Motor Casing Grease

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DMcCauley

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Vaseline baby!

I use it up to M reloads with no problems. But as was said, it does get a bit runny when it gets warmer.
 

Luv2launch

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Vaseline does work; lots of us (including me) have used it.

My primary reason for moving away from it initially is that it liquifies at such a low temperature, causing it to get everywhere you don't necessarily want it.

-Kevin
Yes it does get pretty runny sitting in a range box on a hot day that happened to me last year at a launch I forgot to put it in the cooler when I got there and it almost spilled all over my lap when I open up the jar.Still did its job though I only really use it on the O rings and threads.
 

Davidtmp

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It basically comes down to products that are made for the job at hand and products that are made for other purposes that will work. Most rocket builders are GREAT at using products other than what they are made for. Personally, I am going to find some of the Slick 50. If I get in a pinch and need something quick, I am glad to know I CAN use vasoline with good success. Never know when you may forget to get out to buy more grease.
 

Diosces

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Vaseline does work; lots of us (including me) have used it.

My primary reason for moving away from it initially is that it liquifies at such a low temperature, causing it to get everywhere you don't necessarily want it.

-Kevin
Exactly why I would not use vaseline. It is an inferior product for the application we are discussing. It's not engineered for high temp applications-- loses it's stiffnesss/viscosity even at high ambient temperatures. This can result in it going where it's not supposed to be, etc.

Here's an excerpt from RCS Web Archive regarding lubricants:

2/18/05
RCS Distributing Synco™ Super-Lube™ Synthetic O-Ring Grease
RCS is now an authorized distributor for Synco Super-Lube synthetic o-ring grease. Over the years, Super-Lube has proven to be the best o-ring lubricant for all types of reloadable rocket motors, and is specifically recommended for use with the AeroTech RMS™ Reloadable Motor System™. It is easy to clean up and does not inhibit the adhesion of masking tape as some other greases are prone to do. RCS is offering Super-Lube grease in three sizes: a 1 cc packet, a 3 oz. tube and a 400 gram can.

I'd be curious how well vaseline actually works and what the ratio of motor failures occur when comparing types of lubricant that were used. Not sure that there's much statistical data out there though..

Again, saving a few nickels using an inferior lubricant in a rocket motor seems the poster child for penny-wise and dollar foolish.
 
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MKP

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Well, I'll keep my eyes open for Super-Lube, it may be at my local Ace store, according to there "Where to find" page. I'd prefer not paying shipping.

At my local auto parts place they sell tubes of synthetic brake grease, I forget the exact name, that have caught my attention. Would that work well, or should something more specific to o-rings?
 

MarkM

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At my local auto parts place they sell tubes of synthetic brake grease, I forget the exact name, that have caught my attention. Would that work well, or should something more specific to o-rings?
Depends....things to look for/watch out for
1) you want it to be able to take ~425 deg F
2) make sure it's NOT a dialectric grease as these may be difficult to clean after firing
3) be sure it's not an anti-seize grease since most of these contain metals or other metal-containing grease. The metals will conduct heat, raising the temperature and perhaps cause case burn-through
 

Handeman

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Exactly why I would not use vaseline. It is an inferior product for the application we are discussing. It's not engineered for high temp applications-- loses it's stiffnesss/viscosity even at high ambient temperatures. This can result in it going where it's not supposed to be, etc.

... snip....

I'd be curious how well vaseline actually works and what the ratio of motor failures occur when comparing types of lubricant that were used. Not sure that there's much statistical data out there though..

Again, saving a few nickels using an inferior lubricant in a rocket motor seems the poster child for penny-wise and dollar foolish.
I disagree. I think you are assuming the grease on the o-rings have some purpose and function during motor burn. I believe that is incorrect. From what I understand from the manufacturers instructions, the purpose of the grease is to preserve the integrity of the the o-rings during assembly of the motor. Once it is assembled, the grease has no function. The thermal properties of the grease are irrelevant.

I would also be interested in the ratio of failures for various kinds of lubricants, but I never heard of any failures that were ever attributed to the lubricant. It would be hard to filter out all the assembly errors, faulty parts, and other causes.

