### Author Topic: Spacex BFR seating?  (Read 1184 times)

#### Tanner_Witton

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##### Spacex BFR seating?
« on: 04/07/2018 12:06 AM »
Hey guys,

Just heard about Spacex launching some "hopper flights" with their new BFR. That made me wonder, how many passengers can the BFR carry? The old 2016 design was able to carry 100 passengers to Mars, I'm not exactly sure how much this one can carry.

BFR:

Here are some questions I have about the BFR's passenger seating.

Let's assume that all passengers are 150-300lbs (because of spacesuits). BFR spaceships start with full fuel.

1)   How many passengers can the BFR carry to the ISS?

(I'm going to assume about maximum 80 passengers)

2)   How many passengers can the BFR carry to the Mars?

(Elon Musk said that the BFR can also carry passengers to Mars. I think that 10-20 people can go to mars on the BFR. The rest of the payload includes food, water, entertainment and other supplies.)

3)   How many passengers can the BFR carry to the lunar surface and back?

(Trips to the lunar surface will certainly be very complex since most of your fuel has been used up escaping earth's orbit and landing. I think that only 3 - 5 people can land on the moon and return riding the BFR.)

4)   How many passengers can the BFR carry trips around the earth?

(The BFR can probably carry 80 passengers around the earth just like the ISS. The new BFR is smaller than the 2016 BFR. Trips around the world are only 30mins to an hour so not much food or other supplies will be needed in the process.)

So, what do you guys think?

#### Bob Shaw

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##### Re: Spacex BFR seating?
« Reply #1 on: 04/07/2018 12:22 AM »
I think that seating is going to be defined by life support. Open vs regenerative suggests that all initial crews will be small, and seating won't be an issue. Also, forget all those windows!

#### speedevil

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##### Re: Spacex BFR seating?
« Reply #2 on: 04/07/2018 01:32 AM »
I think that seating is going to be defined by life support. Open vs regenerative suggests that all initial crews will be small, and seating won't be an issue. Also, forget all those windows!

For short trips, it's basically irrelevant.
Half an hour and it's really hard to pack people densely enough that it gets more than stuffy, with absolutely no life support.

15 litres a minute of air, from a once-through mask, simply vented overboard, comes to around 1.5kg/hr/passenger, from liquid oxygen/nitrogen.
Up to a day or so, that's really quite plausible with minimal impact.

This is implied by the price of fuel and 'cheaper than economy' - you can't do that at all with fifty passengers.

Lunar surface is more constrained. With a lunar depot (another BFS), and a full BFS in earth orbit, a hundred tons or so is managable, so in principle several hundred people.

Twenty tons if no depot. , which even if you assume completely open-loop life support gets you considerably more than ten people.

Paying very minor attention to life support drops the amount of air needed from 500kg per person-fortnight to 100kg or so (low pressure oxygen, some nitrogen, carbon dioxide scrubbing.

Mars is rather different - you need to do it 'properly'.

You may want to re-watch the video at the start of the thread, several of these questions are answered.

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