DARPA/Boeing X-51A WaveRider
- Thread starter flateric
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What I'm wondering is if anyone 'gets' the issue that scramjets don't appear to be ready for flight testing yet?
I haven't seen anywhere where anyone has pointed out that the "Duel-Mode-Ram/Scram-Jet" never got out of "first-gear" and went beyond ramjet operation. Ramjets are good up to around Mach-6 and everything I've seen says you need to hit Mach-7+ to get supersonic flow through the "scramjet" for operation with a DMRJ motor.
I understand WHY they have to call this a "success" but I'm not seeing anything that really shows scramjets are ready for prime time.
Randy
I haven't seen anywhere where anyone has pointed out that the "Duel-Mode-Ram/Scram-Jet" never got out of "first-gear" and went beyond ramjet operation. Ramjets are good up to around Mach-6 and everything I've seen says you need to hit Mach-7+ to get supersonic flow through the "scramjet" for operation with a DMRJ motor.
I understand WHY they have to call this a "success" but I'm not seeing anything that really shows scramjets are ready for prime time.
Randy
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RanulfC said:
On the one hand I agree BUT you won't ever get "out of first gear" without flight testing hardware. I wouldn't call this past flight a success either (unless they actually had supersonic flow through the engine) as it didn't even go as fast as ASALM which was a plain old ramjet.
RanulfC said:
Hyper-X Mach 10 (9.8) flight operated in pure scramjet mode. HiFIRE-2 successfully transitioned from dual-mode operation to scramjet operation at the higher Mach portion of it's flight trajectory. The physics are known. It's mainly a thermal-structural engineering and controls exercise for the most part, which still isn't trivial.
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sferrin said:
As far as I know, flying faster than ASALM was not a test objective. The primary objective of the program was to flight test a hydrocarbon fueled scramjet.
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Damn near every press release (until they started trying to fly it anyway) was saying Mach 6. It never even came close to that. Nor have I seen anywhere claiming they had pure supersonic combustion.quellish said:
sferrin said:
It was NEVER intended to run as a pure scramjet. Even the H2 fueled Hyper-X ran dual mode at Mach 7. One would be foolish to try to run an HC fueled engine otherwise at these lower Mach #s at decent fuelling levels. The original Aussie HySHOT ran pure scramjet mode even H2 fueled because it only ran an equivalence ratio way below unity.
shockonlip
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sferrin said:
A dual mode scramjet running in ramjet mode is a very different thing than how a ramjet does it.
The end result of subsonic combustion is similar, but how you do it in a scramjet without the two
physical throats of a ramjet (inlet throat and nozzle throat) is very different, and a successful
achievement of that is significant!
shockonlip
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sferrin said:
It doesn't matter!
Because that's not the key question here dude!
It's your key question, and you think it might have been
the program's secret goal, but I don't know, and I am
impressed by what they did anyway.
Plus I haven't seen any details yet.
Not sure they're ever going to publish any.
Personally, I am quite happy that a DM scramjet got some acceleration
at such a low Mach number. That's more significant to me.
Back in the old days there was a lot of question about that.
And the DMR patent filed in 1963 as a classified patent (not granted
in unclassified world until the late 1960's or so) was proof of how
important that capability was. So this is a big question to me and
I am quite happy with what they did.
sferrin said:
That is a a very simplistic question of a very complicated flow process. Was some part of the combustion process supersonic? Most assuredly yes. How much, that takes data. If you don't understand how complicated a question you have really posed, might I suggest you take a look at Thermodynamic Analysis of Dual-Mode Scramjet Engine Operation and Performance by Riggins, TackettTaylor and Auslender, AIAA Paper 2006-805. http://hdl.handle.net/2060/20070000536
Abstract:
Recent analytical advances in understanding the performance continuum (the thermodynamic spectrum) for air-breathing engines based on fundamental second-law considerations have clarified scramjet and ramjet operation, performance, and characteristics. Second-law based analysis is extended specifically in this work to clarify and describe the performance characteristics for dual-mode scramjet operation in the mid-speed range of flight Mach 4 to 7. This is done by a fundamental investigation of the complex but predictable interplay between heat release and irreversibilities in such an engine; results demonstrate the flow and performance character of the dual mode regime and of dual mode transition behavior. Both analytical and computational (multi-dimensional CFD) studies of sample dual-mode flow-fields are performed in order to demonstrate the second-law capability and performance and operability issues. The impact of the dual-mode regime is found to be characterized by decreasing overall irreversibility with increasing heat release, within the operability limits of the system.
