Open head rocket : huge efficiency at bullit train speeds?

[Cloxxki]

Hi all,

I have an idea for an über-efficient high-speed vehicle.
Cutting out overhead surface area all together.



Main features:
- rougly cylindrical craft shape, like an open head rocket
- payload is hidden behind air intake, and adjacent to smaller internal engine)
- air intake surface makes up ~100% of the frontal surface area
- exhaust pipe surface makes up ~100% of the front surface area, good diffuser for effiency, air naturally expanding back to ambient conditions
- Intake air is sped up/compressed to fit through much narrower channel, say 10-30% of vehicle's frontal surface. Keeping the outer shape cylindrical (cross section shaped for optimal intake+compression), this frees up significant space.
- Prop or jet system. Anything good at thrusting air.
- Prop version could well run be run electric. Grid, battery, or solar. Train version could be gravity assisted for acceleration, with the engine for cruising (resisting decelleration) only.
- Really, it's an open head rocket. Think about it.

Vehicles can be made to work as:
- (Maglev, ground effect or semi-traditional track) trains
- personal vehicles, ground effect.
- all-inclusive aircraft only needing additional aerodynamics for lift, not payload
- superspeed underground train. No issue to get it through a tight fitting tunnel, as it digs more than forces. Alternative to gravity assisted (deep track, high station, vacume tube systems?
- underwater crafts? Obviously, thrusting water which doesn't compress well, water will travel at high multitude of craft speed through the narrower inner channel and engine.

My questions to you:
Is there easy-to-access data or formula on the efficiency losses of compressing/speeding up air through a smaller duct, and then allowing it to expand back? By lack of overhead surface area, hardly any nett thrust would be required for cruising. Compression should cost little more than the expansion offers back? Perfectly designed inlet and exhaust shapes should get air drag at bullet train speeds to an absolute fraction of what trains use now.

My threads usually don't get any replies. At least just tell me something rude?

[Shadesz]

interesting idea. If it was used as personal vehicles... we would have no birds left in the world.

[Rubberband]

Wheel

Hello Shadesz,.. this is that thing that I asked if you animate....
Title07.mpg - YouTube

[Cloxxki]

interesting idea. If it was used as personal vehicles... we would have no birds left in the world.

Depends on the engine. Bird could end up shaken, bit not too stirred.
If the engine doesn't need to offered too great a torque, environment and parts inside the engine may not be all too leathal.
If only we could thrust air as if it were magnetically charged particles, through a Rodin coil of sorts. No moving parts.

As a follow-up, I figured such a vehicle could use a shaftless propellor. Turns out this was awared a patent only in 2007, by some fellow Dutchmen. Can you believe that, this century? I've seen wind turbine designed with shaftless cones, perhaps those were different enough to allow for a US patent of the shaftless prop. Anyway, I'd preferrable float such a prop inside the vehicle, from magnets of course. It would be a floating electric angine shaft. Of course. It could be one part, wide at the front to efficiently compress air as it comes in, and expand it on the way out. Ultimate torque from barely moving the air apart from laterally compressing it. I could add a shaft as to not infringe, but it would take away from the efficiency greatly.

I may be in touch with the owners of the shaftless prop design to discuss my (now open source, oops) enhancements of their design. I already managed to obtain definite contact details. It's surprisingly simple and logicaly to have a shaftless prop. With current knowledge of magnetic levitation as bearing substitude, in combination with modern electric engine technology, it should be overwhelmingly efficient.

I am trying to grasp the kind of air drag my vehicle would be dealing with. This coud be compared to a solid cylinder of the same size, a cylinder of the diameter of the inner air duct, but I think is will be less still.
Since the narrow air shaft is the length of the vehicle, and even the air intake and exhaust could be part (all one moving part) of the propulsion via a floating prop, I think that although for the applications I am currently looking at will require minimal torque, the torque may actually proove for be out of this world for a low-speed prop design. It may even be applicable for supersonic (yes, electric power) travel, using very deep blades on that shaftless prop.

Imagine the vehicle being 3 meters across (train size)
Overall length 25 meters.
Inlet and exhaust nozzles each 5 meters to go to 1.5 meter air duct and engine core, and back to 3.5.
If a shaftless prop is 15m deep, and has just one or a few "winds", it could spit out air at supersonic speeds, at very low rpm. I must correct myself, that the air in the thin shaft will not only be compressed but likely also sped up. Any knowledge as to natural ratios for this to occur would be most welcome. Compression is good for traction of the prop, speed is inconvenient for a prop. With the train going 300kph, the air inside would be going supersonic.
When standing by the train tracks though, as it passes at 300kph or even 600kph, the environment would be effect little more than a 3m across thin walled sevage pipe zipping by. And aircraft of such cconstruction could be very silent, at close range, and offer unique acceleration and braking capacity.

