12 ms·

DARPA Moves Forward on X-65: Plane with no moving control surfaces

304 points by wolverine876 3y ago

theflyestpilot 3y ago
I truly hope that same Wii sports -esque music in the video also emits while this thing shoots missiles
sbierwagen 3y ago
>by using jets of air from a pressurized source Presumably bleed air from the jet engine compressor, which means this design won't work for piston-engine propeller drones, which is the usual configuration for small non-stealth drones. I wonder where in the copyediting process this got left out, because otherwise this design would be bonkers. >Eliminating external moving parts is expected to reduce weight External moving parts, of course, since it'll have just as many valves to control the flow of bleed air as a regular hydraulic setup. I wonder what material they're making the wings out of-- bleed air is pretty hot.
- christkv 3y ago
  What happens when propulsion fails on this. Does not seem likely it will be able to perform a glide landing.
  - AdamN 3y ago
    It's unmanned so a self-destruct mechanism is probably the straightforward solution - or disable power and use a parachute
  - londons_explore 3y ago
    Backup air reservoir?
  - justin66 3y ago
    It's an X plane, and it's unmanned. If propulsion fails, it will presumably crash in the desert. Some of the press on this talks about weight savings. If they're really serious about that, well... none of their flights are intended to go above Mach 0.7. Possibly they could deploy a ballistic parachute like Cirrus airplanes offer.
  - sgjohnson 3y ago
    Presumably, this would be operated in hostile territory, so nobody would particularly care about it turning into a giant fireball upon crash landing. Or self-destructed when still airborne.
  - deleted 3y ago
    [deleted]
- boxed 3y ago
  Couldn't it have just one central compressor for this air?
  - londons_explore 3y ago
    I suspect it needs rather large qualities of air. Ie. Cubic meters per second. It's gotta be a modified engine that lets you extract compressed air.
    - krisoft 3y ago
      > It's gotta be a modified engine that lets you extract compressed air. That is basically a standard feature on every jet engine. It is called bleed air. https://en.wikipedia.org/wiki/Bleed_air https://en.wikipedia.org/wiki/Bleed_air
  - usrusr 3y ago
    Yes? For example that central jet engine that the plane already has? Doesn't change anything about requiring additional moving parts to control where the compressed air goes and where it goes not. The goal of this entire exercise is not to expel some extra compressed air in places where previously regular outside flow happened, the goal is to control the plane by changing when and where that disturbance by extra air happens.
    - Toutouxc 3y ago
      To be fair, the original comment was about piston engine powered aircraft. These would really need either a separate compressor/blower or a complicated modification of the exhaust system.
      - usrusr 3y ago
        True, must have missed that, deep branches on higher rated sibling comments. And at the time when I did skim the actual grandparent, I dismissed the part about piston because I don't believe that any of the suspected benefits of this pressed air disturbance control scheme could ever be meaningful in the realm of piston-engine drones. Control surfaces are cheap.
- LargeTomato 3y ago
  > Presumably bleed air from the jet engine compressor. We don't know that and this is the very first prototype so it could absolutely evolve over time. > Which means this design won't work for piston engine propeller drones In its current, nascent configuration where we are prototyping a new technology using a testbed platform, maybe. Again, this is not a commercial-ready product it's a prototype. > Which is the usual configuration for small non-stealth drones So this prototype doesn't fit on a $10 quad copter so it's... Flawed? > I wonder where in the copyediting process this got left out Prototype. > Because otherwise this design would be bonkers. More or less bonkers than dismissing a completely novel aviation technology before it's even gotten off the ground? More or less bonkers than dismissing a completely novel technology because it doesn't work for your one specific hypothetical use case?
  - rmccue 3y ago
    > So this prototype doesn't fit on a $10 quad copter so it's... Flawed? I didn’t read the original as meaning non-military drones, rather non-stealth military drones. For example, to the OP’s point, the Predator drone is powered by a piston engine - I’m not overly familiar with other military drones, but stands to reason other UAVs use similar tech.
    - lupusreal 3y ago
      They're talking about this prototype doing mach 0.7, so it's a safe bet they intend it to have a turbofan. That's much faster than a MQ-1/MQ-9 and also faster than a (turbofan) MQ-20. Dismissing this design because it requires a jet engine just seems bizarre. Like okay, it doesn't work with piston props... so what?
  - adrian_b 3y ago
    > We don't know that and this is the very first prototype so it could absolutely evolve over time. The high-pressure air must come from a compressor, either a separate compressor or the jet engine compressor. Obviously it is much cheaper and much more compact to use bleed air from the jet engine compressor, than to include a second compressor, only for maneuvering. On an aircraft without a turbo-engine adding a compressor would increase the cost and the energy consumption a lot in comparison with the traditional methods of steering the aircraft, so it is not advantageous. However this method without control surfaces should also be usable with turboprop engines, not only with jet engines.
- fidotron 3y ago
  BAE built a much smaller test UAV of the same idea in 2010 https://en.wikipedia.org/wiki/BAE_Systems_Demon https://en.wikipedia.org/wiki/BAE_Systems_Demon which was indeed a mixture of bleed air and exhaust.
- krisoft 3y ago
  > bleed air is pretty hot. Initially yes. But then it can be cooled by expanding it or mixing it with cold air. This is pretty routine. After all the air you breath on airlines is coming from bleed air too. > it'll have just as many valves to control the flow of bleed air as a regular hydraulic setup Sure, but that's not the heavy stuff. The fact that bits of the wing has to be independently movable means that it has to be much heavier. If the whole wing would be just one piece you could presumably support it more efficiently.
