That has got to be the tightest spike I've ever seen. That's an accomplishment in itself, but I don't think that design is scalable. It may sound crazy, but being TOO accurate tends to lead to catastrophic failure at ~10-15 TIMES scale model.
instead of focusing the heat proof material, can you redesign, the exit of combustion chamber and to direct the flame flow in the way that don't accumulate to much heat??
if you can, machined the spike in side the combustion chamber, perhaps the flame and temp can distribute faster and evenly.
So this "aerospike" theory has been tested for like ever. What exactly is the problem? We don't have the materials to withstand the heat yet or something?
Excellent video. If only all schools funded experimental research like this! When I was an undergrad, I had to pull teeth to get minimal funding. It was pathetic. The system didn't deter me, it inspired me to get things done. I turned to home experimentation. Since I didn't have funds for liquid engine testing, I turned to solid propellents. Learning how real rocket science works is beyond fun.
@sslayer0117 it all depends on what you want to do, you can buy kit rockets that'll range from $50 to thousands...or you can build from scrach, a lot more fun, but takes way longer and will probably cost more than a kit. But either way is a lot of fun.
@earthstation1 that is steel....chrome-molly. The second nozzle is made from stainless steel. Which is a little better in terms of the melting temperature, but the redesign is what fixed the issue. If I had more time and money I'd have gone ceramics. Thanks.
all aerospike nozzls/engines are doomed to failure unless 1> unknow advanced materals are devised to handle the heat stress . 2> active cooling is employed
3> laminar sheeth of insulating gas over critical componants that atleast works on 1st stage to leo .
have you tried inconel btw ? x15 was covered in the stuff
@1abcrr1 True for sustained burning of an engine. But in my case, this video is of the smaller scale version of my nozzle for classroom demonstrations. I designed a full rocket motor around a bigger nozzle that would have lasted several minutes without any cooling or exotic materials...just wasn't able to use NOS during this time frame to test it... :( Inconel would have been fun, but sadly no..
I'm working on creating a high powered rocket, although for the time being I am in the design and prototype stage. I was wondering what the cost of the machining was? I plan to have my nozzle machined (be it a bell or aerospike, most likely bell, or perhaps angular), and I would like an estimate on how much the machining cost you.
@KittyRokher Thanks...well I machined this myself using the school machine shop, so I only had to cost of the materials...but each nozzle took over 30 hours of machine time. A bell nozzle however should be a lot faster to make on the lathe, probably looking at around 4-10 hours depending on the size. Hope you can find a shop that doesn't charge a lot to use their machines...
the pulses you experenced in the test jig were due to resonant pulsing, much like a pulse jet - as mean pressure on exaust raises it does so at nearly the speed of sound the tube (combustion chamber) sets the frequency of the pulse and the high inlet ox/fuel
means there is no need for shutters , the only thing needed for plasma sound reverberation is pressure ,hence pulsing-------solve pulsing by makingpressure sensitive relief valving in the direction of exaust stream (co laminar)
@badboybilzer True, but I think the issue was more switching over from starting with propane to oxygen...there was probably some 'air' in the lines along with pressure differences. However, I did have this problem with other hybrid motors that I was working on at the school. Thanks.
Hi, Since viewing your video I've done a small amount of reading on aerospike's. The few engines I've seen have been wildly different in design (the X-33 linear, a demo annular and of course yours). The reason I bring this point up is to determine if you were able to achieve the goal of an aerospike (what I'd call less span-wise flow as a former pilot of swept wing aircraft) or reduce the expansion that occurs in bell shaped exhausts.
@johnmresler Thanks for looking...but to answer your question, my tests were unable to demonstrate the differences between an aerospike nozzle vs. a regular bell nozzle. The best I could hope for (since the engine never will take flight) is to match what the regular nozzle can achieve. The real benefit to the aerospike is better overall thrust performance throughout the whole atmosphere, where the bell nozzle is really only efficient in a small band of the atmosphere. Hope this helps.
Okay sorry for breaking the party but this was sort of dangerous. Because you used a 611 gas tank, with a high pressurization air tank, with a Hybrid Rocket Motor Aerospike Nozzle, if there was any mis calculations, it was going to be KABOOM! In your testing area. Luckily nothing wen't wrong. But great job.
Rockets are always dangerous no matter what size they are, this fact isn't neglected at this school, in industry or anywhere that wants to get into rocket science. Safety planning is heavily looked into before anything is attempted like this at Cal Poly. But ease your concerns, this set up is not as dangerous as you may think. Neither is the use of NOS, but back in '07 in the Mojave Desert there’s a company that got surprised with its use, however they are still using it today.
@grumm70 This particular set up is much too small to be cut into smaller pieces...but the problem with doing that would be containing the exhaust pressure, if any were to find its way out of the nozzle other than in the intended exit, then that’s when it'd go kaboom. Though it'd fun to try.
ok your going to have to use titainum with ceramic coating or use the nozzle you have to cast a ceramic nozzel from ether sand or clay, eather way its going to have to be ceramic or coated, David Coffin*
Makes me think of a number of the old science fiction stories of yesteryear. In them, the hero-genius somehow manages to discover an alloy completely immune to heat, but which can still be machined.
I guess that's what you engineering types call "unobtanium", eh?
Makes me think of a number of the old science fiction stories of yesteryear. In them, the hero-genius somehow manages to discover an alloy completely immune to heat, but which can still be machined.
I guess that's what you engineering types call "un-obtanium", eh?
@jpourkav graphite was used by Germans in WW2 on the V2 rocket on the basis that in the flame it is no oxygen so the graphite will not ignite and burn. Englishmen can certify that the system worked.
