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Current US hypersonic weapons projects. (General)

mkellytx

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@mkellytx : I think that at 30 000lb you can fit a fighter engine and have an hybrid propulsion setup (jet/rocket/scramjet).
Then, it doesn't put aside the need for Stratolaunch to carry it around during tests or provide range for the vehicule.
@TomcatViP my read on this is not a hybrid propulsion otherwise you'd see something like an SR-72. My assumption is pure and simple a 30klb class demonstrator, with a booster that gets in hypersonic to start the SCRAM jet.
 

bobbymike

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Ten times the weight might be a different metric, but X-51 I think was ~3000lbs (not sure if that includes the booster). Seems like it might be a little light for a fighter, but then again maybe it would be a twin engined fighter. Plus we're just talking about a demonstrator engine. It seems like you could make a hypersonic fighter size aircraft with that engine; the hard part would be boosting an object of that size to effective scramjet speed. What would you even launch it off of, a Falcon 9?
X-51 was IIRC around 3000lb without the ATACMS booster, AF fact sheet says 4000lbs doesn't say if it's for the vehicle or the whole stack. Granted the last time I saw official X-51 documentation was over 12 years ago.

FWIW 30,000 lbs is an early F-16 in an A2A loadout, which is too big to fit under the wing of a BUFF. Why bring this up? One of the BUFF pilot, TPS instructor, then hypersonics guy, now retired just became the CTO at Stratolaunch, which announced it's focus is now hypersonic research. Coincidence?

If things scale up here, a 30,000 lb demonstrator would need a 10,000 lb booster if you can get the carrier up to 48-49,000 ft. The carrier can take up to a 500,000 lb payload to 35,000 ft, so a 30,000 lb demonstrator with a 20,000 lb booster is only 10% capacity. No need for something as big as an F9 first stage. Wonder if we're in for an announcement in the near future...

Edit:
Forgot to mention, Milkman (the CTO), who hated that call sign because he hated Karl Malone "The Mailman" (couldn't stand the Jazz), so he named himself "Doctor". So us crew dogs being crew dogs called him "Dr. Love" just to piss him off. Totally off topic funny aside, aside, Milkman/Doctor/Dr. Love was very heavily evolved in X-51 program even if Shotgun ended up flying the mission in the left seat...
A nice announcement would be a true air launched “strategic” strike weapon (by treaty definition greater than +5500 km)
 

Josh_TN

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@mkellytx : I think that at 30 000lb you can fit a fighter engine and have an hybrid propulsion setup (jet/rocket/scramjet).
Then, it doesn't put aside the need for Stratolaunch to carry it around during tests or provide range for the vehicule.
@TomcatViP my read on this is not a hybrid propulsion otherwise you'd see something like an SR-72. My assumption is pure and simple a 30klb class demonstrator, with a booster that gets in hypersonic to start the SCRAM jet.

It was a ground wind tunnel test, so the complications of getting the inlet speeds up to the required level in a non experimental way were not addressed.
 

mkellytx

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It was a ground wind tunnel test, so the complications of getting the inlet speeds up to the required level in a non experimental way were not addressed.
Exactly. The conditions of a tunnel very controlled and pristine compared to free flight. Free flight is more messy even for steady state activities. Next step is to repeatedly demonstrate the ability to do multiple steady state activities. Remember there are only 9 mins worth of X-51 data, that's precious little data, most of it is climbing straight ahead accelerations. Before jumping to a SR-72, it would be nice to demonstrate climbing/descending turns, level accelerations/decelerations all without unstarting the engine. Which means most important thing to demonstrate is the ability to restart an unstarted engine.

