Author Topic: SpaceX Falcon Heavy Discussion (Thread 6)  (Read 533372 times)

Offline docmordrid

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Re: SpaceX Falcon Heavy Discussion (Thread 6)
« Reply #340 on: 12/27/2017 05:58 am »
>
I have failed to find a nice mass or volume number for the satellites.
>
I've failed to find any source saying the volume for the satellite is between 3m^3 and 6m^3, and not (say) 1m^3.
>

Here ya go....
« Last Edit: 12/27/2017 05:59 am by docmordrid »
DM

Offline Jimmy Murdok

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Re: SpaceX Falcon Heavy Discussion (Thread 6)
« Reply #341 on: 12/27/2017 09:09 am »
Even if the fairing is upgraded, I fail to see how the long 20t Bigelow module or a new PAF can hold the weight of the horizontal integration.
I think the decission is related to vertical integration, fairing and PAF are secondary items.
FH is just great for GTO, Mars and hopefully some sort of propellant depot filled once in vertical.
My 0,02

Offline speedevil

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Re: SpaceX Falcon Heavy Discussion (Thread 6)
« Reply #342 on: 12/27/2017 01:14 pm »
>
I have failed to find a nice mass or volume number for the satellites.
>
I've failed to find any source saying the volume for the satellite is between 3m^3 and 6m^3, and not (say) 1m^3.
>

Here ya go....

I have problems with this. This gives the satellite body dimensions as 4*1.8*1.2m - 8.6m^3, so a completely naive view might be that ~6 satellites might fit inside the fairing.

However, Iridium-next satellite dimensions are from one source given as  3.1 m x 2.4 m x 1.5 m - 11.1m^3, and that launched ten.

Iridium weighs over twice as much.
4*1.8*1.2 is also notably rather larger than a refrigerator (annoyingly, I can find lots of people repeating this claim, but can't find a source at the 2015 announcement, other transcripts of what Elon has said, or ...)

If we take 4*1.8*1.2 as gospel, and not unfolded, this is also for example consistent with a pie-wedge shape 4m high, 1.8m wide, with the segments being 1.2m along the outside diameter. this allows fitting 22 into the existing fairing.

If the 'size of a refrigerator' is to be believed, then 1.8*1.2*1.2 would about work, with around 40 fitting, assuming rectangular boxes.
Either of these would also be about consistent with Iridium satellite density, not way under it.

Offline envy887

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Re: SpaceX Falcon Heavy Discussion (Thread 6)
« Reply #343 on: 12/27/2017 01:33 pm »
>
I have failed to find a nice mass or volume number for the satellites.
>
I've failed to find any source saying the volume for the satellite is between 3m^3 and 6m^3, and not (say) 1m^3.
>

Here ya go....

I have problems with this. This gives the satellite body dimensions as 4*1.8*1.2m - 8.6m^3, so a completely naive view might be that ~6 satellites might fit inside the fairing.

However, Iridium-next satellite dimensions are from one source given as  3.1 m x 2.4 m x 1.5 m - 11.1m^3, and that launched ten.

Iridium weighs over twice as much.
4*1.8*1.2 is also notably rather larger than a refrigerator (annoyingly, I can find lots of people repeating this claim, but can't find a source at the 2015 announcement, other transcripts of what Elon has said, or ...)

If we take 4*1.8*1.2 as gospel, and not unfolded, this is also for example consistent with a pie-wedge shape 4m high, 1.8m wide, with the segments being 1.2m along the outside diameter. this allows fitting 22 into the existing fairing.

If the 'size of a refrigerator' is to be believed, then 1.8*1.2*1.2 would about work, with around 40 fitting, assuming rectangular boxes.
Either of these would also be about consistent with Iridium satellite density, not way under it.

The dimensions given are used for the orbital decay drag calculation, so most definitely the unfolded dimensions.