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From AFRL website:
Posted this here because it sounds like the X-51A but as they don't mention it by name (it is a fairly well known project at this point) I ask the question is this something different?
........... it is envisioned this midterm concept will have two major system level demonstrations; first a flight test of a long range high speed cruise missile with the ability to cruise at high mach numbers over extended ranges using advanced guidance and warheads. The second flight test will demonstrate the increased capability to cruise at higher mach numbers using a full suite of advanced technologies..............
http://www.eglin.af.mil/library/factsheets/factsheet.asp?id=16674
Posted this here because it sounds like the X-51A but as they don't mention it by name (it is a fairly well known project at this point) I ask the question is this something different?
........... it is envisioned this midterm concept will have two major system level demonstrations; first a flight test of a long range high speed cruise missile with the ability to cruise at high mach numbers over extended ranges using advanced guidance and warheads. The second flight test will demonstrate the increased capability to cruise at higher mach numbers using a full suite of advanced technologies..............
http://www.eglin.af.mil/library/factsheets/factsheet.asp?id=16674
dark sidius
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I think this is very difficult to say where is realy the ram/scram technology, because of white and black programs, since more of a decade there is a lot of concepts and programs. Surely a derivative of the X-51 will be in the long range strike family in a near futur, the concept of the X-51 work and the speed of mach 5 is a pretty good speed for a weapon, very difficult to shoot an object with a movement capability and mach 5 speed.
bobbymike said:
Probably, but the whole this article is really about the development of the munitions required for such a system. The HSSW (High Speed Strike Weapon) program is the touted "weaponization" of "an X-51ish" type system. However, given the last FBO post in regard to that is on hold at the moment, probably due to issues associated with trying to get a new start in the budget under sequestration.
If you look at the ISP vs Mach characteristics of such a system, dual-mode operation provides higher ISP than pure scramjet operation at a given Mach where the curves overlap. From this standpoint you want want to run dual-mode as long as possible. Dual-mode also tend to have the harshest overall pressure-temperature loads internally so running here provides the tougher test from a thermal-structural perspective. One reason to possibly transition to pure scramjet mode prior to where this begets better superior ISP compared to dual-mode is to alleviate overall thermal-structural loads somewhat.RanulfC said:
ISP vs Mach plot added 2013-05-15:
Attachments
Ok, now that makes it make more sense. I'd gotten the impression from all the media it was supposed to transition all the way up to full scramjet operation AND "speeds" (Mach-7 or so) which was part of the confusion.DSE said:
Thanks all...
Randy
Hypersonic Weapons Could Hit Battlefield by 2025 at Space.com
High-Speed Strike Weapon To Build On X-51 Flight at Aviationweek.com (subscription required)
...snip
Now, as the business of data analysis begins, hypersonic planners are turning to what comes next. Although
the X-51A success marks a first step to the potential use of hypersonic propulsion for long-range
reconnaissance, transport and even the first air-breathing stage of a space-access system, the near-term
application will be a missile. Initial follow-on steps will therefore be guided primarily by the requirements of
the Air Force's high-speed weapon development road map and support of the High Speed Strike Weapon
(HSSW), which is expected to be demonstrated at a baseline level around 2020. Theoretically, given this
timescale, such a weapon could be available by the mid-2020s.
