Advances in Aircraft Engine Design

[HTV-3X]

Hello yall,

The main purpose of this thread is discuss interesting upcoming military aircraft engines(mainly fixed wing/turbofan). I cant seem to remember the names but there were two very interesting proposals and both have a wiki page. IIRC one of them was actually a Lock-Mart design strangely enough. Does anyone know what Im talking about?

Other than that, what is the experts opinion on how fighter aircrafts engines will look for the next 40-50 years? What will be the next major changes to turbofans in the upcoming years, specifically for supersonic applications?

 

[Ricey]

For me the biggest development in engine technology is the new SABRE engine it allows normal flight with the possibility of rocket powered flight into space, it is possible to cruise at Mach 5 albeit with different configurations.

Although it is early in it's development i think it has all the potential to change the industry.

Reaction Engines Limited

 

[RobWilliams]

I'm a big fan of the SABRE engine, it uses oxygen in the atmosphere to burn with hydrogen and uses onboard liquid hydrogen when it exits the atmosphere.

I learnt a bit about it at uni for my thermodynamics module, the heat exhanger to be exact, it cools air from 1000 degrees C down to -150 degrees C in less than 1/100th of a second displacing 0.4GW of heat energy.

In the case of the SABRE engine there are two uses for heat exchangers. The first use is to cool the incoming air (which becomes very hot at high speed) so that it can be compressed to the pressure required for it to enter the rocket combustion chamber whilst concurrently heating helium, which is used to drive the engine machinery. We call the heat exchanger on the Sabre engine a Pre-cooler.
Location of the Precooler in the SABRE engine (shown in blue).

The second use is to cool the hot helium using the cold liquid hydrogen fuel, but this uses more conventional heat exchanger technology.

The team at REL has found ways to produce heat exchangers light enough to be viable for the first time in a flying engine. REL has also pioneered solutions to the other practical problems in this application, such as the control of frost formation (where the water in the atmosphere freezes in the heat exchanger, icing it up).

Reaction Engines Ltd - SABRE: How it works

 

[Ricey]

I'm a big fan of the SABRE engine, it uses oxygen in the atmosphere to burn with hydrogen and uses onboard liquid hydrogen when it exits the atmosphere.

I learnt a bit about it at uni for my thermodynamics module, the heat exhanger to be exact, it cools air from 1000 degrees C down to -150 degrees C in less than 1/100th of a second displacing 0.4GW of heat energy.



Reaction Engines Ltd - SABRE: How it works

Wow that is impressive, i have heard that the European space agency is also on board which is great not only for Europe but engineering in the UK on the whole very promising.

What kind of implications would this have if the technology is perfected and used on military aircraft? Would this give the aircraft the ability to strike from space?

 

[RobWilliams]

I would imagine so, i'm fairly sure the SABRE engine forms the engine component of the Skylon commercial passenger aircraft concept which the company is pushing to develop with Government and private funding (personally I think it could be criminal for the Government not to bring up the cash).

It's an impressive aircraft, the idea is it takes off from a conventional runway and exits the atmosphere then returns and lands on a conventional runway & the current concept would supposedly have a 'payload' of 15,000kg.

In a really basic way - i.e my perspective - it doesn't seem impossible that such an aircraft could become some kind of Mach 5.5 bomber that would probably hop in and out of space (similar to the old HyperSoar US concept) for long range missions. side note: i'm not very up on the potential of actually striking for space so i've no idea.But it would probably be an incredibly expensive (although fascinating) concept and the way things are looking is that systems of that nature are due to become unmanned.

 

[PCShogun]

In a really basic way - i.e my perspective - it doesn't seem impossible that such an aircraft could become some kind of Mach 5.5 bomber that would probably hop in and out of space (similar to the old HyperSoar US concept) for long range missions.

Actually, I was thinking the same thing after reading the article. While the idea of mounting independent CONVENTIONAL warheads on a ballistic missile would be politically and economically dangerous, the reusable ability of a reusable, re-try capable aircraft could be useful for hitting areas that are beyond range from current bases and if political issues prevent overflights of sovereign territory.

