9 ms·
Rocket Helicopter (2010)
- maxbaines 6y agoSeems obvious now I see it!
- jeffreyrogers 6y agoThe way these work is pretty interesting. Rather than combusting a fuel and an oxidizer as in a typical rocket, these use hydrogen peroxide that is exposed to a platinum catalyst, which causes the rapid decomposition of h202 into h20 and 02, which is then expelled through the rocket nozzle, generating thrust. This greatly simplifies the design of the rocket engine.
- arethuza 6y agoH202 rockets have been around for a long time. Indeed, the UK's only self launched satellite was on a launcher using the stuff: https://en.wikipedia.org/wiki/High-test_peroxide https://en.wikipedia.org/wiki/High-test_peroxide
- liability 6y agoThe German V2 rockets also used hydrogen peroxide and a catalyst (sodium or possibly potassium permanganate) to drive their turbopumps (which pumped LOx and alcohol into the engine.) Here's a pretty good 2.5 hour long documentary about the V2 turbopumps specifically: https://youtube.com/watch?v=EgiMu8A3pi0 https://youtube.com/watch?v=EgiMu8A3pi0 (The H2O2/catalyst system is discussed/demonstrated around the 45 minute mark.)
- avmich 6y agoRussian Soyuz rocket family still uses hydrogen peroxide for driving pumps on engines of 1st and 2nd stages - RD-107 and RD-108. The only - notable - exception is Soyuz 2-1v, which has no boosters and the 1st stage engine is famous NK-33. That's a whole different story.
- mannykannot 6y agoThe claim in this article is that the motors use 70% hydrogen peroxide with alcohol (it does not say which one), without a catalyst. I have not found any explanation of the alcohol's purpose, or whether it is oxidzed in the process.
- thescriptkiddie 6y agoIt could be a "mixed monopropellant". The H2O2 decomposes to H2O + O2, presumably at high enough temperature to react the O2 with the alcohol (probably ethanol or methanol). As an added benefit your exhaust gas is no longer oxygen-rich, which can cause problems.
- skykooler 6y agoIt's confusing, because at the top they say "This rockets don't use a catalyst" but further down the page they say "all this thanks to our proprietary formula of the penta metallic catalyst pack invented by Juan Manuel Lozano Gallegos from TAM." (Side note: I saw that name and wondered where I had seen it before; turns out he's the guy Popular Science wrote about fifteen years ago for building his own peroxide-powered jetpack.)
- Gravityloss 6y agoMaybe they meant the catalyst is not a liquid catalyst that is consumed.
- mrtnmcc 6y agoDoes this mean there is only one fuel line feeding up to the prop, not two that would get twisted by rotation?
- jeffreyrogers 6y agoMy guess is they have a fuel line running to the rotor head, and then some sort of seal which allows for rotation and for feeding the fuel into the rotors.
- pueblito 6y agoWhy doesn't this helicopter need a tail rotor? I was under the impression that it was to counteract the spinning main rotor
- liability 6y agoIn a normal helicopter, the helicopter is exerting a force on the rotors and thus feels an equal and opposite force that needs to be countered, either by a tail rotor or a counter-rotating rotor. This helicopter doesn't do that. If anything I'd think it might need a tail rotor to stop it from spinning in the same direction as the rotor, but I guess friction between the helicopter body and the rotor is low enough that this isn't a serious concern. (The linked youtube video shows a version of this helicopter that does have such a tail rotor, though positioned closer to the helicopter than it might normally be.)
- bzax 6y agoThe equal and opposite torque is provided by the blade tip rockets instead by the helicopter body.
- LeifCarrotson 6y agoIt is, the tail rotor is needed because on a conventional helicopter the main rotor is spun using a torque force from the helicopter body, through the engine/gearbox, and into the rotor. On this helicopter, the force is from the rotor through the rockets to the air, there's only a tiny friction force dragging the body along with the main rotor, and it looks like that's small enough to be counteracted by the aerodynamics.
- deleted 6y ago[deleted]
- vannucci 6y agoWhen the engine on top of a helicopter spins the blades, they exert an equal torque force back on the body of the helicopter. In order to just spin the blades and keep the body straight, you have to cancel that torque by using a tail rotor which creates a force way back on the tail that with the length of the tail, cancels it out. In the case of this helicopter, the force to spin the blades comes from the tips of the blades, expelling gas out the tips will push the blade tips forward, so the body doesn't push on the rotor blades at all to spin them.
- arethuza 6y agoSomething that spins around at high speed using 70% hydrogen peroxide.... Don't think I'd want to be anywhere close to that device.