What I'm curious about is how much harder or easier it is to clean cases after using different lubes on the liner/not lubing the liner. Is it better to lube the liner or not? Does the heat cause the lube to glue the liner to the casing? Would it be better to not lube the casing so nothing is there to cause adhesion? I always use vaseline, only on the o-ring and threads. in my Hobbyline cases which I fly a lot. I've never had a liner that stuck to the casing and almost never have anything stick to the casing that a baby wipe won't take care of.
 

Diosces

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I disagree. I think you are assuming the grease on the o-rings have some purpose and function during motor burn. I believe that is incorrect. From what I understand from the manufacturers instructions, the purpose of the grease is to preserve the integrity of the the o-rings during assembly of the motor. Once it is assembled, the grease has no function. The thermal properties of the grease are irrelevant.

I would also be interested in the ratio of failures for various kinds of lubricants, but I never heard of any failures that were ever attributed to the lubricant. It would be hard to filter out all the assembly errors, faulty parts, and other causes.

snip
Hande, all due respect but your logic is flawed and you mistakenly assumed something I wasn't assuming.:p

Three years of service repairing/maintaining missile launcher and Tank Hydraulic systems-- I've a bit of experience regarding O rings and their lubricant needs.

Actually, once assembled the function of lubricant continues to have two VERY important factors in a motor.
1) keeps the O'ring lubricated and elastic so it doesn't bind under pressure fluctuations. That way it continues to provide a seal.
2) Lubricant should stay where it's meant and not go into errant places like delay grains etc.

I've read as well as been informed by knowledgeable people that lubricant on a delay grain or in the delay spacer void will cause motor ejection failure...hmm runny, melted vaseline--not good

I will check with the VERY knowledgeable MDRA members at Red Glare VI regarding CATO's and mis use/mis application of lubricants..I'm betting that either have played a critical role in a number of motor failures.

I did some research and compared the physical properties/specifications of hi temp lubricants vs vaseline. I'll continue to use the right material for the job.

And if I happen to misplaced or exhaust mine at a launch I'll ask one of the 40 or 50 friendly people who use the right lubricant for a dab.
 

Handeman

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Hande, all due respect but your logic is flawed and you mistakenly assumed something I wasn't assuming.:p

Three years of service repairing/maintaining missile launcher and Tank Hydraulic systems-- I've a bit of experience regarding O rings and their lubricant needs.

Actually, once assembled the function of lubricant continues to have two VERY important factors in a motor.
1) keeps the O'ring lubricated and elastic so it doesn't bind under pressure fluctuations. That way it continues to provide a seal.
2) Lubricant should stay where it's meant and not go into errant places like delay grains etc.

I've read as well as been informed by knowledgeable people that lubricant on a delay grain or in the delay spacer void will cause motor ejection failure...hmm runny, melted vaseline--not good

I will check with the VERY knowledgeable MDRA members at Red Glare VI regarding CATO's and mis use/mis application of lubricants..I'm betting that either have played a critical role in a number of motor failures.

I did some research and compared the physical properties/specifications of hi temp lubricants vs vaseline. I'll continue to use the right material for the job.

And if I happen to misplaced or exhaust mine at a launch I'll ask one of the 40 or 50 friendly people who use the right lubricant for a dab.
I appreciate the experience and technical knowledge you have. I have also had a lot of experience with o-rings and seals in various systems. I completely agree about the lubrication and use of o-rings in hydraulic/pneumatic systems. It is very critical that the correct materials and lubes be used and in the correct amounts.

I still must disagree with your position on lubricants in solid rocket motors. I think you are applying the wrong engineering to the use of o-rings in solid rocket motors and how they work in a rocket motor, which is very different then in a hydraulic/pnuematic system and any other place where an o-ring has to provide a seal against moving parts. I don't think your point #1 applies to o-rings in a solid rocket motor. There is no way for an o-ring to "bind" in a motor because nothing is moving. If the o-ring has an issue with pressure flucuations in the motor, it is an issue with the o-ring material, not the lubricant. In the rocket motor, the lubricant has to allow the o-ring to move against the different surfaces while the closures are being tightened. Once that is complete, only the elasticity and material properties of the o-ring material comes into play. The surfaces that the o-ring seals against do not move, and thus do not need lubrication to maintain a seal, only proper material selection when it comes to the o-ring properties will provide this. High temp o-ring materials and their properties are much more important then the lubricant.

