The Airship Site

Energy required to move 300,000 tons through the atmosphere at roughly 100 knots?

Forgive me for any engineering or physical inaccuracies here, I’m only an IT major haha. I’ve been conducting a thought experiment with myself lately about heavy lift airships. I have devised a hypothetical way to lift about the same tonnage as the biggest surface freighter ships, but that is not relevant to this question. Mainly, I’m curious how one could move about 300,000 tons (airframe and payload weight combined) through the atmosphere at a competitive speed of around 100 knots. I understand the measure “horsepower” can be inaccurate and variable, but what measure of horsepower could achieve this? In my thought experiment, a high acceleration rate is not necessary. If these engines were electric, what amount of electrical energy would be required to power them? Thank you for any answers you all might be able to provide and I again apologize for the grossly ignorant and uninformed questions I may pose!

My favorite method for order-of-magnitude problems like this is to scale from existing designs.

So lets design Jumbo² by comparing to the Hindy. Per the link, the Hindenburg used 200,000 m³. Since air is 1.2kg/m³ at sea level, at 1 kg/m³ you’ll be able to go up to several thousand feet altitude. Zeppelins went 5k to 10k feet.

So, J² needs 3 x 10^8 m³, or 1500x the Hindy. Volumes scale by cubes, so J² dimensions are cube root of 1500 or 11.5x larger.

Now, Hindy top speed of 84mph vs. J² speed of 115mph means Hindy needs 1.37x more speed. Drag goes with the square, power with the cube (Force x Velocity). So, 1.37³ = 2.566x more power for higher speed. For bigger size, drag is 11.5² higher. Thus, J² power, assuming similar shape to the very efficient Hindy, would be the Hindy 4800 HP times 2.566 x 131 = 1.6 million HP. This amount of power isn’t easy to come by.

But, the bigger problem is that Hindy length of 800 feet is pushing structural capabilities. Going 11.5x bigger is incredible task, not clear if it is even possible.

airship hanger prototype