Checkboard - When I was composing my own
briefer response
, I prefaced it by asking DECU whether he was asking about jets' efficiency in comparison to [1] itself at lo altitude, or [2] a propellor (at hi altitude, presumably).
I used as a quick reference for the latter, the afore-mentrioned
MECHANICS of FLIGHT, which covered the propellor comparison much as you did (p. 133-135). On rereading DECU's question, it seemed pretty clear to me he was asking about the hi-lo jet comparison, so I ditched it all, save the mention of the text, and then went on to address the efficiency that most pilots care about when they ask about the engine - nm/lb rather than sfc #'s.
One small quibble - Thrust is a force (massxacceleration). When applying the T=mv formula, this yeids the
momentum given to a particular mass of air, more properly stated in basic units of measurement as = MxL/T. The thrust/force would be derived from the rate at which momentum is given to masses air, or MxL/T
/T(again), or mass x acceleration.
N'est-ce pas? You are obviously much more deeply schooled in this stuff than I, hence my repeated retreat behind KISS principles.
Cheers, Atlas
[This message has been edited by Atlas (edited 22 June 2000).]