NeighborJ Posted October 24, 2016 Share Posted October 24, 2016 Usually if an inhibitor sleeve is used to protect the case it will prevent any casing damage. If it still burns the case near the nozzle it is a sign of incomplete, initial ignition, meaning the bottom of the core lights and then travels up the core. This will cause the case to be exposed to combustion gasses near the end of the burn and loss of impulse thruought the burn. If this is the case there are several remedys depending on ignition method. If no sleeve was used then I'd strongly suggest using one. Link to comment Share on other sites More sharing options...
Redrocketman Posted October 25, 2016 Share Posted October 25, 2016 I'm lucky, where I live in basically free launch anything ( & I do!!! ) but I have clear airspace, no flight paths for miles, and no people around to annoy. If you live in a densely populated area or air traffic & or regulations/ restrictions exist, it is simple common sense to join a clubIn relation to your experimentation, awesome!!! I am now heavily involved in AER, and as you said, the goal is to design, fabricate & fly rockets using readily available, cost effective materials, rather than buying commercially available kits & accessories. I was recently told, model/kit rocketry is for those who want to fly rockets, AER is for those who want to make rockets fly.Safety and common sense MUST ALWAYS be no 1 priority. Link to comment Share on other sites More sharing options...
carbonhalo Posted October 25, 2016 Share Posted October 25, 2016 Most of my state is controlled airspace. I live in class E, with a class C boundary 200m away. I'm also only 10km from both a class G area and a class R restricted airspace. High altitude is not something I aim for in launches. Link to comment Share on other sites More sharing options...
NeighborJ Posted October 25, 2016 Share Posted October 25, 2016 One thing we've noticed at my club is, the moment we get altitude clearance the local small planes and helicopters seem to gravitate to our little portion of restricted air space. It appeals to the curiosity of the private Sunday fliers. We will not launch if a plain is in sight and it becomes an annoyance as they fly directly over our launch sites. Apparently they can fly over because they don't need a flight plan. Sometimes I think it would be safer if we wouldn't need to announce our presence with the clearance. Link to comment Share on other sites More sharing options...
OldMarine Posted October 25, 2016 Share Posted October 25, 2016 I guess light plane pilots don't realize a pvc rocket would punch a hole in parts of their planes. They're not sidewinder missiles but the planes aren't A-10 wart-hogs either. Link to comment Share on other sites More sharing options...
sitas Posted October 26, 2016 Share Posted October 26, 2016 Old Marine, you hit the nail on the head. As a user of these rockets I know what they are. The outside ,unconcerned public just don't get it . Standing in front of one of my small motors would be a kin to standing in front of a 12 gauge. My motors are made from sked. 40 pvc pipe, 6" long. Thats a bunch of propellant.While testing I've had them go through a galvinized garbage can. In and out.At close range--ya, but even so.When the guys were talking about high power motor ignition, all the ones I'm familiar with are lit from the top . They push the electric fuse all the way up to the top from the bottom.Strange but it seems to work the best. Getting a high power right is not done in one shot . A motor is one thing , getting the balance right is a nother matter.These things are as tricky as your pyro rockets .Maybe more so ,cause all the extra size and weight.Not as costly for your body parts though.Ya , we'll get an occasual cato,---but, not in your hand. Much different results.I didn't know any better, thats why I ended up here. I wanted to talk rockets, and ended up learning enough to really wake me up. The real thing here is the fuel . Awesome Link to comment Share on other sites More sharing options...
douglas423 Posted October 26, 2016 Author Share Posted October 26, 2016 https://www.youtube.com/watch?v=H4q3NPrKHEoA wideo of someone having similar idea.What is your point? he was using a pvc casing and aluminum in the fuel. Link to comment Share on other sites More sharing options...
douglas423 Posted October 26, 2016 Author Share Posted October 26, 2016 Safety is always my number 1 priority when my fuel testing and will be with every step. The day after i received my order or AP and aluminum i began to test a small batch of about 7g of fuel which put rcandy to shame! i'll hopefuly post a video tmr with around 86grams of the APCP tested in my rocket body. I have realized i HAVE to use a sleeve on the fuel so it doesn't melt the casing like last time(with a failed fuel). As goes for airspace i will look into info about where i plan to launch it. Its farm land that my family owns many miles past anywhere. Link to comment Share on other sites More sharing options...