... snip
On reaching the launch point south of the Channel Islands and northwest of San Nicholas island, the X-51A was dropped at Mach 0.8. The Atacms ignited and propelled the entire 25-ft.-long stack—including the booster, inter-stage and X-51A cruiser—for 29 sec. until it reached 63,000 ft. and Mach 4.9. The cruiser separated and coasted to Mach 4.8 before the scramjet was started using ethylene. The scramjet then transitioned to JP-7 hydrocarbon fuel, successfully overcoming the point at which the second flight failed in June 2011, when “we unstarted the engine and we lost control of inlet dynamics,” says Brink. The X-51A flew for another 210 sec. under scramjet power, climbing to 64,000 ft. with a constant dynamic pressure (q) trajectory of 2,200-2,350 lb. per square foot. Peak acceleration was over 0.2g, notes Brink.
The vehicle accelerated to Mach 5.1 from Mach 4.8 and was still accelerating “when the tank ran dry,” says
Vogel. “We staged the fuel in flight and were halfway through the second staging and going well when we ran
out of fuel,” Brink adds. The initial start sequence involves spraying fuel toward the aft end of the combustor
to ensure the shock train from the combusting fuel-air mix is not pushed out of the inlet, causing an “unstart.”
As the speed builds, the fuel is injected further forward to match the changing pressure profile in the inlet and
to generate a greater rise in thrust. This had not been possible with the first flight, which was cut short when
the vehicle suffered a nozzle leak 65 sec. into the flight.
With the May 1 flight, “we were able to not only have the initial spray sequence, but in flight but we saw
signs of acceleration out of the vehicle when we staged it. That was to me the one little check-mark we didn't
get out of the first flight,” says Brink.
The X-51A was originally aimed at testing in excess of Mach 6, but none of them exceeded Mach 5.1. Brink
says early in the flight-test program , “we had a real long discussion of flight time versus the Mach 6 number,
and the consensus was it was more important to show we could control the engine acceleration and fly it on
out, run it dry and control it at hypersonic speed . I'm not saying we shot for 5.1. We thought it might be in the
mid-Mach 5 range, but we found changes to inlet geometry [which was changed to a stiffer columbium-based
alloy] made the wedge much thicker. Plus there were changes to cowling to incorporate the fourth engine. So
we knew we had added drag counts.”
Following engine shutdown, the unpowered vehicle was commanded to perform various “parameter
identification” maneuvers to characterize its aerodynamic handling and controllability. Three sets of data
were collected at decreasing Mach numbers as part of evaluations which will help pave the way for future
hypersonic testing and see “what it takes to contain and safely contain these vehicles,” says Jorris. This
testing takes place during the unpowered phase of the flight because “we understood the engine parameters.
Now we have to understand the vehicle itself, so with the engine off we can isolate the pure aerodynamic
phenomenon.” The vehicle's response to specific pitch, roll and yaw inputs will be compared to pre-test
predictions made by NASA Langley.
...snip
High-Speed Strike Weapon To Build On X-51 Flight at Aviationweek.com (subscription required)
...snip
Now, as the business of data analysis begins, hypersonic planners are turning to what comes next. Although
the X-51A success marks a first step to the potential use of hypersonic propulsion for long-range
reconnaissance, transport and even the first air-breathing stage of a space-access system, the near-term
application will be a missile. Initial follow-on steps will therefore be guided primarily by the requirements of
the Air Force's high-speed weapon development road map and support of the High Speed Strike Weapon
(HSSW), which is expected to be demonstrated at a baseline level around 2020. Theoretically, given this
timescale, such a weapon could be available by the mid-2020s.
... snip
On reaching the launch point south of the Channel Islands and northwest of San Nicholas island, the X-51A was dropped at Mach 0.8. The Atacms ignited and propelled the entire 25-ft.-long stack—including the booster, inter-stage and X-51A cruiser—for 29 sec. until it reached 63,000 ft. and Mach 4.9. The cruiser separated and coasted to Mach 4.8 before the scramjet was started using ethylene. The scramjet then transitioned to JP-7 hydrocarbon fuel, successfully overcoming the point at which the second flight failed in June 2011, when “we unstarted the engine and we lost control of inlet dynamics,” says Brink. The X-51A flew for another 210 sec. under scramjet power, climbing to 64,000 ft. with a constant dynamic pressure (q) trajectory of 2,200-2,350 lb. per square foot. Peak acceleration was over 0.2g, notes Brink.
