Looks like China did a good job with their new engines on the LM5, the wiki
said that they transfered technology from Russia to make it happen. Didn't
the US have the same access to technology transfer from the Russians with
the RD 180 agreement? Anyway, kudos to China. ( I was surprised that nobody
commented about this launch as it is more than hrs ago)
On Nov 4, 2016 10:08 PM, "FreeLists Mailing List Manager" <
ecartis@xxxxxxxxxxxxx> wrote:
arocket Digest Fri, 04 Nov 2016 Volume: 04 Issue: 270
In This Issue:
[AR] Re: Pressure Thrust and Momentum Thrust
[AR] Re: N2O accident.
[AR] Re: LOX Test Stand Integration
[AR] Re: LOX Test Stand Integration
[AR] Re: LOX Test Stand Integration
[AR] Re: LOX Test Stand Integration
[AR] Alternate nozzle materials for APCP propellant
[AR] Re: N2O accident.
[AR] Re: LOX Test Stand Integration
[AR] Re: Alternate nozzle materials for APCP propellant
[AR] Re: Alternate nozzle materials for APCP propellant
[AR] Re: Alternate nozzle materials for APCP propellant
[AR] Re: Alternate nozzle materials for APCP propellant
[AR] Re: N2O accident.
[AR] Re: Alternate nozzle materials for APCP propellant
[AR] Re: Alternate nozzle materials for APCP propellant
[AR] Re: Alternate nozzle materials for APCP propellant
[AR] Re: {Spam?} Re: Pressure Thrust and Momentum Thrust
----------------------------------------------------------------------
From: Ian Woollard <ian.woollard@xxxxxxxxx>
Date: Fri, 4 Nov 2016 05:37:49 +0000
Subject: [AR] Re: Pressure Thrust and Momentum Thrust
On 2 November 2016 at 19:52, Norman Yarvin <yarvin@xxxxxxxxxxxx> wrote:
In any case, if purporting to explain something to me, you might deign
to actually address the main point I was making, namely that if one
takes the textbook equation and compares it under vacuum conditions to
the conservation of momentum, there's an extra term ("pressure
thrust") on one side of the textbook equation,
so the two equations disagree.
And when you take out the scales to judge credibility andUnfortunately our books can't do that either; which is the true shame here!
put all the rocket textbooks with that equation on one pan of the
scale and the conservation of momentum on the other, that resounding
"thunk" you hear is the conservation of momentum establishing its
authority and launching the textbooks past escape velocity.
I can’t recall seeing too much orange from the N2O mishaps that we’ve been
involved in on the test stand or launch rail, although they’re generally
pretty exciting times and it’s easy to overlook something like that.
I did experience what I suspect was a flashback event some years ago
(which resulted in some damage to our forklift) but unfortunately the guy
videoing it zoomed out just prior to the event and was also on the worst
possible angle with a glary sky in the background washing out just about
every detail. www.propulsionlabs.com.au/Misc_Video_And_Images/
Flashback1b.wmv
Troy
*From:* arocket-bounce@xxxxxxxxxxxxx [mailto:arocket-bounce@xxxxxxxxxxxxx]
*On Behalf Of *Paul Mueller
*Sent:* Friday, 4 November 2016 12:02 PM
*To:* arocket@xxxxxxxxxxxxx
*Subject:* {Spam?} [AR] Re: N2O accident.
I can't find anything on a more recent incident, but the one in Florida on
Aug 29 apparently caused an orange cloud (pics at
http://www.pnj.com/story/news/local/escambia-county/2016/08/
29/airgas-explosion-dock-accident/89537072/). Does this sound right for a
nitrous oxide explosion?
On Wed, Nov 2, 2016 at 6:22 PM, Daniel Dyck <daniel.dyck.379ba@xxxxxxxxx>
wrote:
Just wanted to make sure, I got confused by "last summer". If there was an
explosion, there aren't any news articles on it (as far as I can tell from
my google foo).
On Wed, Nov 2, 2016 at 5:16 PM, Anthony Cesaroni <acesaroni@xxxxxxxxxxx>
wrote:
Apparently but I can't confirm, hence the inquiry.
Anthony
Sent from my iPhone
On Nov 2, 2016, at 8:11 PM, Daniel Dyck <daniel.dyck.379ba@xxxxxxxxx>
wrote:
Your link is only a month old - are you saying there was another explosion
even more recent then that?