Just how high does ones airspace extend if you were to launch such a raid using an exospheric craft? Is it the Kármán line or further?

 

[HTV-3X]

Wow, thats a helluva heat exchanger. Thanks yall for showing me the SABRE. I had never seen that one before. That is definitely a world changing technology. Not to mention an aircraft(bomber/reconnaissance/etc) outside the atmosphere presents a huge challenge to SAMs military-wise.

I finally remembered the engine/missile though, its the Lockheed RATTLRS. There is, unsurprisingly, not much material out there on it though. Apparently it is powered by a YJ102R turbojet. Does anyone have anything on how the engine works, and how it is capable of such speeds with a turbojet? Possibly a turbo ramjet or maybe something more sophisticated akin to a J58?

The other interesting one is the Rolls Royce ADVENT. I would think this technology would be incorporated quite soon on aircraft, or some other variant of a variable cycle engine.

One more thing, I recently came upon the MBDA Perseus missile. Apparently it is powered by a ramjet along a "continuous wave detonation engine". Can anyone elaborate on how it works? Obviously one can deduce that it detonates the fuel-air mixture instead of deflagrating, similar to a pulse detonation engine..? But other than that, does anyone know anything else about it? I would imagine exhaust velocity to be quite high in comparison to conventional jet engines, and hence gives the capability of very high vehicle velocity in the atmosphere.

Thanks

 

[RobWilliams]

http://ftp.rta.nato.int/public//PubFullText/RTO/EN/RTO-EN-AVT-150///EN-AVT-150-08.pdf

Here's a very long & tedious NATO article about the continuous detonation wave engine, I would give you a brief overview but it's far too early & i'm on my holidays from uni so not in the best frame of mind to look through it

 

[RobWilliams]

The UK Govt has coughed up £60million to build a full scale prototype of Reaction Engines Ltd SABRE engine.

19,000mph 'spaceplane' gets Government funding to spark UK space race - Telegraph

Government to spend £60m on revolutionary Sabre rocket engine that will be used on spaceplane Skylon - Science - News - The Independent

The Government will spend £60 million on a revolutionary new rocket engine that can send astronauts into orbit and accelerate aircraft to five times the speed of sound, a minister confirmed.

...

Reaction Engines are now hoping to run flights carrying 15 tonnes of cargo to space stations by 2022.

Spaceplanes can operate as aircrafts within Earth's atmosphere, as well as functioning as a space craft when in space. Only rocket powered aircrafts have so far managed to reach space.

Skylon could be potentially viewed as a competitor to Sir Richard Branson's Virgin Galactic business, in which people can experience six minutes of weightlessness during a sub-orbital spaceflights.

Test flights for the spaceplane are initially being scheduled for 2019. The unpiloted vehicle will be able to reach speeds of more than 19,000 miles an hour, cutting the journey time from London to Australia to approximately four hours.

Interesting times ahead, hopefully it doesn't wither and die like some other UK major projects. Although it's a bit early to be forecasting dates for the aircraft considering the major challenges ahead like key technologies currently needing development.

 

[StobieWan]

I think they're being a bit optimistic if they're hoping to see a working platform of any sort by 2019 - a working *engine* maybe...

Fingers crossed, as it'd be a significant step forward *understatement*...

 

[My2Cents]

I'm a big fan of the SABRE engine, it uses oxygen in the atmosphere to burn with hydrogen and uses onboard liquid hydrogen when it exits the atmosphere.

I learnt a bit about it at uni for my thermodynamics module, the heat exhanger to be exact, it cools air from 1000 degrees C down to -150 degrees C in less than 1/100th of a second displacing 0.4GW of heat energy.

If I read the article correctly they are cooling the air by using it to boil the H2 fuel.

Doesn't say anything about the mass flows or expect thrust in each mode.