DARPA's new X-76

To be clear, this is not a power-point program but a continuation of a long-standing design work with Bell.

Two articles that cover this in depth are: 1. Revised Fold-Away Rotor Aircraft Concepts Emerge From Special Operations X-Plane Program. December 2024: https://www.twz.com/air/revised-fold-away-rotor-aircraft-con...

2. Bell’s Plan To Finally Realize A Rotorcraft That Flies Like A Jet But Hovers Like A Helicopter. September 2021: https://www.twz.com/41997/bells-plan-to-finally-realize-a-ro...

The second article covers decades of prior wind tunnel testing on the folding rotor concept.

It looks like a maintenance nightmare with those clutches to decouple the blades and the mechanisms to have them folded during cruising. Does it even improve substantially in anh metric over the V280 to put money into it?

Cool, I guess this should be able to hover in much more "austere" environments than the F-35B STOVL and the Harrier Jet. Tiltrotor with folding rotor blades sounds very mechanically complex and challenging though.

I don't understand the purpose of the Xenon taillight.

I think the blades are added there for deception, most likely it won’t have blades.

So it's an Osprey with a jet in the back?

Why won't they adopt one of Sikorsky's compound helicopters already? They're beautiful and elegant solutions to this problem.

From the image it doesn't look balanced for VTOL when the propellors are vertical. Also are the jets enabled during VTOL?

So it has jet engines that blades unfold and attach to during takeoff and landing? Why not always use the blades?

I'm confident with the stellar service and safety record of the V-22 that an even more complex tiltrotor will be a standout success for the military.

I’d go for simplicity and do a tail lander.

Isn't this need already met by the Bell V280 that the army already selected for it's Blackhawk replacement? What is the big innovation they are going for here?

“ With SPRINT, we're not just building an X-plane; we're building options”. Found the guy who couldn’t be bothered to write his own press release…

Someone has played the new Deus Ex games

The swedish gripen can do mach2 (2300km/h) and does not need a traditional runway (500 meters of something "flat enough" will do). I assume its way cheaper than something like this.

I can't access darpa.mil. Was it slashdotted because of the article being posted here, or now it is unavailable outside of US?

Hmmm... that just looks like problems. It's a lot of mechanical parts that always have to work correctly.

I wonder is Iran would have gone different if we had captured the Ayatollah instead of killing him. A stealth drop ship like this would have allowed that to happen. The reason why regimes are more likely to negotiate when you capture their leaders is because you might release them. (not a good day for the usurper.)

Different engines for different phases of flight? It has been tried many times and never really works. Such craft can be made to fly, but never well. The answer has to come from using one set to power all phases.

Id be interested in seeing a turboprop that can transition to a turbofan/jet once the prop is folded away. The f-35 was a step in this direction.

that already exists in the form of Saab Gripen :)

I wonder what the motivation behind this is. Tactically, why ever show your latest weapon? What is the strategic purpose of this? It's like if I message my opponent in SC2 and tell them exactly what I'm going to tech to. That's ... insane right? Why would anyone do that?

I don't understand the purpose of the Xenon taillight.

I think the blades are added there for deception, most likely it won’t have blades.

I’d go for simplicity and do a tail lander.

Someone has played the new Deus Ex games

Id be interested in seeing a turboprop that can transition to a turbofan/jet once the prop is folded away. The f-35 was a step in this direction.

To be clear, this is not a power-point program but a continuation of a long-standing design work with Bell.

2. Bell’s Plan To Finally Realize A Rotorcraft That Flies Like A Jet But Hovers Like A Helicopter. September 2021: https://www.twz.com/41997/bells-plan-to-finally-realize-a-ro...

The second article covers decades of prior wind tunnel testing on the folding rotor concept.

>decades of prior wind tunnel testing on the folding rotor concept

Oof, I wish I had a job like that.

The V280 is designed to be cheap (a very relative term here).

Reading between the lines, I suspect "fast, but also expensive" was a design option that popped up and was not chosen earlier in the V280 program and now Darpa wants to pay to see where it goes.

it also has stealth. This is a complete disaster. The only purpose of this stealth ship is to steal leaders and or go inside cave lairs and blow them up.

The next generations of accidents are going to be even more looney-tunes in nature.

So it's an Osprey with a jet in the back?

Usually with these programs, they just commission an artist with some vague description, like they tell him to draw a futuristic VTOL aircraft, these pics have zero bearing on what gets delivered.

Sometimes they even take the piss with this, like in this video for a next-gen engine, where you can see their engine doesn't even fit in their fantasy aircraft:

https://www.youtube.com/watch?v=vCHun6rxQm0

Why won't they adopt one of Sikorsky's compound helicopters already? They're beautiful and elegant solutions to this problem.