The vehicle accelerated to Mach 5.1 from Mach 4.8 and was still accelerating “when the tank ran dry,” says
Vogel. “We staged the fuel in flight and were halfway through the second staging and going well when we ran
out of fuel,” Brink adds. The initial start sequence involves spraying fuel toward the aft end of the combustor
to ensure the shock train from the combusting fuel-air mix is not pushed out of the inlet, causing an “unstart.”
As the speed builds, the fuel is injected further forward to match the changing pressure profile in the inlet and
to generate a greater rise in thrust. This had not been possible with the first flight, which was cut short when
the vehicle suffered a nozzle leak 65 sec. into the flight.
With the May 1 flight, “we were able to not only have the initial spray sequence, but in flight but we saw
signs of acceleration out of the vehicle when we staged it. That was to me the one little check-mark we didn't
get out of the first flight,” says Brink.
The X-51A was originally aimed at testing in excess of Mach 6, but none of them exceeded Mach 5.1. Brink
says early in the flight-test program , “we had a real long discussion of flight time versus the Mach 6 number,
and the consensus was it was more important to show we could control the engine acceleration and fly it on
out, run it dry and control it at hypersonic speed . I'm not saying we shot for 5.1. We thought it might be in the
mid-Mach 5 range, but we found changes to inlet geometry [which was changed to a stiffer columbium-based
alloy] made the wedge much thicker. Plus there were changes to cowling to incorporate the fourth engine. So
we knew we had added drag counts.”
Following engine shutdown, the unpowered vehicle was commanded to perform various “parameter
identification” maneuvers to characterize its aerodynamic handling and controllability. Three sets of data
were collected at decreasing Mach numbers as part of evaluations which will help pave the way for future
hypersonic testing and see “what it takes to contain and safely contain these vehicles,” says Jorris. This
testing takes place during the unpowered phase of the flight because “we understood the engine parameters.
Now we have to understand the vehicle itself, so with the engine off we can isolate the pure aerodynamic
phenomenon.” The vehicle's response to specific pitch, roll and yaw inputs will be compared to pre-test
predictions made by NASA Langley.
...snip
sferrin said:
I'm not an expert on hysonics, but surely one must draw distinctions between individual programs and the applicability of their respective (most likely very much interchangeable) technologies, right? I'm not going to argue that things may not have been inefficient before. But to boil down past frustrations into a list of acronyms can also be a starting point in finding commonalities and ultimately operational results. What's been especially baffling to me (reading hysonics related discussions here) is that there seem to be precious few individuals who actually have (/had) a good overall command of the field - so one would expect that organizing and seeing through programs should've just flowed kinda organically from that alone? I'm just thinking that this indicates that certain technological confluences required for truly practical hysonics may not have existed before and thus exploratory programs have over promised by the way of natural excitement and optimism. It will be pretty strange when it happens though, usually articles marvel at the speeds and reduced travel times alone but Earth's atmosphere also becomes a fairly constricted operating environment past M5 for any air breathing craft.
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UpForce said:
It's not that complicated. Basically I'm saying there have been numerious prior programs, taken to various stages, that promised the world. None have delivered. Thus I am not holding my breath that this one will be any different.
