Author Topic: Will scramjet planes ever take off?  (Read 15706 times)

Offline 8900

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Will scramjet planes ever take off?
« on: 11/12/2009 12:23 PM »
Anyone have thought of this question? Why Concorde, an engineering masterpiece becomes economic disaster?

In the 1960s-70s many people predict the future of aviation industry will be supersonic, but eventually it turns out that concorde and in general supersonic passenger aviation fails terribly, and from the first commercial jet in 1950s (Comet) to the A380 of the new century, we are still travelling subsonic. The speed of passenger jet haven't change much in past half century, although the size and fuel efficiency increased significantly.
Does this implies that the prediction that scramjet and the promise of 21st century superfast intercontinental travel will eventually turn out to be the same story: cost too high, too noisy etc. and will never take off? Like the Concorde, like the Maglev, they all once offered great promises. If people can connect to the internet, use IM, read instant news feed, and hold video conference on the plane, that 1x hours they can do these things like on the ground, would they ever consider an expensive hypersonic flight over a cheap subsonic flight?
« Last Edit: 11/12/2009 12:25 PM by 8900 »

Offline William Barton

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Re: Will scramjet planes ever take off?
« Reply #1 on: 11/12/2009 12:35 PM »
There's little need for commercial travelers to get anywhere on Earth any faster than they already can. What we need is more convenient and more comfortable. What we really need (and is yet a ways off due to economic system lag) is an air transport system that runs on a passenger-irrelevant schedule. The planes follow their routes, carrying whoever is aboard, and the fleet cost/profit margin is averaged across the system. Like a 500mph busline, where you go to the airport, buy a ticket, and climb aboard the next flight. You might have to change planes alot to get to someplace far away. But you wouldn't have to buy a special, non-refundable, imaginary-discount ticket 5 months in advance. (When my father was a boy, you could actually travel by streetcar across much of the northeast US. He went from Boston to someplace in NJ [I forget where] that way one time on a lark.)

Offline grakenverb

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Re: Will scramjet planes ever take off?
« Reply #2 on: 11/12/2009 12:37 PM »
Unless a supersonic airplane can be operated as routinely and as cheaply as the current subsonic fleet, I think the answer is "no".  Perhaps there will be a market for the uber-rich to have supersonic private planes, but Joe Six Pack will be lumbering through the sky at 500 mph for the foreseeable future, IMHO.

Offline khallow

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Re: Will scramjet planes ever take off?
« Reply #3 on: 11/12/2009 07:01 PM »
There's little need for commercial travelers to get anywhere on Earth any faster than they already can.

Maybe there's little "need", but there's plenty of "want" to get there faster. India from the West coast takes something like 30 hours. Lot of people would pay more to get there a lot faster.
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Re: Will scramjet planes ever take off?
« Reply #4 on: 11/12/2009 07:24 PM »
Concorde was profitable for the for the airline (british airways) for most of it's life but was unprofitable for the company that made it. Mainly due to the 70s spike in oil costs drying up orders and the US restriction on supersonic overflights.

I used to live under the flight path and the booms never bothered me, in fact I barely heard them.

Shame really.

Offline kevin-rf

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Re: Will scramjet planes ever take off?
« Reply #5 on: 11/12/2009 07:32 PM »

The holy grail is you catch an early morning flight, have your meeting, and get home at a decent hour.

That requires a short stay at the airport, a fast flight (less than 2 hr), meetings of sufficient length, and at an acceptable price. Until you can travel from NY to India in that time span there will always be want/desire for a super/hypersonic cruiser.

The key is economics... Atlas proved back in the 1950's that you can send a payload anywhere in the world in less than 90 minutes. The problem is the cost was to high to justify using it for business trips.
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Offline 93143

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Re: Will scramjet planes ever take off?
« Reply #6 on: 11/12/2009 07:32 PM »
There's research going on in the EU.  Not strictly "scramjet", but definitely a lot faster than what we have now.

http://ec.europa.eu/research/transport/projects/article_3666_en.html

http://www.reactionengines.co.uk/lapcat.html

The Concorde was fuel-inefficient, range-limited and not all that much faster than a normal airliner.  A new vehicle that could go halfway around the world at Mach 4 or better, and still be efficient when subsonic for overflight of populated areas, would solve all these problems.  Reaction Engines figures a flight from Brussels to Sydney on their A2 would cost about 4000 Euros, and if I recall correctly that assumed a fairly expensive method of hydrogen production...

Offline mlorrey

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Re: Will scramjet planes ever take off?
« Reply #7 on: 11/13/2009 12:25 AM »
Concorde was profitable for the for the airline (british airways) for most of it's life but was unprofitable for the company that made it. Mainly due to the 70s spike in oil costs drying up orders and the US restriction on supersonic overflights.

I used to live under the flight path and the booms never bothered me, in fact I barely heard them.

Shame really.


BA found it profitable on a few limited routes that fit both the range limitations of the jet, the over water limits, and had the necessary market size  of luxury passengers willing to shell out thousands per ticket.

The plane did not meet original range specifications, and that is what greatly limited its marketability. There was a proposal for an upgraded version that would have had slightly larger wings and greater fuel capacity to make longer range flights. Would have increased the number of possible routes ten fold.

