Sequence of the first launch of the first Martian helicopter Ingenuity (scheduled for April):
- The helicopter will undock from the rover. The rover drives off.
- The helicopter takes off 13 cm, but with a cable connection to the rover.
- The wire is fired off with a pyro-charge.
- The helicopter takes off up to 3 meters (climb speed – 1 m per second).
- 30 seconds hovering (helicopter power reserve 90 seconds).
The Ingenuity helicopter will carry a piece of fabric from the Wright Brothers Flyer 1. Ingenuity is not the first NASA spacecraft to carry a piece of Flyer 1 off Earth. Another piece flew to the moon and back aboard Apollo 11.
Under the cut – synopsis 2019 video report on Ingenuity and a conversation with the developers.
First powered flight over another planet
In 1985, the USSR used flying helium balloons to explore Venus. As part of the Vega mission, two probes transmitted data from an altitude of 54 km for more than 46 hours.
Flight conditions on Mars
Flying a helicopter in the Martian atmosphere is like flying 30 kilometers above the Earth. Not a single helicopter has taken off more than 12 km, and the record for aircraft is 26 km.
The density of the atmosphere on Mars is 1% of the density of air at the Earth’s surface. On Earth, a cubic meter of air weighs 1.205 kg, the same volume on Mars will weigh somewhere around 15-18 grams.
You need a powerful stream to fly. The simplest solution is to rotate the blades faster.
The density of the atmosphere on Mars is 1% of the earth’s.
The gravity on Mars is 38% of that on Earth.
The speed of sound on Earth is 340 m / s
Sound speed on Mars – about 240 m / s
The rotation speed of Ingenuity blades will be 2300-2900 rpm (40-50 rps).
The rotation speed of the blades of the earth’s helicopter is 500 revolutions per minute (9.5 revolutions per second.
There is a limitation: it is impossible for the tips of the helicopter blades to exceed the speed of sound, because of the shock waves, non-standard aerodynamics and transonic flows occur. In the calculations, the blade speed is 70% of the speed of sound.
The weight of the helicopter is 1.7 kg.
Propellers and blades
The Ingenuity helicopter has two blades made of foam board covered with a layer of carbon fiber. Each blade weighs 35 g. The blades rotate 40 revolutions per second during flight. The helicopter is designed for 90 seconds of flight.
We did not take a quadrocopter as a basis, because the blades of the quadcopter must be so long that the aircraft would not fit on the Rover.
The helicopter is made in a coaxial scheme with two propellers 1.2 meters in diameter, which will allow it to float in the air. Two coaxial propellers are the simplest solution because they are more effective at generating lift when they are on top of each other.
Coaxial scheme – a scheme for constructing a helicopter (or aircraft propellers), in which a pair of parallel propellers rotates in opposite directions around a common geometric axis.
On Mars, grains of sand are carried by the wind, and they can accumulate a triboelectric charge. The discharge can ionize gases near the surface, which could affect the chemistry of the Martian atmosphere. If discharges occur at night, sparks can be seen.
Triboelectric effect – the appearance of electric charges in a material due to friction. It is a type of contact electrification in which some materials become electrically charged after they come into frictional contact with another material.
The Copp-Etchells effect is one of the special cases of triboluminescence (see also Triboluminescence). The term comes from the Greek τρίβειν – “friction” and the Latin lumen – “light”. Light is generated due to the breaking of chemical bonds in a material during its separation, rupture, crushing, rubbing, or other similar mechanical action.
One American journalist noticed an unusual glow that occurs when a helicopter lands or takes off in the desert due to the friction of the helicopter blades against particles of sand and dust in the air. The phenomenon was named after two American soldiers – Kopp and Etchels – who died in July 2009 in Afghanistan.
Simulator of the rarefied atmosphere and gravity of Mars on Earth
Building 150 – Twenty-Five-Foot Space Simulator
there is Twenty-Five-Foot Space Simulator, there you can recreate any pressure and check the aerodynamic component, but you cannot simulate reduced gravity.
Twenty-Five-Foot Space Simulator
To test the helicopter, they used gravity unloading. Those. pulled the helicopter up so that it only lifted 30% of its mass, as it would be on Mars.
They used a high-tech reel, a brushed DC motor, a torque transducer and a block mounted high above the ceiling that pulled the fishing line with just the right amount of force.
We pumped out the air, turned on the gravitational unloading system, in fact, the helicopter ended up “on Mars” under the same conditions.