13 ms·

An F-22 test pilot on the Raptor's flight control system

240 points by clouddrover 6y ago

fermienrico 6y ago
Why do we time and again see this horrible blog spam, that is The Drive magazine? All they do is keep padding the prose until it is 8-10 paragraphs while paraphrasing and quoting the original source. Stratechery does that as well, but also provides original commentary and insight. The Drive is a terrible source of information. Just link to straight to Youtube: https://www.youtube.com/watch?v=Evhrk5tY-Yo https://www.youtube.com/watch?v=Evhrk5tY-Yo
- avalys 6y ago
  I find The Drive's content on military and defense news to be pretty valuable and distinctive. Even if they're just an aggregator (which honestly doesn't seem the case to me, at least in this domain), they're aggregating from sources I wouldn't think to look at myself.
- t-writescode 6y ago
  That is probably where they found the YouTube video in the first place, and they wanted to relay that part and give original citation.
- decasteve 6y ago
  And straight to the course: https://ocw.mit.edu/courses/aeronautics-and-astronautics/16-687-private-pilot-ground-school-january-iap-2019/ https://ocw.mit.edu/courses/aeronautics-and-astronautics/16-...
- clouddrover 6y ago
  The video's over an hour long. The Drive article provides a useful summary so you can decide if you want to watch the video, which is why I linked to it.
- ardit33 6y ago
  They gave a good summary, and links to the video, which is really interesting. What do you want more? Not everyone has 1hr to spend to watch the whole thing.
- Spooky23 6y ago
  Why do we have hacker news? Real nerds read the whole internet every day.
  - mirimir 6y ago
    > Real nerds read the whole internet every day. Hey, they have their AI read it all, and prepare a precis :)
- avs733 6y ago
  I tend to agree..it's a style thing. It has been when the lead author has written for other sites as well. I think it is subtly different from blog spam in that those pargraphs provide a ton of valuable information, but in an attempt to be detailed and precise can become redundant and a bit of a slog. Tyler has an enormous amount of knowledge and...sometimes overexplains or over introduces the simple point he is trying to make for my tastes. It seems to assume every article reader starts from absolutely zero knowledge.
- exhilaration 6y ago
  While I generally agree with your sentiment, I didn't watch the video and was satisfied reading summary in the linked article.
  - sandworm101 6y ago
    The article almost made me not watch the video. It is poorly written, by someone not versed in aviation terminology. Much of what said of "raptor pilots" is in fact true of all fighters. And some of the facts are so awkwardly worded that they are borderline incorrect. For instance, the F-22 does not fly at 60-65,000 feet. That is its service ceiling, its maximum possible altitude.
    - Aeolun 6y ago
      > For instance, the F-22 does not fly at 60-65,000 feet. That is its service ceiling, its maximum possible altitude. So it flies at 60-65k feet. I don’t see how that is wrong? If a pilot wants to keep cruising along at that altitude it is apparently possible, even if they might not generally do so.
      - mirimir 6y ago
        Actually, TFA says: > ... Gordon notes the aircraft flies at altitudes from 60,000-65,000 feet.
        sandworm101 6y ago
        Which would make landings rather difficult.
        mirimir 6y ago
        My thought exactly :)
jcims 6y ago
This is an amazing talk. Somebody pointed it out in the YouTube comments, watch how he handles the little toy Cessna versus the toy F22. :)
SECProto 6y ago
In case anyone else is confused by the title, F-22 and Raptor both refer to the same thing.
sandworm101 6y ago
>> is needed to make the Raptor's super maneuverability a reality. The term is "Supermaneuverability"... all one word. This is characterized as post-stall, sometimes called "non-aerodynamic" controlled flight. In short, it means the aircraft remains under pilot control even after the flow has separated from the wing (aka a stall). The 22 is not considered supermaneuverable by many. It can use thrust vectoring and some fly-by-wire tricker to ape supermaneuverability but it pales in comparison to many russian aircraft. The 22's wing becomes very unpredictable in stall, hence the need for all the fly by wire. It was meant for flying fast in a strait line, and for stealth. It was never meant for things like Kobras or Kulbits. That it could eventually do them was an afterthought. The Russian aircraft have wings designed for slow speed/high AOA maneuverability. https://en.wikipedia.org/wiki/Kulbit https://en.wikipedia.org/wiki/Kulbit https://www.youtube.com/watch?v=Jks6TTFsglk https://www.youtube.com/watch?v=Jks6TTFsglk Kulbit / Chakra at about 05:20 and again at 06:20. Note how slow/tight the show is. An f-22 could never perform repeated maneuvers like this in such a confined space.