On Thu, Nov 3, 2016 at 9:36 PM, Graham Sortinoalthough
<dmarc-noreply@xxxxxxxxxxxxx <javascript:;>> wrote:
Tanks - For a simple LOX compatible tank I've seen 2 approaches (a)drill a
hole in the bottom of a steel gas's supplier tank and add fittings (this(b) cut
seems to be what Robert did
http://watzlavick.com/robert/rocket/rocket1/photos/dsc_1344m.jpg) or
off the bottom of the tank and weld the dome of another tank (this iswhat
the SEDS students at U Cal San Diego did http://www.sedsucsd.org/files/
static_fire_system_final_ report.pdf). I'm guessing (b) is better for
draining the LOX out of the bottom of the tank since its rounded
ofI'd prefer to use (a) because I do not have welding experience.
No, mild steel is not compatible with any cryogens. It becomes brittle
and could explode when pressurized or shatter when shocked. Stick with
aluminum, stainless steel, or brass. Robert's tanks are aluminum.
Insulation: Iinsulate all plumbing sections (including the tank) thathave
LOX into flowing through them. Are there any recommendations for types
theinsulation?
Any will work. Silicone insulation is less likely to disappear in a
somewhat energetic cloud than plastic foam. Cryogel is great but is
mildly flammable and is expensive. Pyrogel is the best but is
expensive to buy a roll.
If you use a fuel as insulation (styrofoam, spray foam, hardware store
pipe insulation) it's important that it not cover the fittings and
that none of the fittings leak.
LOX Propellant valve - it seems like most people are using an actuatedball
valve. A hole needs to be drilled upstream in the valve to let trappedLOX
escape. I could not find any good pictures of where this hole should beso
if anyone has any references I'd appreciate it? It also seems like inmany
In the upstream face of the ball, centered in the port when the valve
is closed. It also needs to be well deburred and fillleted or it will
tear up the seal.
cases seals need to replaced in order for them to work effectively but Ihad
trouble finding best practices for this. My understanding is that thePTFE
shrinks more than the metal at cryo temperatures which causes gaps in
ofseals and possibly a spring energized seals can help here. Also, I was
hoping to start with off the shelf cryo valves to minimize the chances
ofaccidents but I've been having trouble finding references of valvespeople
You can google cryogenic ball valve and find suppliers. Expect to
spend around $1k for a specifically cryogenic ball valve with a
pneumatic actuator.
have used in the archives except for Robert's re-built Swagelok SS-62T6,(Thursday,
which is probably more than I need because it doesn't have to be flight
weight. I did find one reference to the SDSU students using this valve
http://www.mcmaster.com/#4632k144/=wvcozg from a posting dated
April 23, 2015 12:21 PM) but the post suggested there were potentiallymany
problems with the valve leaking.
Other Cryo Valves (eg. Vent, purge and fill valves) - I didn't find as
references to choices people made in this area but if there are anyon
suggestions for valves to get started with I'd appreciate it.
Fittings: Do not use NPT fittings with LOX except where unavoidable (eg.
vavle fittings) because the PTFE thread tape can get into the plumbingand
create a safety/fire hazard. instead only use AN fittings without thread
tape.
Meh. I'm not as anti-NPT as some people here. I've used a lot of it
with success. Flushing out the system is a good idea. PTFE shreds in
LOX will not do anything too scary, it's mostly an annoyance of them
plugging orifices like in igniters or injectors.
Any valve with all LOX compatible materials that has been cleaned for
oxidizer service is LOX compatible until proven otherwise. It should
not be surprising that companies who have found success with non-cryo
valves in cryo use haven't shared all the details, since it does
represent hard fought experimental knowledge.
Seals and Lubricant: All seals must be PTFE and use Krytox to lubricate
valves/seals.
Don't lubricate valves at all. Krytox is LOX compatible, meaning it
won't explode, but it'll still freeze. PTFE is solid lubricant, in a
ball valve there's not really any significant metal on metal movement.
N2 vs LOX: if I start w/ N2 and switch to LOX do I need to buy all new
plumbing or can I clean the N2 plumbing and re-use it for LOX assuming
course it is LOX compatible.
You can clean it. You can also take it apart and send it to an
oxidizer cleaning shop.
Anything else that you feel is relevant?
