Congratulations to Tesla meeting the Model 3 production target. Elon pulled out all the stops even working the production line himself. The reason I bring this up is maybe, just maybe, the “Elon time” curse may be abating.There has been lots of negativity discussing Elon schedules pertaining to SpaceX and BFR. Let us give him credit when credit is due.
I hope he didn't burn himself out in the process.Quote from: testguy on 07/02/2018 01:19 amCongratulations to Tesla meeting the Model 3 production target. Elon pulled out all the stops even working the production line himself. The reason I bring this up is maybe, just maybe, the “Elon time” curse may be abating.There has been lots of negativity discussing Elon schedules pertaining to SpaceX and BFR. Let us give him credit when credit is due.
I would strongly suggest we stay away from that topic considering the many eyes on here.
How many tanker flights would be needed for BFS to do a circumlunar mission?
Quote from: Negan on 07/03/2018 03:23 pmHow many tanker flights would be needed for BFS to do a circumlunar mission?Possibly none, for sufficiently small payload, probably around 5 tonnes.With a single refueling flight, it could put 40 tonnes of payload though TLI and land it back on Earth with a free return.
A refilled vehicle in LEO can get around 20 tons landed on the surface and back to the surface of earth.
Quote from: speedevil on 07/03/2018 03:38 pmA refilled vehicle in LEO can get around 20 tons landed on the surface and back to the surface of earth.Thia scenario has always interested me when it comes to their testing. You know they will do a full tanker fill up as a test so might as well use it for this too.
Quote from: Negan on 07/03/2018 04:15 pmQuote from: speedevil on 07/03/2018 03:38 pmA refilled vehicle in LEO can get around 20 tons landed on the surface and back to the surface of earth.Thia scenario has always interested me when it comes to their testing. You know they will do a full tanker fill up as a test so might as well use it for this too.There are reasonable concerns and arguments why landing on the moon might entail risks.Apollo largely sidetepped them due to leaving the descent stage on the ground.Landing a vehicle with 350 ton thrust at landing that the engines have to work again is perhaps not risk free.There are other reasonable strategies that make it much less risky to do stuff on the moon, for example, descent and hovering while translating slowly at 50m while spending 30s throwing stuff out the airlock and then going home.A 'hard landing' with airbags at 30mph is very survivable indeed for Tesla vehicle sized payloads.Light modifications get you to something controllable for a week to do really deep surveying and surface modification of the landing area, for next time.
Quote from: speedevil on 07/04/2018 09:46 amThere are other reasonable strategies that make it much less risky to do stuff on the moon, for example, descent and hovering while translating slowly at 50m while spending 30s throwing stuff out the airlock and then going home.There might be issues with even getting near the surface. Exhaust gas velocities are well above orbital speeds so a landing anywhere will contaminate the entire moon with fast dust particles.
There are other reasonable strategies that make it much less risky to do stuff on the moon, for example, descent and hovering while translating slowly at 50m while spending 30s throwing stuff out the airlock and then going home.
From what I understand, BFS (Big Falcon Spaceship) will be built first and tested. It will be a SSTO vehicle with very little payload. For missions to and from the moon, it would require the BFR (Big Falcon Rocket) first stage booster to be built to lift the BFS. That is unless the BFS can be refueled in LEO with tankers or a fuel depot. BFS requires far more development and testing. They have already landed a first stage with F9. So building a BFR would be much easier. So unless you guys are talking about refueling a test BFS in LEO to do a moon mission test. It would have to be refueled with a FH or multiple F9 vehicles.
*Note: For calibration, the BFS is approximately the size and double wet mass of the SLS core stage with approaching double the propulsive thrust. This is a B-I-G F'n Spaceship.https://www.nasa.gov/sites/default/files/thumbnails/image/core_stage_infographic_reboot.jpg