In Flight
The Boston Globe has an on going project called The Big Picture that has put out some really amazing imagery over the years. They pic a theme and collect up impressive photos to go along, sometimes telling a story, other times just stunning us. Their most recent one is called In Flight and is all about aviation. There are a few standouts that caught my attention that I wanted to comment on…
These South Korean troops are performing one of my favorite maneuvers: tailgating a Chinook. Sure, you mostly see paratroopers jumping out of airplanes, but helicopters are just as common, especially for small teams. In Blackhawks and Hueys you sit side to side with your feet dangling out the door and when the jumpmaster gives the signal you have this little scoot-your-butt-and-shuffle maneuver to exit. Chinooks (and Pavelows for that matter) have ramps on the back that can be used to exit the aircraft in the same manner you tailgate a C-130 – just by walking off the back of the ramp. It’s quite a bit more fun! In the above picture, those two little bags on lines by the rotors are from the static lines that yanked the chutes open as the jumpers exited. Static line jumps aren’t like freefall jumps where you pull your chute. In this case a stowed bit of webbing clipped into a cable inside the aircraft get unraveled as you exit and the tension pulls on your chute, deploying it and you to safety.
Ah yes, the beautiful Russian Su-27. If you’ve seen photos of modern jet fighters, chances are you’ve seen ones like this with an apparent cloud clinging to the wings. This is caused by the compression of air (and moisture) as the flow over the wing is focused during high-G maneuvers. At higher altitudes there’s less air and generally less moisture so generally see this effect at lower altitudes. A similar effect can be seen when jets break the sound barrier, but that’s compression formed by shockwaves – a little different than this case (maneuver vs speed). Is this like contrails you see in airliners flying high? Nope, that’s mostly a temperature issue caused by the engine exhaust interacting with the cold of high altitude flight.
Here’s another common side effect of jets flying, but this time it’s all in the heat from the engine. What’s causing that distortion is subtle fluctuations in the temperature of the air is bending the light (refraction) in a noisy pattern. This is pretty much the same thing as mirage, though that’s caused by heat from the ground surface raising the temperature of the air.
Whoa? What’s up with THAT propeller? It looks like two attached to each other? Yep, that’s called a contra-rotating prop – both spin but in opposite directions at the same time. It’s a very effective design that eliminates the gyroscopic torque you’d get from a single spinning propeller and maximizes the ability of the prop to grab air and push/pull the aircraft through it. For decades the Russians fielded the Tu-95 bomber with four engines utilizing contra-rotating props against our best jet bombers. The Tu-95 still to this day is one of the fastest prop-driven aircraft and set records for endurance.
The angels arrive. Here a Medevac (Medical Evacuation) chopper is arriving to extract the wounded after an IED attack in A’stan. The Army has a really good system for troops to call for these kinds of missions called a “Nine Line”, which consists of nine questions that need to be answered back to the incoming chopper. It’s something everyone trains on so that even the most inexperienced Private can call in help. As these guys come barreling in, the Nine Line lets them know how many are injured, how badly, is the landing zone safe or can they expect to be shot at, etc. It’s a great system that combined with the bravery of these aircrews no doubt is saving lives on a regular basis.