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<blockquote data-quote="Janx" data-source="post: 5215425" data-attributes="member: 8835">This.I Am Not a Rocket Scientist, so my next comments should only be taken as somebody who has watched a few Discovery channel shows... <img src="https://cdn.jsdelivr.net/joypixels/assets/8.0/png/unicode/64/1f642.png" class="smilie smilie--emoji" loading="lazy" width="64" height="64" alt=":)" title="Smile&nbsp; &nbsp; :)"&nbsp; data-smilie="1"data-shortname=":)" />Rockets don't push against the ground with their exhaust for propulsion.&nbsp; They rely on Newton's laws.&nbsp; this is proven by rockets in space travelling to the moon.&nbsp; The exhaust at some point is most assuredly not point at anything and pushing, yet still has effect.the more practical example is sitting in a small boat and throwing balls off it.&nbsp; The boat will be propelled in the opposite direction as the ball.As for helicopters and hovercraft lift mechanisms (and ignoring ground effect discussions a bit):hovercraft get their lift by directing air in high downward force.&nbsp; The skirts and such do probably rely on ground-effect and such.A helicopter, though its blades may generate a downward wind (like a ceiling fan) is relying on a different effect.&nbsp; Here's where I'm not fully certain of which mechanism it uses...the rotors are either trying to &quot;screw&quot; into the air to provide lift, which i don't think is likely, or like an air plan wing, are trying to create a high and low pressure differential that causes lift.Given that rotors also seem to be able to change their pitch, this would seem to support the cork-screw effect, but I'm pretty sure that was never a viable flight mechanism.Somebody else can probably provide clarity on the nature of helicopter lift.</blockquote>

[QUOTE="Janx, post: 5215425, member: 8835"] This. I Am Not a Rocket Scientist, so my next comments should only be taken as somebody who has watched a few Discovery channel shows... :) Rockets don't push against the ground with their exhaust for propulsion. They rely on Newton's laws. this is proven by rockets in space travelling to the moon. The exhaust at some point is most assuredly not point at anything and pushing, yet still has effect. the more practical example is sitting in a small boat and throwing balls off it. The boat will be propelled in the opposite direction as the ball. As for helicopters and hovercraft lift mechanisms (and ignoring ground effect discussions a bit): hovercraft get their lift by directing air in high downward force. The skirts and such do probably rely on ground-effect and such. A helicopter, though its blades may generate a downward wind (like a ceiling fan) is relying on a different effect. Here's where I'm not fully certain of which mechanism it uses... the rotors are either trying to "screw" into the air to provide lift, which i don't think is likely, or like an air plan wing, are trying to create a high and low pressure differential that causes lift. Given that rotors also seem to be able to change their pitch, this would seem to support the cork-screw effect, but I'm pretty sure that was never a viable flight mechanism. Somebody else can probably provide clarity on the nature of helicopter lift. [/QUOTE]

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