[Idea] JATOs for Airliners?

[Spacethingy]

Anybody remember this awesome event?

Or maybe this one?

My point being, if airliners had emergency JATOs, couldn't accidents like these be avoided - ones where just a few minutes (if that) of thrust could save the day?

 

[T.Neo]

Far too much danger from one of those JATOs going off when you don't want it to, or from it going off in a way that you don't want it to. Better to try and prevent such incidents in the first place.

 

[GigaG]

Actually a good idea, but-

Where would the JATO system be?
What about the sudden acceleration? Could they be certified for the public?
Could the wings handle the stress of sudden acceleration?

Also,T.Neo is right. Of course, the JATOs could be disconnected from the electrical system to prevent ignition, but they would need to be activated pretty quick from a cold standstill. Also, you would have to be able to jettison the JATOs so that if the plane crashed, the JATOs would not explode from post-crash firees.

BTW, the British Airways incident happened upon landing. Considering a fuel shortage near the runway would be a plausible reason to use these, I'm not sure if "JATO" is the right term. Considering that they could also be used in case the plane was about to overrun the runway (take off), maybe JATOL (L for Landing)?

 

[Moach]

my first thought would be that a significant amount of structural changes would be due in order to accommodate such a thing in a way that doesn't rip through the airframe once those are fired....

otherwise, there wouldn't be much thrust that could be safely added by using this


anyways, most airliners got thrust to spare... the only cases this can be am issue is in events of engine failure, but i don't think firing a rocket from an already troubled aircraft would be a solution more than it's be a problem :blink:

 

[Spacethingy]

Well, I'm guessing that the wings could take it. I know 747s aren't C130s, but still...

 

[Hielor]

Well, I'm guessing that the wings could take it. I know 747s aren't C130s, but still...

Note that those rockets are attached to the fuselage, not the wings.

There are very few accidents where an airliner overran the runway on takeoff. In almost all of those cases, they were rejected takeoffs, where the pilots made the decision (usually due to an engine failure) that they were better off on the ground than in the air. Another few seconds of thrust wouldn't be useful there.

There are far more examples of airliners departing the runway on landing. In the majority of these cases, by the time it's obvious that something's going to go wrong, it's far too late to get the plane back into the air safely, even if JATO was available.

One of the cardinal rules in aviation is "it's better to be on the ground wishing you were in the air than in the air wishing you were on the ground." Something to assist airliners with landing/slowing down would be a lot more important than something to assist them with taking off/speeding up, and these already exist at most major airports in the form of blast pads/overrun areas at the ends of runways that are designed to crush under the weight of an aircraft and bring it to a stop quickly.

From a more practical stance, these things would add dead weight for 99.99% of the flights you take, reducing the passenger load (and thus either reducing income per flight or increasing ticket costs) for no gain at all. That's in addition to the high up-front expense and continuing maintenance costs.

TL;DR version: No.

 

[N_Molson]

And you could only activate those once V1 (the non-return point) is reached. Because SRMs can't be shut off, once they are on, no abort (you can't drop them on the runway) !

Also, the SRMs would have to be super-tested as any failure would be catastrophic (one shut downs, the other burns normally ? Spin of death !).

And stocks of SRMs in airports, with the kerosene trucks, the crowd of airliners and passengers, the terrorists... hum... :hmm:

In my opinion, it's about as safe as letting a chimpanzee playing with a SPAS-15.

 

[Evil_Onyx]

My 2c

Adding extra single use boosters to an aircraft just makes no sense.

What happens if they fire early or late or not at all.
It would add more complexity and yet more training for the airline staff (when most airlines have a hard time providing the necessary training for the staff already).

What happens if the aircraft brakes up in the air? the boosters are most likely going to survive until they hit the ground where they could become time bombs.

What happens if the aircraft catches fire on the ground, could you make them so they would not start un-commanded even in the worst fire that can occur with an aircraft. If not i would see airports banning any aircraft fitted with them due to safety of fire and rescue crews.

