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The big balloon from earlier this month was more like a satellite hanging from a balloon. Not sure it was that cheap. The problem is what can you fly that has

by cm2187 4y ago

The big balloon from earlier this month was more like a satellite hanging from a balloon. Not sure it was that cheap. The problem is what can you fly that has a cannon and can reach those altitudes. Apparently only the F22 and F15 could, and that was their very limit.

deleted 4y ago
[deleted]
oceanplexian 4y ago
That’s definitely not their limit since they can shoot down satellites at the altitude of the International Space Station. And that’s the stuff we’re allowed to know about.
- robswc 4y ago
  Could they shoot down the ISS, if they wanted? Isn't that thing moving insanely fast? haha. Not a space guy but always found it interesting.
  - XorNot 4y ago
    ASAT weapons already exist, so most countries could kill the ISS if they wanted.
  - ianburrell 4y ago
    The SM-3, which is launched from ships for ballistic missile defense, can be used as anti-satellite missile. Its ceiling is supposed to be 1000 km. Which means could reach ISS. It was tested in 2008 to destroy failed recon satellite.
  - vkou 4y ago
    The ISS orbits at ~420 KM. Epotential = mgh = 420,000m * 9.8 m/s^2 * mass ~= 4,200,000 m^2/s^2 * mass To reach that altitude, ignoring air resistance, you'd need kinetic energy, provided by the formula: Ekinetic = (mv^2)/2 Solving for v, we get v = sqrt(8,400,000 m^2/s^2) ~= 2.900 m/s ~= Mach 9 That's the minimum muzzle velocity you need to send a projectile up into the ISS's path (Add a few more mach numbers due to air resistance). It's certainly easier than getting into orbit, a single-stage missile could do it without any trouble.
    - jakeinspace 4y ago
      This calculation is for a ballistic projectile without air resistance. For a missile with a rocket engine, there is no minimum velocity, but you can compute the fuel energy required for the change of altitude. Delta-v isn’t important for a sub-orbital intersection trajectory, although you’ll obviously want your interceptor missile to get there fairly quickly (which will end up being more fuel efficient than a slow climb).
- cm2187 4y ago
  Yeah but not with cannons. We are talking about a cheap way to shoot it down, ie not with a missile.
jcrites 4y ago
The shootdowns did not involve using airplane guns/cannons. Those are less accurate, especially at the engagement range (the aircraft were at 40,000 ft., IIRC, and shooting at 60,000 ft. balloons), and would have likely damaged the payload. The shoot-downs used AIM-9 Sidewinder missiles (per TFA). We also don’t know the ceiling altitude of the F-22 since it’s classified. However, the F-22 can carry the AIM-120 Advanced Medium Range Air to Air Missile (AMRAAM) which has a disclosed engagement altitude of 70,000 feet - capable of engaging even higher altitude balloons than these. As I understand it, the Extended Range AMRAAM-ER is believed to have an engagement ceiling of 85,000 feet. Meanwhile, the US also has the Terminal High Altitude Area Defense (THAAD) anti-ballistic missile system, an air defense system capable of engaging targets at very high altitude. While its capabilities are classified, its max engagement altitude is at least 490,000 ft. or 93 miles … though using it to attack a balloon is like swatting a fly with a sledgehammer. THAAD is mobile and could be deployed in response to a high altitude balloon threat (some of which can fly 120,000 ft.)
- cm2187 4y ago
  Yeah but none of those things are cheap. A cannon is.
  - HeyLaughingBoy 4y ago
    Who says it needs to be cheap? If your budget for X is $Y, there is no benefit to spending less than $Y when you need to do X.
  - jcrites 4y ago
    True, but the max effective range of the F-22’s 20mm M61A2 Vulcan cannon is about 2000 feet (600m), which isn’t nearly enough to engage these balloons — assuming an F-22 is flying at 40,000 ft. vs. a balloon at 60,000 ft. Even if the ceiling of the F-22 is substantially higher than 40,000 ft. (which I think is plausible), and is close enough to effectively engage these balloons, then I doubt that the Air Force would choose to make the tradeoff of disclosing the F-22’s performance capabilities to adversaries in order to save the cost of an AIM-9; the F-22’s performance is a secret and classified. If we were faced with defending against a large number of high-flying objects then the reasoning might be different.
heartbreak 4y ago
Earlier this month? It was last Saturday!

