I just have a couple of questions that i never got around to asking.What does bypass mean? like when they say its a high bypass engineWhat is engine bleed and apu bleed?How do i calculate the thrust to weight ratio?What is the difference between indicated airspeed, groundspeed, and true airspeed?does a pressure altimeter show alt over MSL?Whats is the difference between magnetic heading, true north heading, track heading, and compass heading?ThanksAdam

Type these questions as words into your web browsers search function; such as "high bypass engine". You'll get many more complete answers & diagrams than possible here. I do this a lot; especially when I don't have all the answers for the questions that come up here, or want a backup to what I think is correct.L.Adamson

I'll give this my best shot, should at least point you in the right direction.Bypass is a term used when refering to turbofan engines. After passing the fan the air flow is split into 2 parts, one part goes into the core engine for cumbustion, the other part goes through a by-pass duct surrounding the core. A high by-pass engine means that very little air flow goes to the core, so most of the thrust is being provided by the fan section.Engine Bleed refers to air taken from the compressor, allowing higher mass flow at the first stages during low power settings. This is done in an attempt to prevent compressor stalling and surging. This air is nalso used for pressurization and environmental systems. APU bleed I'm not very familiar with but I believe it's used for environmental systems and engine starting.Thrust to Weight Ratio I believe is normally the engine's installed thrust divided by the Max Gross Weight of the aircraft.Indicated Airspeed is the speed read of the Airspeed indicator, it does not take into account calibration, pressure, and temperature errors.Groundspeed is simply the speed travelled over the ground.True airspeed is Equivalent Airspeed corrected for temperature errors and is an indication of the actual speed travelled through the atmosphere.Pressure altitude displays altitude in MSL assuming standard atmospheric pressure.Magnetic Heading is True Heading corrected for magnetic variation.True Heading is a heading relative to True North in order to follow a predetermined track.Track Heading? do you mean True Track? If so it's simply the bearing relative to true north from one point to another.Compass Heading is what you actually fly in the aircraft, it's magnetic heading corrected for magnetic interference. Each aircraft has a compass correction card. The corrections determined using an annual compass swing, where the aircraft is pointed in certain directions on the ground and the compass reading is recorded.Hope this was helpful, anyone who sees any errors feel free to jump in.

thanks for the repliesadam