Scramjet engine development

[PeterAlt]

I remember back in the late 80's, NASA was working on development of the scramjet engine as part of the cancelled X-30 spaceplane. The scramjet engine would have been the stage that takes hypersonic aircrafts into suborbital space. The aircraft would have lifted into flight on a traditional runway using traditional jet engines, ramjets would kick in to get it to hypersonic speeds. Then the scramjet would fire up to get it into suborbital space. Finally, onboard rock engines would fire to propel it to LEO. This was sold as low cost access to space that would lead to a space shuttle successor.

When the X-30 was cancelled, scramjet development continued for some time, finding its way into other X-plane programs and even into secret programs that have remained classified till this day. At one point, Australia did some scramjet R&D of it's own.

It has been rumored that the classified Aurora spyplane uses/used scramjet propulsion. It is also public knowledge that a top secret DARPA program started after 9/11 was supposed to have scramjet engines. I believe the X-43 program tested scramjet engines in flight a few years ago as well. That is all the development history of scramjet I know.

My speculation is that scramjet engines are currently being used in classified military aircraft programs, such as Aurora or that other program I don't know the name of that was started after 9/11.

What ever happened to the X-43 program? I've never seen any where news of it's cancellation or any news of it's current activity. Why would NASA continue scramjet development if the military supposedly already has it? And if the military already has it, why not let NASA use it for spaceplane development?

Can anyone please fill in the missing pieces?

Thanks

[Downix]

Aurora was rumored to be using a pulse-detonation jet engine, not a scramjet.  Very different technology.

The X-43 was launched ages ago:


From 2004.

Followed on by the X-51 programme:



Launched last year.  The X-51 holds the record for the longest Scramjet flights, at 140 seconds.

[rusty]

...
My speculation is that scramjet engines are currently being used in classified military aircraft programs, such as Aurora or that other program I don't know the name of that was started after 9/11.

What ever happened to the X-43 program? I've never seen any where news of it's cancellation or any news of it's current activity. Why would NASA continue scramjet development if the military supposedly already has it? And if the military already has it, why not let NASA use it for spaceplane development?

Can anyone please fill in the missing pieces?

Thanks

Scramjets can be used for high-mach testing and possibly skip flight, but it's better to go ballistic above the troposphere than work through it to reach orbit. A few military scramjet programs:
155mm Munition
http://www.atk.com/capabilities_defense/cs_ms_w_hs_vlrm-ab.asp
SAM
http://www.atk.com/capabilities_defense/cs_ms_w_hs_fastt.asp
Cruise Missile
http://www.atk.com/capabilities_defense/cs_ms_w_hs_hssw.asp

[Danny Dot]

The X-51 didn't run as long as planned.  It probably failed due to over heating.  High temperatures are a major problem and limit them to Mach 10 - maybe lower.  Orbit is Mach 25, so you need a rocket to get from Mach 10 to Mach 25.

[PeterAlt]

The X-51 didn't run as long as planned.  It probably failed due to over heating.  High temperatures are a major problem and limit them to Mach 10 - maybe lower.  Orbit is Mach 25, so you need a rocket to get from Mach 10 to Mach 25.

So, is this the issue that needs to be solved before NASA develops a prototype scramjet spaceplane?

[Jim]

So, is this the issue that needs to be solved before NASA develops a prototype scramjet spaceplane?

Why would it be NASA?

[e of pi]

The X-51 didn't run as long as planned.  It probably failed due to over heating.  High temperatures are a major problem and limit them to Mach 10 - maybe lower.  Orbit is Mach 25, so you need a rocket to get from Mach 10 to Mach 25.

My local AIAA student section had one of the team in, and he spoke about the failure and their analysis. A seal between the actively cooled engine section (via fuel, like a regenerative nozzle) and the rest of the nozzle (which was part of the airframe and passively cooled) failed due to a manufacturing difficulty, so hot exhaust gases leaked into the rest of the airframe, and started eating it from the inside and eventually lead to loss of data and vehicle breakup. He says they reworked the seal, and the next flights should be able to avoid the issue.

The heat protection scheme was apparently pretty good, it uses some of the same Boeing Lightweight Ablator materials that they plan to use on CST-100. Now, there's a difference between operating at Mach 6, and Mach 10, or Mach 12, and that would mean challenges but that wasn't the source of failure on the X-51A.

[mlorrey]

The X-51 didn't run as long as planned.  It probably failed due to over heating.  High temperatures are a major problem and limit them to Mach 10 - maybe lower.  Orbit is Mach 25, so you need a rocket to get from Mach 10 to Mach 25.

My local AIAA student section had one of the team in, and he spoke about the failure and their analysis. A seal between the actively cooled engine section (via fuel, like a regenerative nozzle) and the rest of the nozzle (which was part of the airframe and passively cooled) failed due to a manufacturing difficulty, so hot exhaust gases leaked into the rest of the airframe, and started eating it from the inside and eventually lead to loss of data and vehicle breakup. He says they reworked the seal, and the next flights should be able to avoid the issue.

The heat protection scheme was apparently pretty good, it uses some of the same Boeing Lightweight Ablator materials that they plan to use on CST-100. Now, there's a difference between operating at Mach 6, and Mach 10, or Mach 12, and that would mean challenges but that wasn't the source of failure on the X-51A.

Ah this is good info. I had feared that the loss of thrust was due to coking of the fuel coolant/reformer system with carbon deposits.