So much. You're off to a good start, but there's a big knowledge base
to gain. As I suggested to the last person who asked on list about
this topic, you really should go to a FAR weekend on one when someone
is running a project with LOX, so you can see what people are doing
and hopefully see things you don't understand.
still
Finally, I haven't picked a chamber pressure yet for my engine as I'm
researching options but I'd say it would almost certainly be between 250and
500 psia. All work will be done on my test stand so nothing needs to bemore
flight weight.
I'm still very much in the early planning phases and I'm sure I'll have
questions as I go through but any advice of course is very muchappreciated.
Kind Regards,
Graham
is closed. It also needs to be well deburred and fillleted or it will“In the upstream face of the ball, centered in the port when the valve
spend around $1k for a specifically cryogenic ball valve with aYou can google cryogenic ball valve and find suppliers. Expect to
non-cryoIt should not be surprising that companies who have found success with
ball valve and add a rotary or linear actuator to it.For your test stand, find a surplus 1/2 or 3/4 inch Worcester cryogenic
won't explode, but it'll still freeze. PTFE is solid lubricant, in aDon't lubricate valves at all. Krytox is LOX compatible, meaning it
this topic, you really should go to a FAR weekend on one when someoneAs I suggested to the last person who asked on list about
the story again about finding a glob of grease in my LOX tank after fillingIn theory, the LN2 should be as clean as the LOX but I have to relate
Tanks - For a simple LOX compatible tank I've seen 2 approaches (a) drilla
hole in the bottom of a steel gas's supplier tank and add fittings (this(b) cut
seems to be what Robert did
http://watzlavick.com/robert/ rocket/rocket1/photos/dsc_ 1344m.jpg) or
off the bottom of the tank and weld the dome of another tank (this is what
the SEDS students at U Cal San Diego did http://www.sedsucsd.org/files/
static_fire_system_final_ report.pdf). I'm guessing (b) is better for
draining the LOX out of the bottom of the tank since its rounded although
I'd prefer to use (a) because I do not have welding experience.
Insulation: Iinsulate all plumbing sections (including the tank) that have
LOX into flowing through them. Are there any recommendations for types of
insulation?
LOX Propellant valve - it seems like most people are using an actuatedball
valve. A hole needs to be drilled upstream in the valve to let trapped LOX
escape. I could not find any good pictures of where this hole should be so
if anyone has any references I'd appreciate it? It also seems like in many
cases seals need to replaced in order for them to work effectively but Ihad
trouble finding best practices for this. My understanding is that the PTFE
shrinks more than the metal at cryo temperatures which causes gaps in the
seals and possibly a spring energized seals can help here. Also, I was
hoping to start with off the shelf cryo valves to minimize the chances of
accidents but I've been having trouble finding references of valves people
have used in the archives except for Robert's re-built Swagelok SS-62T6,many
which is probably more than I need because it doesn't have to be flight
weight. I did find one reference to the SDSU students using this valve
http://www.mcmaster.com/# 4632k144/=wvcozg from a posting dated ;(Thursday,
April 23, 2015 12:21 PM) but the post suggested there were potentially
problems with the valve leaking.
Other Cryo Valves (eg. Vent, purge and fill valves) - I didn't find as
references to choices people made in this area but if there are anyon
suggestions for valves to get started with I'd appreciate it.
Fittings: Do not use NPT fittings with LOX except where unavoidable (eg.
vavle fittings) because the PTFE thread tape can get into the plumbing and
create a safety/fire hazard. instead only use AN fittings without thread
tape.
Seals and Lubricant: All seals must be PTFE and use Krytox to lubricate
valves/seals.
N2 vs LOX: if I start w/ N2 and switch to LOX do I need to buy all new
plumbing or can I clean the N2 plumbing and re-use it for LOX assuming of
course it is LOX compatible.
Anything else that you feel is relevant?
still
Finally, I haven't picked a chamber pressure yet for my engine as I'm
researching options but I'd say it would almost certainly be between 250and
500 psia. All work will be done on my test stand so nothing needs to bemore
flight weight.
I'm still very much in the early planning phases and I'm sure I'll have
questions as I go through but any advice of course is very muchappreciated.
Kind Regards,
Graham
Ball Valve Vent*
is closed. It also needs to be well deburred and fillleted or it will“In the upstream face of the ball, centered in the port when the valve
tear up the seal.”<<
Just to clarify does this mean the hole is drilled in the actual ball? I
had thought from reading other’s posts that the parts were first removed
the valve and then a hole was drilled in the valve body? If possible, a
picture would be very helpful.
