Successful SpaceX launch

I watched the Falcon 9/Dragon launch live and it looked successful.
This Dragon is carrying BEAM to ISS, which is a first.

Also, and likely the most historic, the first stage landed successfully
on the barge, which is a first!

Congrats to SpaceX! Here is hoping that they inspect and re-launch that
recovered first stage, which would be another first (re-launch of a
liquid fueled first stage recovered from an orbital launch).


Oh yea, cite:

http://www.theverge.com/2016/4/8/113...uccess-falcon-
9-rocket-barge-at-sea

Why is this important? Because (from the above article):

The Falcon 9 costs $60 million to make and only $200,000 to fuel.

I'm tired of people saying "chemical propulsion is too expensive" when
the fuel is so damn cheap! Fuel costs are *not* the problem.
Skylon/Sabre is a solution to a problem which *does not exist*!

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.

Jeff Findley wrote:
Also, and likely the most historic, the first stage landed successfully
on the barge, which is a first!

I managed to get online to see the youtube-carried technical feed.
How long does the stage just sit there bobbing in the ocean with the
barge waiting for a rogueish wave to come along and upset the apple
cart?

rick
--
web2.0 n, the dot.com reunion tour...
these opinions are mine, all mine; HPE might not want them anyway...
feel free to post, OR email to rick.jones2 in hpe.com but NOT BOTH...

In article , says...

Jeff Findley wrote:
Also, and likely the most historic, the first stage landed successfully
on the barge, which is a first!

I managed to get online to see the youtube-carried technical feed.
How long does the stage just sit there bobbing in the ocean with the
barge waiting for a rogueish wave to come along and upset the apple
cart?

Not sure, but the barge is stabilized by thrusters at its corners. The
stage also has to be made "safe". For example, any remaining LOX must
be removed, likely by allowing it to boil off and vent. I'm sure there
are other things which need to be done before people can come near the
stage.

The plan is then (as far as I know it) is for welders to board the barge
and weld "shoes" over the "feet" of legs on the first stage to hold it
firmly in position until the barge can make it back to shore. Hopefully
that goes according to plan.

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.

When I studied rocket propulsion at the Ohio State University, under Garvin vonEschen, he said it took a few losses for them to come up with the idea of a hold down clamp to hold the rocket in place until full thrust was attained. Prior to that time, they'd light the engine, thrust would run up, and there was a time when thrust just equaled weight - and if it was a calm day - well, everything would go well. If there was a strong breeze off the Baltic Sea, the rocket would drift and most likely run into something before it cleared the ground.

https://www.youtube.com/watch?v=Ii7uwp1SRIM

I suspect there is another version of the hold down clamp for landing rockets that is awaiting development. One that will locate the rocket and grab it securing it to the landing platform.


On Saturday, April 9, 2016 at 10:36:45 AM UTC+12, Rick Jones wrote:
Jeff Findley wrote:
Also, and likely the most historic, the first stage landed successfully
on the barge, which is a first!

I managed to get online to see the youtube-carried technical feed.
How long does the stage just sit there bobbing in the ocean with the
barge waiting for a rogueish wave to come along and upset the apple
cart?

rick
--
web2.0 n, the dot.com reunion tour...
these opinions are mine, all mine; HPE might not want them anyway...
feel free to post, OR email to rick.jones2 in hpe.com but NOT BOTH...

On 9/04/2016 8:24 AM, Jeff Findley wrote:

I'm tired of people saying "chemical propulsion is too expensive" when
the fuel is so damn cheap! Fuel costs are *not* the problem.
Skylon/Sabre is a solution to a problem which *does not exist*!

Skylon/Sabre is not about reducing the amount of fuel consumed.

Sylvia.

In article ,
ess says...

On 9/04/2016 8:24 AM, Jeff Findley wrote:

I'm tired of people saying "chemical propulsion is too expensive" when
the fuel is so damn cheap! Fuel costs are *not* the problem.
Skylon/Sabre is a solution to a problem which *does not exist*!

Skylon/Sabre is not about reducing the amount of fuel consumed.

Sorry, I was being sloppy and lumping the mass of the oxidizer in with
the fuel.

How about this. LOX is one of the cheapest fluids used in the aerospace
industry. It's literally made from air. Trying to reduce LOX
consumption is quite counter-intuitive if reducing launch costs is the
goal.

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 10/04/2016 6:34 AM, Jeff Findley wrote:
In article ,
ess says...