- deleted 3y ago
  [deleted]
- ranger207 3y ago
  There's been a bunch of piston engine planes with hydraulic pumps; I don't think a pneumatic one will be much more difficult
- Aloisius 3y ago
  > Presumably bleed air from the jet engine compressor It appears to come from an auxiliary power unit. https://youtu.be/G_jhcqGjUww?t=43 https://youtu.be/G_jhcqGjUww?t=43
Lastodon 3y ago
Title is false. The plane has moving control surfaces.
- boxed 3y ago
  Only to compare to, and as backup when they are still unsure about the flight performance of the new system.
  - justin66 3y ago
    A design in this vein might want to keep moving control surfaces locked down in all but extraordinary circumstances: spin recovery or flameout. Maximum g turns? For that matter, it's not crazy to think that they'd want to keep the moving control surfaces available for takeoff and landing.
    - usrusr 3y ago
      I went through this idea in my head reading the sibling speculations about civilian use and discarded the idea: when you have the control surfaces, there's no cost in using them. In terms of aerodynamic inefficiency I'd expect it to be a tie at best, both are disturbances that make the flow worse to achieve an effect. If they do discover a way to improve aerodynamic qualities with compressed air, chances are civilian aircraft would just switch it on whenever it helps and keep control going through conventional control surfaces just like before.
foota 3y ago
It's not mentioned in the article, but I wonder if part of this is about stealth. I imagine the moving control planes might create additional cross section vs not having them?
- londons_explore 3y ago
  It sounds like this option could let you make the wings and tail of the plane metal-free, which is good for hiding from radar
  - Terr_ 3y ago
    > the wings and tail of the plane metal-free At some point that's like trying to make someone invisible by making their skin--and only their skin--transparent. It'll backfire when all the twisty complicated still-important stuff on the inside stands out even more.
    - superb_dev 3y ago
      What is the resolution of modern radar? The important core might not be big enough to see
      - Vecr 3y ago
        It's not about resolution, you can see stars easily that your eyes can't resolve as a disk. It's about magnitude.
    - c22 3y ago
      With this scheme it seems you could concentrate all the twisty complicated stuff to a small area in the body of the plane and use rubber hoses to deliver the air to the control surfaces.
      - Terr_ 3y ago
        Internal space of wings is often used for storing fuel. I'm not sure if there are any studies on how well modern radar could detect sloshy blobs of kerosene flying through the sky. (Inside totally radar-transparent containers.)
cm2187 3y ago
So if the engine shuts down you lose control of the plane? Hope they will install ejection seats if it is to be used in an airliner...
- foota 3y ago
  It's DARPA, its probably intended for a drone.
  - cm2187 3y ago
    Not sure, it says "...help us better understand how AFC could revolutionize both military and commercial craft in the future"
    - wiz21c 3y ago
      I'd venture to say that most of the airline transport is goods, not people. So an unmanned plane would be OK...
      - cm2187 3y ago
        Even if it's cargo and unmanned, you can't let massive objects full of fuel that become uncontrollable if the engine fails fly over populated areas.
        bbor 3y ago
        Shouldn’t*. We let massive objects full of fuel that become uncontrollable if the engine fails drive through populated areas, and by the common clay of the west no less! Economics trumps safety, it’s all about the trade off our society is willing to make. And our society is willing to make some pretty huge ones. I for one would not be worried about a slightly higher possibility of getting hit by a falling plane, unless this system was provably very unreliable or something.
        baybal2 3y ago
        [dead]
LargeTomato 3y ago
Darpa is testing a completely novel type of flight control and all these HN comments are just nitpicking irrelevant things, missing the forest through the trees, and saying "it won't work on propeller drones". The quality of discussion on this website is abysmal.
- deleted 3y ago
  [deleted]
- robertlagrant 3y ago
  Honestly, the quality is only lowered by this comment. You already replied to the drones thing. Writing a second, ranting, comment at the top level scaling up that comment to represent all of HN discussion of all time is just a bit silly.
  - LargeTomato 3y ago
    Anything about foreign policy, IR, and aerospace is reddit-tier. Probably more subjects too but they are out of my area of expertise.
    - mdhb 3y ago
      Add in anything that’s even remotely related to intelligence or defence which is typically just filled with qanon style nonsense. I’ve noticed it for years as well, you aren’t wrong.
      - bombcar 3y ago
        Except for some very specific knowledgeable posters, the vast majority of all Internet comments could be replaced by a LLM. Including this one. The key is to not post them yourself and to let the good ones shine.
        ChainOfFools 3y ago
        I don't know, I think there needs to be some form of unambiguous BS pushback signal, a gradient that starts with minimal intrusion on discussion along the lines of "people are starting to notice that some of us are talking past our pay grade." Not saying anything at all amounts to an endorsement of penalty free bullshiting, and after enough of this the hard-won cultural expectations start to shift about what constitutes acceptable participation. There's a spectrum between Reddit on one end, and the typical IRC channel fiefdom with its mod-permissioned voicing, invisible banhammer tripwires, and admonitions to LuRK MoAR, on the other, and I think HN is in a sweet spot/zone somewhere between those extremes, but perhaps might need an adjustment in the direction of the latter. Downvoting/flagging somewhat furnishes this signalling, but it's too ambiguous of a signal and is often abused by people who simply want to suppress information that is perfectly valid but not to their liking. This is where a slashdot type of lightly sentiment-coded moderation system really may be worth bringing back into fashion.
wolverine876 3y ago