This would still very much be an X-plane, something like a SR-72 concept seams more to be a Y prefix prototype.
 

mkellytx

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@mkellytx : I think that at 30 000lb you can fit a fighter engine and have an hybrid propulsion setup (jet/rocket/scramjet).
Then, it doesn't put aside the need for Stratolaunch to carry it around during tests or provide range for the vehicule.
@TomcatViP My first reply stated what I thought was next, I didn't really adequately explain why what you suggest here isn't a likely next step. It's very easy visualize a 30,000 lb Viper and then think why off course have a proper engine, landing gear and the like. That 30,000 lb Viper will almost drain its tanks going from the runway to Mach 2 @ 50,000 ft unless you tank after you climb and after the speed run. Consider another 30,000 lb class demonstrator, the X-15 which did go to Mach 6 or could climb to over 60 miles. The X-15 was around 12,000 lbs empty, little over 31,000 lbs fully fueled, 34,000 lb with drop tanks.

Three of the four X-51's failed, the final one flew 6 minutes, program netted 9 mins of data, never made it to Mach 6. Hybrid propulsion only adds complexity, a new system integration, a new potential for failure. The fighter sized demonstrator needs to gather hours of data to make something like SR-72 potentially viable. Notice DARPA hasn't responded to LM's marking campaign and LM hasn't invested billions of IRAD to develop. Next step, reusable, able to maneuver, able to restart it's engine in flight and able to gather larger sized chunks of data. X-51 could achieve 6 mins on around a 10% fuel fraction, X-15 it was about 60% fuel+oxidizer and the isp of the engine was 140, the high flights took just over 11 min. Ideally, 20-30% fuel fraction and sustain greater than 15 mins hypersonic.

An interesting aside, the X-51 guys relied heavily on X-15 data. The Hypersonic's Director mentioned that to me in 2007 interview, they wanted me to come over but I had zero interest in a job that removed me from flight status.
 
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TomcatViP

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Hi @mkellytx :
And Merry Christmas to you & all here,

You are absolutely correct. That's why I am uncertain why they should not use Stratolaunch for range.
As you put it an air start would be more appropriate to cut fuel cost. But think that with a jet engine and rocket propulsion activated right after takeoff (similar to 1970 Mirage III with rocket booster for example), they could have more than 50000lbs of thrust with a next to 2 t/w ratio.
That's enough for roughly 50/60 000ft per minute...
It will still do for a short mission radius, but might fit the needs for something like an interceptor (if there is any - low orbit included).

Airstart under Stratolaunch:
20 min at Mach 6+ is ~1000N.M range. It should fit in any tactical force employment book (even if the return leg has to be subsonic with jet only).

Please notice that I don't deny the experimental aspect that would certainly remain here. I am not saying that it would be a fully operational aircraft (if it is!). Just that they might want a little bit more from the industry that just another X.
 
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Josh_TN

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X-51 only maintained powered scramjet flight for 210 seconds before fuel exhaustion. Presumably the rest of the flight was rocket boost and post burn out glide.
 

TomcatViP

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Well, if we stick to the arbitrary 10 time factor, 210s ~=3min
Ten time that is 30min

Hence my 20 min run at Mach 6+ for a roughly 1000N.m leg ;)
 

bring_it_on

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mkellytx

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Hi @mkellytx :
And Merry Christmas to you & all here,

You are absolutely correct. That's why I am uncertain why they should not use Stratolaunch for range.
As you put it an air start would be more appropriate to cut fuel cost. But think that with a jet engine and rocket propulsion activated right after takeoff (similar to 1970 Mirage III with rocket booster for example), they could have more than 50000lbs of thrust with a next to 2 t/w ratio.
That's enough for roughly 50/60 000ft per minute...
It will still do for a short mission radius, but might fit the needs for something like an interceptor (if there is any - low orbit included).

Airstart under Stratolaunch:
20 min at Mach 6+ is ~1000N.M range. It should fit in any tactical force employment book (even if the return leg has to be subsonic with jet only).

