killforfood Posted May 11, 2011 Posted May 11, 2011 I know the Mods discourage "necro-posting" but this was a timely resurrection for my current needs. Lots of good contributions by the usual suspects.
dagabu Posted May 11, 2011 Posted May 11, 2011 Estes sure has a great performance history with their end burner model rocket motors, I've never matched their might without using more propellant, etc.Rcandy core burners are much easier to track and work just fine though.Nice white spiraling plume even in the delay, BP meal is still the only predictable way to eject the chute though. With a good press, good powder and NEPT tubes, its pretty easy to duplicate ESTES motors. The secret was actually in the press and the nozzle, not the fuel. -dag 1
guntoteninfadel Posted May 11, 2011 Posted May 11, 2011 WTF is "necro-posting"? Hell, English is my first language and I dont get that.
dagabu Posted May 11, 2011 Posted May 11, 2011 I know the Mods discourage "necro-posting" but this was a timely resurrection for my current needs. Lots of good contributions by the usual suspects. Necro is Latin for death, it means essentially, bringing a post back from the dead. -dag
Bilbobaker Posted May 11, 2011 Posted May 11, 2011 With a good press, good powder and NEPT tubes, its pretty easy to duplicate ESTES motors. The secret was actually in the press and the nozzle, not the fuel. -dag Most certainly a great tube and nozzle what is their fuel ratio?
dagabu Posted May 12, 2011 Posted May 12, 2011 It is the optimal ratio for BP, the secret was the dwell time on the fuel grain, the machine (Mable I think) pressed the fuel grain slowly over time as the turret indexed and rotated, the fuel grain was pressed so hard that it rang when tapped. Also look at the depth of the nozzle clay, the web is much deeper then what we press. -dag 1
Mumbles Posted May 12, 2011 Posted May 12, 2011 The PFP offers an alleged Estes rocket propellant formula. It's pretty close to 5:1:1 http://www.privatedata.com/byb/pyro/pfp/rocket.html Ned has a disection on this page: http://www.skylighter.com/fireworks/how-to-make/model-rocket-engine.asp
Blackthumb Posted May 12, 2011 Posted May 12, 2011 I just found 120 plus Estes engines in the back of my closet..........have no need for them..... Also...just rec'd some good looking KNO3...only took 3 days USPS....25# ...$60.00
mabuse00 Posted May 12, 2011 Posted May 12, 2011 Seems like they press them wet. Or whats the dextrin for...?
dagabu Posted May 12, 2011 Posted May 12, 2011 Good question, Dextrin is a binder, it makes for a very hard fuel grain. The stories from Vern Estes, the powder was dry when pressed. -dag
Mumbles Posted May 12, 2011 Posted May 12, 2011 For accurate loading by machine, the composition must be granulated. It's probably just in there to make the grains more durable during storage.
Bilbobaker Posted May 12, 2011 Posted May 12, 2011 I like that skylighter dissection link. So they just use standard BP and have one heck of a slow but very powerful press.Wonder why not Rcandy? Probably wouldn't have the needed shelf life I bet.
dagabu Posted May 12, 2011 Posted May 12, 2011 I like that skylighter dissection link. So they just use standard BP and have one heck of a slow but very powerful press.Wonder why not Rcandy? Probably wouldn't have the needed shelf life I bet. Not just a hazardous manufacturing processes but expense, lack of performance (sugar rockets use cores) and inefficient fuel not to mention a hot process needed to handle the melted candy and a cooling process. The product would not be shelf stable and special packaging would be needed. I still have Estes motors from 1976 when I launched my first Mosquito model rocket. They work every bit as well now as they did 35 years ago -dag
Bilbobaker Posted May 13, 2011 Posted May 13, 2011 Not just a hazardous manufacturing processes but expense, lack of performance (sugar rockets use cores) and inefficient fuel not to mention a hot process needed to handle the melted candy and a cooling process. The product would not be shelf stable and special packaging would be needed. I still have Estes motors from 1976 when I launched my first Mosquito model rocket. They work every bit as well now as they did 35 years ago -dagI agree Estes makes excellent rocket motors but they start to add up if you launch enough rockets, building your own rocket engine is pretty fun and educational IMHO.The Rcandy is much less messy than packing ball milled meal powder.It's ok to make a medium batch roll it into 50 gram balls and store them in a ziplock bag with desiccant media to keep them dry and just warm them as needed to mold into motor casings.Recently (actually been a couple years ago now) I too discovered a half dozen Estes A motors and just had to build a tiny little rocket to use them up.All worked like new.
