I wonder if Naphthalene would make a good additive to HTPB hybrid
propellant? It's a white powder (used mostly in mothballs) it sublimates
quite easily. It's a hydrocarbon, perhaps it would help stabilize hybrid
combustion?
I know adding AP to the HTPB helps combustion say 5%.
-------- Original Message --------
Subject: [AR] Re: Peltier specifications
From: Bill Claybaugh <wclaybaugh2@xxxxxxxxxx>
Date: Tue, August 04, 2015 2:04 pm
To: "arocket@xxxxxxxxxxxxx" <arocket@xxxxxxxxxxxxx>
Not really a preburner and not really adding any complexity; the TEA system
was needed for ignition, increasing the size of that tank was all that was
required to eliminate most combustion instability.
I can't speak to other technical solutions; but note that it does not require
all that much heat to vaporize a Lox fog.
Bill
Sent from my Commodore 64
On Aug 4, 2015, at 3:54 PM, Henry Vanderbilt <hvanderbilt@xxxxxxxxxxxxxx>
wrote:
Interesting. So if I'm understanding this correctly, you're talking about
something like an oxygen-rich preburner to make sure the oxidizer is
thoroughly vaporized as being useful for large hybrids.
Makes sense of what VG might be having methane onboard SS2 for. I'd been
wondering about that.
It sounds like the sort of thing one would come up with after already
committing to large hybrids, then hitting the (apparently fairly typical)
uneven combustion, to make them actually work. If you assume from the
start you'll need some sort of preburner with a separate fuel system, I'd
think large hybrids would lose their lower-parts-count edge over biprops in
the tradeoffs.
On 8/4/2015 11:37 AM, Bill Claybaugh wrote:
Mark:
It seems like an AN & ice water mix could be tailored to your temperature
goals. But why not go to a dry ice cooler and maximum density: a single
pass on a couple of coils should get you what you are seeking. LN2 is also
obviously an answer; both can be had in Mojave.
As Anthony has hinted, you will need a heat source at the head end to
assure the N2O fog is vaporized, otherwise combustion will be rough and
unstable. At Amroc we injected TEA throughout the burn to vaporize the
Lox; I gather VG is using Methane in the SS2 nylon motor.
Bill
Sent from my Commodore 64
On Aug 3, 2015, at 9:33 PM, Mark C Spiegl <mark.spiegl@xxxxxxxxx> wrote:
Wow... Im out of the office for a day and my inbox is full! :-)
Anyway.. Anyone who has followed my hybrid projects knows Im a fan of
high density Nitrous. Im looking to cool 20-50 lbs of Nitrous to 25-ish
degF.
Goals:
(1) Flashing liquid to vapor to chill Nitrous is fine in a motor burning
10-20 lbs of Nitrous. Much above 20lbs (esp in the desert), flashing
liquid to gas becomes impractical. I would like to start a little closer
to my target temperature of 22 degF. The Peltier, Stirling Cooler, or
whatever would chill the supply tank, not the rocket tank.
I know ice is a quick-and-dirty answer, but I would like something a
little more elegant and deterministic. Bags of ice aren't a great answer
at FAR or Blackrock.
(2) I have had trouble igniting high density Nitrous in warm weather.
Cold weather is no problem. I cannot prove what is happening, but I
suspect temperature gradients in the long thin Nitrous tank are causing
the problem. If the Nitrous is 22 degF at the top of the tank, it may be
much much colder at the injector. Supplying Nitrous close to the final
temperature should help mitigate this problem, if Im correct.
A related question: Any simple ways to equalize temperature between the
top and bottom of the rocket's oxidizer tank???
--MCS
(Im an EE kind of person so my solutions tend to feel like electronics...
ie Peltiers)