Please notice that I don't deny the experimental aspect that would certainly remain here. I am not saying that it would be a fully operational aircraft (if it is!). Just that they might want a little bit more from the industry that just another X.
@TomcatViP Mostly we seem to be in violent agreement. There may, however, be a lot of underlying assumptions, knowledge and experience underlying each of our preferences here that make me feel like we might be talking past each other. Given the title of the thread my read is you are looking for a solution that is most like a functioning weapons system. If that's the case, you are correct a hybrid system on a fighter sized demonstrator is closest to an ISR/strike weapons system and could be a good risk reduction for a 100,000 lb. class SR-72 type of vehicle.

Where I think you and I differ is that level of knowledge/maturity/understanding of the aerodynamics, flight dynamics, propulsion integration for airbreathing hypersonic free flight is enough to support a DoD program of record with the data available (X-43/X-51) with acceptable political, programmatic and technical risk. It can be done, the technologies without a doubt can be developed and matured. Can they be developed and matured with an acceptable political, programmatic (cost/schedule/[performance) and technical risk in a single step? No. This is my gut feel based on some interaction with the subject, interaction with some of the players and from working in DoD acquisitions for several years.

The fact that the first batch of urgent need hypersonic weapons developed are all rocket boost with various hypersonic glide/maneuver vehicles tend to verify my gut. Yes, there is funding for airbreathing weapons, however the delivery schedule for those is further to the right, that also backs up my gut on the maturity of the tech.

The political side is pretty self explanatory, look at the start and stop nature of airbreathing hypersonic programs over the last 40 years. Even the successful programs have a mixed record of success compared to the program objectives. This doesn't exactly help if you're a bright major, program officer in the Pentagon trying to get funding for your pet project. Let's not forget either the broader political environment, when X-51 was going on sequestration was all the rage, that doesn't help get funding for the next step.

The programmatic side is also pretty easy to follow. It's not that we can't solve the technical problems, it's can we solve the technical problems with a reasonable cost and schedule. This is where the challenge of integrating 3 separate propulsion technologies is a real challenge. If there are only minutes of powered hypersonic flight data, spending time and money (engineering NRE) on integrating takes away from NRE on the hypersonic problem. Not that these won't need to be done, I just believe given my experience that it's better to solve the hypersonic problem before solving the integration problem. Integration by nature isn't strictly addition, a lot of times it's more like multiplication. Now, designing a gas turbine inlet, GT, exhaust system that can operate from .6M to 3.0M requires some engineering work, it's well understood, but making it work with a ramjet that can work as a scramjet is challenging. Skip the ramjet and use a rocket to cover 3.0M to 4.9M, that adds a third system which now takes up volume and weight cutting into fuel fraction. Integrated rocket scramjet is a viable option, the challenge is coming up with a rocket to fit into the nozzle and combustion chamber that can accelerate from .8M to 4.9M. Very good for a viable weapons system, mature enough to put into a demonstrator in 3-4 years, questionable.

Rocket booster behind the hypersonic vehicle, proven and well understood. Integration here is not as big of a challenge, the demonstrator can focus only on the hypersonic scramjet simplifying the demonstrator to only integrating one propulsion system and solving the problems of free flight with only that single propulsion system. Now, before writing this reply I spent a bit of time going back through my gouge and catching up on hypersonics, Stratolaunch and a bunch of other stuff. The interesting thing I came across was that Stratolaunch is working with NG to integrate Pegasus XL. Recall, the original Pegasus first stage was the booster for X-43, so I spent some time tracking down the Pegasus XL User Guide. The stats for Pegasus XL first stage are 36,195 lb., max vacuum thrust 162,034 lbf and 69 second burn time. A bit bigger than the ATACMS booster X-51 ratio multiplied by 10, but considering Stratolaunch's published launch point is for a 500,000 lb payload launched at 35,000 ft., proportionally the booster will need more smash to cover the greater Δh and the more dense air (ρ @ 35kft = 0.3805 g/L, ρ @ 50 kft = 0.1876 g/L). The combined 30,000 lb demonstrator and first stage is just over 66,0000 lbs (T/W conveniently is 2.45 @ launch).

