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Just two questions here: 1)Does anyone happen to know how to calculate the specific impulse of a given propellant combination? I'm thinking Propellant-grade hydrogen peroxide and alcohol for a lunar lander, but I'm not sure about calculating the Isp for that particular combination.

2)The other thing regards unmanned cargo landers: Anyone looking into solid propellants for landing? Perhaps a 'rough-rider' system that came down like a semi-controlled bomb and used solids to brake velocity even with high acceleration loads. . . ?

Yes and Yes,

90% peroxide (90 parts H2O2 10 parts H2O) burned with 21 parts C2H5Oh or CH3OH (Ethanol or Methanol) 
at 300 psi, with a 40:1 expansion ration has a vacuum ISP of about 300.  :)

Well surveyor was a solid lander- mostly. It is nearly impossible to do without a controllable/throttlible descent engine (I've tried)

but Surveyor dumped most of it's orbital velocity with a solid that it ejected before landing. (3 vernier N2O4/N2H4 and 6 cold gas jets) 
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