Absolutely, but when it is happening too far up we lose stability and spit
important motor chunks.
Tapered core should push the choke point closer to the tail.
I'm not currently equipped to perform validation, but it should be
relatively straightforward to have two nozless motors with the same length
and diameter, both having the same volume of propellant, one with an
overchoked cylinderical core and the other with an equal-volume tapered
core that exhibits no chunking.
On Tue, Jun 25, 2019, 9:01 AM <spas@xxxxxxxxx> wrote:
I believe it is relevant to long motor cores of any type ; it relieves
symptoms of erosive burning.
Yes, tapered core prevents erosive burning in nozzled motors.
But in nozzleless motor erosive burning is not a bug, it is natural
behavior. How can we have a sonic choke in bare propellant and don't
have
erosive burning in this place and up the core?
Serge
with
My suspicion is with nozless the taper can be much more gradual than
stepped batesto
As an added bonus, it should make the casting core easier to remove.
On Tue, Jun 25, 2019, 12:59 AM <spas@xxxxxxxxx> wrote:
Why we need increase core toward the end?
Where this knowledge come from? Is it relevant to nozzled motors or
knownozzleless motors?
Serge
Why are we continuing to make longer pure straight cores, when we
seethat
we need to gradually increase the core toward the end ? Just to
ignitionwhere
the upper limit is for various propellant flavors?wrote:
On Mon, Jun 24, 2019 at 12:17 PM Alex Kuehn <awkpilot@xxxxxxxxx>
The pressure in these motors is pretty low but the thrust at
seeis
very impressive.
https://youtu.be/fQs2THUi2Cc
That is a 24mm G I made that is nozzleless.
Some of us are working on trying to push the limits of these and
do ahow
correctlymuch performance we can get without a nozzle.
My typical nozzleless motor has a 1:32 core which if I recall
is
an initial Kn of 129.
I am working with a gentleman from Washington (Richard Miles) to
initialseries of tests to see how long we can make a motor but our
be atests
have shown it gets a lot less straightforward (irregular burning,
errosive
burning, etc) when you try to do a really long one even though the
calculations seem to support doing one's that are longer than what
people
have down so far.
https://youtu.be/ZGpuR5dLRBM
This is a video of a motor test we did that I'd calculated would
for29mm
H254 using Richard Nakkas propellant data and my excel calculator
(thenozzleless motors and we got it to go finally and hold together
infirst
tests at this length ejected chunks of propellant) by lighting it
grainthe
middle rather than the head of the grain but the friction fit
humiditysoonwasn't
secure enough and it failed. We're going to continue this testing
hopefully but both Richard Miles and myself have issues with
weand
propellant where we live so we're both waiting on rain to stop so
aroundcan
continue testing.
-Alex
On Mon, Jun 24, 2019, 10:42 AM Shawn McHatten
<shawn.mchatten@xxxxxxxxxxx>
wrote:
I'm wondering if I understand the formulas that are running
20mmon
this thread. With the M19 burn the exit port diameter is approx
oror
or
a port area of .62sq inches. And the thrust is approximately 40kg
at88
pounds at the beginning of the burn. Are we saying the pressure
chamber.that
point in the burn is 88lbs/.62sqin or about 140psi in the
theThat
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
linksaxes
meansof
all my graphs - time in seconds and thrust in kilograms. 50,000
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
toseem
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
Allfind
the
optimal configuration that will give the maximum Isp.
I recently tested 4 nozzleless motors with KNSB propellant.
coremotors
have the same size and weight, grain outer diameter 50 mm,
aluminum.differdiameter
19.3 mm, core length 500 mm, propellant mass 1500 g. Motors
sodiumin
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
nitrate as an oxidizing agent and with the addition of
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