Finally, the challenge of finding the range space to test this thing. MGen Eichorn's presentation covers this a bit. Curiously, one of the things I vividly remember from my interview with the Director of Hypersonics was reviewing the maps of the supersonic corridors used for the YB-70 as a basis for new hypersonic corridors. There are options here that could work. Fortunately, one of the first principles of flight test is a building block approach to test points. Why do I mention this? Those 1,000 mile swath's of airspace aren't required for the early tests. Building block approach, you'll keep the first tests short, demonstrate basic controllability and ability to accelerate and turn and RTB. Pretty much existing ranges are enough to perform the early tests, if successful it sets the stage for doing longer tests.

Alright, I've written a book now, which I hate doing at risk of boring the readership. This however, is about the most succinct account I can assemble to explain what comes next for airbreathing hypersonics based upon my interactions with the field and the practitioners. Hopefully this is not too much of a bore.
 

TomcatViP

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You absolutely nailed it. Great post. Enjoyed reading it.
The delta in air density at launch would certainly influence system architecture.
Interesting also to read the synergistic approach b/w Stratolaunch and Pegasus (given they are both orbiting NG sphere of influence wouldn't that point to a separate program than the hypothetical LM one we are discussing now?)
 

mkellytx

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You absolutely nailed it. Great post. Enjoyed reading it.
The delta in air density at launch would certainly influence system architecture.
Interesting also to read the synergistic approach b/w Stratolaunch and Pegasus (given they are both orbiting NG sphere of influence wouldn't that point to a separate program than the hypothetical LM one we are discussing now?)
Stratolaunch was built by Scaled, which is owned by NG now. My read is there are two separate projects, one is for a hypersonic demonstrator, no clue who has the contract, if there is a contract or if it's something being worked in a SCIF. This is another gut feeling based on Stratolaunch changing their focus after Paul Allen passed and then hiring a hypersonic guy as their CTO. LM continues to keep SR-72 on life support looking for funding from DoD/DARPA, then again they just bought Aerojet which is building scramjets.
 
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Josh_TN

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I believe Northrop is making the scramjet engine for the Raytheon submission for the DARPA HAWC demonstrator. Supposedly it is entirely 3D printed.
 

mkellytx

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I believe Northrop is making the scramjet engine for the Raytheon submission for the DARPA HAWC demonstrator. Supposedly it is entirely 3D printed.
Thanks forgot about that one. If HAWC works as advertised then I will begin to overcome some of my previous skepticism. Hypersonics is like fusion or the economy of Brazil, "It's the future technology (economy) and always will be."
 

In_A_Dream

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Ten times the weight might be a different metric, but X-51 I think was ~3000lbs (not sure if that includes the booster). Seems like it might be a little light for a fighter, but then again maybe it would be a twin engined fighter. Plus we're just talking about a demonstrator engine. It seems like you could make a hypersonic fighter size aircraft with that engine; the hard part would be boosting an object of that size to effective scramjet speed. What would you even launch it off of, a Falcon 9?
X-51 was IIRC around 3000lb without the ATACMS booster, AF fact sheet says 4000lbs doesn't say if it's for the vehicle or the whole stack. Granted the last time I saw official X-51 documentation was over 12 years ago.

FWIW 30,000 lbs is an early F-16 in an A2A loadout, which is too big to fit under the wing of a BUFF. Why bring this up? One of the BUFF pilot, TPS instructor, then hypersonics guy, now retired just became the CTO at Stratolaunch, which announced it's focus is now hypersonic research. Coincidence?

If things scale up here, a 30,000 lb demonstrator would need a 10,000 lb booster if you can get the carrier up to 48-49,000 ft. The carrier can take up to a 500,000 lb payload to 35,000 ft, so a 30,000 lb demonstrator with a 20,000 lb booster is only 10% capacity. No need for something as big as an F9 first stage. Wonder if we're in for an announcement in the near future...

