Greetings /sci/!
It's been a while I've posted updates and surely a lot have happened meanwhile. We are the Hyperloop Student Competition Team of /sci/, although our team have changed quite a bit - most of our members went away but I got to replace them with others. Anyway, we have a Prelim Briefing Submission coming up and we've pretty much covered our main design features.
I'm here today to do a sanity check - to see if our design ideas are actually valid or not. So before you start saying >he does it for free, let me remind you that this thread is not for recruiting, but for brainstorming for us to have a good and constructive time together.
Please feel free to comment, criticize or advice! If you'd like further correspondence, email at
>[email protected]
First up: Bogies & Carrosserie Design
At the head of the Hyperloop Pod, it's marked as a compressor, but we have yet reached a concrete decision on what kind: it's one of the subjects I'd like to ask you guys tonight.
There are 4 bogies, on each 8 sets of hover engines for magnetic levitation, and an air bearing system that allows the pod to slide over the guidance rail with minimal friction. There are linear magnetic brakes (rollercoasters) involved, although the hover engine also has its own braking.
2: Levitation / Propulsion
In all the Hyperloop designs available out there and the further reports & analyses that cover the original white paper by Elon Musk, the compressor and the subsequent air bearing system is the design imperative. The piston effect which occurs within an enclosed tube is one of the main challenges a train speeding near 1 Mach would face, hence Musk proposes a compressor which sucks in the air that accumulates at the front of the train. This air is passed through a compressor, and thus sent to the air bearings that provide the levitation, the end nozzle that is the propulsion and the life support systems of the passengers inside.
Our proposed solution is to employ a combo magnetic - air bearing system. Air bearings are very experimental and certainly not employed at the speeds of proposed Hyperloop model, while Maglevs are discouraged by Musk for being too expensive. Hence, by utilizing a firm that's been provided by the competition, we're using a cheaper hover engine, that provides levitation, thrust and braking in addition to the air bearing system that comes with the original design.
The air bearing, due to the constraints in the available tube diameter, will be situated around the guidance rail, thus providing attitude support during turns as well, asides allowing the pod to slide over the rail.
>>7628801
Lookin good m8
3. Chassis
The chassis will be mainly derived from commercially available Maglev structural designs, that have the following structural characteristicL:
>1) as light as possible,
>2) enough degrees of freedom,
>3) special mechanically-braking mode
>4) unique lateral load way
>5) vehicles fall on rail to slide under emergency
The chassis will be fitted with linear braking systems, pressurized air channels for the air bearings, and hover engines.
The track curve can determine the instantaneous position of the bogie, then the relative positions between bogies, bogie and second suspension system and car bodies by connection relationship and the absolute spatial positions of all parts, all of which only involve the deduction of geometric relationships.
>>7628857
t-thanks!
4. Compressors
This is the trickiest part at hand as our current team members don't have the expertise to provide a definite solution. Given how the reaction jets are supplied their air through the low pressure compressors on Harrier Rolls-Royce jet engine inlets, we have also proposed a high-bypass ratio compressor system (second one in the pic)
The idea is to have the initial compressor (the low pressure one) to have as large a diameter as possible, probably as large as the tube, to maximize the pressurized air that will both flow through the bypass (over the pod) and into the pod's compressor.
At this point I need to provide some further information: The air inside the tube will have an operating pressure of 100 Pa, which is about 1/1000th of atmospheric sea level pressure. There are certain couplings that arise from the boundary layers around the pod when reaching Mach speed, and also the allowable pressure that can enter the compressor. NASA analysts are suggesting we keep the operational speed around 0.6 Mach.
The competition tube is at a 1:2 ratio of the actual Hyperloop tube, which brings the outer diameter to around 6' / 1.82 m. Hence for our design it will not be very challenging to have compressor blades that are that large, however we will be required to stay unde rthe maximum mass limits of the competition.
