Cards on the table. I’m a believer. Despite the immense technical challenges, Hydrogen is a viable fuel for future large civil aircraft. That said, operational service of such revolutionary aircraft isn’t going to happen in a hurry.
Reading the history, Concorde was an incredible test of the boundaries of what was possible and that was met, but it didn’t come easy. Breaking new ground is never easy. [A common saying that’s maybe open to challenge]. In aviation making step-changes happens every decade. What’s nearly always required is exceptional determination, almost beyond reason, large sums of money and special people.
Control systems – no big deal. Mechanical components – evolution possible. Turning a gaseous fuel into high-levels of propulsive thrust – can be done. Building a one-off technology proving research vehicle. It’s happening. At least for the light and commuter class of aircraft.
None of this is enough. Because the gap between an aircraft that can fly and an aircraft that can be produced in the thousands and go on to make an operational living and build an impressive safety and reliability reputation, that’s still a million miles off.
Today, there’s artist impressions of all sorts of different H2 aircraft configurations. It’s like people painted pictures of Mars with imaginary canals, long before anyone knew what the planet looked like in reality. Innovation starts with ideas and not all of them are sound.
As I expressed in my last article, crashworthiness must be given much consideration when speculating about future designs. It’s not always explicit in aircraft certification, cabin safety being the exception, but studying the history of accidents and incidents is essential. One of the successes of the authorities and industry working together is to take lessons learned seriously.
I remember looking at the pictures of the wreckage of Air France Flight 358, which crashed on landing in Toronto, Canada[1]. The fact that there were no fatalities from that accident is a testament to good operations and good design practices. The Airbus aircraft burned out but there was enough time for passengers and crew to get away.
My thought is what kind of H2 aircraft configurations would permit the same opportunity?
Considering this large aircraft accident, and others like it, then there’s a message as to where fuel tanks might best be placed. There’re some aircraft configurations that would have little hope of providing the opportunity for rapid evacuation of hundreds of people.
So, in my mind, don’t attached large pressurised cryogenic fuel tanks to the underbody structure of an aircraft fuselage. However robust the design and build of such fuel tanks they would be unlikely to survive as well as the cabin passenger seats, namely 9g[2]. That would not provide a good outcome post-accident.
Maybe, like aircraft engines sitting on pylons off the wings, that too is a good place for fuel tanks.
[1] https://asn.flightsafety.org/asndb/322361
[2] https://www.easa.europa.eu/sites/default/files/dfu/NPA%202013-20.pdf
John Vincent 