These are the little economic factors that may get overlooked in development but are make or break for the viability of the vehicle, same as happened with Shuttle, where the silica TPS' high maintenance requirements cut the possible sortie rate by 3/4 and thereby doomed the commercialization of the vehicle.
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Offline 8900

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Re: Will scramjet planes ever take off?
« Reply #8 on: 11/13/2009 10:39 AM »
Concorde was profitable for the for the airline (british airways) for most of it's life but was unprofitable for the company that made it. Mainly due to the 70s spike in oil costs drying up orders and the US restriction on supersonic overflights.

I used to live under the flight path and the booms never bothered me, in fact I barely heard them.

Shame really.


BA found it profitable on a few limited routes that fit both the range limitations of the jet, the over water limits, and had the necessary market size  of luxury passengers willing to shell out thousands per ticket.

The plane did not meet original range specifications, and that is what greatly limited its marketability. There was a proposal for an upgraded version that would have had slightly larger wings and greater fuel capacity to make longer range flights. Would have increased the number of possible routes ten fold.

These are the little economic factors that may get overlooked in development but are make or break for the viability of the vehicle, same as happened with Shuttle, where the silica TPS' high maintenance requirements cut the possible sortie rate by 3/4 and thereby doomed the commercialization of the vehicle.
It assumed hydrogen fuel, which is expensive and troublesome to handle.
Scramjet can easily reach Mach 4 with standard jet fuel, the problem is scramjet engine needs a high starting speed, how do you bridge the 0mph to starting speed is a problem unsolved (unless you use rocket, which is used in experimental flights)
« Last Edit: 11/13/2009 11:20 AM by 8900 »

Offline Downix

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Re: Will scramjet planes ever take off?
« Reply #9 on: 11/13/2009 11:04 AM »
Concorde was profitable for the for the airline (british airways) for most of it's life but was unprofitable for the company that made it. Mainly due to the 70s spike in oil costs drying up orders and the US restriction on supersonic overflights.

I used to live under the flight path and the booms never bothered me, in fact I barely heard them.

Shame really.


BA found it profitable on a few limited routes that fit both the range limitations of the jet, the over water limits, and had the necessary market size  of luxury passengers willing to shell out thousands per ticket.

The plane did not meet original range specifications, and that is what greatly limited its marketability. There was a proposal for an upgraded version that would have had slightly larger wings and greater fuel capacity to make longer range flights. Would have increased the number of possible routes ten fold.

These are the little economic factors that may get overlooked in development but are make or break for the viability of the vehicle, same as happened with Shuttle, where the silica TPS' high maintenance requirements cut the possible sortie rate by 3/4 and thereby doomed the commercialization of the vehicle.
It assumed hydrogen fuel, which is expensive and troublesome to handle.
Scramjet can easily reach Mach 4 with standard jet fuel, the problem is scramjet engine needs a high starting speed, how do you breach the 0mph to starting speed is a problem unsolved (unless you use rocket, which is used in experimental flights)
in-place solid rocket, similar to how the military gets ramjets going.
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Re: Will scramjet planes ever take off?
« Reply #10 on: 11/13/2009 07:38 PM »
...

...
It assumed hydrogen fuel, which is expensive and troublesome to handle.
Scramjet can easily reach Mach 4 with standard jet fuel, the problem is scramjet engine needs a high starting speed, how do you breach the 0mph to starting speed is a problem unsolved (unless you use rocket, which is used in experimental flights)
in-place solid rocket, similar to how the military gets ramjets going.

In-place solids? Not for commercial flights!!!
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Offline mlorrey

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Re: Will scramjet planes ever take off?
« Reply #11 on: 11/13/2009 08:40 PM »
It assumed hydrogen fuel, which is expensive and troublesome to handle.
Scramjet can easily reach Mach 4 with standard jet fuel, the problem is scramjet engine needs a high starting speed, how do you bridge the 0mph to starting speed is a problem unsolved (unless you use rocket, which is used in experimental flights)

If you have a pile of money to throw at the problem, you develop what is called a combined cycle engine. There are two types:

Rocket Based Combined Cycle (RBCC) uses a rocket engine in the core with the ram/scram jet built around it. This would use the rocket engine to reach high subsonic, transition from there to ramjet til mach 5, transition there to scramjet til mach 10-12, then back to pure rocket the rest of the way to orbit. NASA was developing this type of engine in the early oughties and was proposing a $400 million program to build a prototype test vehicle called GTX, which would have flown between 2004-2009 on suborbital test flights to Mach 15. This program was cancelled by Bush-Cheney in favor of Love And Missiles, but the engine is built in prototype form and tested in wind tunnels as well as having undergone Navier Stokes simulation.

Turbine Based Combined Cycle (TBCC) uses a turbine engine core with the ram/scramjet built around it and is speed limited to the top end speed of the scramjet. This obviously is only useful on a first stage. One of the big engine companies developed this concept in its Pyrojet project and is capable of propelling vehicles up to mach 8. They have not as yet received any nonclassified customers for this engine...

If you want to save money on developing expensive hardware like this, you can follow a proposal like my own in the link at the bottom of this message: tow launch, use ramjets up to mach 8, drop the ramjets, go the rest of the way on rocket power.