*non-cryo
Vendors*
spend around $1k for a specifically cryogenic ball valve with aYou can google cryogenic ball valve and find suppliers. Expect to
pneumatic actuator.<<
Thanks & understood. I was thinking of using a servo actuated valve and
building the housing for this myself. That is what I did for my non-cryo
valves and it worked well although they were plug style valves rather
than ball.
It should not be surprising that companies who have found success with
valves in cryo use haven't shared all the details, since it doescryogenic ball valve and add a rotary or linear actuator to it.
represent hard fought experimental knowledge.<<
Thanks for explaining I hadn’t considered this but of course I
understand the rationale. I was hoping to using something like a
Swagelok valve which I’ve used in the past and like them quite a bit but
since safety is more of a concern than cost or weight I wouldn’t want to
do this unless others had at least a reasonable amount of success here.
I thought maybe some of the academic teams or their mentors who are on
the list might be able to provide some suggestions since its less of a
trade secret.
For your test stand, find a surplus 1/2 or 3/4 inch Worcester
Thanks Bob, I think I saw someone post about Worcester valves before and
mentioning they were good but quite pricey. I will keep an eye out.
*Krytox*
won't explode, but it'll still freeze. PTFE is solid lubricant, in aDon't lubricate valves at all. Krytox is LOX compatible, meaning it
ball valve there's not really any significant metal on metal movement.<<
I see your point but I’m a bit confused by this because there was a post
from Carl on Thursday, April 23, 2015 12:21 PM regarding the team he
mentors where he says “We are using a COTS 3-piece ball valve… To modify
it for use as a cryo-valve we disassemble it and clean it, drill a vent
hole in the ball to vent out trapped LOX, and re-lube it with a light
coating of Krytox.”
wrote:
On 11/4/2016 5:52 AM, Graham Sortino (Redacted sender gnsortino for DMARC)the
wrote:
Ball Valve Vent*
“In the upstream face of the ball, centered in the port when the valvetear up the seal.”<<
is closed. It also needs to be well deburred and fillleted or it will
Just to clarify does this mean the hole is drilled in the actual ball? I
had thought from reading other’s posts that the parts were first removed
the valve and then a hole was drilled in the valve body? If possible, a
picture would be very helpful.
The problem being solved is this: When you close a cryo ball valve, the
cylindrical passage through the ball still contains a slug of cryo fluid.
Once closed, that cryo slug is trapped inside the ball by the valve body
sides and the ball seals. If the cryo fluid slug is left there as the
system warms, overpressures will result. Bang! as the seals, valve body,
or both let go...
The standard solution to this is indeed a hole drilled through the
when-closed upstream center of the ball, so the ball-passage contents are
no longer trapped, but rather can feed back into the upstream cryo feed
system, thus presumably being handled in the same manner as the rest of
feed system's contents.do
One major reason why this is traditional is the way the ball seals work.
Given a high-pressure and low-pressure end of the valve (and if not, why
you need a valve?) the ball will be pressed more firmly into the seal onless
the low-pressure end. The seal on the high-pressure end thus may seal
reliably. Since venting the ball passage also vents the valve-bodybetween
the seals, venting the ball to the downstream (low-pressure) end risks abe
steady leak past the upstream seal, into the valve body, into the ball
passage, and out the ball vent. (Venting the valve body itself would
present the same problem.)
*
Vendors*
You can google cryogenic ball valve and find suppliers. Expect topneumatic actuator.<<
spend around $1k for a specifically cryogenic ball valve with a
Thanks & understood. I was thinking of using a servo actuated valve and
building the housing for this myself. That is what I did for my non-cryo
valves and it worked well although they were plug style valves rather
than ball.
It should not be surprising that companies who have found success with
represent hard fought experimental knowledge.<<non-cryovalves in cryo use haven't shared all the details, since it does
Thanks for explaining I hadn’t considered this but of course I
understand the rationale. I was hoping to using something like a
Swagelok valve which I’ve used in the past and like them quite a bit but
since safety is more of a concern than cost or weight I wouldn’t want to
do this unless others had at least a reasonable amount of success here.
I thought maybe some of the academic teams or their mentors who are on
the list might be able to provide some suggestions since its less of a
trade secret.
For your test stand, find a surplus 1/2 or 3/4 inch Worcester
cryogenic ball valve and add a rotary or linear actuator to it.
Thanks Bob, I think I saw someone post about Worcester valves before and
mentioning they were good but quite pricey. I will keep an eye out.