- scarier 6y ago
  To add on, supermaneuverabillity looks really cool and is an impressive technical achievement for sure, but its utility in combat (at least for the time being) is likely low to negative. Among other reasons, the more players in a fight, the less anyone can afford to sell all their energy for a shot opportunity--even if it works, it leaves them extremely vulnerable.
  - stouset 6y ago
    This 100%. While really cool demonstrations, the utility of these in a fight is virtually nonexistent. Any air-to-air engagements these days are inevitably BVR (beyond visual range) encounters, where aircraft fire missiles at one-another from extreme ranges. This type of maneuverability has no use whatsoever in such a scenario. If all of the long-range missiles fail to neutralize one side of the other and both forces opt to continue the engagement, you get to WVR (within visual range) where infrared missiles and—once those are spent—guns are employed. There could be opportunities here where such a trick might be useful, but only in a 1v1 scenario. For any case where you might have two or more enemies to deal with, such an abrupt loss of energy is suicide. And if you’re on the side with superior numbers, the odds are overwhelmingly in your favor with little chance of you being defensive in the first place. And in the 1v1 scenario, modern infrared missiles like the AIM-9x (which are effective even when launched at frankly ridiculous off-boresight angles) make such a maneuver suicide as well. So it might, might be useful if: both sides empty their long/medium-range radar-guided missiles at one-another, only two combatants remain, neither decides to bug out, the aggressor empties their IR missiles unsuccessfully, and the defensive craft is imminently going to be within the weapon employment zone for the bandit’s cannon… then this might be a Hail Mary to force the aggressor to overshoot so you can turn the tables. But having bled all your energy, you’re going to get at most one shot before you’re back to simply trying to survive.
blunte 6y ago
The F-22 is such a marvel. I really wonder why the F-35 is plagued with so many systemic problems since it should be no more complex (and has the F-22 as an example for many of its own requirements).
- Causality1 6y ago
  The F-22 is designed first and foremost as an air superiority fighter. The F-35 was intended to replace half a dozen wildly different aircraft with a single plane. That was a horrible idea right from the outset.
  - terlisimo 6y ago
    According to one AF general, the purpose of the F-35 is "to spend money". So in that aspect it is performing admirably :) https://www.youtube.com/watch?v=ba63OVl1MHw https://www.youtube.com/watch?v=ba63OVl1MHw
    - credit_guy 6y ago
      This is such a silly conspiracy theory. It may make sense for US congressmen to lobby for pork in their districts, but why would the Israeli Air Force invest in defective machines? [1] https://en.wikipedia.org/wiki/Lockheed_Martin_F-35_Lightning_II_Israeli_procurement#2019 https://en.wikipedia.org/wiki/Lockheed_Martin_F-35_Lightning...
      - projektfu 6y ago
        Their existing fleet of F-15 and F-16 fighters is getting pretty old. I have been a “fan” of the F-16 since I was a kid and I’m in my 40s now. I think for political reasons they don’t have access to Russian or European aircraft and they probably don’t want Chinese ones. This is the first new fighter we have available to them.
        ip26 6y ago
        They can't buy F-22's?
canada_dry 6y ago
As an aside I thought the prof's comment regarding having commercial co-pilots flying along with the pilot - via remote control - was interesting. It would seem to me a logical first step to someday having fully remote controlled aircraft flying passengers (which as the F22 pilot notes - is every airline's dream).
- CryptoBanker 6y ago
  I would imagine that cargo planes will have to safely fly on fully remote controlled aircraft for a number of years before airlines start thinking about opening themselves up to such liability...
raverbashing 6y ago
So someone picked up a comment on HN that had this video (or maybe through some other path) and turned it into an article Interesting