You could alternatively launch from an airfield under rocket power and air refuel like Clapp's Black Horse proposal suggests.
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Offline Danny Dot

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Re: Will scramjet planes ever take off?
« Reply #12 on: 11/13/2009 10:09 PM »
It assumed hydrogen fuel, which is expensive and troublesome to handle.
Scramjet can easily reach Mach 4 with standard jet fuel, the problem is scramjet engine needs a high starting speed, how do you bridge the 0mph to starting speed is a problem unsolved (unless you use rocket, which is used in experimental flights)

If you have a pile of money to throw at the problem, you develop what is called a combined cycle engine. There are two types:

Rocket Based Combined Cycle (RBCC) uses a rocket engine in the core with the ram/scram jet built around it. This would use the rocket engine to reach high subsonic, transition from there to ramjet til mach 5, transition there to scramjet til mach 10-12, then back to pure rocket the rest of the way to orbit. NASA was developing this type of engine in the early oughties and was proposing a $400 million program to build a prototype test vehicle called GTX, which would have flown between 2004-2009 on suborbital test flights to Mach 15. This program was cancelled by Bush-Cheney in favor of Love And Missiles, but the engine is built in prototype form and tested in wind tunnels as well as having undergone Navier Stokes simulation.

Turbine Based Combined Cycle (TBCC) uses a turbine engine core with the ram/scramjet built around it and is speed limited to the top end speed of the scramjet. This obviously is only useful on a first stage. One of the big engine companies developed this concept in its Pyrojet project and is capable of propelling vehicles up to mach 8. They have not as yet received any nonclassified customers for this engine...

If you want to save money on developing expensive hardware like this, you can follow a proposal like my own in the link at the bottom of this message: tow launch, use ramjets up to mach 8, drop the ramjets, go the rest of the way on rocket power.

You could alternatively launch from an airfield under rocket power and air refuel like Clapp's Black Horse proposal suggests.

The internal working of the combined engine will melt.  I am not even sure you could make a variable inlet that will not melt at the very, very high heat. 

Also scram jets are VERY fuel inefficient.  I saw a chart on them vs. turbo and ram jets.  They are not that much better than a rocket that has to carry its own oxidizer.   Fuel cost was a big problem with Concord.  I think it paid its way on operating cost, but never paid back development cost (I am not sure on this).   Maintenance cost was out of sight also.

I think a military based cruise missile is all scram jets are going to be good for.  Maybe not even good for that, but even then it is worth the money spend so far on just developing the concept.

And I believe a ram jet needs a strong shock wave at the inlet to run.  This makes them something like Mach 3 to run.  I might be wrong on this, maybe someone can find us a link.

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Offline isa_guy

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Re: Will scramjet planes ever take off?
« Reply #13 on: 11/13/2009 10:36 PM »
Mlorrey may i correct you? First. since when ramjets works up to mach 10, they will melt down at around mach 6 (thats why the supersonic ramjets were invented). Second the  GTX program was an Air-augmented rocket and not a rbcc (as i know it) engine if you want to see a real rbcc engine check out the x-43 program and a specially the x-43b with its ISTAR engine http://gltrs.grc.nasa.gov/reports/2005/TM-2005-213432.pdf plus there is no any rocket mode after the scramjet engine ignited ( thats why nasp failed) and the rocket mode that comes before the scramjet are just a little rocket injectors that turn on the ramjet mode . As for the tbcc engine you are right but the tbcc engine is much more efficient than the rbcc engine and more durable ( but more complex) . for more info see here http://gltrs.grc.nasa.gov/reports/2001/TM-2001-210564.pdf and of course here http://www.wslfweb.org/docs/usg/afsabhyper.PDF plus you may look at Darpa and Afrl latest work on the first stage for tbcc engine PROJECT VULCAN that aims to combine a turbine engine with a cvc or pde and than combine it with ramjet/scramjet engine to create a tbcc engine http://www.darpa.mil/tto/solicit/BAA08-53/VULCAN_Industry_Day_Presentations.pdf. and if you have a time check out those studies  http://gltrs.grc.nasa.gov/reports/2003/TM-2003-212612.pdf , http://www.nianet.org/workshops/pdfs/NASA-NIA_ETO_Workshop_RJ_Litchford.pdf  it seems that MHD Augmented Propulsion could give us a real SSTO. correct me if i am wrong :) .
« Last Edit: 11/13/2009 10:39 PM by isa_guy »

Offline colbourne

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Re: Will scramjet planes ever take off?
« Reply #14 on: 11/14/2009 02:51 AM »
If the requirement is to have meetings with people on the otherside of the world I am afraid that the Concorde has been replaced by things like the Internet with video phone capability.

To travel efficiently around the world I reckon we could use rotating tethers where a large object in orbit around the world has a long tether (500km) and this rotates so that it is travelling in  the opposite direction to the orbit when  near the Earth.
It is proposed that orbital speed could be maintained by solar power and reacting against the Earths magnetic field.
Boarding would be difficult (but possible ) depending on the speed of the tether. Possibly Concorde could be used for this.
Freight might also be carried where shorter tethers could be used and G-forces are not such a concern.