Two things to keep an eye on here: LOX-compatible materials - brass,
aluminum, or the proper stainless types - and cryo-rated *LOX-compatible*
seals. Generally these will be some flavor of PTFE. You want to be very
careful about seal LOX-compatibility in using non-cryo valves. It would
a safe guess that successful use of non-cryo valves in cryo apps involves
both making sure the valve materials are cryo-capable and replacing the
seals with cryo seals.
*Krytox*
Don't lubricate valves at all. Krytox is LOX compatible, meaning itball valve there's not really any significant metal on metal movement.<<
won't explode, but it'll still freeze. PTFE is solid lubricant, in a
I see your point but I’m a bit confused by this because there was a post
from Carl on Thursday, April 23, 2015 12:21 PM regarding the team he
mentors where he says “We are using a COTS 3-piece ball valve… To modify
it for use as a cryo-valve we disassemble it and clean it, drill a vent
hole in the ball to vent out trapped LOX, and re-lube it with a light
coating of Krytox.”
I can testify that Krytox does in fact freeze solid well before cryo
temps. Speculative: The "light coating" in this instance ends up being a
thin solid film under cryo conditions, thin enough and/or strategically
enough placed that it doesn't immobilize the valve. Non-speculative: They
are not including near enough details here to safely duplicate their
application.
Henry
I can't find anything on a more recent incident, but the one in29/airgas-explosion-dock-accident/89537072/).
Florida on Aug 29 apparently caused an orange cloud (pics at
http://www.pnj.com/story/news/local/escambia-county/2016/08/
Does this sound right for a nitrous oxide explosion?
On Wed, Nov 2, 2016 at 6:22 PM, Daniel Dyck
<daniel.dyck.379ba@xxxxxxxxx <mailto:daniel.dyck.379ba@xxxxxxxxx>> wrote:
Just wanted to make sure, I got confused by "last summer". If
there was an explosion, there aren't any news articles on it (as
far as I can tell from my google foo).
On Wed, Nov 2, 2016 at 5:16 PM, Anthony Cesaroni
<acesaroni@xxxxxxxxxxx <mailto:acesaroni@xxxxxxxxxxx>> wrote:
Apparently but I can't confirm, hence the inquiry.
Anthony
Sent from my iPhone
On Nov 2, 2016, at 8:11 PM, Daniel Dyck
<daniel.dyck.379ba@xxxxxxxxx
<mailto:daniel.dyck.379ba@xxxxxxxxx>> wrote:
Your link is only a month old - are you saying there was
another explosion even more recent then that?
Is this what you're describing?Yes.
Does this create the same problem in the reverse situation? i.e: When
the ball valve is open you could have a LOX slug stuck in the ball?
On Fri, Nov 4, 2016 at 9:02 AM, Henry Vanderbilt
<hvanderbilt@xxxxxxxxxxxxxx <mailto:hvanderbilt@xxxxxxxxxxxxxx>> wrote:
On 11/4/2016 5:52 AM, Graham Sortino (Redacted sender gnsortino
for DMARC) wrote:
Ball Valve Vent*
“In the upstream face of the ball, centered in the
port when the valve
is closed. It also needs to be well deburred and fillleted or
it will
tear up the seal.”<<
Just to clarify does this mean the hole is drilled in the
actual ball? I
had thought from reading other’s posts that the parts were
first removed
the valve and then a hole was drilled in the valve body? If
possible, a
picture would be very helpful.
The problem being solved is this: When you close a cryo ball
valve, the cylindrical passage through the ball still contains a
slug of cryo fluid. Once closed, that cryo slug is trapped inside
the ball by the valve body sides and the ball seals. If the cryo
fluid slug is left there as the system warms, overpressures will
result. Bang! as the seals, valve body, or both let go...
The standard solution to this is indeed a hole drilled through the
when-closed upstream center of the ball, so the ball-passage
contents are no longer trapped, but rather can feed back into the
upstream cryo feed system, thus presumably being handled in the
same manner as the rest of the feed system's contents.
One major reason why this is traditional is the way the ball seals
work. Given a high-pressure and low-pressure end of the valve
(and if not, why do you need a valve?) the ball will be pressed
more firmly into the seal on the low-pressure end. The seal on
the high-pressure end thus may seal less reliably. Since venting
the ball passage also vents the valve-body between the seals,
venting the ball to the downstream (low-pressure) end risks a
steady leak past the upstream seal, into the valve body, into the
ball passage, and out the ball vent. (Venting the valve body
itself would present the same problem.)
