I found it:
http://www.flightglobal.com/Articles/2005/12/20/Navigation/200/203670/Inflatable+launcher+more+than+hot+air.html

It is a little low on details, but it looks like it uses an annular
aerospike nozzle.

It also has a very low payload fraction. Fueled weight is 47t, payload
into an unspecified low earth orbit is just 150kg.

I wonder why they have separate propellant tanks instead of integrating
them with the aeroshell.