Edit:
Forgot to mention, Milkman (the CTO), who hated that call sign because he hated Karl Malone "The Mailman" (couldn't stand the Jazz), so he named himself "Doctor". So us crew dogs being crew dogs called him "Dr. Love" just to piss him off. Totally off topic funny aside, aside, Milkman/Doctor/Dr. Love was very heavily evolved in X-51 program even if Shotgun ended up flying the mission in the left seat...

And if it was a test in support of a "SR-72" platform?
 

mkellytx

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And if it was a test in support of a "SR-72" platform?
It's not that I'm outright opposed to all things SR-72, just that as part of my interview with Hypersonics back in the day I remember discussions about Blackswift, only to see it canceled several months later. So, color me skeptical if I think there should be some intermediate step before jumping straight to a SR-72 or F-22 sized demonstrator (as Skunk Works proposed at one point) with combined cycle engine.
 

Flyaway

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And if it was a test in support of a "SR-72" platform?
It's not that I'm outright opposed to all things SR-72, just that as part of my interview with Hypersonics back in the day I remember discussions about Blackswift, only to see it canceled several months later. So, color me skeptical if I think there should be some intermediate step before jumping straight to a SR-72 or F-22 sized demonstrator (as Skunk Works proposed at one point) with combined cycle engine.
I think you might be placing too much relevance on a project that to me at least seems like ancient history in comparison to things today in these kind of projects.
 

Josh_TN

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And if it was a test in support of a "SR-72" platform?
It's not that I'm outright opposed to all things SR-72, just that as part of my interview with Hypersonics back in the day I remember discussions about Blackswift, only to see it canceled several months later. So, color me skeptical if I think there should be some intermediate step before jumping straight to a SR-72 or F-22 sized demonstrator (as Skunk Works proposed at one point) with combined cycle engine.
I think you might be placing too much relevance on a project that to me seems like ancient history in comparison to things today in these kind of projects.
I think it is something all the sceptics would love to be wrong about, but the fact is the US has one successful in air scramjet test in many decades. It's possible some work is completely secret, but the slow progress of HAWC is not encouraging. Hopefully both demonstrators are flown soon.
 

In_A_Dream

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You could take one unique stance and say that public innovation is a way to mislead our adversaries & the general public.

True innovation gets a cloak, and a blank check if necessary.
 

mkellytx

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You could take one unique stance and say that public innovation is a way to mislead our adversaries & the general public.

True innovation gets a cloak, and a blank check if necessary.
Don't get your hopes up, the last hypersonic project to leave the black world was X-37.
 

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You could take one unique stance and say that public innovation is a way to mislead our adversaries & the general public.

True innovation gets a cloak, and a blank check if necessary.
Don't get your hopes up, the last hypersonic project to leave the black world was X-37.
I don't think that counts as a hypsersonic aircraft anymore than the shuttle. To date all we have is the x15 from 50 years ago. There were widespread news reports on AM radio circa 86 or 87 winter months i think from reuters that the USAF had "just begun" flight testing of the sr71 successor and more news would be coming out but then the story just went away. I wonder if any of you guys listened to AM remember or heard that news story. I am fairly confident they reported it as capable of mach 5. A year or two later in printed news reports came out of senators being given a showing of a hypersonic aircraft that smelled like sulfur which I am sure was popular enough for most people to remember. Given that was that same time stealth became the new kid on the block i don't put much credit in those stories as the reason to fly fast was to avoid being shot down which stealth did with less technical risk and probably cost
 
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mkellytx

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I don't think that counts as a hypsersonic aircraft anymore than the shuttle. To date all we have is the x15 from 50 years ago. There were widespread news reports on AM radio circa 86 or 87 i think from reuters that the USAF had "just begun" flight testing of the sr71 successor and more news would be coming out but then the story just went away. I wonder if any of you guys listened to AM remember or heard that news story. I am fairly confident they reported it as capable of mach 5.
That's my point, most of our free flight hypersonic data are things falling out of space, rocket powered or a few minutes of airbreathing flight.
 