krisoft 6y ago
What I’m really interested is how do you engineer such a software system? I bet they have a simulation system, how do you validate that? What type of tests do they have? How do they iterate when a deficiency is found? How do the team looks like? Is it 10 geniouses keeping the whole system in their heads or 4000 replacable cogs? If the second how do you make sure they all act in coordination?
- bob1029 6y ago
  In terms of how you would abstractly model this type of engineering problem, I would start with state space representation: https://en.wikipedia.org/wiki/State-space_representation https://en.wikipedia.org/wiki/State-space_representation
- bamboozled 6y ago
  It's "Geniuses", not sure why, it's just one word I feel strongly about being spelled properly.
- richardowright 6y ago
  They do have a very comprehensive simulation system with a large part of the work being done at Dobbins Air Force Base just outside of Atlanta. From what I understand, the team is quite small (<10).
- icegreentea2 6y ago
  Aerospace in general is all about "document document document", and "process process process". There's this classic article about programming for the space shuttle (https://www.fastcompany.com/28121/they-write-right-stuff https://www.fastcompany.com/28121/they-write-right-stuff) that probably has reasonable parallels to how the raptor software was written. These approaches aren't problem free of course. They're definitely slow, and can appear to be inefficient depending on your frame of reference and constraints. My experience is in medtech which has similar ideas (but again obviously isn't the exact same). Ultimately all simulations used to prove that the software is working correctly are supposed to be validated (either in part or in whole) by some sort of real testing. The most expensive/real version of that is when they go off and do real test flights (or in medtech, when we go and do stuff on real people). The type of tests of they have is probably "all types of tests". You pick the right set of tests to test your software components at the scale and detail required, while finding ways to validate the assumptions you made along the way. For example, maybe you have a pure function that takes pitot tube measurements to generate air speed. You could test that function with something like a unit test, and then back it up with another set of test cases (integration or system or whatever) that show that the function is being called correctly in all cases. Every company/project will have their own Change Control process and defect resolution process defined. Typically they consist of someone reporting a defect, some sort of investigation into the defect (determining rate of occurrence, root cause if able, estimating the severity of the defect), which then gets fed into some sort of risk based problem solving algorithm to determine if an immediate fix is needed, or if there's flexibility. Then you go ahead and try to fix the thing, and when you're done, you go ahead and run more analysis to determine the scope of retest you need to do. If you're lucky, everything is self contained within the "pure software" part of your project and the "worst thing" that can happen is you have to re-run the whole software test suite. If you're not lucky, the change interacts with non-software components in ways that cannot be safely mocked out, and you have to add some kind of real world testing. I think most places lean more towards replaceable cogs - that is the whole point of all of this process and documentation. It's to minimize the overall risk of the project (which isn't the same thing as maximizing benefit). It's hard to minimize risk while requiring super top tier talent.
Shivetya 6y ago
The level of automation leads one to believe it is not inconceivable there will be versions without a cockpit with even greater flight capabilities. While many can be seen as making it easier on the human pilot conversely you can see it as making it easier to validate the automation by having a human as a backup.
ape4 6y ago
Its cool but would be nice to spend the billions on peaceful activities
iooi 6y ago
Around 19:30 he gets the movement of ailerons wrong, in case anyone else was confused by that. When turning right, the left aileron goes down and the right aileron goes up. https://sites.google.com/site/thebasicsofaviation/rudder-empennage-and-ailerons https://sites.google.com/site/thebasicsofaviation/rudder-emp...
- deleted 6y ago
  [deleted]