Because Sikorski can't make them work. Sure, they can take off and fly fast in a straight line, but they haven't been able to demonstrate sufficient maneuverability due to vibration problems in the rotor head. They are also very tall, prohibitively so for existing shipboard hangar, which would otherwise seem to be their advantage over tiltrotor platforms.

From the image it doesn't look balanced for VTOL when the propellors are vertical. Also are the jets enabled during VTOL?

I'm betting the person who created the "artist rendering" isnt an aeronautical engineer.

So it has jet engines that blades unfold and attach to during takeoff and landing? Why not always use the blades?

I'm confident with the stellar service and safety record of the V-22 that an even more complex tiltrotor will be a standout success for the military.

If you look at the V-22 safety record in the context of the level of technical development, it is pretty good (e.g. compare to helicopters and aircraft from the 60s). The first production generation of a brand new type of vehicle is always going to be complicated, and virtually all of the V-22 mishaps come from the "new" components and procedures.

The fundamental tradeoff with tiltrotor platforms is that you trade significantly increased speed for significantly increased complexity. What that means is your battlefield survivability goes up when dealing with any opponent with meaningful air defenses, but at the cost of increasing your "resting" accident rate when most peacetime accidents are consequences of maintenance and/or procedural issues.

16 hull losses per ~400 units built is not exactly a stellar safety record.

Or I guess you mean /stellar?

Isn't this need already met by the Bell V280 that the army already selected for it's Blackhawk replacement? What is the big innovation they are going for here?

+50% top speed over the V280. Bell offered it as an alternative to the V280 in the early stage of the contract, but it was judged too experimental (and probably too expensive). Apparently DARPA is funding further development of the concept.

“ With SPRINT, we're not just building an X-plane; we're building options”. Found the guy who couldn’t be bothered to write his own press release…

I'm quite fond of the caption, which describes a "a proof-of-concept technology demonstrator that aims to demonstrate technologies and concepts"

I think I'd rather have them working on airplane tech rather than writing airplane tech press releases. With this approach, it's not just a tactical thing; it's relieving the burden of wordsmithing from technical people.

Good to hear that the DoD's new contract with OpenAI is solving all the most important problems...

It's a quote from someone...?

It feels like DARPA has fallen so far. In a post-Salt Typhoon era it's really hard to imagine them as dynamic, best-in-class innovators anymore.

The swedish gripen can do mach2 (2300km/h) and does not need a traditional runway (500 meters of something "flat enough" will do). I assume its way cheaper than something like this.

I suppose the argument is that X-76 could work in environments without roads. But that also implies without fuel or any other support on the ground.

I can't access darpa.mil. Was it slashdotted because of the article being posted here, or now it is unavailable outside of US?

Inaccessible from France. With family.dns.mullvad.net private DNS.

I can access it from the UK

Hmmm... that just looks like problems. It's a lot of mechanical parts that always have to work correctly.

that already exists in the form of Saab Gripen :)

>decades of prior wind tunnel testing on the folding rotor concept

Oof, I wish I had a job like that.

it also has stealth. This is a complete disaster. The only purpose of this stealth ship is to steal leaders and or go inside cave lairs and blow them up.

The next generations of accidents are going to be even more looney-tunes in nature.

Usually with these programs, they just commission an artist with some vague description, like they tell him to draw a futuristic VTOL aircraft, these pics have zero bearing on what gets delivered.

Sometimes they even take the piss with this, like in this video for a next-gen engine, where you can see their engine doesn't even fit in their fantasy aircraft:

https://www.youtube.com/watch?v=vCHun6rxQm0

16 hull losses per ~400 units built is not exactly a stellar safety record.

Or I guess you mean /stellar?

He is being sarcastic.

I'm quite fond of the caption, which describes a "a proof-of-concept technology demonstrator that aims to demonstrate technologies and concepts"

Brought to you by the Department of Redundancy Department.

The technical people were never wordsmithing, they just didn't hire a technical writer. Instead of freeing up someone to do more design work, it freed someone to interview for a new job. I hope they get it.

You're absolutely right.

Good to hear that the DoD's new contract with OpenAI is solving all the most important problems...

It's a quote from someone...?

... who probably wrote their prepared PR statement with an LLM.

It feels like DARPA has fallen so far. In a post-Salt Typhoon era it's really hard to imagine them as dynamic, best-in-class innovators anymore.

This administration doesn't really prioritize anything that has to do with intelligence, so advanced research was obviously going to fall by the wayside.

I suppose the argument is that X-76 could work in environments without roads. But that also implies without fuel or any other support on the ground.

Inaccessible from France. With family.dns.mullvad.net private DNS.

I can access it from the UK

Still up here in the US

"Please don't post shallow dismissals, especially of other people's work. A good critical comment teaches us something."

https://news.ycombinator.com/newsguidelines.html

The Osprey killed a lot of Marines over the past decades. It took a while to work out the issues. Hopefully we will remember what the Osprey taught us.

