### Author Topic: How will the seats be positioned in the BFS?  (Read 1257 times)

#### Steve D

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##### How will the seats be positioned in the BFS?
« on: 01/09/2018 08:43 PM »
Was wondering about this the other day. Liftoff and landing the acceleration would be vertical so a reclining seat should work fine. However during reentry the forces will be sideways until the ship flips for landing. Will the seats have to reorient themselves during the flip?
Steve
« Last Edit: 01/09/2018 08:43 PM by Steve D »

#### speedevil

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##### Re: How will the seats be positioned in the BFS?
« Reply #1 on: 01/09/2018 09:45 PM »
Was wondering about this the other day. Liftoff and landing the acceleration would be vertical so a reclining seat should work fine. However during reentry the forces will be sideways until the ship flips for landing. Will the seats have to reorient themselves during the flip?
Steve

The forces are going to be quite complex and varying vectors throughout entry.
- 35:32 is the simulation for mars entry.
The initial part is misleading as it's curving the trajectory from a hyperbolic orbit into Mars, and the rest is misleading as earth gravity is 1G, not 1/3.

Beds are also a plausible option - with the bed oriented around the axis that it can spin so down always is consistent.

Can someone perform an accurate integrated CFD/kinetic simulation of the apparent shape of the BFS and compute the accurate reentry profile - so we can argue about seating?

Some of the design of the BFS-P2P shown is very aspirational, and reminiscent of 'sky lounges' from the 70s in 747s.

These went away quite quickly indeed to bring up passenger numbers.
Sketches I've done of possible passenger configs vary enormously.

- from four or so passengers in thirty of these cabins with a crewmember per cabin, and a 'zero G experience' flight where you get to go up and look through the massive windows and have a play for a bit well supervised.

To 1500 or so passengers on lightweight rotating cots on tightly spaced floors for a twenty five minute flight. Passengers may get a occulus rift to look outside, or use the free wifi with their tablet.

A mix is of course another possibility.

How you get people on/off is another major issue. Do the cabins shown actually move on circumferential and tangential rails - if they do, they can load in and out already packed and with the passengers somewhat comfortable in them.

Or do people have to walk on and find their seats/couches.
The latter takes more time at high seating densities with fewer staff.

And of course - what emergency evacuation is legislatively required could kill this.

If the FAA takes a stance for mass transit that all passengers must be able to be evacuated in ten seconds at up to max-Q - oh dear.

I can't think of even trivial crashes going survivably and making evacuation very meaningful.
Perhaps off fixture landing.
But can BFS even survive falling over from zero speed at landing without a massive explosion?
« Last Edit: 01/09/2018 09:54 PM by speedevil »

#### nacnud

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##### Re: How will the seats be positioned in the BFS?
« Reply #2 on: 01/09/2018 09:53 PM »
There were these speculative images posted to imgur. Something for the imagination to work with.

#### speedevil

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##### Re: How will the seats be positioned in the BFS?
« Reply #3 on: 01/09/2018 10:05 PM »
There were these speculative images posted to imgur. Something for the imagination to work with.

Clearly Mars transport for 2016 version.

The drawn images fit 102 people in 4 layers in 4.4m of hull height.
At that density, you can fit perhaps 300 people, with more layers and no cargo.
The capsules - especially the hatches - are notably more cramped in the ~8.8m internal diameter than the ~11.8m.
https://i.imgur.com/XfIQhizl.jpg - from the above.

#### oiorionsbelt

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##### Re: How will the seats be positioned in the BFS?
« Reply #4 on: 01/10/2018 05:42 PM »
Perhaps the seating for the more dynamic aspects of flight will be rapidly rotating, like HMXHMX's t/Space CXV seats.

Page 5 of the pdf

#### Ionmars

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##### Re: How will the seats be positioned in the BFS?
« Reply #5 on: 01/11/2018 08:14 PM »
There were these speculative images posted to imgur. Something for the imagination to work with.

Clearly Mars transport for 2016 version.

The drawn images fit 102 people in 4 layers in 4.4m of hull height.
At that density, you can fit perhaps 300 people, with more layers and no cargo.
The capsules - especially the hatches - are notably more cramped in the ~8.8m internal diameter than the ~11.8m.
https://i.imgur.com/XfIQhizl.jpg - from the above.
I have been allowing 7.8 m average internal diameter (0.6 m walls) for shell , stringers, and multilayer insulation. Your 8.8 m figure is much more attractive. Do you have a reference? Thanks
* Mars' orbit: a convenient service station for an asteroid-sized spaceship en-route to Ceres. *

#### speedevil

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##### Re: How will the seats be positioned in the BFS?
« Reply #6 on: 01/12/2018 06:22 AM »
I have been allowing 7.8 m average internal diameter (0.6 m walls) for shell , stringers, and multilayer insulation. Your 8.8 m figure is much more attractive. Do you have a reference? Thanks

Shell, stringers and insulation can overlap somewhat in depth - the structure coming into the passenger cabin past the insulation may even be an option.
To do thermal control from the heat/cold of space needs a few centimetres of good insulation - assuming barbecue roll, something in orbit over the night-side of earth only gets to -40C or so, which can be dealt with with 10cm thick vacuum insulated panels and get heat outflow of 150W/m^2, which is managable with very small heaters for half an hour.

(of the same order as a tesla pack to heat the entire BFS).

The insulation may need to be a little thicker over the heatsheild, but can't be very much so as you can't have the internal insulation allowing the shell to warm up too much or there are issues.

10cm is probably a not insane number for the very outer edge of the habitable volume with some parts of the structure extruding through this.

This is for P2P service.
If you've got the thing pointed at the sun, or with the engines pointed at the sun and are coasting towards Mars without a hot earth nearby, you're going to need to put more thought into thermal design.

#### Ionmars

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##### Re: How will the seats be positioned in the BFS?
« Reply #7 on: 01/12/2018 01:23 PM »
Thanks for your insight. So a p2p flight could employ less insulation, as compared to an inter-planetary flight.
* Mars' orbit: a convenient service station for an asteroid-sized spaceship en-route to Ceres. *

#### Ionmars

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##### Re: How will the seats be positioned in the BFS?
« Reply #8 on: 01/12/2018 01:34 PM »
Back on topic I found this in the pdf suggested by Orionsbelt above:

"The CXV crew sits facing forward during ascent to space, but must face aft during entry to better
withstand high-g deceleration forces. The innovative crew seat has the ability to rapidly rotate
180 degrees for entry or in the case of an abort. The seat, which is installed in the mockup, has
other unique features:
- 􀀹􀀹 Very low mass, weighing less than 10% of the Space Shuttle crew seat
- 􀀹 Straps sewn to attenuate loads if the design limit of 8 g is exceeded.
- 􀀹 Provides rapid re-orientation with no electrical power required.
A pull of the rotation handle releases the seat latch and a torsion spring rotates the seat 180
degrees where it is locked in place.
The seat was developed under a t/Space grant to the
Auburn University College of Engineering, under the direction of former astronautJim Voss.
Voss, who is now t/Space Vice President for Space Exploration Systems, led ateam that included
one graduate research assistant and twelve aerospace engineering seniors.
Applying the t/Space rapid prototyping philosophy, they moved from concept to fully functional
prototype in three months.The effort produced a functional prototype that met all requirements: t/Space Requirements
Prototype Performance:
Weigh less than 20% of Space Shuttle seat 12 lbs (Less than 10% of Shuttle seat)
180 degree rotation within 3 seconds 180 degrees in less than 2 seconds