Josh_TN

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In retrospect, the US invented hypersonic flight...and then abandoned it. It seems with nuclear ballistic missiles, it seemed redundant. I probably would have made that budget choice too. Imagine if the US had thoroughly funded that research since the X-15.
 

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Just trying to keep them straight. So we have (pulled from a couple different articles recently posted):

1. AGM-183A - Air-Launched Rapid Response Weapon (ARRW). "The ARRW, like many of the emerging threats, is an air-launched, rocket-boosted unpowered hypersonic glider. To be developed under a $480 million initial contract, potentially worth $780 million including early production through 2023, the ARRW work is an extension to Lockheed’s pre-existing DARPA contract under which it is building the virtually identical Tactical Boost Glide (TBG) demonstrator." Lockheed Martin Missiles and Fire Control

2. Hypersonic Conventional Strike Weapon (HCSW). The HCSW is a solid-rocket-powered, GPS-guided missile, and is targeted at initial operational capability on existing combat aircraft in fiscal 2022. Lockheed Martin Space Systems

3. Hypersonic Air-breathing Weapon Concept (HAWC). A scramjet-powered missile demonstrator similar in concept to the Air Force Research Laboratory/Boeing X-51A scramjet-powered vehicle that exceeded Mach 5 in a 2013 flight test. Both Lockheed Martin Skunk Works and Raytheon

4. Raytheon, which is partnered with Northrop Grumman Innovation Systems (formerly Orbital ATK) on the scramjet for HAWC, is also in final negotiations with DARPA to develop and test a TBG glide demonstrator. Raytheon’s newest work is believed to be supporting DARPA development of a ship-launched TBG for the U.S. Navy. In July, Lockheed was awarded a $40.5 million Navy Hypersonic Booster Technology Development (HBTD) contract, also believed to be related to this effort.

5. Another one of the projects in the Technology Transition Program is the Advanced Full Range Engine (AFRE), which aims to demonstrate a hybrid propulsion system that would utilize a traditional turbine engine and transition to a Dual Mode Ramjet (DMRJ) for hypersonic travel. Ground tests are planned for 2019 or 2020. This is a joint effort between DARPA and the National Aeronautics and Space Administration (NASA).

6. The Army and Navy are also working on developing hypersonic capabilities. The Army is working with DARPA on studying a ground-launched capability for hypersonic boost glide weapons through the Operational Fires project. This effort was funded at $6 million in FY18 and $50 million in the FY19 request. Operational Fires will also leverage work done on the Air Force TBG program. The Army was previously conducting work on the Advanced Hypersonic Weapon. A successful flight test was conducted in November 2011, but an August 2014 flight test failed due to a problem with the booster rocket used to launch the glide vehicle.

7. The Navy was tasked with a follow-on test using a downsized hypersonic vehicle. Downsizing provides the Navy with the ability to analyze possible future ship-launched capabilities. The Navy's Strategic Systems Programs office conducted this test in October 2017, dubbed Flight Experiment-1. A rocket carrying the glide vehicle was launched from Hawaii, after which the glide vehicle flew more than 2,000 miles in about 30 minutes. Other details of the test were classified.

8. In addition to the ARRW, HCSW, TBG, and HAWC, Lockheed's "Skunk Works" is believed to still be working on the High Speed Strike Weapon, which sources say is a tactical missile in the Mach 3-plus category that resembles its D-21 drone, which USAF launched from SR-71s and B-52s in the 1970s. The HSSW is derivative of the Revolutionary Approach to Time Critical Long Range Strike program Lockheed explored with the Navy in the early 2000s. (This sounds more like speculation as they seem to be conflating two different programs.)
We need to keep up the good work in this field and stay ahead before we are surprised and passed up in this technology
 

AN/AWW-14(V)

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Aerojet Rocketdyne and Northrop Grumman have demonstrated large scale scramjet technologies by testing engines with thrust levels exceeding 5,897 kg as part of the US Air Force’s (USAF’s) Medium Scale Critical Components (MSCC) test programme.

