14 added 18 characters in body edited Nov 21 '19 at 23:33 Gryphon 10.5k33 gold badges4848 silver badges8686 bronze badges Full Disclaimer: I am the OP of this question, so this answer may be biased towards this being possible. TL;DR: If we make some optimistic assumptions, this may be possible without even having to mess around with atmospheric density and/or gravity! I've decided to work out an example creature with a total body mass (without the mass of the hydrogen) of $$500kg$$. According to Dubukay's excellent answer, Hydrogen has a lifting capacity of about $$1.1 kg/m^3$$. This means that to lift our $$500kg$$ beast, we need about $$455 m^3$$ of H2. Assuming this hydrogen is kept in a spherical container (which isn't quite accurate but is a good enough approximation for now) and that my math is right, this container will need about $$286 m^2$$ of whatever surface is used to contain the hydrogen for the outside of its gasbag. According to this paper, the wing loading for a bat can get as low as $$0.14 g/cm^2$$. Wing loading is mass of the bat per cm^2 of wing loadingsurface, so actual bat wings will be muchseveral times thinner because a substantial portionmost of their body mass is their actual body. Therefore, we can assume this as an upper limit for wing mass. We need $$286 m^2$$ of surface area, which means that if we use the same skin bats do for their wings (probably several layers of it due to this being an upper bound, which will make the gasbag even stronger), so if my math is correct, the outer skin of the gasbag will weigh a touch over $$400 kg$$. This means we are able to retain almost $$100kg$$ of weight for any necessary vital organs, steering and locomotion devices such as flippers and flaps, and hydrogen generation apparatus. Of course, this makes some optimistic assumptions, such as assuming a perfectly spherical shape for the hydrogen containment organ, but we can cut quite far into that remaining 100kg of lifted mass before we begin to run into issues with the requisite mass of vital organs, so this concept seems to be at least somewhat feasible, and the gasbag will be several times stronger than the wing of a bat, which should be sufficient for most purposes. Amusingly, this also demonstrates that if you could find a way of connecting bats together in a way that prevented the leakage of hydrogen, a $$400kg$$ sphere of bats filled with hydrogen could easily lift an adult. Full Disclaimer: I am the OP of this question, so this answer may be biased towards this being possible. TL;DR: If we make some optimistic assumptions, this may be possible without even having to mess around with atmospheric density and/or gravity! I've decided to work out an example creature with a total body mass (without the mass of the hydrogen) of $$500kg$$. According to Dubukay's excellent answer, Hydrogen has a lifting capacity of about $$1.1 kg/m^3$$. This means that to lift our $$500kg$$ beast, we need about $$455 m^3$$ of H2. Assuming this hydrogen is kept in a spherical container (which isn't quite accurate but is a good enough approximation for now) and that my math is right, this container will need about $$286 m^2$$ of whatever surface is used to contain the hydrogen for the outside of its gasbag. According to this paper, the wing loading for a bat can get as low as $$0.14 g/cm^2$$. Wing loading is mass per cm^2 of wing loading, so actual bat wings will be much thinner because a substantial portion of their body mass is their actual body. Therefore, we can assume this as an upper limit for wing mass. We need $$286 m^2$$ of surface area, which means that if we use the same skin bats do for their wings (probably several layers of it due to this being an upper bound, which will make the gasbag even stronger), so if my math is correct, the outer skin of the gasbag will weigh a touch over $$400 kg$$. This means we are able to retain almost $$100kg$$ of weight for any necessary vital organs, steering and locomotion devices such as flippers and flaps, and hydrogen generation apparatus. Of course, this makes some optimistic assumptions, such as assuming a perfectly spherical shape for the hydrogen containment organ, but we can cut quite far into that remaining 100kg before we begin to run into issues with the requisite mass of vital organs, so this concept seems to be at least somewhat feasible, and the gasbag will be several times stronger