BFR early next year.

In article ,
says...

On 2018-03-12 20:37, Alain Fournier wrote:

Elon Musk said at South by Southwest that his Big Falcon Rocket
would start doing small test flights early next year.


"small test" ? a 1m high scale model with a tank of diet coke into which
a Mentos candy is dropped? :-)


Space-X apparently has begun to test its new Raptor engines.

For commercial aircraft, they can mount a new engine on a 747 and test
it in flight. (same fuel, and sufficiently spaced pylons make it
possible to mount new engine)


What are Musk's options to test fly the new engines?

BFS. It could be that the first BFS would be similar to Grasshopper or
Enterprise in that it won't have all the systems necessary for
supporting a crew in space. Automated testing only.

Can they built a Falcon-9 with a few raptor engines and a methane tank
instead of Kerosene for a test flight?

No, not without significant engineering, which would be a complete waste
of time and money.

Or must one assume that a test flight will be raptor engines on a BFR
stage 1 (even if it is topped by a cone instead of stage 2) ?

I believe BFS will be tested first. It has fewer engines than BFR.
Also, it might even have SSTO capability by itself without much payload
of course.

From a light load point of view, is it a problem of the methane and LOX
tanks are only partly fueled since this is such a short flight? or would
this require smaller tanks?

You can do a partial fill for short "hops". Does your car's gas tank
need to be full to make a trip to the grocery store?

Or can the tank be fitted with a helium
filled balloon that fill's the otherwise empty tank space?

WTF? Nope, nope, nope.

Jeff
--
All opinions posted by me on Usenet News are mine, and mine alone.
These posts do not reflect the opinions of my family, friends,
employer, or any organization that I am a member of.

On 18-03-13 11:53 , Jeff Findley wrote:
In article ,
says...

On 2018-03-12 20:37, Alain Fournier wrote:

Elon Musk said at South by Southwest that his Big Falcon Rocket
would start doing small test flights early next year.
...
Or must one assume that a test flight will be raptor engines on a BFR
stage 1 (even if it is topped by a cone instead of stage 2) ?

I believe BFS will be tested first. It has fewer engines than BFR.

For small, Grasshopper-like hops, it would be enough to mount just one
of the two (or are there now more than two?) BFS sea-level engines.

From a light load point of view, is it a problem of the methane and LOX
tanks are only partly fueled since this is such a short flight? or would
this require smaller tanks?

You can do a partial fill for short "hops". Does your car's gas tank
need to be full to make a trip to the grocery store?

The BFS has the smaller "header tanks" (inside the main fuel tank). If
only these tanks are used in the hops, the unused volume is not so large.

--
Niklas Holsti
Tidorum Ltd
niklas holsti tidorum fi
. @ .

In article ,
lid says...

On 18-03-13 11:53 , Jeff Findley wrote:
In article ,
says...

On 2018-03-12 20:37, Alain Fournier wrote:

Elon Musk said at South by Southwest that his Big Falcon Rocket
would start doing small test flights early next year.
...
Or must one assume that a test flight will be raptor engines on a BFR
stage 1 (even if it is topped by a cone instead of stage 2) ?

I believe BFS will be tested first. It has fewer engines than BFR.

For small, Grasshopper-like hops, it would be enough to mount just one
of the two (or are there now more than two?) BFS sea-level engines.

Agreed. Two, from this pictu

https://ourplnt.com/wp-content/uploa...-1024x1024.jpg

From a light load point of view, is it a problem of the methane and LOX
tanks are only partly fueled since this is such a short flight? or would
this require smaller tanks?

You can do a partial fill for short "hops". Does your car's gas tank
need to be full to make a trip to the grocery store?

The BFS has the smaller "header tanks" (inside the main fuel tank). If
only these tanks are used in the hops, the unused volume is not so large.

Yep, that's what it shows in the picture.

Jeff
--
All opinions posted by me on Usenet News are mine, and mine alone.
These posts do not reflect the opinions of my family, friends,
employer, or any organization that I am a member of.

