hindsight Posted February 7, 2014 Share Posted February 7, 2014 What beneficial effect is obtained by coating the inside of paper tubes with wax or other compound? Link to comment Share on other sites More sharing options...
schroedinger Posted February 7, 2014 Share Posted February 7, 2014 Waterglass will strengthen the tube, and help with burn through problems. Woodhardner is used to harden paper tubes, so they get a higher wall strenght Link to comment Share on other sites More sharing options...
hindsight Posted February 7, 2014 Author Share Posted February 7, 2014 Hallo schroedinger-- Wax, however, would (if anything) weaken the paper tube, no? Link to comment Share on other sites More sharing options...
schroedinger Posted February 7, 2014 Share Posted February 7, 2014 Sry never heard about wax coating, and how it would behave. But if the wax coating is done proper, i could imagine that it won't weaken the tube very much, if even at all. But a wax coating at the outside could be used to make the tube waterproof. This could be interesting for storing sugar based engine or other things witch contain hygroscopic substances. Link to comment Share on other sites More sharing options...
Col Posted February 7, 2014 Share Posted February 7, 2014 Waxing the tube alledgedly allows hotter fuel to be used which would otherwise result in a cato. Most of the waxed bp motors seem to be pressed to whistle pressures (9k psi) which will affect the outcome more than the wax coating. Link to comment Share on other sites More sharing options...
Nessalco Posted February 7, 2014 Share Posted February 7, 2014 Head on over to fireworking. All the related info is there. KO Link to comment Share on other sites More sharing options...
Mumbles Posted February 7, 2014 Share Posted February 7, 2014 I'm actually pretty interested myself. Would anyone mind giving us the gist of the effect? About the only nugget I've heard is that people tend to think that it helps the BP adhere to the wall better to help prevent CATOs in red-line rockets. Is this still the general consensus? Link to comment Share on other sites More sharing options...
Nessalco Posted February 7, 2014 Share Posted February 7, 2014 (edited) First off, I'm not a pyro rocket guy. Coming from HP rocketry, I'm able to follow what those guys are doing. The wax seems to have two effects. First is to lubricate the pressing process, eliminating wrinkling and compression of the tube under press loading (8K+ psi). The thinking is that this eliminates cracks in the propellant from rebound effect that occurs when the motors rest after pressing. This minimizes runaway burns and the resulting CATOs. Second is to inhibit the grain from burning up the outside of the grain, along the inner wall of the case. This limits the total burn area, and moderates the burn rate to something that will hold together using hot BP fuels. Dave Forster discovered and promoted this method. There are guys pressing 1# motors with peak thrusts of over 60, approaching 70 pounds. Works well to get a heading aloft. Kevin Edited February 7, 2014 by Nessalco Link to comment Share on other sites More sharing options...
hindsight Posted February 7, 2014 Author Share Posted February 7, 2014 Kevin-- Thanks for the explanation. The lubrication effect -- i.e., the prevention of wrinkling and delayed re-expansion --makes sense, especially when pressing at high pressures. Would using a silicone spray achieve the same effect, or is the presence of a "sheerable", thicker wax layer necessary? The second effect of an inhibited outer grain burn is beyond me, although your explanation is excellent. Is this burn geometry demonstrable practically ,or just a theory? Clearly, higher thrust with the same motor is attractive, but before getting involved with methods of hot waxing my NEPT's, it would nice to know if a simple thin coat of silicone would accomplish the same end. Link to comment Share on other sites More sharing options...
hindsight Posted February 7, 2014 Author Share Posted February 7, 2014 Col, If I understand you, pressing at higher pressures would overshadow the benefits of waxing. Link to comment Share on other sites More sharing options...
Maserface Posted February 7, 2014 Share Posted February 7, 2014 I wouldnt usually say this, but there is like 500 pages about this on fireworking. Needless to say, I wax all of my tubes. Link to comment Share on other sites More sharing options...
ddewees Posted February 8, 2014 Share Posted February 8, 2014 I'll have to try this... I get the "wrinkled tube" look all the time... but I haven't seen any negative effects from it though. Link to comment Share on other sites More sharing options...