Offline mlorrey

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Re: Will scramjet planes ever take off?
« Reply #15 on: 11/14/2009 08:31 AM »
Mlorrey may i correct you? First. since when ramjets works up to mach 10, they will melt down at around mach 6 (thats why the supersonic ramjets were invented).

A crude BOMARC ramjet will melt down around mach 6. Ever seen its construction? I have. Not impressive.

I've researched this topic area for over a decade now, I know every nook and cranny in the technology.

At around mach 6, ramjets start entering a zone of increasing compression heating that rises faster than thrust does with speed. Creates a bit of a diminishing returns curve. Unless, of course, you do something about the compression heating, which is where MIPCC comes in.

Quote

Second the  GTX program was an Air-augmented rocket and not a rbcc (as i know it) engine

No, it was not.
For instance, here is a study titled "Performance Evaluation of the NASA GTX RBCC Flowpath"
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20010092480_2001150040.pdf

Pretty sure NASA knows what sort of engines they put on their GTX.... Air augmented rocket is merely the first subsonic phase of operation of the engine at launch, as it is with any RBCC.

Quote


 if you want to see a real rbcc engine check out the x-43 program and a specially the x-43b with its ISTAR engine http://gltrs.grc.nasa.gov/reports/2005/TM-2005-213432.pdf plus there is no any rocket mode after the scramjet engine ignited ( thats why nasp failed) and the rocket mode that comes before the scramjet are just a little rocket injectors that turn on the ramjet mode .

X-43 was purely a scram jet, not an RBCC, which required a Pegasus to get up to scramjet speed. X-43b is an entirely different bird, and yes, it does also use an RBCC design. The b never flew, they just tested the engine in the test cell specced in the pdf you cited. That engine was known as the 'Strutjet'. One of the problems with its design, as with the X-43 scramjet, is the box cross sectional design, causes a lot of losses in the corners that detracts from the performance potential of the engine type.

The GTX RBCC uses a circular cross section so doesn't encounter these loss issues.

Quote

As for the tbcc engine you are right but the tbcc engine is much more efficient than the rbcc engine and more durable ( but more complex) . for more info see here http://gltrs.grc.nasa.gov/reports/2001/TM-2001-210564.pdf and of course here http://www.wslfweb.org/docs/usg/afsabhyper.PDF


The above really aren't technical research reports on the technology, and are pretty out of date.

Quote
plus you may look at Darpa and Afrl latest work on the first stage for tbcc engine PROJECT VULCAN that aims to combine a turbine engine with a cvc or pde and than combine it with ramjet/scramjet engine to create a tbcc engine http://www.darpa.mil/tto/solicit/BAA08-53/VULCAN_Industry_Day_Presentations.pdf.

Turboramjet and turbofans already get higher Isp than PDE and are limited to the same sub-Mach4 speed range.

You are trying to replace a machine gun with a blunderbuss.

Quote
and if you have a time check out those studies  http://gltrs.grc.nasa.gov/reports/2003/TM-2003-212612.pdf , http://www.nianet.org/workshops/pdfs/NASA-NIA_ETO_Workshop_RJ_Litchford.pdf  it seems that MHD Augmented Propulsion could give us a real SSTO. correct me if i am wrong :) .

I am extremely skeptical of MHD, people do not appreciate the step conversion efficiency losses. MHD may be useful for power generation for vehicle systems in a hypersonic military craft. All this is adding immense levels of complexity into the process that will bury any such program in NASP levels of epic fail. Once you get to space MHD is useless for on board power generation so then you need ANOTHER system then... more complexity, more fail.

If MHD was so easy, VASIMR wouldn't be so hard.
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Offline mlorrey

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Re: Will scramjet planes ever take off?
« Reply #16 on: 11/14/2009 08:39 AM »
The internal working of the combined engine will melt.  I am not even sure you could make a variable inlet that will not melt at the very, very high heat. 

Also scram jets are VERY fuel inefficient.  I saw a chart on them vs. turbo and ram jets.  They are not that much better than a rocket that has to carry its own oxidizer.   Fuel cost was a big problem with Concord.  I think it paid its way on operating cost, but never paid back development cost (I am not sure on this).   Maintenance cost was out of sight also.

I think a military based cruise missile is all scram jets are going to be good for.  Maybe not even good for that, but even then it is worth the money spend so far on just developing the concept.

And I believe a ram jet needs a strong shock wave at the inlet to run.  This makes them something like Mach 3 to run.  I might be wrong on this, maybe someone can find us a link.

Danny Deger

Sorry, you are behind the convo and very wrong. Standard ramjets have flown up to mach 5.5 in flight and wind tunnel tests have taken them higher. Ramjets do NOT require a strong shock wave at all. They can run at any speed above 0.