As for your point number 2, I agree that the lubricant should stay where it is meant to be, but if there is enough lubricant to migrate, then there was way too much used to begin with. This is an operator issue, not a lubricant issue. If a little is good, more is not always better. With the o-ring on the forward end of the delay grain, the lubricant is only there to allow the o-ring to slide into the delay cavity in the forward closure. Any lubricant near the aft end of the delay grain should burn away before it can migrate.

It's the o-rings themselves that seal, the lubricant only protects them during assembly and does NOT affect the seal properties while the motor burns because there is not movement to lubricate for. It's all about the o-rings.
 

Diosces

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I appreciate the experience and technical knowledge you have. I have also had a lot of experience with o-rings and seals in various systems. I completely agree about the lubrication and use of o-rings in hydraulic/pneumatic systems. It is very critical that the correct materials and lubes be used and in the correct amounts.

I still must disagree with your position on lubricants in solid rocket motors. I think you are applying the wrong engineering to the use of o-rings in solid rocket motors and how they work in a rocket motor, which is very different then in a hydraulic/pnuematic system and any other place where an o-ring has to provide a seal against moving parts.
I think you are applying the wrong assumption in thinking it's a SOLID system. :p O-Rings have little or no place in solid only system. A rocket motor becomes a FLUID system once the rocket is ignited, a pressurized fluid system. In many ways similar to a pneumatics system, but with appreciably differences.

Regarding moving parts, there are plenty of 'o' rings in fluid systems that are not located at moving parts, these o rings are will move (thousanths of an inch) and mold to mating surfaces under pressurization differentials.

Handeman, I'm a bit miffed that you keep assuming I'm wrong or projecting that I'm making flawed assumptions. Thats usuallly my wife's job--I've been known to be very wrong ;) I do hope I see you at Red Glare IV or LDRS, we could drag race our Thugs :) or even something larger on a K or L.

I'm mildly surprised that there are several in this thread that champion vaseline as suitable replacement for an engineered highly superior lubricant that costs slightly more money. Especially in the volatile, fault susceptible rocket motor.

My vested interest in this thread is not to be right or wrong but rather I really feel newcomers and readers seeking solutions are ill-served by the recommendation of vaseline as a rocket motor lubricant.
 
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kjohnson

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I use vaseline becasue that's what Ed LaCroix said I should use. I tend to trust the designer of the motor I'm using.

Now most of my reloads to date have been plugged, E6 loads, but I've used the vaseline on everything up to H's to lubiricate the lining before inserting it in the casing.

YMMV.

kj
 

bobkrech

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Vaseline® Petroleum Jelly is a mixture of mineral oils, paraffin and microcrystalline waxes that, when blended together, create a smooth jelly that has a melting point just above body temperature.

https://www.vaseline.com/Product.aspx?Path=Consumer/OurProducts/PetroleumJelly

The difference between Vaseline® Petroleum Jelly and any other hydrocarbon grease is it's melting point as all greases are blends of mineral oils, paraffin and other waxes or thickeners. Greases with lower melting points have have a higher percentage of oil and a lower percentage of waxes. Depending on application, greases may also have fillers (thickeners like silica), antioxidants, viscosity enhancers and high stress additives, but these additives are in the fractional to 10% range. Grease is used as a lubricant to prevent o-ring damage during assembly. It does not form a pressure seal, however a thin coating of grease can extend the lifetime of an o-ring by preventing oxidation of the rubber. So little grease is required for lubrication that it really doesn't matter what the melting point is as it's not going to flow.

The definitive reference on o-rings is the Parker O-Ring Handbook which can be downloaded free of charge as https://www.parker.com/literature/ORD 5700 Parker_O-Ring_Handbook.pdf It probably has more information about o-rings and o-ring seal design than you want or need to know.

There two generic choices for gas sealing: static seals and dynamic seals. A static seal does not require gas pressure to make a seal because by mechanical gland design pressure is applied by the sealing surfaces and precompress the o-ring without gas pressure, whereas a dynamic seal does not. A good designer will always choose to employ a static design where possible as static seals to not require pressure application to test seal integrity as do dynamic seals.

