Thanks for all the feedback. Bill has nailed it on the head, to paraphrase,
as a first level effort keep the hardware to a minimum number of parts, the
components and overall system as simple as is possible. This approach is
not new to the list or community. The effort though in our case is to apply
it to an LH2 system and develop methods with industry to safely use and
demystify LH2. Again we're not the first - Blue Origin and in particular
BMW at the civilian level. Bringing down the cost of this approach is also
a part of the project. Note not trying to preach or convince anyone this is
the way to go and appreciate all comments and critique.
It would appear based on the comments that we may wish or have to apply
some additional enhancement - method - to the pressurization system over a
simple blow down method.
If we could recover helium - with minimum loss, I would say yes that can be
factored back in. Keeping the system though to using the H2 and O2 gases is
desirable. The excess gas weight after the burn can be used in the RCS and
other potential on board tech.
LH2 has particularities and benefits compared to other fuels. The larger
volume tanks are not a problem as they were designed in to take advantage
of that aspect of LH2.
The first effort is of course entirely experimental to learn and evolve.
More complexity for performance etc can be applied over time (only as
needed).
Cheers
Brian Feeney
On Sun, Dec 13, 2015 at 10:25 AM, William Claybaugh <wclaybaugh2@xxxxxxxxx>
wrote:
LED's are not highly efficient and that could be an issue. One has to do
the engineering to see the relative costs.
Brian is proposing to pressure feed, so any turbo alternator will be a
stand alone device, not part of a turbopump.
Also note that the engine can be spun from stainless and use BLC for
cooling; previous analysis has shown that 20% extra H2 costs and weighs
less than an ablative motor.
This propellant combination has the potential to yield a relatively low
cost--and relatively high performance--liquid rocket if one focuses on
avoiding a conventional--and expensive--pressurization system.
Although the development cost might be higher than other alternatives,
controlled dripping of TEA into the LO2 tank could also generate
pressurizing gas in the tank.
Bill
On Saturday, December 12, 2015, John Stoffel <john@xxxxxxxxxxx> wrote:
sender "rcktman" for DMARC)> writes:"rcktman" == rcktman <<dmarc-noreply@xxxxxxxxxxxxx>(Redacted
rcktman> If gaseous H2 has absorbation bands in the IR, then tailoring
rcktman> the IR output of the heaters so the gas heats--and the liquid
rcktman> does not--has the potential to keep pressure up while
rcktman> minimizing boil off. The point here is that for a 2-4 minute
rcktman> burn one should design for a non-equilibrium state as between
rcktman> the gas and the liquid; stratify the gas, not the liquid.
It seems to me that the amount of energy required to run those IR LEDs
to head the Hydrogen gas is a non-trivial amount, and the batteries
(or generator hung off the turbopump shaft) is also a non-trivial
amount of weight.
And do IR LEDs even exist with that narrow and fixed bandgap? And
what about the waste heat from the LEDs? Does that get added into the
tank, or are the feedlines embeded around them for a little heat
exchang support?
Seems like alot of hassle and potential for boom when testing with
gaseous Hydrogen and you have a spark somewhere. Of course any spare
sparks will cause things to go boom.