posted on Jul, 15 2013 @ 05:08 PM
reply to post by AndyMayhew
New and more efficient engines are being invented all the time. Even now Boeing and Airbus aret aking orders for their next generation models of the
A320 and 737 families which are to be powered by the latest tech GTF (Geared Turbo Fan) engines. These are called the A320neo and 737MAX to
distinguish them from the previous models.
The thing here is that because these engines are designed to use less fuel in order to produce a greater or equal amount of thrust, more of the power
has to be drawn from the ambient air, which in turn means more water, which means thicker contrails. On the plus side, the exhaust is mostly air, from
which the contrails condense out.
It is for example why the 737-200 produced fewer, and much smaller, trails from its JT8D engines than the current equivalent 737-700 does from its
Set against the fewer trails, the 737-200 was much noisier and the jet efflux was mainly made up of jet exhaust byproducts and pollutants plus the air
drawn through for combustion.
With the CFM 56 however, the exhaust is five parts air to one part combustion exhaust (5:1 Bypass Ratio). On the PW1000GTF as selected for the next
gen A320 (the current version of which also uses the aforementioned CFM-56) This bypass ratio is increased to 12:1.
So modern engines are far cleaner than previous jets, but this is also why they produce more trails. Given that you cant have your cake and eat it, as
the saying goes, I am happier that jet planes made the switch
edit on 15-7-2013 by waynos because: (no reason given)