2
$\begingroup$

Similar to : Is there a minimum number of people needed for an aircraft pushback?

After watching this video I wonder what would be the number of people required to manually push back a 747.

I know small aircraft is usually pushback by the pilot and if possible a wing walker. Large jet at large airport has a few people involved in the process. But manual pushback a large jet is a special event where you need lots of people. How many do you need?

$\endgroup$
  • 3
    $\begingroup$ There are too many factors when considering humans to count, this might make your question slightly unanswerable. $\endgroup$ – Valay_17 Mar 30 at 3:29
  • 1
    $\begingroup$ I fail to understand why this is not a dupe. You may highlight why and how your question is different. $\endgroup$ – Manu H Mar 30 at 8:24
  • 2
    $\begingroup$ @ManuH one question is talking about manual pushback with no machines, the other question is asking about minimum number of people spotting etc to safely push back with a tug / tractor / whatever. Not obvious from titles but more clear if you read the actual body of the questions. $\endgroup$ – quiet flyer Mar 30 at 14:51
  • $\begingroup$ @quietflyer such comment should be included in the question $\endgroup$ – Manu H Mar 31 at 9:07
  • $\begingroup$ @ManuH -- "But manual pushback a large jet is a special event where you need lots of people. " $\endgroup$ – quiet flyer Mar 31 at 13:59
3
$\begingroup$

The rope must be attached one end to the aircraft and another to some stationary point. Humans should push it onto the side from the middle point. This should amplify the force significantly, reducing the number of people required by at least the factor of ten or about, so I think somewhat all passengers could do, even if half of them is not fit (there are about 400 in three class layout and we need about 200 strong enough humans). Here is the description of the idea with all mathematics involved.

| improve this answer | |
$\endgroup$
  • 1
    $\begingroup$ @vasin1987 and h22-- It seems fair enough to assume a rope and a stationary anchor point are available, I guess. But why not assume some pulleys are available as well? Just a thought... Really I guess I am pointing out an ambiguity in the question as much as anything else. In a typical pushback situation no stationary anchor point in a suitable location may be available. $\endgroup$ – quiet flyer Mar 30 at 1:09
1
$\begingroup$

Drawbar pull for 747-8 is 31,100 kg.

Humans can safely push 20% of their body weight.

So you need 155,500 kg of humans.

If we assume 80 kg per human and round up we have 1950 humans.

This number is for using only your arms, so using whole body, as would probably be the case here, you can double it.

So 975 (1950) humans to push with whole body.

Pull is more efficient at 30%, so only 103667 kg of humans needed.

This adds to 650 (1300) humans of 80 kg rounded up with whole body.

No idea if this is actually true, although numbers are (barely) low enough that someone might have tried. The big practical issue is connecting all those humans to the plane.

Also, the actual numbers to move the plane at all should be significantly lower. This is the number of people needed for safely operating the plane in normal airport conditions including slight upward slope and some engine thrust resistance.

If you only need zero slope and engines off, you should be able to cut the numbers by more than a third. That you are happy with much lower speeds and distances than Boeing should cut the numbers further.

Also, what I knew and intended to mention but forgot. These are the safe numbers for constant and repeated work intended to avoid workplace injuries. Peak exertion for a one time stunt is something else. I am providing these numbers as a starting point because the exact circumstances are not mentioned.