than the wing of a bat, which should be sufficient for most purposes. Amusingly, this also demonstrates that if you could find a way of connecting bats together in a way that prevented the leakage of hydrogen, a $$400kg$$ sphere of bats filled with hydrogen could easily lift an adult. Full Disclaimer: I am the OP of this question, so this answer may be biased towards this being possible. TL;DR: If we make some optimistic assumptions, this may be possible without even having to mess around with atmospheric density and/or gravity! I've decided to work out an example creature with a total body mass (without the mass of the hydrogen) of $$500kg$$. According to Dubukay's excellent answer, Hydrogen has a lifting capacity of about $$1.1 kg/m^3$$. This means that to lift our $$500kg$$ beast, we need about $$455 m^3$$ of H2. Assuming this hydrogen is kept in a spherical container (which isn't quite accurate but is a good enough approximation for now) and that my math is right, this container will need about $$286 m^2$$ of whatever surface is used to contain the hydrogen for the outside of its gasbag. According to this paper, the wing loading for a bat can get as low as $$0.14 g/cm^2$$. Wing loading is mass of the bat per cm^2 of wing surface, so actual bat wings will be several times thinner because most of their body mass is their actual body. Therefore, we can assume this as an upper limit for wing mass. We need $$286 m^2$$ of surface area, which means that if we use the same skin bats do for their wings (probably several layers of it due to this being an upper bound, which will make the gasbag even stronger), so if my math is correct, the outer skin of the gasbag will weigh a touch over $$400 kg$$. This means we are able to retain almost $$100kg$$ of weight for any necessary vital organs, steering and locomotion devices such as flippers and flaps, and hydrogen generation apparatus. Of course, this makes some optimistic assumptions, such as assuming a perfectly spherical shape for the hydrogen containment organ, but we can cut quite far into that remaining 100kg of lifted mass before we begin to run into issues with the requisite mass of vital organs, so this concept seems to be at least somewhat feasible, and the gasbag will be several times stronger than the wing of a bat, which should be sufficient for most purposes. Amusingly, this also demonstrates that if you could find a way of connecting bats together in a way that prevented the leakage of hydrogen, a $$400kg$$ sphere of bats filled with hydrogen could easily lift an adult. 13 added 10 characters in body edited Sep 28 '19 at 7:28 Gryphon 10.5k33 gold badges4848 silver badges8686 bronze badges Full Disclaimer: I am the OP of this question, so this answer may be biased towards this being possible. TL;DR: If we make some optimistic assumptions, this may be possible without even having to changemess around with atmospheric density and/or gravity! I've decided to work out an example creature with a total body mass (without the mass of the hydrogen) of $$500kg$$. According to Dubukay's excellent answer, Hydrogen has a lifting capacity of about $$1.1 kg/m^3$$. This means that to lift our $$500kg$$ beast, we need about $$455 m^3$$ of H2. Assuming this hydrogen is kept in a spherical container (which isn't quite accurate but is a good enough approximation for now) and that my math is right, this container will need about $$286 m^2$$ of whatever surface is used to contain the hydrogen for the outside of its gasbag. According to this paper, the wing loading for a bat can get as low as $$0.14 g/cm^2$$. Wing loading is mass per cm^2 of wing loading, so actual bat wings will be much thinner because a substantial portion of their body mass is their actual body. Therefore, we can assume this as an upper limit for wing mass. We need $$286 m^2$$ of surface area, which means that if we use the same skin bats do for their wings (probably several layers of it due to this being an upper bound, which will make the gasbag even stronger), so if my math is correct, the outer skin of the gasbag will weigh a touch over $$400 kg$$. This means we are able to retain almost $$100kg$$ of weight for any necessary vital organs, steering and locomotion devices such as flippers and flaps, and hydrogen generation apparatus. Of course, this makes some optimistic assumptions, such as assuming a perfectly spherical shape