by cm2187 4y ago

deleted 4y ago

[deleted]

oceanplexian 4y ago

That’s definitely not their limit since they can shoot down satellites at the altitude of the International Space Station. And that’s the stuff we’re allowed to know about.

robswc 4y ago
Could they shoot down the ISS, if they wanted? Isn't that thing moving insanely fast? haha. Not a space guy but always found it interesting.
- XorNot 4y ago
  ASAT weapons already exist, so most countries could kill the ISS if they wanted.
- ianburrell 4y ago
  The SM-3, which is launched from ships for ballistic missile defense, can be used as anti-satellite missile. Its ceiling is supposed to be 1000 km. Which means could reach ISS. It was tested in 2008 to destroy failed recon satellite.
- vkou 4y ago
  The ISS orbits at ~420 KM. Epotential = mgh = 420,000m * 9.8 m/s^2 * mass ~= 4,200,000 m^2/s^2 * mass To reach that altitude, ignoring air resistance, you'd need kinetic energy, provided by the formula: Ekinetic = (mv^2)/2 Solving for v, we get v = sqrt(8,400,000 m^2/s^2) ~= 2.900 m/s ~= Mach 9 That's the minimum muzzle velocity you need to send a projectile up into the ISS's path (Add a few more mach numbers due to air resistance). It's certainly easier than getting into orbit, a single-stage missile could do it without any trouble.
  - jakeinspace 4y ago
    This calculation is for a ballistic projectile without air resistance. For a missile with a rocket engine, there is no minimum velocity, but you can compute the fuel energy required for the change of altitude. Delta-v isn’t important for a sub-orbital intersection trajectory, although you’ll obviously want your interceptor missile to get there fairly quickly (which will end up being more fuel efficient than a slow climb).
cm2187 4y ago
Yeah but not with cannons. We are talking about a cheap way to shoot it down, ie not with a missile.

jcrites 4y ago

The shootdowns did not involve using airplane guns/cannons. Those are less accurate, especially at the engagement range (the aircraft were at 40,000 ft., IIRC, and shooting at 60,000 ft. balloons), and would have likely damaged the payload. The shoot-downs used AIM-9 Sidewinder missiles (per TFA). We also don’t know the ceiling altitude of the F-22 since it’s classified. However, the F-22 can carry the AIM-120 Advanced Medium Range Air to Air Missile (AMRAAM) which has a disclosed engagement altitude of 70,000 feet - capable of engaging even higher altitude balloons than these. As I understand it, the Extended Range AMRAAM-ER is believed to have an engagement ceiling of 85,000 feet. Meanwhile, the US also has the Terminal High Altitude Area Defense (THAAD) anti-ballistic missile system, an air defense system capable of engaging targets at very high altitude. While its capabilities are classified, its max engagement altitude is at least 490,000 ft. or 93 miles … though using it to attack a balloon is like swatting a fly with a sledgehammer. THAAD is mobile and could be deployed in response to a high altitude balloon threat (some of which can fly 120,000 ft.)

cm2187 4y ago
Yeah but none of those things are cheap. A cannon is.
- HeyLaughingBoy 4y ago
  Who says it needs to be cheap? If your budget for X is $Y, there is no benefit to spending less than $Y when you need to do X.
- jcrites 4y ago
  True, but the max effective range of the F-22’s 20mm M61A2 Vulcan cannon is about 2000 feet (600m), which isn’t nearly enough to engage these balloons — assuming an F-22 is flying at 40,000 ft. vs. a balloon at 60,000 ft. Even if the ceiling of the F-22 is substantially higher than 40,000 ft. (which I think is plausible), and is close enough to effectively engage these balloons, then I doubt that the Air Force would choose to make the tradeoff of disclosing the F-22’s performance capabilities to adversaries in order to save the cost of an AIM-9; the F-22’s performance is a secret and classified. If we were faced with defending against a large number of high-flying objects then the reasoning might be different.

heartbreak 4y ago

Earlier this month? It was last Saturday!