SpaceX Dragon 2 Updates and Discussion - Thread 3

[oldAtlas_Eguy]

One of the reasons for the 7 seat design was for the economics for commercial HSF. It costs the same to develop and launch a 4 seater as it does a 7 seater. This makes the commercial price per seat for a commercial buyer at 50% than the NASA prices. Pilot + 6 passengers vs pilot and 3 passengers. This applies for all of the proposed CC systems Dragoon 2, Starliner, Shepard, and Dream Chaser. Which is why they all went for a design goal for 7 persons due to the space available on a volume and weight optimized systems on the available launchers.

But NASA never needed more than 4 seats (initially only 3 with option to grow to 4 based on max personnel support levels that ISS can handle). But having a capability of 7 can offer options for NASA in the future. In a world of commercial Space Station replacement of ISS that is not restricted to just 7 max occupants that ability of supporting transport of 7 at a time will be very usefull and result in significant cost savings in operating a 2X larger space station for same operations costs.

Dragon's size is dictated by its multipurpose role and cost optimization.

Cargo is bulkier than Crew, and Dragon is already volume-limited for Cargo. There is no cost savings to building and operating a smaller 4-person Crew vehicle when you have to have a large Cargo vehicle with 95% of the same abilities anyway.

Any consideration for the commercial market are secondary at best, as that market is purely speculative.

Although this may be true for Dragon 2, but what about all the other entrants into the CC program that also had max crew sizes of 7?  This sizing is more a result of LV than anything else. With F9 and the Atlas V of similar size using same sized crewed vehicles shows one for one competitive tradeoffs. Different sized vehicles confuses the competition space in this CC program and the other entrants avoided the complication. Being that part of the tradespace that each entrant had to meet in the CC program they had to show how their vehicle had applicability to a possible commercial HSF market. One of those is more crew per flight results in lower per seat price.

[jbenton]

One of the reasons for the 7 seat design was for the economics for commercial HSF. It costs the same to develop and launch a 4 seater as it does a 7 seater. This makes the commercial price per seat for a commercial buyer at 50% than the NASA prices. Pilot + 6 passengers vs pilot and 3 passengers. This applies for all of the proposed CC systems Dragoon 2, Starliner, Shepard, and Dream Chaser. Which is why they all went for a design goal for 7 persons due to the space available on a volume and weight optimized systems on the available launchers.

But NASA never needed more than 4 seats (initially only 3 with option to grow to 4 based on max personnel support levels that ISS can handle). But having a capability of 7 can offer options for NASA in the future. In a world of commercial Space Station replacement of ISS that is not restricted to just 7 max occupants that ability of supporting transport of 7 at a time will be very usefull and result in significant cost savings in operating a 2X larger space station for same operations costs.

this is Lori G. at work ... its the airmail contract ...well a percentage of it...

I was under the impression that - at least at the beginning of the program - they only intended to have 4 'naughts go up at once, but they still wanted 7 seats. NASA requires having as much evacuation capacity as there are crew members. 3 seats in each of 2 Soyuz's is good for 6 long duration crew; 4 on a USCCV + 3 on a Soyuz is good for 7 long duration crew. However, if the USCCV can seat 7, then they can evacuate the whole crew on one vehicle if that is ever necessary. Not strictly required, but nice to have?

Didn't X-38 have accommodations for 7?

[HVACMan]

Correction, it seems it could use the Draco thrusters, not cold gas thrusters to fine tune the landing so that it could hit the landing pad.

[joek]

I was under the impression that - at least at the beginning of the program - they only intended to have 4 'naughts go up at once, but they still wanted 7 seats. NASA requires having as much evacuation capacity as there are crew members. 3 seats in each of 2 Soyuz's is good for 6 long duration crew; 4 on a USCCV + 3 on a Soyuz is good for 7 long duration crew. However, if the USCCV can seat 7, then they can evacuate the whole crew on one vehicle if that is ever necessary. Not strictly required, but nice to have?

NASA requirement since the beginning has been 4 up and 4 down (plus some cargo) and 4 safe haven; no requirement for emergency evacuation of more than 4..

See CCT-REQ-1130 (requirements) and CCT-DRM-1110 (DRM descriptions), available here.  Those are from 2011 (the latest public drafts at the time they were posted).

CCT-DRM-1110 includes a description of a "Commercial Space Station Design Reference Mission" but no statement as to capacity.  That and the satellite servicing DRM also described in CCT-DRM-1110 were always notional and never a NASA requirement.

[su27k]

I have always assumed SpaceX and Boeing chose the magic number 7 because that's the crew compliment for the Shuttle. It would be kind of embarrassing if your new spaceships couldn't match the capability of the old one.

[Herb Schaltegger]

Didn't X-38 have accommodations for 7?

Initial concepts for what was then known as the ACRV (Assured Crew Return Vehicle) during Space Station Freedom were baselined for 4 each, with one to be stationed on-orbit as of the PMC milestone (Permanently-Manned Capability) and two by AC (Assembly Complete). But ACRV itself never progressed much beyond early MacPaint diagrams of a generic capsule shape on SSF topology maps. X-38 sort of glommed onto the possible role as a crew return vehicle somewhere along the way instead but again, crew capacity and accommodation designs never firmed up all that much to my knowledge.

[woods170]

Didn't X-38 have accommodations for 7?

