Author Topic: Falcon 1 with drop tanks  (Read 4034 times)

Offline Danderman

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Falcon 1 with drop tanks
« on: 08/10/2011 04:03 PM »
Since SpaceX is now invoking crossfeed in one of its systems, perhaps the solution for the future of Falcon 1 is to use crossfeed on it, as well.

The current Falcon 1 first stage is far too small for the new Merlin 1D engine; rather than stretch the tanks, another approach would be to contain additional prop in drop tanks. The drop tank propellant would be fed to the main engine during the first minutes of flight, and then the tanks would be jettisoned, leaving a first stage with 90 percent of its internal propellant.

The drop tank could be a torus, similar to that used by Briz-M.





Offline krytek

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Re: Falcon 1 with drop tanks
« Reply #1 on: 08/10/2011 04:08 PM »
I was under the impression they were dropping Fhe falcon 1 and 1e all together in favor of Falcon 9.

Offline oldAtlas_Eguy

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Re: Falcon 1 with drop tanks
« Reply #2 on: 08/10/2011 05:09 PM »
There is still 1 F1e flight on the manifest in 2014-2015. Although it is possible the Sat could ride as a secondary on a F9 flight. But at >1MT it is probably too heavy to fly as a secondary on most flights.

The Merlin 1D with throttling will make an excelent engine for the F1e, increasing performance and decreasing costs. This would make the F1e a significant competitor to all the other small LV's out there.

Offline R.Simko

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Re: Falcon 1 with drop tanks
« Reply #3 on: 08/10/2011 05:10 PM »
Since SpaceX is now invoking crossfeed in one of its systems, perhaps the solution for the future of Falcon 1 is to use crossfeed on it, as well.

The current Falcon 1 first stage is far too small for the new Merlin 1D engine; rather than stretch the tanks, another approach would be to contain additional prop in drop tanks. The drop tank propellant would be fed to the main engine during the first minutes of flight, and then the tanks would be jettisoned, leaving a first stage with 90 percent of its internal propellant.

The drop tank could be a torus, similar to that used by Briz-M.






Instead of drop tanks or cross feed, why not just make it a little wider?  Instead of the current 1.7M width, they can make it 2m or there abouts. A little extra width will pick-up a lot of extra fuel carring capacity. 

Offline ChefPat

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Re: Falcon 1 with drop tanks
« Reply #4 on: 08/10/2011 05:11 PM »
Playing Politics with Commercial Crew is Un-American!!!

Offline Comga

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Re: Falcon 1 with drop tanks
« Reply #5 on: 08/10/2011 05:20 PM »
Falcon 1 is defunct because its structure cannot handle the thrust of the Merlin 1D, and there is not enough demand for SpaceX to commit the resources to a structural redesign (and possibly the maintinence of the Kwajalein launch site.) 
Discussions of modifications, including drop tanks which go directly against the SpaceX philosphy of simplicity, are beside the point.

I would really like to see Falcon 1 revived as the 1e.  We have several opportunities to propose smallsat missions that could use a vehicle of this size and promised cost.  However, cost is important, and therefore simplicity is important, so complications like drop tanks wouldn't help.
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline oldAtlas_Eguy

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Re: Falcon 1 with drop tanks
« Reply #6 on: 08/10/2011 05:34 PM »
Falcon 1 Heavy

A M1D F1e would do about 1.1MT to LEO that would make a F1eH do about 3.3MT or with crossfeed about 3.9MT to LEO at a cost of about $20M (using the Heavy 3 core vehicle costing rule that seems to stand up accross multiple LV providers of 2/3 the LEO rate for 3 times the LEO capability).

This would give SpaceX 4 vehicle classes:
F1e 1.1MT
F1eH 3.9MT
F9 10+MT
FH 50+MT

A Taurus II is max 5.1MT to LEO.
« Last Edit: 08/10/2011 05:35 PM by oldAtlas_Eguy »

Offline RanulfC

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Re: Falcon 1 with drop tanks
« Reply #7 on: 08/10/2011 08:54 PM »
Is the lack of a heavy enough thrust structure the only reason for dropping the Falcon-1 design? (Asking 'cause I had some concepts that used the Falcon-1E first stage only :) )

Randy
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Offline Danderman

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Re: Falcon 1 with drop tanks
« Reply #8 on: 08/10/2011 09:29 PM »
Instead of drop tanks or cross feed, why not just make it a little wider?  Instead of the current 1.7M width, they can make it 2m or there abouts. A little extra width will pick-up a lot of extra fuel carring capacity. 

Tooling for wider diameter tankage is expensive.

Online kevin-rf

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Re: Falcon 1 with drop tanks
« Reply #9 on: 08/10/2011 11:10 PM »
Instead of drop tanks or cross feed, why not just make it a little wider?  Instead of the current 1.7M width, they can make it 2m or there abouts. A little extra width will pick-up a lot of extra fuel carring capacity. 

Tooling for wider diameter tankage is expensive.

They already own tooling for 3.66 meter tankage ;)
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