From another article linked in a comment: "We have tried to conceive a demonstrator that can accommodate all types of active flow control in a diverse range of aircraft planforms and uses for AFC, whether for high-lift, flight control or other objectives,” says Aurora’s government programs lead, Graham Drozeski. https://www.aerospacetestinginternational.com/features/is-active-flow-control-the-next-step-in-flight-controls.html https://www.aerospacetestinginternational.com/features/is-ac...
paulsutter 3y ago
Active flow control (AFC) can be pneumatic or electric Given a small Helion-type fusion reactor, crazy aircraft will be possible from [1]: > Electric AFC techniques use arrays of electrodes to discharge aerodynamic or electrical pulses to locally alter airflow. Effectors called synthetic jets – millimeter-wide openings in the aircraft surface that open into centimeter-wide cavities with diaphragms – rely on rapid voltage pulses to make diaphragms oscillate inward or outward, creating airflow sucking or blowing effects, much like a human lung. > Electrically powered plasma actuators discharge pulses of electricity into the air through electrodes. The heat from the electricity turns the air into plasma, thermally altering flow vectors. All of these techniques have been researched through decades of AFC experiments in laboratories, wind tunnels and small-scale aircraft. [1] https://www.aerospacetestinginternational.com/features/is-active-flow-control-the-next-step-in-flight-controls.html https://www.aerospacetestinginternational.com/features/is-ac...
- u320 3y ago
  The shielding requirements would make a Helion-type reactor a bit difficult.
  - arethuza 3y ago
    Given the not terribly successful attempts to use fission reactors in aircraft I did wonder about this. Apparently Helion's approach is "mostly aneutronic fusion" - still means that 5% of power output as fast neutrons - which I suspect is probably too much to shield from in an aircraft (mind you I am not a nuclear or aircraft engineer so what do I know!). Thinking about the fictional Helios in the excellent For All Mankind does make me wonder if it might work in a spacecraft!
  - puzzlingcaptcha 3y ago
    Would you need as much shielding in an unmanned craft?
    - noitpmeder 3y ago
      Probably unless you want the entire thing to end up unmaintainable/untouchable by anything other than a hardened robot.
bell-cot 3y ago
The title's "no moving control surfaces" (both on HN and the DARPA site) contradicts the article itself: > The X-65 will be built with two sets of control actuators – traditional flaps and rudders as well as AFC effectors embedded across all the lifting surfaces. This will both minimize risk and maximize the program’s insight into control effectiveness. The plane’s performance with traditional control surfaces will serve as a baseline; successive tests will selectively lock down moving surfaces, using AFC effectors instead. > “The X-65 conventional surfaces are like training wheels to help us understand how AFC can be used in place of traditional flaps and rudders,” said Wlezien. “We’ll have sensors in place to monitor how the AFC effectors’ performance compares with traditional control mechanisms, and these data will help us better understand how AFC could revolutionize both military and commercial craft in the future.” Was anyone else's first reaction to DARPA's "Artist's Rendering" to wonder "what new kiddie cartoon show is that from?"
- prox 3y ago
  I guess the goal is no moving control surfaces, but this prototype has both to understand and compare, that is how I read the article at least. The rendering could be straight from Thunderbirds if you give it a green lick of paint!
  - ceejayoz 3y ago
    Reminds me of https://en.wikipedia.org/wiki/Northrop_Tacit_Blue https://en.wikipedia.org/wiki/Northrop_Tacit_Blue a bit.
- ceejayoz 3y ago
  What contradiction? The prototype has both types of control surface. It’s for testing the new tech; you don’t want it uncontrollable if something goes wrong with the new stuff.
  - bell-cot 3y ago
    [facepalm/] It was a reasonable design decision to put both types of controls on the prototype. But if I put chocolate chips in a cookie, claim that the cookie is chocolate-free, and then (when called on it) explain that the chocolate chips were only needed to make it taste good, while working on my cookie recipes - I still have lied.
mikewarot 3y ago
The term Active Flow Control encompasses a surprisingly wide array of techniques [1]. Most of them are far more subtle that a Harrier like vectoring of exhaust gas. Personally I'm a fan of "Electrically powered plasma actuators" which can use a high voltage AC source to alter how well the airflow sticks to the wing, and actively reduce drag. Here's some info I read about 2 decades ago on that approach[2] There were open source experiments with high voltage AC and lamp cord wire ("zip cord") in the year 2000.[3] The more time goes on, the more stuff I see as "leading edge" that I read about 20 years ago. ;-) [1] https://www.aerospacetestinginternational.com/features/is-active-flow-control-the-next-step-in-flight-controls.html https://www.aerospacetestinginternational.com/features/is-ac... [2] http://jlnlabs.online.fr/plasma/html/s_gdpthr1.htm http://jlnlabs.online.fr/plasma/html/s_gdpthr1.htm [3] http://jlnlabs.online.fr/plasma/html/s_gdp.htm http://jlnlabs.online.fr/plasma/html/s_gdp.htm
- Steve44 3y ago
  > Most of them are far more subtle that a Harrier like vectoring of exhaust gas. The Harrier has a number of bleed air reaction nozzles dotted around the aircraft so it can be controlled whilst hovering. The vectored thrust is just for the main "drive", these nozzles replace the control surfaces at hover speeds. https://xplanereviews.com/index.php?/forums/topic/965-aircraft-review-mcdonnell-douglas-harrier-av-8b-by-x-trident/ https://xplanereviews.com/index.php?/forums/topic/965-aircra... > For me the significant area was the flight "puffer" small reaction nozzles that are the most important and the most ingenious aspect of the Harrier. It is actually quite easy to support any aircraft on a downward thrust of gases, and even here with the clever engine mounted vector nozzles... the real trick was in actually controlling the aircraft in the air. The Harrier has a unique system of engine bleed that directs air to the various reaction nozzles...
user3939382 3y ago
