Timeline for Does an aircraft landing on a carrier increase the carrier weight before it touches down?
Current License: CC BY-SA 3.0
18 events
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| Jan 6, 2015 at 16:57 | comment | added | Tyler Durden | This really has nothing to do with the question, but for the record most of the vertical force of a helicopter blade is due to positive displacement of air dependent on the the blade pitch angle not airfoil lift. In fact, it is possible to make a propeller or helicopter rotor out of a completely flat blade that is not an airfoil at all. | |
| Jan 6, 2015 at 16:33 | comment | added | reirab | @Jongosi Downward thrust is lift, at least for all practical purposes. You could argue that part (or most) of the lift is generated by 'pulling' air downward rather than 'pushing' it downward, but, either way, the downward force excerpted on the air is exactly equal in magnitude to the weight of the helicopter when it's not accelerating vertically. When moving horizontally, the airframe itself probably also generates some lift, but, again, it's generated by deflecting air downwards. Regardless of whether it's pushed or pulled, the change in momentum of the air will equal that of the aircraft | |
| Jan 6, 2015 at 16:22 | comment | added | Jongosi | @reirab No, it does not. The primary force opposing the helicopter's weight is lift, not downward thrust. Google vindicates me; google.co.uk/… A helicopter pulls itself into the air, it does not push away from the earth. | |
| Dec 31, 2014 at 5:34 | comment | added | reirab | @Jongosi Actually, it does. It represents 100% of the aircraft's weight (directly underneath the blades, at least... the effect on the ground will be less.) The total force applied to the air under the rotors of a hovering helicopter will be exactly equal to the lift generated by the rotors, though. As with all forces, the forces are equal and opposite. | |
| Nov 21, 2014 at 11:49 | comment | added | Jongosi | @TylerDurden You are mistaken; a helicopter does not "push" itself away from the ground, rather the rotor blades generate lift (they are mini-wings, essentially), "pulling" it upwards into the air. Obv we know that there is an opposite reaction of downward force from the blades, but it does not necessarily represent X proportion of the aircraft's weight. | |
| Nov 21, 2014 at 3:59 | history | edited | Tyler Durden | CC BY-SA 3.0 |
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| Nov 21, 2014 at 0:42 | comment | added | David Richerby | @PeterMasiar Weight is a force. Any other force is a force. In that sense, all forces "feel like weight". But that doesn't make them weight. | |
| Nov 21, 2014 at 0:38 | comment | added | Peter M. - stands for Monica | OK I can see that it is not "aircraft weight" what changes - but result (downward force on the aircraft) will behave exactly like increased weight (will push carrier down, and so slightly that it will be not measurable). So we need to define "before". :-) | |
| Nov 21, 2014 at 0:32 | comment | added | Marcks Thomas | @PeterMasiar: Perhaps you've misunderstood this answer. The air underneath a landing aircraft does push the carrier down, but 'weight' is not the correct name for this downward force; that name is reserved for the component caused by gravity. | |
| Nov 21, 2014 at 0:20 | comment | added | Peter M. - stands for Monica | @Tyler Durden Downward force towards carrier before landing is slight but not zero. I might not have aviation credentials but remember my Newton laws. If you disagree, take it to physics experts to decide. | |
| Nov 21, 2014 at 0:17 | comment | added | Rhino Driver | @PeterMasiar Peter Kampf is incorrect, the weight of the carrier doesn't increase until the aircraft touches the deck. Displacement increases as a force is applied, but the weight remains the same. | |
| Nov 21, 2014 at 0:16 | comment | added | Tyler Durden | @SHAF Yes, I recomputed the PSI, appears to be only 1-2 PSI. | |
| Nov 21, 2014 at 0:15 | history | edited | Tyler Durden | CC BY-SA 3.0 |
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| Nov 21, 2014 at 0:12 | comment | added | Tyler Durden | @PeterMasiar You are right it is a physics question, but just claiming somebody is "obviously wrong" without giving any reason is against the principles of Stack Exchange. Consider that you have 0 reputation and no credentials whatsoever, and have offered no reasoning whatsoever, its kind of BS for you to go around talking about how wrong somebody is. | |
| Nov 21, 2014 at 0:09 | comment | added | Tyler Durden | @SHAF just because a helicopter weighs a certain amount does not mean that amount of force is applied to the GROUND. The PSI will show a gradient from the blades to the ground. At the blades it will be the weight of the helicopter, but then it will decrease from there. | |
| Nov 20, 2014 at 23:46 | comment | added | Peter M. - stands for Monica | Not sure how this (IMHO) obviously wrong answer gained 3 upvotes. @Peter Kämpf is right. Maybe we should let physics exchange to decide this one. | |
| Nov 20, 2014 at 23:35 | comment | added | Rhino Driver | I generally agree, but helicopters don't weigh 72,000. Hovering, a helicopter should displace it's weight in air. | |
| Nov 20, 2014 at 20:57 | history | answered | Tyler Durden | CC BY-SA 3.0 |