Originally Posted by HN39
If you are serious, the concept is quite simple.
Well, I thought so, as I said earlier. But unfortunately my simple explanation doesn't appear to satisfy everyone (although I suspect you know it's right, even if Guppy can't tell).
Originally Posted by HN39
In forward thrust mode, the net propulsive thrust of a jet engine is gross thrust (aka 'nozzle thrust') minus intake momentum drag (aka 'ram drag'). In reverse, for the same fuel flow, N1, N2, etc., the engine air flow and hence intake momentum drag is unchanged and part of the 'nozzle thrust' is deflected sideways and forward. On modern high bypass-ratio engines, only the bypass air is deflected, the gas generator exhaust is not.
And how does this square with
Originally Posted by PBL
...if one does look in textbooks, such as John D. Anderson's Introduction to Flight (which is ubiquitous), one will find (courtesy of Rolls-Royce PLC) in Figure 9.19, p720, a division of the x-axis components produced by a jet engine in normal thrust-producing mode: in sequence from front to back,
Compressor produces about 19,049 lb forward
Diffuser produces 2186 lb forward
Combustion chamber produces 34,182 lb forward
Turbine produces 41,091 lb rearward
Exhaust unit/nozzle produces 5587 lb rearward
?
Answer: it doesn't. Some of these values are changed during use of reverse thrust. However, you and Guppy seem to suggest that some things are unchanged. So let me ask more precisely: which of these values do you think will remain unchanged, and which stay the same, if said engine is in "thrust reverse" configuration?
ChitterneFlyer,
this isn't about semantics.
PBL