- Someone 6y agoIt doesn’t spin that fast (linear speed) close to the helicopter, and any fuel leaking out of the wings during flight will fly outwards so you would be safe inside ;-) However, I expect they pump the fuel from the helicopter body into the wings, and I wonder how they guarantee the seal between the two. Helicopters must continuously adjust the angle of attack of the wings, so it isn’t even a matter of a single fixed axis, and the chemical properties of hydrogen peroxide won’t make things easier.
- jeffreyrogers 6y ago> I expect they pump the fuel from the helicopter body into the wings, and I wonder how they guarantee the seal between the two. I was wondering about that too. I haven't found a good explanation anywhere.
- regularfry 6y agoOnce it's started up, it's a centrifugal pump all on its own. You don't need a positive pressure pump on the body, the fuel would be sucked out and along the blades like a siphon. That doesn't make the seal problem much easier, but it at least does mean that if a seal were to fail, it would fail safe without spewing h2o2 everywhere.
- baldeagle 6y agoI'm a little skeptical about the claim of 'performance is the same at any altitude'... while yes, the engine performance is similar at altitude, the helo performance is not (what with the fewer air bits for the blades to move around)
- liability 6y agoYes, it's my impression that helicopters have problems with thin air reducing lift long before they lose engine power. That's why it's easier for them to fly forward than hover at high altitudes; the forward velocity of a moving helicopter provides more airflow over the rotors and thus more lift. I don't think it's a matter of jamming more air into the turboshaft engines, which presumably could be done using larger intakes.
- MaxBarraclough 6y ago> it's my impression that helicopters have problems with thin air reducing lift long before they lose engine power. I believe this is generally true, but it's certainly possible to get into trouble. The world record for the longest autorotation was set after an engine flameout, after an attempt at the world record for highest altitude reached in a helicopter. [0] > the forward velocity of a moving helicopter provides more airflow over the rotors and thus more lift It's more that a helicopter in a hover (assuming little wind) must produce additional lift (i.e. more power) as it's stuck in a downdraught of its own creation. Introduce some forward movement, and the helicopter is flying through undisturbed air (or more precisely, the air entering the main rotor disc is undisturbed), which takes far less power. This is called 'translational lift'. It kicks in at around 30 knots, and occurs at any altitude. It might be more consequential at very high altitude though, or under very heavy load, where the helicopter might have enough power for forward flight, but inadequate power for a hover. [1] The FAA have an interesting Power vs airspeed chart, p19 of [2]. If I understand correctly, it means that if your goal is to keep a helicopter in the air as long as possible, you want to stay at around 62 knots of indicated airspeed. Fairly slow, but nowhere near a hover. (edit 'Ground effect' might also have some bearing on that question, but that's another matter.) [0] https://en.wikipedia.org/wiki/Jean_Boulet https://en.wikipedia.org/wiki/Jean_Boulet [1] https://en.wikipedia.org/wiki/Translational_lift https://en.wikipedia.org/wiki/Translational_lift [2] (PDF warning) https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/helicopter_flying_handbook/media/hfh_ch02.pdf https://www.faa.gov/regulations_policies/handbooks_manuals/a...
- AgloeDreams 6y agoHonestly makes a lot of sense. Might be possible do do it as a ram jet too, that would get you a lot of efficiency upsides. Typical jet engines probably wouldn't work well however due to force but you get a fuel feed upside from the centrifugal force.
- mnw21cam 6y agoRamjets work at supersonic airflow speeds. You really don't want your helicopter blade tips going supersonic.
- deleted 6y ago[deleted]
- AgloeDreams 6y agoWouldn't it be possible to use a subsonic inlet but design the intake to allow for air to become super sonic in the flow?
- checker 6y agoFair warning, this is probably a ridiculous idea because I'm nothing close to a mechanical/aerospace engineer. Would it be possible to mount the ramjets to a ring around the blades along with some sort of transmission in the ring? I'm thinking setup this would allow the ramjets to function supersonically at the edge of the structure to ensure the best airflow and limit the speed of the blades. However such a transmission might be overly complex or heavy and it's possible that the ring around the blades would cause some weird aerodynamic effects. Thanks for obliging my curiosity!
- chipsa 6y agoRamjets do not require supersonic flow speeds. They require positive speed (they don't work at a standstill), and are usually tuned for a sweet spot. This is usually supersonic because most applications are military, where the supersonic capability is desired. That said,they usually don't produce much thrust until you get over M0.5.
- jeffreyrogers 6y ago
- gostsamo 6y agoIsn't this fuel rather toxic in case of accident?
- arethuza 6y agoOne of concerns would be how much of it gets converted by the catalyst - if it's not 100% for any reason you've basically got a rotating sprinkler throwing HTP about. Edit: To be fair it's not HTP, fortunately for those under the flight path...