I used to think these projects were cool and even strategized on bidding on some of them. Now I just see another face of the military industrial complex that’s destroyed our democracy and I don’t care what they’re making. The “defense” industry makes me sick. This is like someone’s destroying my home and stops to show me how cool their hammer is.
- H8crilA 3y ago
  You should write a book, it's going to be a massive success.
- 1234letshaveatw 3y ago
  destroyed some, preserved others
corn13read2 3y ago
Auto industry already realized this doesn't work, maybe ai will make it moot.
Eddy_Viscosity2 3y ago
It says it reduces complexity, but does it? You still need the compressed air systems and and the control systems needed to inject exactly the right amount of air in the right places for the right amount of time. Sounds complex to me.
- Tuna-Fish 3y ago
  Some kinds of complexity are more fragile and easier to maintain than others. Active flow control systems benefit from the fact that any individual valve has very little effect on the flight characteristics of the aircraft, making achieving high redundancy much easier. Also, the moving parts will be much smaller, and so easier to replace and maintain.
- 4gotunameagain 3y ago
  Keep in mind that traditional control surfaces need the complex hydraulic systems that already do something similar, so if there are other benefits to be gained (efficiency, post stall manoeuvrability) by the lack of the movable flap, it seems well worth a try.
aquaphile 3y ago
Many DARPA projects over the years have approached similar X-65 design goals of increased flight control, modularity/redundancy. One of my favorites was Pulse Ejector Thrust Augmentation (PETA). Wired's sensational take on it is at https://www.wired.com/2011/07/boeings-millennium-falcon-floats-using-nazi-technology/ https://www.wired.com/2011/07/boeings-millennium-falcon-floa... One of the big benefits of X-65/PETA/et al is generating increased lift at takeoff and landing without the wings. One can think of it as a hybrid or multi-lift design. The wings for flight are smaller since it is augmented with other controlled lift/thrust, and this allows the aircraft to be lighter and smaller since it doesn't need huge wings for the low-speed takeoff and landing.
- pdonis 3y ago
  > huge wings for the low-speed takeoff and landing For military aircraft, at least, large wings aren't just for low speed takeoff and landing, they're also for greater agility and maneuverability. I'm assuming that one of the goals of this X project will be to see whether those performance characteristics can be maintained or improved.
datadrivenangel 3y ago
Having hundreds of tiny holes in the wing to release compressed air sounds mechanically too complicated. But advanced jet engines have used the same technique INSIDE THE TURBINE BLADES for ~50 years now to keep them from melting, so it probably isn't too bad if the results are good. And it may be simpler and more reliable than the existing hydraulic systems.
startupsfail 3y ago
What happens when an aircraft with these 1mm openings is flying through the clouds or freezing rain?
- bunderbunder 3y ago
  Sounds like a good question to probe with an X project.
- BriggyDwiggs42 3y ago
  Theyd be exhausting plasma right?
  - JumpCrisscross 3y ago
    > Theyd be exhausting plasma right? I don't see the word "plasma" once in the article. That said, neither de-icing nor small surface conduits are new in aviation. The J58 famously bled air overboard to disrupt a boundary layer [1]. [1] https://en.wikipedia.org/wiki/Pratt_&_Whitney_J58#/media/File:SR71_J58_Engine_Airflow_Patterns.svg https://en.wikipedia.org/wiki/Pratt_&_Whitney_J58#/media/Fil...
    - BriggyDwiggs42 3y ago
      Ah okay I think I just imagined that cause it wouldn’t make much sense anyways. Not sure why I thought I saw that.
- Aloisius 3y ago
  The openings they're pushing hot pressurized air through? Real world testing is the reason for these experimental demonstrators is it not?
deleted 3y ago
[deleted]
ExoticPearTree 3y ago
After reading the article, it seems they want to have a plane that is controlled by little thrusters that can move the airplane in the desired direction - pretty much like spacecraft is being controlled in space. I don't know how they will perform takeoffs and landings using this new system.
- sgc 3y ago
  That is not what I understood. They are not thrusters, they work by changing the profile of the airflow rather than pushing the aircraft directly, in a way similar to flaps. They would not work in space.
  - ExoticPearTree 3y ago
    I never said the plane would work in space, just that they would work like thrusters to change airplane direction. Just like a normal dual engine airplane would yaw if thrust becomes asymmetric, it could go up/down or roll just as easy if thrust is applied to push against any other surface.
    - Toutouxc 3y ago
      > they would work like thrusters to change airplane direction > if thrust is applied to push against any other surface Which, again, is not what's happening here.
    - JumpCrisscross 3y ago
      > they would work like thrusters to change airplane direction The thrusters don't push the plane. They push the boundary layer that lifts the plane. It's not incorrect to think of conventional control surfaces as tools to physically push the boundary layer around, which is ultimately the mass that impacts the prevailing wind to create lift. This is just doing that with air. Aerodynamic, not astrodynamic or ballistic.
detritus 3y ago
I'm not quite sure it's the same thing, but I many years ago had an idea for inflatable control surfaces for low-speed vehicles place of mechanical ailerons. I was in between jobs at the time and thought it might be an interesting diversion, especialyl as I've always been a bit of a plane geek. I'm sure it might've been, but after buying a few books on patenting and general design development I quickly realised I was going to be in way over my head and that my savings - grand as I thought they were at the time - would barely make a dent in development costs. Ho hum.
- mlyle 3y ago
  Playing with things on RC aircraft is a forgiving domain to prototype new ideas. But there's not a whole lot of a "low speed aircraft" market.
  - detritus 3y ago
    I more meant "not jet-powered" for 'low-speed', and this was a good twenty years ago. It's quite crazy how much RC-tech has advanced in that short span, so maybe you've got a point!
humanfromearth9 3y ago
Probably engineered by Dyson...

