver. *Except when going straight up. Where the aircraft can be brought to a stop and backed downward in a tail slide without deflecting the elevator substantially. (Which again takes elevator to pitch to that angle in the first place). So to reiterate, in order to stall the wing; The wing must pitch to its critical angle of attack. In order to reach that angle or attack, barring extreme vertical maneuvers, the elevator must be deflected to trim the wing to that angle. If you slow the aircraft down to its stall speed in level, horizontal flight. This is also the critical angle of attack. Notice the nose high attitude? Why is it holding this higher nose attitude in slow flight? Notice your stick position. You are easing back on the controls to transition into and maintain slow flight. If you ease the stick forward you will descend and pick up speed. To fly slow, it requires up-elevator, which requires aft-stick. You say "no I'm not! Look, hands free!" ~ Yes, but that's because you trimmed out your stick forces. Allowing the elevator to deflect upward due to the trim tab being deflection downward by the trim controls. This upward elevator deflection trims the aircraft to the slow speed, which is near stall; near its critical angle of attack. An airfoil generates lift due to meeting the airflow at an angle of attack. There is a close relationship to angle of attack, and lift coefficient. The lift-curve slope of any given airfoil is simply CL/a. That is increment of Lift coefficient over angle. It is nearly a straight line extending up to stall. If you want more lift at a given speed, you need more angle of attack. If you want to fly upside down, you need negative angle of attack. It cannot be done any other way. The theoretical CL/a is 2pi Radians, (1 Rad is 57.3 degrees) and stalling angle of attack of conventional airfoils is 15degrees. (0.2618 radians). This results in an approximate Lift coefficient of 1.645. (Right in the range of most conventional airfoils). The NACA 23012 as found on many notable aircraft, has a well tested and verified CLmax of 1.64. Lift coefficient is increased by increasing the angle of attack. And lift is simply lift coefficient multiplied by free-stream dynamic pressure (q), multiplied by wing area.(At 60mph, is 88ft/sec. Where q= 9.2033 m) An aircraft having a wing loading of 15lb/ft^2 will begin to fly at this speed at an angle of attack of 14.83 degrees: Nearly stalled. (Probably stalled with any disturbances). An aircraft on the ground in landing attitude is not typically stalled. Even though pilots call it a "full stall landing" this is not entire true. Most taildragger/conventional gear aircraft sit at a 10-11 degree deck angle. With another 2-3 degrees of wing incidence. This equates to less than 15 degrees. Therefore it meets the oncoming air below its critical angle of attack while taxiing, three-point landing, or beginning the takeoff roll. The airflow is still attached ~ It's simply not flying yet, because dynamic pressure is too low to generate sufficient lift to carry the weight of the aircraft at this low speed. But the wing is not stalled! This is knowable and provable by the fact you can hold the tail low to generate lift, allowing the airplane to get light on the wheels at a much lower speed than is required for liftoff. This technique is used for soft field takeoffs. So, therefore the wing is not stalled as it still generates lift due to angle of attack and "q" while moving slowly on the ground. It has not exceeded its critical angle of attack. And it cannot, because the landing gear geometry where the tailwheel keeps the wings attitude below the critical angle of attack. Only once airborne, with sufficient back-stick, or up-elevator trim, and maybe prop-wash contributing to tail effectiveness, can you stall the airplane. By rotating to an angle of attack slightly higher than the ground angle of attack after liftoff, then the wing will stall. This fundamental principal applies everywhere and at all times. The elevator stalls the wing because the elevator is what trims the wing to it's angle of attack. And the elevator is connected to the stick, which must be displaced aft to deflect the elevator. Therefore, by not pulling aft, you can prevent the wing from stalling. The extreme opposite case is stalls can happen at any airspeed and attitude. Including while diving straight down at Vne. A stall can be induced with an aft-deflection of the stick. This is how you initiate a snap roll. Pull, stall, rudder, snap. At an airspeed well above stall. This is evident at any airshow or aerobatic contest. Where snap-rolls and tumbles are entered at speed above the stall speed. Often at Va (maximum maneuvering) speed.
