UK government invests in Sabre air-breathing rocket engine • Hacker News Board

Re: UK government invests in Sabre air-breathing rocket engine

#51

Post by northernmonkey » Thu, Jul 18, 2013, 6:42 PM UTC

voicereason wrote: post #45

ris wrote: post #38

Earlier quoted context omitted.

1. Everyone's a socialist, so using it as a pejorative doesn't really work. 2. There aren't enough "welfare claimants" in this country to really have a big influence on anything themselves. The vast (vast) majority of people claiming benefits are hard working people who do 40 hour weeks but still don't earn enough to support their family, so they claim Working Tax Credits. This was Thatcher's doing, by the way.

I should have remembered how Reddit this place has become. No idea what you mean by 1. I, along with about 50% of the UK is not a socialist. > The vast (vast) majority of people claiming benefits are hard working people who do 40 hour weeks but still don't earn enough to support their family, so they claim Working Tax Credits. Somehow they still seem to manage to afford the big flat screen TV, iPhone, xBox etc though…

> Somehow they still seem to manage to afford the big flat screen TV, iPhone, xBox etc though don't they. Funny that...

You're not serious? Are you?

Re: UK government invests in Sabre air-breathing rocket engine

#52

Post by Retric » Thu, Jul 18, 2013, 6:56 PM UTC

benl wrote: post #39

speeder wrote: post #13

Whoa, this is really awesome! For those that don't know, airbreathing engines are MUCH MORE efficient than conventional rocket engines. Not only in terms of weight saved from not having to lug around too much O2, but also because of the way it works inherently. I decided to make a space game once, with real world stuff on it, and settled for the Triton engine for my game spaceship, I did lots of research about rocket…

Are they really more efficient, for real world uses? The way I understand it, the argument goes something like this. To reach orbit you need to accelerate to very high speeds (Mach 25). To avoid crazy drag losses you therefore want to get out of the atmosphere as quickly as possible. So being able to use oxygen from the air on your way up is a marginal gain at best, and almost certainly not worth the extra complexity…

The end product from a hydrogen fueled rocket is H2O. Of which oxygen represents 88.8% of the weight so there is a lot of weight savings available to make up for the increased drag and a more complex engine design. Also of note you need to accelerate not just the ship and cargo but also all that unspent fuel so weight savings tend to multiply.

An air breathing rocket that hit's Mach 5+ means on the order of 30% less fuel and less structure to support that fuel. Which not only allows for more cargo but significantly more redundancy and a much higher structural safety margins.

Re: UK government invests in Sabre air-breathing rocket engine

#53

Post by DuskStar » Thu, Jul 18, 2013, 7:16 PM UTC

venomsnake wrote: post #34

DuskStar wrote: post #32

Earlier quoted context omitted.

As far as I can tell, the production version will use LH2 instead of Liquid Helium to cool the incoming air. (after which the Helium will be burned for thrust, no need to cool it back down) It's a similar to how most rocket engine nozzles are cooled.

You mean Hydrogen will be burned? Noble gases have hard time reacting. Except xenon with fluoride and nitrogen but you want to be away when these bonds break.

Ow, that's a bad mistake. Yeah, the Hydrogen fuel will both be used to cool the incoming air and burned for thrust.

Looking back at that comment - how did I make that many typos?!?

Re: UK government invests in Sabre air-breathing rocket engine

#54

Post by venomsnake » Thu, Jul 18, 2013, 7:31 PM UTC

arethuza wrote: post #41

venomsnake wrote: post #17

I am a bit skeptical of any technology that uses helium. We just don't have viable ways to obtain reliably enough of the stuff reliably.

Well, there is an expensive plant in France that will be manufacturing helium from raw materials ;-) http://www.iter.org/

Nuclear fusion has always been 10 years away. Lets hope that they will succeed this time.

Re: UK government invests in Sabre air-breathing rocket engine

#55

Post by 3327 » Thu, Jul 18, 2013, 8:23 PM UTC

JonnieCache wrote: post #30

3327 wrote: post #11

The Brits are good engineers, and, compared to American juggernaut companies, specially in the defense and aerospace area, they manage to make innovation with very little. The US military spent millions all through the 1960's upto the late 1980's for a successful VTOL aircraft. Along came the brits with fractions of the budget with a great product the Harrier GR-1. There are some great arguments here, specially the s…

>If the government doesn't take the risk, long term innovation would be very difficult. What I'm wondering is, if the taxpayers have to take all the risk and spend all the R&D money out of our own pockets, why don't we get to keep all the profits as well? I thought innovation was the role of heroic figures who eat risk for breakfast? I thought the massive, economy-distorting pay packages were justified by all that ri…

You are absolutely right. I am no expert in IP or government affairs but I would imagine that stakes in the project become an issue and even though a fully working "final" product say version 1.0 for production might be ready, the investment necessary for production of such parts are massive.