304 points by wolverine876 3y ago

I truly hope that same Wii sports -esque music in the video also emits while this thing shoots missiles

>by using jets of air from a pressurized source Presumably bleed air from the jet engine compressor, which means this design won't work for piston-engine propeller drones, which is the usual configuration for small non-stealth drones. I wonder where in the copyediting process this got left out, because otherwise this design would be bonkers. >Eliminating external moving parts is expected to reduce weight External moving parts, of course, since it'll have just as many valves to control the flow of bleed air as a regular hydraulic setup. I wonder what material they're making the wings out of-- bleed air is pretty hot.

christkv 3y ago
What happens when propulsion fails on this. Does not seem likely it will be able to perform a glide landing.
- AdamN 3y ago
  It's unmanned so a self-destruct mechanism is probably the straightforward solution - or disable power and use a parachute
- londons_explore 3y ago
  Backup air reservoir?
- justin66 3y ago
  It's an X plane, and it's unmanned. If propulsion fails, it will presumably crash in the desert. Some of the press on this talks about weight savings. If they're really serious about that, well... none of their flights are intended to go above Mach 0.7. Possibly they could deploy a ballistic parachute like Cirrus airplanes offer.
- sgjohnson 3y ago
  Presumably, this would be operated in hostile territory, so nobody would particularly care about it turning into a giant fireball upon crash landing. Or self-destructed when still airborne.
- deleted 3y ago
  [deleted]
boxed 3y ago
Couldn't it have just one central compressor for this air?
- londons_explore 3y ago
  I suspect it needs rather large qualities of air. Ie. Cubic meters per second. It's gotta be a modified engine that lets you extract compressed air.
  - krisoft 3y ago
    > It's gotta be a modified engine that lets you extract compressed air. That is basically a standard feature on every jet engine. It is called bleed air. https://en.wikipedia.org/wiki/Bleed_air https://en.wikipedia.org/wiki/Bleed_air
- usrusr 3y ago
  Yes? For example that central jet engine that the plane already has? Doesn't change anything about requiring additional moving parts to control where the compressed air goes and where it goes not. The goal of this entire exercise is not to expel some extra compressed air in places where previously regular outside flow happened, the goal is to control the plane by changing when and where that disturbance by extra air happens.
  - Toutouxc 3y ago
    To be fair, the original comment was about piston engine powered aircraft. These would really need either a separate compressor/blower or a complicated modification of the exhaust system.
    - usrusr 3y ago
      True, must have missed that, deep branches on higher rated sibling comments. And at the time when I did skim the actual grandparent, I dismissed the part about piston because I don't believe that any of the suspected benefits of this pressed air disturbance control scheme could ever be meaningful in the realm of piston-engine drones. Control surfaces are cheap.
LargeTomato 3y ago
> Presumably bleed air from the jet engine compressor. We don't know that and this is the very first prototype so it could absolutely evolve over time. > Which means this design won't work for piston engine propeller drones In its current, nascent configuration where we are prototyping a new technology using a testbed platform, maybe. Again, this is not a commercial-ready product it's a prototype. > Which is the usual configuration for small non-stealth drones So this prototype doesn't fit on a $10 quad copter so it's... Flawed? > I wonder where in the copyediting process this got left out Prototype. > Because otherwise this design would be bonkers. More or less bonkers than dismissing a completely novel aviation technology before it's even gotten off the ground? More or less bonkers than dismissing a completely novel technology because it doesn't work for your one specific hypothetical use case?
- rmccue 3y ago
  > So this prototype doesn't fit on a $10 quad copter so it's... Flawed? I didn’t read the original as meaning non-military drones, rather non-stealth military drones. For example, to the OP’s point, the Predator drone is powered by a piston engine - I’m not overly familiar with other military drones, but stands to reason other UAVs use similar tech.
  - lupusreal 3y ago
    They're talking about this prototype doing mach 0.7, so it's a safe bet they intend it to have a turbofan. That's much faster than a MQ-1/MQ-9 and also faster than a (turbofan) MQ-20. Dismissing this design because it requires a jet engine just seems bizarre. Like okay, it doesn't work with piston props... so what?
- adrian_b 3y ago
  > We don't know that and this is the very first prototype so it could absolutely evolve over time. The high-pressure air must come from a compressor, either a separate compressor or the jet engine compressor. Obviously it is much cheaper and much more compact to use bleed air from the jet engine compressor, than to include a second compressor, only for maneuvering. On an aircraft without a turbo-engine adding a compressor would increase the cost and the energy consumption a lot in comparison with the traditional methods of steering the aircraft, so it is not advantageous. However this method without control surfaces should also be usable with turboprop engines, not only with jet engines.
fidotron 3y ago
BAE built a much smaller test UAV of the same idea in 2010 https://en.wikipedia.org/wiki/BAE_Systems_Demon https://en.wikipedia.org/wiki/BAE_Systems_Demon which was indeed a mixture of bleed air and exhaust.
krisoft 3y ago
> bleed air is pretty hot. Initially yes. But then it can be cooled by expanding it or mixing it with cold air. This is pretty routine. After all the air you breath on airlines is coming from bleed air too. > it'll have just as many valves to control the flow of bleed air as a regular hydraulic setup Sure, but that's not the heavy stuff. The fact that bits of the wing has to be independently movable means that it has to be much heavier. If the whole wing would be just one piece you could presumably support it more efficiently.
deleted 3y ago
[deleted]
ranger207 3y ago
There's been a bunch of piston engine planes with hydraulic pumps; I don't think a pneumatic one will be much more difficult
Aloisius 3y ago
> Presumably bleed air from the jet engine compressor It appears to come from an auxiliary power unit. https://youtu.be/G_jhcqGjUww?t=43 https://youtu.be/G_jhcqGjUww?t=43

