about on r.m.r. for a year or so. We've got a lousy newsreader here an I've never bothered to figure it out & don't even know if it will post properly. I respond via email when I see something to comment on. Anyway I saw a mention of the CIS RELOAD.TXT file (tho I didn't see the original poster). I don't have an FTP ability at the moment or I would have uploaded it myself, but if you want to put it up, I'll enclose it here. I originally edited & posted this file to CIS with notification of the individual authors of the thread. There is plenty of rmr stuff cross-posted to the Modelnet library so I can imagine there would be any gripe to its being placed in the archive. As a matter of fact, I am the semi-offical librarian on Modelnet, and I have a half-dozen or so programs and files that I intend to upload as soon as my FTP comes back. I'll let you know when that happens. GC RELOAD.TXT follows: S8/Sport Rocketry 22-Aug-94 Sb: #241013-#LDRS Comment [RMS Assembly - 'O' Ring Grease] Fm: Marc McCauley 70157,556 >>The "Texas" rocket that augered in about 50 yards from the porta-potties and 100 yards from the range tent at this year's LDRS certainly qualifies as a close call in my book.<< FWIW, ejection failure was due to TOO MUCH GREASE. The hole at the bottom of the ejection charge well was clogged. I happened to be at the range head when Bill came out to see Rosenfield about the failure of his K550. Gary diagnosed the problem quickly and correctly :-) Pay attention here, folks! This could happen to you.... Fm: Bob Littlefield 73163,113 How many times do I have to say this?? You really don't need any more grease on the o-rings than just enough to make them a little shiny. Take a small amount of grease and rub it between your fingers, just enough to make them shiny. Then barely coat the o-ring just enough to make it shiny. Any extra should be removed. You should not be able to see any extra grease. Clean your fingers by wiping them on the threads of the aft and fore closure. You do *not* need more than a light coating here either. (Light, as in a film coating). Next month, I'll have my 100'th flight on my RMS set and I think I'll probably get another 100 out of it. The little bity tube that you get with the set is more than enough for 100 flights. Just be very liberal with it and you should not have any ejection problems. Fm: Doug Pratt, Chief Sysop 76703,3041 I solved the problem completely for myself by getting a spray can of Super Lube from the hardware store. Lay out the O rings on the plastic bag and give them a quick shot of Super Lube. That's all they need. The aerosol also makes it super-simple to grease the inside of the casing! Fm: JOHN H. CATO, JR. 73551,1730 As a matter of record, we had some of these same 'ejection failures' at TMT - getting a little too carried away with the grease. Basically, when the motor comes up to pressure, it extrudes any excess grease around the delay column out onto the top - effectively 'snuffing out' the ejection charge. Moral: use just enough up front and not a bit more. Fm: Stuart Barrett 75013,1051 John, I'm a little confused. If the o-rings are positioned correctly they should block any excess grease around the delay column from getting around to "snuff" out the ejection charge. I usually grease the inside wall of the forward closure, and the inside wall of the delay insulator so if this scenario was true I would think that I would have "experienced" it. Fm: Marc McCauley 70157,556 I can't speak to the 'extrusion' point other than to say, when the motor comes up to pressure the gas is going to seek any and every outlet. Like you, I would think that improperly seated delay o-rings would be the culprit. However, if you have allowed the chamber gasses to begin escaping around the delay column, I would think early ejection due to burn-by would be the more likely result. Let's talk about where we put the grease. No doubt you have seen excess grease being pushed forward at the leading edge of whatever is being inserted. i.e., if you lube the inner wall of the forward closure, a snugly fitting delay insulator will 'push' the excess forward. OTOH, if you lube the outside of the insulator, the excess is left behind on the rear lip of the closure. There is obviously a fine line here, since the grease serves the dual function of seal and lubricator. My 'feeling' has always been that the sealing function occurs at the 'micro' level...closing off minute gaps only...since the chamber gasses would certainly bypass any large gaps at pressure. The physical pressure of assembly should compress the o-rings and do the majority of the work in this regard. The lubing occurs mainly on the fore and aft closures and threads. This prevents the large rings from being torn or distorted when the closures are cranked down. The main thing here, as YOU know, is to keep the propellant and delay surfaces free of 'contaminants' that would inhibit or prevent ignition. I think it's safe to say that ejection problems with reloads are almost always due to improper assembly. Over-pressurization failures(catos) are another animal altogether. Fm: JOHN H. CATO, JR. 73551,1730 Stu, It all depends on what pressure we're talking about. If you get enough pressure, and have enough excess material, it is doubtful that an O-ring will be an effective 'dam'. It also was not known if the O-rings, themselves, were not excessively covered - under that scenario, they would serve no 'blocking' function - the grease is already past them. (Remember, also, that little fiber washer that sits inside the 0-rings. With it's much higher hardness, it will, in effect, stop the continued compression of the O-rings - at least to some degree. Gary would be the better one to comment on some of this - with their much broader experience). Fm: Gary Rosenfield 73624,224 >>If the o-rings are positioned correctly they should block any excess grease around the delay column from getting around to "snuff" out the ejection charge.