dagabu Posted May 13, 2011 Posted May 13, 2011 I agree Estes makes excellent rocket motors but they start to add up if you launch enough rockets, building your own rocket engine is pretty fun and educational IMHO.The Rcandy is much less messy than packing ball milled meal powder. My experience is just the opposite, I have more clean up after making R-candy then making BP and I can store my BP indefinitely in a paper bag while my R-candy melts if not double bagged and stored in the freezer. Don't get me wrong, I have a love affair with R-candy but it is no replacement for good old BP. -dag
Bilbobaker Posted May 17, 2011 Posted May 17, 2011 kn/sui with 1.5% red iron oxide for end burners.Why red iron oxide and not black? Just curious
dagabu Posted May 17, 2011 Posted May 17, 2011 Why red iron oxide and not black? Just curious Brown, yellow, red and black all work as a catalyst with brown *reportedly out performing the others. *DC -dag P.S. Don, please dont use acronyms that are cryptic or ambiguous. "kn/sui with 1.5% red iron oxide for end burners."
dagabu Posted August 21, 2022 Posted August 21, 2022 I have been doing HP rocketry since the 1980s but I have to say, I have never made en end burner! Sugar, RC-Candy, AP, BP, all core burners. I launched a bunch of 3# two stage rockets at PGI this year and I have one 3#er lift a 5" ball to 300'. It broke well and all the stars went out before landing. It was a prefab shell but it did work. I am having pianomistro make me a set so I can see what all the fuss is about end burners. Dave Talk about a necro-post! 13 years have passed since I wrote the above post and I have shot about 2000 since that time. For those just learning to make rockets, I am using ball-milled BP using the 75:15:10 Sir Francis Bacon formula using Humphry's airfloat charcoal and 2% white dextrin liquor (137.5g of water and 20g of white dex in a 1 kilo batch of BP). I am also pressing them to 6500PSI in small increments in order to control the burn rate and slow the burn some. Most of the motors I make nowadays are being used to power Girandolas so I am using 6-18 motors each launch and I have them dialed in pretty good! Interestingly enough, I am making a bunch of 5/8" ID motors to launch 8" dolas as of late. They scratch the itch but take just a small amount of powder (21g each) to make. 1
nordicwolf Posted September 1, 2022 Posted September 1, 2022 So about the 75:15:10 described just above ... is that what you use in the end-burner set you got 13+ years ago? What is your mix for core burners? Do you add dextrin to that? Does the dextrin reduce risk of CATO? I have 1/2" tooling for end burner and core burner. I have a press, ball mill and ERC charcoal. I am considering 6:3:1 (or just 6:3) for the core burner, and 75:15:10 for end burner. Hopefully the ERC is not too hot for the tooling ... it seems most of the posts I have read suggest commercial hardwood which I understand is slower. I also have 3/4" universal tooling (and something called Econo Tooling for 3.75" x 3/4" tubes, spindle shape looks like universal, fatter than core burn and a bit shorter). Anyway for the Universal and Econo Tooling I am considering 75:15:10 with ball milled ERC. If I were to try the Steve Laduke formula 60:30:10, I would ball mill 60:15:10 to get the fine meal, then add in 15 of 80-Mesh. Except I do not have commercial hardwood charcoal. Oh! one last question...where do you fuse the core burn motors? I have been told that if you use quickmatch to get ignition at the top of the core, the motors take off like a bat out of hell. If you fuse it so the ignition is at the bottom of the nozzle, the power is greatly reduced but still functional. In other words, another way to control thrust is where you fuse the motor. So many variables! Thanks.
nordicwolf Posted September 1, 2022 Posted September 1, 2022 and thanks for posting about Humphrey's charcoal. I may order a 20# bag of the hardwood lump charcoal to try it out as a source for, um, hardwood charcoal. Hopefully shipping is not a killer. I guess I should look locally as well to see what sort of similar charcoal may be available at retail.
