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The Helicopter with Radioactive Blades
- calmbonsai 7d agoWait until the general public learns about the tech behind most of the currently fielded smoke detectors. Also, this has long-since been obviated with active acoustic/vibration detection in modern rotor drive-trains. All that said, every registered civilian and military chopper has high duty-cycle manual inspection of rotor blades too. They use both their Mark I eye-balls and ultrasonic transducers.
- p0w3n3d 7d agoSafe for humans as long as they do not breathe it. We're flying. In the air, and there is a rotating strontium spreader above us. How we're not going to breathe it in?
- 46Bit 9d agoThe 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.
- tomasphan 9d agoThe titanium spar is filled with gas. If there was a crack in the spar the gas would escape, therefore tripping the pressure sensitive radiation shield. Releasing radiation that can be detected inside the helicopter. Wireless systems aren’t used for opsec reasons.
- sandworm101 8d agoWireless arent used because they need power/wires and are less reliable than IBIS. Civilian versions of sikorsky helos use the same system.
- DoctorOetker 8d agocarrying a radiation source doesn't sound very opsec either to be honest...
- pixl97 8d agoWhy? It's not like it's gamma radiation.
- Johnny555 8d agoSince the radiation source is only exposed if it's indicating a potential main rotor crack, and it's not a very strong radiation source in the first place (so it's not like it allows long distance tracking), it seems like a minor risk -- if the radioactive capsule is exposed, the pilot is going to be returning to safe place to land. Beta particles typically only travel a few meters in air before they lose most of their energy.
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- kstrauser 8d agoWait until you find out about smoke detectors. Or microwave ovens. Or light bulbs. Or anything with nonzero temperature.
- robocat 9d agoThere's a good comment: MH-53E maintainer here. The system is IBIS (Inflight Blade Inspection System) and the little pods are BIM (blade inspection monitors). The box is pretty obvious sitting just behind the main rotor on the deck above the center engine. I found a random picture on the web: https://assets.verticalmag.com/wp-content/uploads/2017/01/MHM_6001.jpg https://assets.verticalmag.com/wp-content/uploads/2017/01/MH... And: The IBIS devices provide in-flight warning of blade failure on various models of helicopters. One device is located on the root of each blade attached to the rotor. The IBIS detects a decrease in pressure in the blades of a CH-53 model helicopter. Any cracks in the blades will result in a decrease in air pressure in the blade. Such cracks could result in structural failure in the blade, thereby resulting in a potentially dangerous operational situation for the helicopter, such as a hard landing and/or injury to the craft and/or personnel up to, and including, death. Each device contains approximately 500 microcuries (18.5 MBq) of strontium-90 (Sr-90) in the form of a rolled metal foil, encased in a small stainless steel protective cylinder about the size of the press button on a ballpoint pen. The external radiation level of the IBIS is 0.8 mR/hr at 3 inches in the normal (shielded) mode, and 75 mR/hr at 12 inches in the failure (extended) mode. From https://public-inspection.federalregister.gov/2019-08531.pdf?1556282725 https://public-inspection.federalregister.gov/2019-08531.pdf...
- laxpri 8d agoWhat does “inches” mean here
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- pachouli-please 8d agoPresumably the measure of distance from the source to receive dosages under those conditions.
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- hansvm 8d ago
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- lstodd 8d agoRadioactivity has nothing to do with it. Was solved in Mi-6/Mi-8/Mi-26 blades without it.
- vova_hn2 9d agoWhat 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...
- stackghost 9d agoExposure to a nuclear blast doesn't necessarily make things radioactive. Hiroshima and Nagasaki are not radioactive wastelands. Even in Chernobyl, the other reactors continued to operate for a time after the accident, and nature is thriving. But, the radiation detector is on the upper surface of the rear fuselage. Hypothetical Beta particles from the ground will strike the underside of the aircraft and not the detector.
- xattt 9d ago> Exposure to a nuclear blast doesn't necessarily make things radioactive Isn’t this neutron activation?
- stackghost 9d agoIt is, but a) it's a probabilistic process and b) most of the products decay rapidly, down to the background level in a matter of days.