Lastodon 3y ago

Title is false. The plane has moving control surfaces.

boxed 3y ago
Only to compare to, and as backup when they are still unsure about the flight performance of the new system.
- justin66 3y ago
  A design in this vein might want to keep moving control surfaces locked down in all but extraordinary circumstances: spin recovery or flameout. Maximum g turns? For that matter, it's not crazy to think that they'd want to keep the moving control surfaces available for takeoff and landing.
  - usrusr 3y ago
    I went through this idea in my head reading the sibling speculations about civilian use and discarded the idea: when you have the control surfaces, there's no cost in using them. In terms of aerodynamic inefficiency I'd expect it to be a tie at best, both are disturbances that make the flow worse to achieve an effect. If they do discover a way to improve aerodynamic qualities with compressed air, chances are civilian aircraft would just switch it on whenever it helps and keep control going through conventional control surfaces just like before.

foota 3y ago

It's not mentioned in the article, but I wonder if part of this is about stealth. I imagine the moving control planes might create additional cross section vs not having them?

londons_explore 3y ago
It sounds like this option could let you make the wings and tail of the plane metal-free, which is good for hiding from radar
- Terr_ 3y ago
  > the wings and tail of the plane metal-free At some point that's like trying to make someone invisible by making their skin--and only their skin--transparent. It'll backfire when all the twisty complicated still-important stuff on the inside stands out even more.
  - superb_dev 3y ago
    What is the resolution of modern radar? The important core might not be big enough to see
    - Vecr 3y ago
      It's not about resolution, you can see stars easily that your eyes can't resolve as a disk. It's about magnitude.
  - c22 3y ago
    With this scheme it seems you could concentrate all the twisty complicated stuff to a small area in the body of the plane and use rubber hoses to deliver the air to the control surfaces.
    - Terr_ 3y ago
      Internal space of wings is often used for storing fuel. I'm not sure if there are any studies on how well modern radar could detect sloshy blobs of kerosene flying through the sky. (Inside totally radar-transparent containers.)

cm2187 3y ago

So if the engine shuts down you lose control of the plane? Hope they will install ejection seats if it is to be used in an airliner...

foota 3y ago
It's DARPA, its probably intended for a drone.
- cm2187 3y ago
  Not sure, it says "...help us better understand how AFC could revolutionize both military and commercial craft in the future"
  - wiz21c 3y ago
    I'd venture to say that most of the airline transport is goods, not people. So an unmanned plane would be OK...
    - cm2187 3y ago
      Even if it's cargo and unmanned, you can't let massive objects full of fuel that become uncontrollable if the engine fails fly over populated areas.
      - bbor 3y ago
        Shouldn’t*. We let massive objects full of fuel that become uncontrollable if the engine fails drive through populated areas, and by the common clay of the west no less! Economics trumps safety, it’s all about the trade off our society is willing to make. And our society is willing to make some pretty huge ones. I for one would not be worried about a slightly higher possibility of getting hit by a falling plane, unless this system was provably very unreliable or something.
      - baybal2 3y ago
        [dead]

LargeTomato 3y ago

Darpa is testing a completely novel type of flight control and all these HN comments are just nitpicking irrelevant things, missing the forest through the trees, and saying "it won't work on propeller drones". The quality of discussion on this website is abysmal.

deleted 3y ago
[deleted]
robertlagrant 3y ago
Honestly, the quality is only lowered by this comment. You already replied to the drones thing. Writing a second, ranting, comment at the top level scaling up that comment to represent all of HN discussion of all time is just a bit silly.
- LargeTomato 3y ago
  Anything about foreign policy, IR, and aerospace is reddit-tier. Probably more subjects too but they are out of my area of expertise.
  - mdhb 3y ago
    Add in anything that’s even remotely related to intelligence or defence which is typically just filled with qanon style nonsense. I’ve noticed it for years as well, you aren’t wrong.
    - bombcar 3y ago
      Except for some very specific knowledgeable posters, the vast majority of all Internet comments could be replaced by a LLM. Including this one. The key is to not post them yourself and to let the good ones shine.
      - ChainOfFools 3y ago
        I don't know, I think there needs to be some form of unambiguous BS pushback signal, a gradient that starts with minimal intrusion on discussion along the lines of "people are starting to notice that some of us are talking past our pay grade." Not saying anything at all amounts to an endorsement of penalty free bullshiting, and after enough of this the hard-won cultural expectations start to shift about what constitutes acceptable participation. There's a spectrum between Reddit on one end, and the typical IRC channel fiefdom with its mod-permissioned voicing, invisible banhammer tripwires, and admonitions to LuRK MoAR, on the other, and I think HN is in a sweet spot/zone somewhere between those extremes, but perhaps might need an adjustment in the direction of the latter. Downvoting/flagging somewhat furnishes this signalling, but it's too ambiguous of a signal and is often abused by people who simply want to suppress information that is perfectly valid but not to their liking. This is where a slashdot type of lightly sentiment-coded moderation system really may be worth bringing back into fashion.

wolverine876 3y ago

From another article linked in a comment: "We have tried to conceive a demonstrator that can accommodate all types of active flow control in a diverse range of aircraft planforms and uses for AFC, whether for high-lift, flight control or other objectives,” says Aurora’s government programs lead, Graham Drozeski. https://www.aerospacetestinginternational.com/features/is-active-flow-control-the-next-step-in-flight-controls.html https://www.aerospacetestinginternational.com/features/is-ac...

