Timeline for What is the earliest time a pulsejet could be built?
Current License: CC BY-SA 4.0
12 events
| when toggle format | what | by | license | comment | |
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| Mar 25, 2019 at 19:56 | comment | added | Mark | @JBH, make a lot of noise? A pulsejet isn't much use without either low-friction bearings or lightweight wings, but that doesn't mean you couldn't make one. | |
| Mar 22, 2019 at 4:12 | comment | added | JBH | @Mark that could do what? | |
| Mar 22, 2019 at 1:45 | comment | added | Mark | From a manufacturing standpoint, a valveless pulsejet is extremely simple to build: it's just a correctly-shaped bent pipe. The hard part is working out the theory that lets you design one; I suspect even an ancient Hittite bronze-smith would be able to build one from suitable plans. | |
| Mar 20, 2019 at 17:25 | comment | added | cmaster - reinstate monica | @Eth Well, all the metal does in a pulsejet, is define the intake pipe, the combustion chamber, and the exhaust pipe. The only stresses it needs to withstand are pressure and heat. Pressure can be handled easily by making the walls thick enough, and heat can be handled easily by either attaching cooling fins, or by surrounding the engine in a mantle of cooling water. The later is extremely effective, and should keep metal temperatures to a few hundred degrees. You could build such an engine with pure copper, if need be. | |
| Mar 20, 2019 at 15:37 | comment | added | Eth | Upon searching a bit more, I couldn't find evidence of flying pulsejet using vegetable oil or coal powder. If Greek fire is not volatile enough for fuel, chemists should be able to tweak it/mix it with alcohol/use alcohol instead. Though it seems that the consensus is, metallurgy MAY indeed not be the limiting factor. I didn't expect that! | |
| Mar 20, 2019 at 10:15 | comment | added | cmaster - reinstate monica | Distilled alcohol would seem to be a better fuel than vegetable oil or coal powder: It's quite volatile, and can easily produce combustible mixtures with air. And a distillery is not exactly high-tech... | |
| Mar 19, 2019 at 18:10 | comment | added | JBH | @VilleNiemi, Greek Fire was basically a heavy oil. It's not just flammable that you need, it's bang! | |
| Mar 19, 2019 at 17:11 | comment | added | Ville Niemi | If the limiting factor is fuel then the Byzantines had the infamous Greek fire. It was clearly flammable enough and supposedly made an awful noise when the siphons were used. Admittedly the witnesses were not used to cars and jet engines but it probably had enough energy as well. The arabs and the chinese also got into pyrotechnics and should have been able to make usable fuel if they knew what they needed. | |
| Mar 19, 2019 at 16:41 | comment | added | JBH | @Eth, you can get a plane in the air using a pulsejet running on vegetable oil or coal powder? I could easily be wrong, aerospace isn't my expertise, but I'd like a citation demonstrating that claim. | |
| Mar 19, 2019 at 16:37 | comment | added | Zeiss Ikon | @Eth Surely strong enough -- strength-to-weight ratio is the real question. I've seen pulsejets built from iron plumbing pipe, as well as EMT conduit; the latter don't last with the heat, but they're plenty strong until they rust out. Pulse jets run pretty low pressure. | |
| Mar 19, 2019 at 16:22 | comment | added | Eth | Pulsejets can run on vegetable oil or coal powder, so fuel should be available to the Romans. But would Roman bronze or iron be strong enough? | |
| Mar 19, 2019 at 14:59 | history | answered | JBH | CC BY-SA 4.0 |