- Has silane ever seriously been considered as a potential rocket fuel and,
Yes silanes has been considered as fuels, at least during the early scramble to develop storable hypergolic propellants for missiles in the 40s and 50s.
In his book "Ignition!", rocket propellant pioneer John D. Clark mentions that the University of Texas tried silanes as an additive to make gasoline hypergolic with red fuming nitric acid (RFNA), the leading storable oxidizer of the time.
Gasoline was a tempting candidate for rocket fuel due to its availability, but unfortunately it was not hypergolic with RFNA, making it unsuitable. Considerable research effort was put into finding additives that could make it hypergolic.
Silanes worked for that. 30% tetra-allyl silane makes gasoline hypergolic.
But as many other attempts this did not manage to replace aniline-based fuels, and later low freezing derivatives of hydrazine made all of this obsolete.
It was also considered as a monopropellant too for some reason:
Stan [Tannenbaum] worked with N₂O₄ and with perchloryl fluoride. He found that he could mix bicyclooctane or decalin in N₂O without immediate
disaster, but that the mixture was too touchy to live with. He tried
tetramethyl silane too, in the hope (unrealized) that it would be
So at least there's a testimonial for it being less safe than straight up mixing hydrocarbons into perchloryl fluoride...