Scramjets are NOT very fuel inefficient, their Isp is many times higher than a rocket engine using the same fuel. JP-7 scramjets will range from 900-1200 seconds (over 2000 sec for LH2), while the highest kerolox rocket engine gets 350 secs. Scramjets ARE less efficient than ramjets until you start reaching mach 7, but not by much. Above that point, they are competitive til you reach a point that ramjets cant run at all.
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Offline isa_guy

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Re: Will scramjet planes ever take off?
« Reply #17 on: 11/14/2009 11:20 AM »
So why nasa cancelled the RTA study http://gltrs.grc.nasa.gov/reports/2005/TM-2005-213803.pdf (it also should  be used for darpa's falcon project and funded under air force's Histed program). and instead darpa chose to use the vulcan configuration ( cvc/pde embodied with existing turbofan such as the p&w f119 ), pluse i have never seen a turbofan that could get you to mach 4 speeds even  the blackbird engine the J58 could 'only' get you to mach 3.2  and that with a ramjet bypass system, currect me if i am wrong :).
« Last Edit: 11/14/2009 11:20 AM by isa_guy »

Offline 93143

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Re: Will scramjet planes ever take off?
« Reply #18 on: 11/14/2009 02:48 PM »
I'm pretty sure you're wrong.  The engines weren't the limiting factor on the SR-71.  Around Mach 3.6 - 3.7, the airframe would start to fail; that's why it never went faster than that.

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Re: Will scramjet planes ever take off?
« Reply #19 on: 11/14/2009 09:18 PM »
I'm pretty sure you're wrong.  The engines weren't the limiting factor on the SR-71.  Around Mach 3.6 - 3.7, the airframe would start to fail; that's why it never went faster than that.

The SR-71 is limited by both engine and structural temperature to about Mach 3.6.  If it was just temp, it could dash to engine speed limit.

And next time I design a missile, I will remember I can just use a ramjet as long as I am moving.   This will save a lot on the large solid to get the engine up to start speed.

If not a shockwave to compress the air in a ramjet, what does the compression?

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Offline mlorrey

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Re: Will scramjet planes ever take off?
« Reply #20 on: 11/15/2009 12:02 AM »
I'm pretty sure you're wrong.  The engines weren't the limiting factor on the SR-71.  Around Mach 3.6 - 3.7, the airframe would start to fail; that's why it never went faster than that.

The SR-71 is limited by both engine and structural temperature to about Mach 3.6.  If it was just temp, it could dash to engine speed limit.

And next time I design a missile, I will remember I can just use a ramjet as long as I am moving.   This will save a lot on the large solid to get the engine up to start speed.

If not a shockwave to compress the air in a ramjet, what does the compression?

Danny Deger

At subsonic speeds, you are still piling up a pressure front at the head of the vehicle, but a ramjet expands the air once past the inlet to slow it down. A ramjet will normally have a compression ramp or spike at the inlet but notice that the inlet cross sectional area is significantly less than the combustion chamber cross secion. This ensures a) that combustion gasses won't want to go back out the intake, and b) once past mach 1, the combustion chamber airflow will remain subsonic while the vehicle is supersonic.
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Re: Will scramjet planes ever take off?
« Reply #21 on: 11/15/2009 12:07 AM »
I'm pretty sure you're wrong.  The engines weren't the limiting factor on the SR-71.  Around Mach 3.6 - 3.7, the airframe would start to fail; that's why it never went faster than that.

Yes that was my understanding as well, from pilots who flew them. By mach 3.5 the engines were pretty much on pure ramjet mode and could continue to accelerate if you didn't throttle them down.

Recall that when subsonic and refuelling, the aircraft's skin shrinks in size opening leaks in the tanks. Likewise, at top speed the skin is fully expanded and has the airframe in compression. Any more heating of the skin and panels would literally pop their rivets and peel off.
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Offline mlorrey

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Re: Will scramjet planes ever take off?
« Reply #22 on: 11/15/2009 12:11 AM »
So why nasa cancelled the RTA study http://gltrs.grc.nasa.gov/reports/2005/TM-2005-213803.pdf (it also should  be used for darpa's falcon project and funded under air force's Histed program). and instead darpa chose to use the vulcan configuration ( cvc/pde embodied with existing turbofan such as the p&w f119 ), pluse i have never seen a turbofan that could get you to mach 4 speeds even  the blackbird engine the J58 could 'only' get you to mach 3.2  and that with a ramjet bypass system, currect me if i am wrong :).

NASA has never let practicality be a factor in making cancellation decisions on anything. For many years their raison d'etre was not to colonize space, but to spend as much money as possible 'advancing the state of the art' but never actually doing much of anything with that state of the art.
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Offline Jim

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Re: Will scramjet planes ever take off?
« Reply #23 on: 11/15/2009 01:33 AM »
For many years their raison d'etre was not to colonize space,

Since when is that NASA's charter?
« Last Edit: 11/15/2009 01:33 AM by Jim »

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Re: Will scramjet planes ever take off?
« Reply #24 on: 11/15/2009 01:35 AM »
I'm pretty sure you're wrong.  The engines weren't the limiting factor on the SR-71.  Around Mach 3.6 - 3.7, the airframe would start to fail; that's why it never went faster than that.

Yes that was my understanding as well, from pilots who flew them. By mach 3.5 the engines were pretty much on pure ramjet mode and could continue to accelerate if you didn't throttle them down.



It was the engines and EGT was the limiting factor.

Offline mlorrey

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Re: Will scramjet planes ever take off?
« Reply #25 on: 11/15/2009 01:41 AM »
For many years their raison d'etre was not to colonize space,

Since when is that NASA's charter?