douglas423 Posted October 26, 2016 Author Share Posted October 26, 2016 Old Marine, you hit the nail on the head. As a user of these rockets I know what they are. The outside ,unconcerned public just don't get it . Standing in front of one of my small motors would be a kin to standing in front of a 12 gauge. My motors are made from sked. 40 pvc pipe, 6" long. Thats a bunch of propellant.While testing I've had them go through a galvinized garbage can. In and out.At close range--ya, but even so.When the guys were talking about high power motor ignition, all the ones I'm familiar with are lit from the top . They push the electric fuse all the way up to the top from the bottom.Strange but it seems to work the best. Getting a high power right is not done in one shot . A motor is one thing , getting the balance right is a nother matter.These things are as tricky as your pyro rockets .Maybe more so ,cause all the extra size and weight.Not as costly for your body parts though.Ya , we'll get an occasual cato,---but, not in your hand. Much different results.I didn't know any better, thats why I ended up here. I wanted to talk rockets, and ended up learning enough to really wake me up. The real thing here is the fuel . AwesomeFuel is pretty costly as for APCP where one pound the ammonium perchlorate cost me $11! I gotta waste little to none and still be able to launch. I burned 2.4grams of the fuel and it was a pretty powerful thing of fuel. Link to comment Share on other sites More sharing options...
gdeputy Posted October 26, 2016 Share Posted October 26, 2016 (edited) You're totally missing out, i'm telling ya... Go to a tripoli research launch. See big rockets. Meet people and get help to build some fun stuff.Big rockets likehttp://www.blastzone.org/images/fits2010/htmready_small.JPG and http://www.blastzone.org/images/fits2010/htmlaunch_small.JPG Or static testing motors and collecting data is fun too http://www.blastzone.org/images/75mm6000testsmall.jpg Static test of a 6" diameter motor i did years ago... https://youtu.be/3BBaVA5t7Bw These last two are motors/propellant i built myself, not commercial motors. Edited October 26, 2016 by gdeputy Link to comment Share on other sites More sharing options...
douglas423 Posted October 26, 2016 Author Share Posted October 26, 2016 One problem for launching with a local group(Tenseness) the next launch is in 136 days.. I will look into it more and launch a rocket with them tho. Link to comment Share on other sites More sharing options...
douglas423 Posted October 28, 2016 Author Share Posted October 28, 2016 (edited) That is a video of what i did tonight. It failed and blew out the side after i tried repairing it last time. It had no inhibitor sleeve but my next one will.... Hard lesson learned. This was only 83 grams! and burned for about 10 seconds real time. And to the people above that said there would be some erosion from it due to it being a aluminum nozzle. There is little to none difference from the nozzle before and after! Ill post photos tmr. I'm pretty busy with school so I'm not able to do it as much. Edited October 28, 2016 by douglas423 Link to comment Share on other sites More sharing options...
gdeputy Posted October 28, 2016 Share Posted October 28, 2016 What Kn are you running at? Any idea on chamber pressure? 10 seconds is a loooooong burn, without an insulator it'll be tough to keep it from burning through. At a typical chamber pressure with APCP an aluminum nozzle will fail in a very short time. Aluminum is commonly used in the fuel, and the propellant will happily consume an aluminum nozzle as fuel. 1 Link to comment Share on other sites More sharing options...
NeighborJ Posted October 28, 2016 Share Posted October 28, 2016 From the vid it seems that something is going on with ignition. The exhaust seems to waver from side to side before the case rupture. After a case failure at around 3-4 seconds the fuel will burn very slow due to the low case pressure. I believe even slight erosion will cause the side spitting exhaust as well, this has previously caused many issues with my rockets until the kind folks here helped me work out what was wrong. I'm curious how are you igniting the core? Link to comment Share on other sites More sharing options...
douglas423 Posted October 28, 2016 Author Share Posted October 28, 2016 I'm not sure of the pressure or force but I will test that soon. I believe the flame seemed to go up and down because I just had the motor in a rock pile covered. I was using a long burn wick to light it. The rocket didn't fail because of the nozzle at all. The nozzle worked perfectly with little to erriosion. I will post photos later. It failed as I stated above from a previous small hole in the motor casing. I tried using a bigger end cap on it but it still was to much stress and created a weak area. I have since then cut t off and will real Machine a motor casing. I'll post a test this coming week. But the nozzle being aluminum is working fine and bkt melting or anything at all. Link to comment Share on other sites More sharing options...
dagabu Posted October 30, 2016 Share Posted October 30, 2016 Gdeputy is spot on! Ill add to his comments, if you use an aluminum nozzle and it DOESN'T melt out, your fuel is extremely under powered. Douglas, we are experienced HP rocket builders, we are not feeding you a line with our advice, we are telling you things that will significantly shorten your research time and allow you to make working motors very quickly. And BTW, $11:00 a pound is pretty good for single pounds of AP, you could do worse. Bulk pricing is $4.00 a pound when you buy a drum. Link to comment Share on other sites More sharing options...
