Yes you could use a cat bed, but you don't need to as long as you have
another ignition source. It was a decade ago and I was still in University,
so I would agree that it was perhaps not the best technical solution.
I was more saying that you can inject a relatively hard to vaporize liquid,
like prechilled nitrous would be, into a hybrid and get stable combustion.
And that while adding a TEA to the combustion is one solution, and if the
TEA system is already there it is quite possibly the best solution, it is
also possible to modify the motor geometry to get stable combustion with a
liquid injection hybrid.
Lloyd
On Wed, Aug 5, 2015 at 10:05 AM, Bill Claybaugh <wclaybaugh2@xxxxxxxxxx>
wrote:
If using peroxide, wouldn't a catalyst bed serve to produce oxygenated
steam? That has been the usual solution for peroxide hybrids....
Bill
Sent from my Commodore 64
On Aug 4, 2015, at 4:34 PM, Lloyd Droppers <ldroppers@xxxxxxxxx> wrote:
Andrew: You certainly can directly inject liquid into the head end of a
hybrid make it work, but something like a traditional nitrous injector only
works because they function by the nitrous flashing to vapor on injection
so you need some way to vaporize the liquid. To vaporize the liquid you
need 2 things: small droplets and time. A impinging injector will work to
create the small droplets, but you might also need to add a precombustion
(to give the nitrous time to vaporize before it hits the fuel) and
postcombustion chamber (to make certain that any vapor that made it through
has time to combust) for it to work well. This obviously comes at the cost
of a larger motor, and Bills suggestion of injecting a fuel or TEA would
also work to assist vaporization at the cost of some complexity.
A few years ago I did some work on peroxide hybrids (25-1000 lbf) and we
used commercial spray nozzles for atomization and a small post combustion
chamber and we didn't notice much if any combustion instability.
http://www.responsivespace.com/Papers/RS4/Papers/RS4_4004P_Tsohas.pdf
Mark: Ice is totally reasonable at FAR and is probably the best. The
Jawbone Canyon store is only about 15 miles away, and sells ices by the 20
lb bag. Otherwise for the temperatures you are looking at if you wanted
more of a turnkey solution there are freezers for RV's and car camping that
run on 12V. They usually are rated to get to 0F and cost about $300 new.
Just make sure you search for a compressor freezer so you don't buy a
peltier refrigerator instead.
Lloyd
On Wed, Aug 5, 2015 at 6:54 AM, Andrew Burns <burns.andrew@xxxxxxxxx>
wrote:
Is there a reason while traditional like on like impinging injectors
can't be used to atomise and subsequently vaporise LOX or nitrous in a
hybrid? Is it something to do with getting the droplets to interact with
the fuel boundary layer?
Andrew
On Wed, Aug 5, 2015 at 6:37 AM, Bill Claybaugh <wclaybaugh2@xxxxxxxxxx>
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:
high density Nitrous. Im looking to cool 20-50 lbs of Nitrous to 25-ish
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
degF.
burning 10-20 lbs of Nitrous. Much above 20lbs (esp in the desert),
Goals:
(1) Flashing liquid to vapor to chill Nitrous is fine in a motor
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.
little more elegant and deterministic. Bags of ice aren't a great answer at
I know ice is a quick-and-dirty answer, but I would like something a
FAR or Blackrock.
Cold weather is no problem. I cannot prove what is happening, but I suspect
(2) I have had trouble igniting high density Nitrous in warm weather.
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.
the top and bottom of the rocket's oxidizer tank???
A related question: Any simple ways to equalize temperature between
electronics... ie Peltiers)
--MCS
(Im an EE kind of person so my solutions tend to feel like