paulsutter 3y ago

Active flow control (AFC) can be pneumatic or electric Given a small Helion-type fusion reactor, crazy aircraft will be possible from [1]: > Electric AFC techniques use arrays of electrodes to discharge aerodynamic or electrical pulses to locally alter airflow. Effectors called synthetic jets – millimeter-wide openings in the aircraft surface that open into centimeter-wide cavities with diaphragms – rely on rapid voltage pulses to make diaphragms oscillate inward or outward, creating airflow sucking or blowing effects, much like a human lung. > Electrically powered plasma actuators discharge pulses of electricity into the air through electrodes. The heat from the electricity turns the air into plasma, thermally altering flow vectors. All of these techniques have been researched through decades of AFC experiments in laboratories, wind tunnels and small-scale aircraft. [1] https://www.aerospacetestinginternational.com/features/is-active-flow-control-the-next-step-in-flight-controls.html https://www.aerospacetestinginternational.com/features/is-ac...

u320 3y ago
The shielding requirements would make a Helion-type reactor a bit difficult.
- arethuza 3y ago
  Given the not terribly successful attempts to use fission reactors in aircraft I did wonder about this. Apparently Helion's approach is "mostly aneutronic fusion" - still means that 5% of power output as fast neutrons - which I suspect is probably too much to shield from in an aircraft (mind you I am not a nuclear or aircraft engineer so what do I know!). Thinking about the fictional Helios in the excellent For All Mankind does make me wonder if it might work in a spacecraft!
- puzzlingcaptcha 3y ago
  Would you need as much shielding in an unmanned craft?
  - noitpmeder 3y ago
    Probably unless you want the entire thing to end up unmaintainable/untouchable by anything other than a hardened robot.

bell-cot 3y ago

The title's "no moving control surfaces" (both on HN and the DARPA site) contradicts the article itself: > The X-65 will be built with two sets of control actuators – traditional flaps and rudders as well as AFC effectors embedded across all the lifting surfaces. This will both minimize risk and maximize the program’s insight into control effectiveness. The plane’s performance with traditional control surfaces will serve as a baseline; successive tests will selectively lock down moving surfaces, using AFC effectors instead. > “The X-65 conventional surfaces are like training wheels to help us understand how AFC can be used in place of traditional flaps and rudders,” said Wlezien. “We’ll have sensors in place to monitor how the AFC effectors’ performance compares with traditional control mechanisms, and these data will help us better understand how AFC could revolutionize both military and commercial craft in the future.” Was anyone else's first reaction to DARPA's "Artist's Rendering" to wonder "what new kiddie cartoon show is that from?"

prox 3y ago
I guess the goal is no moving control surfaces, but this prototype has both to understand and compare, that is how I read the article at least. The rendering could be straight from Thunderbirds if you give it a green lick of paint!
- ceejayoz 3y ago
  Reminds me of https://en.wikipedia.org/wiki/Northrop_Tacit_Blue https://en.wikipedia.org/wiki/Northrop_Tacit_Blue a bit.
ceejayoz 3y ago
What contradiction? The prototype has both types of control surface. It’s for testing the new tech; you don’t want it uncontrollable if something goes wrong with the new stuff.
- bell-cot 3y ago
  [facepalm/] It was a reasonable design decision to put both types of controls on the prototype. But if I put chocolate chips in a cookie, claim that the cookie is chocolate-free, and then (when called on it) explain that the chocolate chips were only needed to make it taste good, while working on my cookie recipes - I still have lied.

mikewarot 3y ago

The term Active Flow Control encompasses a surprisingly wide array of techniques [1]. Most of them are far more subtle that a Harrier like vectoring of exhaust gas. Personally I'm a fan of "Electrically powered plasma actuators" which can use a high voltage AC source to alter how well the airflow sticks to the wing, and actively reduce drag. Here's some info I read about 2 decades ago on that approach[2] There were open source experiments with high voltage AC and lamp cord wire ("zip cord") in the year 2000.[3] The more time goes on, the more stuff I see as "leading edge" that I read about 20 years ago. ;-) [1] https://www.aerospacetestinginternational.com/features/is-active-flow-control-the-next-step-in-flight-controls.html https://www.aerospacetestinginternational.com/features/is-ac... [2] http://jlnlabs.online.fr/plasma/html/s_gdpthr1.htm http://jlnlabs.online.fr/plasma/html/s_gdpthr1.htm [3] http://jlnlabs.online.fr/plasma/html/s_gdp.htm http://jlnlabs.online.fr/plasma/html/s_gdp.htm

Steve44 3y ago
> Most of them are far more subtle that a Harrier like vectoring of exhaust gas. The Harrier has a number of bleed air reaction nozzles dotted around the aircraft so it can be controlled whilst hovering. The vectored thrust is just for the main "drive", these nozzles replace the control surfaces at hover speeds. https://xplanereviews.com/index.php?/forums/topic/965-aircraft-review-mcdonnell-douglas-harrier-av-8b-by-x-trident/ https://xplanereviews.com/index.php?/forums/topic/965-aircra... > For me the significant area was the flight "puffer" small reaction nozzles that are the most important and the most ingenious aspect of the Harrier. It is actually quite easy to support any aircraft on a downward thrust of gases, and even here with the clever engine mounted vector nozzles... the real trick was in actually controlling the aircraft in the air. The Harrier has a unique system of engine bleed that directs air to the various reaction nozzles...

user3939382 3y ago

I used to think these projects were cool and even strategized on bidding on some of them. Now I just see another face of the military industrial complex that’s destroyed our democracy and I don’t care what they’re making. The “defense” industry makes me sick. This is like someone’s destroying my home and stops to show me how cool their hammer is.

