51 thoughts on “Make A Ramjet Engine

  1. From the article, I see that the design and assembly for this was completed late last year. Unfortunately I do NOT see anything about testing other than to say “Not started”.

    Call me a wee bit pessimistic, but before I start lighting up fuel in a combustion chamber, I’d like to know that it won’t blow a hole through my garage.

    What is the projected thrust from something like this? 15kg? 25?

    Having said all of that, it’s a pretty cool concept (visions of mounting three or four on a car, even if the actual thrust is minimal, it’d LOOK really geek).


  2. I couldn’t help but notice that there was a lack of any type of data on this thing operating. Perhaps the author blew himself up before he could put further data on the site(?). It is a very kewl concept though.

    Some one please try this and let us know if it works or burns your neighborhood down

  3. I have never really done much (read: anything) with jet engines before but I would like to try to build this. The build is relatively straight forward but some details are left out like what is the guage for, how much air needs to be travelling through before the jet can be started, how much thrust, and more info about fuels. I think this would be really cool to add to a model airplane. Could it work almost as an afterburner???

    1. This design would never work as a ramjet. But lets say it did fire up even though all the dimensions are so incorrect as to be zany, after it fired the Epoxy, even high temp epoxy would lose bonding strength in about one second after the housing reached 300 degrees f. I too would love to see a cheap DIY jet or throttable (not a hybrid) rocket motor hit the net, but after ten years of searching there seems to be no easy cure for that ache of mine and it seems of many of my fellow hackee’s. Looks like I am going to have to design test and fly one before I retire!

  4. Doing some reading on the creators site (http://jetzilla.com) I came across a mention that it might take a constant air source of about 60 mph to fire up this engine. He mentioned a leaf blower. This might be possible on a RC plane but I don’t think a boat would be even close to fast enough.

  5. I just got a long detailed e-mail back from Larry Cottrill, they goy that made the engine. He said he ended up getting into otherthings and that is why he has not updated the site. He also said he was surprised to see that people are interested in this engine.

    One of his concerns is how well the glue will stand up to extended high temperatures. He did mention he now has a device that he can use to measure the thrust and he may fire the engine up with this device (fueling the engine with propane). hopefully we will get to see his results.

  6. Is anyone actually thinking about building one of these? I kind of am. I think that it’s questionable whether the JB Weld and even the thin steel mug would hold up to the kind of heat you would see from the flame. I was thinking that you could use an electric blower to fire it up. A lot of other people that have made jet engines have put turbochargers on them. potentially this would allow you to supply the 60mph air input and would not require a separate compressor(after you have the engine started).

    It looks really, cool I want to try it. Don’t know if I actually will though. Anyone else have thoughts?

  7. Considering that some amateur ramjet engines make steel glow cherry red, I wouldnt trust that kind of bonding glue.

    I would however still like to make one, but I would actually to some TIG welding on it. It seems a straight forward design, and you just need to use a leaf blower to get it going, just like you have to do with other ram jet engines.

  8. Ram jets are used as a secondary engine on things like the SR-71 blackbird but the engine already must be moving at great speed in order to get the needed amount of air into it. they are usualy used to boost the speed of something that uses a turbojet as its primary engine there is no way you can strap this thing to anything and make it go by itself. there are plenty of websites about making homemade turbojets the simplest ones usualy use a car turbocharger. that being said you could probably bolt a bunch of these to your car and fire them up on the freeway.

  9. sounds cool,

    would be fun to see one (or more) of these on a skateboard or somthing, of course you would need to use a leaf blower to start it up but, once it got going it would be cool

    might give it a go myself

  10. Hey, I’ve been working on building one of these with a teacher at my school. We made some modifications to the stand that Larry Cottrill proposed, as well as the fuel injection. As a matter of fact we used straight liquid gasoline as opposed to propane. The JB Weld actually held up pretty good for about a minute of focused burn, then it itself burnt. If anyone’s interested, there are some pix posted here:

  11. I street luge. I’ve gotten in the 70’s. Think street luge mounted ramjets!!! Do you think it would work? What could go wrong? If I do make it I’ll post pics. I’m going 2 make a lot of them before I mount one on a thing i’m riding. LOL

  12. Hi my dear friends up there…how are you?
    I am too much interested in ramjet engines.I would like to make my own ramjet engine but I have nobody to help me.First it looks easy but when you start the job,….
    Is there any body to show me how to make it?
    I will be waiting.

  13. hello group, i have just built this maggie mug ram jet over the thanks giving weekend. it only took me 6 hrs to make the whole thing. i brazed welded the stainless parts together using alloy rod and a mini oxy/mapp gas rig. this should cure the overheating problem with the jb-weld. i tried to fire the ram jet up using propane and then mapp gas with my kirby vac set up to blow (i know dont laugh). i failed to get a good burn though. i think my fuel supply volume was not enough and air supply to slow. so i think i will have to increase both for a good quality burn.

  14. i am using the ramjet idea and combine it with the steamjet to build an underwater propulsion system using the coolingwater of the engine and the exhaust pipe heat to increase the steam volume it should give me a considderable increase in hp i expect 20% increase your comment appriciated regards gerry

  15. thank for your quite information that i find them in your websie . but this study on jet engine cause some question in my mind. please help me on this manner.
    in ramjet that is suprise me because i think the price of it is too smaler than other jet engine that have turbine and compressor that all of the are dynamic parts and so high technology for product exact all blades (titanium and inconel).
    bu i think ram jet can work in high speed (super sonic) and can not be use for start motion . my question is if we use tank that contain oxugen with high presure and we put some tubes to inlet of our combustion . can we have motion in start??? in other word this oxygen flow that cause a presure aprox 5 bar in combustion can work as aire in super sonic motion for ramjet and after going up the speed we reduce the oxygen flow and in final (super sonic) cut the oxygen flow???