Thats the question the Augustine Commission is asking: is it or is it not the mission of NASA to lead in the goal of colonizing the moon, mars, and other locations in space? If it is not the goal, then the Augustine Commission finds no reason for NASA to pursue the Ares program.
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Re: Will scramjet planes ever take off?
« Reply #26 on: 11/15/2009 01:44 AM »

Thats the question the Augustine Commission is asking: is it or is it not the mission of NASA to lead in the goal of colonizing the moon, mars, and other locations in space? If it is not the goal, then the Augustine Commission finds no reason for NASA to pursue the Ares program.

No. Exploration and colonization are two different things
« Last Edit: 11/15/2009 01:44 AM by Jim »

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Re: Will scramjet planes ever take off?
« Reply #27 on: 11/15/2009 03:23 AM »

Thats the question the Augustine Commission is asking: is it or is it not the mission of NASA to lead in the goal of colonizing the moon, mars, and other locations in space? If it is not the goal, then the Augustine Commission finds no reason for NASA to pursue the Ares program.

No. Exploration and colonization are two different things

http://www.thespacereview.com/article/1483/1
Greason addressed—and rejected—some of the common justifications for human spaceflight, ranging from science to international cooperation to technology spinoffs. Humans can be far more effective in scientific work than robots, he noted as one example, “but that doesn’t mean you can justify the space program based on the science that it does” since other fields of research can give you “more science than the buck”.

“The trap with all of these justifications is that it’s not enough to say that if we spend money on space then we get these benefits,” he said. “If you’re justifying spending money on space because of this benefit or that benefit, you have to look not at the alternative of not doing it, you have to look at the opportunity cost: what else could you have spent that money on, and could you have gotten benefits out of that, too.”

All these things are benefits that you get as part of having a human spaceflight program, but what, then, is the key justification for it? “I knew that the reason why we go to space is because we’re going to live there someday,” he said. “We are opening a new frontier for humanity, we are creating new places and making them accessible for us. This is what the future is about.”

Greason said he was “stunned” that the rest of the committee agreed with him. “I never imagined that nine other people who are aerospace greybeards not only knew that but were willing to say that.”

And then, in a line that generated an impromptu round of applause from the Boston audience: “It’s time for the real justification for human spaceflight to come out of the closet.”

and to ensure you dont try to claim thats not in the Augustine report, voila:

"These more tangible benefits exist within a larger context. Exploration provides an opportunity to demonstrate space leadership while deeply engaging international partners; to inspire the next generation of scientists and engineers; and to shape human perceptions of our place in the universe. The Committee concluded that the ultimate goal of human exploration is to chart a path for human expansion into the solar system. This is an ambitious goal, but one worthy of U.S. leadership in concert with a broad range of international partners."
http://www.ostp.gov/galleries/press_release_files/Augustineforweb.pdf
« Last Edit: 11/15/2009 03:24 AM by mlorrey »
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Offline savuporo

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Re: Will scramjet planes ever take off?
« Reply #28 on: 11/15/2009 04:44 AM »

The holy grail is you catch an early morning flight, have your meeting, and get home at a decent hour.

That requires a short stay at the airport,
Stop right there. You can improve the flight times to silly hours, but if you have to be at airport 2 hours before, and it takes 1 hour to get out, adding an hour both to get there and back, minutes you will shave off the actual flight time will be irrelevant.

Orion - the first and only manned not-too-deep-space craft

Offline madscientist197

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Re: Will scramjet planes ever take off?
« Reply #29 on: 11/15/2009 07:22 AM »
Yes, but there are plenty of other places in the world which aren't quite so paranoid about airport security. It's essentially impossible to stop anyone with sufficient intellegence and determination (admittedly airport security does seem to have caught a fair number lacking the first ;) ).

If you can afford to fly on an ultra-expensive supersonic plane and the point of difference is that it takes less time out of your day then the carrier is going to go out of their way to intigate fast, efficient airport security. It is possible; I just think that for most (particularly budget oriented carriers) it doesn't make economic sense. You have to wait in queues because it is cheaper than using more advanced screening technology and having more personnel. For example, if people are going to be doing international travel extremely regularly it might make sense to do one-off detailed background checks in lieu of interrogating the person every time they cross the border. There would still need to be ID verification and baggage scans, but it might not require any human interaction -- just put your baggage in an scanning device and put your eye up to the retinal imager.
« Last Edit: 11/15/2009 07:25 AM by madscientist197 »
John

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Re: Will scramjet planes ever take off?
« Reply #30 on: 11/15/2009 12:21 PM »

The holy grail is you catch an early morning flight, have your meeting, and get home at a decent hour.

That requires a short stay at the airport,
Stop right there. You can improve the flight times to silly hours, but if you have to be at airport 2 hours before, and it takes 1 hour to get out, adding an hour both to get there and back, minutes you will shave off the actual flight time will be irrelevant.
That's why high speed rail has its value of survival: minimal waiting time at the terminal compared with jets

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Re: Will scramjet planes ever take off?
« Reply #31 on: 11/15/2009 03:35 PM »
On wait time at airports.  It would go much faster if they just gave everyone a knife and had us board.   And I pitty the fool that tries to light their shoes next time. 

There is no way anyone is going to take control of another plane.  People don't like to be Kamikazed into buildings on a beautiful fall day.

