This guy is so smart and self-deprecating, I will not be surprised when 2.0 special effects package butane afterburner puts out at least notable thrust. I mean it's not rocket science, oh wait..
Building that thing and then burning it down with an "effect" seems, umm, odd...at least generate thrust... The t-flight guys I think did this with thrust...
Just my 2 cents: 1) run a coil of copper tube in the exhaust before combusting the butane. It’ll vaporise it and give you less fuel consumption and a cleaner burn. 2) keep the low pressure zone you’ve got the same, but make sure you have some air inlet holes at the top as you need the fuel to combust in the zone which will require airflow. If the hole’s too big it’ll blow it out. 3) look at David Windestal, he made one for edf. Seemed to work quite well.
Or ... simply turn the can and mount upside down and use what's already available. As a side note I also wanted to add that his mentioning of "lighter fluid" is way different than butane or even liquid butane, it's more like kerosene.
Richard Duncan Even Elon marvelled at the Mach diamonds on his Raptors, I highly doubt anyone is creating a mini engine with Mach diamonds... no, I’m certain of it, lol
Yep as some other people have mentioned, check out the Flite Test video about EDF afterburner, the way they made the burn cleaner is by running the butane through a heating coil inside the flame to aerosolize it before releasing and igniting it so that there’s no wasted butane and the burn is more even and quicker. Also that way you don’t need any extra power for the heating, since the flame is doing it for you. The only hard part there is the ignition but I think it’s worth it.
He figured anymore fire in this video would call too much attention to his inner pyro, so the shirt was hope to tone it down a bit. Otherwise this video would be lit.
Respect gained dude. Its very respectable what you do with mostly simple hobby equipment. Its the next plausible step in model rocketry. Just most of us never got this far. Well done sir.
Was just going to comment, it looks just like it! He might also want to try adding a brass coil heated tube on the fuel inlet line to help with turning the liquid butane into a gaseous state quicker. That's what Peter Stripol did on the Flitetest episode when it was very cold out. EDIT: woops hadn't finished the video, looks like he's already running the butane through a tube around the flame to heat the butane!
Couple of observations that may or may not help. 1. Butane will remain in liquid state at just below zero. (Celcius) We have had clients with this issue with burners. As the butane evaporates, it cools the system and adds to the problem. (Propane continues to evaporate at much lower temperatures). 2. Your exhaust external environment is effectively static, afterburners generally operate with turbulent fast moving (relative) atmosphere. (better mixing of air and fuel after leaving ignition zone) This can be seen with blue flame where fan air is mixing and orange flame beyond. Less fuel may be better. A Venturi, or simple air entrainment opening prior to the burner, will help a lot. Heating the fuel will help. Direct the cold fuel to a lower coil (that gets more heat) then run it back up to the release point. Study "bluff bodies" and see if you can provide somewhere for the flame to "sit" on. This way you will gain a lot more control over it. Hope some of that helps a bit, and keep it up 👍
Love what you are doing, I told my son how cool will it be when someone actually makes a real working rocket engine. His reply was it’s to complicated, mine was you have guys in home shops making turbines.
Add fuel in levels below the flammability limit into the intake and just add extra at the after burner stage to get it over the line, that way you've already got a good homogenization to aid with flame stability and get a jet like flame
I am 70 years old and only understand about 2% of what you say! But that’s the power of RUclips I still watch every stream you put out and love to hear you try and explain what it is you are doing! Oh and I think the “flame” bits are great to.
Not sure if I remember correctly from my RC jet engine days but I see three problems: 1. The fan creates a vortex which will spread out the flame so those "anti-torque vanes" need to be present after the fan as well. 2. As you mentioned, you will need a flame holder for that afterburner. 3. This is useless, but fun and cool. :)
Those flames look really cool! I would suggest that adding the afterburner will in fact decrease the thrust produced by the EDF, as that is what I have experienced with my own tests (which you can see on my channel). This is because the combustion creates a region of high pressure behind the EDF, reducing the air flow.
The stators will also be stagnating the flow off the back of the fan, which also recovers pressure from tangential velocity, increasing the thrust you get from the fan.
0:55 when you build a hyper complex fan powered hopper with afterburner and dual band GPS, just to clip your mic to it EDIT: Just use some gaffer and some parts from RIPed mic stands like everyone of us sound engineers do. And don't forget to NEVER EVER match the mic brand to the brand written on the mic clip
Joe, something you might want to check is the nozzle size and angle. I like to model steam engines but hate the smell and mess of coal. I switched to using propane in my models but I found that different manufacturer of camping stoves, I uses as parts, nozzles vary quite a bit in hole diameter and concentrate. For my uses, I purchase under sized nozzles and dial it in using a four jaw chuck then re drill with precision drills. This gave me a better spray pattern.
If you check out "Tech Ingrediens" here on RUclips, They actually use the EDF as a pre-compression stage for their jet engine in a true hybrid electric/gas jet engine. In their case both components contribute greatly to the thrust of the engine.
MrRolnicek, I’m familiar with their work. It’s really cool but the amount of support hardware to make that function wouldn’t really be practical for this application, IMO. Tech Ingredients were trying to achieve usable thrust from the fuel, but Joe is just trying to achieve some visual effects. I get what you’re saying but two different applications.
@@anthonydomanico8274 You can still use it as a reference to learn valuable lessons. Also a lot if not most of that hardware is for prototyping, they're perfectionists so they want to make it the best they can. For that they need to be able to tweak as many parameters as possible during operation. All I'm saying is, he's burning fuel anyway so why not get some thrust out of it while he's at it?