- pixl97 8d agoGenerally they are going to airburst to cause maximum damage over an area which means what free neutrons hit are gasses which dispurse pretty quickly. Ground detonation does cause more fallout though.
- lazide 8d agoStrontium-90 is a major component of fallout and strongly in the ‘really not good for you’ category.
- patwolf 9d agoOften 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.
- lordnacho 9d agoChesterton's Fence
- throwway120385 9d agoGiven the forces involved, the need to avoid wireless communication, the complexity of any bearing with associated electrical contact, and so on this seems like the least complicated solution. You can rely on radioactive elements to emit radioactivity above background, you can build a pretty reliable pressure indicator, and you can fill a cavity in the blades with gas pretty reliably. You sidestep all of the complicated mechanical linkages in favor of a solution that's not in the rotor hub at all.
- SoftTalker 9d agoI though it sounded pretty clever. Now, that can be good or bad depending on context. I mean it in a good way. It seems simple conceptually (I have no idea if it adds a lot of complexity to the manufacturing) and rather foolproof. I guess the radiation shield could jam and not move when it should.
- fluorinerocket 9d agoTerrible explanation
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- bigbuppo 8d agoHackaday isn't the end-all, be-all authoritative source for anything. It's a blog that, for the most part, links to neat stuff with a summary write-up. If something interests you then it's on you to follow the links. This is how the web used to work.
- bookofjoe 8d agoI miss those days.
- bigbuppo 7d agoSorry, all out of the good old days. All we have are people working in tech too ashamed to admit they're a willing and complicit part of the surveillance state under the auspices of working in something they also won't admit is marketing or advertising tech, but is 100% just that.
- ErroneousBosh 8d agoSome 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...)?
- alnwlsn 8d agoYou must not hang out on there. Those are some pretty standard grade Hackaday comments. I love the site, read every day, but the comments section can be... rough.
- saltcured 8d agoOn the bright side, now we can have another comparison scale, for how many banana-copters worth of radiation a given item contains.
- ErroneousBosh 8d agoOccasionally I browse the comments when something I've worked on is misunderstood on there. You should never read the comments.
- bch 8d agoSee too the Porsche 917[0]. [0] https://en.wikipedia.org/wiki/Porsche_917?#Construction https://en.wikipedia.org/wiki/Porsche_917?#Construction
- Neywiny 8d ago> 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
- Johnny555 8d agoIf it hasn't been retrofitted out, then it's still in use today. That sentence would only be incorrect if the new solution was retrofitted on all aircraft.
- simonbw 8d ago> is so elegant it’s still being used today I think it's the "so elegant" part that's wrong. It's not still being used today because it's so elegant. It's still being used today because the old helicopters haven't replaced it.
- 3eb7988a1663 8d agoI think elegance has to do with the technology of the time. Some clever design that is cheaper/better than you would otherwise think possible given the era. There are probably many elegant aspects to Roman aqueduct engineering, but they would still get replaced with modern materials during a retrofit.
- datadrivenangel 8d agoif it was less elegant from a function/cost perspective, it would have been replaced a long time ago.
- linksnapzz 8d agoHeh...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.
- simonbw 8d agoI 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 8d agoI 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.
- userbinator 8d agoWhen 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_in_aircraft https://en.wikipedia.org/wiki/Depleted_uranium#Trim_weights_...
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- m4rtink 8d agoThis definitely come from the same category as F-16 potentially releasing hydrazine when it crashes, as it is used to power its auxiliary power unit in an emergency: https://en.wikipedia.org/wiki/Hydrazine#Gas_producers_and_propellants https://en.wikipedia.org/wiki/Hydrazine#Gas_producers_and_pr... https://pmc.ncbi.nlm.nih.gov/articles/PMC12542269/ https://pmc.ncbi.nlm.nih.gov/articles/PMC12542269/ https://aviation.stackexchange.com/questions/23417/why-is-hydrazine-used-to-power-the-f-16s-epu https://aviation.stackexchange.com/questions/23417/why-is-hy... First you usually go "WTF, why would they do that ?" but on a second look it usually makes perfect sense & is quite an elegant, if unorthodox engineering solution.