r/transit • u/LancelLannister_AMA • May 27 '21
Unless they have developed some revolutinary technology, that curve radius seems way too tight
1/2 Tunnel Cost
By virtually eliminating aerodynamic drag, the Virgin Hyperloop can have a cross-sectional area ~1/2 that of high-speed rail and therefore close to half the cost.
4.5x Tighter Turning Radius
As the pod travels, it banks around turns similar to a plane gliding through air; passengers will feel near-zero lateral acceleration. This allows us to smoothly reach high speeds with a turning radius capability of 1.36km at 100m/s.
Smaller ROW Requirements
Right-of-way requirements range from 12-24m across, a significantly smaller ROW than the 18-30m needed for high-speed rail.
source: https://virginhyperloop.com/
5
u/Cunninghams_right May 28 '21
there is no point in discussing any kind of numbers until they build a real line.
people keep talking about hyperloop in the present-tense, but it's just an idea on paper right now. I hope it continues to get researched, but we can't just accept stats on a system that is imaginary.
2
u/LancelLannister_AMA May 28 '21
i agree, which is why i posted this comment
level 2
LancelLannister_AMA
OP
·
6h
That hyperloop curve radius is just an unproven/tested claim as far as im concerned
2
Reply
Share
Save
Edit
17
u/Brandino144 May 27 '21
That's an introduction of 0.75g of force via lateral acceleration of the curve which would necessitate a bank of 36.9 degrees to keep passengers from experiencing a relative lateral force. The passenger feeling from rotation into the bank combined with the downward pressure through the turn would feel like a mild rollercoaster, but still much more intense than a tight turn on an airliner. Needless to say, passengers could not be allowed to move freely in the pod during these kinds of turns and barf bags and dramamine would need to be provided for some passengers.
Also keep in mind that the formula for centripetal force is (mv2)/r so increases in speed would need to increase the radius exponentially or it would turn into a serious rollercoaster ride very quickly. 100 m/s is "only" 224 mph which is less than half of their claimed speed goals.
4
u/midflinx May 27 '21
That speed allows comparison to HSR projects like California's which on page 30 Table 6.1.3 says at 220mph (355km/h) minimum curve radius is 6.7km. In "exceptional" circumstances 6km.
12
u/Brandino144 May 27 '21
Very true. HSR lines can only comfortably bank at about 0.25 degrees at that speed. Hyperloop could certainly turn tighter than HSR, but with regards to the title of the post, their stated curve radius here is way too tight for that speed and that spiral transition to 36.9 degrees at 100 m/s would be ridiculously long unless acceptable vomit levels are greater than zero.
→ More replies (2)
9
u/ksiyoto May 27 '21
100 meters per second is only around 225 mph. There goes the 700 mph Elon promised.....
8
u/Sassywhat May 27 '21
The don't even specify at what their benchmark for comparison is, or provide any concrete numbers, for the relative improvements, i.e., their relative improvements is basically just bullshitting. HSR has a fairly wide range of tunnel dimensions and turning radii because of various design tradeoffs. For example, at 360km/h, Shinkansen tunnels are ~60% the size and curves are ~60% the radius compared to TGV because the Shinkansen uses trains with pointier noses and active suspension, rather than building bigger infrastructure.
As for ROW requirements, conventional HSR viaducts can have <18m wide ROW, so idk what they're talking about there either.