Hey, good work. On thrust: Yes you can create thrust with a burner in an EDF, but I am pretty sure you need to enclose the section where the fuel is being burned, otherwise the gas will expand everywhere and not actually accelerate. Have a look at the channel "Tech incredients", he built a EDF with a burner and doubled his thrust I believe! (even tho he used two EDF in series, little bit different setup than you)
The close-up view seems to indicate that the fuel is not vaporizing fast enough to get a complete burn, possibly the use of a servo'd valve could give you more control. Also, creating a vortex in that upper section may help as well... awesome stuff, keep it happening :)
BPS.space: Instead of building a complicated setup yourself and trying to debug it, you could use the business end of a soldering lamp. This also usually comes with a build in regulator as well as ignition wires.
First a question followed by some ideas I have regarding the low pressure zone issue mention around 4:30 I think. My question is, why would the afterburner limit your thrust? Unless you only meant that you couldn't sustain the afterburner at higher thrust levels. Now for the afterburner ideas (all 4 points are good info on flame holders, but later I realized they are irrelevant. skip to the edit at the end for the actual recommendation): 1) Regarding the flame favoring one side rather than being even, I suspect this is due to the flame holder design. It appears as if this is a truncated cone which I suspect causes the issue of the flame shooting off to one side. My guess is that flow along the inside of the cone is separating in the same way that flow separates from the top surface (ie the low pressure surface) of a wing when it hits its stall angle. However, once it has separated from one side, all of it sticks to another side. In an ideal world with perfect manufacturing and uniform flows it would separate evenly along the entire edge, but life is rarely ideal. (possibly incorrect, see edit at end), 2) The easiest solution to 1 would be to complete the cone and not allow air to enter the interior of the cone and eliminate the idea of flow separation as an issue by eliminating the interior flow. However this obviously worsens the thrust losses, but its on the right track and is roughly the idea behind most flame holders in actual afterburners. 3) A more thrust friendly solution would be to convert your truncated cone into a V-gutter flame holder. Here's an image (sorry for the potato quality) of one, you've likely already seen this kind a million times before: farm5.staticflickr.com/4867/31969345377_4cfc3793b0_n.jpg 4) Not sure how much you've already read up on the topic bet if you'll indulge me I'd like to delve into the theory behind gutter style flame holders. Imagine you have a pitot tube facing into the flow; air enters the tube and comes to a halt, thus measuring the total pressure (or stagnation pressure) of the flow as you'd expect. Now point the tube at a right angle to the flow; air in the tube is sucked out until the pressure in the tube is equal the to static pressure of the flow, again as you'd expect. Now point the tube backwards so that it faces downstream and you would find that the pressure in the tube is slightly _lower_ than the static pressure of the flow. This is because now you are measuring the static pressure minus whatever eddies and vortices the tube is leaving in its own wake. The the gutter of a gutter style flame holder is effectively like that backwards facing pitot tube. Now I'm assuming you are imaging a pitot tube as it appears in this image (ie with that 90 degree bend): i1.wp.com/automationforum.co/wp-content/uploads/2018/01/ptot.png?resize=580%2C375&ssl=1 Well imagine you have that backwards pitot tube and you poke a small hole in the back of the tube so that it allows a tiny amount of the oncoming air to leak into the tube. The pressure would still be lower than the static pressure, but less so than without the hole. When you truncated the cone of your flame holder, you effectively poked a gigantic hole in your backwards facing pitot tube. Edit: From the camera angle looking down into the EDF I see that, while still being a truncated cone, the center of the cone does not appear to be ingesting airflow so it should have indeed acted like a gutter style flame holder. I now have a better theory as to why the flame holder didn't work. Since the stators are canted at a fixed angle, in theory there is only one thrust level where they perfectly cancel out the vorticity. In fact I would bet that just those 4 stators aren't enough to ever fully cancel out the vorticity, but even if they are my main point is still relevant: the flow likely had a lot of vorticity. So the incoming flow might actually have had a lower static pressure than the region inside the flame holder. However, this is good news. The lowest pressure of a vortex is always at the center of the vortex. So it would likely perform much better if you _removed_ the flame holder entirely. Of course, when you reach the thrust level where vorticity is perfectly canceled this would abruptly blow out the flame, but as I state before I _highly_ doubt that those stators would ever be enough to completely cancel the vorticity, but that's just a guess. Alternatively, if you still prefer a flame holder model, you could try to add long straight stators to the EDF outlet duct (or lengthen the duct to add them after the existing canted stators). I'd use long straight stators rather than canted ones because canted ones only work at a fixed thrust setting while straight ones work for all thrust settings but need a longer chord length to work well.
Hey man. The reason your afterburner flame is moving erratically is because the flow in the nozzle is detaching from the nozzle wall. The reason this is happening is because you’re passing subsonic flow through a divergent nozzle (doing this will also decrease the efficiency of your EDF). Divergent nozzles are designed for supersonic flows. I’d recommend either using a straight nozzle (a tube) or a slightly convergent nozzle. I don’t think this problem is because of flow obstructions or bad fuel mixing. Good luck!
You can build an electric turbo compresor so you can inject like 1 psi of air more to that after burner, i think it can help whit getting a better mix with that fuel and probably get real trust from that combustion 🤔😁 (please give a heart or comment what do you think so I now if you've read the commentary xD)
Weird question but when you speak about working on your aircraft you always say “we”. Love your work just wondering if you work with yourself or with someone. Edit: this is a serious question. I presume he says "we" because people also help in the community and also like someone said in science reports they never say 'I'.
If the fuel is burnt inside the same duct from the EDF, you might actually get some thrust from that afterburner. But it would require some tests to determine if the resistance created by the additional duct and fuel injection stuff can actually be compensated by the thrust addition.