An example of a bad o-ring design was the first SRB o-ring seal design that caused the Challenger Accident. The gland design was a dynamic design where internal pressure was required to move the o-ring to make the seal and the chosen o-ring material was brittle at low temperatures and fractured upon pressurization, and failed in 600 milliseconds, dooming the flight.

https://science.ksc.nasa.gov/shuttle/missions/51-l/docs/rogers-commission/Chapter-4.txt

https://www.me.utexas.edu/~me179/topics/lessons/case4articles/case4article5.html

https://www.aerospaceweb.org/question/investigations/q0122.shtml

https://www.nytimes.com/1987/02/24/science/shuttle-o-rings-in-4th-firing-test.html

https://www.cesar.wsu.edu/~yonge/CE480/challenger.htm

There's some really good lessons learned about choosing o-ring materials and gland design. The SRB o-ring that failed was one of the most expensive materials that o-rings are made from, but unfortunately it was the wrong material for the job. Additionally the gland design was inadequate and allowed for o-ring movement that would allow gas leakage. The Challenger SRB design flaw was unintentional, and the designers did not skimp on materials, they simply did not have a robust design margin to permit the Shuttle management to launch the Shuttle at launch temperatures that were below the design minimums.

Bob
 
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Handeman

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I think you are applying the wrong assumption in thinking it's a SOLID system. :p O-Rings have little or no place in solid only system. A rocket motor becomes a FLUID system once the rocket is ignited, a pressurized fluid system. In many ways similar to a pneumatics system, but with appreciably differences.

Regarding moving parts, there are plenty of 'o' rings in fluid systems that are not located at moving parts, these o rings are will move (thousanths of an inch) and mold to mating surfaces under pressurization differentials.

Handeman, I'm a bit miffed that you keep assuming I'm wrong or projecting that I'm making flawed assumptions. Thats usuallly my wife's job--I've been known to be very wrong ;) I do hope I see you at Red Glare IV or LDRS, we could drag race our Thugs :) or even something larger on a K or L.

I'm mildly surprised that there are several in this thread that champion vaseline as suitable replacement for an engineered highly superior lubricant that costs slightly more money. Especially in the volatile, fault susceptible rocket motor.

My vested interest in this thread is not to be right or wrong but rather I really feel newcomers and readers seeking solutions are ill-served by the recommendation of vaseline as a rocket motor lubricant.
I'm not assuming you are wrong, I just disagree with your assumptions. I could be wrong with my assumptions. I'm also not saying that some lubricants aren't a lot better then vaseline in most locations that o-rings are used. In fact I would never use vaseline on most o-rings I've ever used. I just feel that when used in rocket motors, that vaseline is an acceptable and viable lubricant and does not contribute to motors failures in any significant way. I think in some ways we look at the lubricant the way a lot of us overbuild our rockets. Granted that motors can fail in so many ways, but most of them are easily attributed to assembly error (including how it was lubed), grain voids, or part failures. I've just never heard of a case where the lubricant was the cause of a failure.

I suspect on this subject we might have to agree to disagree. But it sure was interesting discussing it with you. Thanks...

I'm planning on being at LDRS (slot 18) and I would love to drag the Thugs! Any patricular motor class or is it "run what ya brung"? I've got my Rocketry 201 I just flew on a K and J for my L2 cert. That might make a good drag too. Maybe we can get together one night in NY and talk motor lubricants over a couple of adult lubricants!
 

ben_ullman

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Ok. I will make 3 x 3 grain J motors. One I lube the rings with Dow 111, one with vaseline, and One I do not. I will fly them then take pictures. I will do this at Red Glare for all of you to see.

My hypothesis is the grease will do nothing but allow me to reuse the Orings on the bulkhead(the nozzles are 80% shot due to more heat). The one I do not grease probably will have a little more heat on the Orings since the grease is not there to take the heat for the 2.5 sec burn.

Ben
 
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Handeman

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Ok. I will make 3 x 3 grain J motors. One I lube the rings with Dow 111, one with vaseline, and One I do not. I will fly them then take pictures. I will do this at Red Glare for all of you to see.

My hypothesis is the grease will do nothing but allow me to reuse the Orings on the bulkhead(the nozzles are 80% shot due to more heat). The one I do not grease probably will have a little more heat on the Orings since the grease is not there to take the heat for the 2.5 sec burn.

Ben
Ben, I don't think you will see any difference between the two using lubricant. The one without, may have some type of o-ring damage because of the lack of lubricant during assembly and cato during burn. If you're lucky, all three should work the same and all the o-rings should be in about the same condition when done. I do not expect the lubricant will make any difference in the final condition of the o-rings providing they don't fail due to assembly damage.
 

ben_ullman

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My bulkheads aren't to hard to put in since the bottom edge of all my cases is chamfered so they slide in easier. I also rotate as I push my bulkheads in instead of just straigh pushing it in.

