After opening the throttle and pulling back on the yoke, the plane bounced down the runway and suddenly the ground was falling away and the houses and cars below became toys.
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WHEN phone footage came to light last year of a stripper opening the throttle during the take-off of a commercial jet operated by Aerolíneas Argentina, the public outcry was predictably fierce.
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It read: "All flights cancelled, flying tomorrow. Duncan."Barnes et al., p. 16. Thain told the station engineer, Bill Black, about the problem with the boost surging in the port engine, and Black suggested that since opening the throttle more slowly had not worked, the only option was to hold the plane overnight for retuning.
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Thain was anxious to stay on schedule and suggested opening the throttle even more slowly would suffice. This would mean that the plane would not achieve take-off velocity until further down the runway, but with the runway almost long, he believed this would not be a problem. The passengers were called back to the plane 15 minutes after leaving it.Morrin, p. 103.
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When opening the throttle, acceleration enrichment (accelerationsupprikning in Swedish) occurs and when closing the throttle deceleration emaciation (decelartionsavmagring in Swedish) occurs. During a cold start and warm up, before lambda correction is activated, coolant temperature dependable fuel enrichment occurs. With a warm engine and normal battery voltage the duration of injection varies between 2,5 ms at idle and approx. 18 – 20 ms at full torque.
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Below 4000rpm the duct closes down about one-third of the intake area. The result is amazing: when suddenly opening the throttle, the new 900 twin pulls stronger than ever without any hesitation. And with the help of the injection system even on high mountain roads (up to 3000 meters!) the fuel mixture is always adjusted properly. Riders who use their bike often on higher altitude, will fully understand and appreciate these benefits.
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The throttle cable attaches to the curved, black portion on the left. The copper-coloured coil visible next to this returns the throttle to its idle (closed) position when the pedal is released. When the driver presses on the accelerator pedal, the throttle plate rotates within the throttle body, opening the throttle passage to allow more air into the intake manifold, immediately drawn inside by its vacuum. Usually a mass airflow sensor measures this change and communicates it to the ECU.
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The latter monitors engine speed by counting electrical pulses from the ignition system or from a magnetic pickup and, depending on the speed, makes small adjustments to the amount of current applied to the motor. If the engine starts to slow down relative to the desired speed, the current will be increased, the motor will develop more torque, pulling against the return spring and opening the throttle. Should the engine run too fast, the governor will reduce the current being applied to the motor, causing the return spring to pull back and close the throttle.
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Liquid gasoline, being denser than air, is slower than air to react to a force applied to it. When the throttle is rapidly opened, airflow through the carburetor increases immediately, faster than the fuel flow rate can increase. Also the air pressure in the manifold increases, decreasing the evaporation of the fuel, so less fuel vapour is sucked into the engine. This transient oversupply of air relative to the fuel causes a lean mixture, which makes the engine misfire (or "stumble")—an effect opposite to that which was demanded by opening the throttle.
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This flow rate was entirely independent of fuel level, but did remain approximately proportional to the mass airflow. The Fish carburettor was also sensitive to mass airflow, rather than volume airflow, making it self-compensating for changes due to temperature or altitude. A second problem with the conventional carburettor was its good performance in steady conditions, but poor progression: its dynamic ability to respond, such as when suddenly opening the throttle. This could give 'flat spots' in performance, or required great additional complexity to the carburettor such as multiple chokes, emulsion tubes and accelerator pumps.
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During the Battles of France and Britain, the German fighters had fuel injected engines and therefore did not suffer from this problem as the injection pumps kept the fuel at a constant pressure. The German pilots could exploit this by pitching steeply forward while opening the throttle, a manoeuvre that the pursuing British would be unable to emulate. The British countermeasure, a half roll so the aircraft would only be subjected to positive G as it followed German aircraft into a dive, could take enough time to let the enemy escape.
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Another common application is the control of the throttle of an internal combustion engine in conjunction with an electronic governor. In this usage, the motor works against a return spring to move the throttle in accordance with the output of the governor. The latter monitors engine speed by counting electrical pulses from the ignition system or from a magnetic pickup and, depending on the speed, makes small adjustments to the amount of current applied to the motor. If the engine starts to slow down relative to the desired speed, the current will be increased, the motor will develop more torque, pulling against the return spring and opening the throttle.
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Longitudinal mounting also means that the torque reaction will twist the motorcycle to one side (such as on sharp acceleration/deceleration or when opening the throttle in neutral) instead of shifting the weight balance between the front and rear wheels. However, many modern motorcycles reduce this effect by rotating flywheels or alternators in the opposite direction to that of the crankshaft. One of the first motorcycles with a longitudinally-mounted flat-twin engine was the 1916 ABC, which was built in the United Kingdom. To accommodate chain drive, the ABC used a bevel drive at the gearbox to change the direction of the drive through ninety degrees.
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The stator element of the torque converter has two blade positions, controlled by the driver via the accelerator pedal to offer a 'passing gear' and extra response at any speed from heavy throttle application. In normal driving the stator blades are arranged at 'cruise' angle, with improved efficiency and response at light throttle. Opening the throttle changes the angle of the stator vanes hydraulically to 'performance angle', which permits the converter to achieve stall about 1000 rpm higher than in 'cruise'. In this situation oil is redirected to strike the next- lowest drive turbine, which effectively lowers the drive ratio, and allows engine speed to flare to a speed where output is greatest.
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This control system included interlocks to close the throttle valve at the end of trip and to prevent opening the throttle again until the winding engine was reversed. The control system also incorporated a governor to control the speed of the hoist and indicator wheels to show the hoist operator the positions of the skips in the mine shaft. The hoist controllers for modern electric mining hoists have long included such features as automatic starting of the hoist when the weight of coal or ore in the skip reaches a set point, automatic acceleration of the hoist to full speed and automatic deceleration at the end of travel.H.K. Burch and M.A. Witting, Automatic Operation of Mine Hoists, in Trans. Amer. Inst.
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If the airflow into the engine is increased – by opening the throttle plate, or by allowing the engine revolutions to rise with the throttle plate at a constant setting – the pressure drop in the venturi increases, the pressure above the piston falls, and the piston is sucked upward, increasing the size of the venturi, until the pressure drop in the venturi returns to its nominal level. Similarly, if the airflow into the engine is reduced, the piston will fall. The result is that the pressure drop in the venturi remains the same regardless of the speed of the airflow – hence the name "constant depression" for carburettors operating on this principle – but the piston rises and falls according to the speed of the airflow. Since the position of the piston controls the position of the needle in the jet, and thus the open area of the jet, while the depression in the venturi sucking fuel out of the jet remains constant, the rate of fuel delivery is always a definite function of the rate of air delivery.
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