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From the Designation-Systems.net Missile Scrapbook:
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DSE said:
Hmmm, yes and no. HyTech started in 1995:
http://www.globalsecurity.org/military/systems/munitions/hytech.htm
In reading closer it looks more like HyTech was a modern "BumbleBee" without the flight test articles. Then the X-51 built on that. Where hyTech wasn't a specific missile/vehicle it shouldn't have been on my list in the first place. (Just for comparison we went from the Whittle W.1 to the J58 in a similar amount of time.)
sferrin said:
The engine lines and initial fuelling schedule were developed under HyTech. Note much propulsion flowpath development was done prior to fully addressing the fuel-cooled thermal-structural problem in multiple test articles of increasing complexity. GDE-1 tested at GASL, GDE-2, X-1 and finally X-2 the flight qualification engine system all at the LaRC 8-Ft HTT.
As far as RATTLRS go the problem is the turbine doesn't really exist.
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DSE said:
"The turbine doesn't really exist?" That'll be a surprise to a former coworker of mine who worked on the one Williams International was building. Here's an ancient (probably late 80's/early 90s) ancestor to the YJ102. (Yes, I know the YJ102 was a Liberty Works product. )
"Expendable Turbine Engine. This demonstrator engine ran at temperatures over 1000 degreesF beyond the state of the art. This capability will let future missiles cruise at supersonic speeds without afterburners."
(No, the fire doesn't mean it has an afterburner. That's straight out of the turbine section.)
Downloaded from the AFRL site years ago.
shockonlip
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DSE said:
Thanks for posting this!
Sounds like a great success!
I wish we could develop these sooner!
They may be wanting to run these things in just ramjet mode even!
Seems easier and more mission flexible than building a ramjet!
sferrin said:DSE said:
"The turbine doesn't really exist?" That'll be a surprise to a former coworker of mine who worked on the one Williams International was building. Here's an ancient (probably late 80's/early 90s) ancestor to the YJ102. (Yes, I know the YJ102 was a Liberty Works product. )
"Expendable Turbine Engine. This demonstrator engine ran at temperatures over 1000 degreesF beyond the state of the art. This capability will let future missiles cruise at supersonic speeds without afterburners."
(No, the fire doesn't mean it has an afterburner. That's straight out of the turbine section.)
Downloaded from the AFRL site years ago.
As I just mentioned in the Blackswift thread I guess I incorrectly remembered the the upgraded version(s) which were slated to be used in the MoTr program and then later the NASA GRC CCE. No slights to anyone intended.
sferrin said:"The turbine doesn't really exist?" That'll be a surprise to a former coworker of mine who worked on the one Williams International was building. Here's an ancient (probably late 80's/early 90s) ancestor to the YJ102. (Yes, I know the YJ102 was a Liberty Works product. )
"Expendable Turbine Engine. This demonstrator engine ran at temperatures over 1000 degreesF beyond the state of the art. This capability will let future missiles cruise at supersonic speeds without afterburners."
(No, the fire doesn't mean it has an afterburner. That's straight out of the turbine section.)
Downloaded from the AFRL site years ago.
Hmmm, had some time to try to do some checking. Was this the initial set of tests? I'm having a hard time finding any reference to the second set of planned high Mach tests in T-3 at AEDC.
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No idea. The only information I have is the blurb which is in the quotes and an ancient PM or post from a reliable member at KeyPub years ago. I'll see if I can dig it up.
edit: I spent about as much time as I'm willing to with no luck. A poster by the name of "turboshaft" or somesuch worked in the business and explained that the engine in the photo was an ancestor to the engine(s) tested for RATTLRS. Wish I'd kept it because it was very interesting information. :-[ On the plus side I did stumble up on this:
http://www.nap.edu/catalog.php?record_id=11780
Found it but I think he elaborated in a PM. (Wished he frequented this board. )
"
Originally Posted by sferrin turboshaft might know more about it
You tryin' to get me fired? :diablo:
There were a few details publicly released on the engine in the late '90s, but most of this has disappeared following the renewed interest in high-speed strike. The Popular Mechanics article from earlier this year gave a fairly generous amount of public domain insight, including images of the YJ102R from which a rough impression of the engine's architecture can be inferred, and is worth a read for those interested in the program. Other stats released earlier in the project include the engine's length (approx. 4ft) and width (1 ft). Some data on the JETEC prototypes (XTL 16 & XTL 17) is also public realm, including their Fn/Wa achievements.
