Brian:
As you may know, blowdown systems using self-pressurized Lox have been used
by amateurs for more than half a century (Jim Nudding of the PRS for
hybrids, in the 1950's, as an example). Environmental heat is sufficient
if you size the tank L/D correctly. The Lox will be warm and you will get
lower density in consequence.
Local heating to the surface can provide makeup pressure if you want
constant pressure through the burn.
Hydrogen is tougher using traditional assumptions but I would not do that:
a "cold" radiant heat source at the top of the tank (i.e., IR LED's) can
provide lots of gas while keeping the overall liquid cold; the obvious
trick is in keeping control of the system, for which modern control systems
appear to be more than sufficient: if a four rotor helicopter is stable
enough to be sold as a toy, keeping control of the local heating and
pressurization of a cryogen ought to be in family.
Simple systems tend to be lower cost and higher reliability....
Bill
On Fri, Dec 11, 2015 at 5:11 PM, Brian Feeney <alaiadesign@xxxxxxxxx> wrote:
Bill, what cycle are you suggesting to boil the liquids? Self pressurizing
to 300 psi for LOX to O2 gas certainly works and has been demonstrated
along with methane. Self P for LH2 is I believe, under that pressure range.
It was mentioned to me years ago that LH2 may have some other difficulties
in a self pressurizing system given its extreme cryogen nature.
Stratification? I don't though have a good handle on it one way or the
other.
Cheers
Brian Feeney
On 2015-12-11 4:55 PM, "William Claybaugh" <wclaybaugh2@xxxxxxxxx> wrote: