Step 6: Make Your Ducted Fan Adapter

Take the other piece sheet steel you made and roll it into a tube/gentle cone around your ducted fan unit. Secure this end in place with tape.

Take the other end of your sheet steel tube and put that into the cone coming out the back of your engine. Secure this end in place with tape. Then use a stapler as previously described to secure this end, Duct tape cannot take the temperature.

***Note, most of the pictures in this instructable were from my mark II jet engine hence the hole in the cone which shouldnt be there in this version, and the combustion chamber with no copper tube input. unfortunatly these are the only photos currently available but i will replace them asap.***


hey any ideas for ignitor <br>&amp; here r some pics of my next jet the &quot;turbojet&quot;
Hey! Seriously awesome. But i had this doubt that will the turbine and compressor be efficient if u use that metal strip to hold that shaft ??? Woudnt bearings be better? And will they be able to withstand the temperature ? If yes then how to use them?
Bearings would be better. The centre of the fan blade does very little in the way of moving air anyway, so the circular space they take up shouldn't make too big a negative impact on performance.<br><br>You would probably have to use Ceramic bearings, and use a cold air by pass to cool them. <br><br>If the metal strip was orientated in line with the air, then it would be much better. You could also use a very stiff prop shaft, and have bearings in the air intake only. So the hot tail end doesn't need any bearings.<br><br>Modern turbo fan engines have a large proportion of blow by design.<br><br>Wikipedia has a good cross section:<br>https://upload.wikimedia.org/wikipedia/commons/thumb/7/77/Turbofan_operation_lbp.svg/1280px-Turbofan_operation_lbp.svg.png
Hey! Sorry to disturb again but i have some seruous doubts and i want to make one dearlt. So :<br>#1. Does a turbojet have a motor? I see u have used one but i generally see or atleast have concluded that the fan is usually connexted to the shaft? But i can use the motor. But which type? Wont it get turned yo liquid cuz of the heat?<br>#2. I really dont understand how prop shadts work. I googled it but still no idea. Could u plzz explain? Or do i use to bearings?<br>#3. About the compressors and turbines. Are the compressors inside the focused inlet [combustion chamber ] or fuxed before it?? I read that smaller the compressor the faster it rotates. So i could keep the compressor inside but where do i put the turbine?? Inside or outside? <br>Thanks for ur time.
<p>#1. My design does have a motor. It's technically an after burning ducted fan. Rather than the stereotypical turbojet. Mine is from a hair dryer. An Electronic Ducted Fan (EDF) designed for use in model aeroplanes would be ideal. They're Brushless DC motors, which require an Electronic Speed Controller (ESC) to run. HobbyKing is a good website for these. The motor won't melt because it is in front of the air intake. It has cold air drawn over it constantly. It's the exhaust of the engine that could melt.</p><p>#2. It's just a spindle that runs down the centre of the can. You could use two bearings at the intake to stabilise it, and none in the rear. This is what attaches the turbine blades in the exhaust to the compressor blades in the intake.</p><p>#3. Both are inside the can. They will be spinning at the same speed because they are both attached to the same spindle/prop shaft.</p>
I seriously dont want to use bearing at the hot tail..so plzz tell me bout the prop shaft and where do i find it...
And Can u plzzzzz send me ur detailed plans for this engine at quanta8714@yahoo.com
nice pictures. you just gave me an idea of how to secure the central shaft. <br>here's my improved design
<p>looool same i didnt know how to do that....</p>
you can use a spark generator from one of those lighters where you have to push a button. just dismantle it without puncturing the gas store and extend the wire between the spark gap and the generator (if there is one). it would be like a spark plug.
Looks interesting, what are you using for bearings?<br><br>As for the ignition, the standard solution is a spark plug that screws into a boss welded onto the side of your combustion chamber, you would need a coil pack and a decent 12V source like a lead acid to run it though. Another option is to use the spark of a disposable lighter, extend the wire into the can and set the wall gap right. You could also use two bolts that are screwed in from opposite sides of the combustion camber with a small gap between them and discharge a camera flash circuit through them to give a nice beastly spark.
I finished it! i made a video of it here: http://www.youtube.com/watch?v=yPvhfkExAlU&amp;list=UU6q74pDLeZFgsPFzckC0MOQ&amp;index=1&amp;feature=plcp<br>
Nicely done! I managed to wedge bits of mine together and use jubilee clips to avoid the smoking tape issue. <br> <br>It looks like you either aren't putting enough fuel in or the fuel ring isn't spraying evenly, to solve this you can try drilling more holes in the fuel ring or add turbulators to the part of the engine the air and fuel mixes to help them mix better. <br> <br>Keep me updated! <br> <br>LBO
most amazing thing i have ever seen done with peoples old crap. I am going to make this for a school project about re-cycling and re-use, any advice about the type of hair dryer and where i can get one?
Any hair drier will do. The more powerful the better. Power is probably relative to physical size and any power rating though I doubt there is much between them. you could try your local re-cycling centre.<br><br>To be honest an Electric ducted fan is probably cheaper and more effective than a hair drier if your going to buy one. They can be picked up for around &pound;15-20 new. You could try ebay, markets, car boots and similar to find a cheap one. I recently bought a Nitro boat with all radio gear and all accessories for &pound;40 from a market. A similar EDF plane should be much cheaper.
ya ty for that i got myself a hair dryer from argos. my next problem, however is finding the pipe used for the fuel injection ring. I went to B&amp;Q at the weekend but the only 5-8mm copper pipe they had was &pound;22.60 a roll! what a rip we dont have any at home and the DT department at school has none either. Where can i get a foot length of 5-8mm copper/steel/brass tube before wednesday?
A scrap yard will have some, it's what they use for brake pipe on cars. They usually let you clip off a few feet for free. Though this may be steel and harder to bend. If you go to a garage then they usually have a roll that they may give/sell you a foot of.
ya does it have to be 5mm cuz i found some 8mm cheap and bought it.
That can work... You may have trouble bending it tight enough so you might want to bend it so it;s central in the can, seal the end and drill your holes around the circumference. similar to my M2 engine but without the aluminium part.
ok ty the jet is awesome im going to start building on the weekend when we can get an replacement hair dryer from a charity shop or pawnbrokers (mine was modern and had a circuit board, and when i tried to re-wire it, it blew up).
Yeah, they often have the heating element in series with the fan so if you remove it the fan gets over volted and blows up... In future leave the heating element in. If it has a cold air setting then I'd follow the wiring and isolate it. Alternatively you could always leave all the electronics in and not re-wire it?
is the throttle of the engine controlled by the switch on the hair dryer
No, it uses a dimmer switch off a light. This was a bad solution though and PWM or a speed controller would be better.
if your testing this enjine somewhere like the beach where should i get my power source for the hairdryer. <br>
You could use a lead acid battery and an inverter. alternatively, if you remove the heating coil you can run the electric motor off a few batteries in series. You will need 24-50v though.
how much thrust is there?
Around one or two pounds, (500g-1Kg).
best way to deal with MDFs and Plywood - use a hand tube saw<br>
can you give me any instructable for building a pulse jet for mounting on a rc car or a plane n can u tell how to increase the speed of a motor
I have never built a pulse jet as they are illegal in my country. I think you can increase the frequency by making the tail shorter and or thinner diameter but you need to be careful as those dimensions are crucial to the engines operation. Higher power from a bigger engine, higher frequency (speed of running engine?) from smaller engine in general terms.
Where do you get the idea pulse jets are banned from ?
I'm not sure to be honest. Maybe scrapheap challenge? The noise is apparently too much for the British public.
are the blade designes for my compressor and the turbines are okay or not? <br>i also have a old insect slayer would it give out some beasty sparks for ignitor
You're blades aren't ideal as they have no aerofoil section to them and both the ones labelled &quot;1&quot; look to have too much camber on them but I would speculate that they may do the job. Also the relative diameters and numbers of blades look a bit off but they should still work.<br><br>We don't have a big problem with insects in England so I have never come across an &quot;insect slayer&quot; before and as such couldn't comment. Give it a go if it'll cost you nothing though because then at least you can tell the rest of us whether it'll work!
hey have any idea about making this type of ignitor without using disposable camera <br>http://www.youtube.com/watch?v=iSvDZok-zdM
Yes, it can be done but it seems a bit complicated for what it does. It would be much easier and simpler to go to a film development shop and ask for an old disposable camera. They give them out free and are ready built and ready to go.<br> <br> If you really want to build one like that then you probably want to look at building a <strong>step up buck-boost converter </strong>using a transistor with a secondary output from your transformer coil to trigger it. It's a lot more work and probably won't do the job any better though.<br> <br> If you want a beastlier spark than the flash circuit gives add two or three AA batteries on your camera flash circuit. This will step your voltage up from just under 400v to over 1000v. Your flash cap will probably die though as they're only rated to 330v so you'll want to take that out or, if your feeling lucky, put another cap in series with the&nbsp;original&nbsp;one for each of the extra battery you use to split the voltage.<br> <br> Be careful when messing with these high voltage circuits as they give a nasty shock and CAN KILL if you get shocked across your heart. Wear some rubber gloves and insulate everything before you connect the power source. This isn't worth dying over some simple safety precautions.
hey any ideas for ignitor <br>&amp; here r some pics of my next jet the &quot;turbojet&quot;
hey LBO i have sm pics of my thermo jet engine
Hey kgaurkhede, Thanks for the pictures. Do you have any of it in action?
hey LBO i have just made my own beer can jet engine but not using the beer can its actually hard to find here! ( coz i live in INDIA ) <br>so i've used empty deodorant cans instead n some small steel cans <br>and for air flow system i've used a simple 12volt dc motor with a fan but there is one problem, i cannot get much speed from this motor. can u help me out with this? and ha the motor is taken out from a toy car!!! <br>for fuel i used another deodorant but it was almost empty! <br>so when i ran the engine so it lasted for only 10sec now i will try other alternative fuel ( maybe using acetone ) <br>hope you would feel happy <br>
Hey Kgaurkhede, <br><br>Empty deodorant can's are a perfect replacement. If you overvolt the 12v motor you will get more speed from it as the rpm is proportional to the input voltage. It is usually safe to over volt by 50% so 18v would be a good place to start. I have however overvolted a 12v motor to 48v previously to no ill effects so it's down to how brave your feeling as to how much extra. Be careful though, the higher voltage you put in the faster it will get hot and the hotter it will get, if you put too much voltage through it for too long you will cook the engine and it will no longer work.<br><br>Deodorant would be a good fuel source, they usually use propane or butane as a propellant so it is as good as using a can of butane or propane. They even come with a decent atomising nosel on the can! The downside is they are low capacity and you have to press the button up close to the intake of the engine which is dangerous and makes RC control difficult. Acetone would be a good alternative fuel. You just have to pre-heat it before it gets into the combustion chamber and use an atomising nosel to disperse it into a fine spray so it will burn efficiently. This will require a pressurised fuel system you'll have to work out by yourself.<br><br>Thanks for building one! Please can you send me some pictures or a video?<br><br>All the best<br><br>LBO
hey can i use ceramic coated aluminium cans instead the steel one <br>
I didn't know you could get ceramic coated aluminium ones? The Ceramic would be fine but the aluminium will probably melt although it depends on the composition. Try it and find out? Please tell me how it goes.
thank you very much
This still doesn't work 100% of the time.&nbsp; I used steel cans and they still melted.&nbsp; I am trying a new design with purpose made parts.&nbsp; I have most of it machined out but I wanted to do this right so I wanted to have the exhaust fan driving the compressor fan at the front but I wanted to know, would the bearings seize up?&nbsp; I was going to enclose then is a metal tube but will they still heat up and seize? <br /> <br />
Really? I'm impressed! Did you run it for an extended period of time like five minutes or more? I used to run mine for no longer than a minute or two at a time because I was worried it was going from glowing orangey white hot to molten. Are you using Butane? Some other fuels burn hotter than butane.<br /> <br /> I found that Mine distorted less when I wrapped a second can around the first. The Videos for my mark II Engine aren't uploaded yet but when they are you will see my augmenting nozzle and how it acts as a heat spreader for the combustion chamber. Maybe adding some kind of heat sink is something to consider.<br /> <br /> As for your question on bearings, yes. A normal ball bearing ring race would seize at the exhaust temperature so you have three options;<br /> <br /> First use ceramic bearings that can withstand a higher temperature but you need to make sure they can hold up at several thousand and potentially tens of thousands of rpm and they are expensive and relatively difficult to get hold of in the size you want.<br /> <br /> Secondly shield your exhaust bearing in a jacket. Essentially having a 1/2&quot; tube down the center of your engine that the bearings sit inside of, maybe with some cold airflow from the compressor blowing down it.<br /> <br /> Your third option is to use two or three bearings before the combustion chamber and leave the exhaust with no bearing. This relies on the stiffness of your central axle to hold the exhaust turbines blades central with a restraining ring as a safety. This is my plan and by far my favorite of the three options.<br /> <br /> Good luck and keep me updated,<br /> <br /> LBO<br /> <br />
I was using gasoline and this happened in less then 20sec.&nbsp; It melted very quickly.&nbsp; I thought it would have held up better.&nbsp; Fun to watch though...&nbsp;&nbsp; : )<br /> <br /> I was thinking of doing as you said, having the bearings up front and having a sturdy axle for the exhaust fan.&nbsp; I was still going to enclose them anyhow for added security because the are regular bearings which I wanted to use cause I have lots of them (FREEBIE!).&nbsp; I have a metal shell for the engine, it happens to look like a metal version of a glass bottle Coca Cola, but I was going to make a second shell, just a metal tube to direct some air flow over the actual combustion chamber in hopes that it will stay cooler.&nbsp; The combustion chamber is made of&nbsp; steel but is at least 5x thicker then beer cans.&nbsp; Still working kinks out of the fuel sprayer, and I would like to find a small fuel fuel, but I don't think they have one as small as I would like.&nbsp; <br /> <br /> Most jet engine that they use on planes force the air around a central...thing...I think its usually the shaft that turns the compressor and exhaust, but it has to inject the fuel in a ring.&nbsp; I designed mine so that the air is compressed into a central space and injected with fuel from only one nozzle and I hoped that would make the fuel system easier to construct.&nbsp; I added a picture of a drawing of an actual jet engine and even though its 2-d and cut away you can see it has 2 combustion chambers which would actually be a bunch all the way round.&nbsp; Do they do this for a reason?&nbsp; The second picture is my first rough draft of what I was thinking about and it only has one centralized combustion area.&nbsp; Do you think that one will produce more power or operate better?<br /> <br /> Thanks<br /> <br /> Will keep you posted, and I might make an Instructable if it goes good!<br />
Thats strange, thermodynamics says that Gasoline burns at a maximum theoretical temperature of approximately 2500&deg;F. The melting point of soft steel is about 2500&deg;F... So it is possible but I'm surprised it happened.<br /> <br /> They use multiple fuel injectors on a comercial jet engine to ensure equal combustion through the combustion chambers cross section. They can't use a central one due to the prop shaft being there. The breadth of the combustion chamber and thus the diameter of the spray cone from the nozzle at combustion point dictates that in order for the whole cross section to maintain balanced combustion, several nozzles are need around the perimeter. Your design is fine, the central combustion chamber is ideal and as long as your nozzle is capable of delivering enough fuel to the engine then you will not need multiple nozzles.<br /> <br /> I like your design, I can't fault it, having said that my only concern is that you are being too ambitious about the compressive capabilities of your fan. That is a very large throttle on the exhaust so I may be worried about getting flash back. <br /> <br /> I'm curious, how did you make/where did you aquire your fuel nozzles and are they aspirating or atomising? Also if you use a fuel pump what is it? my next engine should be gasoline powered but I'm having some difficulty with the affore mentioned issues, any experience or insight you might have would be really helpful :). <br /> <br /> Thanks<br /> <br /> LBO<br /> <br /> <br />

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Bio: I build stuff because it isn't available to buy, or is too expensive, or the ones you can buy don't do what I ... More »
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