4 ms·

Actually around 30% of the aircraft weight is for keeping the wetware alive. And a lot of the flight envelope limitations are just to not squish it too hard.

sandworm101 6y ago
Not exactly. There are penty of aerodynamic limitations outside of the pilot. Aircraft might be able to pull a few more gs in some very contrived circumstances, but a pilotless fighter would not be an aerodynamic superman. for instance: Stall/flow separation speeds at paticular wing loadings are often well below the pilot's physical G limitations.
- landryraccoon 6y ago
  How much of that is because engineers designed with those limitations in mind? Nobody has attempted to push what is possible with material science and aerodynamics because there is no point if the pilot wouldn't be able to handle the forces involved. With automation, those limitations no longer apply. For an example of what I'm thinking of, look at air to air missiles. Sidewinder air-to-air missiles achieve an acceleration of 20g, far more than a human pilot can withstand. Drones in the air superiority role could likewise be designed more like larger, more advanced missiles than traditional aircraft. I suspect that if engineers design combat aircraft to be pilotless, you'll soon see them executing maneuvers that would be far too punishing if the craft had to support a human pilot.
  - sandworm101 6y ago
    I mean to say that such limits exist without regard to the pilot, that there is no way around them. Pulling 9+ Gs, trying to sustain that for more than a second or two, isnt really possible in the vast majority of situations. The air is only so thick at a given altitude. The wings can only be so big before structural issues dominate. And remember too that the whole dogfighting concept, the getting behind the other guy for a tail shot, means less and less in a world of all-aspect missiles that can fire in almost any direction.
  - nradov 6y ago
    Nonsense. The compressor will stall.
  - stouset 6y ago
    ITT: people who put way too much faith in how planes fly in movies. High-G maneuvers just are not a wildly important part of aircraft operations. Despite what you see in movies, high-G maneuvers aren’t what defeat radar-guided missiles and they’re not the bread and butter of dogfights either (which are all but a thing of the past). They sure do look good at airshows though. At the end of the day, if you’re a bomb or missile truck, you’re simply not going to outmaneuver a solitary missile that can perform 20G turns. You’re vastly better off minimizing your radar signature and taking out enemy radar sources using SEAD, at which point you can fly with impunity.
  - chipsa 6y ago
    No, it's because the engineers have to balance structure weight versus everything else. F-15As are G limited to 7.3G. The Cs are limited to that same amount at altitude. F-18s were limited to 7.5G as well. And both of those are with "clean" aircraft. Start putting munitions and external fuel on, and that limit starts going down, because they wings have more weight to withstand.
nickff 6y ago
That 30% is very much on the high side, and would only be true on something like a single-engine fighter. Initial flight envelope requirements are often drafted to be the maximum a pilot can take, but there are other considerations. Designing an airframe that can handle a 20G turn will actually make it less maneuverable overall, as it requires a heavier structure. Fighter design is a delicate balancing act.
- xoa 6y ago
  >That 30% is very much on the high side, and would only be true on something like a single-engine fighter. ...like the F-35? I mean, I don't have any idea at all what the exact percentage is, but that is the apropos isn't it? >but there are other considerations. Designing an airframe that can handle a 20G turn will actually make it less maneuverable overall, as it requires a heavier structure. Sure, but 30% heavier? Because if not seems like it would indeed be a win. I don't disagree at all that fighter design is a balancing act, that comes up in quite a few industries that push the edge particularly in aerospace. But fundamentally at least from other industries I am more familiar with there can often be disruptive gains when some single factor changes in a major way since changes so often are compounding. We seem to be on the verge of a big example of that in space with SpaceX and Starship. Far more mass and cadence for radically less money changes design considerations up and down the stack. When every single gram is expensive, it makes sense to use the most expensive materials and components, and as the overall price goes up it makes sense to try to pack in more and more functionality etc etc. When that changes all those effects go into reverse. We're seeing that directly in fact with Starship development itself. They've got more margin to work with, so they could switch to steel, which is far cheaper and easier to work with, which helps with rapid cadence, which helps with mass manufacturing which further brings down costs, which all helps develop faster and better without bad decisions baked in, which further will help with cadence and ultimate cost, and on and on. The resulting contrast with the SLS program is just staggering. Costs and gains compound on either side for literal orders of magnitude divergence. I don't know if drones will do the same thing for air superiority, but the potential shouldn't be ignored. And probably won't be indefinitely, because the specter of actual competitive level hostile forces seems likely to focus minds despite lobbying by incumbents. Real world results that grow big enough ultimately can't be papered over.

