The ballistic parachute It is a security system designed to save passengers and the entire aircraft in emergency situations, such as low altitude failures or control loss. Olded by a handle in the cabin, a small rocket expels a large parachute connected to the fuselage, allowing the plane to slowly go down to the ground. This system, effective on light planes, It cannot be installed on large scheduled planes For several reasons. The size and weight of a parachute capable of supporting a jet would be prohibitive, increasing consumption and emissions. But the insurmountable problem is the speed: to open a parachute to hundreds of kilometers per hour would generate one strait so violent as to disintegrate the plane and leave no escape to passengers.
What is a ballistic parachute, how it works and which planes is installed
The concept is not new. For light planes There are the so -called ballistic parachutesdeveloped for the first time by Ballistic Recovery Systems (BRS) in Minnesota. These systems are designed to enter into operation in critical conditions: at low altitude, at low speed, even in the case of uncontrolled lives, that is, when the plane crashes by rotating on itself. Situations in which a normal parachute would not even be able to open.
The operation recalls that of the ejectorable seats: a chain reaction that cannot be stopped.
In the event of an emergency, the pilot pulls a handle positioned in the cabin. This gesture activates a percussor – a sort of mechanical trigger – which triggers a pyrotechnic cartridge, that is, a small explosive. The charge turns on the solid propellant of the rocket which, through its push, expels the parachute.
Before being launched, the rocket, if necessary, pushes away a plexiglass panel and expels the package containing the parachute, launching it away from the plane to prevent it from imposing on the structure or in any propellers.
But the real problem is the speed of the plane: if the parachute it opened instantaneously it would cause such a violent strait to damage the plane and the pilot. The engineering solution adopted is the slider (or cursor): a simple ring of fabric which, at the time of expulsion, prevents parachute from opening up immediately and completely. This device flows slowly along the ropes of the parachute, gradually regulating the opening of the cap so as to reduce the initial impact with the air and limiting excessive stresses.
The parachute is firmly connected to the structure of the plane with fixing straps and ropes in synthetic material or in kevlar. These are often melted or glued inside (or above) the fuselage and stretch during the opening, keeping the plane hooked.
The main objective is to save people, not to preserve the plane, which usually undergoes damage.
Why don’t line planes have a parachute?
The technical reasons why the line planes do not have a giant parachute are numerous: with colossal dimensions, to weight, up to the huge opening loads. For small planes, the ballistic parachutes remain an effective solution. But for commercial flights, security continues to depend on what we already know: careful maintenance, redundant systems and rigorous procedures.
Greatness
We consider a medium line plane, like a Airbus A320 weighs 75 tons a parachute of 150 meters in diameter, which is equivalent to a field and a half football. Or if we take A Boeing 747 that weighs about 400 tonsto slow it down to 7 m/s 360 meters parachutewhich is equivalent to almost 4 football fields. Only the fabric would weigh between 10 and 20 tons.
The weight and consumption
In addition to the fabric, ropes, anchoring structures and expulsion rockets should be added: extra tons. Result? More fuel consumption, more emissions and more expensive tickets.
Opening loads
The most serious problem is the force at the time of opening. A scheduled plane never drops below 250-300 km/h. Opening a parachute at these speed means producing a devastating strait, a peak of forces: fuselage, cables and above all passengers would undergo unsustainable stresses. It’s like opening an umbrella on the highway.
The opening time
Such a system should open up gradually, in several seconds. But often the accidents take place at low altitudes: the parachute would not have time to fully unfold.