  16. If you have a problem with ignition, and need something CHEEEEEEEAP to use for the Spark, get yourself a CHEAP Hand Held Stun Gun, and take the guts out if it. They supply anywhere from 20,000 to 200,000 volts. This would ignite fuel real easy, and could use a servo to turn it on and off. Also, you can get HeNE Laser power supplies that produce about 4k volts for under $30 and run off 9 to 12 volts.

  17. I have a working ramjet for sale, or plans if needed. It is made from stainless and mild steel. It runs on unleaded gas it is 7.25 in. in dia by 55 in. long. Nozzle can be adapted to various velocities. Great engine to learn how ramjets work. Made for a street luge project.

    Contact; voyagerwsr@aol.com

    for price and photos.

  18. This 55 inch long Ramjet is for sale. $300.00 plus shipping. It runs on unleaded gas and was built for a street luge. Neat flames. Shown with the inlet disconected . Flame holder is vee gutter type. This is the best Ramjet to leard with. And it is the only one like it on the web. Contact Voyagerwsr@aol.com

  19. big, red “FAIL” stamp complete with sarcastic picture for you.
    Ramjets require supersonic intake air to function, and you won’t get that on a static test bed, street luge or back harness (unless you want to be turned inside out by it). Sorry, should’ve kept the glue for something else and left the insulated mugs in the camping box.

  20. I would like to make my own ramjet engine but finding simple plans is hard to fine. I wish the had a book called The Complete Idiots Guide to building a ram jet engines. Dose any one know a good place to find easy detailed plans for ramjet engines?

  21. I’m sorry, but this will never, ever, work. I wrote my dissertation on ramjet engines for my Ph.D. from the Massachusetts Institue of Technology in Aeronatical Engineering, or in other words, rocket science. The combustion chamber is not large enough to obtain the proper fuel/air ratio, the inlet does not get the air to a subsonic-high friction state, so no combustion can occur. The exhaust tube where the nozzle should be, but isn’t, is not even close to being long enough. And there is absolutly no propposed means to get the ramjet moving to a speed at which there would be combustion (which there would never be). And that is why there is no data as to how many pounds of thrust it is capable of or anything else.

  22. Hey, that’s a pretty cool project. I saw some videos a year or so ago of it running. I think they used propane and a shop-vac, but it’s kinda hard to remember such details that far back.

  23. Hi Guys:
    The SR-71 DOES have a ramjet engine… The turbine engines shut down at hign mach number and the ramjet, which is ducted around the fan & turbine, takes over for the higher mach numbers.

    I am building a series of small ramjets for R/C aircraft. So far I have 1″, 2″, & 3″ diameter engines. None have been running yet, waiting for the weather to allow me to run outdoors (they DO blow-up!).

    I worked on ramjet engines at Marquardt in Van Nuys CA from 1960 to 1976.

  24. Ramjets DO work at subsonic speeds, they are just not very fuel efficient.
    The ramming effect begins at about 120-200 mph (hence the leave blower for static runs and starts) and increses with the intake velocity as (V*V).

    Ramjets supercede turbo-jets in efficiency around mach 1+ and achieve peak SFC [specific fuel consumption] at mach 3.5 and @ 90-100K feet in altitude, -70 degrees below zero.

  25. @google

    Could you fly? These are ramjets, which only work once they have air moving through them; about 60 mph if what I’ve read here is accurate. Unless you plan to jump off a tall building, you won’t get enough air moving through these things to get them to work. Acceleration due to gravity on Earth is about 32 ft/sec^2, so…

    60 mph = 88 ft/sec
    32 feet after 1 sec
    64 feet after 2 sec
    96 feet after 3 sec

    After freefalling about 180 feet, the ramjets would start working. The faster you go, the better they will work.

    After saying all this… No these won’t let you fly. If they did, someone else would have already done it.

  26. Yes, you can strap one of these on your back to fly. But you need to stuff it full of solid fuel and a disposable nozzle. (The nozzle is automatically ejected when the final rocked fuel is burnned up)

    The short burst of rocket fuel gets you close to the speed of sound, then the ramjet takes over.

    One word of warning: You need to have good ear protection for the sonic boom. (It might be a good idea to think about how to land as well)

  27. even if you have a working ramjet for use on rc anything how would you begin to control at scale to fast you would need miles and also radio reach wouldnt be enough its likely to kill someone if its not controled correctly

  28. The Maggie mug is a pressure jet and you are correct that you have to get air moving through the engine at high speed consistantly in order for cumbustion to happen to create thrust. One very successful pressure jet is an athodyd jet used on the Hiller hornet helicopter. Their are videos on youtube and plans on ebay. In one video you can see that they spin up the rotors with a heavy duty drill. But this was in the 1960s. Now you can run the rotors up using a pre-rotor unit powered electrically using a heavy duty motorcycle battery or lawn tractor battery or a small gas engine can be used. This can get the rotors up to speed in ignite the engines and produce thrust to run up to maximum thrust and rotor speed.

  29. there is one major problem with this to start it u need it to travel around mach 2 to get the right air compression to get any thrust at all so its basically pointless to build unless your showing a class how a ramjet works

  30. how could I build a ramjet that I could connect to the bottom of a car lie k.i.t.t. from knight rider it would give it the power to make it airborne. I want to connect it to the go kart I`m making. so how could I make one that actually works. if its possible, and what would the price range and parts be that I would need.

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