dagabu Posted September 1, 2022 Posted September 1, 2022 (edited) So about the 75:15:10 described just above ... is that what you use in the end-burner set you got 13+ years ago? What is your mix for core burners? Do you add dextrin to that? Does the dextrin reduce risk of CATO? My mix is always the same for BP, 75:15:10 plus 2% white dextrin liquor (137.5g of water and 20g of white dex in a 1 kilo batch of BP). I use the same BP for core burners, end burners, zips, girandola drivers, monocopter drivers and Z-bombs. Dextrin MAY reduce the RUDs but I dont see a difference with my rockets. I have 1/2" tooling for end burner and core burner. I have a press, ball mill and ERC charcoal. I am considering 6:3:1 (or just 6:3) for the core burner, and 75:15:10 for end burner. Hopefully the ERC is not too hot for the tooling ... it seems most of the posts I have read suggest commercial hardwood which I understand is slower. I made a LOT or ERC charcoal years back, I had a truck full of bales from the pet store and sold a bit of it to make money to attend convention one year. It was fantastic and had a lot of power but now I just want it to be reliable 100% of the time. I also have 3/4" universal tooling (and something called Econo Tooling for 3.75" x 3/4" tubes, spindle shape looks like universal, fatter than core burn and a bit shorter). Anyway for the Universal and Econo Tooling I am considering 75:15:10 with ball milled ERC. The Econo Tooling is the result of a collaboration between caleb and I when I started the Cohete flights a few years back. I had asked Cal for tooling for the 5/8" tubes 3.75" long as well as the tooling for the 3/4" tubes. My wife uses the 5/8" tubes on her 3 ton arbor press and I use the hydraulic press on my 3/4" Cohetes. We alway make them without nozzles or bulkheads and fill them to the top of the 4" tube! They easily lift a 3 inch ball shell to an acceptable height but a 10g report is the most pleasing to most. If I were to try the Steve Laduke formula 60:30:10, I would ball mill 60:15:10 to get the fine meal, then add in 15 of 80-Mesh. Except I do not have commercial hardwood charcoal. If you make ERC charcoal, hardwood charcoal is just as easy to make. I also add 5-8% coarse charcoal to my fuel for a bushy tail and it eliminates the thrust drop when homogeneously mixed before corning. Oh! one last question...where do you fuse the core burn motors? I have been told that if you use quickmatch to get ignition at the top of the core, the motors take off like a bat out of hell. If you fuse it so the ignition is at the bottom of the nozzle, the power is greatly reduced but still functional. In other words, another way to control thrust is where you fuse the motor. Sorry, there is no free lunch in physics. You will get the same useable thrust measured as total impulse. The total impulse (I) of a rocket is defined as the average thrust times the total time of firing. So measure the thrust and the total time of firing for each example. Personally, I J-hook my core burners with Chinese visco and insert a flared end of Chinese visco into the nozzles of my end burners and use 4 strands of commercial Chinese quickmatch in the nozzles of drivers. So many variables! Thanks. Edited September 1, 2022 by dagabu 1
nordicwolf Posted September 2, 2022 Posted September 2, 2022 So much good info. Thank you. And thanks for the info on the cohete tooling. I have a few more questions specific to that. 1. what is "RUD"?2. for the 3/4"x3.75" tubes, how do you attach your stick? a single 36"x1/4x1/4? Or do you break it, say, 26" on one side and 10" on the other side? When I got the tooling from woody, I also got some 36x1/4x14 sticks3. Is it the same "stick strategy" if no header, 3" ball shell header, or 10g report header?4. how did you attach the 10g report? Was it a 1" ID tube slid over the end of the motor?5. do you wax tubes, cores, or anything special when using the 3/4"x3.75" tooling?6. do you press 75:15:10 the entire length of the tube? Or do you go to something slower for delay once you switch to the flat rammer?7. finally regarding your comment: I also add 5-8% coarse charcoal to my fuel for a bushy tail and it eliminates the thrust drop when homogeneously mixed before corning." how does corning enter into this? I thought corning was the breaking up of a pressed puck of BP, so I do not understand the comment. Thanks again very much!
dagabu Posted September 6, 2022 Posted September 6, 2022 So much good info. Thank you. And thanks for the info on the cohete tooling. I have a few more questions specific to that. 1. what is "RUD"? Sorry, RUD = Rapid Unplanned Disassembly2. for the 3/4"x3.75" tubes, how do you attach your stick? a single 36"x1/4x1/4? Or do you break it, say, 26" on one side and 10" on the other side? When I got the tooling from woody, I also got some 36x1/4x14 sticks Naw, those motors just get one stick, about 24" long, 1/4" X 1/4". We use tarred string to attach sticks to the Cohetes. They stay tighter that any other method, period!3. Is it the same "stick strategy" if no header, 3" ball shell header, or 10g report header? Yes sir 4. how did you attach the 10g report? Was it a 1" ID tube slid over the end of the motor? Yes5. do you wax tubes, cores, or anything special when using the 3/4"x3.75" tooling? Nope, I tried all that stuff with absolutely no difference found in the end, dry tubes, dry spindle. 6. do you press 75:15:10 the entire length of the tube? Or do you go to something slower for delay once you switch to the flat rammer? 75:15:10 all the up, including the delay of 1 ID above the spindle, adjust as necessary.7. finally regarding your comment: I also add 5-8% coarse charcoal to my fuel for a bushy tail and it eliminates the thrust drop when homogeneously mixed before corning." how does corning enter into this? I thought corning was the breaking up of a pressed puck of BP, so I do not understand the comment. Corning is my word for making grains by pushing the whetted BP ball through the 1/4" mesh. Not sure what the right word is. Thanks again very much! 1
nordicwolf Posted September 16, 2022 Posted September 16, 2022 I have a bunch of 1/4" x 36" square dowel sticks. If I were to use 24" lengths with 3/4"x3.75" cohete tubes, what can I do with the 12" left over? Can I glue and tape two 12" lengths together and use that as a "24 inch" stick on another cohete rocket? Thank you.
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