"Used" Dragons

[clongton]

Read a quote from Elon saying Dragon 2 will be not have solar panels at all. Can't find it now.

I remember something about the crewed Dragon not having solar panels. If there is a cargo version of Dragon2 (which I personally find plausible), then it might still have solar panels.

Unlikely. See above:

But for the record, here is possibly the most well-known source: a quote from Shotwell transcripted by manboy from here: http://archive.thespaceshow.com/shows/2212-BWB-2014-03-21.mp3 :

"When will the cargo version of Dragon begin making propulsive landings?" "So the current version of Dragon lands in water on parachute descent, we are looking at landing it on land under parachute. As for propulsive landing that is for our new version, we call it V2 for Dragon and that's the primary vehicle, that's the vehicle for crew, and we will retrofit that for cargo."

Per Shotwell, Cargo Dragon will be backfitted from Crew Dragon.

[Elmar Moelzer]

But for the record, here is possibly the most well-known source: a quote from Shotwell transcripted by manboy from here: http://archive.thespaceshow.com/shows/2212-BWB-2014-03-21.mp3 :

"When will the cargo version of Dragon begin making propulsive landings?" "So the current version of Dragon lands in water on parachute descent, we are looking at landing it on land under parachute. As for propulsive landing that is for our new version, we call it V2 for Dragon and that's the primary vehicle, that's the vehicle for crew, and we will retrofit that for cargo."

Per Shotwell, Cargo Dragon will be backfitted from Crew Dragon.

And that contradicts what I said exactly how? You think that a crew Dragon that has been retrofitted for cargo cant have trunk with solar panels? I am confused.

[llanitedave]

I think the Dragon and the trunk should be considered two separate entities.

[baldusi]

Does anyone know if the trunk is large enough to house a VF-200 VASIMR rocket, or a modified one?

Current Dragon supplies about 3kW of power to payload. VF-200 requires 200kW.

[swervin]

Does anyone know if the trunk is large enough to house a VF-200 VASIMR rocket, or a modified one?

Current Dragon supplies about 3kW of power to payload. VF-200 requires 200kW.

For sure! ...and thanks for following up with me. My understanding was that the possible test when/if flown to the ISS would utilize battery packs to provide power during tests vs only relying on the solar panels.

Not sure how large a battery pack that may be, if that method is to be used, but perhaps the internal volume of Dragon could be packed with batteries?

Also, would VASIMR physically FIT in the trunk?

All questions we may not know, but I'm a fan of finding different uses and re-uses of existing hardware to advance technology!

Cheers,
Splinter

[Jim]

I think the Dragon and the trunk should be considered two separate entities.

No, it shouldn't.  Dragon has limited capabilities (mission life) once it sheds the trunk.

[Lar]

Does anyone know if the trunk is large enough to house a VF-200 VASIMR rocket, or a modified one?

Current Dragon supplies about 3kW of power to payload. VF-200 requires 200kW.

For sure! ...and thanks for following up with me. My understanding was that the possible test when/if flown to the ISS would utilize battery packs to provide power during tests vs only relying on the solar panels.

Not sure how large a battery pack that may be, if that method is to be used, but perhaps the internal volume of Dragon could be packed with batteries?

I'm not clear on how batteries can take you from 3 Kw to 200 Kw. You might want to try running some numbers but my gut tells me that would be much of the usable mass of the vehicle.

[kirghizstan]

Does anyone know if the trunk is large enough to house a VF-200 VASIMR rocket, or a modified one?

Current Dragon supplies about 3kW of power to payload. VF-200 requires 200kW.

For sure! ...and thanks for following up with me. My understanding was that the possible test when/if flown to the ISS would utilize battery packs to provide power during tests vs only relying on the solar panels.

Not sure how large a battery pack that may be, if that method is to be used, but perhaps the internal volume of Dragon could be packed with batteries?

Also, would VASIMR physically FIT in the trunk?

All questions we may not know, but I'm a fan of finding different uses and re-uses of existing hardware to advance technology!

Cheers,
Splinter

i'm not clear on if you are asking if it would fit in the trunk but do the testing with power form ISS or if you are suggesting using Dragon's power?

i'm also not clear on how this relates to used Dragons

[Avron]

I think the Dragon and the trunk should be considered two separate entities.

No, it shouldn't.  Dragon has limited capabilities (mission life) once it sheds the trunk.

Why.. if they go to batteries, the trunk is just a trunk, ?

[docmordrid]

IIRC  crew Dragon gets extra batteries, which are in the trunk. Jettison the trunk and you lose that reserve.

[ey]

It might still be feasible. A Tesla Model S uses a 310 kW motor and has a 60 kWh battery. At 200 kW that should last for the 15 minute burst planned for the ISS test. Though that's ~1000 pounds of batteries in addition to the mass of the VF-200 which is 620 kg (1300 pounds).

This link may help get an idea about the size of the VF-200: http://www.adastrarocket.com/aarc/VF-200

[swervin]

i'm also not clear on how this relates to used Dragons

That's valid, however, what do any of us really know about what 'relates' to used Dragons? So far as I can tell the known thing about them, is that they exist. I assume we all wonder if/when they will be reused at some point, and in what manner. I'm simply exploring one idea/possibility, not asserting I understand how or if they will be re-used.