USAF spokesman Bryan Ripple said on 29 December that the service will move forward with larger scale, multi-mission platforms at speeds greater than Mach 5 because both propulsion systems met the service’s performance expectations. The MSCC sets the foundation for the design of hypersonic propulsion systems across a broad range of vehicle scale and Mach operability.

The USAF in November 2020 completed a series of advanced air-breathing hypersonic engine tests on a 5.5 m Aerojet Rocketdyne scramjet engine, according to a company statement. Ripple said on 16 December that the tests were conducted at Mach 4 and greater speeds.

Northrop Grumman achieved over 5,897 kg of thrust with its own scramjet engine, the USAF announced in August 2019. The company’s engine, also 5.5 m long, endured 30 minutes of accumulated combustion time during nine months of testing. Pat Nolan, Northrop Grumman vice president for missile products, was quoted by the USAF in August 2019 as saying that these 5.5 m scramjets are fighter-engine sized.

Ripple said that both Aerojet Rocketdyne and Northrop Grumman, to make testing more affordable, made compromises to their designs to use common flow path hardware. This provided a demonstration of large-scale scramjet technologies, he said, but did not provide for absolute best performance by either team. This is why the USAF is not comparing them against each other, Ripple said.

 

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Aerojet Rocketdyne and Northrop Grumman have demonstrated large scale scramjet technologies by testing engines with thrust levels exceeding 5,897 kg as part of the US Air Force’s (USAF’s) Medium Scale Critical Components (MSCC) test programme.

USAF spokesman Bryan Ripple said on 29 December that the service will move forward with larger scale, multi-mission platforms at speeds greater than Mach 5 because both propulsion systems met the service’s performance expectations. The MSCC sets the foundation for the design of hypersonic propulsion systems across a broad range of vehicle scale and Mach operability.

The USAF in November 2020 completed a series of advanced air-breathing hypersonic engine tests on a 5.5 m Aerojet Rocketdyne scramjet engine, according to a company statement. Ripple said on 16 December that the tests were conducted at Mach 4 and greater speeds.

Northrop Grumman achieved over 5,897 kg of thrust with its own scramjet engine, the USAF announced in August 2019. The company’s engine, also 5.5 m long, endured 30 minutes of accumulated combustion time during nine months of testing. Pat Nolan, Northrop Grumman vice president for missile products, was quoted by the USAF in August 2019 as saying that these 5.5 m scramjets are fighter-engine sized.

Ripple said that both Aerojet Rocketdyne and Northrop Grumman, to make testing more affordable, made compromises to their designs to use common flow path hardware. This provided a demonstration of large-scale scramjet technologies, he said, but did not provide for absolute best performance by either team. This is why the USAF is not comparing them against each other, Ripple said.

Then what was the problems in propulsion with the demonstrator sr72 that led to the article being canceled?
 

mkellytx

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Then what was the problems in propulsion with the demonstrator sr72 that led to the article being canceled?
There's no demonstrator, to be canceled something has to first be a program of record, SR-72 is a Skunk Works IRAD project. Blackswift was the air breathing portion of the DARPA Falcon program, but was canceled before X-51 ever flew, similar concept though. IIRC, it was still early in the program, no metal cut, don't even think they had an engine yet, but time fades the memory.

The article @bobbymike posted nails the difficulty of scaling things up.
 

rooster

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Then what was the problems in propulsion with the demonstrator sr72 that led to the article being canceled?
There's no demonstrator, to be canceled something has to first be a program of record, SR-72 is a Skunk Works IRAD project. Blackswift was the air breathing portion of the DARPA Falcon program, but was canceled before X-51 ever flew, similar concept though. IIRC, it was still early in the program, no metal cut, don't even think they had an engine yet, but time fades the memory.

The article @bobbymike posted nails the difficulty of scaling things up.