- rbanffy 6y agoEveryone around it will turn blonde.
- GekkePrutser 6y agoThe Nazis would have loved this thing :D
- Justsignedup 6y agoCan this be converted to use standard combustible fuel? I wonder if this can be converted to a jet engine that pumps pressurized air out of the ends of the blade rather than this stuff.
- liability 6y agoMaybe that could be made to work, but if you're already committed to using a gas turbine of any sort, why not make it a turboshaft engine and build a conventional helicopter? Either way you have to pay for the expensive maintenance of a turbine engine. If a rocket-helicopter could have any real advantages (they're certainly cool, but I'm rather skeptical), it would surely be the simplicity of the mechanism making it cheaper to operate.
- Justsignedup 6y agoI think one of the big points is that elimination of the tail rotor could prevent 100% of the tail-rotor failure crashes. So something like 87% of crashes are related to tail rotor failures. So I guess that would be the advantage. Also lighter because you're now missing an entire complex mechanism for the tail rotor and potentially that giant tail.
- pstuart 6y agoIt looks cool but the last update was 10 years ago for PoC?
- protomyth 6y agoSounds a bit like the Fairey Rotodyne which had the same setup using small jets. It was very loud even for the standards of the day. https://www.youtube.com/watch?v=EA3AkvxwS_M https://www.youtube.com/watch?v=EA3AkvxwS_M https://en.wikipedia.org/wiki/Fairey_Rotodyne https://en.wikipedia.org/wiki/Fairey_Rotodyne
- vanderZwan 6y agoSo does anyone know what happened after the last company that backed the project went bancrupt?
- hankchinaski 6y agodoesn't this tiny rocket have very low range and bad efficiency compared to a traditional helicopter engine? the energy density of h2o2 is close to the one of a ion lithium battery (2.7MJ/Kg) vs the traditional gasoline+o2 (13.3 MJ/Kg) [1]. It seems like more a cool trick than something which can replace helicopter engines? [1] https://en.wikipedia.org/wiki/Energy_density_Extended_Reference_Table https://en.wikipedia.org/wiki/Energy_density_Extended_Refere...
- avmich 6y agoNot just regular Li-Ion, but a specific kind, a few times more dense that the regular variety. Is it as easy to get as hydrogen peroxide?
- jeffreyrogers 6y agoYes, you're right. The advantages are that it is much simpler mechanically and can be made more cheaply. But I think it is mostly just a cool novelty. I don't see how these can compete with conventional helicopters.
- basicplus2 6y agobut one is not carrying around a very heavy engine, gearbox and tail structure. (no heavy tail structure because there is no rotational torque from driving the blades around against the tail rotor only gyroscopic precession when changing direction/ tilt etc)
- avmich 6y agoI think Juan Lozano was making peroxide engines for early iterations of John Carmack's Armadillo Aerospace (whose website, sadly, is now only available via web archive...) EDIT: yes, AA is listed as a customer.
- Gravityloss 6y agoAnd very early on, Armadillo actually tested rotors with tip peroxide jets. Only ground tests that I know. Moved to pure rockets quickly. High test peroxide. Mixed monoprops with low grade peroxide and alcohol. Biprops. Peroxide-alcohol? Lox-alcohol? Lox-methane eventually.
- nabla9 6y agoTip jets can use compressed air. That would be more efficient. https://en.wikipedia.org/wiki/Tip_jet https://en.wikipedia.org/wiki/Tip_jet As with all cool concepts "Zee Germans" had the idea https://en.wikipedia.org/wiki/Focke-Wulf_Triebfl%C3%BCgel https://en.wikipedia.org/wiki/Focke-Wulf_Triebfl%C3%BCgel
- MaxBarraclough 6y agoNot all the cool concepts. The Dutch came up with the 'ornicopter': https://youtu.be/0Z2Rr39hiUs https://youtu.be/0Z2Rr39hiUs
- Gravityloss 6y agoThat's ingenious. It's one of those rare mechanisms that are hard to come up with but obvious once you learn of them. I recommend everyone to watch this video. (The presentation spends a lot of time explaining tail rotors, which this invention does not need. Skip to about halfway to see how it works.)
- evilsetg 6y agoA friend just showed me this beast, also using tip jets: https://www.youtube.com/watch?v=dWNq0LSnHLo https://www.youtube.com/watch?v=dWNq0LSnHLo
- 6gvONxR4sf7o 6y agoDoesn't the pitch of a helicopter blade change as it goes around the rotation? With a traditional rotor, the torque is always angular, but with these, the torque will be angular plus a cyclical vertical component, since the rocket pitch is the blade pitch. I'm wondering what the the structural and vibrational implications are of a rocket launching the blade tip up and down at 500 RPM.