I don't think whatever is negotiated with Iran's current regime would actually be honored by them. They may commit something to get their leader back, but won't be keeping the promises.

Their self stated goal is destruction of Israel and US. They could have chosen peace and not have funded proxies across the middle east. Their choice of aggression by whatever means they have at their disposal just shows what their long term strategy would be.

They have shown the intend. They just didn't have the capacity to follow through. Once they gain the capacity, they could go extreme lengths. Just see how they attacked their neighbors who were not party to the war.

> A stealth drop ship like this would have allowed that to happen.

Yeah, I saw that Agents of S.H.I.E.L.D. episode too.

Sadly, we might need some more intensive vibranium research before it becomes reality.

Where do the 14 soldiers sit in the Gripen?

It's not a tactical choice- it's strategic deterrence, and it's not insane at all!

The US has always had a policy of messaging programs, with a lean toward classifying some percentage of the specific capabilities.

There's a reason that F-35 program was publicized by the US government as the program was under development. It makes the US air force even scarier, which discourages adversaries from thinking about conventional warfare with America.

That said- you won't see any detailed pics of the inside of an F35 cockpit, or a detailed look at the heads up display in the fancy helmet. That's top secret, because those making those details public don't offer enough additional deterrence to justify the risk to the program.

This isn't a new weapon, this is a test platform for various ideas, none of which are new or secret. Also, there are not many groundbreaking advancements left in military aviation. Most are just fairly incremental engineering or manufacturing improvements. (Military space technology might be a different story, though.)

The only other nation with the potential to develop a high-tech military plane that could rival US technology would be China. But if we ever got into a war with China, they wouldn't need superior technology to win. They could win via superior manufacturing capacity and the sheer number of people they can draft into service at a moment's notice.

I think they just show what it can be seen, like any country with advance military developments.

They won't show you everything.

Have you ever heard about those sound/sonic (or something similar) weapons the US used in Maduro's kidnap operation? Venezuelan soldiers said (pero some publications on the internet) that they never saw anything alike, leaving them completely disoriented and helpless?

Soldiers now can even see thermal figures through walls or solid materiales, and the same time, bacome invisibles.

It's more than sci-fi.

The V280 is designed to be cheap (a very relative term here).

Reading between the lines, I suspect "fast, but also expensive" was a design option that popped up and was not chosen earlier in the V280 program and now Darpa wants to pay to see where it goes.

Hard to be more expensive than F-35B.

I'm betting the person who created the "artist rendering" isnt an aeronautical engineer.

Wager $10 it's a LLM prompt.

He is being sarcastic.

Brought to you by the Department of Redundancy Department.

> The technical people were never wordsmithing, they just didn't hire a technical writer. Instead of freeing up someone to do more design work, it freed someone to interview for a new job. I hope they get it.

Do technical writers work on press releases? This sounds more like a job for the public relations/corporate communications department.

You're absolutely right.

... who probably wrote their prepared PR statement with an LLM.

I have always talked/written like this. now that LLMs do it in a similar enough way, my own writing gets called AI slop. I just wish my rotator cuffs knew I was a robot.

This administration doesn't really prioritize anything that has to do with intelligence, so advanced research was obviously going to fall by the wayside.

Hard to be more expensive than F-35B.

The F-35 is cheaper then some new production 4th generation fighters at this point.

Still up here in the US

"Please don't post shallow dismissals, especially of other people's work. A good critical comment teaches us something."

https://news.ycombinator.com/newsguidelines.html

The Osprey killed a lot of Marines over the past decades. It took a while to work out the issues. Hopefully we will remember what the Osprey taught us.

> A stealth drop ship like this would have allowed that to happen.

Yeah, I saw that Agents of S.H.I.E.L.D. episode too.

Sadly, we might need some more intensive vibranium research before it becomes reality.

I think they just show what it can be seen, like any country with advance military developments.

They won't show you everything.

Soldiers now can even see thermal figures through walls or solid materiales, and the same time, bacome invisibles.

It's more than sci-fi.

Do technical writers work on press releases? This sounds more like a job for the public relations/corporate communications department.

Or, at least, my take on GPT. :) I promise I am a human.

I have always talked/written like this. now that LLMs do it in a similar enough way, my own writing gets called AI slop. I just wish my rotator cuffs knew I was a robot.

It's probably good signal at least, if not a bit of a harsh thing to say that I don't mean in a bad way, that your writing was bland or mediocre since LLMs are basically regression to the mean.

Skimping on the service again, are we?

I don't think whatever is negotiated with Iran's current regime would actually be honored by them. They may commit something to get their leader back, but won't be keeping the promises.

A very good response to the parent comment and summary of the current situation.