| improve this answer | |
$\endgroup$
  • 1
    $\begingroup$ Where does the figure of pulling only 30% of your weight come from? I'm not an athlete, but I'm able to lift my own weight rather easily. If you look at truck pulling one person is pulling 30-40 tons... I would guess your answer is off by an magnitude. $\endgroup$ – vidarlo Mar 29 at 20:33
  • 1
    $\begingroup$ @vidarlo, the number is probably true in the sense that the force applied is 20% of the person's weight (weight is a force and is measured in N, not kg). However to pull a 40 t truck (weighing 390 kN on Earth), straight and level, you only need something on order of 5 kN. After all the towbar used to push back aircraft weighing up to 4400 kN can handle mere 305 kN. $\endgroup$ – Jan Hudec Mar 29 at 21:19
  • $\begingroup$ Hm, checking the linked diagram (page 78) it really seems like its saying you need ~170 kN to get the plane moving when fully loaded (the 305 kN figure is when the engines are already running at idle, which they shouldn't with people around). It still sounds like too much. In the truck pulling video the guy is not inclined even by 60°, so he is not pulling even twice his weight (he's helping himself with the rope, but that's relatively lose,so 2.5× max), which would be less than 1% of the ~355 kN weight of the truck… $\endgroup$ – Jan Hudec Mar 29 at 21:40
  • $\begingroup$ … Roller bearing are roller bearings and should have similar coefficient of friction and the higher tire pressure of the aircraft should result in less resistance, not more. So the about 4% (~170 kN, the engines stopped case) still seems to be rather much. $\endgroup$ – Jan Hudec Mar 29 at 21:43
  • $\begingroup$ @vidarlo I looked it up and the number is actually correct. It is just the wrong number. It was for using just your arms. Using whole body as would be the case here should roughly double it. So off by factor of two. The main confusion stems from the fact that it is not the number people commenting expect. This is the safe number not the maximum exertion. I'll edit to clarify that. I realized the confusion this might cause when I wrote the answer but forgot to mention it and just mentioned the issue with Boeing numbers explicitly. Oops. $\endgroup$ – Ville Niemi Mar 29 at 21:46
1
$\begingroup$

Looking at that video in full-screen 4K (it's still pretty blurry), I generously counted 13 people who looked like they had their hands on tires and/or wheel bogeies. So I'd say that it takes 13 people to push a 747 with engines running.

There are many additional people standing around, so there may have been more involved in getting it moving (the plane is already moving when the video started), so at a minimum, it takes 13 people to keep it moving.

There is no indication of how heavily loaded this particular plane is with pax, luggage/cargo or fuel, so this number may vary.

| improve this answer | |
$\endgroup$
0
$\begingroup$

In main aeroports(no aerodrome) the pushback is done by the push(There are 2 pushback procedures: with clamp or towbar.). I don't think it has ever been done by men so we can't answer your question (except theoretically using formulas)

maybe :W = F × D × cos (θ), where W corresponds to the work in joules (J), F to the force expressed in newtons (N), D to the distance in meters (m) and θ to the angle between the force and direction of the object's trajectory.(for know the force). This formula is just to know the the work of a force.i don't know the max of the work of a human's force so i can't divide and have the result.

If the intensity of the force is not known, it can be calculated from the mass of the object and its acceleration, assuming that there are no other forces acting on it. . The formula to apply is as follows: F = M × A.

we don't take this into account:In physics, work is closely linked to another type of measurement called power. It is a convenient way to quantify the speed at which work is

https://fr.wikihow.com/calculer-le-travail-d%27une-force

| improve this answer | |
$\endgroup$
  • 1
    $\begingroup$ Plane pulls are a thing, often for charity, so I wouldn't say they've never been done by men, though those are usually pulling the plane forward with the use of a rope and not back. $\endgroup$ – Zach Lipton Mar 29 at 17:31
  • $\begingroup$ Yeah maybe you're right $\endgroup$ – L'aviateur Mar 29 at 18:06
  • $\begingroup$ Could you put some numbers in these equations to come up with an answer for how many people it might take? $\endgroup$ – fooot Mar 29 at 18:15
  • 3
    $\begingroup$ In this situation acceration seems less of an issue than simply overcoming static friction and wheel rolling resistance. Accepting a very very low acceleration rate would still not allow one single person to accomplish the task unaided! $\endgroup$ – quiet flyer Mar 30 at 14:59
  • $\begingroup$ @ZachLipton there's nothing that says that a "Plane pull" has to be forward in relation to the plane. Assuming there's enough room under the belly for the puller(s), the "pull" could be backwards in relation to the direction the plane is pointing. Ergo, a "plane pull" is entirely valid for this example. Also, 2 of these super freaks could each have a rope, one standing on either side of the fuselage, and, working together, neither should have to break a sweat! $\endgroup$ – FreeMan Apr 1 at 13:11

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.