<< That's true, but it doesn't stop the grease on the ejection charge side of the o-rings. When the motor is under pressure, the o-rings compress further, and excess grease on the o-rings *could* reach the black powder. Fm: Larry D. Smith 71022,3270 Truer words were never spoken! I keep saying the same thing whenever I get a chance. I have flown over a hundred RMS motors and have never had an ejection failure (well, unless you want to count the one where I left the ejection charge out of the motor!!!). Just shiny, you do not want to be able to see the grease on the O-ring. Also, make sure that the delay liner fits tight enough to not slide up once inserted. It only needs to move 1/32" for the O-rings to slide under it and then you are going to get a blow through and early ejection! Fm: Stuart Barrett 75013,1051 One technique that I use is to always make sure that when I screw in the forward closure into the case, both units are horizontal. This keeps the delay column/o-rings from slipping down. The 54mm instructions suggest this technique, I use if on all of my reloads (29, 38). I also add a tape shim to the delay stack and/or insulator if it appears too loose. #: 244511 S8/Sport Rocketry 06-Sep-94 08:55:44 Sb: #244459-54mm Casing Cleaning Fm: Marc McCauley 70157,556 Since we're on the subject, I'm gonna throw out the method I have developed and let the 'public' pick at it. Since I fly reloads at virtually every launch I attend, I find myself answering LOTS of questions from those that are new to reloads. This puts me in the uncomfortable position of 'expert', which I'm not...it's just not 'new' to me anymore. I do make it a point to be present at motor disassembly after a reload failure, as do several others in our club. Not only have I learned a lot, but it gives us the opportunity to determine the failure mode and discuss with the user how to avoid the problem in the future. So here we go.... 1) Read the instructions. (I don't care how many you've done) 2) Make sure all parts are present. Doing (1) will help you visualize their placement. 3) Test fit the parts. Pay special attention to the delay insulator and delay element. If they are loose and must be shimmed with masking tape, use a full wrap. 4) Run a bead of grease the full length of the grain liner. Holding the liner in one hand, work it around until it is coated completely. You will have enough grease left on your hand to do all the other parts. 5) Scrape the ends of the casing across your hand to get a small blob of grease inside on the threads. Use a finger to spread this over the threads and down into the tube about 1" past the threads. 6) Grease the threads on the closures using the same 'scrape and spread' as number (5). 7) Lube the flat surfaces of the closures that face inside the motor and the inside of the delay cavity. We're looking for complete coverage with NO excess. We have reached the point of 'just shiny'. 8) Lube all o-rings by working them around in your palm. Again, shiny with no excess. 9) Lube the outside of the delay insulator and delay element. Complete coverage, shiny, NO excess. 10) Be sure that there is NO grease on the exposed surfaces of the delay element or propellant grains. 11) When inserting the liner/grain assembly into the case, push it all the way out the other sidean inch or two, twist 1/2 turn and re-insert. This is to ensure a complete coating on the inside of the case. Remove any excess grease that gets pushed up around the ends of the liner or on the threads. 12) Assemble the forward closure/delay element. Put the delay insulator in first, then the small o-rings. Using your finger or other tool, seat the o-rings against the forward wall of the closure. BE SURE the small one is inside the larger and that both are FLAT against the closure wall before you insert the delay element. Check carefully to be sure that the hole for the ejection charge is DRY AND CLEAR. Check again to be sure there is no grease on either end of the delay element. 13) Insert the delay element(and spacer). Check to be sure the element or spacer is protruding as illustrated in the instructions. If it is too much, or not enough, disassemble and fix the problem. 14) Be sure that the large o-rings and insulator washers are properly placed and flat(perpindicular to the case) before putting on the end closures. 15) After pouring in 1/2 the ejection powder you plan to use, tap the motor a few times to ensure that the powder goes down inside the forward closure. Pour in the rest of the powder. Use a piece of masking tape on top of the paper dot to hold it in place. I don't trust it to stick by itself after the closure has been handled with greasy hands. If this bothers you, make a 1/8" slit in the tape with an Xacto knife. This is a very general guideline. Since different reloads are not configured the same, it is CRITICAL that you read the instructions EVERY TIME you assemble one. Assembly sequence can be VERY important. Pay careful attention to the notes and warnings. Ask questions if you are not sure of some detail. OK boys and girls, have at it...did I leave out any important details? If you feel ANY of this is wrong, say so...I'm still learning, too. Marc. #: 250208 S8/Sport Rocketry 01-Oct-94 11:27:38 Sb: #250191-Aerotech