sandworm101 6y ago

Not exactly. There are penty of aerodynamic limitations outside of the pilot. Aircraft might be able to pull a few more gs in some very contrived circumstances, but a pilotless fighter would not be an aerodynamic superman. for instance: Stall/flow separation speeds at paticular wing loadings are often well below the pilot's physical G limitations.

landryraccoon 6y ago
How much of that is because engineers designed with those limitations in mind? Nobody has attempted to push what is possible with material science and aerodynamics because there is no point if the pilot wouldn't be able to handle the forces involved. With automation, those limitations no longer apply. For an example of what I'm thinking of, look at air to air missiles. Sidewinder air-to-air missiles achieve an acceleration of 20g, far more than a human pilot can withstand. Drones in the air superiority role could likewise be designed more like larger, more advanced missiles than traditional aircraft. I suspect that if engineers design combat aircraft to be pilotless, you'll soon see them executing maneuvers that would be far too punishing if the craft had to support a human pilot.
- sandworm101 6y ago
  I mean to say that such limits exist without regard to the pilot, that there is no way around them. Pulling 9+ Gs, trying to sustain that for more than a second or two, isnt really possible in the vast majority of situations. The air is only so thick at a given altitude. The wings can only be so big before structural issues dominate. And remember too that the whole dogfighting concept, the getting behind the other guy for a tail shot, means less and less in a world of all-aspect missiles that can fire in almost any direction.
- nradov 6y ago
  Nonsense. The compressor will stall.
- stouset 6y ago
  ITT: people who put way too much faith in how planes fly in movies. High-G maneuvers just are not a wildly important part of aircraft operations. Despite what you see in movies, high-G maneuvers aren’t what defeat radar-guided missiles and they’re not the bread and butter of dogfights either (which are all but a thing of the past). They sure do look good at airshows though. At the end of the day, if you’re a bomb or missile truck, you’re simply not going to outmaneuver a solitary missile that can perform 20G turns. You’re vastly better off minimizing your radar signature and taking out enemy radar sources using SEAD, at which point you can fly with impunity.
- chipsa 6y ago
  No, it's because the engineers have to balance structure weight versus everything else. F-15As are G limited to 7.3G. The Cs are limited to that same amount at altitude. F-18s were limited to 7.5G as well. And both of those are with "clean" aircraft. Start putting munitions and external fuel on, and that limit starts going down, because they wings have more weight to withstand.

nickff 6y ago

That 30% is very much on the high side, and would only be true on something like a single-engine fighter. Initial flight envelope requirements are often drafted to be the maximum a pilot can take, but there are other considerations. Designing an airframe that can handle a 20G turn will actually make it less maneuverable overall, as it requires a heavier structure. Fighter design is a delicate balancing act.

xoa 6y ago
>That 30% is very much on the high side, and would only be true on something like a single-engine fighter. ...like the F-35? I mean, I don't have any idea at all what the exact percentage is, but that is the apropos isn't it? >but there are other considerations. Designing an airframe that can handle a 20G turn will actually make it less maneuverable overall, as it requires a heavier structure. Sure, but 30% heavier? Because if not seems like it would indeed be a win. I don't disagree at all that fighter design is a balancing act, that comes up in quite a few industries that push the edge particularly in aerospace. But fundamentally at least from other industries I am more familiar with there can often be disruptive gains when some single factor changes in a major way since changes so often are compounding. We seem to be on the verge of a big example of that in space with SpaceX and Starship. Far more mass and cadence for radically less money changes design considerations up and down the stack. When every single gram is expensive, it makes sense to use the most expensive materials and components, and as the overall price goes up it makes sense to try to pack in more and more functionality etc etc. When that changes all those effects go into reverse. We're seeing that directly in fact with Starship development itself. They've got more margin to work with, so they could switch to steel, which is far cheaper and easier to work with, which helps with rapid cadence, which helps with mass manufacturing which further brings down costs, which all helps develop faster and better without bad decisions baked in, which further will help with cadence and ultimate cost, and on and on. The resulting contrast with the SLS program is just staggering. Costs and gains compound on either side for literal orders of magnitude divergence. I don't know if drones will do the same thing for air superiority, but the potential shouldn't be ignored. And probably won't be indefinitely, because the specter of actual competitive level hostile forces seems likely to focus minds despite lobbying by incumbents. Real world results that grow big enough ultimately can't be papered over.