hindsight Posted February 8, 2014 Author Share Posted February 8, 2014 Kevin and Maserface,Thanks for the direction. Just finished speed-reading the extensive Fireworking threads on waxing tubes (eyeballs are bleeding). Kevin, you have done an amazing job of summarizing, in a couple of sentences, much of the theory discussed there. Apparently, just a coat of lubricant would not provide the same performance as coating the tube with wax does by allowing the use of hotter fuels without CATO. On Ned's site, there are more methods of waxing tubes described than one might care to read. Yet one more variable to complicate the process of rocket-making! --hindsight Link to comment Share on other sites More sharing options...
ddewees Posted February 8, 2014 Share Posted February 8, 2014 What's the easiest way to line the tube? Press a plug into the bottom, then flip it over and press on through? Link to comment Share on other sites More sharing options...
nater Posted February 8, 2014 Share Posted February 8, 2014 Join fireworking and find out. Link to comment Share on other sites More sharing options...
ddewees Posted February 8, 2014 Share Posted February 8, 2014 Thanks... I guess. 1 Link to comment Share on other sites More sharing options...
pyrokid Posted February 8, 2014 Share Posted February 8, 2014 What's that supposed to mean? Please let the secret out for those of us who don't always like to pay to play. Link to comment Share on other sites More sharing options...
nater Posted February 8, 2014 Share Posted February 8, 2014 That is exaxtly it. Dave chose to share his method on Ned's site. It would be his choice to share it anywhere else. Out of respect for Ned and Dave, I will not share it. 1 Link to comment Share on other sites More sharing options...
leedrill Posted February 8, 2014 Share Posted February 8, 2014 exactly nater after hearing about a technique it is easy to make quitew a good evaluation as to the reason for doing it i dont feel the real reason for the forster method has even been brushed on in this thread and will also maintain secrecy out of respect but those that have pressed bp motors to high pressures with straight meal and meal with oil ect ect as use to be the standard but the forster method offers many advantages and joining fireworking will definitely show you all the pros and cons the only con realy being that the lubrication allows for the grain to relax easier wich was addressed by steve la pioneer duke but dave forster is a very very great asset to our motor making hobby i am excited too see what he comes up with next he is from what i can see a guy trying new things not just changing methods he seems to try to reinvent the wheel wich i was taught not to do but it seems you really can improve on the wheel still even in this day and age Link to comment Share on other sites More sharing options...
Nessalco Posted February 8, 2014 Share Posted February 8, 2014 I'd also mention that the discussion on Fireworking is ongoing, new info is coming in all the time, and there's a lot of other outstanding discussion about pyro - and a very civil atmosphere. $40 is a bargain. Mind you, I still like APC, a lot, but the info on FW is really growing by leaps and bounds. i dont feel the real reason for the forster method has even been brushed on in this thread Agreed. It is discussed on FW. Kevin Link to comment Share on other sites More sharing options...
jessoman Posted February 8, 2014 Share Posted February 8, 2014 (edited) +1 from me too I also wax my NEPTs BIG difference in pressing. Rocketry in fireworking and combined with this site will make anything possible. Couldn't agree more with what everyone's saying. Edited February 8, 2014 by jessoman Link to comment Share on other sites More sharing options...
ddewees Posted February 8, 2014 Share Posted February 8, 2014 Fair enough. I'll join just to see what all the hullabaloo is about. My brain can't imaging how wax inside a tube can make such a significant difference... I'm very curious. Link to comment Share on other sites More sharing options...
Peret Posted February 8, 2014 Share Posted February 8, 2014 In the beginning, it was to do with CATOs. High ramming pressures forced the powder into the surface of the paper tube and compressed it lengthways, then as it relaxed like a spring afterward it put the pressed powder into tension and cracked it, resulting in CATOs. The wax cured that, and then other advantages appeared. On Fireworking dot com they're calling it the biggest advance in amateur rockets since the invention of the stick. Link to comment Share on other sites More sharing options...
mikeee Posted February 9, 2014 Share Posted February 9, 2014 Everyone knows when you wax a surface the air flows over it more smoothly and increases the speed. Waxing provides several advantages when pressing rocket motors. Not much wax is needed for the purpose.It will be the standard in the hobby after everyone figures out what advantages it provides. Link to comment Share on other sites More sharing options...
VikingPyrotechnics Posted February 9, 2014 Share Posted February 9, 2014 (edited) I tried it and I am impressed. I'll wax all my tubes in the future. here a picture of my waxed tubes. http://img5.fotos-hochladen.net/uploads/img2014012321o1zr63l7nh.jpg Edited February 9, 2014 by VikingPyrotechnics Link to comment Share on other sites More sharing options...
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