@MarkieSKII This test was for feasibility. Hot fire testing of an aerospike nozzle at Cal Poly has been attempted only a few times. I wanted to prove that it could be done successfully, but the main project behind the testing was to produce a working computer model of the nozzle. For if the model says one thing and your actual motor produces another, then something is way off, but if they are close, then you can scale up from small to big rockets, eventually leading back into flights.
That's about the temperature range I figured, given the conditions of that experiment. Yes there are lots of choices of materials, this I know, I was just giving you a choice that you can find as scrap, and is used in rocket nozzel applications extensively. Very cool though, carry on, and if you need maching let me know :)
From countless days using MatLAB writing code for the Method of Characteristics...google that sometime and you'll find just how vast two simple equations can be quite troublesome to solve.
I'm not sure exactly what your asking/thinking, but with the right materials, anyone can make a hybrid rocket which has no moving parts, so actually this isn't a machine at all. :)
Ah, ok. Well, it was pretty simple, mostly just a lathe, with some minor milling to make the holes. Other than that it took a lot of time, nearly 35 hours to machine.
The propane is used as an ignition source. you just can use a spark plug since you need to touch the grain. A squib works, but here at Poly a quick turnaround is beneficial.
First we ignite the propane with a spark plug because this can be done easily, so once thats lit, we then transition to the gaseous oxygen (GOX) which is the oxidyzer which this then needs the plexglass as the fuel source. Propane contains its on oxidyzer and fuel, which makes it easy to ignite, just like in a bbq.
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hybrid rocket is what we need now.. you guys could get a lot of money, because if there a hybrid rocket, then planes could start using those and the world wont have as much polution and we can also save more gas..
Maybe true, however rockets consume larger amounts of fuel than a jet engine can. Scram jet engines, like the ones used on the SR-71, are the nearest resemblence of a sudo rocket engine, yet still no where near a powerful. Plus taking off with those engines from LAX would blow out all windows within a 5-10 mile radious.
you should maybe take a more heat resistant material. Did you measure out the nozzle´s temperature? You can do touchless to save your equipment via IR. Maybe you also can add a surface coating that burns away to get rid of temperature on the nozzle... Just thinking...
Yep, if I had more time I would have done such tests as you spelled out. No actual measurment was ever taken, but my best guess would put the exhaust temp between 2,500-3,000 degrees F, based upon how quick the material melted away.
i need to go to cal poly, i'm a sophomore in HS and cal poly is local.
i've been to a few of their "open house" things, and it's amazing, they have a flight simulator, a full machine shop with like 3 cnc machines, rapid prototyping machines, and they even have a surfboard shop... it's fucking amazing!!!
Thanks. And yes there are a lot of mills and lathes laying around, some accessable by all students and many are only for use within each students major.
@kyle1058 Thanks, Cal Poly SLO is a great place to go to and be at. Lots of hands on projects, and you have the freedom to invest your time into whatever you wish with all the backing and support of the professors.
No one was really sure what the temperature actually was, so I went with what I was able to afford and get quickly, there's tons of possibilities of materials to use. However, a quick estimate of the temperature, I would say that it probably reached between 2,500-3,000 degrees F.
i think the idea is that once you get to outer space you don't need a bell housing you need a housing of a different shape on the rocket engine so with this thing you can get more thrust but im probab wrong im a business major
My understanding is NASA has always had to compromise on nozzle shapes. Air pressure affects the efficiency of the design. Ideally a variable shaped nozzle would increase the efficiencies from sea level on up as air pressure decreases.
Yes, this type of nozzle shape would be more efficient in space over a regular bell nozzle. However, it is also more efficient while in our atmosphere as well, but the only problem is that the nozzle is surrounded by the hot exhaust, therefore actually getting one to work for say the space shuttle would be very very hard. NASA did look into this nozzle shape a long time ago and they have yet to figure out a way to use it, other than it being linear.
Would it be possible to email this from a personal email to a high school email address...I'm a high school teacher and my HS email won't allow me to access youtube. I would like to show this to my students.
This might be too large to send by email, however there are a lot of programs you can find that can save any youtube video, in which you could then burn it onto a dvd to show in your classroom.
I thought that I said that this produced thrust in units of grams...I'll have to go back and check and make that more clear. This is a very scalled down class demonstrator, so our professor and the school won't allow for anything larger than a few pounds of thrust.
Hey, very good video. I want to get into rocketry, and am probably going to design a hybrid rocket soon. I live near that school, and have heard about it a lot. Our schools robotic team is in the same competition as yours, our school is Samammish. It would be nice if I could come out and see one of your rockets in action.
The rocket club meets every saturday around noon, drive up to the baseball fields and walk to the hanger (its an actual aircraft hanger) and ask anyone where the rocket club (CPSS) is at.
A standard rocket nozzle, the bell shape, is optimised to a particular altitude; in other words, the efficiency depends on the outside air pressure. This is bad, because as your rocket goes up through the atmosphere, the pressure drops, so the rocket gets less efficient. An aerospike engine is as efficient at ground level as in the upper atmosphere, so it takes less fuel to get into space, so your rocket can be smaller, so the payload for a given rocket can be bigger, and cheaper to launch.
Thats so you can see the combustion, otherwise you would only see the fire coming out the end and not it swirling around inside. I don't think the videos give it justice as to seeing it in real life.
Clearly you are unaware of our full scale hybrid motor...LOL.
Kidding aside, our hybrid isn't an annular aerospike yet. Soon, the next phase I believe is a cooled spike annular aerospike hybrid motor. At the moment we have full scale cold flow aerospike and a cooled throat hybrid motor. Both on the order of 300 psi operating pressure.
Thanks. I did do that a littlebit. But this one was just for my teacher, my real motor that I was building the school wouldn't let me fire it, after the Scaled Composite accident back in the summer of 07.
Did they ever conclusively determine what exactly caused the cold flow accident in Scaled composites? I suspect the N2O they used hit some catalytic metal like nickel and their composite fiberglass tank pressure got too high. I think they now realize it pays to have a burst disk on those things.
