You wrote: "You'll find that the detonation velocity for hydrogen-air at STP is 1968 m/sec"
But, conditions in the combustor will be much different.
Air will be adiabatically heated by compression be several hundred degrees C. This does several things, including greatly increasing the detonation velocity.
Next, it is possible to have a continuous ignition energy applied to the mixture by microwaves. These will produce a glow discharge which will generate lots of hydrogen atoms, which react very rapidly with oxygen in air.
Mixing of hydrogen with air seems to be a problem, but it may be amenable of solution as well.
David F Mayer
