What does the " heavy "...

[onepersonsopinion]

Originally Posted by GT_ATCfan

As a clarification, it is not "smoke" coming out of the engines what you are seeing in some of these pictures. It is in fact water vapor that condenses and/or crystallizes becoming visible. The formations that result are generally referred to as contrails. The engines exhaust gases and particulate matter (PM, or soot) that result from the combustion of air and fuel. These combustion products are visible, for example, in older aircraft that are equipped with gas-guzzling turbojet engines. The smoke is clearly black.

The use of the term "smoke" in my post was made purely in reference to n250jg's comment regarding "smoke trails." I realize that they are not "smoke," but used that terms to maintain consistency in this thread.

I happen to be have an acquaintance with Mr. Bernoulli, and while I have not run my own direct experiments, I find the contrail systems developing behind today's high BPR propulsion systems extraordinary, to say the least. Has anyone been able to recreate these enormous "cloud-like" systems in a lab?

[ColtsATC]

And to clarify, it's aircraft capable of having a takeoff weight of 255,000 lbs or more. Hence why a KC-135 is a heavy, but a C-130 isn't. Close is size, but KC-135 carries ALOT of fuel when fully loaded.

[SayAltitude]

Originally Posted by onepersonsopinion

The use of the term "smoke" in my post was made purely in reference to n250jg's comment regarding "smoke trails." I realize that they are not "smoke," but used that terms to maintain consistency in this thread.

I happen to be have an acquaintance with Mr. Bernoulli, and while I have not run my own direct experiments, I find the contrail systems developing behind today's high BPR propulsion systems extraordinary, to say the least. Has anyone been able to recreate these enormous "cloud-like" systems in a lab?

A jet engine sucks in air and sends it through the turbine to create thrust. On an older jet engine (turbojet - think old school 727) that was all you got as far as thrust was concerned. Therefore, all your air getting pushed out the back got sent through the combustion section of the turbine and therefore contained very little water that would condense in the form of a contrail. You still got them, but they were weak and dissappaited fairly quickly. High Bypass Turbofans derive roughly 80% of their thrust from "Bypass Air" that never even touches the combustion section of the turbine. It's far more efficient and Bypass Air is more likely to hold more water - producing a stronger, longer lasting contrail on the back side.

[Roddy Piper]

Originally Posted by ColtsATC

And to clarify, it's aircraft capable of having a takeoff weight of 255,000 lbs or more. Hence why a KC-135 is a heavy, but a C-130 isn't. Close is size, but KC-135 carries ALOT of fuel when fully loaded.

that's correct. max gross takeoff weight is more than 255K lbs. doesn't matter what the actual weight is when taking off.