I've got a Hubsan 501s-s drone which uses the ground effect lights as part of the compass calibration and various diagnostic features of firmware upgrade successes. Interesting approach anyways and certainly has no problem getting off the ground or descending with enormous velocity while stable and in a sound landing solution.
Put a throat after the fan? It'll create a low pressure zone. Another idea to circumvent the liquid butane problem: instead of feeding the fuel thru a small tubing, you could attach a secondary duct that sucks (using the EDF pressure) aerosol + air and dumps into after the fan. Explore the fact that the expanding gas leaves with momentum and will help to create a low pressure to suck the air near the canister outlet.
Are are liquid rocket injector designs floating around on NASA documentation. That may help atomize the butane very well for combustion. You can mill those injectors but you proper have to tweak the designs for the flow rate and “mol rate” for the most complete burn with oxygen.
Super cool that you got this far!! So just that I get this straight, that this is kinda more like a mini jet engine rather than rocket engine cuz no carried O2...
Your mandatory obligation is to get this machine flying in the next 6 months before FAA drops the hammer and turns every rc craft into mantel ornaments. Superb work ! exquisite complexity at its finest.
The flame isn't igniting in the engine bell. If you do want to sustain it, you are going to need to have a viable control on the butane flow. If the butane can't sustain a flame at anywhere above 40%, you're going to need a tank for the butane that will allow for a higher feed rate.
It's just a gas burner. You need a divergent nozzle so the expanding gases drop the pressure after the turbine so it's pulling in more air. All you're doing there is using your jet exhaust gas to light a flame. When you get it right your fuel consumption will go up exponentially.
Good job so far! Following closely. A couple of suggestions: You might want to look into nitrous jets used in racing, there's a decent range of sizes to experiment with quickly, and you could put them inline with the tubing. Regulating close to the bottle would slow down the butane flow enough for it to stay in the copper tubing longer to gather heat, and give it some room to expand into gaseous state. Also you may want to extend the nozzle so there's more room (and time) for the heat exchanging process without having to block any airflow from the EDF. You also might have to find a way to put it on a little bit of a diet, or double up on the EDFs (which could help solve the torque problem if they counter-rotate).
On that spiral tube where you heat the butane. Have the last spiral have a few holes evenly spaced in it, and block the end of the tube. This way butane is coming out in multiple places in the combustion chamber. It should make the flame more even.
30 year pilot (and RC pilot) here (non-engineering BA!) but, I am concerned about the butane combustion chamber interfering with a smooth flow out of the fan unit. While you are machining the new vanes, why not have a slim teardrop butane emitter made with like 1/20th the size of the speed taped unit? The fan air needs as few interruptions as possible to be efficient. A tiny nozzle the size of a pencil eraser with a 1/2-1" spike above it would propagate flame well while offering minimal fan inefficiencies due to turbulence. You just need to see a nice flame under the Sprite in flight. Awesome work! Good luck in your flight test phase.
I appreciate the added thrust😂😂 But seriously trying dumping some NO2, or just straight O2 through the stators before it hits the butane for some extra kick.
Looks like your butane is forming fairly large droplets - a finer spray will burn more quickly and stably, hopefully avoiding being blown out. Basically you need finer spray nozzles or possibly inject the butane farther upstream - even before the EDF blades maybe, so they break up the droplets.
If you wanted a noticeable increase in thrust, wouldn't you need more of a nozzle? The gas is just expanding in every direction. I realize you know this, but just curious what the plan is if you actually do try and measure it on the stand.
Something you may wish to consider as ignition of combustables and save a bunch of weight are USB Lighters. they produce about a 7mm constant arc. come with their own batteries and USB chargeable.
With the butane afterburner, why not have the can in the upright position, that way it sends more gas than liquid. I would also recommend some sort of spray nozzle to give a better flame.
Propane would likely work better for producing usable thrust, it's much lower boiling point is a major plus when using ambient temperature to pressurize the tank.
Joe, what is your real object? To get the hopper flight control system working, or watch a flame? Unless you are going to make a hybrid jet engine with the EDF and a compression/burner section, you might want to pick one or the other. Also, on those vector fins, aluminum may not be the best material as it will distort from the heat over time. Try making them from ceramic like a thin tile and cut as needed from a big box store.
Cool video! "Butane fumes" should only be CO2 and H2O, nothing to worry about with the door open as you did! Hum... Combustion is not perfect, flames are yellow, you have CO as well. Ventilate!
What if you had two EDFs, layered with the lower pitch blades above, forcing air down into a higher pitch EDF, so neither would be working as hard as they otherwise would, and the higher pitch EDF receives more cooling? Keep up the great work, you’re awesome.
Are you just injecting the butane with a single nozzle? Perhaps after the preheat turns a full circular nozzle with small holes would be better for injecting into the afterburner? By that I mean that the nozzle has an input after the preheat and then into a full ring of copper pipe (or whatever material it is) and the only ouput for the butane is the small holes.
Hey Joe, I love your channel. I think the flame issue is primarily from asymmetric fuel distribution. I’m curious, why do you want the butane oriented upside down? Are you trying to more closely approximate a liquid fueled engine? I have no doubt you already know that symmetric distribution and ignition is much easier to achieve with a gaseous fuel. Not criticizing, just trying to better understand the goal. Thanks!
Interesting approach: A couple of ideas. . ? 1)What about an inverse "Plugged Nozzle" at front of the firebox? 2) Concrete Patch, or Fireplace cement is an excellent fire shield which can be easily shaped and formed when dry.
Kit; A while ago, I seen someone using 'Instant Patch to make complete nozzles with. He had a mold milled out of aluminum in the shape of the inner bell with a throat extension, that he sat centered, at the bottom of a tube, then poured the mixture over it. A consistent engine nozzle every time. Nowadays, a simple 3D printer could do that mold quick and easily. Any modification desired would be greatly sped up, and the cost of the "milling" would be reduced to only some mono filament and the time required to burn it. Just a fun thought.
David Windestal made an edf after burner for an rc jet years ago, his video should still be on the flitetest page or his but he did manage to get it working. It may be worth taking a look at his successes, and failures.
"What is this? Some kind of plastic ice-cream scoop?" -Harry Stamper *THUD* It's cool that super-heating your propellant is trivial to someone inclined at this scale. Vat vas dat? fthrust chamba instabiliti? auhhahauha...
"It's better to look good than to feel good, darling." - Fernando SNL You are so right, Joe. Sometimes the cool factor just wins out over practicality. I am ashamed to say I have also flown some sketchy aircraft in sketchy conditions only for the hope and gamble of some great usable video. Keep up the cool factor... :)
I'm glad you clarified th point of the afterburner at the start of the show 👌 I'm wondering if the heat of the flame will have a negative effect on the performance of the lift fan. Lower density air and such.
I'd look for areas where you can 'add lightness,' to borrow a phrase. For instance, those huge, metal toggle switches on the side could be replaced by something far lighter (albeit, less cool looking). Can you maintain structural integrity on the grey (printed?) parts with less material? Do your fasteners all have to be so chunky? (Those big, pan-head screws...) Have you optimized your wiring to reduce as much extra as possible? (Copper is super heavy!) Could you get by with less zip ties? (Every extra gram helps.) These are just off the top of my head. It gets easy to become locked into a design, and it gets harder and harder to know when to call it good with optimizations, but there seems to be quite a bit left on the table here still. Anyways, thanks again for the vid and good luck!
Fire for effect! Brilliant! Could you add intake vents that double as descent/landing flaps that are higher than the butane ignition point? This may allow for additional air without eliminating the low-pressure zone you’re talking about? It may also reduce your overall weight enough to break the balance.
You could probably use a fuel injector of some sort on that thing; I think it would make your butane drip less and be more of a mist, which would not only burn better but it might even burn more evenly.
I'm assuming this was inspired by a certain Flite Test video, is there any reason why the circular tube they used with their butane afterburner is replaced with the nozzle?
you could probably put a smaller venturi in the center of the EDF outlet flow path and have a small nozzle (or multiple) that help siphon the butane out. Basically a carburetor. I'm not sure how well it would work with butane, but it's worth a shot and you might actually be able to get better A/F ratios and a little thrust. Maybe even cutting the venturi out of an existing carb and getting a jet kit for it to adjust the nozzle diameter. My explanation is a bit weird and not the best way to describe how carbs work, but I wanted to be a bit more clear on how they work in case you weren't familiar
*Seeing the ignition test
"Sweet, I wonder how much extra thrust it prov-"
"It's mostly just for looks..."
"Oh."
This guy is so smart and self-deprecating, I will not be surprised when 2.0 special effects package butane afterburner puts out at least notable thrust. I mean it's not rocket science, oh wait..
A bit like the old batmobile.
Building that thing and then burning it down with an "effect" seems, umm, odd...at least generate thrust... The t-flight guys I think did this with thrust...
Notification squad! Excited to see what the heck this thing is 😱
Everyday Astronaut
That whole intro was so star wars‘y
I think we will need an hour plus long video from you to figure out what it is 😉
Everyday Astronaut you 2 should make a series together about building a mini model liquid fueled rocket
ohh man u r awesome , you are the best spaceoholic i ever seen
Wow my other fav youtuder
LOL the sponsor bit, I was like oh god no not raid shadow legends, brilliant, or skillshare.
or honey
I was worried it was Nord VPN
OMG LOL
Legit thought he landed a soft drink sponsorship. 😝
Haha you just confirmed those adds actually work.
Just my 2 cents:
1) run a coil of copper tube in the exhaust before combusting the butane. It’ll vaporise it and give you less fuel consumption and a cleaner burn.
2) keep the low pressure zone you’ve got the same, but make sure you have some air inlet holes at the top as you need the fuel to combust in the zone which will require airflow. If the hole’s too big it’ll blow it out.
3) look at David Windestal, he made one for edf. Seemed to work quite well.
Or ... simply turn the can and mount upside down and use what's already available. As a side note I also wanted to add that his mentioning of "lighter fluid" is way different than butane or even liquid butane, it's more like kerosene.
no matter what your level of professionalism or education we ALL love to see some controlled exothermic reactions! Love me some blue diamonds.
0% chance of him producing Mach diamonds on this version of the aircraft, sorry
Richard Duncan Even Elon marvelled at the Mach diamonds on his Raptors, I highly doubt anyone is creating a mini engine with Mach diamonds... no, I’m certain of it, lol
@@zoidburg2975 Glad you've come around to see my original position lol
Yep as some other people have mentioned, check out the Flite Test video about EDF afterburner, the way they made the burn cleaner is by running the butane through a heating coil inside the flame to aerosolize it before releasing and igniting it so that there’s no wasted butane and the burn is more even and quicker. Also that way you don’t need any extra power for the heating, since the flame is doing it for you. The only hard part there is the ignition but I think it’s worth it.
My respect for you as an engineer has actually increased because you admitted that the afterburner is just for looks
4:29- nonononononono you just need MOAR BOOSTERS
MOAR STRUTS
@@andrewgarberXYZ MOAR everything!!!!!!!!!
Haha I'm literally playing KSP while watching this video
Profilepicture checks out
It's more* you idiot.
"I really love fire" says the guy with flowers and doves on his shirt
He figured anymore fire in this video would call too much attention to his inner pyro, so the shirt was hope to tone it down a bit. Otherwise this video would be lit.
I love the old style of very refined videos, but this is better, you seem well less stressed and at ease, keep it up !
Respect gained dude. Its very respectable what you do with mostly simple hobby equipment. Its the next plausible step in model rocketry. Just most of us never got this far. Well done sir.
Looks amazing. Would recommend the flite test video on a afterburner similar to this
Was just going to comment, it looks just like it! He might also want to try adding a brass coil heated tube on the fuel inlet line to help with turning the liquid butane into a gaseous state quicker. That's what Peter Stripol did on the Flitetest episode when it was very cold out.
EDIT: woops hadn't finished the video, looks like he's already running the butane through a tube around the flame to heat the butane!
2:37 every kid on xbox 360 with a walmart mic
Edit: Okay... Didn't expect so many people to like my comment. Thank you guys!
LOL
Ah.... the internet never stops on amusing me! Well done sir, you made my day!
Frikin Normies, REEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE
I don't know if you win the internet, but you win my like
That is true
Hope you keep it up with these interesting presentations and explanations of what you are doing.
Beautiful! To me, it's a great business decision. More flame = more eyeballs = more project support.
Couple of observations that may or may not help.
1. Butane will remain in liquid state at just below zero. (Celcius) We have had clients with this issue with burners. As the butane evaporates, it cools the system and adds to the problem. (Propane continues to evaporate at much lower temperatures).
2. Your exhaust external environment is effectively static, afterburners generally operate with turbulent fast moving (relative) atmosphere. (better mixing of air and fuel after leaving ignition zone)
This can be seen with blue flame where fan air is mixing and orange flame beyond. Less fuel may be better.
A Venturi, or simple air entrainment opening prior to the burner, will help a lot.
Heating the fuel will help. Direct the cold fuel to a lower coil (that gets more heat) then run it back up to the release point.
Study "bluff bodies" and see if you can provide somewhere for the flame to "sit" on. This way you will gain a lot more control over it.
Hope some of that helps a bit, and keep it up 👍
Keep it up BPS! Love your stuff and the level of documentation you go through.
-A real fan.
Love what you are doing, I told my son how cool will it be when someone actually makes a real working rocket engine. His reply was it’s to complicated, mine was you have guys in home shops making turbines.
Bravo on the environment set-up, it looks super esthetic with all the led lights in it! the video is also crisp.
Add fuel in levels below the flammability limit into the intake and just add extra at the after burner stage to get it over the line, that way you've already got a good homogenization to aid with flame stability and get a jet like flame
I am 70 years old and only understand about 2% of what you say! But that’s the power of RUclips I still watch every stream you put out and love to hear you try and explain what it is you are doing! Oh and I think the “flame” bits are great to.
Not sure if I remember correctly from my RC jet engine days but I see three problems:
1. The fan creates a vortex which will spread out the flame so those "anti-torque vanes" need to be present after the fan as well.
2. As you mentioned, you will need a flame holder for that afterburner.
3. This is useless, but fun and cool. :)
Those flames look really cool! I would suggest that adding the afterburner will in fact decrease the thrust produced by the EDF, as that is what I have experienced with my own tests (which you can see on my channel). This is because the combustion creates a region of high pressure behind the EDF, reducing the air flow.
The stators will also be stagnating the flow off the back of the fan, which also recovers pressure from tangential velocity, increasing the thrust you get from the fan.
0:55 when you build a hyper complex fan powered hopper with afterburner and dual band GPS, just to clip your mic to it
EDIT: Just use some gaffer and some parts from RIPed mic stands like everyone of us sound engineers do. And don't forget to NEVER EVER match the mic brand to the brand written on the mic clip
I have been looking around RUclips and there are lots of rocketry channels that all say they are inspired by you. You have really started something
I just discovered your channel after watching what sprite is
Watch his Thoomp Episode...
you convinced me to apply for phd studies. love from morocco
feen a sat
deja khadam db mais bari narja3 I like the stuff. Enset rabat yamkan wla ensa kenitra
Joe, something you might want to check is the nozzle size and angle. I like to model steam engines but hate the smell and mess of coal. I switched to using propane in my models but I found that different manufacturer of camping stoves, I uses as parts, nozzles vary quite a bit in hole diameter and concentrate. For my uses, I purchase under sized nozzles and dial it in using a four jaw chuck then re drill with precision drills. This gave me a better spray pattern.
You are one of the most if not the most entertaining youtuber out there - even if you would talk about boring stuff you would make it sound awesome ;)
If you check out "Tech Ingrediens" here on RUclips,
They actually use the EDF as a pre-compression stage for their jet engine in a true hybrid electric/gas jet engine.
In their case both components contribute greatly to the thrust of the engine.
MrRolnicek, I’m familiar with their work. It’s really cool but the amount of support hardware to make that function wouldn’t really be practical for this application, IMO. Tech Ingredients were trying to achieve usable thrust from the fuel, but Joe is just trying to achieve some visual effects. I get what you’re saying but two different applications.
@@anthonydomanico8274 You can still use it as a reference to learn valuable lessons.
Also a lot if not most of that hardware is for prototyping, they're perfectionists so they want to make it the best they can. For that they need to be able to tweak as many parameters as possible during operation.
All I'm saying is, he's burning fuel anyway so why not get some thrust out of it while he's at it?
Hey, good work. On thrust: Yes you can create thrust with a burner in an EDF, but I am pretty sure you need to enclose the section where the fuel is being burned, otherwise the gas will expand everywhere and not actually accelerate. Have a look at the channel "Tech incredients", he built a EDF with a burner and doubled his thrust I believe! (even tho he used two EDF in series, little bit different setup than you)
I second the Tech Ingredients recommendation. That video is extremely informative, as is the rest of his channel.
@@jamesburleson1916 Yes!
The close-up view seems to indicate that the fuel is not vaporizing fast enough to get a complete burn, possibly the use of a servo'd valve could give you more control. Also, creating a vortex in that upper section may help as well... awesome stuff, keep it happening :)
Damn, even if its just for looks, that’s AWESOME!!! Can’t wait to see what sprite turns into.
BPS.space: Instead of building a complicated setup yourself and trying to debug it, you could use the business end of a soldering lamp. This also usually comes with a build in regulator as well as ignition wires.
How soon until competitors show up and demonstrate their builds of 7-up, Ginger Ale, and Mt. Dew?
What about Aerospace Doctorate Pepper?
First a question followed by some ideas I have regarding the low pressure zone issue mention around 4:30 I think. My question is, why would the afterburner limit your thrust? Unless you only meant that you couldn't sustain the afterburner at higher thrust levels. Now for the afterburner ideas (all 4 points are good info on flame holders, but later I realized they are irrelevant. skip to the edit at the end for the actual recommendation):
1) Regarding the flame favoring one side rather than being even, I suspect this is due to the flame holder design. It appears as if this is a truncated cone which I suspect causes the issue of the flame shooting off to one side. My guess is that flow along the inside of the cone is separating in the same way that flow separates from the top surface (ie the low pressure surface) of a wing when it hits its stall angle. However, once it has separated from one side, all of it sticks to another side. In an ideal world with perfect manufacturing and uniform flows it would separate evenly along the entire edge, but life is rarely ideal. (possibly incorrect, see edit at end),
2) The easiest solution to 1 would be to complete the cone and not allow air to enter the interior of the cone and eliminate the idea of flow separation as an issue by eliminating the interior flow. However this obviously worsens the thrust losses, but its on the right track and is roughly the idea behind most flame holders in actual afterburners.
3) A more thrust friendly solution would be to convert your truncated cone into a V-gutter flame holder. Here's an image (sorry for the potato quality) of one, you've likely already seen this kind a million times before:
farm5.staticflickr.com/4867/31969345377_4cfc3793b0_n.jpg
4) Not sure how much you've already read up on the topic bet if you'll indulge me I'd like to delve into the theory behind gutter style flame holders. Imagine you have a pitot tube facing into the flow; air enters the tube and comes to a halt, thus measuring the total pressure (or stagnation pressure) of the flow as you'd expect. Now point the tube at a right angle to the flow; air in the tube is sucked out until the pressure in the tube is equal the to static pressure of the flow, again as you'd expect. Now point the tube backwards so that it faces downstream and you would find that the pressure in the tube is slightly _lower_ than the static pressure of the flow. This is because now you are measuring the static pressure minus whatever eddies and vortices the tube is leaving in its own wake. The the gutter of a gutter style flame holder is effectively like that backwards facing pitot tube. Now I'm assuming you are imaging a pitot tube as it appears in this image (ie with that 90 degree bend):
i1.wp.com/automationforum.co/wp-content/uploads/2018/01/ptot.png?resize=580%2C375&ssl=1
Well imagine you have that backwards pitot tube and you poke a small hole in the back of the tube so that it allows a tiny amount of the oncoming air to leak into the tube. The pressure would still be lower than the static pressure, but less so than without the hole. When you truncated the cone of your flame holder, you effectively poked a gigantic hole in your backwards facing pitot tube.
Edit: From the camera angle looking down into the EDF I see that, while still being a truncated cone, the center of the cone does not appear to be ingesting airflow so it should have indeed acted like a gutter style flame holder. I now have a better theory as to why the flame holder didn't work. Since the stators are canted at a fixed angle, in theory there is only one thrust level where they perfectly cancel out the vorticity. In fact I would bet that just those 4 stators aren't enough to ever fully cancel out the vorticity, but even if they are my main point is still relevant: the flow likely had a lot of vorticity. So the incoming flow might actually have had a lower static pressure than the region inside the flame holder. However, this is good news. The lowest pressure of a vortex is always at the center of the vortex. So it would likely perform much better if you _removed_ the flame holder entirely. Of course, when you reach the thrust level where vorticity is perfectly canceled this would abruptly blow out the flame, but as I state before I _highly_ doubt that those stators would ever be enough to completely cancel the vorticity, but that's just a guess. Alternatively, if you still prefer a flame holder model, you could try to add long straight stators to the EDF outlet duct (or lengthen the duct to add them after the existing canted stators). I'd use long straight stators rather than canted ones because canted ones only work at a fixed thrust setting while straight ones work for all thrust settings but need a longer chord length to work well.
Hey man. The reason your afterburner flame is moving erratically is because the flow in the nozzle is detaching from the nozzle wall. The reason this is happening is because you’re passing subsonic flow through a divergent nozzle (doing this will also decrease the efficiency of your EDF). Divergent nozzles are designed for supersonic flows. I’d recommend either using a straight nozzle (a tube) or a slightly convergent nozzle. I don’t think this problem is because of flow obstructions or bad fuel mixing. Good luck!
You can build an electric turbo compresor so you can inject like 1 psi of air more to that after burner, i think it can help whit getting a better mix with that fuel and probably get real trust from that combustion 🤔😁 (please give a heart or comment what do you think so I now if you've read the commentary xD)
Or even better, a turbo rocket using the miniature electric turbo compressor. Using atmospheric air as the oxidised in a rocket
Weird question but when you speak about working on your aircraft you always say “we”.