Ben
 

Handeman

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I use vaseline becasue that's what Ed LaCroix said I should use. I tend to trust the designer of the motor I'm using.

Now most of my reloads to date have been plugged, E6 loads, but I've used the vaseline on everything up to H's to lubiricate the lining before inserting it in the casing.

YMMV.

kj
I have not been lubricating the casings when putting them in. With paper liners in the hobbyline cases, I've never lubed a liner. I also never lube the liner on the HP loads. I flew two load this weekend. A K695 that had the superlube on the threads of the case, but vaseline on the o-rings. Nothing on the liner. After the flight, I took the aft ring off and the nozzle, liner, seal disk, and delay charge slid out of the casing in one piece. There was almost nothing to clean. I flew a J420R in a 38/720 case. Same thing, superlube on the threads and vaseline on the o-rings, with nothing on the liner. This time the liner cracked the full length. The whole thing slid out of the case and a few swipes with the baby wipes and the casing was clean.

I keep hearing about how hard it is to clean cases, but I'm beginning to wonder if the lubricant on the liner is burning/oxidizing or some how causing the problems with the casings picking up all the hard to clean debris. I've only flown a dozen or so HPR loads, H to K but mostly I loads. I've never lubed the liners and I've never had one that was hard to get out or left hard to clean debris in the casing. Maybe the problems aren't all that common, I'm 0 for 12 on HPR and probably 0 for 50 on the hobbyline loads.
 

ben_ullman

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I agree handeman. I never grease any liners and I have flown a 76-8000 case and slid the liner out in one piece. put the motor brush through it a couple times and it was shiny clean!!

Ben
 

troj

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I keep hearing about how hard it is to clean cases, but I'm beginning to wonder if the lubricant on the liner is burning/oxidizing or some how causing the problems with the casings picking up all the hard to clean debris. I've only flown a dozen or so HPR loads, H to K but mostly I loads. I've never lubed the liners and I've never had one that was hard to get out or left hard to clean debris in the casing. Maybe the problems aren't all that common, I'm 0 for 12 on HPR and probably 0 for 50 on the hobbyline loads.
FWIW, a few years back, AMW started recommending folks not grease the liners, as it's not necessary and it does ease the cleanup process. I believe AeroTech still recommends greasing them.

-Kevin
 

Diosces

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I'm not assuming you are wrong, I just disagree with your assumptions. I could be wrong with my assumptions. I'm also not saying that some lubricants aren't a lot better then vaseline in most locations that o-rings are used. In fact I would never use vaseline on most o-rings I've ever used. I just feel that when used in rocket motors, that vaseline is an acceptable and viable lubricant and does not contribute to motors failures in any significant way. I think in some ways we look at the lubricant the way a lot of us overbuild our rockets. Granted that motors can fail in so many ways, but most of them are easily attributed to assembly error (including how it was lubed), grain voids, or part failures. I've just never heard of a case where the lubricant was the cause of a failure.

I suspect on this subject we might have to agree to disagree. But it sure was interesting discussing it with you. Thanks...

I'm planning on being at LDRS (slot 18) and I would love to drag the Thugs! Any patricular motor class or is it "run what ya brung"? I've got my Rocketry 201 I just flew on a K and J for my L2 cert. That might make a good drag too. Maybe we can get together one night in NY and talk motor lubricants over a couple of adult lubricants!
I agree that we'll continue to disagree on this matter. :) I do respect what your about. For me a lot of my past non-rocket type projects and purchases I always had a tendency or need to jury rig or substitute in some way, usually compromising quality.
With rocketry I find I go out and buy the 'right' or 'best' or 'correctly engineered' product, tool or other for the job at hand.
My last word on this discussion is why settle or suggest a lubricant that has a tendency to turn to a messy liquid on a hot summer day when more suitable lube is readily available at reasonable cost.

Grats on your level 2! i like that you went with a K on the first attempt. I will definitely be at Red Glare 6 flying my growing fleet Any chance you be there? Trying to convince my wife on the wonderfull family activities at NY Finger lakes during the first week in July and that a one day fly by at LDRS would be in order.

