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Would a tractor beam consisting of a powerful suction force be usable as a method of grabbing targets at a maximum range of about 10yd? This is obviously only applicable when not in the vacuum of space, and would have a vent right before the fan, so as to avoid slicing up whatever was "grabbed". Would this work at all? If so, would a 150 pound creature survive the trip?

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    $\begingroup$ Over what kind of range? A running jet airliner engine, for instance, can pull in a human being walking within, say, 10m of it, but not much further than that. $\endgroup$
    – Cadence
    Commented Nov 14, 2022 at 3:13
  • $\begingroup$ That's about the distance I was thinking $\endgroup$ Commented Nov 14, 2022 at 3:37
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    $\begingroup$ Not sure tractor beam is the right word for this even in jest, a suction hoover doohickey will lack more than a few of the performance characteristics of a tractor beam as generally depicted in sci fi .. for a start you won't be able to hold anything in position at a desired distance for sure, nor control the speed of approach or repulsion, it's going to be an all or nothing speed in relation to speed. $\endgroup$
    – Pelinore
    Commented Nov 14, 2022 at 11:53
  • $\begingroup$ @Cadence Although 10 m is the recommended forward clearance distance of a jet engine, I don't think we can conclude from that alone that a person could be sucked in at that range. Those hazard zones are also going to be there to make sure that dropped gear, loose clothing, etc. would also be unlikely to be pulled in... and surely have a healthy margin for "I didn't realize how close I was to the engine". $\endgroup$ Commented Nov 14, 2022 at 20:49
  • $\begingroup$ If you have access to a fan you could experiment putting your hand behind it and notice that there is way less airflow from where the air is being pulled than where the air is being blown. This is the problem of this idea: The vacuum cleaner tractor beam would need to be basically right next to the thing it's trying to pull to work. $\endgroup$ Commented Nov 15, 2022 at 1:58

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No

The fundamental problem with this idea is that technically vacuum cleaners don't 'suck' they just allow the air on the other side to 'blow'. (Go ahead and get all the juvenile jokes out of your system now.) Creating a low pressure zone means that the air will rush in from higher pressure zones until an equilibrium is reached. In turn, this means that even if the nozzle of your I'd-like-to-be-a-tractor-beam vacuum cleaner could create a perfect vacuum (which it cannot), the maximum pressure differential that can be achieved is one atmosphere. That's directly in front of the nozzle - if you're talking about trying to hoover up a person even five metres in front of the nozzle then the air is rushing in from all directions and the pressure differential - and consequent wind speed - is much less.

Experiments and accidents involving rapid depressurisation of aircraft and spacecraft show that it is possible for people right next to a breach to be sucked (blown) through it. They need to be right next to it, though - even a few metres of separation is enough to allow them to avoid that fate if they have something to hold onto. You might be able to capture someone some metres further away if you put them on a perfectly smooth, oil-slicked surface... In practical terms, though, if they are close enough to be captured by a big vacuum cleaner then they are close enough to be grabbed by a mechanical arm that can be extended a few metres.

Consider also that the "tractor-vacuum" will be creating a vacuum that will result in everything of sufficiently low density being pulled in. So there is no chance of just capturing one person, unless everyone else is much further away, along with all the bags, litter, dirt, vegetation, animals etc filling the sphere whose radius the target person is also within.

Note that when Mythbusters were attempting the scuba-diver-sucked-up-by-water-bomber myth that they were unable to maintain a good enough seal to keep hold of the "diver" in order to even get them out of the water, let alone carry them anywhere. Admittedly that was using a pump designed to suck up water, but the results are indicative.

In summary - if a person is close enough to capture with a giant vacuum cleaner, they are close enough to grab with a mechanical arm that will use a tiny fraction of the power and will be far more selective.

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