H8crilA 3y ago
You should write a book, it's going to be a massive success.
1234letshaveatw 3y ago
destroyed some, preserved others

corn13read2 3y ago

Auto industry already realized this doesn't work, maybe ai will make it moot.

Eddy_Viscosity2 3y ago

It says it reduces complexity, but does it? You still need the compressed air systems and and the control systems needed to inject exactly the right amount of air in the right places for the right amount of time. Sounds complex to me.

Tuna-Fish 3y ago
Some kinds of complexity are more fragile and easier to maintain than others. Active flow control systems benefit from the fact that any individual valve has very little effect on the flight characteristics of the aircraft, making achieving high redundancy much easier. Also, the moving parts will be much smaller, and so easier to replace and maintain.
4gotunameagain 3y ago
Keep in mind that traditional control surfaces need the complex hydraulic systems that already do something similar, so if there are other benefits to be gained (efficiency, post stall manoeuvrability) by the lack of the movable flap, it seems well worth a try.

aquaphile 3y ago

Many DARPA projects over the years have approached similar X-65 design goals of increased flight control, modularity/redundancy. One of my favorites was Pulse Ejector Thrust Augmentation (PETA). Wired's sensational take on it is at https://www.wired.com/2011/07/boeings-millennium-falcon-floats-using-nazi-technology/ https://www.wired.com/2011/07/boeings-millennium-falcon-floa... One of the big benefits of X-65/PETA/et al is generating increased lift at takeoff and landing without the wings. One can think of it as a hybrid or multi-lift design. The wings for flight are smaller since it is augmented with other controlled lift/thrust, and this allows the aircraft to be lighter and smaller since it doesn't need huge wings for the low-speed takeoff and landing.

pdonis 3y ago
> huge wings for the low-speed takeoff and landing For military aircraft, at least, large wings aren't just for low speed takeoff and landing, they're also for greater agility and maneuverability. I'm assuming that one of the goals of this X project will be to see whether those performance characteristics can be maintained or improved.

datadrivenangel 3y ago

Having hundreds of tiny holes in the wing to release compressed air sounds mechanically too complicated. But advanced jet engines have used the same technique INSIDE THE TURBINE BLADES for ~50 years now to keep them from melting, so it probably isn't too bad if the results are good. And it may be simpler and more reliable than the existing hydraulic systems.

startupsfail 3y ago

What happens when an aircraft with these 1mm openings is flying through the clouds or freezing rain?

bunderbunder 3y ago
Sounds like a good question to probe with an X project.
BriggyDwiggs42 3y ago
Theyd be exhausting plasma right?
- JumpCrisscross 3y ago
  > Theyd be exhausting plasma right? I don't see the word "plasma" once in the article. That said, neither de-icing nor small surface conduits are new in aviation. The J58 famously bled air overboard to disrupt a boundary layer [1]. [1] https://en.wikipedia.org/wiki/Pratt_&_Whitney_J58#/media/File:SR71_J58_Engine_Airflow_Patterns.svg https://en.wikipedia.org/wiki/Pratt_&_Whitney_J58#/media/Fil...
  - BriggyDwiggs42 3y ago
    Ah okay I think I just imagined that cause it wouldn’t make much sense anyways. Not sure why I thought I saw that.
Aloisius 3y ago
The openings they're pushing hot pressurized air through? Real world testing is the reason for these experimental demonstrators is it not?

deleted 3y ago

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ExoticPearTree 3y ago

After reading the article, it seems they want to have a plane that is controlled by little thrusters that can move the airplane in the desired direction - pretty much like spacecraft is being controlled in space. I don't know how they will perform takeoffs and landings using this new system.

sgc 3y ago
That is not what I understood. They are not thrusters, they work by changing the profile of the airflow rather than pushing the aircraft directly, in a way similar to flaps. They would not work in space.
- ExoticPearTree 3y ago
  I never said the plane would work in space, just that they would work like thrusters to change airplane direction. Just like a normal dual engine airplane would yaw if thrust becomes asymmetric, it could go up/down or roll just as easy if thrust is applied to push against any other surface.
  - Toutouxc 3y ago
    > they would work like thrusters to change airplane direction > if thrust is applied to push against any other surface Which, again, is not what's happening here.
  - JumpCrisscross 3y ago
    > they would work like thrusters to change airplane direction The thrusters don't push the plane. They push the boundary layer that lifts the plane. It's not incorrect to think of conventional control surfaces as tools to physically push the boundary layer around, which is ultimately the mass that impacts the prevailing wind to create lift. This is just doing that with air. Aerodynamic, not astrodynamic or ballistic.

detritus 3y ago

I'm not quite sure it's the same thing, but I many years ago had an idea for inflatable control surfaces for low-speed vehicles place of mechanical ailerons. I was in between jobs at the time and thought it might be an interesting diversion, especialyl as I've always been a bit of a plane geek. I'm sure it might've been, but after buying a few books on patenting and general design development I quickly realised I was going to be in way over my head and that my savings - grand as I thought they were at the time - would barely make a dent in development costs. Ho hum.

mlyle 3y ago
Playing with things on RC aircraft is a forgiving domain to prototype new ideas. But there's not a whole lot of a "low speed aircraft" market.
- detritus 3y ago
  I more meant "not jet-powered" for 'low-speed', and this was a good twenty years ago. It's quite crazy how much RC-tech has advanced in that short span, so maybe you've got a point!

humanfromearth9 3y ago

Probably engineered by Dyson...