RMS Tricks? Fm: Doug Pratt, Chief Sysop 76703,3041 To: Rich Emmings 72150,452 (X) Go to ghe grocery store and get a canister of Wet Ones. On your way home, stop by the hardware store and get a small spray can of Super Lube. You can substitute baby wipes for the Wet Ones, but make sure you get genuine Super Lube. Before loading the RMS casing, give it a light spraying on the inside with the Super Lube. SL comes out as a liquid and quickly turns into a gel, giving you enough time to roll it around in there and make sure the entire interior surface gets covered. This will make disassembly and cleaning a LOT easier. Super Lube was designed for bicycle chains, and actually repels dirt. Lay your O-Rings out on a piece of plastic and give them a quick squirt of Super Lube. Not too much! They just need to be shiny. The most time-consuming part of turning around an RMS, in my experience, is cleaning the threads. I do it with my thumbnail through a layer of Wet Wipe. I'm scrupulous with the threads, because I just hate that gritty feeling when I screw the closures on. Fm: Chuck Gibke 72477,2531 To: Doug Pratt, Chief Sysop 76703,3041 (X) RE: RMS tricks Have you found a good way to clean the knurled edges of the closures (mainly the 38mm set). These seem to get grimy down inside where it is tough to get at 'em, especially the gold/brass end. Fm: Doug Pratt, Chief Sysop 76703,3041 They used to drive me berserk, then I stumbled--literally--over something that takes the crud right off. Spray mag wheel cleaner. I had a box of stuff in the workshop that we had moved from our old house last December, and it was too heavy to move so I opened it up and was throwing stuff out...when I picked up the cleaner, I had some RMS closures on the bench to be cleaned, and thought, "Why not?" Durned if it didn't work like a charm. Watch out for this stuff, though; it's nasty. Don't get it on your skin or in your eyes, and read the instructions on the label! Fm: JOHN H. CATO, JR. 73551,1730 Doug, go to a welding shop and get one of those toothbrush size *brass* (not stainless) brushes. Dip it in a little lacquer thinner and 'grunge under the thumbnail' will be a thing of the past . (You'll also save a lot on Wet Wipes ). Fm: Gary Rosenfield 73624,224 Here are some tips that I posted a while back: 1. Always use grease sparingly. Apply a thin coat of grease to the o-rings. If grease covers the face of the delay element, ejection charge reliability will suffer. Use enough grease on the threads to allow the closures to tighten smoothly. 2. Make sure you shake the completed motor, ejection cap up, before installing in the rocket. This settles some of the ejection charge in the transfer cavity above the delay element, which helps to ignite the charge when the delay burns out. 3. Make sure the end closures are tightened completely against the case. This preloads the o-rings to prevent combustion gas leakage. 4. The delay element or delay spacer must protrude slightly (about .020"-.030") above the forward closure after being installed. When the closure is tightened, the delay or spacer compresses the delay o-rings. 5. Ensure that the motor is cleaned thoroughly after each use. Residues, especially in the forward closure delay o-ring area, can prevent proper sealing and result in the forward closure being turned into a nozzle. 6. Inspect the o-rings for nicks, cuts, thin sections or other defects. AeroTech will replace these or any other defective parts you find in your reload kits. Defective o-rings can cause hot gas leaks and motor failure. Don't use a reload kit with defective or missing parts. 7. The parts must be assembled in the correct order and location. We've seen o-rings stretched around the end closure threads, for example. Needless to say, the subsequent flight using that motor was less than perfect. 8. If you have a misfire and need to remove the aft closure and nozzle insert to install a new igniter, hold the motor nozzle up and avoid moving the liner or other internal parts. If the delay moves after the ejection charge is installed, the charge may leak under the delay o-rings and cause a forward seal failure. 9. Don't leave a motor assembled for an extended period. This can cause a compression set of the delay element. If necessary to store the motor before launch, loosen the aft closure slightly (a couple of turns) to reduce the preloading of the delay o-rings. 10. A real indication of trouble is if you have parts left over. Check your assembly again, or call AeroTech. >>Even though it's a no-tool process, are there any tools that may be useful?<< A hobby knife is useful for clearing out the ejection transfer port in the forward closure. The edge of a 6" steel ruler can be used to (gently) scrape any carbon build-up from the inside ends of the motor case. >>What are the stability issues -- are the RMS casings heavier than the non-RMS casings or to put it another way, if it flies on a single use E, will it fly on a RMS E of similar power, with a bird with a tight CG/CP relationship, or will CG be pulled back towards the engine.<< The RMS casings are a *little* heavier than their single-use counterparts, but no stability problems have yet been discovered or reported. You should always check the stability of a questionable rocket/motor combination before flight. >>Also, what's the expected turn around time from flight to flight. The catalog says 5 min to assemble, but doesn't mention anything about the time it takes to get the old components out.<< If you rush, you can re-load in less time, but it's not recommended . My estimate is 5-10 minutes under typical conditions.