for the hydrogen containment organ, but we can cut quite far into that remaining 100kg before we begin to run into issues with the requisite mass of vital organs, so this concept seems to be at least somewhat feasible, and the gasbag will be several times stronger than the wing of a bat, which should be sufficient for most purposes. Amusingly, this also demonstrates that if you could find a way of connecting bats together in a way that prevented the leakage of hydrogen, a $$400kg$$ sphere of bats filled with hydrogen could easily lift an adult. Full Disclaimer: I am the OP of this question, so this answer may be biased towards this being possible. TL;DR: If we make some optimistic assumptions, this may be possible without even having to change atmospheric density and/or gravity! I've decided to work out an example creature with a total body mass (without the mass of the hydrogen) of $$500kg$$. According to Dubukay's excellent answer, Hydrogen has a lifting capacity of about $$1.1 kg/m^3$$. This means that to lift our $$500kg$$ beast, we need about $$455 m^3$$ of H2. Assuming this hydrogen is kept in a spherical container (which isn't quite accurate but is a good enough approximation for now) and that my math is right, this container will need about $$286 m^2$$ of whatever surface is used to contain the hydrogen for the outside of its gasbag. According to this paper, the wing loading for a bat can get as low as $$0.14 g/cm^2$$. Wing loading is mass per cm^2 of wing loading, so actual bat wings will be much thinner because a substantial portion of their body mass is their actual body. Therefore, we can assume this as an upper limit for wing mass. We need $$286 m^2$$ of surface area, which means that if we use the same skin bats do for their wings (probably several layers of it due to this being an upper bound, which will make the gasbag even stronger), so if my math is correct, the outer skin of the gasbag will weigh a touch over $$400 kg$$. This means we are able to retain almost $$100kg$$ of weight for any necessary vital organs, steering and locomotion devices such as flippers and flaps, and hydrogen generation apparatus. Of course, this makes some optimistic assumptions, such as assuming a perfectly spherical shape for the hydrogen containment organ, but we can cut quite far into that remaining 100kg before we begin to run into issues with the requisite mass of vital organs, so this concept seems to be at least somewhat feasible, and the gasbag will be several times stronger than the wing of a bat, which should be sufficient for most purposes. Amusingly, this also demonstrates that if you could find a way of connecting bats together in a way that prevented the leakage of hydrogen, a $$400kg$$ sphere of bats filled with hydrogen could easily lift an adult. Full Disclaimer: I am the OP of this question, so this answer may be biased towards this being possible. TL;DR: If we make some optimistic assumptions, this may be possible without even having to mess around with atmospheric density and/or gravity! I've decided to work out an example creature with a total body mass (without the mass of the hydrogen) of $$500kg$$. According to Dubukay's excellent answer, Hydrogen has a lifting capacity of about $$1.1 kg/m^3$$. This means that to lift our $$500kg$$ beast, we need about $$455 m^3$$ of H2. Assuming this hydrogen is kept in a spherical container (which isn't quite accurate but is a good enough approximation for now) and that my math is right, this container will need about $$286 m^2$$ of whatever surface is used to contain the hydrogen for the outside of its gasbag. According to this paper, the wing loading for a bat can get as low as $$0.14 g/cm^2$$. Wing loading is mass per cm^2 of wing loading, so actual bat wings will be much thinner because a substantial portion of their body mass is their actual body. Therefore, we can assume this as an upper limit for wing mass. We need $$286 m^2$$ of surface area, which means that if we use the same skin bats do for their wings (probably several layers of it due to this being an upper bound, which will make the gasbag even stronger), so if my math is correct, the outer skin of the gasbag will weigh a touch over $$400 kg$$. This means we are able to retain almost $$100kg$$ of weight for any necessary vital organs, steering and locomotion devices such as flippers and flaps, and hydrogen generation apparatus. Of course, this makes some optimistic assumptions, such as assuming a perfectly spherical shape for the hydrogen containment organ, but we can cut quite far into that remaining 100kg before we begin to run into issues with the requisite mass of vital organs, so this concept seems to be at least somewhat feasible, and the gasbag will be several times stronger than the wing of a bat, which should be sufficient for most purposes. Amusingly, this also demonstrates that if you could find a way of connecting bats together in a way that prevented the leakage of hydrogen, a $$400kg$$ sphere of bats filled with hydrogen could easily lift an adult. 