On 18-03-14 00:36 , Jeff Findley wrote:
In article ,
lid says...
...
For small, Grasshopper-like hops, it would be enough to mount just one
of the two (or are there now more than two?) BFS sea-level engines.

Agreed. Two, from this pictu

On the other hand, at
https://www.teslarati.com/elon-musks...bfs-spaceship/,
Musk is quoted as follows (in the section headed "Raptor and rocket
propulsion"):

"If you just have two engines that do everything, the engine complexity
is much higher and, if one fails, you’ve lost half your power. Btw, we
modified the BFS design since IAC to add a third medium area ratio
Raptor engine partly for that reason (lose only 1/3 thrust in engine
out) and allow landings with higher payload mass for the Earth to Earth
transport function."

(Gosh, perhaps the "Earth to Earth transport function" is to be taken
seriously...)

--
Niklas Holsti
Tidorum Ltd
niklas holsti tidorum fi
. @ .

In article ,
lid says...

On 18-03-14 00:36 , Jeff Findley wrote:
In article ,
lid says...
...
For small, Grasshopper-like hops, it would be enough to mount just one
of the two (or are there now more than two?) BFS sea-level engines.

Agreed. Two, from this pictu

On the other hand, at
https://www.teslarati.com/elon-musks...bfs-spaceship/,
Musk is quoted as follows (in the section headed "Raptor and rocket
propulsion"):

"If you just have two engines that do everything, the engine complexity
is much higher and, if one fails, you?ve lost half your power. Btw, we
modified the BFS design since IAC to add a third medium area ratio
Raptor engine partly for that reason (lose only 1/3 thrust in engine
out) and allow landings with higher payload mass for the Earth to Earth
transport function."

(Gosh, perhaps the "Earth to Earth transport function" is to be taken
seriously...)

This is all very fluid right now, isn't it?

Jeff
--
All opinions posted by me on Usenet News are mine, and mine alone.
These posts do not reflect the opinions of my family, friends,
employer, or any organization that I am a member of.

On 3/14/2018 6:24 AM, Jeff Findley wrote:
In article ,
lid says...

(Gosh, perhaps the "Earth to Earth transport function" is to be taken
seriously...)

This is all very fluid right now, isn't it?

Jeff


Yes, but I would also take P2P transport very seriously. I suspect Elon is.

Dave

Niklas Holsti wrote on Wed, 14 Mar
2018 09:22:15 +0200:

On 18-03-14 00:36 , Jeff Findley wrote:
In article ,
lid says...
...
For small, Grasshopper-like hops, it would be enough to mount just one
of the two (or are there now more than two?) BFS sea-level engines.

Agreed. Two, from this pictu

On the other hand, at
https://www.teslarati.com/elon-musks...bfs-spaceship/,
Musk is quoted as follows (in the section headed "Raptor and rocket
propulsion"):

"If you just have two engines that do everything, the engine complexity
is much higher and, if one fails, you’ve lost half your power. Btw, we
modified the BFS design since IAC to add a third medium area ratio
Raptor engine partly for that reason (lose only 1/3 thrust in engine
out) and allow landings with higher payload mass for the Earth to Earth
transport function."

(Gosh, perhaps the "Earth to Earth transport function" is to be taken
seriously...)


Yeah, I thought all the later drawings and such that I'd seen showed 3
atmospheric engines vice 2. I believe it can still land on a single
engine, though.


--
"The reasonable man adapts himself to the world; the unreasonable
man persists in trying to adapt the world to himself. Therefore,
all progress depends on the unreasonable man."
--George Bernard Shaw

On Mar/13/2018 at 5:53 AM, Jeff Findley wrote :
In article ,
says...

On 2018-03-12 20:37, Alain Fournier wrote:

Elon Musk said at South by Southwest that his Big Falcon Rocket
would start doing small test flights early next year.


