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The Structures engineers are quite pleased and the Maintenance folks are positively ecstatic. The Cargo people are very happy that storage areas are easily accessible and that all passengers will have a window. The Aerodynamics guys have looked at it and concluded they are not involved.Those engines do look nifty, but that airframe sure could do with some work
Sir let me congratulate to you this brilliant! summary....The Structures engineers are quite pleased and the Maintenance folks are positively ecstatic. The Cargo people are very happy that storage areas are easily accessible and that all passengers will have a window. The Aerodynamics guys have looked at it and concluded they are not involved.
The Structures engineers are quite pleased and the Maintenance folks are positively ecstatic. The Cargo people are very happy that storage areas are easily accessible and that all passengers will have a window. The Aerodynamics guys have looked at it and concluded they are not involved.
Several years ago someone came up with a hybrid drone that used electric motors for VTOL but flew conventionally once aloft. That makes some sense. Charging the batteries to provide additional power required for takeoff and landing is directly analogous to the electric motors used in hybrid automobiles, which are used as "afterburners" to give otherwise excessively puny engines adequate performance. They have also gone to using hybrid locomotives as switch engines in RR yards, since they can power them from batteries and use a large diesel pickup truck engine to charge the batteries that starts and stops automatically as required rather than running a much larger diesel engine 24/7 for moving RR cars short distances.how it sounds: hybrid propulsion - we are converting chemical bonds energy stored in fuel through mechanical means to electrical energy to convert it in mechanical energy
i've spend last 12 months working in project initially assumed hybrid propulsion - so far conclusion is that applicability of this idea is limited to aircrafts up to around 100-120 kg MTOW, only because of distributed propulsion application - like UHP drones. Going bigger is bad idea due pretty bad mass gain and hopeless battery performance.Several years ago someone came up with a hybrid drone that used electric motors for VTOL but flew conventionally once aloft. That makes some sense. Charging the batteries to provide additional power required for takeoff and landing is directly analogous to the electric motors used in hybrid automobiles, which are used as "afterburners" to give otherwise excessively puny engines adequate performance. They have also gone to using hybrid locomotives as switch engines in RR yards, since they can power them from batteries and use a large diesel pickup truck engine to charge the batteries that starts and stops automatically as required rather than running a much larger diesel engine 24/7 for moving RR cars short distances.
But how this concept applies to an aircraft with a 2500 mile range, with electric motors as the only propulsion, and powered by a internal combustion engine, I do not think I understand.
interesting - one of my colegues is working on H2 tank project right now - made of CFRP - your calcs were relatad to tank made of metallic materials? By the way - LNG cars are pretty popular here in Poland - this is fairly easy to handle technology.I did a study for Kennedy Space Center on the probability of failure of composite pressure vessels. I found that a high pressure (3600 PSI) Compressed Natural Gas tank capable of holding the same energy as 10 gal of gasoline weighs 100 lb, empty, and is about 3 ft long and 18 inches long; full of CNG, the tank weighs about 150 lb.
For a tank holding compressed hydrogen gas, the same figures apply to a tank capable of holding the energy equivalent of 2 gallons of gasoline.
CNG is an entirely feasible off-the-shelf technology for automobiles and offers some advantages over gasoline as an energy source, such as lower costs and better safety, as well some disadvantages. But its hard to see how it could be successfully applied to aircraft; batteries are even worse when it comes to energy density.
I think your analysis could be extremely interesting for the guys who are working on H2 tank project here - is it publicly available? any chance to take detailed look on it?No, the concern was for composite technology tanks, such as fiberglass or carbon fiber, not metal, although some use metal liners. KSC had a tank fail and then they began to wonder just how failure prone they are. Theoretically they last for thousands of years, but the question is "What is the reality?" As it turned out a the Defense Technical Info Service had a contractor try to do a study on the subject but the industry flat out refused to cooperate. So I had to do an intelligence gathering operation rather than just a study. And I found data that enabled you to estimate the probability of failure, much of it based on actual news reports associated with failures. When a tank blows up and takes off someone's foot, it is hard to cover up the incident. The big factor is ENVIRONMENTAL in nature. When someone spills sulfuric acid on the surface of a composite tank it may just look like a little discoloration but the end result may well be catastrophic. Aside from that, some tanks have a service life and you exceed that at your peril.
Probably the best approach is to use a titanium liner, overwrap it with carbon fiber composite, and then put a layer of fiberglass atop that. The fiberglass is not as strong as the carbon fiber but is much more forgiving to environmental conditions; it protects the carbon fiber.
And in terms of safety, the tanks are designed to automatically vent their contents if the temperature exceeds a certain value. When they vent, the fuel goes up rapidly and any fire tends to take place away from the vehicle, not pooling on the ground as liquid fuels do. There was one incident where someone screwed up installing a tape deck in CNG powered shuttle bus and it stared and electrical fire one night when the bus was in garage. The fire resulted in the CNG tank venting and the gas going up to the ceiling, where it was ignited by a sparking light. Only burn marks on the ceiling resulted, repairable by just some paint. If it had been gasoline or diesel powered buses in that garage the tape deck fire probably would have blown the whole building off the map.
And as for the "bomb" aspect of the pressure tanks, they are so robust that any vehicular mishap that ruptures the tank will prove to be fatal to the people involved anyway.