12 added 19 characters in body edited Apr 4 '19 at 16:09 Gryphon 10.5k33 gold badges4848 silver badges8686 bronze badges Full Disclaimer: I am the OP of this question, so this answer may be biased towards this being possible. TL;DR: If we make some optimistic assumptions, this may be possible without even having to change atmospheric density and/or gravity! I've decided to work out an example creature with a total body mass (without the mass of the hydrogen) of $$500kg$$. According to Dubukay's excellent answer, Hydrogen has a lifting capacity of about $$1.1 kg/m^3$$. This means that to lift our $$500kg$$ beast, we need about $$455 m^3$$ of H2. Assuming this hydrogen is kept in a spherical container (which isn't quite accurate but is a good enough approximation for now) and that my math is right, this container will need about $$286 m^2$$ of whatever surface is used to contain the hydrogen for the outside of its gasbag. According to this paper, the wing loading for a bat can get as low as $$0.14 g/cm^2$$. Wing loading is mass per cm^2 of wing loading, so actual bat wings will be much thinner because a substantial portion of their body mass is their actual body. Therefore, we can assume this as an upper limit for wing mass. We need $$286 m^2$$ of surface area, which means that if we use the same skin bats do for their wings (probably several layers of it due to this being an upper bound, which will make the gasbag even stronger), so if my math is correct, the outer skin of the gasbag will weigh a touch over $$400 kg$$. This means we are able to retain almost $$100kg$$ of weight for any necessary vital organs, steering and locomotion devices such as flippers and flaps, and hydrogen generation apparatus. Of course, this makes some optimistic assumptions, such as assuming a perfectly spherical shape for the hydrogen containment organ, but we can cut quite far into that remaining 100kg before we begin to run into issues with the requisite mass of vital organs, so this concept seems to be at least somewhat feasible, and the gasbag will be several times stronger than the wing of a bat, which should be sufficient for most purposes. Amusingly, this also demonstrates that if you could find a way of connecting bats together in a way that prevented the leakage of hydrogen, a $$400kg$$ sphere of bats filled with hydrogen could easily lift an adult. Full Disclaimer: I am the OP of this question, so this answer may be biased towards this being possible. TL;DR: If we make some optimistic assumptions, this may be possible without even having to change atmospheric density and/or gravity! I've decided to work out an example creature with a total body mass (without the mass of the hydrogen) of $$500kg$$. According to Dubukay's excellent answer, Hydrogen has a lifting capacity of about $$1.1 kg/m^3$$. This means that to lift our $$500kg$$ beast, we need about $$455 m^3$$ of H2. Assuming this hydrogen is kept in a spherical container (which isn't quite accurate but is a good enough approximation for now) and that my math is right, this container will need about $$286 m^2$$ of whatever surface is used to contain the hydrogen for the outside of its gasbag. According to this paper, the wing loading for a bat can get as low as $$0.14 g/cm^2$$. Wing loading is mass per cm^2 of wing loading, so actual bat wings will be much thinner because a substantial portion of their body mass is their actual body. Therefore, we can assume this as an upper limit for wing mass. We need $$286 m^2$$ of surface area, which means that if we use the same skin bats do for their wings (probably several layers of it due to this being an upper bound, which will make the gasbag even stronger), so if my math is correct, the outer skin of the