Here are my questions:
1 - does the increased fan diameter allow for air to enter at a higher speed / lower pressure
2 - will this proposed system actually work, especially at transonic speeds
>>7628900
to add, there isn't a turbo engine in the hyperloop (no combustion), so the air is simply compressed twice and sent to air bearings
The entire power is supplied by Tesla Model-S batteries up front. The control systems are embedded, the communications will be handled through WiFi (1 mile test track)
Safety systems will be following the transportation standards in general. In tube breaches (atmospheric pressure air enters the low pressure tube) - the safety measures that are present in the Channel Tunnel (high pressure water flowing into atmospheric pressure tunnel) will be employed. In case of a breach inside the pod (high pressure air tries to leak into the tube), regular aircraft procedures and safety protocols will be employed.
Alright that's pretty much it! We're at the end of our concept design stage and we'll be preparing the Low-level design package until the end of December, assuming we'll pass this stage ofc.
What do you think /sci/?
pls respond
>>7628801
you guys pulled permits yet?
>>7629072
long way to go for that, gotta get accepted at the design competition first
Hello. How interesting, and well done. Since you started this I have occasionally pondered what the front of the train would look like. Looking at your 1st png, my heart dropped with the conventional appearance, then your compressor png brightened the outlook. Your team will have to combine some very differing elements from diverse tech to get that right, and good luck. Fwiw.
A) Japanese bullet trains have a distinct aero profile to maintain stability and wheel contactwhy reinvent the wheel.
B) The compressor needs a 'maw' to drag in enough air molecules at lower speeds to provide pressure - this maw will probably be large (as you state) equal to the CSA of the carriage.
C) The 2 requirements of A & B have to be married together somehow, and one way could be a front bogie (or sled) that is entirely aerodynamic cowl providing the initial stability for the compressor section (the maw of which would also be an interesting shape).
Function before form, it is going to look unusual.
>>7629129
thank you! actually we're going to change the design to pic related, perhaps it's more appealing
the front bogie/sled idea is very interesting, will consider it for sure
bump
Bump again
>>7629291
That is certainly how I envisaged the inlet cone, my thoughts were that the air bearings will work on tight tolerances, unlike a passenger jet engine, which is actually very flexible, this cannot be flexible, (and I 'feel' a fixed venturi will instill differing lateral forces at diff. velocities.) hence the requirement for an air-streamed bogie forward of this providing rigidity for the carriage (I am sure there are other solutions - like months of wind tunnel testing).
>>7629734
Got it, makes sense
bump
>>7628848
>>7629291
The primary challenge in building a working hyperloop is going to be the massive cost of the track, not the vehicle itself. This design is wasting half of the tube diameter, requiring a larger pipe be used that uses four times as much steel. On top of that, having to place the magnetic guide rail at the bottom and weld some sort of flat plate to each tube section is going to significantly raise labor costs a d probably prevent an automated track-assembler from being used.
It would be very prudent to find ways of making the track cheaper even if it meant making the vehicles significantly more expensive. There's only a few vehicles, but hundreds of miles of track.
>>7630410
I should've clarified better:
The guidance track and the plates at the bottom are provided by default to competitors by SpaceX. We're only expected to design the pod.
Pic related: tube spec drawing
>The test track will be an approximately 1-mile-long steel tube with a 6-foot outer diameter, fitted with an aluminum sub-track and rail mounted to a concrete fill bed. At the tube’s egress door, there is a 12-foot-long “foam pit” to help mitigate the {hopefully non-occurring} case of a Pod braking system failure. The tube sections will rest on concrete cradles, reinforced with steel and fitted with PTFE slip bearings.