Your right, 400 grams = ~ 1 pound... not very much at all, but this is just for demonstartion and I had too much to try to build and get working that I couldn't modifiy the components of the pre-existing rocket. I did build a 100 pound aerospike, but wasn't able to test it.
this is all awesome, i wish my uni had an aerospace program. i've never seen a transparent motor casing before, what pressure will it hold and could it burn through?
i was trying to research aerospike nozzles a few months ago but i googled up next to nothing.
i decided to make conventional conical nozzles from porcelain [after-hours artschool aerospace =D] and i'm nearly ready to test one, but i'd still be fascinated to see your drawings and get a handle on the design considerations!
Thanks for the comment. Well, this setup can only support about around 120-150 psi of O2 before the combution leakes out between the o-rings. It would be posible to have this be much greater, but that would require it to be redesigned.
As for finding information, if you can access AIAA, they have everything that I used. And if yor associated with a school, you should be able to have access to AIAA, at least it was when I looked through them a year ago.
Very nice video. I like the use of plexiglass (polycarb or acrylic?) for the combustion chamber.
I have a few questions:
1) After the ignition for a few seconds there is a squeal and the combustion regime is different. Is this because you are ramping your O2 up until you choke?
2) Ever consider using an inconel-series metal? Say 718? The stuff is a biznitch to machine though with the proper cutting tools you will get superior results.
Thanks, glad you liked it. Yeah, thats why this uses the plexiglass as the comb. chamber so that it internal mixing can be viewed, although it makes it very bright. As for the instability, that is the propane dancing around, it probably has to do with not enough oxygen to burn since its not only burn itself but the plexi fuel aswell, ie very fuel rich. The oxygen is the bigger 'puff' in which its a pretty stable burn afterwards. As for the metal, I dont remember if I looked at that one or not.
And as for the BC, I'm not too entirely sure as to what they were, I wrote 2 programs, both of which were vastly different. The major program that was used for the tested design was purchased and I had no control over those parameters. Sorry I couldn't be more helpfull.
hey bro that was a nice video ,,,,am just wondering ,why don't you use titanium wouldn't be stronger , lighter ,and it can take so much heat before it melts ,,,take care
I looked into it, but from what I found, the temperature increase was only about 3-400 degrees C. So it would still have a hard time withstanding the temperature. As for its other qualities, this is a test nozzle, so the strengh and weight arnt very relavent to the testing. If I were to make this a flight test, then yes I would have looked into Ti a lot more. And it would have cost about 12-1500 dollars too, way to much for a senior project. But thanks for the suggestion.
Well an aerospike nozzle or aka a plug nozzle is pretty much an inverted rocket nozzle. A normal nozzle compresses the exhaust toward the center of the nozzle before expanding it back out again. The spike nozzle is more like a garden hose spray nozzle. Instead of defining the outer walls like the normal nozzle does, the spike nozzle only defines one wall and uses the atmoshpere as the other adjustable wall, therefore making it more efficient in terms of under or over expanding the flow.
Well, I'm not too sure if you would be able to access it from Cal Poly's web site, posibly. But I don't think I'll be submitting it anywhere else, like AIAA or anything. My report only has a few detailed drawings of the spike geometery, then its mostly concerning the results of my 3 test fires.
Well, there are many books and websites devoted to the Method of Characteristics that you can look at if you really wanted to get lost in all the math to understand how it works. As for giving away my program, its not that user friendly and would probably be hard to understand, I know that I don't even understand how it all works.
Well, I wrote two computer programs to design the shape, one using simple geometry and the other using method of characteristics. I also purchased a design program from AeroRocket Technology which also uses method of characteristics. I used each program to design nozzles that were tested in cold flow tests befor designing the hot flow nozzle. As for a combustion model, I did not perform any CFD analysis. If I had I could have submitted this for a Masters Thesis instead of just a Bachlors. :)
The propane is only used to ignite the oxygen, it may also react with the plexiglas fuel grain but only very little. Once the propanes burn is at steady state, the pulsating in the first attempt, then the oxygen is injected and the propane is turned off. The propane provides a hotter flame to ignite the oxygen than the spark plug that ignites the propane. The Oxygen then burns with the plexiglas. Thanks for the comment.
Try streamlining those spokes. gas friction at that speed makes even more heat. the more streamlined, the better for less resistance to the flow. also it might make it more powerful by cleaning up the flow stream
Yeah, thats pretty much what happened, and thats what the second nozzle was designed for. The three holes were more streamlined than the 'wagon spokes' which caused stagnation areas in the flow, heatting it up beyond the normal exhaust temperatures. Thanks for the advise.
good job doug. similar concept to the aerospike nozzle i machined 2006. just presented it at the 2008 AIAA student conference and took first. my close friends and i are working on the new ones now. keep up the good work.
Cool, thanks. Yeah, that was my small nozzle, my school wouldn't let me use NOS which I had for my larger, ~100 lbf aerospike. I have it all machined up, just need NOS to fire it off.
yeah... when i did mine, it was already a personal project and found out i could turn it into a independent study at the university. so, i had already purchased all the equipment. they did though offer supplies when i signed up for the independent study. why wont they let you use N2O ?????