On 9/04/2016 8:24 AM, Jeff Findley wrote:

I'm tired of people saying "chemical propulsion is too expensive" when
the fuel is so damn cheap! Fuel costs are *not* the problem.
Skylon/Sabre is a solution to a problem which *does not exist*!

Skylon/Sabre is not about reducing the amount of fuel consumed.

Sorry, I was being sloppy and lumping the mass of the oxidizer in with
the fuel.

How about this. LOX is one of the cheapest fluids used in the aerospace
industry. It's literally made from air. Trying to reduce LOX
consumption is quite counter-intuitive if reducing launch costs is the
goal.

Jeff


The point of Sabre is not to reduce the amount of LOX that is consumed,
the cost of LOX being, as you point out, negligible in this context.

The goal is to build an SSTO vehicle, with the economic advantages that
brings. Sabre is a means to that end, because it reduces the amount of
LOX that has to be *lifted*, and allows atmospheric nitrogen to be used
as reaction mass during the air-breathing phase.

Sylvia.

Alright, I've stated my prejudices against the Skylon's approach to build a LACE propulsion system. SO, let's look at this more closely and see if my prejudice is justified.

A Liquid Air Cycle Engine (LACE) is a type of spacecraft propulsion engine that attempts to increase its efficiency by gathering part of its oxidizer from the atmosphere. A liquid air cycle engine uses liquid hydrogen (LH2) fuel to liquefy the air.

At its atmospheric boiling point, the specific (constant-pressure) heat
capacity of

liquid hydrogen is about 14.4 J/(g K).
liquid oxygen is about 1 J/(g K).
liquid nitrogen is about 1 J/(g K).

The heat of fusion of LH2: 58.5 J/(g K)

The heat of vaporization of LH2 is 452 J/g
The heat of vaporization of LOX is 216 J/g
The heat of vaporization of LN2 is 199 J/g

Boiling point: LH2: 20.28 K
LOX: 90.19 K
LN2: 77.00 K

Now, at room temperature (293 K) a pure oxygen atmosphere will require 203 Joules to reduce a gram of gas to the boiling point of LOX. It will take another 216 J per g to liquefy the oxygen. A total of 419 J per g of oxygen..

Now a solid block of hydrogen at 14 K will absorb 76x14.4 J = 1,094 J rising to 90.19 K, and will also absorb an added 58.5 J along with another 452 J for each gram. A grand total of 1,605 J. So, each gram will have sufficient capacity to absorb energy to liquefy 3.83 grams of oxygen at room temperature.

To obtain 5.5 grams of oxygen for each gram of hydrogen which is the ideal O:F ratio, we must absorb 2,095 J if we are to liquefy all the oxygen. This means we must raise the temperature to room temperature. Of course doing this, allows the oxygen to boil and then to rise in temperature to room temperature, which reduces the energy required to that lost in the process.

So, how is this supposed to work then?

Liquid hydrogen runs through a heat exchanger which cools incoming air. That air eventually liquefies the oxygen, but not the nitrogen which boils at a lower temperature. The cold nitrogen gas is used to chill the air, so that the hydrogen doesn't have to. The purified oxygen, also chills the air, so the hydrogen doesn't have to.

So, by boiling away a gram of solid hydrogen and raising it to room temperature, 2,095 Joules of energy is absorbed in the process. This liquefies 5.5 grams of oxygen starting at room temperature, assuming the nitrogen is recovered.

With air, 78% is nitrogen and 21% oxygen. By liquefying the oxygen in the air, the nitrogen remains gaseous. So, it can flow through a heat exchanger and exit the craft, reducing the work the liquid hydrogen has to do. The lox in a similar fashion can absorb heat to reduce the load on the liquid hydrogen process.

km/sec R..... K...... J/gram grams grams

0.30 500 277.78 403.59 1.01 0.47
0.60 750 416.67 542.48 1.36 0.82
0.90 1000 555.56 681.37 1.70 1.16
1.20 1500 833.33 959.14 2.40 1.86
1.50 2000 1,111.11 1,236.92 3.09 2.55
1.80 3000 1,666.67 1,792.48 4.48 3.94
2.10 4000 2,222.22 2,348.03 5.87 5.33
2.40 5000 2,777.78 2,903.59 7.26 6.72

At 5.5 to 1 and 60 atmosphere pressure, the flame temperature is 3400 K.