For home builders (I have 2 left hands) a prototype would be relatively easy to build from soda bottles. The necks as nozzles, a bit of pipe as thin air duct, and the outside of a bottle as main outer cilinder shape. Not sure what engine to stick in there. Some handy work might in fact make a crude deep shaftless prop and shaft in one. Floating it magnetically is optional, 2 times 3 ball bearing can do the trick of suspending it.

2 cylinders stuck together, counter rotating, would make a nicely balanced aircraft hull. Frees up some payload space laso. Lift could even be (partially) generated inside the nozzles and/or tight air ducts.

All ideas are welcome!

[Slider2732]

I don't fully understand the thrust generating part yet, but am looking forward to a working example !
On seeing this, the immediate thoughts were to super-speed iron rich particles through the assembly. The magnetic field accelerating those particles, which return back to the front by the reducing power of their own inertia and are captured by a field intensity at the output nozzle.
If such a system used HV with the magnetism, from an onboard Tesla tower, then a plasma ion wind of great potential 'may' be created (ionboard was the spelling mistake that I just made lol, not a bad name for the system though).

Few parts, great output....now 'll try and understand it a bit more with a reread !



So you'd use a venturi effect to spin the wind ?
Counter rotating on aircraft - very nice Imagine a DeHavilland Mosquito for the 21st century.

Actually, wait a minute. If you know anything about Willard Custer and his line of 'its not the airspeed its the speed of the air', then you can see that the generated lift of the airflow through the system would add lift to the body of the aircraft. As the wind moved along the thrust chamber, spaced lattice holes on the top chamber surface would allow the air pressure difference that created the wonderful extra lift that my own model of his design experienced.
Here's some Custer info:
Willard Custer -- Channel Wing Airplane -- 10 Articles & 30 Patents
Here's a video of that one and I hope it helps with what i'm thinking:
ChannelWing - my plane with no wings ! - YouTube

So, for flight, we'd have extra lift generated through your design there Cloxxki

[Cloxxki]

I don't fully understand the thrust generating part yet, but am looking forward to a working example !
On seeing this, the immediate thoughts were to super-speed iron rich particles through the assembly. The magnetic field accelerating those particles, which return back to the front by the reducing power of their own inertia and are captured by a field intensity at the output nozzle.
If such a system used HV with the magnetism, from an onboard Tesla tower, then a plasma ion wind of great potential 'may' be created (ionboard was the spelling mistake that I just made lol, not a bad name for the system though).

Few parts, great output....now 'll try and understand it a bit more with a reread !



So you'd use a venturi effect to spin the wind ?
Counter rotating on aircraft - very nice Imagine a DeHavilland Mosquito for the 21st century.

Actually, wait a minute. If you know anything about Willard Custer and his line of 'its not the airspeed its the speed of the air', then you can see that the generated lift of the airflow through the system would add lift to the body of the aircraft. As the wind moved along the thrust chamber, spaced lattice holes on the top chamber surface would allow the air pressure difference that created the wonderful extra lift that my own model of his design experienced.
Here's some Custer info:
Willard Custer -- Channel Wing Airplane -- 10 Articles & 30 Patents
Here's a video of that one and I hope it helps with what i'm thinking:
ChannelWing - my plane with no wings ! - YouTube

So, for flight, we'd have extra lift generated through your design there Cloxxki

Thanks for the response Slider!
Venturi could be used to generate lift I suppose. I haven't gone into detail on how to compress/speed up the air to go through the tight duct at ground speed. A spinning part seems hard to go without, until we get proper shape shifting going to scoop up air.

Man, great mind do think alike! I was thinking of magnetic particals as well, to be let go on the front and harvested at the back. Snow flake shaped for uptimal air scoop properties, I suppose. The thrust on the recycled particles would nettt zero by having to circulated them, but they could be made to move more air going through a thruster. This is currently outside my core design though.