In my opinion they would be more likely to create or worsen an emergency than help.

 

[Artlav]

Why?
It's upside is equivalent of having a bit more fuel, or a bit better gliding, but it's downside is more ka-booms of death.

Emergency deceleration rockets can seem to be useful, but still the same issue of being a manned solid rocket:

 

[Ghostrider]

It makes as much sense as putting parachutes on chairlifts. Moreover, those rockets are explosives waiting to go off and you don't put them on anything without good reason.

 

[N_Molson]

On an historical sidenote, the soviet military were first interested by rockets to boost their very slow combat planes, before the WWII. They got some results, but the rockets were too weak and too unpredictable to be used in combat. :blahblah:

 

[steph]

Would they be economical/acceptable? Nope. But they would be very, very cool . Isn't the USAF using them from time to time?

However, I like this better:

 

[Turbinator]

In my opinion, it's about as safe as letting a chimpanzee playing with a SPAS-15.

 

[iamwearingpants]

Forget the new Planet of the Apes, that is how it really happened!

 

[agentgonzo]

Why do you need a new rocket motor for an airliner for this. If the issue is that they ran out of thrust, then why not just take more fuel? If the plane was already full on fuel, then maybe drop-tanks to give them more fuel.

Also, the added expense of taking JATOs on every single flight? Do you seriously think that a single airline would approve carrying JATOs on every flight just in case? It's add a significant cost to each and every ticket.

 

[garyw]

Why do you need a new rocket motor for an airliner for this. If the issue is that they ran out of thrust, then why not just take more fuel? If the plane was already full on fuel, then maybe drop-tanks to give them more fuel.

The only 'reason' (and I use the term losely) for having JATO's would be the sort of situation like BA038 found itself in - a sudden demand for thrust but not having any from the engines. This was actually due to ice accumulating in the fuel lines breaking free and blocking the fuel filters. In this situation JATOs probably would have killed everyone on the plane rather than the resultant scrapes and bruises they received from a very hard landing.

Also, the added expense of taking JATOs on every single flight? Do you seriously think that a single airline would approve carrying JATOs on every flight just in case? It's add a significant cost to each and every ticket.

Plus the expense of the training, maintenance, certification, etc, etc and it would add zero to passenger safety.

 

[Moach]

i just got to thinking... and then it hit me

V1 is the speed at which there's "no return" and a plane must takeoff as there isn't enough runway to do an abort left

V2 is the speed at which it can safely continue climb should an engine happen to go out


in any nominal takeoff, aboard any plane built by sane individuals - those two marks are but mere seconds apart, so that window of a few tens of knots would be the only time where a JATO could possibly do any good in case of emergency....

in other words, emergency JATO is just simply not worth it :thumbup:


that, plus the pile of reasons given by everyone else....

i reckon it sounds like a good idea at first - but once a little logic is applied, it really does makes sense that planes don't have this


if i may throw in an alternative idea on a similar matter - why don't airliners have emergency drogue chutes? - many accidents due to being unable to stop could be prevented with a good parachute, no?

 

[Hielor]

V1 is the speed at which there's "no return" and a plane must takeoff as there isn't enough runway to do an abort left

V2 is the speed at which it can safely continue climb should an engine happen to go out


in any nominal takeoff, aboard any plane built by sane individuals - those two marks are but mere seconds apart, so that window of a few tens of knots would be the only time where a JATO could possibly do any good in case of emergency....

in other words, emergency JATO is just simply not worth it :thumbup:

Even then, unless the runway is really short, you should still be able to reach V2 from V1 on only one engine and takeoff anyway, even without JATO.

 

[Keatah]

Jato, Jabo, and brake chutes are too costly and weighty for commercial applications. Especially when companies calculate weight and hem and haw over a variable camber mechanism that adds 35kg to the total weight, but produces a fuel savings as if you took off 450kg.

 

[Fabri91]

Apparently some of Mexicana's 727s had a JATO system fitted for hot and high operations...http://www.airliners.net/aviation-forums/general_aviation/read.main/2070962/