Love your work just wondering if you work with yourself or with someone.
Edit: this is a serious question. I presume he says "we" because people also help in the community and also like someone said in science reports they never say 'I'.
he is alone
Doh, ...hamster in his pocket.
I like to think he's including us! But, maybe it's the "royal we". Or, maybe he really cares about his project and can't resist anthropomorphizing.
All human achievement is collaborative. ✊🤓💜
I think it's the scientific "we". In science papers with only one author you see it a lot.
If the fuel is burnt inside the same duct from the EDF, you might actually get some thrust from that afterburner.
But it would require some tests to determine if the resistance created by the additional duct and fuel injection stuff can actually be compensated by the thrust addition.
I've got a Hubsan 501s-s drone which uses the ground effect lights as part of the compass calibration and various diagnostic features of firmware upgrade successes. Interesting approach anyways and certainly has no problem getting off the ground or descending with enormous velocity while stable and in a sound landing solution.
Sounds awesome. If you added a constricting tube on the end you could probably squeeze some thrust out of it
Put a throat after the fan? It'll create a low pressure zone.
Another idea to circumvent the liquid butane problem: instead of feeding the fuel thru a small tubing, you could attach a secondary duct that sucks (using the EDF pressure) aerosol + air and dumps into after the fan. Explore the fact that the expanding gas leaves with momentum and will help to create a low pressure to suck the air near the canister outlet.
Watching an hour long ad excited to see the video! happy fresh rotation around the sun!
Are are liquid rocket injector designs floating around on NASA documentation. That may help atomize the butane very well for combustion. You can mill those injectors but you proper have to tweak the designs for the flow rate and “mol rate” for the most complete burn with oxygen.
Super cool that you got this far!! So just that I get this straight, that this is kinda more like a mini jet engine rather than rocket engine cuz no carried O2...
Your mandatory obligation is to get this machine flying in the next 6 months before FAA drops the hammer and turns every rc craft into mantel ornaments. Superb work ! exquisite complexity at its finest.
Sound is 10/10, would listen again.
The flame isn't igniting in the engine bell. If you do want to sustain it, you are going to need to have a viable control on the butane flow. If the butane can't sustain a flame at anywhere above 40%, you're going to need a tank for the butane that will allow for a higher feed rate.
Enjoying the progress. Thanks for being so smart!
It's just a gas burner. You need a divergent nozzle so the expanding gases drop the pressure after the turbine so it's pulling in more air.
All you're doing there is using your jet exhaust gas to light a flame. When you get it right your fuel consumption will go up exponentially.
Good job so far! Following closely. A couple of suggestions: You might want to look into nitrous jets used in racing, there's a decent range of sizes to experiment with quickly, and you could put them inline with the tubing. Regulating close to the bottle would slow down the butane flow enough for it to stay in the copper tubing longer to gather heat, and give it some room to expand into gaseous state. Also you may want to extend the nozzle so there's more room (and time) for the heat exchanging process without having to block any airflow from the EDF. You also might have to find a way to put it on a little bit of a diet, or double up on the EDFs (which could help solve the torque problem if they counter-rotate).
Looks great , very good reference for practical SFX
Loving the new format.
its soooo cool! one of my favorite channels here! looking forward too all of your cool projects flying!
afterburners need to preheat the fuel.
Combustion chambers bleed in air down the length so it goes from rich to lean down its length
Following your work for a while now..somehow I feel as if I am personally connected in development of these awesome projects..keep it up
On that spiral tube where you heat the butane. Have the last spiral have a few holes evenly spaced in it, and block the end of the tube. This way butane is coming out in multiple places in the combustion chamber. It should make the flame more even.
Your advance is amazing
30 year pilot (and RC pilot) here (non-engineering BA!) but, I am concerned about the butane combustion chamber interfering with a smooth flow out of the fan unit. While you are machining the new vanes, why not have a slim teardrop butane emitter made with like 1/20th the size of the speed taped unit? The fan air needs as few interruptions as possible to be efficient. A tiny nozzle the size of a pencil eraser with a 1/2-1" spike above it would propagate flame well while offering minimal fan inefficiencies due to turbulence. You just need to see a nice flame under the Sprite in flight. Awesome work! Good luck in your flight test phase.
If you get the fuel spray finer I think it would work better. There's a ton of unburned butane dribbling out.
I appreciate the added thrust😂😂
But seriously trying dumping some NO2, or just straight O2 through the stators before it hits the butane for some extra kick.
no need to explain yourself... we like fire
Oh heck yeah!
Looks like your butane is forming fairly large droplets - a finer spray will burn more quickly and stably, hopefully avoiding being blown out. Basically you need finer spray nozzles or possibly inject the butane farther upstream - even before the EDF blades maybe, so they break up the droplets.
Okay that looks great! I recommend focusing on the shape and properties of the fan blades! :)
If you wanted a noticeable increase in thrust, wouldn't you need more of a nozzle? The gas is just expanding in every direction. I realize you know this, but just curious what the plan is if you actually do try and measure it on the stand.
ohhh man this is awesome , joe always inspires me
Man I love that NASA sweatshirt at 6:48 looks awesome!
Something you may wish to consider as ignition of combustables and save a bunch of weight are USB Lighters. they produce about a 7mm constant arc. come with their own batteries and USB chargeable.
With the butane afterburner, why not have the can in the upright position, that way it sends more gas than liquid. I would also recommend some sort of spray nozzle to give a better flame.
Propane would likely work better for producing usable thrust, it's much lower boiling point is a major plus when using ambient temperature to pressurize the tank.
Damn Joe, I'm a big fan of yours.