AIUI the Iranian attack on Arab countries is strategic, increasing energy costs pressures the US to stop military action. However the US and allies were prepared with set aside oil reserves, increasing supplies from other sources, and reducing Iran's ability to interfere with shipping.

Major warfare always has tragic effects, but against regimes actively pursuing destruction of other nations, return of fire is a rational response.

Where do the 14 soldiers sit in the Gripen?

On the wings, obviously, for quick deployment. Maybe I mean early deployment.

It's not a tactical choice- it's strategic deterrence, and it's not insane at all!

The US has always had a policy of messaging programs, with a lean toward classifying some percentage of the specific capabilities.

Yes, but even if the US didn't release the specifications of the F35, other countries around the world would rapidly figure out most of the capabilities anyway from photos, videos, and casual observation. (In other words, they'd know soon enough WHAT it can do but not necessarily HOW it does it.)

>They could win via superior manufacturing capacity and the sheer number of people they can draft into service at a moment's notice.

Even with their manufacturing capacity they don't have remotely enough boats to get a nontrivial fraction of those people to the US mainland, and the majority of those people can't swim, so they wouldn't help in taking the US mainland, a requirement to "win" a serious war. Their entire armed forces is also almost completely lacking in combat experience, and in their last skirmish (against some unarmed Indian soldiers in the mountains) 30+ soldiers Chinese tragically drowned, due to the aforementioned lack of swimming ability.

They could just cease all shipping. The consequences would be legendary.

A very good response to the parent comment and summary of the current situation.

Major warfare always has tragic effects, but against regimes actively pursuing destruction of other nations, return of fire is a rational response.

>They could win via superior manufacturing capacity and the sheer number of people they can draft into service at a moment's notice.

They could just cease all shipping. The consequences would be legendary.

Or, at least, my take on GPT. :) I promise I am a human.

It's probably good signal at least, if not a bit of a harsh thing to say that I don't mean in a bad way, that your writing was bland or mediocre since LLMs are basically regression to the mean.

Skimping on the service again, are we?

On the wings, obviously, for quick deployment. Maybe I mean early deployment.

Shades of: Being strapped to the sponsons of an AH-64 is one wild, but potentially life-saving ride.

https://www.twz.com/38435/this-is-all-the-survival-gear-that...

The F-35 is cheaper then some new production 4th generation fighters at this point.

I've had to eat some humble pie and moderate my assessment of the F-35. It still does have a lot of issues, for sure, but it turns out if you divide an eye wateringly large number by another impressively large number, the result can be a lot better than I thought it would be.

It's lot more about operational costs and project deliverables than plain sticker shock, and it is turning out to be a capable platform.

The sticker price is competitive but the cost per flight hour and the availability factor is pretty horrifying. Factoring in the cost of flying and the availability makes the Grippen about half the cost.

I wonder if the flight hour cost of F 35 includes the maintenance it's undergoing when it's not available.

Eliminating one of the battlefield's most difficult choices – between the high speed of an aircraft that needs a runway and the go-anywhere flexibility of a slower helicopter – is the goal of DARPA’s SPeed and Runway INdependent Technologies (SPRINT) program.

Announcing DARPA’s Newest X-Plane, X-76

SPRINT’s experimental aircraft, officially revealed as the X-76, is now being built by Bell Textron, Inc. following a successful Critical Design Review (CDR). The designation places it within the historic lineage of X-planes that have long served to test the boundaries of aviation. Coinciding with the country’s 250th anniversary, the X-76 designation is a deliberate nod to the revolutionary spirit of 1776.

The SPRINT program is a joint effort between DARPA and U.S. Special Operations Command to advance technologies that could break the long-standing military trade-off between the high speed of fixed-wing aircraft and the agile, runway-independent operations of vertical takeoff and landing platforms. The design, construction, and flight testing of the X-76 will drive innovative, runway-independent, vertical-lift capability with jet-like cruise performance and inform future needs.

The Mission: Breaking Aviation's Oldest Trade-Off

SPRINT began its second phase (Phase 2) in May 2025 following the downselect to Bell. With the successful completion of the CDR, the program will shift focus to manufacturing, integration, assembly, and ground testing of the X-76 demonstrator. The demonstrator will mature technologies necessary for a transformational combination of the following capabilities:

Achieve cruise at speeds exceeding 400 knots
Hover in austere environments
Operate from unprepared surfaces

"For too long, the runway has been both an enabler and a tether, granting speed but creating a critical vulnerability," said Cmdr. Ian Higgins, U.S. Navy, serving as the DARPA SPRINT program manager. "With SPRINT, we're not just building an X-plane; we're building options. We're working to deliver the option of surprise, the option of rapid reinforcement, and the option of life-saving speed, anywhere on the globe, without needing any runway."

Phase 2 will be followed by a flight test program in Phase 3, which is planned for early 2028.