240 points by clouddrover 6y ago

Why do we time and again see this horrible blog spam, that is The Drive magazine? All they do is keep padding the prose until it is 8-10 paragraphs while paraphrasing and quoting the original source. Stratechery does that as well, but also provides original commentary and insight. The Drive is a terrible source of information. Just link to straight to Youtube: https://www.youtube.com/watch?v=Evhrk5tY-Yo https://www.youtube.com/watch?v=Evhrk5tY-Yo

avalys 6y ago
I find The Drive's content on military and defense news to be pretty valuable and distinctive. Even if they're just an aggregator (which honestly doesn't seem the case to me, at least in this domain), they're aggregating from sources I wouldn't think to look at myself.
t-writescode 6y ago
That is probably where they found the YouTube video in the first place, and they wanted to relay that part and give original citation.
decasteve 6y ago
And straight to the course: https://ocw.mit.edu/courses/aeronautics-and-astronautics/16-687-private-pilot-ground-school-january-iap-2019/ https://ocw.mit.edu/courses/aeronautics-and-astronautics/16-...
clouddrover 6y ago
The video's over an hour long. The Drive article provides a useful summary so you can decide if you want to watch the video, which is why I linked to it.
ardit33 6y ago
They gave a good summary, and links to the video, which is really interesting. What do you want more? Not everyone has 1hr to spend to watch the whole thing.
Spooky23 6y ago
Why do we have hacker news? Real nerds read the whole internet every day.
- mirimir 6y ago
  > Real nerds read the whole internet every day. Hey, they have their AI read it all, and prepare a precis :)
avs733 6y ago
I tend to agree..it's a style thing. It has been when the lead author has written for other sites as well. I think it is subtly different from blog spam in that those pargraphs provide a ton of valuable information, but in an attempt to be detailed and precise can become redundant and a bit of a slog. Tyler has an enormous amount of knowledge and...sometimes overexplains or over introduces the simple point he is trying to make for my tastes. It seems to assume every article reader starts from absolutely zero knowledge.
exhilaration 6y ago
While I generally agree with your sentiment, I didn't watch the video and was satisfied reading summary in the linked article.
- sandworm101 6y ago
  The article almost made me not watch the video. It is poorly written, by someone not versed in aviation terminology. Much of what said of "raptor pilots" is in fact true of all fighters. And some of the facts are so awkwardly worded that they are borderline incorrect. For instance, the F-22 does not fly at 60-65,000 feet. That is its service ceiling, its maximum possible altitude.
  - Aeolun 6y ago
    > For instance, the F-22 does not fly at 60-65,000 feet. That is its service ceiling, its maximum possible altitude. So it flies at 60-65k feet. I don’t see how that is wrong? If a pilot wants to keep cruising along at that altitude it is apparently possible, even if they might not generally do so.
    - mirimir 6y ago
      Actually, TFA says: > ... Gordon notes the aircraft flies at altitudes from 60,000-65,000 feet.
      - sandworm101 6y ago
        Which would make landings rather difficult.
        mirimir 6y ago
        My thought exactly :)

jcims 6y ago

This is an amazing talk. Somebody pointed it out in the YouTube comments, watch how he handles the little toy Cessna versus the toy F22. :)

SECProto 6y ago

In case anyone else is confused by the title, F-22 and Raptor both refer to the same thing.

