Shawn,
You've got it right.
Pressure is indeed relatively low for nozzleless motors, but the key is
that the port area is quite large, at least in comparison to nozzled
motors. This is why nozzleless motors develop decent thrust.
Richard
On Mon, Jun 24, 2019 at 10:42 AM Shawn McHatten <shawn.mchatten@xxxxxxxxxxx>
wrote:
I'm wondering if I understand the formulas that are running around on this
thread. With the M19 burn the exit port diameter is approx 20mm or or a
port area of .62sq inches. And the thrust is approximately 40kg or 88
pounds at the beginning of the burn. Are we saying the pressure at that
point in the burn is 88lbs/.62sqin or about 140psi in the chamber. That
does not seem like a very high pressure at all. Sorry for mix and matching
units but I wanted to get it to something I understood.
thanks
Shawn
On Sat, Jun 22, 2019 at 2:48 PM <spas@xxxxxxxxx> wrote:
Richard,
There is no pressure on my graphs, I have not measured it. On the axes of
all my graphs - time in seconds and thrust in kilograms. 50,000 means 50
kg.
Sorry, some links are to AER group, it is only for subscribers.
Here are links on my FB page
https://www.facebook.com/serge.pipko.5/posts/480370956039788
https://www.facebook.com/serge.pipko.5/posts/450824292327788
Serge
Serge, what are the units of pressure, millibars? The video links seemdiameter
broken
Richard
On May 5, 2019 3:33 AM, <spas@xxxxxxxxx> wrote:
I began a series of tests of nozzleless motors of different
configurations
and with different propellants. The purpose of the tests is to find the
optimal configuration that will give the maximum Isp.
I recently tested 4 nozzleless motors with KNSB propellant. All motors
have the same size and weight, grain outer diameter 50 mm, core
19.3 mm, core length 500 mm, propellant mass 1500 g. Motors differ in
used
potassium nitrate.
M14 - granulated KNO3 (contains 0.8% SiO2 anticaking agent)
M15 - granulated KNO3 + 0,5% red iron oxide
M16 - pure milled KNO3
M17 - granulated milled KNO3
The following tests will be with a greater core length, with sodium
nitrate as an oxidizing agent and with the addition of aluminum.
Thrust curves of the motors are attached.
Videos of the tests can be seen here
https://www.facebook.com/groups/1396488870646273/
permalink/1993969987564822/
https://www.facebook.com/serge.pipko.5/posts/450824292327788
