And further (with solids this time):
2 tests – same casing/nozzle/hardware, very similar (AP+PPG composite
propellant) with the only subtle difference being that one had some cupric
oxide added (~0.5%) that was more for plume colouring than burn rate
modification. Similar thrust profiles but completely different plumage.
www.propulsionlabs.com.au/Misc_Video_And_Images/Test4_at_Full_Thrust.jpg
<http://www.propulsionlabs.com.au/Misc_Video_And_Images/Test4_at_Full_Thrust.jpg>
www.propulsionlabs.com.au/Misc_Video_And_Images/Test5_at_Full_Thrust.jpg
<http://www.propulsionlabs.com.au/Misc_Video_And_Images/Test5_at_Full_Thrust.jpg>
One producing a more transparent plume with a series of mach diamonds and the
other a more opaque incandescent plume with perhaps an initial shock signature
but nothing beyond.
Troy
From: arocket-bounce@xxxxxxxxxxxxx [mailto:arocket-bounce@xxxxxxxxxxxxx] On ;
Behalf Of Troy Prideaux
Sent: Tuesday, 9 February 2021 9:17 AM
To: arocket@xxxxxxxxxxxxx
Subject: [AR] Re: Math and specifics of hybrid nitrous.
Yes, I can’t recall seeing mach diamonds on small scale (say <10000N) N2O
*HTPB* hybrids either which doesn’t suggest they’re impossible to produce with
the right mixture ratio, pressure ratio, expansion ratio and operating
conditions, but it’s definitely easier to produce them with some fuels rather
than others.
As I said, I have seen them produced in larger scale with N2O:HTPB
combination such as:
https://spaceflightnow.com/2018/04/05/virgin-galactic-completes-first-rocket-powered-test-flight-since-2014/
but even on that scale it’s rare to see them with that combination.
Troy
From: arocket-bounce@xxxxxxxxxxxxx <mailto:arocket-bounce@xxxxxxxxxxxxx>
[mailto:arocket-bounce@xxxxxxxxxxxxx] On Behalf Of Paul Mueller
Sent: Tuesday, 9 February 2021 8:49 AM
To: arocket@xxxxxxxxxxxxx <mailto:arocket@xxxxxxxxxxxxx>
Subject: [AR] Re: Math and specifics of hybrid nitrous.
Yes, 20 psig chamber pressure at sea level.
After I wrote that I hadn't seen mach diamonds in a hybrid I recalled one that
we made with sugar fuel (like rock candy but with no oxidizer) produced a clear
flame with distinct mach diamonds. My bad...I should have said HTPB hybrids
On Sun, Jan 24, 2021 at 7:40 PM roxanna Mason <rocketmaster.ken@xxxxxxxxx
<mailto:rocketmaster.ken@xxxxxxxxx> > wrote:
But if your 20 psi is in gauge then Pc is 34.7 PSIA which is greater than 2/1
pressure ratio, sufficient for choked flow and shock diamonds which aren't
always visible if the plume is obscured with smoke or luminous,etc.
K
On Sun, Jan 24, 2021 at 6:34 PM troy@xxxxxxxxxxxxxxxxxxxxx
<mailto:troy@xxxxxxxxxxxxxxxxxxxxx> <troy@xxxxxxxxxxxxxxxxxxxxx
<mailto:troy@xxxxxxxxxxxxxxxxxxxxx> > wrote:
You're right that you certainly don't need mach diamonds to verify choked or
even efficient flow. Saying that, I've seen plenty of nitrous hybrids produce
mach diamonds using a variety of fuels ie. Wax, PVC and some others on a small
(hobby) scale and HTPB & PE on larger scales.
Troy
Sent from my phone
-------- Original message --------
From: Paul Mueller <paul.mueller.iii@xxxxxxxxx
<mailto:paul.mueller.iii@xxxxxxxxx> >
Date: Mon, 25 Jan 2021, 12:53 pm
To: arocket@xxxxxxxxxxxxx <mailto:arocket@xxxxxxxxxxxxx>
Subject: [AR] Re: Math and specifics of hybrid nitrous.
Please correct me if I'm wrong but I think you can have choked flow through the
nozzle if the chamber pressure is only about 20 psig (at sea level). My
experience with hybrid motors is that the flame is opaque and I can't recall
ever seeing mach diamonds (in motors that had chamber pressures around 300-500
psig).
Paul
On Thu, Jan 21, 2021 at 8:17 PM Evan Daniel <evanbd@xxxxxxxxx
<mailto:evanbd@xxxxxxxxx> > wrote:
By far the simplest way to do this, in my opinion, is a relief valve
on your run tank. If you go this route, you'll also want a dump valve,
since your tank won't depressurize on its own.
Evan Daniel
On Thu, Jan 21, 2021 at 10:44 AM Edward Wranosky <edwardcw@xxxxxxxxx
<mailto:edwardcw@xxxxxxxxx> > wrote:
That is from Todd Moore - owner of Sky Ripper Systems.
Another piece of advice is to go the route that Mark (MCS) started and
temperature regulate your nitrous oxide. Remove ALL the variables you can.
Edward
On Wed, Jan 20, 2021 at 3:08 PM <mark.spiegl@xxxxxxxxx
<mailto:mark.spiegl@xxxxxxxxx> > wrote:
Jack Hanna wrote:
So, how to math?
Here's an N2O hybrid spread sheet if you want to play around with numbers to
get an instinct for what's likely to work. Sorry I cannot find the original
to properly credit the author:
http://www.spiegl.org/rocket02/HDASv1.6.xls
--MCS
