I agree with your comments. I was startled to see how few were going to be produced. This puts me in mind of the fleet size resulting from Obama's termination of F-22 production. I get the impression that this airplane is expected to operate at altitudes and airspeeds where dogfights are not feasible, relying on its pack of fighter dogs to carry the battle. So, I very much agree it should be a 2-seater. I can't understand why they thought this would be feasible as a one-man operation. (It's amazing. We are warned constantly about distractions while driving, but it appears to be no problem to manage a swarm of drones while piloting.)
I will be very curious to see if and how they integrate a laser weapon into the airplane. The power level would probably be in the range of 100-300 kW optical power at 1 micron wavelength. Electrical lasers have about a 30% quantum efficiency, so that would mean the need to dissipate ~200-600 kW of thermal loading. That might be the limiting consideration on the beam power, as the fuel is the only available heat sink. The problem that is not considered is that this power has to come from somewhere, most likely from the engine turbine shaft as a power take-off. There will be an inevitable RPM slowdown as something like 400-1000 kW of mechanical power is pulled off the turbine, and a corresponding loss of thrust. I tried to make this point to my section manager who was a retired Air Force colonel, but he was oblivious to the requirements of the First Law of thermodynamics. He thought that there was always going to be a surplus of engine power at constant throttle.
The pointer-tracker head will need to be retractable in order to preserve stealth when not operating. Laser operation will probably require subsonic flight conditions, as the optics are greatly affected by the freestream flow and the boundary layers around the aperture, possibly contributing to beam jitter. Contrary to cartoons and movies, the beam is not equally effective in all directions. The worst direction is straight ahead, which is the most prone to beam blooming because transiently heated air stays within the beam column. The best direction is to the side ("abeam" in nautical terms), where the air is moving across the beam and not lingering in it. In an upcoming laser engagement, the pilot might need to assume a diagonal track in order to place the target away from his nose and more toward his wing. Laser dwell times will be seconds. No such thing as an instantaneous hit. The beam travels at the speed of light, but the target effects depend on heat accumulation. The softest target is the enemy cockpit. At open-fire intensities of 100 W/cm2, the beam will go through a polymer canopy as though it were cellophane and bounce around inside the cockpit like a microwave oven. The pilot would be fried to a crisp before he would be aware of it. This kind of engagement would be possible at distances greater than which the F-47 could be seen. Very spooky threat, death out of nowhere.
This introduces the question of whether the F-47 pilot would need cockpit protection from an enemy laser. In our weapon system studies of the late 70s and early 80s, we never got to the point of evaluating an air-to-air laser duel. In such a case, if you can lock onto the enemy laser beam director and shoot into it, that might ruin his beam optics. This leads to the notion of two beam directors, to have a spare if the first one is put out of action by such a tactic. This may be the point at which the airplane adopts an opaque reflective metallic canopy and supports the pilot with video feed from multiple cameras (with nuclear-flash shutters to prevent blinding by a threat laser).
It would be an ideal weapon against sitting duck targets, like transports, tankers, and bombers.
Apparently, there are cadets at Colorado Springs who take the engineering track, and those who take the history track. He was a pretty smart guy and was on an important technical advisory committee, but he seemed to think a weapon laser had a power draw comparable to a radar set: no big deal. The more one looks into it, integrating a laser weapon could involve some significant internal changes in component location and space, thermal management, power management, and airframe isolation from the pointer-tracker. I really have my doubts that so much modification would be tolerated for something as tightly designed as the F-47.
Yes. And I remember every area was stealing a little bit of the F-22’s weapons bay in the design. They had a big crack down and it took practically an act of God to get another cubic inch out of the weapons bay. It was the incentive for me to come up with the Small Powerful Bomb. My energetics efforts faded though and we got the Small Diameter Bomb. Which turned out to be a hit. I really like the ground launched version too.