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That has got to be the tightest spike I've ever seen. That's an accomplishment in itself, but I don't think that design is scalable. It may sound crazy, but being TOO accurate tends to lead to catastrophic failure at ~10-15 TIMES scale model.
bamboo4tameshigiri 2 months ago
make a tutorial its amazing
macintosh39 4 months ago
question?
instead of focusing the heat proof material, can you redesign, the exit of combustion chamber and to direct the flame flow in the way that don't accumulate to much heat??
if you can, machined the spike in side the combustion chamber, perhaps the flame and temp can distribute faster and evenly.
gmrwawa 4 months ago
Wish i could go to college for shit like this, unfortunately i blow at math.
seldian 4 months ago
So this "aerospike" theory has been tested for like ever. What exactly is the problem? We don't have the materials to withstand the heat yet or something?
rasmasyean 4 months ago
Excellent video. If only all schools funded experimental research like this! When I was an undergrad, I had to pull teeth to get minimal funding. It was pathetic. The system didn't deter me, it inspired me to get things done. I turned to home experimentation. Since I didn't have funds for liquid engine testing, I turned to solid propellents. Learning how real rocket science works is beyond fun.
skyguy1977 4 months ago
Would a different material, like Inconel, help?
murdelabop 4 months ago
Very cool. Thanks for sharing!
Miata822 7 months ago
@Miata822 Thanks.
ragobgar 5 months ago
Using a clear polythene pipe was a pretty awesome idea. Absolutely beautiful when its running.
luketorpedo 8 months ago
@luketorpedo Its a whole lot better in person, really interesting too looking through polarized glasses... :) the fire almost looks alive.
ragobgar 5 months ago
Ok so here lately i have been looking into rockets a lot how much money and time would it take to make one of these?
sslayer0117 8 months ago
@sslayer0117 it all depends on what you want to do, you can buy kit rockets that'll range from $50 to thousands...or you can build from scrach, a lot more fun, but takes way longer and will probably cost more than a kit. But either way is a lot of fun.
ragobgar 5 months ago
What an excellent project. Are you now working in aerospace?
metimmee 8 months ago
@metimmee Thanks, and yes I am, in flight test.
ragobgar 5 months ago
the sparks are coming from the aluminum melting internally You need to redo it out of steel you might try ceramic's they will indure the heat better
earthstation1 11 months ago
@earthstation1 that is steel....chrome-molly. The second nozzle is made from stainless steel. Which is a little better in terms of the melting temperature, but the redesign is what fixed the issue. If I had more time and money I'd have gone ceramics. Thanks.
ragobgar 5 months ago
the sparks are coming from the aluminum melting internally You need to redo it out of steel
earthstation1 11 months ago
Engine gets too hot, it will fail
Dre4dwolf 11 months ago
all aerospike nozzls/engines are doomed to failure unless 1> unknow advanced materals are devised to handle the heat stress . 2> active cooling is employed
3> laminar sheeth of insulating gas over critical componants that atleast works on 1st stage to leo .
have you tried inconel btw ? x15 was covered in the stuff
1abcrr1 1 year ago
@1abcrr1 True for sustained burning of an engine. But in my case, this video is of the smaller scale version of my nozzle for classroom demonstrations. I designed a full rocket motor around a bigger nozzle that would have lasted several minutes without any cooling or exotic materials...just wasn't able to use NOS during this time frame to test it... :( Inconel would have been fun, but sadly no..
ragobgar 5 months ago
Very cool stuff. Amazing the erosion resistance the stainless seems to have over the ChroMo.
762gunr 1 year ago
@762gunr Hard to really tell the difference since the design of the nozzle changed...but it was fun to watch none the less.
ragobgar 5 months ago
Fantastic. Awesome!
MateusSponch 1 year ago
@MateusSponch Thanks.
ragobgar 5 months ago
did you try graphite?
FTWMikeDero 1 year ago
@FTWMikeDero Didn't have enough time to try it. Would have been my next step.
ragobgar 5 months ago
I'm working on creating a high powered rocket, although for the time being I am in the design and prototype stage. I was wondering what the cost of the machining was? I plan to have my nozzle machined (be it a bell or aerospike, most likely bell, or perhaps angular), and I would like an estimate on how much the machining cost you.
Thanks!
Great design, by the way. You should be proud.
KittyRokher 1 year ago
@KittyRokher Thanks...well I machined this myself using the school machine shop, so I only had to cost of the materials...but each nozzle took over 30 hours of machine time. A bell nozzle however should be a lot faster to make on the lathe, probably looking at around 4-10 hours depending on the size. Hope you can find a shop that doesn't charge a lot to use their machines...
ragobgar 5 months ago
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perplexfraction 1 year ago
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lavernedi 1 year ago
Try using inconel type alloys
telesniper2 1 year ago
y put all that effort into something which is gona b destroyed?
wetdogpawseeeeeeeeey 1 year ago
@wetdogpawseeeeeeeeey to learn
hamguy01 1 year ago
@wetdogpawseeeeeeeeey Yes, but you learn from destruction, thus the redesign which worked perfectly....just one of many ways to truly have fun.... :)
ragobgar 5 months ago
he should use magnets so there is minimal contact
joustinApe 1 year ago
woah thats beast. you should try a coating of ceramic to combat the heat
TheDragonsword123 1 year ago
@TheDragonsword123 twas the next step. Thanks.
ragobgar 5 months ago
the pulses you experenced in the test jig were due to resonant pulsing, much like a pulse jet - as mean pressure on exaust raises it does so at nearly the speed of sound the tube (combustion chamber) sets the frequency of the pulse and the high inlet ox/fuel
means there is no need for shutters , the only thing needed for plasma sound reverberation is pressure ,hence pulsing-------solve pulsing by makingpressure sensitive relief valving in the direction of exaust stream (co laminar)
badboybilzer 1 year ago
@badboybilzer True, but I think the issue was more switching over from starting with propane to oxygen...there was probably some 'air' in the lines along with pressure differences. However, I did have this problem with other hybrid motors that I was working on at the school. Thanks.
ragobgar 5 months ago
This is bad-ass.
darklight5555 1 year ago
@darklight5555 Thanks.
ragobgar 5 months ago
Is that acrylic?
deaftodd 1 year ago
@deaftodd Acrylic, plexiglass...just a few of its many names...
ragobgar 5 months ago
Hi, Since viewing your video I've done a small amount of reading on aerospike's. The few engines I've seen have been wildly different in design (the X-33 linear, a demo annular and of course yours). The reason I bring this point up is to determine if you were able to achieve the goal of an aerospike (what I'd call less span-wise flow as a former pilot of swept wing aircraft) or reduce the expansion that occurs in bell shaped exhausts.
