Why do B-52s' leave huge clouds of black smoke when they takeoff?

Question

I looked at several pictures of them and they all show clouds of black smoke coming out of the engines.

Answer 1

The "old school" J-57 engines on the early model B52's used water injection for added thrust. It would make a very dark smokey trail behind the aircraft as it took off. They were replaced on the G and H model.

Answer 2

Because the eight engines are very "old tech" and inefficient.  If you look at pictures of most early jet aircraft, both large and small, you will see that they are very smoky.  Modern engines burn fuel more efficiently and emit a far smaller amount of unburned hydrocarbons.

When the B-52 was built the military was paying almost nothing for fuel and environmental concerns were minimal.  With fuel costing much larger amounts, and with today's environmental concerns the B-52 is a very dirty and expensive airplane.  Unfortunately, it's the best thing we have for its purpose and there is not likely to be a direct replacement any time soon (if ever).

Answer 3

Turbojet engines burn a fuel that is essentially kerosene, and they all make black soot at full throttle and low airspeeds.  Even the most modern jet airliners leave a brown haze behind them on takeoff; it's just not as noticeable as it is on the old B-52.

The B-52s were built with a total of eight (8) turbojet engines because of the great power requirement and the fact that those were the most powerful engines available at the time.  And those engines are pure turbojet:  no bypass (turbofan) percentage at all.  So they make a big plume of soot compared to an Airbus or a Boeing airliner of today.

Some of the B-52s have been re-engined with newer turbofans, but the original engines gave the ships performance similar to that of the fighter aircraft of the day, and to keep that, they had to keep the old engines.

Answer 4

Airplanes require lots of energy to get going, and to take off requires huge amounts of fuel, so there is alot being burned in a short amount of time.  Once its up in the air, the fuel consumption levels out, and the air to fuel mix is better.  thats why the smoke disappears at speed and while its in flight.