Author Topic: Could Merlin 1D lead to the return of Falcon 5?  (Read 17664 times)

Offline sojourner

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Could Merlin 1D lead to the return of Falcon 5?
« on: 04/21/2011 07:08 pm »
Hi,
  Long time lurker on this forum.  I am not in the industry, just a space flight enthusiast, so I make no claim to knowing if this is possible. 

Any way,  since the Merlin 1D has been  touted as having this incredible boost in thrust over Merlin 1c,  couldn't they remove some engines from F9 when  launching smaller payloads?  Thus lowering cost?

Offline Robotbeat

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Re: Could Merlin 1D lead to the return of Falcon 5?
« Reply #1 on: 04/21/2011 07:11 pm »
I believe Shotwell said that they don't want to go back to Falcon 5 because it's unstable.
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Offline edkyle99

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Re: Could Merlin 1D lead to the return of Falcon 5?
« Reply #2 on: 04/21/2011 07:21 pm »
Hi,
  Long time lurker on this forum.  I am not in the industry, just a space flight enthusiast, so I make no claim to knowing if this is possible. 

Any way,  since the Merlin 1D has been  touted as having this incredible boost in thrust over Merlin 1c,  couldn't they remove some engines from F9 when  launching smaller payloads?  Thus lowering cost?

Merlin 1D only offers a 12% increase in thrust from the previously announced plans for Merlin 1C (140K versus 125K), so no engine reduction is possible for the Falcon 9 Block 2 currently cataloged in the SpaceX User's Guide. 

It might be possible to launch a Block 1 Falcon 9 using only seven Merlin 1D engines, but SpaceX is not publicly offering Block 1 as a "buy" option. 

 - Ed Kyle
« Last Edit: 04/21/2011 07:21 pm by edkyle99 »

Offline sojourner

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Re: Could Merlin 1D lead to the return of Falcon 5?
« Reply #3 on: 04/21/2011 07:31 pm »
^Ah, thanks for the reply!

Offline aquanaut99

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Re: Could Merlin 1D lead to the return of Falcon 5?
« Reply #4 on: 04/21/2011 07:34 pm »
Also, doesn't having a more powerful engine (Merlin 1D) while keeping the 9-engine config reduce LOM by offering better engine-out capacity?
« Last Edit: 04/21/2011 07:35 pm by aquanaut99 »

Offline Nomadd

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Re: Could Merlin 1D lead to the return of Falcon 5?
« Reply #5 on: 04/22/2011 01:44 pm »
 It depends on the how much SpaceX is spending to produce engines. There's a pretty big market hole between F1e and F9 they might like to fill, but if they're cranking out Merlins at $2 million each, it might not reduce overall launch costs enough to be worthwhile. Spending $200 million to develop a vehicle that would save you $8 million a launch probably wouldn't make much sense today.
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Online Giovanni DS

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Re: Could Merlin 1D lead to the return of Falcon 5?
« Reply #6 on: 04/22/2011 01:55 pm »
Perhaps a "F6" or "F7" without tank stretch would be possible offering the current F9 performance at a reduced cost.

F9 would jump to the mentioned 16T payload capability (with tank stretch) and that would most likely not be required for some payloads, this reduced version could make sense.

Offline Sen

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Re: Could Merlin 1D lead to the return of Falcon 5?
« Reply #7 on: 04/23/2011 12:25 am »
What would be the point of spending the money? To save 2-4 merlin (1-2 million per) engines? Cheaper to Fly a stock Falcon 9 "light" on payload, or with small/microsats.
« Last Edit: 04/23/2011 01:10 am by Sen »

Offline DaveH62

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Re: Could Merlin 1D lead to the return of Falcon 5?
« Reply #8 on: 04/23/2011 12:57 am »
Would it make more sense to have a Falcon 1 Heavy, using the Falcon 9 Heavy tech fuel sharing technology on the smaller rocket? I doubt its feasible to slice the market this thin, but it might be a cheaper path than a separate Falcon 5 platform.

Offline Jim

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Re: Could Merlin 1D lead to the return of Falcon 5?
« Reply #9 on: 04/23/2011 01:00 am »
No, 3 cores and a new pad is not going to cheaper

Offline neilh

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Re: Could Merlin 1D lead to the return of Falcon 5?
« Reply #10 on: 04/23/2011 01:33 am »
There's plenty of downsides. The only advantage I see is saving the cost of a few engines, but considering the effort they're putting into mass-producing engines, the marginal cost per engine is likely to be a relatively low portion of their total launch costs.
« Last Edit: 04/23/2011 01:33 am by neilh »
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Offline RocketEconomist327

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Re: Could Merlin 1D lead to the return of Falcon 5?
« Reply #11 on: 04/23/2011 02:30 am »
There will be no Falcon 5 of any iteration.

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Offline sdsds

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Re: Could Merlin 1D lead to the return of Falcon 5?
« Reply #12 on: 04/24/2011 06:34 am »
The piece of Falcon 5 I would most like to see resurrected would be the upper stage with two upgraded Kestrel engines.  Used as a third stage atop Falcon Heavy, a stage with 8 tonnes of propellant might take 9 tonnes of payload all the way to GEO!
« Last Edit: 04/24/2011 01:58 pm by sdsds »
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Offline gospacex

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Re: Could Merlin 1D lead to the return of Falcon 5?
« Reply #13 on: 04/24/2011 01:26 pm »
I don't see why it is impossible to fit unmodified F9 first stage with less than 9 engines. DIRECT proposed to do the same technique with J130.