Serious though.  There is a good point that there is a point of diminishing returns on decreasing airline travel time due to all the time spent on the ground. 

Danny Deger
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Offline mlorrey

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Re: Will scramjet planes ever take off?
« Reply #32 on: 11/15/2009 04:16 PM »
On wait time at airports.  It would go much faster if they just gave everyone a knife and had us board.   And I pitty the fool that tries to light their shoes next time. 

There is no way anyone is going to take control of another plane.  People don't like to be Kamikazed into buildings on a beautiful fall day.

Serious though.  There is a good point that there is a point of diminishing returns on decreasing airline travel time due to all the time spent on the ground.

Well, that depends. You are going to spend all that time on the ground anyways no matter how long your flight is. If all you need to do is fly Boston to DC, I agree its a complete waste of time to go ballistic/hypersonic.

If your destination is a five hour flight away, to do a three hour business meeting, going ballistic is the difference between making it home for dinner that day to be with your kids or getting home at dinner the NEXT day. If you are someone who is a CEO/CFO/CTO/Rock Star/Supersurgeon/Power Lawyer who effectively makes $10,000 an hour, then an $50,000 ticket on a ballistic/hypersonic shuttle is a cost effective use of resources.
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Offline William Barton

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Re: Will scramjet planes ever take off?
« Reply #33 on: 11/15/2009 04:28 PM »
There's little need for commercial travelers to get anywhere on Earth any faster than they already can.

Maybe there's little "need", but there's plenty of "want" to get there faster. India from the West coast takes something like 30 hours. Lot of people would pay more to get there a lot faster.


You're talking about the difference between a commercial fleet airliner (which is what Concorde was supposed to be) and a private charter. I don't know what the prospects are for the Aerion Supersonic Business Jet coming to market and succeeding, but obviously somebody thinks there's enough "want" to sell them. Maybe we'll see.

Offline William Barton

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Re: Will scramjet planes ever take off?
« Reply #34 on: 11/15/2009 04:31 PM »
Concorde was profitable for the for the airline (british airways) for most of it's life but was unprofitable for the company that made it. Mainly due to the 70s spike in oil costs drying up orders and the US restriction on supersonic overflights.

I used to live under the flight path and the booms never bothered me, in fact I barely heard them.

Shame really.


I was working on a seismic survey near Dulles Airport in the late 1970s (to predict bedrock blasting requirements for new sewer installation). Concorde's engine noise didn't bother me, but it bothered the heck out of our geophones! My understanding is, Concorde only went supersonic over the open sea, so unless you lived on a boat, you wouldn't have heard the booms from closeby.

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Re: Will scramjet planes ever take off?
« Reply #35 on: 11/15/2009 04:37 PM »
There's little need for commercial travelers to get anywhere on Earth any faster than they already can.

Maybe there's little "need", but there's plenty of "want" to get there faster. India from the West coast takes something like 30 hours. Lot of people would pay more to get there a lot faster.


You're talking about the difference between a commercial fleet airliner (which is what Concorde was supposed to be) and a private charter. I don't know what the prospects are for the Aerion Supersonic Business Jet coming to market and succeeding, but obviously somebody thinks there's enough "want" to sell them. Maybe we'll see.

There are at any given time, depending on the economy between 800-1200 billionaires in the world these days. Such folks would use a ballistic/hypersonic vehicle on a regular basis.

There are approximately 320,000 multimillionaires in the world in 2009. All of these are potential passengers at least once, along with family members. The top 20% are in the hundreds of millions of dollars range that makes flights several times a year economically smart if they are working rich.
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Offline William Barton

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Re: Will scramjet planes ever take off?
« Reply #36 on: 11/15/2009 04:53 PM »
There's little need for commercial travelers to get anywhere on Earth any faster than they already can.

Maybe there's little "need", but there's plenty of "want" to get there faster. India from the West coast takes something like 30 hours. Lot of people would pay more to get there a lot faster.


You're talking about the difference between a commercial fleet airliner (which is what Concorde was supposed to be) and a private charter. I don't know what the prospects are for the Aerion Supersonic Business Jet coming to market and succeeding, but obviously somebody thinks there's enough "want" to sell them. Maybe we'll see.

There are at any given time, depending on the economy between 800-1200 billionaires in the world these days. Such folks would use a ballistic/hypersonic vehicle on a regular basis.

There are approximately 320,000 multimillionaires in the world in 2009. All of these are potential passengers at least once, along with family members. The top 20% are in the hundreds of millions of dollars range that makes flights several times a year economically smart if they are working rich.

It's the same reasoning that leads some to predict sales of "space yachts." The question is, how often do these people really need to travel on business? If I were that rich, would I risk my neck on a ballistic transport, or would I send 50 flunkies economy class? What kind of business does Bill Gates do that requires his personal presense? (Of course, I am someone who doesn't enjoy travel at all. If it weren't for rdp, I'd be in a different line of work.)

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Re: Will scramjet planes ever take off?
« Reply #37 on: 11/15/2009 10:04 PM »

There are at any given time, depending on the economy between 800-1200 billionaires in the world these days. Such folks would use a ballistic/hypersonic vehicle on a regular basis.