The thrusting would be a prop where the blades are not on a shaft, but inside a cilindrical ring, pointing inwards. I can't claim this as my invention, although I've had this in my head for years.
Shaftless Propeller

Best image from the patent:


Currently I like to think of the prop more of a drill bit with very little "meat" to it. Imagine the pictured prop, but taking it from a wedding band shaft enclosure to a deep cylinder.
Visual aid: Lamp that turns a wind turbine inside out to utilize LED-technology
I'm sure I saw a wind turbine design on a forum recently, with ring mounted fan blades, leaving the core of the stream untouched. Same as the shaftless propellor patent, just as an encapsulateed wind turbine. That's what gave me the idea for the perfect thruster in my design.
The pain in such axleless designs (motor and bicycle wheels exist) is the extensive bearing assembly required. That's why I want to suspend it all. Some well-placed neodyniums in ring pattern should balance it nicely. Some coilwork on teh craft and magnets on the prop should make it a one-part propellor.

Integrating the thruster, intake, throughput and exhaust should keep some aerodynamiccists busy for a while. A lot can be done in varying the girth of the duct, and the throw of the blades in each section. It will just all share one fixed relative postion and rpm.

Indeed it is important to realize that when my verhicle is at cruising speed, the air inside the vehicle will barely be displaced. Exiting the exhaust, it will have no ground speed at all, of course in still wind conditions.
The main objective of my thought exersize, was not to get a thurster per se, but an aerodynamically "invisible" or "super slippery" craft.

Let's take this to the absolute limit of our current aviation ceiling.
Concorde.
Replace it by two counter rotating open head rockets, and retractable (F14) style wings. Even with very modest throw on the prop fans, supersonic speeds might be easily attainable. I am even wondering whether Mach1 will for a significant hurdle, the vehicle barely having a frontal surface to mention. There is no vacume behind it, just an air twirl.
Power and fuel source would be interesting. Batteries seem a stretch even in a low drag craft.

Willard is new to me, thanks!
I immediately found a loosly related design to mine on Youtube: NASA Spiral Duct ESTOL Concept - YouTube

[Slider2732]

The NASA concept is a cool looking small craft...it may have troubles with any power-out condition, but other than that deserves thought for a commuter aircraft.

Concorde was THE definitive high speed delta wing, in my opinion. Saw the last one into Manchester Airport and the last one out. Took my kids to see the last flight into Manchester and even though they didn't really know what the point was, now do say they saw a Concorde fly (haven't heard any more recently about the 2012 Olympics fly past idea).
So, the Tomcat wings may not be a factor of need...modelling a flying wing based on Horten brothers 'bell shaped' lift criteria or that of Alexander Lippisch, or indeed Northrop's WWII aircraft can bring incredibly stable flight at take-off and landing speeds.
Perhaps as an example of slow speed handling with flying wings and delta wing shapes, I might bring in another of my video's, simply showing a backing up of my waffle here, rather that it just be speculation from a chair lol.
Here's my Northrop XB-35, 10.5g, outside, didn't flinch with wind and the yaw was very nice and controlled at whatever speed it flew at (no vertical surfaces). Sorry about the rubbish quality again, didn't get a good camera til the start of this year:
XB-35 10.5 grams - YouTube

Point being - flying wings and delta's are very stable, when designed to certain principles. Principles that I believe your system can benefit further, if counter rotating units were fitted. Such a platform, would allow the engine to sit along the center-line, or have 2 of them, positioned either side of the central section. The system could employ a Custer Channel Wing method at the Cg (Center of gravity) location, where own built flying wing designs have benefitted and just after which the efflux would exit.
The Horten IX springs to mind as a shape now - but also the Horten IX with a tail, that Richard Keller designed during WWII. Here's *cough oops another video* my similar design, flying around and that could be converted with a LOT of research work, as a platform to try your idea in a working model:
Eteel-18 maiden - YouTube
That's my envisaged testbed model, to be upscaled for powerplant testing

On to thrust shapings. The inlet could be designed and shaped to cause the venturi swirl. Actually fabricated, like a rifle barrel of a gun is swirled.
That would negate the need for an inlet fan or other gubbins.
However, a Tesla Turbine might work well, at least it's a consideration..
On the exhaust end, EDF assemblies in model R/C aircraft have an outlet that is approx 90% of the inlet diameter. This increases the efflux speed (wind output speed).

For a railway system - Maglev sections at the stations would accelerate the train to a speed at which the system would take over. Think Ramjet engines. On approach to the next station, the same Maglev system would enable train braking.

[Cloxxki]

Thanks slider, you bring a lot of aerodynamics knowledge to my little brainfart.