- liability 6y agoFrom what I can tell from the images and videos, this helicopter does seem to have a typical swashplate system for controlling blade pitch.
- kevin_thibedeau 6y agoThere is no cyclic. The entire mast is gimbaled.
- 6gvONxR4sf7o 6y agoWow, cool. I wonder if that's a big factor in why the test pilot said it was so vibration free.
- milankragujevic 6y agoWow, I used to make rocket-powered helicopters in Kerbal Space Program a few years ago by putting a "Sepratron" on the tip of the "blade" made from structural wing parts. How appropriate :) See this video for more details: https://www.youtube.com/watch?v=1Sj_jgrokww https://www.youtube.com/watch?v=1Sj_jgrokww
- trhway 6y agomy favorite application of that tech - Roton, a helicopter to space - https://en.wikipedia.org/wiki/Rotary_Rocket https://en.wikipedia.org/wiki/Rotary_Rocket . USSR people know it as "Pepelats" http://copy-cats.work/aircraft02/rotary-rocket-roton http://copy-cats.work/aircraft02/rotary-rocket-roton :)
- app4soft 6y ago> my favorite application of that tech - Roton Rotary Rocket ("Roton") is vise versa opposite design concept to Rocket Helicopter.
- nsxwolf 6y agoHow does the fuel get to the rockets without the hoses getting torn off?
- javiramos 6y agoProbably a rotary fluid coupling [0]. The fluid equivalent of a slip ring used in electrical applications. [0] https://www.dsti.com/rotary-unions/ https://www.dsti.com/rotary-unions/
- tus88 6y agoIt flow inside the wings (yes copters have wings).
- mbrameld 6y agoNobody actually involved with helicopters calls them wings. They're called rotor blades. Similarly, nobody actually involved with helicopters calls them copters.
- Cyphase 6y agoTerminology aside, I think the comment was accurate. I think it would have been better to kindly correct any terminology issues you noticed without saying "nobody actually involved with helicopters calls them" twice. For example: "While `rotary wing` is an accurate term, most people in the industry would probably call them rotor blades." I don't think the "copter" correction was necessary, since that is in fact one of the slang terms for a helicopter and it's clear what they were referring to, whereas 'wing' could confuse someone into thinking of fixed wings on the side. But if you were going to mention it, it would have been helpful to mention what you thought would be a more appropriate term. Just some friendly feedback! :)
- mbrameld 6y agoThe comment was accurate, but the parenthetical came off as arrogant and condescending so that's how I responded. Nothing posted here is necessary. Doesn't change the fact that nobody actually involved with helicopters calls them copters. Some friendly feedback right back at you! :)
- bfuclusion 6y agoFor any HN'ers in the bay area, if you're into this stuff you should pay a visit to the Hiller Aviation museum. It's right by EA on the San Carlos Airport. Hiller was a pioneer in helicopter design, and they have a ramjet tipped 'copter on display. Here's their website: https://www.hiller.org/museum/aircraft-on-display/ https://www.hiller.org/museum/aircraft-on-display/
- Taniwha 6y agoOK, dumb questions - the H202 is entering the combustion chamber at what pressure? below chamber pressure,with a valve, like a pulsejet? or is there a turbopump somewhere? and what powers it? I'm guessing centripetal force once the rotors are spinning helps (but isn't there a potential evil feedback loop hiding in there somewhere?)
- NegativeLatency 6y agoMore fuel -> faster blades -> more fuel Eventually the blades would tear themselves off and end the the cycle.
- Taniwha 6y agoyeah exactly
- stmw 6y agoOne of the earliest efforts of this type was in 1950's, by Hiller Aircraft - and you can see the helicopter itself in the Bay Area, in the Hiller Aircraft museum. It achieved flight and was tested by US Navy & US Army. https://en.wikipedia.org/wiki/Hiller_YH-32_Hornet https://en.wikipedia.org/wiki/Hiller_YH-32_Hornet
- romwell 6y agoThe spiritual successor to Fairey Rotodyne[1] and other tip jet helicopters and autogyros[2]. Hope this one takes off! One of the reasons Rotodyne was not adopted was because it was too loud. Hope this technology solves this shortcoming. [1]https://en.wikipedia.org/wiki/Fairey_Rotodyne https://en.wikipedia.org/wiki/Fairey_Rotodyne
- iancmceachern 6y agoLooks like there are quite a few similar rotorcraft: https://en.m.wikipedia.org/wiki/Tip_jet https://en.m.wikipedia.org/wiki/Tip_jet