Comment on why do reverse thrusters work on an airplane, but a fan on a sailboat doesn't work?
bitteroldcoot@piefed.social 6 hours ago
Size matters. Airplane engines create a huge trust. A simple house fan does almost nothing.
A jet engine can blow a car end over end. A house fan just barely causes some paper to move.
gastroglizzy@piefed.social 6 hours ago
No fan of any size will ever push the boat it’s mounted to; that’s not how physics works.
remon@ani.social 6 hours ago
That’s pretty much exactly how a propeller works …
gastroglizzy@piefed.social 6 hours ago
Show me one airboat with a sail on it, you dunce.
remon@ani.social 6 hours ago
The great thing about air boats is they don’t need sails.
CarbonIceDragon@pawb.social 2 hours ago
It can be, as long as the sail is set up in such a way that incoming air is deflected backwards to some degree rather than at a right angle to the fan (such as with a curved sail). Consider a still boat in still air (thus with no net acceleration in any direction to start). You push some air forwards towards the sail, then the sail deflects that stream of air outwards and slightly backwards. This means the combined fan-sail system (the ship taken as a whole) is taking in initially still air, and that air ends up with a net momentum backwards, so there must be push forwards. This is very inefficient compared to doing away with the sail and pointing the fan the other way, so theres no reason to do it in practice, but it doesn’t violate conservation of momentum or anything because the ship isn’t a closed system.
bitteroldcoot@piefed.social 6 hours ago
So you have never seen an airboat?
https://en.wikipedia.org/wiki/Airboat
gastroglizzy@piefed.social 6 hours ago
Have you ever seen an airboat with a sail?