*
Vendors*
You can google cryogenic ball valve and find
suppliers. Expect to
spend around $1k for a specifically cryogenic ball valve with a
pneumatic actuator.<<
Thanks & understood. I was thinking of using a servo actuated
valve and
building the housing for this myself. That is what I did for
my non-cryo
valves and it worked well although they were plug style valves
rather
than ball.
It should not be surprising that companies who have
found success with non-cryo
valves in cryo use haven't shared all the details, since it does
represent hard fought experimental knowledge.<<
Thanks for explaining I hadn’t considered this but of course I
understand the rationale. I was hoping to using something like a
Swagelok valve which I’ve used in the past and like them quite
a bit but
since safety is more of a concern than cost or weight I
wouldn’t want to
do this unless others had at least a reasonable amount of
success here.
I thought maybe some of the academic teams or their mentors
who are on
the list might be able to provide some suggestions since its
less of a
trade secret.
For your test stand, find a surplus 1/2 or 3/4 inch
Worcester
cryogenic ball valve and add a rotary or linear actuator to it.
Thanks Bob, I think I saw someone post about Worcester valves
before and
mentioning they were good but quite pricey. I will keep an eye
out.
Two things to keep an eye on here: LOX-compatible materials -
brass, aluminum, or the proper stainless types - and cryo-rated
*LOX-compatible* seals. Generally these will be some flavor of
PTFE. You want to be very careful about seal LOX-compatibility in
using non-cryo valves. It would be a safe guess that successful
use of non-cryo valves in cryo apps involves both making sure the
valve materials are cryo-capable and replacing the seals with cryo
seals.
*Krytox*
Don't lubricate valves at all. Krytox is LOX
compatible, meaning it
won't explode, but it'll still freeze. PTFE is solid
lubricant, in a
ball valve there's not really any significant metal on metal
movement.<<
I see your point but I’m a bit confused by this because there
was a post
from Carl on Thursday, April 23, 2015 12:21 PM regarding the
team he
mentors where he says “We are using a COTS 3-piece ball valve…
To modify
it for use as a cryo-valve we disassemble it and clean it,
drill a vent
hole in the ball to vent out trapped LOX, and re-lube it with
a light
coating of Krytox.”
I can testify that Krytox does in fact freeze solid well before
cryo temps. Speculative: The "light coating" in this instance
ends up being a thin solid film under cryo conditions, thin enough
and/or strategically enough placed that it doesn't immobilize the
valve. Non-speculative: They are not including near enough details
here to safely duplicate their application.
Henry
Looking at alternate materials for a long burn motor design that haveRight
lower thermal conductivity and heat capacity as compared to graphite.
now I'm considering machinable ceramics, BN, and perhaps molded alumina.
Any personal experience or publication links would be most welcome.
John
Looking at alternate materials for a long burn motor design that have--
lower thermal conductivity and heat capacity as compared to graphite.
Right now I'm considering machinable ceramics, BN, and perhaps molded
alumina. Any personal experience or publication links would be most
welcome.
John
Hi John,problem.
Years ago I molded small nozzles using Firefox's carbospheres and Weldwood
phenolic adhesive. They worked well enough to warrant further attempts.
They did erode somewhat, and the adhesive cured rather quickly and shrank
significantly; they should be cured under pressure to minimize that
Right
Weldwood apparently isn't available anymore but Cascophen seems to be the
same sort of product:
http://www.aircraftspruce.com/catalog/wppages/cascophen.php
Best -- Terry
On 11/4/2016 11:34 AM, John Lyngdal wrote:
Looking at alternate materials for a long burn motor design that have
lower thermal conductivity and heat capacity as compared to graphite.
now I'm considering machinable ceramics, BN, and perhaps molded alumina.Dr. Terry McCreary
Any personal experience or publication links would be most welcome.
John
--
Professor of Chemistry
Murray State University
Murray KY 42071
Gents,15mm
A favorite topic of mine. Some ideas:
1. I saw one nozzle that was made from a hunk of phenolic (?) cloth tube
with a graphite throat insert. It certainly seemed like the best of both
worlds.
2. Graphite does dump so much heat to the casing. The idea mentioned of an
insulating band between it and the wall is worth looking at.
