Another question about the downed Apache.

mangeorge: Helicopters fly differently from airplanes. As you know, the higher you go the less air there is to go over your wings. In an airplane you need to go faster the higher you go to get the same amount of lift. This is a good thing, since pilots always want more speed. In a helicopter you have to slow down the higher you go because of retreating blade stall. That is, the faster you go the less forward airspeed you have on the retreating blade and the closer it is to stall. It works the same at sea level of course, but the air is thicker there so you can fly faster than at altitude. That’s one reason why helicopters tend to fly lower than fixed-wings.

Another reason for flying low is the mission. Hovering is all well and good, but it doesn’t do a lot for you unless you’re close to the ground. Helicopters were designed for missions close to the ground, and so that’s where they fly. They also hover better in ground effect than out, much as an airplane flies better IGE.

Military helicopters have an even tougher role. People shoot at them. Unlike a fighter jet that can operate at 40,000 feet, the helicopter can’t rely on altitude to escape ground fire. Helicopters are also relatively slow (see retreating blade stall), so they can’t speed away from danger. What they can do to avoid enemy fire is to fly as low to the ground as possible. By flying low they can put hills, trees, structures, etc. between themselves and the people shooting at them. I fly around at 400 or 500 feet AGL, except when passing off the coast by LAX when I get down to about 90 feet. Even these lofty heights are considered low by fixed-wing pilots who cruise around the neighbourhood at 2,500 feet and make trips at 9,500 feet (more or less, depending on the pilot’s preferences, decisions, weather, etc., etc.). No one is shooting at me. Military helicopter pilots routinely fly “nap of the earth”, which translates to “mighty bloody low”. The good news is that they can put obstructions between themselves and the shooters. The bad news is that they’re closer to the shooters to begin with, and NOE can be dangerous in itself.

So it’s not a “macho thing” at all. It’s just that that’s the nature of the machine. Besides, it’s fun to fly low!

Okay, I might as well get them out of the way…

“Why do helicopters fly so low?”
“Because helicopter pilots get nosebleeds above 500 feet.”

“Helicopters don’t fly. They’re so ugly, the Earth repels them.”

“Helicopters don’t fly. They beat the air into submission.”

“Helicopters are 10,000 seperate parts flying in close formation with the intent of doing the pilot harm.”

Thanks, Johnny L.A.. In fact I’ve flown (ridden :)) in Hueys a few times when I was in Vietnam, in the Navy. Great fun, I must say. I even got to sit in the little seat by the door once, although those lousy Marines wouldn’t let me play with the M60.
Anyway, it seemed that when flying over open terrain, we kept relatively high. But over jungle, which was most of the time, we flew close to the treetops. Slow? My ass! :stuck_out_tongue:
Oh, and it was a macho thing.
Peace,
mangeorge