Rocket-rotor Helicopters

[Mr. Boltneck]

http://www.popsci.com/technology/article/2010-03/video-rocket-powered-helicopter-could-go-sale-year
Given the fondness around these parts for cruel and unusual vehicles, I thought that this needed posting.

[johnny99]

The copter makes use of tiny hydrogen-peroxide-powered rocket motors on the tips of the blades, which replaces the traditional engine-powered rotor. Large fuel tanks surrounding the pilot allow the Dragonfly to travel at up to 40 mph for 50 minutes.

     Eeeep!!!
Holy hell. There is a really grim death waiting to happen. BTW, somewhere I still have the original plans for the pulse jet version.

[pakled]

(warning - didn't read the article... The Nazis experimented with one, and the US a bit later, but the whole idea seems a bit dodgy...

[Matthias Gladstone]

Here you go:
http://www.helicoptermuseum.co.uk/images/gallery/djinn-2.jpg
Succesful aircraft, used by the French. The exhaust from the turbine was directed along the rotor blades, coming out at the tips and causing the phenonama known as spinning to occur.
-Matt

[Mr. Boltneck]

I keep going back and forth on which is more risky: being strapped into an ultra-light helicopter next to conventional fuel tanks, or between two sizable containers of H₂O₂. I am assuming that this is a fairly concentrated peroxide mix, since rockets usually operate on something above 70%, and often around 90% peroxide, in my understanding.
An oxidizer like that is fairly tricky to handle, albeit safer than most rocket fuels, and I suspect that this may restrict the adoption of these machines a bit, since a specific storage/handling license is needed in a lot of places.

[johnny99]

 I work with large quantities of 30% from time to time, which is nasty enough. The over 70% is just scarry as hell! Although I do love it in theory as a power source in specialized apps. At one point I was seriosly working towards a grant application from D.A.R.P.A for powered exoskeloton research powered by concentrated H2O2.  If you do a little bit of research into the bell jet belt, you find that procurement, and smallscale manufacture are both huge hassles. But the biggest problems are in safe storage and handling. For the military, sure great. For private individuals, not so much.

[Mr. Boltneck]

Yup, scary stuff indeed. Around here, some buildings have storage tanks of the high-percentage stuff, along with cryogenic tanks, and gases like silane and fluorine. Given that this is a seismically-active area, those could be overly-exciting areas to be in during a larger quake! Plus I'd hate to be the driver on a tanker truck-full of strong peroxide, since if things go badly pear-shaped in a crash, it will mean a high concentration of oxygen around hydrocarbons at elevated temperature. If I had one of these helicopters, I think I'd get a special fuel shed built, well away from everything.

[johnny99]

What I would really like to see in this vein, is something simular to what I proposed in another thread recently.  specifically, given the power density of concentrated H2O2. A more or less conventional IC driven gyrocopter fitted with peroxide catalyst "jato style" self contained rockets on the rotor tips. (For use on takeoff/landing/hovermode as the situation dictates). Giving you VTOL and possibly limited hovering capabillities, With out the added complexity of a true helicopter. Since you could either use sealed clip in style fuel cells, or dismount the whole unit. The risks associated with conventional fuelling, etc.. Would be greatly reduced. As an added bonus, Should a fuel cell rupture or simular incident occur in flight, centripedal force should ensure you don't end up covered in H2O2.

[pakled]

I remember that they tried H2O2 in one of the smaller Nazi jets (the rocket one, I seem to remember). One mission failed as the fuel sprung a leak and dissolved the pilot. Gruesome.

[phuphuphnik]

Not so much dissolved, as I recall he just caught fire. That would be the Natter, Tstoff and Zstoff were the fuel components.

http://en.wikipedia.org/wiki/T-Stoff

[Mr. Boltneck]

Yeah, you have to love that kind of thinking. Hey, we already have a dangerous oxidizer, let's throw in hydrazine! They tried some of these hypergolic-mixture engines for jet aircraft in the US early in the Cold War, but gave up, as they were just too much trouble to maintain, fuel, and operate for most purposes.
A lot of people forget that while oxygen is vital in moderate amounts (at least for air-breathers) it is incredibly dangerous in high concentrations. In the presence of a high partial pressure of oxygen, oils can combust at room temperature. And if you are in the presence of decomposing peroxide, you are at much greater than room temperature.
So this helicopter is no safer in that regard than one operating on gasoline.