I think Iridium birds are 2.4 m tall and 1.5 m thick, with 3.1 m being the unfolded span of the arrays. If the SpaceX birds are designed along the same lines, they would be 1.8 m tall, 1.2 m thick, with a 4 m array span. Assuming the folded width maintains around the same 80% size ratio to Iridium, they could fit at least 6 in a ring (Iridium fits 5). They could easily fit 3 rings high in the current fairing, plus a small ring of 3 on top, for a total of 21. If they get 7 per ring and 4 in a smaller ring on top, that's 25 per launch, or exactly 1/2 an orbital plane. It's also about 10,000 kg including dispensers, which is about what F9 Block 5 will launch to to 1000 km polar orbit with booster RTLS.

Falcon Heavy can probably do about 25,000 kg to that orbit with booster RTLS. If they made a long fairing just barely bigger than the longest ULA fairing (by about 0.2 meters), they could stack 7 rings high of 7 each, and another 3 on top, for a total of 52 birds and 21,000 kg including dispensers. Well within FH payload capability, and fills 72 of the 83 of the planes in 1 launch each.

So it seems likely to me that if they use Falcon Heavy for the constellation, they will build a longer fairing to fit 50 satellites inside. Otherwise, they will use F9 and cram 25 into fairing 2.0 on each launch.
« Last Edit: 12/27/2017 01:54 pm by envy887 »

Offline oldAtlas_Eguy

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Re: SpaceX Falcon Heavy Discussion (Thread 6)
« Reply #344 on: 12/27/2017 06:32 pm »
The dimensions give a size slightly larger than that of an Iridium sat and therefore only at best 10 will fit in the F9 faring. But that is also 8X that of a refrigerator in size. A refrigerator is more like 2mX.9mX.6m.

At 10 the payload weight is only ~5mt and with a longer faring  at most with a faring lengthened by 4+m of a count of 15 sats and a payload mass of 7.5mt. Which still is a F9 payload size and not that of a FH.

And we are wandering OT for this thread.

The Starlink sat discussion should go to this thread:
http://forum.nasaspaceflight.com/index.php?topic=44288.new#new
« Last Edit: 12/27/2017 07:55 pm by oldAtlas_Eguy »

Offline wannamoonbase

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Re: SpaceX Falcon Heavy Discussion (Thread 6)
« Reply #345 on: 12/27/2017 07:09 pm »
SpaceX is likely getting closer to pegging down the cost variables of reuseability.

Deploying the constellation on the F9 or the FH, I think, is still an unknown.  Will using more Block 5 F9's be cheaper than   Block 5 FH's?

I don't think anyone knows at this point.  But we are getting closer to those numbers and the start of the constellation, and that's very exciting.
Wildly optimistic prediction, Superheavy recovery on IFT-4 or IFT-5

Offline Okie_Steve

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Re: SpaceX Falcon Heavy Discussion (Thread 6)
« Reply #346 on: 12/28/2017 04:38 am »
One topic of recurring speculation is what payloads would need the lift capability of the heavy. Which leads me to a possibly dumb question since I know nothing about satellite architecture. Would it be reasonable for some government agency with a name ending in "A" to take a standard - if there is such a thing - recon sat and add tankage for lots more propellant for station keeping and manuvering? Or are all the systems so interrelated that it would be better to start from scratch building a big honking payload like that? With all the lead time that implies.

Offline IanThePineapple

Re: SpaceX Falcon Heavy Discussion (Thread 6)
« Reply #347 on: 12/28/2017 04:39 am »
One topic of recurring speculation is what payloads would need the lift capability of the heavy. Which leads me to a possibly dumb question since I know nothing about satellite architecture. Would it be reasonable for some government agency with a name ending in "A" to take a standard - if there is such a thing - recon sat and add tankage for lots more propellant for station keeping and manuvering? Or are all the systems so interrelated that it would be better to start from scratch building a big honking payload like that? With all the lead time that implies.

It would take years to redesign a sat bus, it's not just duct taping more tanks on and using straws to connect them.

Then you need to build it after designing.