Did you achieve the goal?
johnmresler 1 year ago
@johnmresler Thanks for looking...but to answer your question, my tests were unable to demonstrate the differences between an aerospike nozzle vs. a regular bell nozzle. The best I could hope for (since the engine never will take flight) is to match what the regular nozzle can achieve. The real benefit to the aerospike is better overall thrust performance throughout the whole atmosphere, where the bell nozzle is really only efficient in a small band of the atmosphere. Hope this helps.
ragobgar 1 year ago
Okay sorry for breaking the party but this was sort of dangerous. Because you used a 611 gas tank, with a high pressurization air tank, with a Hybrid Rocket Motor Aerospike Nozzle, if there was any mis calculations, it was going to be KABOOM! In your testing area. Luckily nothing wen't wrong. But great job.
mandunya 1 year ago
Rockets are always dangerous no matter what size they are, this fact isn't neglected at this school, in industry or anywhere that wants to get into rocket science. Safety planning is heavily looked into before anything is attempted like this at Cal Poly. But ease your concerns, this set up is not as dangerous as you may think. Neither is the use of NOS, but back in '07 in the Mojave Desert there’s a company that got surprised with its use, however they are still using it today.
ragobgar 5 months ago
@ragobgar
Did Rutan's crew ever figure out what went so horribly wrong that day? The big selling point of NOS was that it was supposed to be safe.
pinz2022 4 months ago
How about building it into more sections with tapered parts,
so you can just replace the damaged sections that way.
spark erode the blind tapers,
grumm70 1 year ago
@grumm70 This particular set up is much too small to be cut into smaller pieces...but the problem with doing that would be containing the exhaust pressure, if any were to find its way out of the nozzle other than in the intended exit, then that’s when it'd go kaboom. Though it'd fun to try.
ragobgar 5 months ago
ok your going to have to use titainum with ceramic coating or use the nozzle you have to cast a ceramic nozzel from ether sand or clay, eather way its going to have to be ceramic or coated, David Coffin*
david1513 1 year ago
@david1513 Yep you're right, and those would have been the next steps. Thanks.
ragobgar 5 months ago
yay 100th rate
5 stars, just for the hell of it
brandond707 1 year ago
@brandond707 Thanks.
ragobgar 5 months ago
you should try using graphite for the nozzle, it stands up to heat quite well...its what we use over here at Arizona State for most of our rockets
jpourkav 1 year ago 3
@jpourkav Yep, that was the next step, just didn't have enough time to implement. Though maybe now for a thesis...hum....
Thanks.
ragobgar 5 months ago
@jpourkav
Makes me think of a number of the old science fiction stories of yesteryear. In them, the hero-genius somehow manages to discover an alloy completely immune to heat, but which can still be machined.
I guess that's what you engineering types call "unobtanium", eh?
pinz2022 4 months ago
@jpourkav
Makes me think of a number of the old science fiction stories of yesteryear. In them, the hero-genius somehow manages to discover an alloy completely immune to heat, but which can still be machined.
I guess that's what you engineering types call "un-obtanium", eh?
pinz2022 4 months ago
@jpourkav graphite was used by Germans in WW2 on the V2 rocket on the basis that in the flame it is no oxygen so the graphite will not ignite and burn. Englishmen can certify that the system worked.
Lightspit 1 month ago
Okay ive got a question, whats the purpose? is it for flying? -in english please- :p
MarkieSKII 2 years ago
@MarkieSKII This test was for feasibility. Hot fire testing of an aerospike nozzle at Cal Poly has been attempted only a few times. I wanted to prove that it could be done successfully, but the main project behind the testing was to produce a working computer model of the nozzle. For if the model says one thing and your actual motor produces another, then something is way off, but if they are close, then you can scale up from small to big rockets, eventually leading back into flights.
ragobgar 5 months ago
Looks like a huge waste of time and funds to me.Wht not just make them out if graphite or ceramic, and not just burn nozzles up?
Answer: Their too expensive to experiment with.
Never mind... Good work men...
fishkiller4111 2 years ago
Dr. D put some pressure on us at CPSS to get the flight hybrid consistent to use as a 401 demonstrator next year. We are looking at 500 lbf thrust.
Alexpaths 2 years ago
@Alexpaths Assume.....how'd it turn out? sorry been away from this for too long..
ragobgar 5 months ago
That's about the temperature range I figured, given the conditions of that experiment. Yes there are lots of choices of materials, this I know, I was just giving you a choice that you can find as scrap, and is used in rocket nozzel applications extensively. Very cool though, carry on, and if you need maching let me know :)
davydiver 2 years ago
how did you calculate the spike? and the compression at the throat
raining0724 2 years ago
From countless days using MatLAB writing code for the Method of Characteristics...google that sometime and you'll find just how vast two simple equations can be quite troublesome to solve.
ragobgar 2 years ago
what kind of wonderfull machine is that:D? I would love having this!
vekteius 2 years ago
I'm not sure exactly what your asking/thinking, but with the right materials, anyone can make a hybrid rocket which has no moving parts, so actually this isn't a machine at all. :)
Thanks for the comment.
ragobgar 2 years ago
well thanks for the info but I was actually asking for the machine you use to make the parts:P but I found it out myself now;)
vekteius 2 years ago
Ah, ok. Well, it was pretty simple, mostly just a lathe, with some minor milling to make the holes. Other than that it took a lot of time, nearly 35 hours to machine.
ragobgar 2 years ago
Comment removed
hohohyhy 2 years ago
The propane is used as an ignition source. you just can use a spark plug since you need to touch the grain. A squib works, but here at Poly a quick turnaround is beneficial.
