It differs with every machine. Large military helicopters generally have longest range and near highest speeds.
it's altitude should be whatever is economical for that flight
Helicopters typically fly at speeds ranging from 90 to 160 miles per hour, depending on the model and purpose. Some larger helicopters, like military or transport helicopters, can achieve speeds up to 200 miles per hour. However, the cruising speed is often around 120 miles per hour for many civilian helicopters. Factors such as payload, altitude, and weather can also affect a helicopter's speed.
Helicopters are not very well suited to high altitude flight. By their very nature helicopters less suited for high altitudes than airplanes or balloons. Additionally, since the most common usages of helicopters deals in short hops or other low-altitude duties, modern helicopters aren't designed with high altitude flight in mind. The stratosphere is generally agreed to start at about 30,000 feet altitude. While this is pretty near to the helicopter altitude record (in 2005 an Ecureuil/AStar AS 350 B3 helicopter landed on Mount Everest (29,035 feet)) This is far higher than the ceiling of the average helicopter (10 to 12,000 feet).
There is a significant difference in speed and range between helicopters. What type are you asking about?
An inverse relationship.
Radar is an object-detection system that uses radio waves to determine the range, altitude, direction, or speed of objects
Helicopters fly somewhat close to the ground. They fly near the troposphere. They fly at a lower altitude than planes.
It depends on the aircraft's altitude. The speed of sound is decreasing as altitude increases, thus an airplane flying at the speed of sound at 1000 feet will be traveling as fast as 1200 kilometers per hour, while one flying at 30000 feet will be moving way slower, in the 800 kph range.
how does is wind speed affected by altitude
32.8 ft
The air gets thinner as altitude increases, which in turn decreases the amount of lift an aircraft can get. The air in the stratosphere is far too thing for helicopters and most planes.
You measure forward air speed in the same way you do in any aircraft.