On Tue, 24 Apr 2018, Jake Anderson wrote:
There was a brief surge of interest in this and other "free radical" propellants at one point in the 50s...
Metallic hydrogen (or Bob Forward's metastable helium), if it's stable at reasonable pressures once made, does seem more appealing.
A metallic hydrogen hybrid, that sounds like fun.
For somebody else to try, somewhere a long way from me....
Or do you just go the whole hog and make a SOX (Solid Oxygen) / Metallic hydrogen solid rocket and call it a day.