Alexpaths 2 years ago
And Yes the plastic burns...It is a hydrocarbon just like gasoline.
Alexpaths 2 years ago
First we ignite the propane with a spark plug because this can be done easily, so once thats lit, we then transition to the gaseous oxygen (GOX) which is the oxidyzer which this then needs the plexglass as the fuel source. Propane contains its on oxidyzer and fuel, which makes it easy to ignite, just like in a bbq.
ragobgar 2 years ago
way to demonstrate ignorance of simple principles.
aoeuaoeu100 2 years ago
Always trying to do my part...
ragobgar 2 years ago
ceramics...
Bonzoix 2 years ago
Yep, that was the next step...
ragobgar 2 years ago
This comment has received too many negative votes show
hybrid rocket is what we need now.. you guys could get a lot of money, because if there a hybrid rocket, then planes could start using those and the world wont have as much polution and we can also save more gas..
alexserra11 2 years ago
Maybe true, however rockets consume larger amounts of fuel than a jet engine can. Scram jet engines, like the ones used on the SR-71, are the nearest resemblence of a sudo rocket engine, yet still no where near a powerful. Plus taking off with those engines from LAX would blow out all windows within a 5-10 mile radious.
ragobgar 2 years ago
i wanna go to that school :(
panzuman 2 years ago
Keep trying and eventually you may make it in.
ragobgar 2 years ago
your add water cooling into
Nose Axis
Ms7734 2 years ago
Thats possible, however this nozzle is just too small to do that correctly. Not enought margin for error.
Thanks for the comment.
ragobgar 2 years ago
you should maybe take a more heat resistant material. Did you measure out the nozzle´s temperature? You can do touchless to save your equipment via IR. Maybe you also can add a surface coating that burns away to get rid of temperature on the nozzle... Just thinking...
himoroyden 2 years ago 6
Yep, if I had more time I would have done such tests as you spelled out. No actual measurment was ever taken, but my best guess would put the exhaust temp between 2,500-3,000 degrees F, based upon how quick the material melted away.
ragobgar 2 years ago
@himoroyden
Has anyone ever used ablatives to line a rocket nozzle as opposed to a re-entry heat shield?
pinz2022 4 months ago
Cool experiment and cool mills/lathes you get to make it on! Looks like one hell of a fun school!
kyle1058 2 years ago 7
i need to go to cal poly, i'm a sophomore in HS and cal poly is local.
i've been to a few of their "open house" things, and it's amazing, they have a flight simulator, a full machine shop with like 3 cnc machines, rapid prototyping machines, and they even have a surfboard shop... it's fucking amazing!!!
pixuma 2 years ago
Thanks. And yes there are a lot of mills and lathes laying around, some accessable by all students and many are only for use within each students major.
ragobgar 2 years ago
@kyle1058 Thanks, Cal Poly SLO is a great place to go to and be at. Lots of hands on projects, and you have the freedom to invest your time into whatever you wish with all the backing and support of the professors.
ragobgar 5 months ago
Inconel 718 would be a better choice material for this experiment. You should be able to find scrap.
davydiver 2 years ago
No one was really sure what the temperature actually was, so I went with what I was able to afford and get quickly, there's tons of possibilities of materials to use. However, a quick estimate of the temperature, I would say that it probably reached between 2,500-3,000 degrees F.
ragobgar 2 years ago
Beautiful engine. Looks like it's worth the research. Guess it still requires heat sinks, hearing the scientist worries about burning it up.
bluemensch 2 years ago
Heat sinks or active cooling...thats for sure. I just didn't have enough time to try testing the use of either...
Thanks for the comments.
ragobgar 2 years ago
i think the idea is that once you get to outer space you don't need a bell housing you need a housing of a different shape on the rocket engine so with this thing you can get more thrust but im probab wrong im a business major
rbmaserang 2 years ago
My understanding is NASA has always had to compromise on nozzle shapes. Air pressure affects the efficiency of the design. Ideally a variable shaped nozzle would increase the efficiencies from sea level on up as air pressure decreases.
ewmegoolies 2 years ago
Yes, this type of nozzle shape would be more efficient in space over a regular bell nozzle. However, it is also more efficient while in our atmosphere as well, but the only problem is that the nozzle is surrounded by the hot exhaust, therefore actually getting one to work for say the space shuttle would be very very hard. NASA did look into this nozzle shape a long time ago and they have yet to figure out a way to use it, other than it being linear.
ragobgar 2 years ago
I cant quite make out what I am looking at here.. what the principle behind this design is meant to be..
drunk2thepowerofsick 2 years ago 2
Its a classroom demonstrator, so this video is just the hybrid running. But the idea behind it was to design a nozzle given the rocket parameters.
ragobgar 2 years ago
Would it be possible to email this from a personal email to a high school email address...I'm a high school teacher and my HS email won't allow me to access youtube. I would like to show this to my students.
kbboy11 2 years ago
download it.
lots of websites do this for free. google it.
LTKGuns 2 years ago
This might be too large to send by email, however there are a lot of programs you can find that can save any youtube video, in which you could then burn it onto a dvd to show in your classroom.
ragobgar 2 years ago
400 g's as in 882 pounds of thrust from that little thing??