>The parameters of the Hyperloop test track are:
>Material: ASTM A1018 Grade 36
>Outer diameter: 72.0 inches
>Inner diameter: 70.6 inches
>Wall thickness: 0.70 inches
>Length: 1 mile (approximate)
>Subtrack material: Aluminum 6101-T61
>Subtrack roughness: 125 RMS with potential for occasional surface scratches up to 0.008”
>Subtrack thickness: 1.0” for first and last 200 feet; 0.5” for remainder of tube
>Rail Material: Aluminum 6061-T6
>Internal Pressure: 0.02 – 14.7 PSI
>>7630710
forgot pic
bump
Bump
Pic related, we're going to put one of these bad boys to the front (only axial compressor minus the combustion chamber & turbine), covering about 85% of the entire tube cross-section, thus allowing our secondary compressor to work at transonic speeds
>>7628900
>air compressor
>that noise
also how heavy is your whole setup?
how much lift can the magnets provide?
what is the opening diameter of your compressor?
i.e. how much lift can it provide?
i get that all one has to do is to lift the whole assembly off in order to provide a frictionless surface, but even so, i doubt magnets alone in your design can provide enough lift.
additionally using an air assembly in a reduced pressure environment would produce reduced lift compared to using it in a normal air environment.
>>7630410
Crikey, what on earth makes you think the outer tube should be steel? Plastic, modular, it only needs to hold a vacuum and intermittent passing pressure from trains, it could probably be printed - dependant o the forces, even extruded.
>>7628900
You may encounter choking problems with increasing fan diameter as this will significantly increase the flow rate to the compressor (see choke lines on pic related).
Most transonic axial-flow compressors will not appreciate sonic flow over any of their components. Note that this is different to (and should not be confused with) locally supersonic flow on the blades themselves.
Again, this may or may not be an issue depending on the Mach number of your vehicle.
If it is you could consider a variably geometry intake and/or some kind of RAM compression system using oblique shocks instead.
>>7631944
>also how heavy is your whole setup?
we haven't done an exact assessment of the weights but you may assume it's around 1.5 tonnes
>how much lift can the magnets provide?
each hover engine has a payload of 48 kg, and they come in packs of 4 engines. Every bogie is fitted with these 4 engines, and there are 4 bogies, giving the maximum hover engine payload = 768 kg. In addition, the system will be fitted with air bearings, each having a carrying capacity of 217 kgs, paired and arrayed in 4, giving them a total capacity of 1736 kgs. The total levitation payload is around 2.5 tonnes.
>what is the opening diameter of your compressor?
>how much lift can it provide?
see above. the white paper proposes only air bearings for lift.
>>7632017
Obviously so, but SpaceX announced a steel tube
>>7632128
There's a NASA analysis that highlights the choke flow you've mentioned, with is coupled to the bypass flow around the pod. Pic related
>The Hyperloop passenger pod was decomposed into five analyses that were connected to form the conceptual sizing model.
>4. Tube Flow Limitations: Pod speed limitations based on choked flow restrictions.
>However, in order to achieve reasonable eciency from the compression system, the Mach number of the flow at the compressor face must be limited to less than about 0.65. For Mpod greater than 0.65, a diffuser must be added to the Hyperloop which will slow the air down before it enters the compressor.
The diffuser mentioned above is probably what you mean by variable geometries.
Basically NASA pulls down the top speed given down by SpaceX while doubling the tube size. Since the SpaceX tube dimension specs are not adhering to this change in diameter, we've thought about increasing the bypass pressure by adding an extra compressor, with a larger diameter, thus providing a high by-pass flow as seen in the pic here >>7628900
Question: should we scrap the additional compressor? If we should keep it, should we size it down instead?
>>7632367
>The total levitation payload
Capacity*
Bump
Sneaki Peaki
>>7628801
What the fucking fuck. Did you just make a maglev instead of a hyperloop? Did you do any cost analysis on this whatsoever? Fuck you aren't even allowed to modify the
Fuck, have you even answered some of the technical questions this hyperloop competition wants you to answer. IE what is the heat flux into the pod, safety mechanisms etc
this design is fucked, start over from first principles
>>7634567
>Did you just make a maglev instead of a hyperloop?
it's allowed, but this is a hover engine/air bearing combo not a maglev
from the tube spec:
>The test track has been designed to be flexible and to allow competitors to implement, at a minimum, the following three types of levitation/suspension:
>1. Wheels: The concrete (and aluminum) flat sections along the outside allow for a good wheel surface and aluminum rail(s) allow for horizontally oriented wheels, as implemented on certain roller coasters.