Offline Okie_Steve

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Re: SpaceX Falcon Heavy Discussion (Thread 6)
« Reply #348 on: 12/28/2017 04:46 am »
OK, thanks. I suppose there might be a few other issues about launching 20 or 30 tons of hydrazine etc too. :o

Offline MikeAtkinson

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Re: SpaceX Falcon Heavy Discussion (Thread 6)
« Reply #349 on: 12/28/2017 08:54 am »
The dimensions give a size slightly larger than that of an Iridium sat and therefore only at best 10 will fit in the F9 faring. But that is also 8X that of a refrigerator in size. A refrigerator is more like 2mX.9mX.6m.

At 10 the payload weight is only ~5mt and with a longer faring  at most with a faring lengthened by 4+m of a count of 15 sats and a payload mass of 7.5mt. Which still is a F9 payload size and not that of a FH.

And we are wandering OT for this thread.

The Starlink sat discussion should go to this thread:
http://forum.nasaspaceflight.com/index.php?topic=44288.new#new

There are perhaps better ways of packing the satellites and deployment structure than used by Iridium. Perhaps by trading satellite mass with deployment structure mass.

Offline AncientU

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Re: SpaceX Falcon Heavy Discussion (Thread 6)
« Reply #350 on: 12/28/2017 11:23 am »
The dimensions give a size slightly larger than that of an Iridium sat and therefore only at best 10 will fit in the F9 faring. But that is also 8X that of a refrigerator in size. A refrigerator is more like 2mX.9mX.6m.

At 10 the payload weight is only ~5mt and with a longer faring  at most with a faring lengthened by 4+m of a count of 15 sats and a payload mass of 7.5mt. Which still is a F9 payload size and not that of a FH.

And we are wandering OT for this thread.

The Starlink sat discussion should go to this thread:
http://forum.nasaspaceflight.com/index.php?topic=44288.new#new

There are perhaps better ways of packing the satellites and deployment structure than used by Iridium. Perhaps by trading satellite mass with deployment structure mass.

Packing factor and density has been on SpaceX's radar from day one... they know how many are going to be launched, and they know the vehicles available to launch them.  We just have to wait until the first ones are integrated to see the solution that has been optimized.

For FH, I suspect that they are waiting for the USAF to foot the bill for a longer fairing.
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Offline Chris Bergin

Re: SpaceX Falcon Heavy Discussion (Thread 6)
« Reply #351 on: 12/29/2017 10:56 pm »
OK. Gave it a chance for some good rebuttal of that paper having a go at attacking Falcon Heavy, but a lot of you fell into the trap these sites prey on.

"I'm outraged by this: (links site.....site says thanks for all the visitors you're sending us)."

Followed by 15 more again quoting the post with the link and adding the "I'm also outraged" style comment. (That site says "I feed off your hate. Please, be more outraged!")

That's how some media work.

However, I didn't actually read it! Now I'm told it was a far right angled publication, so at the risk of getting a slap from that fella in Alabama who literally is the worst horseman I've ever seen (I ride, so I know), thread trimmed. :)

I don't think any of you will be weeping about that mini-thread being removed. ;)

Hey, how about that big rocket! Let's keep talking about that.
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Offline MickQ

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Re: SpaceX Falcon Heavy Discussion (Thread 6)
« Reply #352 on: 12/29/2017 11:33 pm »
Right On, Chris !

Offline clongton

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Re: SpaceX Falcon Heavy Discussion (Thread 6)
« Reply #353 on: 12/30/2017 01:20 pm »
You ROCK Chris! :)
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I started my career on the Saturn-V F-1A engine

Offline Jim

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Re: SpaceX Falcon Heavy Discussion (Thread 6)
« Reply #354 on: 12/30/2017 09:15 pm »


For FH, I suspect that they are waiting for the USAF to foot the bill for a longer fairing.

not happening

Offline clongton

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Re: SpaceX Falcon Heavy Discussion (Thread 6)
« Reply #355 on: 12/30/2017 09:22 pm »

For FH, I suspect that they are waiting for the USAF to foot the bill for a longer fairing.
not happening

If The Air Force wants to launch something that needs a longer fairing they will put out a RFQ for it.
If SpaceX wants to bid on it their bid will need to take into account everything they need to do.
The Air Force will then decide which of the several bidders gets the launch contract based on RFQ requirements, including but not limited to cost..

