Author Topic: SpaceX Falcon Heavy Discussion (Thread 3)  (Read 332271 times)

Offline Ben the Space Brit

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Re: SpaceX Falcon Heavy Discussion (Thread 3)
« Reply #180 on: 03/04/2015 03:15 pm »
IIRC, the cross-feed scheme would have four core engines fuelled from the portside booster and four others from the starboard booster with one core engine fuelled from the core tanks. So, a larger core tank would seem to make sense.
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Offline fthomassy

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Re: SpaceX Falcon Heavy Discussion (Thread 3)
« Reply #181 on: 03/04/2015 04:24 pm »
IIRC, the cross-feed scheme would have four core engines fuelled from the portside booster and four others from the starboard booster with one core engine fuelled from the core tanks. So, a larger core tank would seem to make sense.
The one diagram I recall showed cross feed between distribution nodes that feed all engines on a particular core.  So the center core has a node that is fed by three tanks and distributing to all nine engines.  That diagram was very cartoonish but it also seems more intuitive.  Either way I don't see the relationship to tank size.  Same size core and boosters or not ... cross feed or not ... lots of choices to spend money (or not) for performance options.
« Last Edit: 03/05/2015 12:51 pm by fthomassy »
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Offline cdleonard

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Re: SpaceX Falcon Heavy Discussion (Thread 3)
« Reply #182 on: 03/04/2015 05:05 pm »
I agree.  But again, if you include the interstage as an integral part the center core, the length of all 3 cores is pretty close.  In fact, if you remove the domes, the booster cores would be shorter.
The interstage protects the upper-stage engine. The core tank ends below it.

I think it's likely that the domes of the side boosters are part of the tank structure and filled with propellant. For example the space shuttle external tank's nose was filled with LOX.

Offline Lars-J

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Re: SpaceX Falcon Heavy Discussion (Thread 3)
« Reply #183 on: 03/04/2015 05:07 pm »
I agree.  But again, if you include the interstage as an integral part the center core, the length of all 3 cores is pretty close.  In fact, if you remove the domes, the booster cores would be shorter.
The interstage protects the upper-stage engine. The core tank ends below it.

I think it's likely that the domes of the side boosters are part of the tank structure and filled with propellant. For example the space shuttle external tank's nose was filled with LOX.

No, they won't be - because nose still needs to contain the grid fins + hydraulics, plus the RCS thrusters and propellant.

Offline Dave G

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Re: SpaceX Falcon Heavy Discussion (Thread 3)
« Reply #184 on: 03/04/2015 05:43 pm »
IIRC, the cross-feed scheme would have four core engines fuelled from the portside booster and four others from the starboard booster with one core engine fuelled from the core tanks.
I thought it was 3 for each booster and 3 for the center core, but I'm not sure.  Anyone have a reference?

So, a larger core tank would seem to make sense.
if they could get a larger core from Hawthorne to the launch site.

Offline guckyfan

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Re: SpaceX Falcon Heavy Discussion (Thread 3)
« Reply #185 on: 03/04/2015 05:49 pm »
So, a larger core tank would seem to make sense.
if they could get a larger core from Hawthorne to the launch site.

3 from each booster was the speculation for Falcon 9 1.0 because 3 were accessible from each side.

With the new arrangement the speculation for 4 engines each came up. But as far as I know it was never more than speculation.

Offline spacenut

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Re: SpaceX Falcon Heavy Discussion (Thread 3)
« Reply #186 on: 03/04/2015 06:01 pm »
If they can throttle the new upgraded engines, cross feed might not be necessary.  Throttle down the core and throttle up the boosters.  The second stage engine has/is being upgraded also, and it seems to be a much more powerful upgrade. 

Offline TomH

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Re: SpaceX Falcon Heavy Discussion (Thread 3)
« Reply #187 on: 03/04/2015 07:08 pm »
Still, if you use cross-feed and run all engines @ WOT, you have less gravity losses. The question then becomes whether the LV and the payload can take the G-load.

Offline llanitedave

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Re: SpaceX Falcon Heavy Discussion (Thread 3)
« Reply #188 on: 03/04/2015 08:54 pm »
IIRC, the cross-feed scheme would have four core engines fuelled from the portside booster and four others from the starboard booster with one core engine fuelled from the core tanks.
I thought it was 3 for each booster and 3 for the center core, but I'm not sure.  Anyone have a reference?

So, a larger core tank would seem to make sense.
if they could get a larger core from Hawthorne to the launch site.


I've seen wind generator towers transported on two-lane roads as one unit.  They are typically 212 feet in length. 
https://www.wind-watch.org/faq-size.php


The extended side booster of the Falcon Heavy doesn't look like it's much longer than 150 feet, so the length concerns posted here are simply not realistic.
« Last Edit: 03/04/2015 08:57 pm by llanitedave »
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Offline MP99

Re: SpaceX Falcon Heavy Discussion (Thread 3)
« Reply #189 on: 03/05/2015 12:37 am »


Maybe all three are stretched from v1.1.

From the SpaceX website:

http://www.spacex.com/falcon9
Height 68.4 m 224.4 ft

http://www.spacex.com/falcon-heavy
Height 68.4 m 224.4 ft

If you add the u/s stretch, presumably both of those numbers become obsolete. The FH one possibly before the first time it flies.

Cheers, Martin

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Re: SpaceX Falcon Heavy Discussion (Thread 3)
« Reply #190 on: 03/05/2015 12:44 am »
If they can throttle the new upgraded engines, cross feed might not be necessary.  Throttle down the core and throttle up the boosters.  The second stage engine has/is being upgraded also, and it seems to be a much more powerful upgrade. 