I agree with your comments. I was startled to see how few were going to be produced. This puts me in mind of the fleet size resulting from Obama's termination of F-22 production. I get the impression that this airplane is expected to operate at altitudes and airspeeds where dogfights are not feasible, relying on its pack of fighter dogs to carry the battle. So, I very much agree it should be a 2-seater. I can't understand why they thought this would be feasible as a one-man operation. (It's amazing. We are warned constantly about distractions while driving, but it appears to be no problem to manage a swarm of drones while piloting.)
I will be very curious to see if and how they integrate a laser weapon into the airplane. The power level would probably be in the range of 100-300 kW optical power at 1 micron wavelength. Electrical lasers have about a 30% quantum efficiency, so that would mean the need to dissipate ~200-600 kW of thermal loading. That might be the limiting consideration on the beam power, as the fuel is the only available heat sink. The problem that is not considered is that this power has to come from somewhere, most likely from the engine turbine shaft as a power take-off. There will be an inevitable RPM slowdown as something like 400-1000 kW of mechanical power is pulled off the turbine, and a corresponding loss of thrust. I tried to make this point to my section manager who was a retired Air Force colonel, but he was oblivious to the requirements of the First Law of thermodynamics. He thought that there was always going to be a surplus of engine power at constant throttle.
The pointer-tracker head will need to be retractable in order to preserve stealth when not operating. Laser operation will probably require subsonic flight conditions, as the optics are greatly affected by the freestream flow and the boundary layers around the aperture, possibly contributing to beam jitter. Contrary to cartoons and movies, the beam is not equally effective in all directions. The worst direction is straight ahead, which is the most prone to beam blooming because transiently heated air stays within the beam column. The best direction is to the side ("abeam" in nautical terms), where the air is moving across the beam and not lingering in it. In an upcoming laser engagement, the pilot might need to assume a diagonal track in order to place the target away from his nose and more toward his wing. Laser dwell times will be seconds. No such thing as an instantaneous hit. The beam travels at the speed of light, but the target effects depend on heat accumulation. The softest target is the enemy cockpit. At open-fire intensities of 100 W/cm2, the beam will go through a polymer canopy as though it were cellophane and bounce around inside the cockpit like a microwave oven. The pilot would be fried to a crisp before he would be aware of it. This kind of engagement would be possible at distances greater than which the F-47 could be seen. Very spooky threat, death out of nowhere.
This introduces the question of whether the F-47 pilot would need cockpit protection from an enemy laser. In our weapon system studies of the late 70s and early 80s, we never got to the point of evaluating an air-to-air laser duel. In such a case, if you can lock onto the enemy laser beam director and shoot into it, that might ruin his beam optics. This leads to the notion of two beam directors, to have a spare if the first one is put out of action by such a tactic. This may be the point at which the airplane adopts an opaque reflective metallic canopy and supports the pilot with video feed from multiple cameras (with nuclear-flash shutters to prevent blinding by a threat laser).
It would be an ideal weapon against sitting duck targets, like transports, tankers, and bombers.
Excellent evaluation!! I guess your colonel slep through Thermo class.
Apparently, there are cadets at Colorado Springs who take the engineering track, and those who take the history track. He was a pretty smart guy and was on an important technical advisory committee, but he seemed to think a weapon laser had a power draw comparable to a radar set: no big deal. The more one looks into it, integrating a laser weapon could involve some significant internal changes in component location and space, thermal management, power management, and airframe isolation from the pointer-tracker. I really have my doubts that so much modification would be tolerated for something as tightly designed as the F-47.
Yes. And I remember every area was stealing a little bit of the F-22’s weapons bay in the design. They had a big crack down and it took practically an act of God to get another cubic inch out of the weapons bay. It was the incentive for me to come up with the Small Powerful Bomb. My energetics efforts faded though and we got the Small Diameter Bomb. Which turned out to be a hit. I really like the ground launched version too.
Good for you! I like energetics, though my interest was in more powerful rocket fuels.