Hi Tony and Doug,
Wasn't sure exactly how much 0.019 mJ is, I like different units like
Temperature. So looked it up and it turned out to be 500 C, a very
reasonable number, Mach 0.8 in room temperature Hydrogen (or Mach 3 in
Air). That is Stagnation Temperature, but the air is never brought to a
stop. Instead the air is really being accelerated while turned, not slowed.
So, Room temperature Hydrogen injected at Mach 1 in Hydrogen is moving at
Mach 4 relative to the Air. There should be plenty of room below 500C to
use cold fast moving Hydrogen to turn the flow in front of the Nose Cone up
to Mach 6 or 7 without reaching the ignition point. I'm really not sure
what the limiting speed would be because it is dependent on so many other
design aspects of the injector turn.
I'm sure there would be some designs that go above 500C causing premature
ignition, or back firing. But that's the challenge, figuring out how to
make the first turn to the flow without ignition
It takes three turns for air to flow around an object. The first turn can
be the injection turn, where the hydrogen is used to turn and accelerate
the air. It's Spreading the Air and making room for the Vehicle.
The second turn is in the reverse direction from the injection turn.
The third turn to return it to normal.
These three turns correspond to the Double Sonic Boom that we hear when an
object is flying faster than the speed of sound. The first turn is the Bow
Shockwave, the second turn is the Expansion Fan and the third turn is the
Wake Shockwave. Ba----Boom.
I still don't see the problem with 0.019 mJ ignition energy. It's a feature
to be used during the second turn.
--
Craig Fink
WeBeGood@xxxxxxxxx
On Tue, Jul 9, 2019 at 6:21 PM Troy Prideaux <troy@xxxxxxxxxxxxxxxxxxxxx>
wrote:
*From:* arocket-bounce@xxxxxxxxxxxxx [mailto:arocket-bounce@xxxxxxxxxxxxx]
*On Behalf Of *Craig Fink
*Sent:* Tuesday, 9 July 2019 11:57 PM
*To:* arocket@xxxxxxxxxxxxx
*Subject:* [AR] Re: Orion Abort Test Failure...
Yes, Helium would work too, a great propellant but pretty much a dead end
as a fuel. The first time I heard about using a rocket to reduce drag was
back in the 1980s in a conversation about someone at JSC who wanted to do
it back in the 1970s. Fifty years and nobody has actually done it? Do you
have a copy of this professor's paper? I'd like to read it to see if he
actually understands the part about removing the Sound Barrier and what the
Subsonic Hydrogen flow field would behave like in a Supersonic Tunnel of
Air? I have many more interesting question on top of that.
Hydrogen does not spontaneously combust in air. I was NOT talking about
igniting the Hydrogen,
Well, you might have little choice. If (as Doug shared) the minimum
ignition energy (MIE) of a hydrogen/air mixture is only 0.019 mJ; that
should roughly translate to a… well… not incredibly high specific
stagnation enthalpy threshold to initiate … well… party mode.
Troy