Much of this tech was developed in the late '80s and has been waiting for a suitable application. High operating temps are key to the engine's performance, and advances in metallurgy and cooling have played a key role.
The similarity to the J58 (axial-flow, single-stage) results from the similar operating environments, though none of the J58 team were involved in the J102 program.
Originally Posted by SOC Prolly explains why it appears that Lockheed is trying to turn an SR-71 nacelle into a missileLockMart's already been down that path with the 'alternative' D-21 studies.
A D-21 cutaway actually gives a fairly representative impression of the newer project's airflow, though you'll have to work out for yourself where the payload sits.
Originally Posted by Lightndattic Will this spawn a new age of very light supersonic general aviation aircraft?I think you'll be lucky to ever see Aerion fly, let alone a M3+ SSBJ. Handover $3M of greenbacks and content yourself with a Javelin for now. "
edit: I spent about as much time as I'm willing to with no luck. A poster by the name of "turboshaft" or somesuch worked in the business and explained that the engine in the photo was an ancestor to the engine(s) tested for RATTLRS. Wish I'd kept it because it was very interesting information. :-[ On the plus side I did stumble up on this:
http://www.nap.edu/catalog.php?record_id=11780
Found it but I think he elaborated in a PM. (Wished he frequented this board.
)"
You tryin' to get me fired? :diablo:
There were a few details publicly released on the engine in the late '90s, but most of this has disappeared following the renewed interest in high-speed strike. The Popular Mechanics article from earlier this year gave a fairly generous amount of public domain insight, including images of the YJ102R from which a rough impression of the engine's architecture can be inferred, and is worth a read for those interested in the program. Other stats released earlier in the project include the engine's length (approx. 4ft) and width (1 ft). Some data on the JETEC prototypes (XTL 16 & XTL 17) is also public realm, including their Fn/Wa achievements.
Much of this tech was developed in the late '80s and has been waiting for a suitable application. High operating temps are key to the engine's performance, and advances in metallurgy and cooling have played a key role.
The similarity to the J58 (axial-flow, single-stage) results from the similar operating environments, though none of the J58 team were involved in the J102 program.
A D-21 cutaway actually gives a fairly representative impression of the newer project's airflow, though you'll have to work out for yourself where the payload sits.
shockonlip
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And then there is this, from just recently:
GE Aviation Demonstrates Highest Core Temperatures In Aviation History
February 8, 2013
http://www.geaviation.com/press/military/military_20130208.html
EVENDALE, OHIO - GE Aviation completed testing its engine core for the ADaptive Versatile ENgine Technology (ADVENT) program with the U.S. Air Force Research Laboratory on February 6, 2013, achieving the highest combination of compressor and turbine temperatures ever recorded in aviation history ...
The ADVENT program is scheduled to conclude this year with a full engine test. GE will continue to mature the ADVENT technologies through the Air Force's Adaptive Engine Technology Development (AETD) program, which will conclude in 2016 following fan rig testing and a core engine test. ...
the GE ADVENT core achieved the highest combination of compressor and turbine temperatures ever achieved in the aviation industry. ...
Unlike fixed cycle engine architectures powering today's aircraft, variable cycle architectures are designed to operate efficiently in conditions across the entire flight envelope, including subsonic and supersonic speeds. GE's adaptive cycle design includes a third stream of air that can be utilized for maximum fuel efficiency and provides thermal management advantages to a conventional engine.
The ADVENT engine is GE Aviation's most recent development program to successfully demonstrate the variable cycle architecture. Following initial studies by Gerhard Neumann in the 1960s, GE's YJ101 was the first full engine to demonstrate variable cycle capabilities in 1976. GE built on the YJ101 experience to produce the YF120 variable cycle engine for the Advanced Tactical Fighter project, which set the world supercruise record in 1990.