[hardlec]

Hydrogen Peroxide was used out of desperation in WWII, because allied strategic bombing targeted Nazi fuel sources:  the oil fields, the refineries, the infrastructure to move oil and later fuel about. 
Gasoline is Toxic, corrosive and seriously explosive.  I wonder how dangerous Hydrogen Peroxide must be.  I am also rather more curious as to what has been learned in the last 60 years as to making the fuel more usable.

Still, I am more curious about how many good ideas were killed because bean-counters of various types refused (and pretty much still refuse) to accept any power source that is not a piston internal combustion engine. I continue to hear criticisms about the fuel consumption of the Abrams Tank, which has an incredible combat record.  The turbine engine Chrysler marketed in the 1960s, with some 2010 updates, would probably be great paired with an electric motor in a hybrid. 

I do believe that projects in the 1950s showed that the technology of the 1950s was not up to the task of powered rotors that used jets or rockets on the rotor tips.   

I'd really like to see someone look at some of the old Horton designs and see what can be done with "unlimited" access to materials.

[johnny99]

Hydrogen Peroxide was used out of desperation in WWII, because allied strategic bombing targeted Nazi fuel sources:  the oil fields, the refineries, the infrastructure to move oil and later fuel about. 

Wrong, Z-stoff, was used because it was a very high( energy) density fuel, and worked great as a monopropelant. Considering the logistics of manufacture, storage, and transportation. The thought of using it out of desperation to replace petrol is laughable.

Gasoline is Toxic, corrosive and seriously explosive

I suspect you don't actually understand the word explosive. And I know you don't understand the word chauvinistic.

I wonder how dangerous Hydrogen Peroxide must be

Very! Although unlike gasoline It isn't explosive.

Still, I am more curious about how many good ideas were killed because bean-counters of various types refused (and pretty much still refuse) to accept any power source that is not a piston internal combustion engine.

Quite a few, Because an IC engine was a better choice.

I continue to hear criticisms about the fuel consumption of the Abrams Tank,

Really, from who I wonder? No doubt Whomever it was didn't understand that fuel economy was not a main design criteria for a mainline battle tank!   

I do believe that projects in the 1950s showed that the technology of the 1950s was not up to the task of powered rotors that used jets or rockets on the rotor tips.   

Disregarding all the different designs that were actually built and flown of course.

I'd really like to see someone look at some of the old Horton designs and see what can be done with "unlimited" access to materials.

I'm not sure about Horton? I suspect you actually meantHiller In which case I think you will find, that if you actually read the thread. That is exactly what is being discussed.

[markf]

I suppose if he spends enough time defending his lack of knowledge eventually something gets said which is factual. In this case Mr J99 he got one right and it is the Horten, a failed attempt by the Nazis at the end of the war to build what we would call today a stealth aircraft.  The only remaining piece of their work is the fuselage, a bit down the road from me in the Smithsonian.  Of course all his spurious threadjacking 'facts' continually being raised to hide any semblance of aerodymanic knowledges which require we BG members to continual correct are not germane to Mr Boltneck's the rocket tipped helo topic, so we'll do the best we can to keep it factual. markf 

http://euronews.us/?p=1993

[hardlec]

The Germans used Hydrogen Peroxide because they were looking for options to petrolium.  They also tried steel tyres, and there was even a coal-fired aircraft.  The danger associated with this stuff has prevented it from being used as a fuel in other applications.  T-stoff, BTW, is generally a rocket fuel, not a jet fuel and certianly not appropriate for a piston engine.  It was used in the ME-163 Komet, and IIRC, this plane was notorious for killing more of it's crew in accidents than in enemy action.  By advocating for T-stoff, you are proving your own chauvanism for the piston engine.

