Thank you gentlemen, those are excellent pieces of information answering a layman’s question. Here’s another.
Regarding saving lives, and crashworthiness, I’ve often wondered this of conventional helicopters and passenger aircraft of any size for that matter:
If they can drop a tank or large piece of field gear from a cargo plane via a parachute, why can’t they similarly lower a relatively light disabled aircraft, or fuselage, to the ground at 20MPH instead of 200?
The helicopter could have the “explosive bolts” on the rotor hub, and a braking mechanism on the tail rotor, allowing a clean drop of the core of the aircraft.
They’ve had “rocket fired parachutes” on ultralights for quite some time now.
It seems preserving the irreplacable human cargo, and maybe even the plane, would be well worth the weight penalty or additional cost.
The heaviest aircraft that’s been successfully parachute-saved is about 6000lbs. The Osprey in this article can weigh up to **60,000lbs.**
When they’re air dropping a 60,000lb static load from an airlifter, the aircraft has to be traveling under 170 knots at most or the parachutes don’t work. The parachutes and reinforced pallet structure needed to support the parachutes can also consist of up to 5Klbs of the weight. A single G-11 parachute weighs 250lbs. On a static 60K lb load being shoved out the back of an airlifter, you need 12 of the things, not an insignificant weight.
https://www.globalsecurity.org/military/systems/aircraft/systems/images/60klvads.jpg
https://www.globalsecurity.org/military/systems/aircraft/systems/60klvads.htm
Parachutes also occupy a lot of space. On the Very Light Jets and general aviation craft like the Cirrus SR-22 equipped with an airframe parachute, the single recovery parachute can take up 1/3 of the usable fuselage space.
Short version - all but the lightest planes and choppers can’t afford to give up the weight and space for parachute systems they are often moving too fast to be able to deploy safely anyway.
This is why ejector seats are common on military airplanes. And the Russians, who are better at choppers than we are, incorporate crew bailout or crew ejection systems in their newer helicopters.
Also, modern main battle tanks are not air droppable. In fact, the lack of an air drop capable armored vehicle with the retirement-without-replacement of the not-very-good M551 Sheridan ‘light tank with a big gun’ is currently causing some consternation in the Army and Marines.
The M1A2 SEP v4 ‘Super Abrams’ is already knocking on the door of 73 tons. The soon to be added Israeli Trophy active protection system will add another half a ton to that. That’s 147,000lbs before you fill the fuel tanks, install a basic ammo load on board, etc., etc. 42k lbs is considered the safe upper limit for parachute deployment systems we have with 60K being bleeding edge and sometimes not working.