"small test" ? a 1m high scale model with a tank of diet coke into which
a Mentos candy is dropped? :-)


Space-X apparently has begun to test its new Raptor engines.

For commercial aircraft, they can mount a new engine on a 747 and test
it in flight. (same fuel, and sufficiently spaced pylons make it
possible to mount new engine)


What are Musk's options to test fly the new engines?

BFS. It could be that the first BFS would be similar to Grasshopper or
Enterprise in that it won't have all the systems necessary for
supporting a crew in space. Automated testing only.

In
https://www.theregister.co.uk/2018/0...xsw_interview/
it isn't quite clear whether the test if for BFR or BFS. But I'm not
sure if you are stating as fact that it will be BFS or if that is
just your guess. So do you know that it will be BFS or do you think
it will be BFS.

Can they built a Falcon-9 with a few raptor engines and a methane tank
instead of Kerosene for a test flight?

No, not without significant engineering, which would be a complete waste
of time and money.

Or must one assume that a test flight will be raptor engines on a BFR
stage 1 (even if it is topped by a cone instead of stage 2) ?

I believe BFS will be tested first. It has fewer engines than BFR.
Also, it might even have SSTO capability by itself without much payload
of course.

I would be very surprised if BFS had anything close to SSTO capability.
It is a spaceship not a launch vehicle.


If they do just a little hop with BFR or BFS, I would call that just
a small test. But I'm not if it should be called a small ****ing test
or what :-)


Alain Fournier

On 18-03-13 23:01 , Alain Fournier wrote:
...
I would be very surprised if BFS had anything close to SSTO capability.
It is a spaceship not a launch vehicle.

Musk has said the BFS can do SSTO. Quotes from Musk's answer at
https://www.teslarati.com/elon-musks...bfs-spaceship/,
section headed "DEVELOPMENT SCHEDULE":

--- start quote:

Q: ... Will we see BFS hops or smaller test vehicles similar to
Grasshopper/F9R-Dev? Facilities being built? Propellant plant testing?
etc. etc.

A (Elon): Will be starting with a full-scale Ship doing short hops of a
few hundred kilometers altitude and lateral distance. Those are fairly
easy on the vehicle, as no heat shield is needed, we can have a large
amount of reserve propellant and don’t need the high area ratio, deep
space Raptor engines.

Next step will be doing orbital velocity Ship flights, which will need
all of the above. Worth noting that BFS is capable of reaching orbit by
itself with low payload, but having the BF Booster increases payload by
more than an order of magnitude. Earth is the wrong planet for single
stage to orbit. No problemo on Mars.

--- end quote.


--
Niklas Holsti
Tidorum Ltd
niklas holsti tidorum fi
. @ .

On Mar/13/2018 at 6:09 PM, Niklas Holsti wrote :
On 18-03-13 23:01 , Alain Fournier wrote:
Â*Â* ...
I would be very surprised if BFS had anything close to SSTO capability.
It is a spaceship not a launch vehicle.

Musk has said the BFS can do SSTO. Quotes from Musk's answer at
https://www.teslarati.com/elon-musks...bfs-spaceship/,
section headed "DEVELOPMENT SCHEDULE":

--- start quote:

Q: ... Will we see BFS hops or smaller test vehicles similar to
Grasshopper/F9R-Dev? Facilities being built? Propellant plant testing?
etc. etc.

A (Elon): Will be starting with a full-scale Ship doing short hops of a
few hundred kilometers altitude and lateral distance. Those are fairly
easy on the vehicle, as no heat shield is needed, we can have a large
amount of reserve propellant and don’t need the high area ratio, deep
space Raptor engines.

Next step will be doing orbital velocity Ship flights, which will need
all of the above. Worth noting that BFS is capable of reaching orbit by
itself with low payload, but having the BF Booster increases payload by
more than an order of magnitude. Earth is the wrong planet for single
stage to orbit. No problemo on Mars.

--- end quote.

Thanks for that. The web page you cited is very interesting.


Alain Fournier