ChesterDoraemon 2 years ago
grams hahaha
mrmanleedude 2 years ago
I assumed 400g to be grams not units of gravity. Could be wrong, wasn't explicitly relayed in the video.
ewmegoolies 2 years ago
I thought that I said that this produced thrust in units of grams...I'll have to go back and check and make that more clear. This is a very scalled down class demonstrator, so our professor and the school won't allow for anything larger than a few pounds of thrust.
ragobgar 2 years ago
hiiii
i am a graduate level student. i want to do my mazor project in aerospike nozzle .please share your experience with me.i have very less time...
lvgreat 2 years ago
Are you using propane for the ignition of the GOX-plexiglass fuel?
terriers2012 2 years ago
Yes, igniting the propane with a spark plug is easy, so once thats lit, we then transition to the gaseous oxygen (GOX).
ragobgar 2 years ago
Hey, very good video. I want to get into rocketry, and am probably going to design a hybrid rocket soon. I live near that school, and have heard about it a lot. Our schools robotic team is in the same competition as yours, our school is Samammish. It would be nice if I could come out and see one of your rockets in action.
scolen3 2 years ago
as in battlebot team?
hellkid94 2 years ago
The rocket club meets every saturday around noon, drive up to the baseball fields and walk to the hanger (its an actual aircraft hanger) and ask anyone where the rocket club (CPSS) is at.
ragobgar 2 years ago
COOL
boo880 2 years ago
Thanks.
ragobgar 2 years ago
this would really be efficient if a low temperature fuel would run thru the spike.
like in the cone of the nasa rocket engines.
but then again this is a smal scale.
good luck :]
aserta 2 years ago
Yep, exactly that, darn small scales...
ragobgar 2 years ago
What's the next step... sintered ceramic?
ANewNormalcy 2 years ago
I looked into ceramic's, so if I had more time I would have made one.
Thanks for the comment.
ragobgar 2 years ago
You okes clearly understand way more than me. Nice and interesting though, thanks!
5lick5ticker 2 years ago
what advantage would this have over a standard rocket motor?
avarlives 2 years ago
A standard rocket nozzle, the bell shape, is optimised to a particular altitude; in other words, the efficiency depends on the outside air pressure. This is bad, because as your rocket goes up through the atmosphere, the pressure drops, so the rocket gets less efficient. An aerospike engine is as efficient at ground level as in the upper atmosphere, so it takes less fuel to get into space, so your rocket can be smaller, so the payload for a given rocket can be bigger, and cheaper to launch.
thepsiborg 2 years ago 2
Well put.
ragobgar 2 years ago
How did you measure the thrust?
deeveezed 2 years ago
it pushed against a load cell that was connected to an old fashioned stripchart.
ragobgar 2 years ago
anyone taking an Aerospace career? I need to interview someone, really bad, please I love this field
SeedLover101 2 years ago
well i go to an aerospace highschool and i hope to work for nasa does that count ?
monimstarfox 2 years ago
highschool?! where? like academy or something
TopGunMan 2 years ago
nope the name is Aviation High school located in long island city queens search it on google :)
monimstarfox 2 years ago
Well, I would at Edwards AFB, but I'm pretty much in the testing aspect of a completed vehical, but its cool to see all them jet planes fly around.
ragobgar 2 years ago
nice looks fun to make
kazack66 2 years ago
It was a blast. Thanks.
ragobgar 2 years ago
i knew it would happen even before the testing.
eddimbr 3 years ago
Yeah, I had that feeling too, I just wish it still didn't happen... :( 30 hours machine time down the drain.
ragobgar 2 years ago
why the class cylinder befor the tear drop cone?
Vatherland 3 years ago
Thats so you can see the combustion, otherwise you would only see the fire coming out the end and not it swirling around inside. I don't think the videos give it justice as to seeing it in real life.
ragobgar 2 years ago
ME Department's Rocket dominates!
imbaratto 3 years ago
yeah maybe...but aeros test nozzles with fire (hot flow tests), not compressed air (cold flow tests). lol.
ragobgar 2 years ago
Clearly you are unaware of our full scale hybrid motor...LOL.
Kidding aside, our hybrid isn't an annular aerospike yet. Soon, the next phase I believe is a cooled spike annular aerospike hybrid motor. At the moment we have full scale cold flow aerospike and a cooled throat hybrid motor. Both on the order of 300 psi operating pressure.
imbaratto 2 years ago
Very interesting, If you had the time and money you could peak the efficiency and create very useful rockets
5/5
tombeeni 3 years ago
Thanks. I did do that a littlebit. But this one was just for my teacher, my real motor that I was building the school wouldn't let me fire it, after the Scaled Composite accident back in the summer of 07.
ragobgar 2 years ago
Did they ever conclusively determine what exactly caused the cold flow accident in Scaled composites? I suspect the N2O they used hit some catalytic metal like nickel and their composite fiberglass tank pressure got too high. I think they now realize it pays to have a burst disk on those things.
marmaladekamikaze 2 years ago
400 grams don't seem much for a rocket motor.
niiidar 3 years ago
Your right, 400 grams = ~ 1 pound... not very much at all, but this is just for demonstartion and I had too much to try to build and get working that I couldn't modifiy the components of the pre-existing rocket. I did build a 100 pound aerospike, but wasn't able to test it.
ragobgar 2 years ago
This comment has received too many negative votes show
Was that cum stain the first image?
Householdbreaker 3 years ago
i bet, i would love to do that kind of stuff
NiCKuhHFUCKER 3 years ago
its awesome how you guys fabricate your own shit
NiCKuhHFUCKER 3 years ago
Thanks, and it is a lot of fun too, unless you burn up your nozzle before its graded and have to remake another one...
ragobgar 3 years ago
sweet
NiCKuhHFUCKER 3 years ago
Thanks.
ragobgar 3 years ago
this is all awesome, i wish my uni had an aerospace program. i've never seen a transparent motor casing before, what pressure will it hold and could it burn through?
i was trying to research aerospike nozzles a few months ago but i googled up next to nothing.
i decided to make conventional conical nozzles from porcelain [after-hours artschool aerospace =D] and i'm nearly ready to test one, but i'd still be fascinated to see your drawings and get a handle on the design considerations!
iMAXIBON 3 years ago
Thanks for the comment. Well, this setup can only support about around 120-150 psi of O2 before the combution leakes out between the o-rings. It would be posible to have this be much greater, but that would require it to be redesigned.