>2. Air Bearings: The aluminum plate allows for a much smoother and flatter surface than the steel tube itself. The rail(s) can be used for lateral control, either through side-mounted bearings or wheels.
>3. Magnetic levitation: Several forms of magnetic levitation require a conductive non-magnetic surface (e.g. copper or aluminum). The sub-track allows for magnetic levitation and the rail(s) allow for lateral control.
it's fine as long as it's not fully on wheels
>Did you do any cost analysis on this whatsoever
Arx Pax commercially available hover engines are $10k apiece, given 16 of them are there, with a special discount for hyperloop teams, should put the price tag to $100k, however reducing the number of air bearing skis by 70% - currently the offer from an air bearing firm
> Fuck you aren't even allowed to modify the
oh yes i am
>IE what is the heat flux into the pod
comes after the determination of compressors to be used, shouldn't sweat it given our tendency to stick to proven and available tech with lots of specs
>safety mechanisms
pretty much aircraft safeties for pod leaks, and deep water tunnel safeties for tube leaks will be proposed. same principles govern
>are you a youknowwho employee by any chance?
>>7634571
pls elaborate
>>7634567
oh btw, Arx Pax is endorsed by Hyperloop Competition Committee. In fact we've got to know them thanks to an email forwarded to group leads
How about, you hang the cars from the engine that has it's own tube
>>7634638
needs the compressor at the front to eliminate the piston effect
>>7634672
oh lol, i thought it was in a vacuum or something
>>7635030
it's near vacuum but not at complete vacuum, reduced pressure around 100 Pa. the reason is to mitigate damages that could be caused by possible leaks in the tube that would happen in a vacuum condition
bump
>>7628801
Those are some sexy designs.
>most of our members went away
I hope that you guys win the competition so the guys who left would feel really salty.
>>7638540
Thanks for your support m8, but it was rather unfortunate that the initial group broke up. We didn't have a single Aero guy on our team which stalled the design process and got people demotivated. It's natural, everyone's doing it voluntarily and this is an online group, so people drift apart easily.
Funny thing is, schools began and now we have more Aero guys than we ever needed.
If you from Sci-X are reading this, love you guys, best of luck in your affairs. Also you can get back anytime you like
>every time I read about the hyperloop I can't stop thinking about magtubes from SMAC
>>7639149
I've learned about a very interesting thing about technology history when reading into tubes. Apparently, pneumatic tubes were a thing in 1800s where people pumped their mails back and forth, to create a pseudo-internet back in the day. People were BLOWN AWAY by this, there are articles in newspapers speaking about how "the future will be pneumatic", raving about the tubes how we do about the internet. Then phones and cargo trucks came, and pneumatic tubes became a thing of the past.
pic related - a pneumatic mail container
here's a smithsonian article about it
http://www.smithsonianmag.com/innovation/hyperloop-latest-innovation-pretty-much-series-of-tubes-180955735/?no-ist
>>7639906
last i checked, they still have them at bank drive through
>>7641658
thanks for the friendly bump m8
have a compressor render
guys btw
anyone have any idea where we can order turbofans + compressors without the combustion engine?
the business is completely build on a b2b model which is logical, but we have electrical motors to get the fans and compressors working
currently spamming emails to suppliers but i'm not even sure if that would be helpful
>>7639906
The atm at the bank in the town where I grew up (Massachusetts in the 90s) was one of these tube machines which just carried your checks/money/paper/documents/etc back and forth from a real person and a drivethru in the parking lot.
I always thought it was so cool. Haven't seen one on the west coast since I moved out here (2011?)
>>7641956
>A
>FUCKING
>JET ENGINE
the tube will melt you fucking nigger
>>7628848
what is the composition and grain structure of astm a1018 grade 36? can't be bothered to look it up.