I don't see how this can work in practice. At high speeds there isn't enough time for the air to be chilled. If the air is stopped and held until chilled, the drag and temperatures become too high.

Evaporating liquid hydrogen in a heat exchanger could cool ambient air at a certain rate to extract LOX seems doable. Yet, looking at LOX production plants it takes about 800 kWh to produce a ton of LOX from 5 tons of air. That's 2880 Joules per gram. That's the amount of energy absorbed by bringing 1 gram of solid hydrogen up to room temperature.

https://books.google.co.nz/books?id=...%20air&f=false


So, I don't see how it can work realistically.



..
On Sunday, April 10, 2016 at 2:41:49 PM UTC+12, Sylvia Else wrote:
On 10/04/2016 6:34 AM, Jeff Findley wrote:
In article ,
ess says...

On 9/04/2016 8:24 AM, Jeff Findley wrote:

I'm tired of people saying "chemical propulsion is too expensive" when
the fuel is so damn cheap! Fuel costs are *not* the problem.
Skylon/Sabre is a solution to a problem which *does not exist*!

Skylon/Sabre is not about reducing the amount of fuel consumed.

Sorry, I was being sloppy and lumping the mass of the oxidizer in with
the fuel.

How about this. LOX is one of the cheapest fluids used in the aerospace
industry. It's literally made from air. Trying to reduce LOX
consumption is quite counter-intuitive if reducing launch costs is the
goal.

Jeff


The point of Sabre is not to reduce the amount of LOX that is consumed,
the cost of LOX being, as you point out, negligible in this context.

The goal is to build an SSTO vehicle, with the economic advantages that
brings. Sabre is a means to that end, because it reduces the amount of
LOX that has to be *lifted*, and allows atmospheric nitrogen to be used
as reaction mass during the air-breathing phase.

Sylvia.

On 10/04/2016 7:27 PM, William Mook wrote:
Alright, I've stated my prejudices against the Skylon's approach to
build a LACE propulsion system. SO, let's look at this more closely
and see if my prejudice is justified.

A Liquid Air Cycle Engine (LACE) is a type of spacecraft propulsion
engine that attempts to increase its efficiency by gathering part of
its oxidizer from the atmosphere. A liquid air cycle engine uses
liquid hydrogen (LH2) fuel to liquefy the air.

At its atmospheric boiling point, the specific (constant-pressure)
heat capacity of

liquid hydrogen is about 14.4 J/(g K). liquid oxygen is about 1 J/(g
K). liquid nitrogen is about 1 J/(g K).

The heat of fusion of LH2: 58.5 J/(g K)

The heat of vaporization of LH2 is 452 J/g The heat of vaporization
of LOX is 216 J/g The heat of vaporization of LN2 is 199 J/g

Boiling point: LH2: 20.28 K LOX: 90.19 K LN2: 77.00 K

Now, at room temperature (293 K) a pure oxygen atmosphere will
require 203 Joules to reduce a gram of gas to the boiling point of
LOX. It will take another 216 J per g to liquefy the oxygen. A
total of 419 J per g of oxygen.

Now a solid block of hydrogen at 14 K will absorb 76x14.4 J = 1,094 J
rising to 90.19 K, and will also absorb an added 58.5 J along with
another 452 J for each gram. A grand total of 1,605 J. So, each
gram will have sufficient capacity to absorb energy to liquefy 3.83
grams of oxygen at room temperature.

To obtain 5.5 grams of oxygen for each gram of hydrogen which is the
ideal O:F ratio, we must absorb 2,095 J if we are to liquefy all the
oxygen. This means we must raise the temperature to room
temperature. Of course doing this, allows the oxygen to boil and
then to rise in temperature to room temperature, which reduces the
energy required to that lost in the process.

So, how is this supposed to work then?

Liquid hydrogen runs through a heat exchanger which cools incoming
air. That air eventually liquefies the oxygen, but not the nitrogen
which boils at a lower temperature. The cold nitrogen gas is used to
chill the air, so that the hydrogen doesn't have to. The purified
oxygen, also chills the air, so the hydrogen doesn't have to.

So, by boiling away a gram of solid hydrogen and raising it to room
temperature, 2,095 Joules of energy is absorbed in the process. This
liquefies 5.5 grams of oxygen starting at room temperature, assuming
the nitrogen is recovered.

