C-130Hercules Posted June 19, 2017 Share Posted June 19, 2017 Hi everyone, After seeing this video, I have some questions. I know that the turboprops of the Herc are constant speed ones, meaning the pitch of the blades is adjusted in order to gain speed. In the video above, a Fat Albert is going through startup procedures. At 0:05 engine No.3 starts up and at 0:43 it seems like the engine is at idle speed. Then at 0:46 the engine increases its RPM which can be heard and seen. This startup procedure is repeated for the engines No.4, No.2 and No.1. When the video reaches 2:11, the engines somehow decrease their RPM. And with this RPM, the Fat Albert starts to taxi. Is there some kind of switch to increase and decrease the RPM of the engines? And what is the use of this increase and decrease of RPM? I hope to hear from someone soon. Kind regards, C-130Hercules Quote Link to comment Share on other sites More sharing options...
pjvr99 Posted June 19, 2017 Share Posted June 19, 2017 The engines have 2 speed settings, low speed ground idle and normal. Low speed is used to start and stabilize the engine, and also to do minimum torque calibration. Engines are generally held in low speed for taxi as it is easier to control oil temperature, than in normal. The #3 engine is sped up to normal to provide extra bleed for a quicker start on the other engines, and to provide air for the air conditioning packs. The APU provides +-40psi air pressure (unloaded) while an engine provides 80 to 100psi, although this is regulated to 70psi on some models Also use of low speed reduces fatigue on turbine assemblies Quote Link to comment Share on other sites More sharing options...
tinyclark Posted June 21, 2017 Share Posted June 21, 2017 Sorry, I didn't see anything but the airplane dress. Quote Link to comment Share on other sites More sharing options...
C-130Hercules Posted June 22, 2017 Author Share Posted June 22, 2017 Thanks for the explanation! Sounds a bit like a helicopter. Helicopters have ground and flight idle, rotor speed is effected by these settings. Quote Link to comment Share on other sites More sharing options...
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