The optimal nozzle configuration changes as the speed of the propelled vehicle increases. At subsonic speeds the nozzle is constrictive, and becomes ever expanding until at many times the speed of sound the nozzle is most efficient when it is surrounding a thrust body. Like a coanda thrust body configuration. I would think It would require huge amounts of fuel .Great channel.
Isn't the PDWE supposed to burn the fuel on the outside of the craft? This way it can create the aft conical bow shock wave, "the air spike", to let it travel through the turbulence at mach 8?
I think you are talking about the external burning concept that has been studied mostly for scramjet engines and hypersonic airframes. I don't recall seeing any design attempts to integrate it with a pulsed detonation engine, and I think it would be difficult because the external aircraft aerodynamics need to be stable while the engine is cyclical.
@emb8 in terms of design, we have a solid way to start DDT in our engines. the only problem now is damage and heat. for heat, we use the materials used in the HISTED engine which allowed a turbojet to have 6 times the specific thrust that a j58, and get arrested for possessing such material. the second problem is the spring, we will instead turn shchelkin spiral, into a shchelkin threading (like a female bolt), sacrificing cost.
@emb8 (continued) now for the valve; get four superalloy plates, and put two of them on a axis placed up front, positioned parallel to the engine. behind those two is the other plates placed horizontally to the engine. both front and back plates will rotate with each other, kick started by a small motor (that will not run forever), and carried on with detonations. all four plates, will only be half exposed to aerodynamically; i don't know how to explain this very well.
I suspect this is the ground work for the Arora , skunk works plane that is SUPPOSED to be top secret , leaves a distinct con trail , Pearls on a string or string of doughnuts . I have only wittinessed the doughnut con trail one time , Some say at mach 6 the doughnuts turn into a corkscrew con trail
This may go a lot slower e.g.mach 4 - 5 but the time lapses of ignition preserve fuel perfect for long range spying missions and the SR-71 proved that it would be hard to hit going at this speed, so i beleive this would be used on the aurora and if not maybe a scram jet.
I may have misinterpreted the comment. I thought you were saying as PDE would be used on a scram jet but I guess you were saying that the Aurora may use a scramjet.
the Fractional lapse of propulsion between pulses; is this considered a significant loss of thrust? It seems like the same pricipal behind a machine gun without the projectiles..one other thing about the Aurora...how could you possibly be a stealth plane with that kind of noise, even a larger diameter would create subsonic frequencies totally detectable...
I believe there are some studies that show a high enough pulse frequency will create thrust that is essentially constant. Regarding the Aurora, it would be noisy but the stealth structure, high speed, and high altitude would make it very difficult to hit. The SR-71 had thousands of missiles fired at it but none of them ever got close. If anything, the Aurora was probably an upgraded, highly efficient ramjet, similar to the SR-71 only capable of Mach 4 to 4.5 or so.
As well, the experimental models currently being tested for flight use use multiple tubes at a much higher detonation rate, so that there is no perceivable loss of thrust
This is all detonation. It is repeatable because of valving that can be rapidly actuated, along with a purge cycle that clears the engine of fuel between detonations. Once detonation is initiated, the wave propagates through the tube in less than a millisecond, so frequency is mostly dependent on fill times for the purge and fuel cycles. Again, proper valving and control can allow for detonation frequencies in the 10's of Hz.
Yes the noise would be detectable... but by then a hypersonic or near hypersonic craft would be long gone by the time sound-waves reaches the unit or person that detects the noise.
I have nothing to prove or disprove the existence of the Aurora aircraft, but I'm 100% certain that it could not have had a PDE propulsion system. The U.S. government has a history of developing and testing new aircraft years before they are revealed, but PDE's are still too developmental. The AFRL has publicized their own research that is similar in development to the engine in this video, and it doesn't make sense why that would be funded if the government had something else more advanced.
Essentially there are two types of combustion: deflagration and detonation. Deflagration is seen with everything from grills to commercial jet engines and propagates at a subsonic speed. On the other hand, detonation is supersonic and creates compression waves. Applying detonation to engines is difficult because it must be pulsed, the ignition system and fuel addition must be timed, extreme noise and heating, etc. However, it releases more energy and can be significantly more efficient.
GREAT INFO!Any stats on the thrust per pound of fuel for pde vs say turbo fan etc?I wonder if it would be possible down the line for VTOL supersonic PDE aircraft.Thanks!This info Ive been looking for for years!
You can probably find a chart of specific impulse (Isp) for all of the engine types online which is close to thrust per pound of fuel. High bypass turbofans have a higher Isp than PDE's, but the Isp of a PDE is greater than a mixed flow turbofan beginning around Mach 3. Theoretically you could build a VTOL PDE, but the shock waves from the engines might reflect off the ground during liftoff and damage the aircraft. But it would still be fun to try.
The optimal nozzle configuration changes as the speed of the propelled vehicle increases. At subsonic speeds the nozzle is constrictive, and becomes ever expanding until at many times the speed of sound the nozzle is most efficient when it is surrounding a thrust body. Like a coanda thrust body configuration. I would think It would require huge amounts of fuel .Great channel.
snappyboy1 8 months ago
That is awesome .. you can see the flame spit h2o vapor .. I wonder if damp weather would increase your burn ?
