Talk:Pulse detonation engine

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Let's get some pictures in here

There's a great deal of information on this subject, somewhere. I don't know enough to make the necessary changes, but yeah this needs some pictures, and an organizational cleanup wouldn't hurt. - SloverA 12:34, 2 November 2005 (UTC)

This page needs serious wiki-fying, and it was subject to Digging today. 70.35.222.158 01:34, 4 May 2006 (UTC)

[edit] Dan Brown

This type of propulsion is also discussed in Dan Brown's novel 'Deception Point'. The air craft in question is an Aurora model.

Dan Brown is incapable of describing well-documented technology accurately, so it's completely mad to give him any sort of credence when it comes to experimental or hypothetical technology. His statement that "all technology desribed in this novel exists" should be considered as part of the novel - i.e. just as fictional as the rest of it.

[edit] Needs sources

I'm pretty sure that the text is overstating the efficiency win of PDE's. I did once see a list of specific impulses that were thought to be achieveable with PDE, and they weren't that good in quite a lot of cases, but I don't have a reference handy.

In any case, there's no citations at all. That's bad.WolfKeeper 16:59, 3 September 2006 (UTC)

The NASA website is error 404. I think its been removed. I'll take out the link, feel free to reverse it if I'm wrong.

Yes. The efficiency of PDE is greatly overestimated. People are missing that the system efficiency and overall efficiency consist of many factors.

There are burn efficiency (how much fuel burns well), fuel energy density (oxidizer drops it), thermodynamic efficiency (how much heat turns into pressure), propulsive efficiency (how close to perfect is the exhaust velocity), plus engine drag and specific thrust. These are independent components of any propulsive system efficiency, which are balanced in its design.

Layering of these efficiencies produces, in the end, the overall efficiency and then less well defined system efficiency (accounting for drag and weight of the engine). There are no "more efficient" or "less efficient" engines, the key parameters produce different results for any application, i.e. depending on airspeed, altitude and the aircraft, different engines become most efficient. Even different parameters can have radically different influence, i.e. higher specific impulse (of the exhaust) gives nearly linear increase in the efficiency of a rocket, but a decrease in the efficiency of a turbofan. Though turbofans now more commonly use fuel specific impulse, which is determines in regards to fuel alone rather than the entire volume of accelerated air.

PDE have better burn efficiency than any other engine, but that's it. Unlike turbofans, they don't accelerate bypass air, just what is used for the detonation, which leads to very limited working mass. As a result, such engine produces a lot of energy', but most of that energy is not converted into thrust.

For instance, accelerating 2,000m^3 of air in a high-bypass turbofan to 100m/s produces the same thrust as accelerating 200m^3 to 1,000m/s in a non-bypass engine, i.e. PDE, yet requires 10 times less energy.

PDE can compete (likely with advantage) and should be compared with ramjets in efficiency, but not turbofans.

Of course, at high Mach numbers, where turbofans are simply impossible or impractical, PDE enter the actual competition, with ramjets, scramjets, ramrockets, LACE, et cetera. There it is to be seen whether high weight of the engine (to survive detonation forces) will be compensated by better burn efficiency. CP/M ^comm |Wikipedia Neutrality Project| 16:39, 7 January 2008 (UTC)

Here are some references that I have not looked over but may have some use. I'll see if I can get a picture for the article some time soon.

Yungster, S. and Perkins, H.D., “Multiple-Cycle Simulation of Pulse Detonation Engine Ejector,” AIAA 2002-3630, October 2002.
Kailasanath, K., “Recent Developments in the Research on Pulse Detonation Engines,” AIAA Journal, Vol. 41, No. 2, 2003, pp. 145-159.
Bussing, T. and Pappas, G., “An Introduction to Pulse Detonation Engines,” AIAA 94-0263, January 1994.
Takuma, E. and Fujiwara, T., “A Simplified Analysis on a Pulse Detonation Engine Model,” Trans. Japan Soc. Aero. Space Sci. Vol. 44, No. 146, 2002.
Hekiri, Haider, "Parametric Cycle Analysis for Pulse Detonation Engines," Master's Thesis, Department of Mechanical and Aerospace Engineering, The University of Texas at Arlington, Arlington, TX, 2005.
Panicker, P.K., Wilson, D.R., and Lu, F.K., "Operational Issues Affecting the Practical Implemenatation of Pulse Detonation Engines," AIAA-2006-7959, 14th AIAA/AHI Space Planes and Hypersonic Systems and Technologies Conference, Nov. 6-9, 2006, Canberra, Australia.

EMBaero (talk) 18:11, 7 January 2008 (UTC)EMBaero

The efficiency of a detonation engine is far greater than that produced by the simple deflagration of fuel thus the specific impulse of the engine tends to be greater tat that produced by ram/turbo jet. I belive this is made clearin the article. Neucleon

I've explained that above. The burn efficiency is greater, i.e. less fuel is left unburned. Not "far" greater, since normal turbine already has great burn efficiency, but PDE does produce more heat. However, PDE doesn't utilize that heat as well as a turbofan does. CP/M ^comm |Wikipedia Neutrality Project| 12:09, 2 May 2008 (UTC)

[edit] First flight

FWIW, the first flight of the Rutan/AFRL PDE Longeze took place at Mojave Airport today. 71.108.80.39 (talk) 03:36, 1 February 2008 (UTC)

I've been able to confirm from another source that this is all correct. Pictures and videos will be released soon. EMBaero (talk) 16:16, 6 February 2008 (UTC)EMBaero