3. I just bought some carbon fiber washers that might make nice throat
inserts. They come in all sorts of sizes. The ones I got were 28mm OD,
hole, 2.5mm thick. Here's a link:sale?Thanks.
http://www.ebay.com/itm/201625351883?_trksid=p2060353.
m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
4. Firefox provides some nice insulation material. My favorite is their
graphite impregnated cloth. I use it a lot; line bulkheads, make custom
casting/liner tubes for propellant grains, etc. I'd thought of trying to
make nozzles with the carbon cloth as the main element. Haven't moved past
the thought stage yet.
On another topic. I could really use a strand burner and am not having
much luck making one. Does anyone know of one that might be for
Right
Cheers,
Brian
On Fri, Nov 4, 2016 at 12:45 PM, Terry McCreary <tmccreary@xxxxxxxxxxxxxxx
<javascript:_e(%7B%7D,'cvml','tmccreary@xxxxxxxxxxxxxxx');>> wrote:
Hi John,
Years ago I molded small nozzles using Firefox's carbospheres and
Weldwood phenolic adhesive. They worked well enough to warrant further
attempts. They did erode somewhat, and the adhesive cured rather quickly
and shrank significantly; they should be cured under pressure to minimize
that problem.
Weldwood apparently isn't available anymore but Cascophen seems to be the
same sort of product:
http://www.aircraftspruce.com/catalog/wppages/cascophen.php
Best -- Terry
On 11/4/2016 11:34 AM, John Lyngdal wrote:
Looking at alternate materials for a long burn motor design that have
lower thermal conductivity and heat capacity as compared to graphite.
now I'm considering machinable ceramics, BN, and perhaps molded alumina.Dr. Terry McCreary
Any personal experience or publication links would be most welcome.
John
--
Professor of Chemistry
Murray State University
Murray KY 42071
Is there an off the shelf adhesive for gluing graphite to stuff that isn'tplates
terrible? I remember Armadillo bought some stuff for gluing graphite
to concrete, but they said it was super expensive and 5 gallon quantity.15mm
On Friday, November 4, 2016, BrianK ABQ <cielobenazul@xxxxxxxxx
<javascript:_e(%7B%7D,'cvml','cielobenazul@xxxxxxxxx');>> wrote:
Gents,
A favorite topic of mine. Some ideas:
1. I saw one nozzle that was made from a hunk of phenolic (?) cloth tube
with a graphite throat insert. It certainly seemed like the best of both
worlds.
2. Graphite does dump so much heat to the casing. The idea mentioned of
an insulating band between it and the wall is worth looking at.
3. I just bought some carbon fiber washers that might make nice throat
inserts. They come in all sorts of sizes. The ones I got were 28mm OD,
pasthole, 2.5mm thick. Here's a link:
http://www.ebay.com/itm/201625351883?_trksid=p2060353.m2749.
l2649&ssPageName=STRK%3AMEBIDX%3AIT
4. Firefox provides some nice insulation material. My favorite is their
graphite impregnated cloth. I use it a lot; line bulkheads, make custom
casting/liner tubes for propellant grains, etc. I'd thought of trying to
make nozzles with the carbon cloth as the main element. Haven't moved
sale?Thanks.the thought stage yet.
On another topic. I could really use a strand burner and am not having
much luck making one. Does anyone know of one that might be for
quickly
Cheers,
Brian
On Fri, Nov 4, 2016 at 12:45 PM, Terry McCreary <
tmccreary@xxxxxxxxxxxxxxx> wrote:
Hi John,
Years ago I molded small nozzles using Firefox's carbospheres and
Weldwood phenolic adhesive. They worked well enough to warrant further
attempts. They did erode somewhat, and the adhesive cured rather
minimizeand shrank significantly; they should be cured under pressure to
Rightthat problem.
Weldwood apparently isn't available anymore but Cascophen seems to be
the same sort of product:
http://www.aircraftspruce.com/catalog/wppages/cascophen.php
Best -- Terry
On 11/4/2016 11:34 AM, John Lyngdal wrote:
Looking at alternate materials for a long burn motor design that have
lower thermal conductivity and heat capacity as compared to graphite.
alumina.now I'm considering machinable ceramics, BN, and perhaps molded
Any personal experience or publication links would be most welcome.Dr. Terry McCreary
John
--
Professor of Chemistry
Murray State University
Murray KY 42071
Cotronics makes a relatively inexpensive graphite adhesive/sealant that’sof
good to well over 5000 F. Taper the OD of the graphite throat and the ID
the nozzle convergent section to for a positive taper lock. Coat both15mm
surfaces, drop it in and heat cure it. Standard industrial practice.