@JefForking You're hired! Stand on the top of Sprite, for better inlet pressure. :D
I can’t wait to see this fly
I like your videos. It is very intresting and amazing! Keep up the good work.
P. S Sorry for my bad English, I am a russian student)
Joe, what is your real object? To get the hopper flight control system working, or watch a flame? Unless you are going to make a hybrid jet engine with the EDF and a compression/burner section, you might want to pick one or the other.
Also, on those vector fins, aluminum may not be the best material as it will distort from the heat over time. Try making them from ceramic like a thin tile and cut as needed from a big box store.
Cool video!
"Butane fumes" should only be CO2 and H2O, nothing to worry about with the door open as you did!
Hum... Combustion is not perfect, flames are yellow, you have CO as well. Ventilate!
What if you had two EDFs, layered with the lower pitch blades above, forcing air down into a higher pitch EDF, so neither would be working as hard as they otherwise would, and the higher pitch EDF receives more cooling? Keep up the great work, you’re awesome.
I love this video
Are you just injecting the butane with a single nozzle? Perhaps after the preheat turns a full circular nozzle with small holes would be better for injecting into the afterburner? By that I mean that the nozzle has an input after the preheat and then into a full ring of copper pipe (or whatever material it is) and the only ouput for the butane is the small holes.
Aww. He's following in the footsteps of his father!
You can cut weight of Sprite leaving batteries out. Take power from AC, convert it to DC and put a cable to Sprite.
Love your vids. Sprite is pretty amazing, reminds me of the Missile Defense Mutiple Kill Vehicle (MKV-L).
Hey Joe, I love your channel. I think the flame issue is primarily from asymmetric fuel distribution. I’m curious, why do you want the butane oriented upside down?
Are you trying to more closely approximate a liquid fueled engine? I have no doubt you already know that symmetric distribution and ignition is much easier to achieve with a gaseous fuel. Not criticizing, just trying to better understand the goal. Thanks!
Very cool looking forward for it to fly.
Interesting approach: A couple of ideas. . ?
1)What about an inverse "Plugged Nozzle" at front of the firebox?
2) Concrete Patch, or Fireplace cement is an excellent fire shield which can be easily shaped and formed when dry.
Yes, fire cement is cheap, strong and easy shaped for prototyping. Relatively light when dry.
Kit; A while ago, I seen someone using 'Instant Patch to make complete nozzles with. He had a mold milled out of aluminum in the shape of the inner bell with a throat extension, that he sat centered, at the bottom of a tube, then poured the mixture over it. A consistent engine nozzle every time.
Nowadays, a simple 3D printer could do that mold quick and easily. Any modification desired would be greatly sped up, and the cost of the "milling" would be reduced to only some mono filament and the time required to burn it.
Just a fun thought.
David Windestal made an edf after burner for an rc jet years ago, his video should still be on the flitetest page or his but he did manage to get it working. It may be worth taking a look at his successes, and failures.
"What is this? Some kind of plastic ice-cream scoop?" -Harry Stamper
*THUD*
It's cool that super-heating your propellant is trivial to someone inclined at this scale.
Vat vas dat? fthrust chamba instabiliti? auhhahauha...
You look like a younger and skinnier version of Elon.
True
He's his apprentice
My Man, he’s actually a clone of Musk made by the US government.
True bro
@@anthonydomanico8274 Like Jango Fett, Elon Musk had a mini-me made too.
I can't wait for another video
"It's better to look good than to feel good, darling." - Fernando SNL You are so right, Joe. Sometimes the cool factor just wins out over practicality. I am ashamed to say I have also flown some sketchy aircraft in sketchy conditions only for the hope and gamble of some great usable video. Keep up the cool factor... :)
I'm glad you clarified th point of the afterburner at the start of the show 👌
I'm wondering if the heat of the flame will have a negative effect on the performance of the lift fan. Lower density air and such.
I'd look for areas where you can 'add lightness,' to borrow a phrase. For instance, those huge, metal toggle switches on the side could be replaced by something far lighter (albeit, less cool looking). Can you maintain structural integrity on the grey (printed?) parts with less material? Do your fasteners all have to be so chunky? (Those big, pan-head screws...) Have you optimized your wiring to reduce as much extra as possible? (Copper is super heavy!) Could you get by with less zip ties? (Every extra gram helps.) These are just off the top of my head. It gets easy to become locked into a design, and it gets harder and harder to know when to call it good with optimizations, but there seems to be quite a bit left on the table here still. Anyways, thanks again for the vid and good luck!
Fire for effect! Brilliant! Could you add intake vents that double as descent/landing flaps that are higher than the butane ignition point? This may allow for additional air without eliminating the low-pressure zone you’re talking about? It may also reduce your overall weight enough to break the balance.
11:46
Nah, you’re using fancy tape, respect retained!
Heading to Patreon now!
You could probably use a fuel injector of some sort on that thing; I think it would make your butane drip less and be more of a mist, which would not only burn better but it might even burn more evenly.
I appreciate your try.
I'm assuming this was inspired by a certain Flite Test video, is there any reason why the circular tube they used with their butane afterburner is replaced with the nozzle?
And a certain Swede
you could probably put a smaller venturi in the center of the EDF outlet flow path and have a small nozzle (or multiple) that help siphon the butane out. Basically a carburetor. I'm not sure how well it would work with butane, but it's worth a shot and you might actually be able to get better A/F ratios and a little thrust. Maybe even cutting the venturi out of an existing carb and getting a jet kit for it to adjust the nozzle diameter.
My explanation is a bit weird and not the best way to describe how carbs work, but I wanted to be a bit more clear on how they work in case you weren't familiar