You are not logged in.
I stumbled on this:
https://www.rt.com/news/357337-new-rocket-engine-test/
Quote:
The current liquid fuel engines used by rockets to get to space have reached their maximum capabilities, according to the FPI. Instead, a pulse-detonation engine that uses high thermodynamic efficiency will allow spacecraft to reach previously unattainable performance.
It would also result in additional workload for rockets and the reduction of cost for orbital deliveries.
I got a sense that the US had run a similar smaller engine on a plane, but this is quote "The first for rockets".
The idea apparently was born in the Soviet Union 70 years ago?
I have the sense that this will require a long period of development to be put to work.
I posted this here not to do some poodle jumping, but because I am interested in the views of people who are here who have better capabilities with sensing what is real and what is bogus, and what the catches are.
Last edited by Void (2016-08-27 23:09:08)
Done.
Online
Void:
I worked with air-breathing pulse detonation around 25 years ago. There are two really serious problems: peak explosion pressures to be contained are very high (requiring heavy hardware), and (2) the vibration associated with the pulsed explosions is not really survivable for human occupants, or most types of equipment.
It was only considered for missile propulsion, and did not get beyond experimental test. There are only a very limited class of fuels that can be made to work: very modest molecular weight gases like propane, methane, maybe napthalene (if already vaporized). Kerosene does not work. Nor does gasoline. Hydrogen will, but only if already vaporized before it reaches the engine.
If you do this as a rocket, you aggravate the explosion pressure problem, and the nonsurvivable vibration problem, because the released energy per unit volume is even higher with oxygen than with air (and only if introduced as a gas, not a liquid).
But you do not get away from the detonable-fuel problem: only light gaseous fuels will detonate. Kerosene or gasoline are simply not going to work. I have my doubts about liquid methane or liquid hydrogen, unless you pre-vaporize them and feed them as gases to the engine. That costs both weight and complexity. Not to mention volume.
GW
ps -- been gone for a week traveling on vacation. Just now getting around to looking at these forums.
Last edited by GW Johnson (2016-08-28 18:09:53)
GW Johnson
McGregor, Texas
"There is nothing as expensive as a dead crew, especially one dead from a bad management decision"
Offline
Thanks GW Johnson.
It looked like it was a long way from being mastered, so you have confirmed that.
It looks like mastering re-use of hardware is the best route to lower cost launches, not what was presented in my post.
Done.
Online
Hi Void:
There was some sort of pulse-detonation flight test vehicle, or vehicles, flown from Groom Lake, Nevada. This (these?) thing(s?) produced the pearls-on-a-string contrail and a very odd rumbling sound, as seen and heard by many civilian observers. This was in the late 1980's and early 1990's, if memory serves.
It is only rumor, but one of these was supposedly piloted by a man. It is said the vibrations broke all the teeth out of his mouth. I put very little stock in such rumors, but it is not beyond the pale that a manned flight was attempted. I've heard of no such things being observed since the 1990's, though.
The attraction of the pulse detonation concept as an airbreather was static thrust capability plus speed capability to about Mach 5. That makes it potentially attractive as self-boosting missile propulsion. For short-range battlefield applications, the far-simpler solid rocket is by far the better choice, however. The airbreathers become "worth it" at medium (many dozens to a few hundreds of miles) to long (thousands of miles) ranges.
In that airbreathing embodiment, think of it as a simple pulsejet that uses full shock detonation combustion, instead of the ordinary deflagration combustion of the ordinary pulsejet. Both develop static and flying thrust, it's just that the energy release per unit volume is orders of magnitude higher in full detonation. This shows up as the combustion wave speed: feet/sec for deflagration, miles/sec for detonation.
GW
Last edited by GW Johnson (2016-08-29 09:56:00)
GW Johnson
McGregor, Texas
"There is nothing as expensive as a dead crew, especially one dead from a bad management decision"
Offline