sandworm101 6y ago

>> is needed to make the Raptor's super maneuverability a reality. The term is "Supermaneuverability"... all one word. This is characterized as post-stall, sometimes called "non-aerodynamic" controlled flight. In short, it means the aircraft remains under pilot control even after the flow has separated from the wing (aka a stall). The 22 is not considered supermaneuverable by many. It can use thrust vectoring and some fly-by-wire tricker to ape supermaneuverability but it pales in comparison to many russian aircraft. The 22's wing becomes very unpredictable in stall, hence the need for all the fly by wire. It was meant for flying fast in a strait line, and for stealth. It was never meant for things like Kobras or Kulbits. That it could eventually do them was an afterthought. The Russian aircraft have wings designed for slow speed/high AOA maneuverability. https://en.wikipedia.org/wiki/Kulbit https://en.wikipedia.org/wiki/Kulbit https://www.youtube.com/watch?v=Jks6TTFsglk https://www.youtube.com/watch?v=Jks6TTFsglk Kulbit / Chakra at about 05:20 and again at 06:20. Note how slow/tight the show is. An f-22 could never perform repeated maneuvers like this in such a confined space.

scarier 6y ago
To add on, supermaneuverabillity looks really cool and is an impressive technical achievement for sure, but its utility in combat (at least for the time being) is likely low to negative. Among other reasons, the more players in a fight, the less anyone can afford to sell all their energy for a shot opportunity--even if it works, it leaves them extremely vulnerable.
- stouset 6y ago
  This 100%. While really cool demonstrations, the utility of these in a fight is virtually nonexistent. Any air-to-air engagements these days are inevitably BVR (beyond visual range) encounters, where aircraft fire missiles at one-another from extreme ranges. This type of maneuverability has no use whatsoever in such a scenario. If all of the long-range missiles fail to neutralize one side of the other and both forces opt to continue the engagement, you get to WVR (within visual range) where infrared missiles and—once those are spent—guns are employed. There could be opportunities here where such a trick might be useful, but only in a 1v1 scenario. For any case where you might have two or more enemies to deal with, such an abrupt loss of energy is suicide. And if you’re on the side with superior numbers, the odds are overwhelmingly in your favor with little chance of you being defensive in the first place. And in the 1v1 scenario, modern infrared missiles like the AIM-9x (which are effective even when launched at frankly ridiculous off-boresight angles) make such a maneuver suicide as well. So it might, might be useful if: both sides empty their long/medium-range radar-guided missiles at one-another, only two combatants remain, neither decides to bug out, the aggressor empties their IR missiles unsuccessfully, and the defensive craft is imminently going to be within the weapon employment zone for the bandit’s cannon… then this might be a Hail Mary to force the aggressor to overshoot so you can turn the tables. But having bled all your energy, you’re going to get at most one shot before you’re back to simply trying to survive.

blunte 6y ago

The F-22 is such a marvel. I really wonder why the F-35 is plagued with so many systemic problems since it should be no more complex (and has the F-22 as an example for many of its own requirements).

Causality1 6y ago
The F-22 is designed first and foremost as an air superiority fighter. The F-35 was intended to replace half a dozen wildly different aircraft with a single plane. That was a horrible idea right from the outset.
- terlisimo 6y ago
  According to one AF general, the purpose of the F-35 is "to spend money". So in that aspect it is performing admirably :) https://www.youtube.com/watch?v=ba63OVl1MHw https://www.youtube.com/watch?v=ba63OVl1MHw
  - credit_guy 6y ago
    This is such a silly conspiracy theory. It may make sense for US congressmen to lobby for pork in their districts, but why would the Israeli Air Force invest in defective machines? [1] https://en.wikipedia.org/wiki/Lockheed_Martin_F-35_Lightning_II_Israeli_procurement#2019 https://en.wikipedia.org/wiki/Lockheed_Martin_F-35_Lightning...
    - projektfu 6y ago
      Their existing fleet of F-15 and F-16 fighters is getting pretty old. I have been a “fan” of the F-16 since I was a kid and I’m in my 40s now. I think for political reasons they don’t have access to Russian or European aircraft and they probably don’t want Chinese ones. This is the first new fighter we have available to them.
      - ip26 6y ago
        They can't buy F-22's?

canada_dry 6y ago

As an aside I thought the prof's comment regarding having commercial co-pilots flying along with the pilot - via remote control - was interesting. It would seem to me a logical first step to someday having fully remote controlled aircraft flying passengers (which as the F22 pilot notes - is every airline's dream).