gasbag will weigh a touch over $$400 kg$$. This means we are able to retain almost $$100kg$$ of weight for any necessary vital organs, steering and locomotion devices such as flippers and flaps, and hydrogen generation apparatus. Of course, this makes some optimistic assumptions, such as assuming a perfectly spherical shape for the hydrogen containment organ, but we can cut quite far into that 100kg before we run into issues with the requisite mass of vital organs, so this concept seems to be at least somewhat feasible, and the gasbag will be several times stronger than the wing of a bat, which should be sufficient for most purposes. Amusingly, this also demonstrates that if you could find a way of connecting bats together in a way that prevented the leakage of hydrogen, a $$400kg$$ sphere of bats filled with hydrogen could easily lift an adult. Full Disclaimer: I am the OP of this question, so this answer may be biased towards this being possible. TL;DR: If we make some optimistic assumptions, this may be possible without even having to change atmospheric density and/or gravity! I've decided to work out an example creature with a total body mass (without the mass of the hydrogen) of $$500kg$$. According to Dubukay's excellent answer, Hydrogen has a lifting capacity of about $$1.1 kg/m^3$$. This means that to lift our $$500kg$$ beast, we need about $$455 m^3$$ of H2. Assuming this hydrogen is kept in a spherical container (which isn't quite accurate but is a good enough approximation for now) and that my math is right, this container will need about $$286 m^2$$ of whatever surface is used to contain the hydrogen for the outside of its gasbag. According to this paper, the wing loading for a bat can get as low as $$0.14 g/cm^2$$. Wing loading is mass per cm^2 of wing loading, so actual bat wings will be much thinner because a substantial portion of their body mass is their actual body. Therefore, we can assume this as an upper limit for wing mass. We need $$286 m^2$$ of surface area, which means that if we use the same skin bats do for their wings (probably several layers of it due to this being an upper bound, which will make the gasbag even stronger), so if my math is correct, the outer skin of the gasbag will weigh a touch over $$400 kg$$. This means we are able to retain almost $$100kg$$ of weight for any necessary vital organs, steering and locomotion devices such as flippers and flaps, and hydrogen generation apparatus. Of course, this makes some optimistic assumptions, such as assuming a perfectly spherical shape for the hydrogen containment organ, but we can cut quite far into that remaining 100kg before we begin to run into issues with the requisite mass of vital organs, so this concept seems to be at least somewhat feasible, and the gasbag will be several times stronger than the wing of a bat, which should be sufficient for most purposes. Amusingly, this also demonstrates that if you could find a way of connecting bats together in a way that prevented the leakage of hydrogen, a $$400kg$$ sphere of bats filled with hydrogen could easily lift an adult. 11 added 8 characters in body edited Mar 23 '19 at 19:33 Gryphon 10.5k33 gold badges4848 silver badges8686 bronze badges 10 added 209 characters in body edited Mar 21 '19 at 16:08 Gryphon 10.5k33 gold badges4848 silver badges8686 bronze badges 9 added 21 characters in body edited Mar 14 '19 at 19:50 Gryphon 10.5k33 gold badges4848 silver badges8686 bronze badges 8 added 242 characters in body edited Mar 6 '19 at 16:01 Gryphon 10.5k33 gold badges4848 silver badges8686 bronze badges 7 added 64 characters in body edited Mar 6 '19 at 13:43 Gryphon 10.5k33 gold badges4848 silver badges8686 bronze badges 6 added 87 characters in body edited Mar 5 '19 at 13:50 Gryphon 10.5k33 gold badges4848 silver badges8686 bronze badges 5 added 72 characters in body edited Feb 28 '19 at 0:17 Gryphon 10.5k33 gold badges4848 silver badges8686 bronze badges 4 added 30 characters in body edited Feb 4 '19 at 16:01 Gryphon 10.5k33 gold badges4848 silver badges8686 bronze badges 3 deleted 20 characters in body edited Jan 30 '19 at 18:53 Gryphon 10.5k33 gold badges4848 silver badges8686 bronze badges 2 corrected grammar and spelling edited Jan 30 '19 at 1:17 Gryphon 10.5k33 gold badges4848 silver badges8686 bronze badges 1 answered Jan 29 '19 at 20:50 Gryphon 10.5k33 gold badges4848 silver badges8686 bronze badges