My last post should have read:
LH2 has *peculiarities*...
Cheers
Brian Feeney
On Sun, Dec 13, 2015 at 1:02 PM, Steve Traugott <stevegt@xxxxxxx> wrote:
Maybe I missed this, but has anyone tried a mini version of the ULA IVF?
Could use a modified R/C engine and flight-weight motor as generator.
Doing the math, I get about 100W from a 5cc engine using conservative
numbers; that's using a 4-stroke engine, brushed PM motor and keeping the
engine at lower RPMs to avoid the need for a gearbox; brushless multiphase
looks to be able to go higher with less weight and added electronics.
Total system weight appears to be around 2 Kg.
Problems to solve would include lubrication -- using a 4-stroke helps with
this. Not sure if the valving issues Frank discusses in his paper would be
critical.
Steve
On Sun, Dec 13, 2015 at 7:25 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.