Not talking about black swift, black horse or black anything. There were plans to build a demonstrator. Quellish even commented on it.
 

mkellytx

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Not talking about black swift, black horse or black anything. There were plans to build a demonstrator. Quellish even commented on it
Yes, the proposal to build a F-22 sized demonstrator. Still, can't cancel what's not funded, until there's a program of record this is a LM marketing campaign. Their IRAD seems to be focused on computer design tools and 3D additive manufacturing amongst other things. The dead give away is the articles from 2017 say demonstrator 2022/2023, last year's articles say demonstrator mid 2020's SR-72 2030. Also, the executives quoted in later articles say things like the demonstrator couldn't be built 5 years ago, because the digital tools and additive manufacturing didn't exist.
 

greenmartian2017

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I have been reading this thread for some time now.

This needs to be said explicitly: Much of the US chronology in regards to hypersonic developments (flight articles and propulsion systems) remains black (tied up in classified programs over time, beginning with efforts back in the 1960s). So much of this remains classified that it is very difficult to have an accurate, decently encompassing discussion about this subject field from an historical viewpoint (although there have been some noteworthy efforts in this regard: Richard Hallion's multi-volume work is such an example) that isn't faced with (in my opinion, numerous) gaps. But let's not forget that even with efforts to get things declassified there are long delays: one 1960s-era hypersonic vehicle program (apparently manned) was ISINGLASS. Decently intact declassified information on this program appeared in 2010 (although there was some release in 2006 also). But rest assured that what has been released on it is not "all" the information that CIA and NRO have in their archives about ISINGLASS. (Ditto for projects like RHEINBERRY, and so on.)

A manned hypersonic vehicle that either flies in low Earth orbit, or just about flies at that altitude (highest endo-atmospheric), has been a very attractive subject for US policy makers for a very long time, over time. Just because the declassified literature "dies out" by 1971 or 1972 doesn't mean the concept wasn't pursued beyond that date. It just means that government declassification officials have deemed that follow-ons to ISINGLASS aren't to be acknowledged, or to be known by the public at this time.

Propulsion systems that operate in the hypersonic speed range (not talking about rockets or rocket-propelled things here) seem to be even more sensitive information-wise.

What a person has to do is look in the "gray" literature for hints. That's where some of the missing story lies. But only some of the story.

My two cents.
 

marauder2048

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A manned hypersonic vehicle that either flies in low Earth orbit, or just about flies at that altitude (highest endo-atmospheric), has been a very attractive subject for US policy makers for a very long time, over time. Just because the declassified literature "dies out" by 1971 or 1972 doesn't mean the concept wasn't pursued beyond that date. It just means that government declassification officials have deemed that follow-ons to ISINGLASS aren't to be acknowledged, or to be known by the public at this time.
Even ISINGLASS seems to have fallen down in part on IR vulnerability analysis.

It's a recurring theme; you can find papers from the 80's on IR tracking of transatmospheric vehicles.

Detecting and tracking the much more modest SR-72 via a small sat constellation equipped with
some basic MWIR sensors looks quite achievable.

You are talking about 2000 K scramjet exhaust and IR spectra that's not going to be much attenuated
against spaceborne sensors at the typical scramjet altitudes.

This constellation probably isn't going to be transmitting fire control quality tracks but
accurate enough warning such that vulnerable sites can get their counter-ISR techniques in place.
 

TomcatViP

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I don't like this approach that by trying to embrace theorically all cases missed to study the doctrinal aspect.
Hypersonics is not a domain segregated from other force employment like can be an air force when compared to manoeuvring ground armies. It's a vehicle for an effect (kinetic/ISR/nuclear...). On the extended battle field of tomorrow, against the millions men armies and militias, Hypersonics will provide time sensitive precision strike (in the case of kinetic) akin to what where the Stuka* during the Blitzkrieg. Speed is there to have range where a single centralized user can cover hundred of miles without having to disperse their forces.
In other terms, IMOHO, there is no dogmatic question left today. The odds are that such scenario will be the one and that only shapes the doctrinal aspect.
There will be stealth. There will be space. And all that have the ability will use Hypersonics.

*I am not thinking at an airframe here but at long range fire
 
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