Best.
Anthony J. Cesaroni
President/CEO
Cesaroni Technology/Cesaroni Aerospace
http://www.cesaronitech.com/
(941) 360-3100 x101 Sarasota
(905) 887-2370 x222 Toronto
*From:* arocket-bounce@xxxxxxxxxxxxx
<javascript:_e(%7B%7D,'cvml','arocket-bounce@xxxxxxxxxxxxx');> [mailto:
arocket-bounce@xxxxxxxxxxxxx
<javascript:_e(%7B%7D,'cvml','arocket-bounce@xxxxxxxxxxxxx');>] *On
Behalf Of *BrianK ABQ
*Sent:* Friday, November 4, 2016 6:30 PM
*To:* arocket@xxxxxxxxxxxxx
<javascript:_e(%7B%7D,'cvml','arocket@xxxxxxxxxxxxx');>
*Subject:* [AR] Re: Alternate nozzle materials for APCP propellant
Gents,
A favorite topic of mine. Some ideas:
1. I saw one nozzle that was made from a hunk of phenolic (?) cloth tube
with a graphite throat insert. It certainly seemed like the best of both
worlds.
2. Graphite does dump so much heat to the casing. The idea mentioned of an
insulating band between it and the wall is worth looking at.
3. I just bought some carbon fiber washers that might make nice throat
inserts. They come in all sorts of sizes. The ones I got were 28mm OD,
hole, 2.5mm thick. Here's a link:sale?Thanks.
http://www.ebay.com/itm/201625351883?_trksid=p2060353.
m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT
4. Firefox provides some nice insulation material. My favorite is their
graphite impregnated cloth. I use it a lot; line bulkheads, make custom
casting/liner tubes for propellant grains, etc. I'd thought of trying to
make nozzles with the carbon cloth as the main element. Haven't moved past
the thought stage yet.
On another topic. I could really use a strand burner and am not having
much luck making one. Does anyone know of one that might be for
problem.
Cheers,
Brian
On Fri, Nov 4, 2016 at 12:45 PM, Terry McCreary <tmccreary@xxxxxxxxxxxxxxx
<javascript:_e(%7B%7D,'cvml','tmccreary@xxxxxxxxxxxxxxx');>> wrote:
Hi John,
Years ago I molded small nozzles using Firefox's carbospheres and Weldwood
phenolic adhesive. They worked well enough to warrant further attempts.
They did erode somewhat, and the adhesive cured rather quickly and shrank
significantly; they should be cured under pressure to minimize that
Right
Weldwood apparently isn't available anymore but Cascophen seems to be the
same sort of product:
http://www.aircraftspruce.com/catalog/wppages/cascophen.php
Best -- Terry
On 11/4/2016 11:34 AM, John Lyngdal wrote:
Looking at alternate materials for a long burn motor design that have
lower thermal conductivity and heat capacity as compared to graphite.
now I'm considering machinable ceramics, BN, and perhaps molded alumina.
Any personal experience or publication links would be most welcome.
John
--
Dr. Terry McCreary
Professor of Chemistry
Murray State University
Murray KY 42071
less confusing
All that's fine enough, as far as it goes. (Your model is certainly
accounts forthan the one in the textbook.) But I think this "pressure thrust"
force on100% of the thrust in this scenario -- because where would any other
momentumthe cylinder come from? Yet in this scenario there's still plenty of
"pressure thrust"being created: the gas is shooting out fast. So if you take this
Likewise,and add the thrust from momentum to it, you'd be double counting.
if you calculate the momentum of the exhaust gases and compute the thrust
that way, you shouldn't add the "pressure thrust" to it.
Yup, good points.
theIn any case, if purporting to explain something to me, you might deign to
actually address the main point I was making, namely that if one takes
disagree.textbook equation and compares it under vacuum conditions to the
conservation of momentum, there's an extra term ("pressure
thrust") on one side of the textbook equation, so the two equations
rocketAnd when you take out the scales to judge credibility and put all the
conservation oftextbooks with that equation on one pan of the scale and the
conservationmomentum on the other, that resounding "thunk" you hear is the
of momentum establishing its authority and launching the textbooks past
escape velocity.
This is where I disagree because of the above point I just
made. Thrust is *fundamentally* derived from *pressure* not momentum.