Second to that is the know how and expertise in precision manufacturing for such products that require a high degree of reliability.

In addition to this continues R&D and investing must be done for problems and improvements.

In summary I guess the people "get" their "profits" in the form of an army/navy/space marines equipped with the latest air breathing rocket engine.

Re: UK government invests in Sabre air-breathing rocket engine

#56

Post by 3327 » Thu, Jul 18, 2013, 8:27 PM UTC

arethuza wrote: post #16

3327 wrote: post #11

The Brits are good engineers, and, compared to American juggernaut companies, specially in the defense and aerospace area, they manage to make innovation with very little. The US military spent millions all through the 1960's upto the late 1980's for a successful VTOL aircraft. Along came the brits with fractions of the budget with a great product the Harrier GR-1. There are some great arguments here, specially the s…

Also the TSR-2 - which was a fantastic aircraft design: http://en.wikipedia.org/wiki/BAC_TSR-2 "All modern aircraft have four dimensions: span, length, height and politics. TSR-2 simply got the first three right."

wow what a beauty !

Re: UK government invests in Sabre air-breathing rocket engine

#57

Post by VladRussian2 » Thu, Jul 18, 2013, 8:53 PM UTC

simcop2387 wrote: post #49

speeder wrote: post #13

Whoa, this is really awesome! For those that don't know, airbreathing engines are MUCH MORE efficient than conventional rocket engines. Not only in terms of weight saved from not having to lug around too much O2, but also because of the way it works inherently. I decided to make a space game once, with real world stuff on it, and settled for the Triton engine for my game spaceship, I did lots of research about rocket…

If you want to play with space games that'll let you do that check out Kerbal Space Program. Might still be on sale on steam. If they can get it off the ground this could easily make things so much easier to get into LEO, since the main engines wouldn't have to carry around half the equation it'll mean much higher thrust to weight ratios, which means cheaper, and then you could have a much smaller craft increase it's…

>since the main engines wouldn't have to carry around half the equation it'll mean much higher thrust to weight ratios

on the other side you need energy to wastefully slow down with respect to the aircraft frame (i.e. provide delta-v to) 80% of the outside air - nitrogen - you scooped. Engines without slow down of the air mass - scramjets - are different beasts and have their own issues).

Thus you have choice - carry with you and speed up 1 lb of O2 to the speed of 5 Mach or slow down from 5 Mach (slow down is the same energy consuming action as speed up) 4 lb of nitrogen and 1 lb oxygen of the outside air.

Re: UK government invests in Sabre air-breathing rocket engine

#58

Post by shabble » Thu, Jul 18, 2013, 11:02 PM UTC

venomsnake wrote: post #54

arethuza wrote: post #41

Earlier quoted context omitted.

Well, there is an expensive plant in France that will be manufacturing helium from raw materials ;-) http://www.iter.org/

Nuclear fusion has always been 10 years away. Lets hope that they will succeed this time.

The fusion itself is (afaik) essentially a solved problem. The trick is extracting net energy from it, since you use a lot in generating the plasma, massive magnetic fields to keep it contained, etc.

But if you just cared about the byproducts, I think that's a much easier problem.

Probably still 10 years though :)

Re: UK government invests in Sabre air-breathing rocket engine

#59

Post by jpeg_hero » Fri, Jul 19, 2013, 1:09 AM UTC

The british are cute.

that test rig looked like something the North Koreans would put together.

this is no where near being a "real program"

Re: UK government invests in Sabre air-breathing rocket engine

#60

Post by moocowduckquack » Fri, Jul 19, 2013, 1:12 AM UTC

benl wrote: post #39

speeder wrote: post #13

Whoa, this is really awesome! For those that don't know, airbreathing engines are MUCH MORE efficient than conventional rocket engines. Not only in terms of weight saved from not having to lug around too much O2, but also because of the way it works inherently. I decided to make a space game once, with real world stuff on it, and settled for the Triton engine for my game spaceship, I did lots of research about rocket…

Are they really more efficient, for real world uses? The way I understand it, the argument goes something like this. To reach orbit you need to accelerate to very high speeds (Mach 25). To avoid crazy drag losses you therefore want to get out of the atmosphere as quickly as possible. So being able to use oxygen from the air on your way up is a marginal gain at best, and almost certainly not worth the extra complexity…

I think you may have it back to front. To avoid crazy drag losses you cruise the lower atmosphere, then kick to high speed once into much thinner air.