The AF will allow for reasonable development to be included but they will *not* "pay for" the fairing development.
That's on SpaceX's dime alone.
Chuck - DIRECT co-founder
I started my career on the Saturn-V F-1A engine

Offline envy887

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Re: SpaceX Falcon Heavy Discussion (Thread 6)
« Reply #356 on: 12/30/2017 09:46 pm »

For FH, I suspect that they are waiting for the USAF to foot the bill for a longer fairing.
not happening

If The Air Force wants to launch something that needs a longer fairing they will put out a RFQ for it.
If SpaceX wants to bid on it their bid will need to take into account everything they need to do.
The Air Force will then decide which of the several bidders gets the launch contract based on RFQ requirements, including but not limited to cost..

The AF will allow for reasonable development to be included but they will *not* "pay for" the fairing development.
That's on SpaceX's dime alone.

Right, the DoD would never pay a launch provider for specific launch vehicle upgrades...

https://arstechnica.com/science/2017/06/the-us-military-is-still-paying-a-spacex-competitor-for-rocket-upgrades/

Offline meekGee

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Re: SpaceX Falcon Heavy Discussion (Thread 6)
« Reply #357 on: 12/30/2017 09:52 pm »
The last thing SpaceX needs is to do one-off projects, even if funded, for the USG.

They have StarLink on their mind, and BFR, and everything else is really not that interesting to them.

If they need a bigger fairing for StarLink, they'll make one - but they'll make it like they want to, not like the AF wants to.

Remember that they want to build an entire BFArchitecture on their own dime - that's a lot more than some extended fairing.
ABCD - Always Be Counting Down

Offline guckyfan

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Re: SpaceX Falcon Heavy Discussion (Thread 6)
« Reply #358 on: 12/30/2017 09:56 pm »
The last thing SpaceX needs is to do one-off projects, even if funded, for the USG.

They have StarLink on their mind, and BFR, and everything else is really not that interesting to them.

If they need a bigger fairing for StarLink, they'll make one - but they'll make it like they want to, not like the AF wants to.

Remember that they want to build an entire BFArchitecture on their own dime - that's a lot more than some extended fairing.

I am quite confident with my opinion that SpaceX intends to to be able to do all DoD missions with the Falcon family. That would include vertical integration and a larger fairing. A 2 year timeframe from contract to launch will enable them to design the capabilities after contract award.

Edit: fixed quote
« Last Edit: 12/30/2017 09:57 pm by guckyfan »

Offline meekGee

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Re: SpaceX Falcon Heavy Discussion (Thread 6)
« Reply #359 on: 12/30/2017 10:01 pm »
The last thing SpaceX needs is to do one-off projects, even if funded, for the USG.

They have StarLink on their mind, and BFR, and everything else is really not that interesting to them.

If they need a bigger fairing for StarLink, they'll make one - but they'll make it like they want to, not like the AF wants to.

Remember that they want to build an entire BFArchitecture on their own dime - that's a lot more than some extended fairing.

I am quite confident with my opinion that SpaceX intends to to be able to do all DoD missions with the Falcon family. That would include vertical integration and a larger fairing. A 2 year timeframe from contract to launch will enable them to design the capabilities after contract award.

Edit: fixed quote
Why would they?

They're intent on retiring F9, and moving on the what is literally a new space age.

Plus they want to operate StarLink, which is much more lucrative than an AF contract.

The AF will come along when they're good and ready.  Until then they can fly EELVs.

Also, why antagonize ULAs support base?  The "win" they are aiming for is so large that there's no need for ULA to "lose".

It'd be a distraction and a wasted effort.
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