CryptoBanker 6y ago
I would imagine that cargo planes will have to safely fly on fully remote controlled aircraft for a number of years before airlines start thinking about opening themselves up to such liability...

raverbashing 6y ago

So someone picked up a comment on HN that had this video (or maybe through some other path) and turned it into an article Interesting

krisoft 6y ago

What I’m really interested is how do you engineer such a software system? I bet they have a simulation system, how do you validate that? What type of tests do they have? How do they iterate when a deficiency is found? How do the team looks like? Is it 10 geniouses keeping the whole system in their heads or 4000 replacable cogs? If the second how do you make sure they all act in coordination?

bob1029 6y ago
In terms of how you would abstractly model this type of engineering problem, I would start with state space representation: https://en.wikipedia.org/wiki/State-space_representation https://en.wikipedia.org/wiki/State-space_representation
bamboozled 6y ago
It's "Geniuses", not sure why, it's just one word I feel strongly about being spelled properly.
richardowright 6y ago
They do have a very comprehensive simulation system with a large part of the work being done at Dobbins Air Force Base just outside of Atlanta. From what I understand, the team is quite small (<10).
icegreentea2 6y ago
Aerospace in general is all about "document document document", and "process process process". There's this classic article about programming for the space shuttle (https://www.fastcompany.com/28121/they-write-right-stuff https://www.fastcompany.com/28121/they-write-right-stuff) that probably has reasonable parallels to how the raptor software was written. These approaches aren't problem free of course. They're definitely slow, and can appear to be inefficient depending on your frame of reference and constraints. My experience is in medtech which has similar ideas (but again obviously isn't the exact same). Ultimately all simulations used to prove that the software is working correctly are supposed to be validated (either in part or in whole) by some sort of real testing. The most expensive/real version of that is when they go off and do real test flights (or in medtech, when we go and do stuff on real people). The type of tests of they have is probably "all types of tests". You pick the right set of tests to test your software components at the scale and detail required, while finding ways to validate the assumptions you made along the way. For example, maybe you have a pure function that takes pitot tube measurements to generate air speed. You could test that function with something like a unit test, and then back it up with another set of test cases (integration or system or whatever) that show that the function is being called correctly in all cases. Every company/project will have their own Change Control process and defect resolution process defined. Typically they consist of someone reporting a defect, some sort of investigation into the defect (determining rate of occurrence, root cause if able, estimating the severity of the defect), which then gets fed into some sort of risk based problem solving algorithm to determine if an immediate fix is needed, or if there's flexibility. Then you go ahead and try to fix the thing, and when you're done, you go ahead and run more analysis to determine the scope of retest you need to do. If you're lucky, everything is self contained within the "pure software" part of your project and the "worst thing" that can happen is you have to re-run the whole software test suite. If you're not lucky, the change interacts with non-software components in ways that cannot be safely mocked out, and you have to add some kind of real world testing. I think most places lean more towards replaceable cogs - that is the whole point of all of this process and documentation. It's to minimize the overall risk of the project (which isn't the same thing as maximizing benefit). It's hard to minimize risk while requiring super top tier talent.

Shivetya 6y ago

The level of automation leads one to believe it is not inconceivable there will be versions without a cockpit with even greater flight capabilities. While many can be seen as making it easier on the human pilot conversely you can see it as making it easier to validate the automation by having a human as a backup.

ape4 6y ago

Its cool but would be nice to spend the billions on peaceful activities

iooi 6y ago

Around 19:30 he gets the movement of ailerons wrong, in case anyone else was confused by that. When turning right, the left aileron goes down and the right aileron goes up. https://sites.google.com/site/thebasicsofaviation/rudder-empennage-and-ailerons https://sites.google.com/site/thebasicsofaviation/rudder-emp...

deleted 6y ago
[deleted]