Isekai Craft Gurashi ~Jiyuu Kimama na Seisan Shoku no Honobono Slow Life~ - Ch. 36

[JavelinJoe]

Yeah, there's also the fact that putting what is, in essence, a jet engine in a tunnel basically turns the tunnel into a gun barrel. Guns work by burning propellant to massively increase gas pressure behind a bullet, which easily overcomes the atmospheric pressure on the other side. So this would be similar, except instead of burning propellant, you're actually shifting the mass of air from one side to the other.

Also, just so everyone knows, this isn't something the mangaka is pulling out of their ass. This is a thing that actually exists.
https://en.wikipedia.org/wiki/Atmospheric_railway

If only he knew about hydrolic or pneumatic breaks. The concept behind them is actually relatively simple enough to possibly even get lucky with a few tests. Especially if you are not trying to min/max cost and efficiency. He could simply over engineer it and make it work with brute force since once the technological concept is proven to work, he can just let the more suitable experts/craftsmen refine and optimize it.

The same could be done for the train as well if only he understood certain properties of electricity. Rail based propulsion would actually work here too, since the route probably wouldn't need to twist and turn a whole lot underground with the way he can build tunnels. One straight path means you could essentially just send it with a huge launch assist (like planes recieve on an aircraft carrier) and simply let friction over distance gradually slow it down until the breaks at the end take over and finish the job. Or chain it with several boost stations along the way if the magic/force is too much to handle to make it all the way in one go.

But alas, he just isn't that kind of guy. Group effort will have to do for now it seems.

 

[Amariithynar]

A steam engine would be nice... if they aren't building it under ground... (pretty sure thats what they were planning anyways), if thats the case if they don't do the ventalation very carefully people would just choke from no oxygen

Considering the size of the tunnel, they wouldn't asphyxiate, especially since it's intended to be sealed carriages. Especially since they can use fire blocks with a boiler, instead of relying solely on direct mechanical force from wind (since pushing on air is actually one of the worse ways to impart momentum).

 

[TheProtectorOfPureHeartedGirls]

Page 30: Too heavy, bro...
Condolence, is what I must say though.

Spoiler

 

[Claith]

Considering the size of the tunnel, they wouldn't asphyxiate, especially since it's intended to be sealed carriages. Especially since they can use fire blocks with a boiler, instead of relying solely on direct mechanical force from wind (since pushing on air is actually one of the worse ways to impart momentum).

While I'm happy that the conversation moved to why a steam engine or combustion engine wouldn't work, I don't think this is correct. The tunnel is 600 km long, and without proper ventilation gases would build up and become toxic over many trips.

It'd make more sense to use the hot water magic he set up for the bath to boil. Would get really moldy in the tunnel with all the water vapor though. Slime infestation likely.

I don't think that using wind is inherently bad. Might work out if the tunnel on the far side of the train was widened and the extra wind was dispersed from a wider outlet (spread the flow around instead of a jet), instead of up and down. Add a set of chimneys to vent the wind at the stations, and the stairs likely wouldn't be so windy. The lack of conservation of mass or forces in this series will drive me nuts one day.

If he was mechanically skilled, something that always turns, like a flywheel enchanted to move (don't remember if those floating sword things on his tower moved or not) attached to a clutch to the axles would be the most direct way. He'd have to figure out brakes first through, or a fluid "clutch" like a torque converter that automatics use if they wanted to engage while moving. When not moving, a gear based system could work, but they have to be careful not to "blow the transmission".

 

[Amariithynar]

While I'm happy that the conversation moved to why a steam engine or combustion engine wouldn't work, I don't think this is correct. The tunnel is 600 km long, and without proper ventilation gases would build up and become toxic over many trips.

It'd make more sense to use the hot water magic he set up for the bath to boil. Would get really moldy in the tunnel with all the water vapor though. Slime infestation likely.

Fire blocks dumping heat into a sealed steam vessel = no gases to ventilate. I already addressed this. You don't need to burn fuel to get the boiler operational.

I don't think that using wind is inherently bad. Might work out if the tunnel on the far side of the train was widened and the extra wind was dispersed from a wider outlet (spread the flow around instead of a jet), instead of up and down. Add a set of chimneys to vent the wind at the stations, and the stairs likely wouldn't be so windy.

The problem with wind and why it is inherently bad in the configuration they're doing is because it is wind pushing against air, which is incredibly poor for energy output to efficiency; cases where air pressure is useful is where you have a sudden explosion of pressure in a very small area that then propels a sealed-to-the-walls projectile, as with air rifles, pneumatic nail guns, and similar pneumatic tools.

The lack of conservation of mass or forces in this series will drive me nuts one day.

It's magic that generates things, that then operate as per basic laws of physics et al. Isn't it fun?

If he was mechanically skilled, something that always turns, like a flywheel enchanted to move (don't remember if those floating sword things on his tower moved or not) attached to a clutch to the axles would be the most direct way. He'd have to figure out brakes first through, or a fluid "clutch" like a torque converter that automatics use if they wanted to engage while moving. When not moving, a gear based system could work, but they have to be careful not to "blow the transmission".

Unironically, using wind to power a turbine that spun a flywheel up would be an actually great way to do it, even with a smaller amount of energy output. By storing mechanical energy in a flywheel, they can then dump it into the wheel system via gearing through a clutch and transmission system, or disconnect it via same, so as to not waste any excess energy still in the flywheel (to reduce charge time for the return trip).