With air, 78% is nitrogen and 21% oxygen. By liquefying the oxygen
in the air, the nitrogen remains gaseous. So, it can flow through a
heat exchanger and exit the craft, reducing the work the liquid
hydrogen has to do. The lox in a similar fashion can absorb heat to
reduce the load on the liquid hydrogen process.

km/sec R..... K...... J/gram grams grams

0.30 500 277.78 403.59 1.01 0.47 0.60 750 416.67 542.48 1.36
0.82 0.90 1000 555.56 681.37 1.70 1.16 1.20 1500 833.33 959.14
2.40 1.86 1.50 2000 1,111.11 1,236.92 3.09 2.55 1.80 3000 1,666.67
1,792.48 4.48 3.94 2.10 4000 2,222.22 2,348.03 5.87 5.33 2.40 5000
2,777.78 2,903.59 7.26 6.72

At 5.5 to 1 and 60 atmosphere pressure, the flame temperature is 3400
K.

I don't see how this can work in practice. At high speeds there
isn't enough time for the air to be chilled. If the air is stopped
and held until chilled, the drag and temperatures become too high.

Evaporating liquid hydrogen in a heat exchanger could cool ambient
air at a certain rate to extract LOX seems doable. Yet, looking at
LOX production plants it takes about 800 kWh to produce a ton of LOX
from 5 tons of air. That's 2880 Joules per gram. That's the amount
of energy absorbed by bringing 1 gram of solid hydrogen up to room
temperature.

https://books.google.co.nz/books?id=...%20air&f=false



So, I don't see how it can work realistically.



. On Sunday, April 10, 2016 at 2:41:49 PM UTC+12, Sylvia Else wrote:
On 10/04/2016 6:34 AM, Jeff Findley wrote:
In article ,
ess says...

On 9/04/2016 8:24 AM, Jeff Findley wrote:

I'm tired of people saying "chemical propulsion is too
expensive" when the fuel is so damn cheap! Fuel costs are
*not* the problem. Skylon/Sabre is a solution to a problem
which *does not exist*!

Skylon/Sabre is not about reducing the amount of fuel
consumed.

Sorry, I was being sloppy and lumping the mass of the oxidizer in
with the fuel.

How about this. LOX is one of the cheapest fluids used in the
aerospace industry. It's literally made from air. Trying to
reduce LOX consumption is quite counter-intuitive if reducing
launch costs is the goal.

Jeff


The point of Sabre is not to reduce the amount of LOX that is
consumed, the cost of LOX being, as you point out, negligible in
this context.

The goal is to build an SSTO vehicle, with the economic advantages
that brings. Sabre is a means to that end, because it reduces the
amount of LOX that has to be *lifted*, and allows atmospheric
nitrogen to be used as reaction mass during the air-breathing
phase.

Sylvia.

Sabre is not a LACE. The air is only cooled to the vapour phase
boundary, not liquified. The cycle would be less efficient if the air
were liquified (even in part).

The system involves cooling the air at the rate it arrives. If this is
not achieved, then the engine won't work, but you can't a priori say
that it cannot be achieved.

Sylvia/

In article ,
ess says...

On 10/04/2016 6:34 AM, Jeff Findley wrote:
In article ,
ess says...

On 9/04/2016 8:24 AM, Jeff Findley wrote:

I'm tired of people saying "chemical propulsion is too expensive" when
the fuel is so damn cheap! Fuel costs are *not* the problem.
Skylon/Sabre is a solution to a problem which *does not exist*!

Skylon/Sabre is not about reducing the amount of fuel consumed.

Sorry, I was being sloppy and lumping the mass of the oxidizer in with
the fuel.

How about this. LOX is one of the cheapest fluids used in the aerospace
industry. It's literally made from air. Trying to reduce LOX
consumption is quite counter-intuitive if reducing launch costs is the
goal.

The point of Sabre is not to reduce the amount of LOX that is consumed,
the cost of LOX being, as you point out, negligible in this context.

The goal is to build an SSTO vehicle, with the economic advantages that
brings. Sabre is a means to that end, because it reduces the amount of
LOX that has to be *lifted*, and allows atmospheric nitrogen to be used
as reaction mass during the air-breathing phase.

By the time Sabre/Skylon flies it may very well have to compete with a
next generation fully reusable TSTO. A fully reusable, LOX/methane,
TSTO is what SpaceX plans on pursuing as their Mars launch vehicle.

I welcome the competition, but I just don't see the point of wings and
intakes on a vehicle that is trying to go to LEO.

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.