It might still be feasible. A Tesla Model S uses a 310 kW motor and has a 60 kWh battery. At 200 kW that should last for the 15 minute burst planned for the ISS test. Though that's ~1000 pounds of batteries in addition to the mass of the VF-200 which is 620 kg (1300 pounds).

This link may help get an idea about the size of the VF-200: http://www.adastrarocket.com/aarc/VF-200

Interesting! I didn't realize that info about the Tesla Model S! Thanks for the link!

I think you understand what I'm getting at though. Basically, place batteries inside Dragon to power a notional VASIMR engine for short duration bursts, much as is planned on the ISS. Given the drastic difference in mass between the ISS and a Dragon, any idea how much those bursts could accelerate a Dragon? (I'm not qualified to run those numbers any longer... orbital mechanics classes were too long ago for me to remember...)   

Even at let's say 1500lbs for batteries + 1500lbs for a VF-200 sized engine, that is still within the F9 v1.1's up-mass capes, right? Didn't it just take up more than that to the ISS on the last mission?

If you all want this theoretical discussion to end, no harm no foul, but it seems the topic is worthy of a thought, to me. .... those Dragons should be re-used for something which might further spaceflight!

Splinter

[Jim]

The trunk also supplies more than just power, it has radiators.

[TrevorMonty]

The plan is to fit VASIMR engines to ISS and power them from a 50kwhr battery to enable 15 min bursts at full thrust.

Using Dragon as free flying test platform with a 60kwhr battery should be able to achieve same result. Allow 24 HR between tests for batteries to recharge. They could even send it around the moon.

[swervin]

The plan is to fit VASIMR engines to ISS and power them from a 50kwhr battery to enable 15 min bursts at full thrust.

Using Dragon as free flying test platform with a 60kwhr battery should be able to achieve same result. Allow 24 HR between tests for batteries to recharge. They could even send it around the moon.

I was thinking precisely that, Trevor. Sounds like a great technology demonstration platform to me. Would daily 15min firings (or maybe twice daily if you had enough room/capacity for two battery buses) provide much increase in thrust or would such short VF-200 firings be similar to an ion engine running continuously? (big picture?)

Why stop at the moon?

Splinter

[dror]

The plan is to fit VASIMR engines to ISS and power them from a 50kwhr battery to enable 15 min bursts at full thrust.

Using Dragon as free flying test platform with a 60kwhr battery should be able to achieve same result. Allow 24 HR between tests for batteries to recharge. They could even send it around the moon.

Why is that any better than using a light weight 3kw constant acceleration engine?

[Llian Rhydderch]

The plan is to fit VASIMR engines to ISS and power them from a 50kwhr battery to enable 15 min bursts at full thrust.

Using Dragon as free flying test platform with a 60kwhr battery should be able to achieve same result. Allow 24 HR between tests for batteries to recharge. They could even send it around the moon.

I was thinking precisely that, Trevor. Sounds like a great technology demonstration platform to me. Would daily 15min firings (or maybe twice daily if you had enough room/capacity for two battery buses) provide much increase in thrust or would such short VF-200 firings be similar to an ion engine running continuously? (big picture?)

Why stop at the moon?

Splinter

I would suspect that the main factor here is who is paying for the demonstration mission?

My guess is that NASA is paying for lofting the VASIMR VF-200 to space, and possibly for the twin 100 kW engines to be built in the first place.  In other words, Ad Astra is likely getting this flight test for a very low pecuniary price.

On the other hand, flying to space to do the demo with a "used Dragon" plus trunk plus VF-200 plus Tesla-sized large battery pack would need to be funded by someone.  If it were a commercial transaction, the ordinary way would be for the company developing the technology (Ad Astra) to pay the cargo transport and mission hardware supplier (SpaceX) for the launch and the satellite.  Even at SpaceX everyday low prices, with a used-price Dragon, this is an $80 or $100 million dollar mission. 

Thus, I think we won't see a VF-200 tested on a Used Dragon anytime real soon, but for economic reasons.

Now, if a philanthropic gabillionaire wanted to put a VASIMR-based moon cycler in LEO, and fly out to the moon or asteroids with a DragonLab space probe, cool.  Bring it on.   

[swervin]

The plan is to fit VASIMR engines to ISS and power them from a 50kwhr battery to enable 15 min bursts at full thrust.

Using Dragon as free flying test platform with a 60kwhr battery should be able to achieve same result. Allow 24 HR between tests for batteries to recharge. They could even send it around the moon.

Why is that any better than using a light weight 3kw constant acceleration engine?

Dror, I don't think anyone is arguing it is better. The idea of a VASIMR engine in a trunk was a way to put to use, or more like re-use, a Dragon spacecraft. The thought when I asked the question was, and still remains, reusing a  Dragon as a platform to further an unproven (in space) technology.

As stated above, unlikely to happen for understandable reasons. We may have beaten the idea to death... :-)

Splinter

[guckyfan]

The plan is to fit VASIMR engines to ISS and power them from a 50kwhr battery to enable 15 min bursts at full thrust.

Using Dragon as free flying test platform with a 60kwhr battery should be able to achieve same result. Allow 24 HR between tests for batteries to recharge. They could even send it around the moon.

Why is that any better than using a light weight 3kw constant acceleration engine?

Because the purpose would be testing VASIMR, not accelerating Dragon.

[fatjohn1408]

It's funny how, when SpaceX opts for mass production instead of reusability, a lot of people start to tout the benefits of mass production. Streamlining the process, enhancing the design iteratively, etc...