Purpose - 1.) Presentation and evaluation of selected past and present design projects for passenger aircraft with liquid hydrogen (LH2) propulsion. LH2 aircraft are also referred to as cryoplanes. 2.) Research question: Can cryoplanes be "zero emission"? 3.) Information for everyone interested. --- Methodology - Revisiting of HAW Hamburg past research projects. Literature review. Combination of given knowledge to new insight. --- Findings - An A319 cabin fits almost into a LH2 cryoplane based on an A321 fuselage. Such a design limits investment into new aircraft. It needs 40% more energy, 20% more DOC and shows about 27% less environmental burden (considering emissions and energy based on a LCA) if(!) hydrogen is from electrolysis and electricity from renewable sources. However, since electricity has to be taken from the grid with given energy mix, a cryoplane is as polluting as a kerosene plane, but has the advantage that it burdens future generations less due to its predominantly short term non-CO2 emission effects. Renewable energy will by far not be sufficient to maintain flying at the level we know today (2019). It is therefore paramount to reduce flying as it happened already during the Corona pandemic. Nevertheless, the aviation industry maintains the physically implausible "zero emission" goal based on advanced technology, because otherwise the credo "aviation needs growth" will not convince politics and society and could result in restrictions. This is why industry cannot enter a technical debate about: "How much 'zero emission' is possible?". Maintaining the extreme position of "zero emission" by means of a hydrogen powered aircraft contributed further to truth decays in the aviation industry. Notwithstanding these problems, we need to find a sincere way to communicate while we abide in ethical standards like "do not lie". --- Practical implications - Results are presented in a pragmatic way. --- Social implications - A discussion based on facts is facilitated beyond scientific circles and can build up political pressure to initiate change in aviation into a direction which is really ecological. --- Originality/value - A presentation spanning from in depth aircraft design to social implications is otherwise missing, but most probably needed if we want to avoid a knowledge monopoly with the aviation industry that dictates the rest of society what has to be done.

Hamburg Aerospace Lecture Series --- Collection of Presentations --- http://www.AeroLectures.de