Right, but it was an aside based on John Mace’s comment that it is easier if the treadmill is going with you. Elvis said, no, it doesn’t make a difference. When, actually, it would, as the treadmill would move the tired forward, and whatever friction there is between surface and wheel hub would impart momentum.
Corry El was taking it a step further by imaging the brakes being on, and ending up with the concept of an aircraft carrier.
If an aircraft carrier were traveling into the wind at or above the stall speed of the jets on it’s runway, they would take off.
Well, yeah. But if you had a pilot in one, and you brought the carrier up to stall speed, he could lift off and hover right over the deck. Same for landing, for that matter.
We are talking stall speeds for fighter jets, which is generally going to be a touch faster than a carrier can go.
What if the carrier is going full speed all engines blasting waves ahoy and then hits a corral reef and stops in its tracks? Would the planes then glide off or hover peacefully until a solution was found?
But a good fraction of it. A carrier can hit 30 knots or so, and if it’s going into a 20 knot wind then you have 50 knots over the wings before you even start the engines. An F/A-18E has a stall speed around 135 knots.
One only had to be paying attention in high school physics.
Um, okay, real life.
The airplane flies when the wings are at what you call “flight speed” relative to the air. No, it doesn’t matter how you get there; that’s when the airplane flies.
Your point that an airplane can go in the water off a carrier if it has a cold cat shot or some other equipment failure is true enough, but not responsive to the OP. No, a reverse treadmill will not affect takeoff any more than a forward one. Yes, pedants, there is such a thing as rolling friction, but the OP isn’t asking that either.
The title of the thread is ‘Can an Airplane Take Off on a Moving Runway’. A carrier is the only actual practical example of a ‘moving runway’. So it seems strange to call discussion of this case off point in favor of exclusively discussing the wacky conveyor case. Anyway I made it perfectly clear I was speaking of carrier take off.
And NOT using catapult (again WWII carriers generally didn’t use them, sometimes didn’t have them) to avoid the confusion you might be falling into if thinking the functioning of the catapult is all that matters…though in a post above you seemed to understand that relative wind over deck IOW how fast the moving runway is moving absolutely matters for carrier takeoff, strange.
Anyway in the real case of a plane taking off (whether catapulted or not but let’s stick to non-catapult to simplify) from a ‘moving runway’ aka a/c carrier, the carrier’s speed matters because the plane won’t ever reach flying speed if the required takeoff run to reach it is longer, in length, than the available deck space. And the required length of takeoff run is a function of the carrier’s plus the wind’s speed, for a given plane in a given condition (of load). And that length could be insufficient without any equipment failure, say if somebody really thought ‘high school physics’ meant it didn’t matter how fast the carrier was going and slowed down enough to extend the required take off roll length to greater than available deck length.
