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The control surfaces of BFS will be nearly perpendicular to slipstream for a majority of EDL, though.


Yeah, but with a different choice of technology, they might not have to be.

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Has ionized atmospheric plasma flow of EDL been tested with plasma-augmented control surfaces?

No idea - has anybody ever attempted this "brakeron" stuff before for EDL? I thought all of this breaking new ground anyway.
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Space Science Coverage / Re: Proposed Europa Missions
« Last post by Star One on Today at 08:21 AM »
How did this topic morph into a discussion of the Federalist Papers? With a side order of snark in both directions?

I am glad it morphed back. Let's try to keep it that way, thanks.
A number of posts have disappeared.  ???

I expect possibly for the reason I posted above.
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Maybe this is ignorant - but what about ElectroAerodynamics (aka. Plasma Aerodynamics) - ie. the use of electrified surfaces to generate plasma to selectively alter the flow around the vehicle for control purposes?

https://en.wikipedia.org/wiki/Plasma_actuator#Supersonic_and_Hypersonic_flow_control

http://www.pbs.org/wgbh/nova/next/space/plasma-air-control/



Technically, the entire surface of the vehicle would be available for such usage. Even though ElectroAerodynamics doesn't have offer the same amount of control authority per unit area, the fact that you could use all available surfaces to do it might make up for that.

And since this technology is solid-state, you don't have to worry about reliability or speed issues, as with mechanical actuators.

The control surfaces of BFS will be nearly perpendicular to slipstream for a majority of EDL, though. 

Has ionized atmospheric plasma flow of EDL been tested with plasma-augmented control surfaces?   
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SpaceX BFR - Earth to Deep Space / Re: BFR GTO capability
« Last post by hkultala on Today at 07:59 AM »
Yeah, of course it can do a 2nd burn. The real question is does it need orbital refueling before it does GTO burn. The 2017 version doesn't, but with the lower Isp engine and potentially higher dry mass, not sure if the 2018 version can still do single launch GTO mission.

If the craft weights about 90 tonnes and can lift 110 tonnes to LEO, it means i could lift a 8-tonne satellite plus 102 tonnes of fuel to orbit.

Unfortunately it does not have extra tanks for this fuel and it it wants to have this fuel available in main tanks, it has to leave this fuel unused in the main tanks, burning less than "optimal for maximum payload" for the main burn to LEO, meaning the mass to LEO drops a bit.

This means that in practice, without extra tanks, with the 8-tonne satellite, it could lift slightly smaller amount of fuel to LEO, maybe like 90 tonnes.

LEO to GTO is about 2.5km/s.

90+90+8 = 188 tonnes initial mass, 98 tonnes final mass, 357 second specific impulse gives about 2.28 km/s delta-v after LEO.

So, GTO not achievable with these numbers with 8-tonne satellite.

But, if the satellite launcher version of BFS is only 80 tonnes instead of 90 tonnes, and it can lift slightly more to LEO (100 tonnes of fuel + 8-tonne satellite), then we get about 2.65 km/s delta-v after LEO, enough for GTO.

So, close call. I think they are nailing the details in such way that it will work for the biggest common GTO satellites, as GTO satellites are important source of income.




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Cosmic Penguin: In the press conference for @haya2e_jaxa it has just been mentioned that the 2 MINERVA-II probes are thought to have successfully touched down, as their voltages dropped at the exact moment they should enter the shadow if they are on Ryugu's surface!

https://twitter.com/Cosmic_Penguin/status/1043043105795006464
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...because the cost to construct each vehicle will (at least initially) make it more expensive than any other vehicle on the market...
Depending on timing, I'd venture that an expendable BFS may be cheaper than a Delta IV Heavy

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... If using up a F9 flight costs you less, then ...
Given that there is talk of F9/H reentry tests, not a reusable S2, if an F9 or FH flight costs less than a BFS flight due to the amortization then BFR/BFS has failed to meet a large portion of its goals.

 Let's not put the cart before the horse, though.  FH has flown once.  Looking forward to the next flight....
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Maybe this is ignorant - but what about ElectroAerodynamics (aka. Plasma Aerodynamics) - ie. the use of electrified surfaces to generate plasma to selectively alter the flow around the vehicle for control purposes?

https://en.wikipedia.org/wiki/Plasma_actuator#Supersonic_and_Hypersonic_flow_control

http://www.pbs.org/wgbh/nova/next/space/plasma-air-control/



Technically, the entire surface of the vehicle would be available for such usage. Even though ElectroAerodynamics doesn't have offer the same amount of control authority per unit area, the fact that you could use all available surfaces to do it might make up for that.

And since this technology is solid-state, you don't have to worry about reliability or speed issues, as with mechanical actuators.
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I believe that there was a very small manoeuvre on May 23 when the orbital period increased from 90.682 minutes to 90.695 minutes.
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So far the Cosmos 2525 orbit has continued its slow decay.
Maybe it's a satellite without an engine ?
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