MrMicraphone 10 months ago
Sounds like an mg42 lol
Bamchucknorris 1 year ago
Isn't the PDWE supposed to burn the fuel on the outside of the craft? This way it can create the aft conical bow shock wave, "the air spike", to let it travel through the turbulence at mach 8?
smilingpug 2 years ago 2
I think you are talking about the external burning concept that has been studied mostly for scramjet engines and hypersonic airframes. I don't recall seeing any design attempts to integrate it with a pulsed detonation engine, and I think it would be difficult because the external aircraft aerodynamics need to be stable while the engine is cyclical.
emb8 2 years ago
@emb8 i think it is called the pulse detonation wave engine.. i think not to sure
nickcars100 1 year ago
@emb8 in terms of design, we have a solid way to start DDT in our engines. the only problem now is damage and heat. for heat, we use the materials used in the HISTED engine which allowed a turbojet to have 6 times the specific thrust that a j58, and get arrested for possessing such material. the second problem is the spring, we will instead turn shchelkin spiral, into a shchelkin threading (like a female bolt), sacrificing cost.
askingstuff 1 month ago
@emb8 (continued) now for the valve; get four superalloy plates, and put two of them on a axis placed up front, positioned parallel to the engine. behind those two is the other plates placed horizontally to the engine. both front and back plates will rotate with each other, kick started by a small motor (that will not run forever), and carried on with detonations. all four plates, will only be half exposed to aerodynamically; i don't know how to explain this very well.
askingstuff 1 month ago
@smilingpug i think it is called the pulse detonation wave engine.. i think not to sure
nickcars100 1 year ago
I suspect this is the ground work for the Arora , skunk works plane that is SUPPOSED to be top secret , leaves a distinct con trail , Pearls on a string or string of doughnuts . I have only wittinessed the doughnut con trail one time , Some say at mach 6 the doughnuts turn into a corkscrew con trail
wizardman42 2 weeks ago
Holy crumoly!... need specs!
charrisgw 3 years ago
This may go a lot slower e.g.mach 4 - 5 but the time lapses of ignition preserve fuel perfect for long range spying missions and the SR-71 proved that it would be hard to hit going at this speed, so i beleive this would be used on the aurora and if not maybe a scram jet.
OBLIZOX 3 years ago
a scramjet is a type of engine, not aircraft.
miked860 2 years ago
*Claps
OBLIZOX 2 years ago
I may have misinterpreted the comment. I thought you were saying as PDE would be used on a scram jet but I guess you were saying that the Aurora may use a scramjet.
miked860 2 years ago
i have the PDF document of to how this made anyone want it
grenade0wnyou 3 years ago
I want it. zerofossilfuel at gmail*com
ZeroFossilFuel 3 years ago
YES!
imagod117 1 year ago
the Fractional lapse of propulsion between pulses; is this considered a significant loss of thrust? It seems like the same pricipal behind a machine gun without the projectiles..one other thing about the Aurora...how could you possibly be a stealth plane with that kind of noise, even a larger diameter would create subsonic frequencies totally detectable...
NovaNeolith 3 years ago
I believe there are some studies that show a high enough pulse frequency will create thrust that is essentially constant. Regarding the Aurora, it would be noisy but the stealth structure, high speed, and high altitude would make it very difficult to hit. The SR-71 had thousands of missiles fired at it but none of them ever got close. If anything, the Aurora was probably an upgraded, highly efficient ramjet, similar to the SR-71 only capable of Mach 4 to 4.5 or so.
emb8 3 years ago
As well, the experimental models currently being tested for flight use use multiple tubes at a much higher detonation rate, so that there is no perceivable loss of thrust
MidnightWyvern 3 years ago
This is detonation not deflagration right?I think its quite an achievement that they can repeat it so fast.
tomterahedrob 3 years ago
This is all detonation. It is repeatable because of valving that can be rapidly actuated, along with a purge cycle that clears the engine of fuel between detonations. Once detonation is initiated, the wave propagates through the tube in less than a millisecond, so frequency is mostly dependent on fill times for the purge and fuel cycles. Again, proper valving and control can allow for detonation frequencies in the 10's of Hz.
emb8 3 years ago
Yes the noise would be detectable... but by then a hypersonic or near hypersonic craft would be long gone by the time sound-waves reaches the unit or person that detects the noise.
Lightcycle 3 years ago
aparantly the deltoid SSP "aurora" uses this...
but on a a much grander scale, of course, and faster pulse time (thousands per second).
AustralianPyro 3 years ago
I have nothing to prove or disprove the existence of the Aurora aircraft, but I'm 100% certain that it could not have had a PDE propulsion system. The U.S. government has a history of developing and testing new aircraft years before they are revealed, but PDE's are still too developmental. The AFRL has publicized their own research that is similar in development to the engine in this video, and it doesn't make sense why that would be funded if the government had something else more advanced.
emb8 3 years ago
Wow what principles are behind this? Do you have detailed plans of assembly?
anewlow23 4 years ago
Essentially there are two types of combustion: deflagration and detonation. Deflagration is seen with everything from grills to commercial jet engines and propagates at a subsonic speed. On the other hand, detonation is supersonic and creates compression waves. Applying detonation to engines is difficult because it must be pulsed, the ignition system and fuel addition must be timed, extreme noise and heating, etc. However, it releases more energy and can be significantly more efficient.
emb8 4 years ago
GREAT INFO!Any stats on the thrust per pound of fuel for pde vs say turbo fan etc?I wonder if it would be possible down the line for VTOL supersonic PDE aircraft.Thanks!This info Ive been looking for for years!
tomterahedrob 3 years ago
You can probably find a chart of specific impulse (Isp) for all of the engine types online which is close to thrust per pound of fuel. High bypass turbofans have a higher Isp than PDE's, but the Isp of a PDE is greater than a mixed flow turbofan beginning around Mach 3. Theoretically you could build a VTOL PDE, but the shock waves from the engines might reflect off the ground during liftoff and damage the aircraft. But it would still be fun to try.
emb8 3 years ago