MadMat Posted October 31, 2016 Share Posted October 31, 2016 (edited) I have a thought for any of you experienced high power rocketeers. Has anyone ever given thought to using hard-coat anodized aluminum for nozzles? My thinking; if used with an aluminum rocket casing, the thermal conduction might keep the nozzle from melting. The hard-coat anodizing, if made thick enough, would definitely be up to the task of holding up. Not to mention, anodizing aluminum at home is very doable. Just a thought. Edited October 31, 2016 by MadMat Link to comment Share on other sites More sharing options...
Arthur Posted October 31, 2016 Share Posted October 31, 2016 Lots of the rockets (well missiles really) at the local ERDE museum are sectioned and inert and the nozzle is graphite and it's held in place with an asbestos loaded thermosetting resin. Link to comment Share on other sites More sharing options...
gdeputy Posted October 31, 2016 Share Posted October 31, 2016 That is a lot of machining time and cost for a nozzle where graphite is cheap, easy to machine, and works great. I'm confident any aluminum nozzle, anodized or not, will fail with an apcp motor that runs at any reasonable chamber pressure and burn time. Especially at the throat. I have built aluminum nozzle carriers that have a graphite throat and an aluminum expansion cone farther down, and those can work. Again with longer burns things get awfully hot, though. Link to comment Share on other sites More sharing options...
douglas423 Posted October 31, 2016 Author Share Posted October 31, 2016 I recently looked into getting a graphite rod for a nozzle and will probably go with that on my next one. I don't want a real long burn time on this rocket. It's a proof of concept but i will probably machine the next one out of graphite. My aluminum now is very thick more than 1/4" on the thinnest part. Link to comment Share on other sites More sharing options...
NeighborJ Posted October 31, 2016 Share Posted October 31, 2016 (edited) Douglas, if you want a proff of concept, it is entirely acceptable to turn the nozzle from steel. As long as you do your testing in a safe manner so if it catos it will be protected by sand bags. You don't want a projectile of steel flying into a populated area. After testing you can switch back to the graphite nozzle for flight. Edited October 31, 2016 by NeighborJ 1 Link to comment Share on other sites More sharing options...
sitas Posted November 1, 2016 Share Posted November 1, 2016 Hey guys, on the subject of aluminum motors. What are they using for fuel in the factory made motors. They are aluminum and anodized. Maybe they have something else for a nozzel though. Graphite maybe? I see them on sale in a lot of places. You just drop in the inserts and fly them. Link to comment Share on other sites More sharing options...
douglas423 Posted November 1, 2016 Author Share Posted November 1, 2016 I would have used steel for the nozzle but the fact I don't have a metal lathe made it hard to do. I turned the aluminum on a wood lathe without a chuck. Steel would be impossible on it. I can't just spend $700+ just for the nozzle. I will order some graphite to try and turn since it will be probably a lot softer than aluminum. I'm testing the nozzle again later tonight. I'll take a video and include the photos from the last test and the test tonight of the nozzle. Link to comment Share on other sites More sharing options...
gdeputy Posted November 1, 2016 Share Posted November 1, 2016 Hey guys, on the subject of aluminum motors. What are they using for fuel in the factory made motors. They are aluminum and anodized. Maybe they have something else for a nozzel though. Graphite maybe? I see them on sale in a lot of places. You just drop in the inserts and fly them. They use the same APCP propellant we're discussing here. The reload kits use cardboard and/or phenolic liners to protect the motor case. Nozzles are most commonly made from phenolic (Aerotech and Cesaroni reloads) and are single use. Some others manufacturers (like Loki) use Graphite nozzles that are good for multiple uses. Link to comment Share on other sites More sharing options...
douglas423 Posted November 1, 2016 Author Share Posted November 1, 2016 Does anyone know where i can possible get a graphite rod around 2.5"-3" for not a ton of money? Link to comment Share on other sites More sharing options...
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