Offline neilh

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Re: Could Merlin 1D lead to the return of Falcon 5?
« Reply #14 on: 04/24/2011 04:34 pm »
Sure, it's not impossible to have a wide array of engine configurations, but right now SpaceX wants to standardize as much as possible. 

Another way to think of the issue: Over the next 10 years, how much additional revenue could SpaceX get from spending the development and testing dollars to get a proven Falcon 5, that they wouldn't be able to get otherwise? What is the return on investment?
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Offline Comga

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Re: Could Merlin 1D lead to the return of Falcon 5?
« Reply #15 on: 04/25/2011 12:29 am »
Merlin 1D only offers a 12% increase in thrust from the previously announced plans for Merlin 1C (140K versus 125K), so no engine reduction is possible for the Falcon 9 Block 2 currently cataloged in the SpaceX User's Guide. 

It might be possible to launch a Block 1 Falcon 9 using only seven Merlin 1D engines, but SpaceX is not publicly offering Block 1 as a "buy" option. 

 - Ed Kyle

That doesn't sound right.  Merlin 1-C is 95 klbf AFAIK.  Merlin 1-D is 140 klbf as you say.  (Up from 135 klbf in a January projection)

9*95=855  5*140=700 so a Falcon 5(1D) would have have only 82% of the thrust of the Falcon 9(1C).

On the other hand, The Falcon 9 will require significant structural redesign to accommodate the higher thrust.  This may be part of what we are seeing in the longer stages of the Falcon Heavy.  If they could grow the Merlin 1-D to 165-170 klbf, about a 20% additional increase, they would have a proven structure and launch facility and a less expensive rocket with existing tooling.  Would it be worth it?  I wouldn't know.

Then there remains Shotwell's comment about instability.
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline edkyle99

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Re: Could Merlin 1D lead to the return of Falcon 5?
« Reply #16 on: 04/25/2011 02:32 am »
Merlin 1D only offers a 12% increase in thrust from the previously announced plans for Merlin 1C (140K versus 125K), so no engine reduction is possible for the Falcon 9 Block 2 currently cataloged in the SpaceX User's Guide. 

It might be possible to launch a Block 1 Falcon 9 using only seven Merlin 1D engines, but SpaceX is not publicly offering Block 1 as a "buy" option. 

 - Ed Kyle

That doesn't sound right.  Merlin 1-C is 95 klbf AFAIK.  Merlin 1-D is 140 klbf as you say.  (Up from 135 klbf in a January projection)

9*95=855  5*140=700 so a Falcon 5(1D) would have have only 82% of the thrust of the Falcon 9(1C).

On the other hand, The Falcon 9 will require significant structural redesign to accommodate the higher thrust.  This may be part of what we are seeing in the longer stages of the Falcon Heavy.  If they could grow the Merlin 1-D to 165-170 klbf, about a 20% additional increase, they would have a proven structure and launch facility and a less expensive rocket with existing tooling.  Would it be worth it?  I wouldn't know.

The "Merlin" (I'm not sure SpaceX ever specifically gave it a name*) version shown in the SpaceX User's Guide for Falcon 9 Block 2 was to produce 125Klbs thrust at sea level.  That's the 12% difference compared to Merlin 1D.  The Merlin 1C version used on the first two Falcon 9 launches (Block 1 versions) produced 95Klb thrust at sea level.  That version is not shown in the Guide or, really, on the SpaceX web site, at least not in complete form.

The only way to gain significant performance improvement from higher thrust is to make the rocket carry more propellant, which means that it either has to be stretched or "fattened". 

 - Ed Kyle

*The Users Guide still posted on the SpaceX web site says "Nine SpaceX Merlin engines power the Falcon 9 first stage with 125,000 lbf sea level thrust per engine, for a total thrust on liftoff of just over 1.1 million lbf."

The Guide also states that "The initial flights of the Falcon 9, currently planned in 2009 and 2010, use the Falcon 9 Block 1.  Beginning in late 2010/early 2011, SpaceX will begin launching the Falcon 9 Block 2. Block 2 features increased engine thrust, decreased launch vehicle dry mass, and increased propellant load ‐ combined with lessons learned from the flights of the Falcon 9 Block 1. This results in increased mass‐to‐orbit performance for the Falcon 9 Block 2 when compared with Block 1 performance. This performance is shown in the Falcon 9 performance tables presented later in this document."
« Last Edit: 04/25/2011 02:41 am by edkyle99 »

Offline notsorandom

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Re: Could Merlin 1D lead to the return of Falcon 5?
« Reply #17 on: 04/25/2011 02:56 am »
Then there remains Shotwell's comment about instability.
What was the context of that quote? Is she saying that it would be unstable in flight? I would be interested in hear why that would be so.

Offline Comga

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Re: Could Merlin 1D lead to the return of Falcon 5?
« Reply #18 on: 04/25/2011 03:51 am »
Ed,
SpaceX documentation on the web is inconsistent and incomplete. 
All SpaceX vehicle performance projections are moving targets, as are availability dates.
Can we agree on this?

As such, the latest statements about the thrust of the Merlin 1D is that it will not be 9/5 of the value for which the current Falcon 9 was designed.  Therefore, the answer to the question in the title of this thread is "Not directly and without another another complete redesign." 
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline sojourner

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Re: Could Merlin 1D lead to the return of Falcon 5?
« Reply #19 on: 01/18/2012 08:58 pm »
So, now with the announcement of Stratolaunch, what do you guys think?

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