At some point we'll meet and I would love to pit my Level 2 bird, carbon fiber Jaguar against your formidable Rocketry 201. Renamed Highway Star she'll fit up to the largest 54 mm so you chose the motor. Currently building a 4" custom fiberglass rocket that will fit 75 mm motors :eek: O my Thug (which you rightly recommended as my first high power rocket) has been modified to fly big J's

Ben, thanks for the consideration regarding the testing. I'd just rather watch you burn loads of AP at Red Glare 6 with motors loaded the way you normally do them.

Dopey polack with a nice rocket1.jpg
 
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ben_ullman

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Ben, thanks for the consideration regarding the testing. I'd just rather watch you burn loads of AP at Red Glare 6 with motors loaded the way you normally do them.
Well you will get to see:
76-8000 Super Polish Rojo N3380
114-9000 Fast Green N2775
98-10000 M2100 Wicked White
98-10000 N3300 Fast Green
76-4800 M1900 Orion (mach rocket motor)
54-2550 L1270 Wicked White (dad mach rocket)
76-6000 M1925 Wicked White
38-480 I328 Wicked White (x 4 in my 1/2 scale Patriot with the M1925 above)

Should be a great launch!!! Flying the most amount of motors and rockets we can!!!

Ben
 

Mike Di Venti

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It basically comes down to products that are made for the job at hand and products that are made for other purposes that will work. Most rocket builders are GREAT at using products other than what they are made for. Personally, I am going to find some of the Slick 50. If I get in a pinch and need something quick, I am glad to know I CAN use vasoline with good success. Never know when you may forget to get out to buy more grease.
Try Amazon.com
They have it in 5packs(tubes) for 24.99 or single tubes for about 6bucks.
That's where I got mine. I used it for the first time in an AMW 75/7600 motor yesterday. The liner slide out with a good push from the forward bulkhead end.
I'm happy with it. I was having problems using the superlube on the amw stuff. the liners were geting stuck and had to be beaten or picked out.
 

kramer714

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Not being smart enough to stay out of this one....

Sounds like there are a few different problem here that everyone is trying to solve with one answer.

Problem 1) O-ring lube - goal lubricate the o-ring, don't mess anything else up.

Almost any of the lubricants mentioned here will lubricate the o-ring, at the risk of being flamed out of existence, the requirements for the o-rings on rockets isn't very severe, the pressures are not that high (in o-ring terms) and the installation is pretty benign. As a bunch of people said, the o-ring lubricaition isn't to help it seal but help it slip into place, a dirty case or cut ring wont provide a good seal with or without grease. The main problem people seem to have is getting grease on the delay. I'm swearing off Vaseline because it does transfer, plus I cant get tape to stick worth a darn after I use Vaseline.

Problem 2) Sticking threads - Goal- finger tight on, same fingers used to remove it. Easy to clean.

I don't know about you but the threads take most of the time cleaning. the gunk in there never really seems to go away, chasing a thread with a toothpick gets kind of boring after a while. I have used a product called Breakfree CLP from a gun store, less gunk good results, again I think this is a case where less is more. I'm wondering if it acts like mold release (see Problem 3).

Problem 3) Sticking liners. Goal- have the liner slide out after launching even when we (never happens right?) forget to clean them after a launch.

I have been greasing those suckers up, 29mm and 38mm, with cases that have been used for 40 plus launches. I think that greasing up the liner is, wait for it, a mistake. Im planing to do an experiment on my cases in the future, yes I will take a hit for the team. At work we use high temperature mold releases to protect anodized aluminum tools from oxidization from epoxy curing agents and to keep parts from sticking. The 'good stuff' actually bonds onto the tool, don't think wax but think a bonded layer. I'm planning to use a product called Freekote 44 https://tds.us.henkel.com//NA/UT/HNAUTTDS.nsf/web/058AA7D048724E028525715C001BD5A6/$File/FREK44-NC-EN.pdf that is good to temperatures well above 400 F, it is actually advertised to 400C!! but I haven't ever used it that high. It should prevent the liners from sticking, be good for MANY launches, and doesn't transfer.
 

daveyfire

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thank u, next
This is almost as good as a Kevlar vs. Nylon debate :D

Anecdote:
I was a very nervous, sweaty teenager on the morning of my L3 flight. I didn't have any grease. So I wiped my forehead with my fingers, rubbed them on the o-rings of the motor, and assembled it. No problems.