As for finding information, if you can access AIAA, they have everything that I used. And if yor associated with a school, you should be able to have access to AIAA, at least it was when I looked through them a year ago.
ragobgar 3 years ago
Very nice video. I like the use of plexiglass (polycarb or acrylic?) for the combustion chamber.
I have a few questions:
1) After the ignition for a few seconds there is a squeal and the combustion regime is different. Is this because you are ramping your O2 up until you choke?
2) Ever consider using an inconel-series metal? Say 718? The stuff is a biznitch to machine though with the proper cutting tools you will get superior results.
3) What boundary conditions did you use on MOC?
doverdx 3 years ago
Thanks, glad you liked it. Yeah, thats why this uses the plexiglass as the comb. chamber so that it internal mixing can be viewed, although it makes it very bright. As for the instability, that is the propane dancing around, it probably has to do with not enough oxygen to burn since its not only burn itself but the plexi fuel aswell, ie very fuel rich. The oxygen is the bigger 'puff' in which its a pretty stable burn afterwards. As for the metal, I dont remember if I looked at that one or not.
ragobgar 3 years ago
And as for the BC, I'm not too entirely sure as to what they were, I wrote 2 programs, both of which were vastly different. The major program that was used for the tested design was purchased and I had no control over those parameters. Sorry I couldn't be more helpfull.
ragobgar 3 years ago
hey bro that was a nice video ,,,,am just wondering ,why don't you use titanium wouldn't be stronger , lighter ,and it can take so much heat before it melts ,,,take care
t0p0l1eve4 3 years ago
I looked into it, but from what I found, the temperature increase was only about 3-400 degrees C. So it would still have a hard time withstanding the temperature. As for its other qualities, this is a test nozzle, so the strengh and weight arnt very relavent to the testing. If I were to make this a flight test, then yes I would have looked into Ti a lot more. And it would have cost about 12-1500 dollars too, way to much for a senior project. But thanks for the suggestion.
ragobgar 3 years ago
What is an aerospike nozzle?
DTHRocket 3 years ago
Well an aerospike nozzle or aka a plug nozzle is pretty much an inverted rocket nozzle. A normal nozzle compresses the exhaust toward the center of the nozzle before expanding it back out again. The spike nozzle is more like a garden hose spray nozzle. Instead of defining the outer walls like the normal nozzle does, the spike nozzle only defines one wall and uses the atmoshpere as the other adjustable wall, therefore making it more efficient in terms of under or over expanding the flow.
ragobgar 3 years ago
Thanks
DTHRocket 3 years ago
Where I can found your senior project documentation ?? (Cal poly site ?).. I'm interessed in aerospike
fcanesin 3 years ago
Well, I'm not too sure if you would be able to access it from Cal Poly's web site, posibly. But I don't think I'll be submitting it anywhere else, like AIAA or anything. My report only has a few detailed drawings of the spike geometery, then its mostly concerning the results of my 3 test fires.
ragobgar 3 years ago
OK Thanks
What are equations to optimize the shape of the aerospike? is it possible to have the prog, or just the principle....
luc2408 3 years ago
Well, there are many books and websites devoted to the Method of Characteristics that you can look at if you really wanted to get lost in all the math to understand how it works. As for giving away my program, its not that user friendly and would probably be hard to understand, I know that I don't even understand how it all works.
ragobgar 3 years ago
Hi,
I would like to know what model are you using to determinate the shape of the nozzle. And what is your combustion model.
Thanks do not hesitate to contact me or send me information.
Regards Luc
Good work
luc2408 3 years ago
Well, I wrote two computer programs to design the shape, one using simple geometry and the other using method of characteristics. I also purchased a design program from AeroRocket Technology which also uses method of characteristics. I used each program to design nozzles that were tested in cold flow tests befor designing the hot flow nozzle. As for a combustion model, I did not perform any CFD analysis. If I had I could have submitted this for a Masters Thesis instead of just a Bachlors. :)
ragobgar 3 years ago
Great vid and excellent rocket, thanks!
lepermunna 3 years ago
Is it plexiglass tube burning or propane and oxygen ?
666kiki666 3 years ago
The propane is only used to ignite the oxygen, it may also react with the plexiglas fuel grain but only very little. Once the propanes burn is at steady state, the pulsating in the first attempt, then the oxygen is injected and the propane is turned off. The propane provides a hotter flame to ignite the oxygen than the spark plug that ignites the propane. The Oxygen then burns with the plexiglas. Thanks for the comment.
ragobgar 3 years ago
Try streamlining those spokes. gas friction at that speed makes even more heat. the more streamlined, the better for less resistance to the flow. also it might make it more powerful by cleaning up the flow stream
alexsydmaddie 3 years ago
Yeah, thats pretty much what happened, and thats what the second nozzle was designed for. The three holes were more streamlined than the 'wagon spokes' which caused stagnation areas in the flow, heatting it up beyond the normal exhaust temperatures. Thanks for the advise.
ragobgar 3 years ago
good job doug. similar concept to the aerospike nozzle i machined 2006. just presented it at the 2008 AIAA student conference and took first. my close friends and i are working on the new ones now. keep up the good work.
doc34thumper 3 years ago
Cool, thanks. Yeah, that was my small nozzle, my school wouldn't let me use NOS which I had for my larger, ~100 lbf aerospike. I have it all machined up, just need NOS to fire it off.
ragobgar 3 years ago
yeah... when i did mine, it was already a personal project and found out i could turn it into a independent study at the university. so, i had already purchased all the equipment. they did though offer supplies when i signed up for the independent study. why wont they let you use N2O ?????
doc34thumper 3 years ago
The school isn't allowing us to use NOS because of what happened to Scaled Composites last summer, where there NOS tank blow up