The ADVENT and AETD variable cycle engines are improving on the YF120 design while integrating technologies developed through GE Aviation's $600 million investment in commercial engine programs, such as high pressure compressors and lightweight CMCs in the high- and low-pressure turbines that result in reduced engine weight and minimize the need for cooling. The ADVENT engine will be GE's highest overall pressure ratio military engine, resulting in a significant fuel consumption improvement compared to today's engines.
GE Aviation Demonstrates Highest Core Temperatures In Aviation History
February 8, 2013
http://www.geaviation.com/press/military/military_20130208.html
EVENDALE, OHIO - GE Aviation completed testing its engine core for the ADaptive Versatile ENgine Technology (ADVENT) program with the U.S. Air Force Research Laboratory on February 6, 2013, achieving the highest combination of compressor and turbine temperatures ever recorded in aviation history ...
The ADVENT program is scheduled to conclude this year with a full engine test. GE will continue to mature the ADVENT technologies through the Air Force's Adaptive Engine Technology Development (AETD) program, which will conclude in 2016 following fan rig testing and a core engine test. ...
the GE ADVENT core achieved the highest combination of compressor and turbine temperatures ever achieved in the aviation industry. ...
Unlike fixed cycle engine architectures powering today's aircraft, variable cycle architectures are designed to operate efficiently in conditions across the entire flight envelope, including subsonic and supersonic speeds. GE's adaptive cycle design includes a third stream of air that can be utilized for maximum fuel efficiency and provides thermal management advantages to a conventional engine.
The ADVENT engine is GE Aviation's most recent development program to successfully demonstrate the variable cycle architecture. Following initial studies by Gerhard Neumann in the 1960s, GE's YJ101 was the first full engine to demonstrate variable cycle capabilities in 1976. GE built on the YJ101 experience to produce the YF120 variable cycle engine for the Advanced Tactical Fighter project, which set the world supercruise record in 1990.
The ADVENT and AETD variable cycle engines are improving on the YF120 design while integrating technologies developed through GE Aviation's $600 million investment in commercial engine programs, such as high pressure compressors and lightweight CMCs in the high- and low-pressure turbines that result in reduced engine weight and minimize the need for cooling. The ADVENT engine will be GE's highest overall pressure ratio military engine, resulting in a significant fuel consumption improvement compared to today's engines.
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"
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA463123 page 18 Hmmm, that doesn't sound like failure. ???
AFRL completed XTL17/1 supersonic demonstrator engine testing at the Allison Advanced
Development Company/Rolls-Royce Corporation test facility (Indianapolis, Indiana).
During subsequent performance testing, the XTL17/1 expendable turbine engine achieved
a specific thrust 87% higher than the baseline defined for this engine class in the Integrated
High-Performance Turbine Engine Technology (IHPTET) program.
The XTL17/1 is part of the Joint Expendable Turbine Engine Concept portion of the IHPTET
program, demonstrating expendable and limited-life engine technologies for applications
such as cruise missiles. Demonstrations such as those involving the XTL17/1 provide the
warfighter with low-risk technology transition, resulting in a high level of readiness and increased safety and performance.
This engine’s specific thrust level is the highest ever produced by an expendable turbine engine, marking another first for the
IHPTET program."http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA463123 page 18 Hmmm, that doesn't sound like failure. ???
sferrin said:
Doesn't sound like a Mach 3+ turbine either. I can find no reference to any test above Mach 2ish. There was technology development after that, but no final proof of the pudding which I can find. Funny we're on opposite sides of the discussion here for a change.
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Wow, I don't know how I missed this thread, but I never knew the YJ101 was a variable cycle engine. Why didn't they use that feature in the F404? Cost? Complexity?
I love that pic of the high temp turbine. I had no idea they were getting so hot now. Are they using special fuels?
I love that pic of the high temp turbine. I had no idea they were getting so hot now. Are they using special fuels?
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bring_it_on
I really should change my personal text
- Joined
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An expected evolution, of the efforts so far. We should be headed towards more "operationally relevant" spending.
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