About the maglev trains. I appreciate maglev propulsion greatly, and the idea to have a maglev launch to cruise speeds, or any significant hills to conquer, is a minimalist idea by itself. Hey, if it's good enough for 120mph rollercoasters...

Being a green energy proponent, I would prefer to replace the maglev propulsion track by a hole in the ground. Steep hill down from the station, let gravity do the work. Reach bullit speed, and transition to level. Cruising propulsion to take over, until the destination is approached, and gravity acts as a brake.


I think I'm starting to appreciate my own idea a bit better thanks to your insights. When incorperating an open head prop rocket into a flying though, does it not efffectively replace a typical integrated jet?
Yes, the open head rocket may have some traits such as high torque, but I think its main quality is that when used without wings at all, of minimalist wings at that. Brutal speed, nothing subtle or moderate. It is of course a null frontal surface thruster, meaning it will work best when actually combined with limited additional frontal overhead surface. Trains and rockets are the ultimate applications.
An advantage the open head rocket could in fact offer, is the limited space taken from a flying wing's interior. And if the engines work out nicely for it, perhaps a lightweight engine may proof efficient for propelling a large craft. I can just hope for such parameters, can say I expect them right now.

You'll agree that flying wings are operating at relatively low speeds for their size, they're oftentimes all lift? Concorde, I may understand it wrong, got it's lift from brutal speed and minimalist wing surface.
If open head rocket would proof viable as a supersonic engine for a Concorde type craft, regardless of fuel source, it might do so at a fraction of the fuel consumption Concorde required.

It would be great if the shaftless prop would not require an inlet and exhaust part to work effficient, and could suffice having shaped inlets to get the air to twist and compact smoothly into and out of the nozzles.
This might then assist A- in generating lift and B- allow the front to back air duct(s) to be placed out of the way. Decentral from the payload, to be less intrusive to interior design.
While I certainly like the propulsion going directly through the COM of a vehicle for stability as you said, perhaps shifting the actual path of the air stream off-center may not harm too much, when taken well into acccount in the design.

Could someone please offer thought on the concept of a deep shaftless propellor, possible with drill bit type throw to it, resulting in either extremely high speeds or very low rpm's? Especially how this would work in conjuction with an integrated electric engine design.

I am an avid fan of Rodin coil research, but believe the spin created thusfar is usually not apt for twisting shaft inside the coil, the spin created is lateral, very impactical for propulsion. If a Rodin coil could do the axle turning job, the toroidal shape and the way winds go back and forth between in and out, to be radi(c)ally different. Hope I am wrong on this.
Else a typical electrical engine will do just fine turning this prop. Yes, the prop will be heavy. But it would offer preferred gyro action. And might work at low rpm anyway.

[Slider2732]

The gravity model could certainly be trialed at a scale sizing, proof of concept sort of thing...but maybe impractical for inclusion in a rail system. I dunno actually, plenty of gradients on railway lines and some may indeed be suitable right as they are.
The thing about the Maglev method, is that the train itself would supply the magnetic forces. The electromagnets energize the track equipment. Regenerative effects would assist the powerplant electrical operations, same as the technology used in cars. A trains mass being much greater than a car, the huge regenerative effects could lead to sizeable power delivery.

Replacing a jet engine is part of my thinking yeah...at some point, all those Boeings are gonna need to be powered by something other than jetfuel !
Mainly, weight considerations will play out for airborne versions.
Starship coils, Tesla HV energy and more, *should* be able to bring in a surprisingly lighter than expected power delivery system. Especially if one wire electrical systems are utilised.
Plasma rockets have always been low powered, move a spaceship in deep space vacuum type territory. However, with accelerated airflow principles linked to jet design, we could build upon a proven model.

An open head rocket under each wing section is my envisaged deployment for flying wings. That way, all the interior space is still available. The landing gear would sit under the engines, which being of envisaged similar sizing and shape to the Rolls-Royce Olympus 593's of Concorde, would enable good emergency landing characteristics. A flying wing is inherently a good glider, another safety aspect. Btw, they have the full speed range of any other aircraft. Most is about less clutter and why the Northrop and Horten wings having no vertical surfaces aids raw speed (most people view them as unstable, they're definitely not). Arguably, the most rigid, tough, fastest platforms look like boomerangs

You might like this - a jet powered model, looking similar to your Concorde delta shaping. 366mph !
Very, very, very fast Turbine powered RC Jet - YouTube

You're the Frank Whittle here, so i'll take my cues from you lol

[Cloxxki]

It would certainly require dedicated tunnel drilling. Possibly near types of tunnel engineering, to go as deep as hundreds of meters below station level.
The gravity part doesn't need to be tested of course, we know pretty well how that works. A tunnel shape and rail/maglev interface need to be really tight though, fail proof.
A scale model would only need to be put on a fast car to test the dynamics of the engine. Perhaps a scale model with only an air flow meter in the exhaust could offer insight to the losses involved?