I rarely lube liners. They seem to come out easier with no grease. I'm betting that it's because there's no grease to "seal" the liner to the case after the burn. Before the burn, it's easy to slide the liner in with the cold grease, as it's somewhat unevenly applied. When the motor burns, the grease softens (or liquefies in the case of Vaseline), and can move around. The result usually seems to be an evenly distributed film of grease. After the motor cools down, when trying to pull the liner out, it seems to get "vacuum sealed" to the motor casing, and becomes significantly more difficult to remove.

Over the past ten years, I've used SuperLube, Vaseline, White Lithium, Dow 111, the aforemetioned forehead grease, Krytox in hybrids, and saliva to lubricate motors while loading. Though important, the seals in a hobby rocket motor don't seem to undergo much movement -- I wouldn't count the few thou of squeeze-out during pressure loading as significant -- and I've never had a failure during a burn.

YMMV, IANAL, etc. etc. Do what makes you happy!
 

Diosces

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Not being smart enough to stay out of this one....
Lol, some forum thread have "Danger Keep out!" written all over them written and we still stick our noses in ;)

Sounds like there are a few different problem here that everyone is trying to solve with one answer.

Problem 1) O-ring lube - goal lubricate the o-ring, don't mess anything else up.

Almost any of the lubricants mentioned here will lubricate the o-ring, at the risk of being flamed out of existence, the requirements for the o-rings on rockets isn't very severe, the pressures are not that high (in o-ring terms) and the installation is pretty benign. As a bunch of people said, the o-ring lubricaition isn't to help it seal but help it slip into place, a dirty case or cut ring wont provide a good seal with or without grease. The main problem people seem to have is getting grease on the delay. I'm swearing off Vaseline because it does transfer, plus I cant get tape to stick worth a darn after I use Vaseline.

Problem 2) Sticking threads - Goal- finger tight on, same fingers used to remove it. Easy to clean.

I don't know about you but the threads take most of the time cleaning. the gunk in there never really seems to go away, chasing a thread with a toothpick gets kind of boring after a while. I have used a product called Breakfree CLP from a gun store, less gunk good results, again I think this is a case where less is more. I'm wondering if it acts like mold release (see Problem 3).

Problem 3) Sticking liners. Goal- have the liner slide out after launching even when we (never happens right?) forget to clean them after a launch.

I have been greasing those suckers up, 29mm and 38mm, with cases that have been used for 40 plus launches. I think that greasing up the liner is, wait for it, a mistake. Im planing to do an experiment on my cases in the future, yes I will take a hit for the team. At work we use high temperature mold releases to protect anodized aluminum tools from oxidization from epoxy curing agents and to keep parts from sticking. The 'good stuff' actually bonds onto the tool, don't think wax but think a bonded layer. I'm planning to use a product called Freekote 44 https://tds.us.henkel.com//NA/UT/HNAUTTDS.nsf/web/058AA7D048724E028525715C001BD5A6/$File/FREK44-NC-EN.pdf that is good to temperatures well above 400 F, it is actually advertised to 400C!! but I haven't ever used it that high. It should prevent the liners from sticking, be good for MANY launches, and doesn't transfer.
Actually I think you did an EXCELLENT job summarizing the pros and cons and faults and solutions regarding motor lube. Well done!

For cleaning threads--a stiff nylon toothbrush dipped in your solvent of choice should help.
 

Handeman

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That's a valid suggestion Ben, but since I don't fly research, using snap ring cases would severely limit my choice of loads when you consider the assortment the vendors in my area carry.
 

Mikus

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I'd imagine vaseline will do more harm than good to the O rings.
Not to mention (oopsy, I guess I did) it melts in the Texas heat. Nothing like finding a big ole slick in your range box.... :eek:
 

Handeman

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Not to mention (oopsy, I guess I did) it melts in the Texas heat. Nothing like finding a big ole slick in your range box.... :eek:
The vaseline doesn't damage o-rings, but melts in the Virginia sun too. I bought my in a squeeze tube. It never leaks, but you do have to be careful when opening the snap top on a hot day.
 

ben_ullman

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That's a valid suggestion Ben, but since I don't fly research, using snap ring cases would severely limit my choice of loads when you consider the assortment the vendors in my area carry.
VERY soon that won't matter. You can get any load from anywhere with haz and get it shipped. PLUS Performance Hobbies Carries Loki, AMW, CTI, and aerotech.

Ben
 
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