The article is very vague on how the radioactivity allows detection of leaking gas.
The video at the bottom explains from 7:50 in. Gas pressure pressing on a spring holds a radiation shield in place. If the gas leaks the shield moves and the radiation can be detected.
show comments
simonbw
I can just imagine the conversation when they came up with that:
Boss: we need to transmit 1 bit of information indicating pressure loss from a spinning rotor blade to the main body of the helicopter. The blade spins too fast for electronics to work properly.
Engineer: What if we make the blades radioactive when they depressurize, then point a Geiger counter at them to detect if that happens.
Boss: ... where did you say you got your degree from?
gorgoiler
I don’t have a good intuition for the aerodynamic environment around a helicopter blade in flight. It feels like it ought to be very blustery. Presumably there’s a huge amount of pressure on the underside and a drop in pressure on the top side, maybe even below atmospheric pressure?
The blades are a foot wide and 30’ long, so five of them carrying 25,000lbs is about 1psi of pressure. 3x that for a laden Stallion. I guess I expected it to be a lot more because, from the perspective of the rotor blade, it is in a very windy regime.
The other major open question for me is with the cracks. The system implies there is a non instantaneous progression from unbroken, to having a small crack on the surface, to having a crack large enough for nitrogen to escape, to having a crack so large that the rotor blade fails. I’d love to know what sort of timeframes sit between each of these phases.
patwolf
Often in software development I encounter code that seems overly complex. It's not always obvious at first glance whether that complexity is because it's solving a really difficult problem, or because the developers made it more complex than it needed to be.
Having no domain knowledge of the problems of detecting cracks in blades, this sounds like either a genius solution to a super hard problem, or unnecessary complexity.
show comments
linksnapzz
Heh...I actually knew about this.
A friend's cousin was a CH-53 pilot out of MCAS Miramar. One day, he was telling us, someone didn't properly secure one of the (chairs? racks? don't know the rotorcraft term...)in the cargo hold. The doors were open, and they were flying above the desert at a few thousand feet when...one of the aluminum & webbing chairs got sucked out the window and hit a rotor.
The number & intensity of the warning lights in the cockpit, and the accompanying alarms when that happens is pretty spectacular. The pilot knows right away.
What if the helicopter would have to operate in a contaminated area? Wouldn't it cause false positives?
> The CH-53 Sea Stallion first entered service in 1966
1966 is Cold War era, so, I think, an idea that a military helicopter would have to fly in an area that has been recently nuked wasn't totally inconceivable...
> The solution is so elegant it’s still being used today. The newest versions of the CH-53 of fiber optics to detect faults in the newest all-composite blades. The older variants? They’re still going with the nuclear option.
Huh? So it's not really in use today as much as hasn't been retrofit out. Those are very different. This also doesn't read well. Maybe rewritten without proofreading
show comments
ErroneousBosh
Some really hyperbolic comments on there:
JohnU says: "It’s all fun and games until helicopter crashes and what should be a minor incident turns into a nuclear emergency where you have to call very specialized decontamination units to remove radioactive material from the site."
Alan Reid says: "unless they shoot ’em down on your own territory
then you don’t have a helicopter but you have mini-hiroshima to clean up."
How much Strontium-90 do they think these things are carrying?
Do they have smoke detectors at home (I hope so...)?
The article is very vague on how the radioactivity allows detection of leaking gas.
The video at the bottom explains from 7:50 in. Gas pressure pressing on a spring holds a radiation shield in place. If the gas leaks the shield moves and the radiation can be detected.
I can just imagine the conversation when they came up with that:
Boss: we need to transmit 1 bit of information indicating pressure loss from a spinning rotor blade to the main body of the helicopter. The blade spins too fast for electronics to work properly.
Engineer: What if we make the blades radioactive when they depressurize, then point a Geiger counter at them to detect if that happens.
Boss: ... where did you say you got your degree from?
I don’t have a good intuition for the aerodynamic environment around a helicopter blade in flight. It feels like it ought to be very blustery. Presumably there’s a huge amount of pressure on the underside and a drop in pressure on the top side, maybe even below atmospheric pressure?
The blades are a foot wide and 30’ long, so five of them carrying 25,000lbs is about 1psi of pressure. 3x that for a laden Stallion. I guess I expected it to be a lot more because, from the perspective of the rotor blade, it is in a very windy regime.
The other major open question for me is with the cracks. The system implies there is a non instantaneous progression from unbroken, to having a small crack on the surface, to having a crack large enough for nitrogen to escape, to having a crack so large that the rotor blade fails. I’d love to know what sort of timeframes sit between each of these phases.
Often in software development I encounter code that seems overly complex. It's not always obvious at first glance whether that complexity is because it's solving a really difficult problem, or because the developers made it more complex than it needed to be.
Having no domain knowledge of the problems of detecting cracks in blades, this sounds like either a genius solution to a super hard problem, or unnecessary complexity.
Heh...I actually knew about this.
A friend's cousin was a CH-53 pilot out of MCAS Miramar. One day, he was telling us, someone didn't properly secure one of the (chairs? racks? don't know the rotorcraft term...)in the cargo hold. The doors were open, and they were flying above the desert at a few thousand feet when...one of the aluminum & webbing chairs got sucked out the window and hit a rotor.
The number & intensity of the warning lights in the cockpit, and the accompanying alarms when that happens is pretty spectacular. The pilot knows right away.
When I read the title I thought it would be about depleted uranium, which other aircraft have used as weight: https://en.wikipedia.org/wiki/Depleted_uranium#Trim_weights_...
What if the helicopter would have to operate in a contaminated area? Wouldn't it cause false positives?
> The CH-53 Sea Stallion first entered service in 1966
1966 is Cold War era, so, I think, an idea that a military helicopter would have to fly in an area that has been recently nuked wasn't totally inconceivable...
See too the Porsche 917[0].
[0] https://en.wikipedia.org/wiki/Porsche_917?#Construction
> The solution is so elegant it’s still being used today. The newest versions of the CH-53 of fiber optics to detect faults in the newest all-composite blades. The older variants? They’re still going with the nuclear option.
Huh? So it's not really in use today as much as hasn't been retrofit out. Those are very different. This also doesn't read well. Maybe rewritten without proofreading
Some really hyperbolic comments on there:
JohnU says: "It’s all fun and games until helicopter crashes and what should be a minor incident turns into a nuclear emergency where you have to call very specialized decontamination units to remove radioactive material from the site."
Alan Reid says: "unless they shoot ’em down on your own territory
then you don’t have a helicopter but you have mini-hiroshima to clean up."
How much Strontium-90 do they think these things are carrying?
Do they have smoke detectors at home (I hope so...)?
Terrible explanation