(Warning, for the humor challenged: this is tongue in cheek)
Some airplanes, such as the Cirrus, come equipped with rocket deployed parachutes that will allow the entire airplane to descend with relative safety. Cirrus claims that more than 60 lives have been saved by CAPS. Never mind that the the Cirrus overall has one of the worst safety records in the air.
A Cessna 172, on the other hand, actually descends more slowly than a parachute if it loses power.
So we could, at least in theory, pack parachutes into the bodies or wings of airliners. Or we could give them variable configuration wings that would allow them to glide to safety in the event of an emergency. After all, variable configuration wings have been around since the invention of flaps.
Or maybe we could just keep emergency supplies of Valium on board. The passengers will still die, but at least they won’t care.
You forgot to link to the column.
Leaving aside the “variable wings” scenario, the problem with parachutes attached to passenger planes has already been pointed out by Uncle Cecil: Most accidents happen close to or on the ground. Now for the small percentage of incidents where a parachute(if such a thing could be devised) might be of use, it would mean that the crew would have to cease all attempts to bring the aircraft under control and deploy the drag shoot.
Yes-drag shoot. That is what it will become when it is deployed on a jet speeding along 0.8 Mach or so. Can anyone imagine what will happen to a jet travelling at that speed if a parachute designed to land a 767 acts as a drag shoot? I can’t…and I don’t want to.
A Boeing 767 weighs between 315,000 and 450,000 pounds, depending on model and take-off weight. How large a parachute would be necessary, and how much might the parachute itself weigh?
Aircraft travel is already much safer than many other modes of travel, and where it can be made safer is almost certainly not in trying to fit the aircraft with a ginormous parachute. Which begs the question, what is the most cost-effective way to increase aircraft safety?
And I would guess (though I have no actual relevant knowledge), that in most of the accidents in which the problem does become apparent at cruising altitude, there is at least some realistic chance (right up until there isn’t) that the pilot might be able to successfully execute an emergency landing, such that sitting back and letting the pilot do his job would still give everyone a larger chance of survival than any mass-parachuting attempt would.
Indeed, when I read Cecil’s answer I recalled that I read a magazine article back when my father subscribed to both MI and Popular Science, suggesting that it would be practical to design aircraft with passenger cabins that would detach from the rest of the plane during an (otherwise survivable) in-flight emergency and float to Earth on a parachute system.
Still sounds far-fetched given how much a passenger compartment with fat-ass Americans must now weight, not to mention the expense of designing and building an entirely new aircraft for the very, very nervous
I’m going to round it to 400,000 pounds to make my calculations easier. A 200 pound person can descend at a survivable rate under a 28 foot diameter round parachute. Using the formula pi x r² I get an area of just over 600 square feet (again, I’m rounding to make it easier). So it takes approx. 3 square feet for every pound of suspended weight.
3 x 400,000 = 1,200,000 sq. feet. Divide that by pi and we get 382,166. The square root of 382,166 is approx. 618 so that’s the radius of our parachute, or a diameter of 1236 feet.
That’s a pretty big parachute. The 28 foot diameter (600 sq. ft.) parachute I described earlier weighs about 15 pounds so our 1,200,000 sq. ft. parachute would probably weigh thousands of pounds. And being deployed at 500 mph would probably rip it to shreds.
for today’s larger aircraft you would need the plane split up into smaller compartments. compartments would have to be balanced with passenger weight distribution. your ticket price would no longer be based on meals or seat room but on which order the pods would be jettisoned and allowed to clear before the next released.
Why not just make the airplane out of a parachute? Build a giant version of one of these- one that could hold 100+ people. Engine failure? No problem, you’ve already got an open parachute over your head! You just float to the ground.
Of course it’s a little slower than a commercial jetliner, with a forward speed of 25 mph (less in a head wind). On the plus side, you get a great view.
The 'chute wouldn’t deploy at 500 mph. First, a drogue 'chute would be deployed to stabilise the aircraft and to slow it down to a speed where the main 'chute could be deployed. I recall that there are some systems where a retaining ring prevents full inflation of the main 'chute until a safe speed is reached.
But as has been noted, there is no need to so equip airliners. They’re safe enough already. In the extremely rare event where a full-recovery parachute might be useful… Well, as dad used to say, ‘Them’s the breaks of Naval warfare.’
Thanks for that clarification. I was thinking about it after I made that post, and remembered the Apollo missions. They used parachutes to slow the descent of the capsules, which were going a lot faster than 500 mph. Do you know if they used a system similar to what you described? Or do any other Dopers know?
