More info on wikipedia: SABRE Rocket Engine

He did not explain things particularly well.

He said it was a pre-cooler, it showed that it could cool air from +1000C down to -150C in 1/100 sec which is pretty amazing. And he said that this was cooling air going into the engine down to that temp...

However he never explained the problem this was solving. What temperature is air usually going into the engine? Why does it need to be cold? What happens if you don't cool it?

Just a poorly written piece, did not lay out Problem->Solution very well at all.

By the sounds of it, it's pretty amazing tech, just wish this were better at explaining it.

Space - whatever. Sydney to London in 4.5 hours - awesome!

Being able to fly from Montreal to back home in Melbourne in 1/3 the time it takes now? Where do I sign up?

I just hope this doesn't go the way of Concorde

>> ^spoco2:

He did not explain things particularly well.
He said it was a pre-cooler, it showed that it could cool air from +1000C down to -150C in 1/100 sec which is pretty amazing. And he said that this was cooling air going into the engine down to that temp...
However he never explained the problem this was solving. What temperature is air usually going into the engine? Why does it need to be cold? What happens if you don't cool it?
Just a poorly written piece, did not lay out Problem->Solution very well at all.
By the sounds of it, it's pretty amazing tech, just wish this were better at explaining it.


my guess would be cold air is denser, which means the engine can produce more thrust and is therefore more efficient. Just a hunch.

Comment hidden because you are ignoring dag.(show it anyway)

Hot!

Alright, this is totally obvious but I just couldn't help it:
http://www.youtube.com/watch?v=rLDgQg6bq7o

Technological questions aside, the economics will likely never work for scheduled flights. Concorde was scrapped because it was a money loser, not because it didn't work. I don't see anything here that suggests a ticket on this thing wouldn't be astronomically expensive.

Alan Bong or Alan Bond? Those two names have very different connotations.

Apparently adding a 1-ton 400 Megawatt air conditioner to a rocket engine improves efficiency. Who knew?

But it's just under 60% as efficient as a Boeing 747-400, so I hope this never happens.

http://en.wikipedia.org/wiki/SABRE_(rocket_engine)#Performance
http://en.wikipedia.org/wiki/Specific_impulse#Energy_efficiency

>> ^bmacs27:

Alan Bong or Alan Bond? Those two names have very different connotations.


Thanks for catching my typo. I'm sure Mr. Bong would be a lot more fun guy to hang with, though!

>> ^Ickster:

Technological questions aside, the economics will likely never work for scheduled flights. Concorde was scrapped because it was a money loser, not because it didn't work. I don't see anything here that suggests a ticket on this thing wouldn't be astronomically expensive.


Actually this is wrong. The Concorde did lose money at first, but then they did a survey asking people how much they thought a ticket from NYC to London on the Concorde would cost, and the results of the survey was that everyone thought it was more expensive than they were actually charging. So then they decided to charge a lot more for the tickets and market it as a "luxury" flight. This gimmick was successful - it became more profitable than any other division of BA.

It was retired after the famous crash while taking off in France. Even though that was it's only crash, after long investigation, and decline in first class passengers, they never brought it back.

I'm glad that many of them made it to museums, because the Concorde was a phenomenal piece of engineering.

I have no idea how well this Reaction Engine will work, but I hope to see it succeed.

This will be awesome if I ever move to London and decide to buy a summer home in Sydney.

And don't forget that the first flight with passengers after that crash, was on September 11, 2001. Not a good time for aviation or travel in general.

They must be talking about using space to get from Europe to Australia, as friction is a real bitch otherwise.

The thumbnail image for this video has been updated - thumbnail added by ZappaDanMan.

>> ^deathcow:

They must be talking about using space to get from Europe to Australia, as friction is a real bitch otherwise.

Possibly, although I think its somewhat more likely they'd just be flying at very high altitudes where the atmosphere is very thin.


From what I read on wiki it seems the engine is basically rocket/turbine hybrid. They use liquid hydrogen as fuel but instead of storing oxygen they suck it out of the air. The problem the cooling fixes seems to be related to supersonic airflow. Turbine engines need subsonic airflow to work properly so they use a ram, a cone on the front of the turbine, to slow the airflow before it enters the engine. This heats the air entering the engine up a lot, hot air takes up more space and so its difficult to get enough oxygen to the hydrogen fuel. Cooling the air after it passes over the ram lowers the air pressure and allows more air to pass through the engine. Scramjets approach this problem a different way in that they can operate with supersonic airflow, although they have the limitation of not working subsonic.

Anyway. Its quite fascinating. I don't think we'll be seeing commercial aircraft using this technology anytime soon though. I'd be pretty nervous about flying on something that is basically rocket powered. Space tourism maybe? If it can fly to high altitudes with the turbine and then switch seamlessly to using onboard oxygen it could be a much more efficient way of getting into space without using onboard oxygen the whole way up.

Oh, and RIP Concorde. I used to go to school under their flightpath out of Heathrow. 11am on Wednesdays they used to rattle the windows passing over.

All I wanna know is how this breakthrough gets me the flying car I was promised 40 years ago in Popular Mechanics.

40 years ago we still didn't fully comprehend just how dangerous we were on the ground. Texting teens buzzing along at 300mph, oh.. hell.. no.., I'll be busy setting up SAM sites in the front yard.

Commercial application is all about the intersection of increased profitability for a business and the factors people want to pay for.

Fast is a factor but only one factor. People want faster but they are also scared of fast, but likewise they'd rather flights we're cheaper, had more leg room, had better amenities etc. Businesses want to move more people at a time at less cost - especially if they are going to start paying for CO2 and increasing fuel costs.

You get so far and then improving a single factor just has diminishing returns unless you totally disrupt the whole model.

If we had videosift back when the internal combustion engine was invented, it would have been slaughtered as being too expensive and impractical compared to a horse.

"At high speeds this precooler cools the hot, ram compressed air leading to an unusually high pressure ratio within the engine. The compressed air is subsequently fed into the rocket combustion chamber where it is ignited with stored liquid hydrogen. The high pressure ratio allows the engine to continue to provide high thrust at very high speeds and altitudes. The low temperature of the air permits light alloy construction to be employed which gives a very lightweight engine — essential for reaching orbit." —WikiPedia