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Posted (edited)

Would Falcon Heavy need to go partially or even fully expendable to get Dragon XL to TLI?

Edited by RealKerbal3x
missed a word

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Probably partially expendable. The reusable payload to GTO is only about 8 tonnes, and not only is TLI more difficult than that but dragon plus 5 tonnes is about 17 tonnes. The fully expendable payload to TLI is probably in the region 20-21 tonnes.

With the reusable side boosters being only about 10% payload penalty it really doesn't make sense to expend them if you can avoid it.

 

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Looks like the depiction has the same docking port (with four Draco RCS thrusters) as Dragon 2.

There's probably a 75% chance this has the same exact propellant tanks as Dragon 2, just with the aeroshell and heat shield and chutes removed. Might be useful for estimates.....

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6 hours ago, RCgothic said:

Probably partially expendable. The reusable payload to GTO is only about 8 tonnes, and not only is TLI more difficult than that but dragon plus 5 tonnes is about 17 tonnes. The fully expendable payload to TLI is probably in the region 20-21 tonnes.

With the reusable side boosters being only about 10% payload penalty it really doesn't make sense to expend them if you can avoid it.

 

yeap, i was thinking too at a " side booster barge landing, centre core expended" configuration

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We don't know whether that 5-tonne payload is limited by injection dV (FHUS) or insertion dV (vehicle).

Let's start with the assumption that the 5-tonne payload is limited by the insertion dV. It takes 430 m/s to go from TLI to the gateway...let's pump that up to 500 m/s for margin, rendezvous, docking, and so forth. Dracos develop 300 s of specific impulse. The Dragon XL would need to burn 15.6% of its mass as propellant to generate 500 m/s, and the Dragon 2's propulsion package has 1388 kg of propellant, so that's a total vehicle wet mass of 8.9 tonnes. With 5 tonnes being payload and 1.38 tonnes being propellant, that leaves a vehicle dry mass of 2.51 tonnes.

Dragon 2 has a dry mass of 9.53 tonnes. Does that mean ECLSS+heat shield+aeroshell+ballistic sled+parachutes total a whopping 7 tonnes? Or are we looking at a vehicle with higher propellant capacity?

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19 hours ago, sh1pman said:

It may have a disposable nose cone (Dragon 1 style) and no fairing. 

From spaceflightnow article:

"Unlike the Dragon 2, which flies without an aerodynamic shroud on top of SpaceX’s Falcon 9 rocket, the Dragon XL will lift off inside a payload fairing on the company’s bigger Falcon Heavy launcher, according to Dan Hartman, NASA’s Gateway program manager at the Johnson Space Center in Houston."

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From the render it looks like it's mounted backwards on stage 2.

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9 minutes ago, RealKerbal3x said:

From the render it looks like it's mounted backwards on stage 2.

I don't think it will be though.

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10 minutes ago, Flying dutchman said:

Any updates on ss/sh?

Since when?

The most recent news is that they are about to move SN3's fuel tank onto its transporter for transport to the launch pad, testing and potentially short hops. Parts for SN4 are also being made.

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3 hours ago, Wjolcz said:
3 hours ago, RealKerbal3x said:

From the render it looks like it's mounted backwards on stage 2.

I don't think it will be though.

I think it will. Single payload adapter/docking ring/propulsion unit.

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4 minutes ago, sevenperforce said:

I think it will. Single payload adapter/docking ring/propulsion unit.

It certainly simplifies things under the fairing, and leaves the possibility of a "trunk" for larger cargo.

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1 hour ago, tater said:

It certainly simplifies things under the fairing, and leaves the possibility of a "trunk" for larger cargo.

Or leaving the interior empty and manifesting a 5 tonne module externally.

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Posted (edited)

Ok, so it seems I was wrong. It just seemed very unorthodox to do things this way. The question now is: why won't more spacecraft be built this way? Cygnus probably could be. I guess it all depends on manufacturing techniques.

Btw, the Starship crawler is crawling.

 

Edited by Wjolcz

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Sn3 is being lifted onto the "crawler" as of right now

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11 hours ago, Wjolcz said:

Ok, so it seems I was wrong. It just seemed very unorthodox to do things this way. The question now is: why won't more spacecraft be built this way? Cygnus probably could be. I guess it all depends on manufacturing techniques.

Btw, the Starship crawler is crawling.

 

Anything with a heat shield, need to protect that heat shield more than the docking ring, and generally the docking ring needs to be in the opposite side.

For disposable cargo I don't know, perhaps it's just design habit.

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This is not the most on topic, but I remember Elon saying at one point that no two Falcon 9s were the same (up until Block 5 anyway). Does anyone have the source for this? Its for a speech for school.

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2 hours ago, Ultimate Steve said:

This is not the most on topic, but I remember Elon saying at one point that no two Falcon 9s were the same (up until Block 5 anyway). Does anyone have the source for this? Its for a speech for school.

He said it on twitter, but you will have to dig a lot  to find it, it's  at least a 2 years old statement

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You can see the swing out legs.

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Multicoloured cranes! RGB cherry pickers and a yellow hook crane! Nice.

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