[Slider2732]

I'd imagine that the very first step would be to build something, then get the ideas tried out and along the way to research traditional jet engines and rockets. Refine, combine, dismiss, return to dismissed ideas lol...actual builds. Too many such fine ideas don't make it past contemplation y'see.
So, in my opinion, build a test structure...do the tests on a roofrack of a car and then try the same with the magnetic assembly situated. Etc, etc and building up some good solid understandings as work evolves.

A wind tunnel isn't unrealistic. I haven't built one yet, but intend to and several ideas are floating around for home built ones - "Flights of Inspiration" Make a Simple Wind Tunnel
(if you smoke, you've got a way of visual airflow testing !)
and, this sort of thing is cheap and easy (looks like being what I will do) -
How to build a homemade wind tunnel? - YouTube

.

[Cloxxki]

I have to agree.
But: no shop, no tools, no money, no skills (beyond that of a bicyle mechanic), don't smoke, don't have a car. Can't even get my phone to load, let alone build an electric motor.
My abilities and capabilities are mostly limited to concepts, and thus open source is my platform to share. Some of my concepts and designs have made it to reality, for which I am very grateful.
I will make my hands dirty, but cuttting bottles and duct taping them together are the upper band of my limitations right now.
Greatly admire those who do build though, and would love to sweep the floor for a local builder, to be able to look over the shoulder.
I have some skillful 3D engineers as friends, and via them access to machine shops. If I know the math will work, I may get a simple prototype together. It would need to be without any wiring or programming, or I need someone to handle that for me.

While plastic 2L bottles may be convenient to work with, perhaps their frontal surface is on the lower band of being practical for proto testing?
The widest PVC pipe, for plumbing, might be nicer to work with in terms of math and measurements, and more sturdy to build with.

Stupid question: can model rail track be converted to Maglev? I mean, can current on the tracks repell magnets aboard the OHR to make it float?
Just looking for a scaled test bed. A wind tunnel would be great though, as it can be calibrated, and measure thrust. Quick calcs would come to reliable performance figures.
Would be awesome to see how much power is would take to overcome air drag at cruising speed, reach zero thrust. Say an OHR 1 foot in diameter, 5 feet long, at 40 or 60mph. Easy to compare with a same size optimized cigar (measure drag at given air speed).
And then get the OHR to thrust beyond its cruising speed, see how much torque it generates for additional power input. Implying either overhead friction, a hill to be negotiated, or acceleration to be sought.
A good aerodynamics engineer could figure most of this out on the computer though. They build airliners this way.

Who'd we want to consult?
- Venturi designer or best practice guidelines for nozzle geometries
- Bedini / Rodin motor builders
- Thruster prop engineers.

Slider2732,
For adding an engine under your flying wings, I suppose the bottle neck inside to created space, is not as necessary, or to a much lesser extent. You'd just want to create space for an engine housing with drive coils, right? Also, you'd want significant thrust to overcome drag on the wing itself, so a simple cylindrical shape may not cut it. You may indeed need to squeeze the exhaust as you well understand. It will add drag to the engine enclosure, but may well be worth it for thrust effficiency. Heck, even in my applications, I may not get around that. I don't understand aerodynamics sufficiently right now to be sure.

At which air speeds does an engine turn from being being air cooled by it's self created air flow to requiring additional cooling? A thin open cylindrical engine may cool just great, up to a given speed. Pretty sure the break even is at super sonic speeds?

If you are looking to build a shaftless prop (remember, there's a patent out there) engine, first proto's don't even need to be magnetically suspended. A ring of ball bearings or even precision bearings on springs supporting a round interface should do fine. Especially of the prop gets a long throw to work at low rpms. I may be overlooking huge issues merely suggestion this, but I like low rpms here until someone tells me not to.
If you ask me, I like your idea of a central (double) air duct in a flying wing most. Limits air drag, nothing sticking out from underneath. Just bulge the wing's a shape around the inlet a bit more to get some good lift there as well. The inlets are invisible for air drag anyway, get some extra free directional stability from it :-)