A thing is explosive if it is able to cause explosions.  Gasoline is injected into a cylinder with air and ignited.  The resulting explosion drives the piston.  Gasoline fumes can create a very dangerous fuel-air explosion.  Explosive it is.

Chauvanism is keeping to an ideal or belief when it has been disproven.  Male Chauvanism is keeping to the belief that women are inferior when that has been shown to be false.  The Piston engine is a dead-end technology.  It is extremely convienient because it is availible. On the other hand, where "convienience" is not a factor and performance is, the turbine seems to be a frequent choice.   

In the 1950s, prototype "jet-tipped powered rotors" were flown.  There designs showed proof of concept, but the designs were two "complex" for production.  It is possible that with current availibility of materials and production technigues, the concept could be re-visited with more success. 

[Mr. Boltneck]

*Ahem* While gasoline and other such mixtures can explode, given the correct fuel-air mixture and dispersal, if the mixture in your engine cylinder is exploding, in the sense of detonation, you have a serious problem, which will shortly resolve itself by damaging your engine into inoperability. If you are a fan of the Mythbusters show, you may have seen their attempts at getting car fuel tanks to explode as seen in the movies, and it turns out to be surprisingly difficult to get beyond burning, unless you get some help, generally involving explosive charges.
As has been mentioned elsewhere on this forum, there are fundamental engineering and safety issues of one sort or another any time you have a large amount of stored potential energy of any kind in a relatively small package. It does not matter if this is in an electrical, electrochemical, chemical, pressure, or plain old mechanical form. Each has its benefits and each has its attendant risks: shock, explosion, fire, oxidation, toxicity, kinetic violence, and so forth.
Likewise, I have never seen anything which convinces me that there is one "universally correct" motor or prime-mover system. Despite their potential problems, plenty of firms are building a wide variety of Stirling- or Rankine-cycle heat engines, for a huge variety of tasks, including solar-power generation, biomass combined heat/electricity cogeneration systems, and so on. But these are conspicuously absent from, say, commercial aviation, which primarily uses the turbine in some form or another. Likewise, we are seeing a huge amount of development in all-electric personal transportation, but no plans to replace Diesel-engine internal combustion in long-haul trucking, even if it becomes part of a hybrid powertrain, and runs on a biofuel.
So condemning an entire broad category of technology as a "dead end" makes no sense to me from any sort of standpoint. There are better and worse choices which need to be made, technologically, environmentally, economically, etc. There is no one-size-fits-all solution, unless and until someone invents a storage and propulsion system of a kind unknown to present-day science.
Some choices are simple. If I decide that, let us say, I want to build an external-combustion-engined moped, about the only thing stopping me is a bunch of homework and development: not easy, but not impossible. A moped is hardly a demanding platform. If I declare that I will develop a Stirling-cycle light-aviation engine, I am committing myself to, at a hazard, a minimum of ten years of hard work, with a team of experts, and I will have also assumed the burden of proving that not only can my firm's engine develop the necessary power for the weight, but that it is more economical to operate and maintain, and, most importantly, that it is safe and reliable enough to be certified for use in aviation. So, maybe, I either don't develop for aviation, or I choose a development path which doesn't use a Stirling engine, but concentrates on an aviation-grade supercapacitor-based electrical storage system.
Sometimes, developments simply have to wait for changes in completely separate fields, too. As an example, when I was working on my BS in engineering, back in the early 1980's, the concept of a hybrid powertrain was a topic of considerable interest and discussion. Commercialization, however, was dependent on a variety of improvements. Not just in battery technology, although that was important, but in computational power. An expensive desktop computer (more or less the only sort) of the time typically had far less power and RAM available than today's netbooks, and took up a big, fan-cooled box under the desk. Now, heck, everything needed to manage a parallel- or series-hybrid powertrain can reside in a few little sealed boxes, and cost only a fraction of the total purchase price of the vehicle.

[johnny99]

The Germans used Hydrogen Peroxide because they were looking for options to petrolium.