Does anyone know any details about upper stage engine upgrades?
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Offline cscott

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Re: SpaceX Falcon Heavy Discussion (Thread 3)
« Reply #191 on: 03/05/2015 01:11 am »
IIRC, the cross-feed scheme would have four core engines fuelled from the portside booster and four others from the starboard booster with one core engine fuelled from the core tanks.
I thought it was 3 for each booster and 3 for the center core, but I'm not sure.  Anyone have a reference?

So, a larger core tank would seem to make sense.
if they could get a larger core from Hawthorne to the launch site.


I've seen wind generator towers transported on two-lane roads as one unit.  They are typically 212 feet in length. 
https://www.wind-watch.org/faq-size.php


The extended side booster of the Falcon Heavy doesn't look like it's much longer than 150 feet, so the length concerns posted here are simply not realistic.
Nobody said that 120' was an absolute limit for road transport.  Just that the number of possible routes drops off a cliff once you pass 120'.  It doesn't matter whether you can transport 220' towers *somewhere*.  The issues is the maximum load length possible on coast-to-coast routes between Hawthorne, McGregor, and the Cape.

Offline Robotbeat

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Re: SpaceX Falcon Heavy Discussion (Thread 3)
« Reply #192 on: 03/05/2015 01:14 am »
Wait, is it quite true, though, that 120' is such a hard (okay, "firm") limit? I got the idea that length has a much less firm limit than height, which obviously over any distance greater than a few miles has serious issues due to bridges. I mean, once you're on the Interstate, it's not like there are that many sharp turns.
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Offline Burninate

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Re: SpaceX Falcon Heavy Discussion (Thread 3)
« Reply #193 on: 03/05/2015 01:22 am »
Wait, is it quite true, though, that 120' is such a hard (okay, "firm") limit? I got the idea that length has a much less firm limit than height, which obviously over any distance greater than a few miles has serious issues due to bridges. I mean, once you're on the Interstate, it's not like there are that many sharp turns.
Turns are probably less of a big deal than height problems.  Slap a 300' cargo a lot of different places in the interstate system (we call them 'hills') and your wheels will be off the ground while the center of the cargo see-saws.  Raise this cargo high up enough that it can survive a gentle hill, and you start to scrape overhead bridges.  Put in dynamic shocks so you can raise or lower it, and even then you can't deal with a deliberate depression under a bridge.
« Last Edit: 03/05/2015 01:34 am by Burninate »

Offline Herb Schaltegger

Re: SpaceX Falcon Heavy Discussion (Thread 3)
« Reply #194 on: 03/05/2015 01:43 am »
Wait, is it quite true, though, that 120' is such a hard (okay, "firm") limit? I got the idea that length has a much less firm limit than height, which obviously over any distance greater than a few miles has serious issues due to bridges. I mean, once you're on the Interstate, it's not like there are that many sharp turns.

On-ramps and off-ramps, however, present all manner of pain-in-the-ass problems for transporting long objects.
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Offline darkenfast

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Re: SpaceX Falcon Heavy Discussion (Thread 3)
« Reply #195 on: 03/05/2015 02:06 am »
Something to remember is that there are different levels of oversized.  There is oversized with a permit that can travel night and day and does not require escort vehicles.  Then there is the kind that DOES require escort and can only travel certain hours.  I don't know the details, but there must be a huge difference in cost and time involved.
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Offline Robotbeat

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Re: SpaceX Falcon Heavy Discussion (Thread 3)
« Reply #196 on: 03/05/2015 02:13 am »
Wait, is it quite true, though, that 120' is such a hard (okay, "firm") limit? I got the idea that length has a much less firm limit than height, which obviously over any distance greater than a few miles has serious issues due to bridges. I mean, once you're on the Interstate, it's not like there are that many sharp turns.

On-ramps and off-ramps, however, present all manner of pain-in-the-ass problems for transporting long objects.
How often would that be necessary?

Anyway, this is all a good argument for Return to Launch Site.
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Offline llanitedave

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Re: SpaceX Falcon Heavy Discussion (Thread 3)
« Reply #197 on: 03/05/2015 02:19 am »
I'm not buying it.  Look up Tonopah, NV,and U.S. 95.  Small town, mountainous terrain.  That's where I've seen those 212' long towers being pulled.  Unless there are major obstacles right outside the front gates of either Hawthorne, McGregor (which is a pretty wide open space, so not likely there) or Cape Canaveral, I doubt there will be any on the interstate route in between.
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Offline BobHk

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Re: SpaceX Falcon Heavy Discussion (Thread 3)
« Reply #198 on: 03/05/2015 04:14 am »
I'm not buying it.  Look up Tonopah, NV,and U.S. 95.  Small town, mountainous terrain.  That's where I've seen those 212' long towers being pulled.  Unless there are major obstacles right outside the front gates of either Hawthorne, McGregor (which is a pretty wide open space, so not likely there) or Cape Canaveral, I doubt there will be any on the interstate route in between.

They look kinda like this:

https://i.imgur.com/3YZfnNg.jpg

And this:

http://www.spacex.com/files/assets/img/122908-oversized.jpg
« Last Edit: 03/05/2015 04:15 am by BobHk »

Offline MP99

Re: SpaceX Falcon Heavy Discussion (Thread 3)
« Reply #199 on: 03/05/2015 07:19 am »


Something to remember is that there are different levels of oversized.  There is oversized with a permit that can travel night and day and does not require escort vehicles.  Then there is the kind that DOES require escort and can only travel certain hours.  I don't know the details, but there must be a huge difference in cost and time involved.

F9 v1.0 was sized at the maximum to be transported with minimum fuss. By implication, the constraints on v1.1 transport must be greater.

Cheers, Martin

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