There are approximately 320,000 multimillionaires in the world in 2009. All of these are potential passengers at least once, along with family members. The top 20% are in the hundreds of millions of dollars range that makes flights several times a year economically smart if they are working rich.

It's the same reasoning that leads some to predict sales of "space yachts." The question is, how often do these people really need to travel on business? If I were that rich, would I risk my neck on a ballistic transport, or would I send 50 flunkies economy class? What kind of business does Bill Gates do that requires his personal presense? (Of course, I am someone who doesn't enjoy travel at all. If it weren't for rdp, I'd be in a different line of work.)

There are executives today who own retired supersonic fighter jets, partly for the fun, partly because they can get places faster to do business. Note you dont have to wait two hours at the airport if you own your own plane.

I doubt many private SS2's will be sold, but I can believe whatever XCOR builds after the Lynx would sell well, depending on its range. My own concept X-106 could be easily used suborbitally without the tow, launching from an airfield with the rocket engine to get the ramjet going, then turning the rocket off til you reach high speed, then use it again to boost ballistically. Wing loading on reentry is only 14 lb/sqft, so you can glide it like a Cessna 172, with less drag.

Larry Ellison is IMHO an excellent candidate for such a vehicle. He is notorious for flying his GIV into San Jose late at night to get home the same day, picks up a lot of fines for the late landings, which he pays without reservation. I think he'd pay very handsomely to get home earlier.
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Offline RanulfC

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Re: Will scramjet planes ever take off?
« Reply #38 on: 11/20/2009 04:18 PM »
On the history of the scramjet; they have been theoretically studied since soon after the first person though up the ramjet :)

It has always been "assumed" (yes I used that delibratly :) ) that ramjet engines would have issues with having to shock hypersonic (Mach-5+) incoming air down to subsonic speeds for combustion so that speeds above Mach-5 would need an engine capable of supersonic combustion. Hence SCRamJet or Supersonic Combustion Ramjet :)

Also "assumed" was that there was ONLY one fuel that could be used for supersonic combustion and that was Liquid Hydrogen.

Research into scramjets therefor had to 'wait' on the availability of LH2, then began to get it to burn (and produce thrust) at supersonic speeds.

Meanwhile research and testing along with actual real-world operations of ramjet engines showed they did NOT have an issue with hypersonic speeds and could be operated up to the limits of the matrerial strength of the engine. (Nothing "official" mind you but there is data around that indicates Mach-8 has been done at least in testing with a "standard" subsonic combustion ramjet)

Meanwhile OTHER research showed that you could actually get hydrocarbon fuels to ignite, burn and produce thrust in scramjets without resorting to overly long and 'drag-producting' ducts.
With the advent (though theoretically mentioned and studied as far back as the early '50s) of the "Inward Turning Inlet" (a good website for explaining the concept and other rocket or air breathing concepts is here:
http://books.google.com/books?id=7WStVFhkmwUC&pg=PA136&lpg=PA136&dq=inward+turning+inlet&source=bl&ots=HMntCFaOaf&sig=7MbTIlvCfOOM4VLwign9B1tfpsM&hl=en&ei=eMcGS5WdAYvysgPUg6jACQ&sa=X&oi=book_result&ct=result&resnum=9&ved=0CCsQ6AEwCA#v=onepage&q=inward%20turning%20inlet&f=false
for both ramjet and scramjet use especially the newest designs which reduces the need for heavy movable ramps systems.

An example of a simple inward turning inlet is here:
http://www.mae.virginia.edu/HyV/flighttesting.htm

Imagine a "C" turned open-side down, now it narrows down from the front towards the middle of the vehicle till it comes to the combustion section. The open 'slot' along it's length helps allow the engine to 'spill' excess pressure and achieve more effcient combustion in the combustion section. The "nozzle" area expand back out to take maximum advantage of altitude adjustment and thrust.

Now does ANY of this mean that scramjets will ever be actually PRACTICAL? I've not a clue, but my personal opinion is that they probably won't. Simply because they fill a 'niche' in propulsion that only really works at hypersonic speeds which require much more robust airframe to stand the terrific heating such speeds generate.

For travel such as has been discussed getting OUT of the atmosphere for most of the flight is MUCH easier on the airframe and in practice easier to do with skip-glide trajectories rather than having scramjets.
By 'skipping' out of the reasonable atmosphere (between 150,000ft to 200,000ft or more) the vehicle experiances much lower heat loads and can effectivly radiate the majority of that heat away in between 'skips' while maintaing 'speed' by using thrust when inside the effective atmosphere.

The skip-glide is NOT a "rollercoaster" ride of sharp up and downs but a low frequency 'gentle' motion with times between reaching appoge and the paragee of each 'skip' being on average around 10 minutes. By using a form of 'ramjet' propulsion known as "external burning" (where fuel is injected between vehicle shockware and the vehicle hull itself and combusted using the lower surface and shockwave interface as a 'virtual' ramjet) vehicle drag can be lowered dramitically and much less fuel is used than would be the case if the vehicle remained plowing through the atmosphere.

Technically I suppose "external burning" IS a scramjet of a type since the fuel would burn at supersonic speeds but by using the vehicle underside as intake, combustor, and expansion ramp combustion is much easier to achieve and the fuel has plenty of time to combust fully.

Randy
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