This continues to be wrong. To put it in terms anyone can understand. That would be the equivelant of using gold to replace bricks as a building material.

The danger associated with this stuff has prevented it from being used as a fuel in other applications.

You mean other than the helicopter that started this dicussion,The V-2 german rockets,the British black night Rockets that they used for their only succesfull satelite launch, The bell jetpack, and all the different helicopters,planes,submarines,and torpedoes that have used it as a propellant?

T-stoff, BTW, is generally a rocket fuel, not a jet fuel

Yes? I'm pretty sure everyone else conducting this discussion is aware of that. Are you just now finding it out?

and certianly not appropriate for a piston engine.

Odd, Prehaps you should inform the Swedish navy. Since their torpedo 2000 manufactured by SAAB underwater systems uses an H2O2 piston engine.

By advocating for T-stoff, you are proving your own chauvanism for the piston engine.

This makes less sense than most of the things you say. If i'm advocating what you feel is a rocket fuel, then i must be pro-rocket engine. So what has that got to do with supporting IC engines?

A thing is explosive if it is able to cause explosions

This Also continues to be wrong! By your definition Bisquick is an explosive Prehaps you Should inform the BATF

Chauvanism is keeping to an ideal or belief when it has been disproven.  Male Chauvanism is keeping to the belief that women are inferior when that has been shown to be false.

Main Entry: chau·vin·ism
Pronunciation: \ˈshō-və-ˌni-zəm\
Function: noun
Etymology: French chauvinisme, from Nicolas Chauvin, character noted for his excessive patriotism and devotion to Napoleon in Théodore and Hippolyte Cogniard's play La Cocarde tricolore (1831)
Date: 1851
1 : excessive or blind patriotism — compare jingoism
2 : undue partiality or attachment to a group or place to which one belongs or has belonged
3 : an attitude of superiority toward members of the opposite sex; also : behavior expressive of such an attitude

— chau·vin·ist  \-və-nist\ noun or adjective

— chau·vin·is·tic  \ˌshō-və-ˈnis-tik\ adjective

— chau·vin·is·ti·cal·ly  \-ti-k(ə-)lē\ adverb
Sorry, wrong again!
Pardon me, as I must dash. I will be happy to continue your education when i return

[johnny99]

PART TWO (pardon the double post)

The Piston engine is a dead-end technology

Just ummm.. WOW?  I'm not sure what to say to that statement!!

On the other hand, where "convienience" is not a factor and performance is, the turbine seems to be a frequent choice.

Disregarding your questionable assesment of convienience, yes this is true? Whats your point? I don't belive myself or anyone else was disparaging turbine engines?

In the 1950s, prototype "jet-tipped powered rotors" were flown.  There designs showed proof of concept, but the designs were two "complex" for production

Stop trying to be clever, your not good at it. the response was to your original post which read

I do believe that projects in the 1950s showed that the technology of the 1950s was not up to the task of powered rotors that used jets or rockets on the rotor tips.

I went ahead and underlined the relevant parts of your originalpost.
The technology of the fiftys obviosly was up to the task, since thats when they succesfully built and flew them. As to  jets and rockets being to complex to use @ that time . The whole point of the development of rocket rotor helicopters was that  they are simpler.  i.e. Complexity was not the problem, noise, range and payload (efficiency), shear loading at the nacell coupling, and dangerous autorotation characteristics in the event of power loss were and continue to be problems in the design of this type of rotorcraft.

I'd really like to see someone look at some of the old Horton designs and see what can be done with "unlimited" access to materials

My appologies for the missunderstanding. I was under the impression we were discussing helicopters(Thanks to Markf for the catch). As to your "flying wing" built with modern tech, and unlimited access to materials. YOUR WISH IS GRANTED! google Northrop Grumman B-2 Spirit.  

In summation, not only do you appear to know absolutely nothing about the design, and technology  of aircraft. But your willfull ignorance about these things is becoming quite tiresome. If you wish to have a discussion on the subject (and most assuredly if you wish to build your own aircraft.) , is it really that painful to educate yourself on the subject first?