Excelente Instructivo para principiantes y veteranos. Sería interesante poder escuchar este video en Español, dado qué hay una cantidad de demanda de estas maravillosas aeronaves en Latinoamérica. Gracias Air Tractor.
Great information for GA pilots and in particular the issue of the so called Impossible Turn, the 180 degree turn back to a departure runway when you experience an engine failure. This turn invariably becomes a steep turn which leads usually to a stall/spin . If you ever practiced these manouvers like we do in Canada , believe me you would be wary of doing it in an emergency.
I thought Airtractors were not suitable for dropping the whole payload at once, since some of them have already fallen apart doing so. Maybe this version of the AT is reinforced and designed for this application
Used here in Tenterfield - NSW Terra Australis - over the last 2 weeks we put through 60,000 litres per day to control fires here. Fortunately the rain came at the right time. Admirable performance!
As a mechanical engineer from 'down under'(Australia) it's always excellent ot see dedication, skill and experience on show in the 'good ole ... ' that gets such flack at times. I can see why you've been chief pilot for so long - as they say, there are no bold pilots that endure to become old pilots. Nice combination of technical smarts and practical experience.
Flight reviews indicate an increasing habit of RUDDER initiated turns instead of AILERONS, and then when the bank is too steep, AILERONS are being used to lift the wing, and inducing a STALL/SPIN. CURE: Large BALL/SLIP indicator at top center of panel & continuous education. Cheers 60yr CFI R bud Fuchs
I'm a sailor. I want to learn to fly. The part about "wind aweness" really hit home. I also commuted in Los Angeles for years on a motorcycle, splitting lanes when cars were stopped or moving slowly during rush hour traffic. Without situational awareness, you crash. It's that simple. Motorcyle crashes are similar to plane crashes. People usually get hurt or they die. One of the most counter-intuitive things I learned riding through traffic and especially when splitting lanes, is to NOT look at the CARS surrounding and manuvering around me. Instead, focus on the SPACES BETWEEN CARS. Then, it's a matter of surfing and gliding and riding through those spaces. Flying looks a lot like riding a motorcyle to me in that regard - but in 3 dimensions. Like with motorcycles, certain mechanical failures can cause you to crash in aircraft, but the main root causes of GA accidents are on the pilot - in roughly this order: Lack of skill / current proficiency Recklessness / showing off / screwing around / trying to meet a schedule Complacency / lack of situational monitoring and awareness VFR into IMC Running out of gas A lot of the above are bundled into CFIT statistics from what I've seen. CFITing is like crashing your motorcycle into a telephone pole. There's no reason it should EVER happen. Telephone poles and the ground do not viciously jump out in front of motorcylists and pilots. Airplanes do not suddenly stall and spin for no reason. Motorcylists and pilots lose situational awareness slam themselves into immovable objects because of poor situational awareness, complacency, and/or reckless behavior. ALL of that is under the direct control of the pilot. All of it. The thing about riding motorcyles in heavy traffic is that the rider has zero control over the thousands of cars they'll interact with on their communte. Pilots have ATC looking over their shoulders and watching their backs, and mid-air colisions still happen all the time. Again - situational awareness. Mid airs should never happen. Pilots need to pay attention at all times to their environment. On a motorcycle the slightest lapse in attention or judgement can lead to an immediate, catastrophic loss of control. In that regard, aircraft are more forgiving,because most of the time you're surrounded by thousands of feet of air you have to travel through before you're gonna slam into anything. On a bike, you're never more than a fraction of a second away from slamming into something very hard and unforgiving. When I read about GA being 1.5 times more dangerous than riding a motorcyle on the street, I think the risk is acceptable, because I rode a motorcycle daily for over 4 years, and racked up thousands of hours over my lifetime on them, and never sustained any serious injuries. Most of the falls I had came early, and were totally my fault - being a reckless teenager and all. I'm a wiser older man now, and am looking forward to my flight training, and recreational sport flying. It looks like it's challenging, beautiful, and a heel of a lot of fun and safe - as long as you know and respect your own limits and those of your aircraft, and pay attention to the weather and your immediate environment.
