I just described why we cannot expect to see Zeppelins return in the cul-de-sac thread. But a lot of work is being done on very high flying unmanned airships and there are good reasons to continue to think about cargo and even passenger airships.
One point: fuel consumption. Hindenburg with four diesel engines of 1200 PS ( PS is a little smaller than hp ) reached a speed of about 130 km/h max., so will have used four times 600 PS to fly at her cruising speed of 100 km/h. Assuming 250 grams per PS.h she would have burned less than four tons of diesel fuel in the 61 hours from Frankfurt to Lakehurst. She loaded seven tons for such a journey - that includes fuel for services and reserves so the calculation is reasonable. She could carry 72 passengers, mail and a few tons of cargo. Only taking into account the passengers that is about 55 kg per passenger for a transatlantic journey. It was about 1000 kg per passenger with Concorde to mention the other extreme. The world might be hit by a solar storm that might cause flying at 10,000 meters to become dangerous over a large part of the world for a few days, or Betelgeuse might have blown up and cause disruption over a period of months(?). The magnetic field of the Earth might turn over and cause trouble for years or centuries, we don't know yet. No reason to abandon flying tomorrow, but enough reason to think about alternatives. And one point stands out. There is no reason to travel with great speed and in the discomfort of an airliner seat, accepting tasteless airline food in order to make contact with someone far away: the internet is much faster. When you're not in a hurry you can travel in an airship with much more comfort, even work while travelling and arrive fresh to meet your friend at the other side of the world.
I hope other members will be interested in technical speculation as well as in reviewing modern successful and failed airship projects.
One point: fuel consumption. Hindenburg with four diesel engines of 1200 PS ( PS is a little smaller than hp ) reached a speed of about 130 km/h max., so will have used four times 600 PS to fly at her cruising speed of 100 km/h. Assuming 250 grams per PS.h she would have burned less than four tons of diesel fuel in the 61 hours from Frankfurt to Lakehurst. She loaded seven tons for such a journey - that includes fuel for services and reserves so the calculation is reasonable. She could carry 72 passengers, mail and a few tons of cargo. Only taking into account the passengers that is about 55 kg per passenger for a transatlantic journey. It was about 1000 kg per passenger with Concorde to mention the other extreme. The world might be hit by a solar storm that might cause flying at 10,000 meters to become dangerous over a large part of the world for a few days, or Betelgeuse might have blown up and cause disruption over a period of months(?). The magnetic field of the Earth might turn over and cause trouble for years or centuries, we don't know yet. No reason to abandon flying tomorrow, but enough reason to think about alternatives. And one point stands out. There is no reason to travel with great speed and in the discomfort of an airliner seat, accepting tasteless airline food in order to make contact with someone far away: the internet is much faster. When you're not in a hurry you can travel in an airship with much more comfort, even work while travelling and arrive fresh to meet your friend at the other side of the world.
I hope other members will be interested in technical speculation as well as in reviewing modern successful and failed airship projects.