Initial concepts for what was then known as the ACRV (Assured Crew Return Vehicle) during Space Station Freedom were baselined for 4 each, with one to be stationed on-orbit as of the PMC milestone (Permanently-Manned Capability) and two by AC (Assembly Complete). But ACRV itself never progressed much beyond early MacPaint diagrams of a generic capsule shape on SSF topology maps. X-38 sort of glommed onto the possible role as a crew return vehicle somewhere along the way instead but again, crew capacity and accommodation designs never firmed up all that much to my knowledge.

X-38 V201, which was the full-scale orbital prototype of the CRV was well over 80% complete when the X-38/CRV program was cancelled. The orbital prototype was a intended for (un)docking- and return-from-orbit tests.
Crew capacity was definitively established. Crew accommodation design was in an advanced state, by the time the program was canned.

The reason there is little info on the US-side about crew accommodations is because those were the responsibility of ESA.

ESA was responsible for:
- vehicle    shape    validation    and    overall
aerodynamic     and     aerothermodynamic
database;
- crew cabin design and layout;
–  aft  fuselage  design  and  manufacture  of
major aft structure elements;
–  rudders, including accompanying sensors;
–  the metal nose structure;
–  the front and main landing gear;
–  the cabin equipment pallets;
–  hot  structure  (Ceramic  Matrix  Composite,
CMC)  leading  edge  segments  of  the  fixed
fin, including accompanying sensors;
–  the   Thermal   Protection   System   (TPS)
blankets  for  the  leeward  vehicle  surfaces,
including fins and aft fuselage frame;
–  guidance,  navigation  and  control  (GNC)
software, including man/machine interfaces,
for the parafoil flight phase;
–  Fault  Tolerant  Computers  with  reentry  GNC
software;
–  Vehicle Analysis and Data Recording System
(VADRS),  including  front-end  electronics  for
overall vehicle instrumentation;
–  (pre)development  of  the  CRV/ISS  berthing/
docking mechanism;
–  active thermal control water pump;
–  crew seat concept for the CRV and provision
of    a    representative    crew    seat    with
instrumented dummy for X-38 flight testing.

And yes, X-38/CRV was established to have a maximum crew capacity of 7 astronauts.

Additional reading: https://web.archive.org/web/20061003155409/http://esapub.esrin.esa.it/bulletin/bullet101/graf.pdf

[cscott]

Not sure about its accuracy, but a redditor claimed the Crew Dragon UI is done in Chromium and WebGL.

I'd love to know more details. I worked on a very early JavaScript+OpenGL system at litl.com back in 2009, and worked on WebGL support for the OLPC next generation tablet 2011-2013.  At the time (five years ago, perhaps an eternity in hardware) it was very difficult to get robust OpenGL support on chipsets from vendors.  For tablet-grade systems, they tended to test on Android and that's it; any OpenGL features not required by Android were almost certain not to work properly.

For Chromium+WebGL I'd guess the best SoC chipset support is probably for something like Chromebooks.  I'd be surprised if those chipsets were up to the Dragon UX task.

Very curious how they found a commodity embedded (high performance?) processor with solid (tested) vendor support for WebGL.  Maybe the landscape has changed, and probably things are different when you're talking Nvidia/amd64 instead of the more typical embedded SoCs (arm in particular).

Assuming they can get the framerate and reliability issues settled with the vendor, and have a reasonable solution to managing GC in their framework, JavaScript and OpenGL (and the WebGL flavor of it) can be a quite pleasant development environment.  Pretty future-proof as well (esp if they are using amd64 hardware), since JavaScript keeps getting faster via competition in the ecosystem; you should be able to continue to port that codebase to new substrates for a decade at least.

[Lars-J]

Didn't X-38 have accommodations for 7?

Initial concepts for what was then known as the ACRV (Assured Crew Return Vehicle) during Space Station Freedom were baselined for 4 each, with one to be stationed on-orbit as of the PMC milestone (Permanently-Manned Capability) and two by AC (Assembly Complete). But ACRV itself never progressed much beyond early MacPaint diagrams of a generic capsule shape on SSF topology maps. X-38 sort of glommed onto the possible role as a crew return vehicle somewhere along the way instead but again, crew capacity and accommodation designs never firmed up all that much to my knowledge.

X-38 V201, which was the full-scale orbital prototype of the CRV was well over 80% complete when the X-38/CRV program was cancelled. The orbital prototype was a intended for (un)docking- and return-from-orbit tests.
Crew capacity was definitively established. Crew accommodation design was in an advanced state, by the time the program was canned.

[snip]

And yes, X-38/CRV was established to have a maximum crew capacity of 7 astronauts.

Additional reading: https://web.archive.org/web/20061003155409/http://esapub.esrin.esa.it/bulletin/bullet101/graf.pdf

Wow, 7 in the X-38? Now *that* would have been tight as "spam in a can", unless my recollection about the X-38 size is wrong.

[EDIT] Added a picture from the PDF. My recollection was right. 7 in that space!

[docmordrid]

>
Wow, 7 in the X-38? Now *that* would have been tight as "spam in a can", unless my recollection about the X-38 size is wrong.

Wiki sez 30 feet, about the same size as Dream Chaser. In its HL-20 life Dream Chaser  was rated for 8 (Lockheed) to 10 (Rockwell.)

http://www.cs.odu.edu/~mln/ltrs-pdfs/NASA-93-tm4453.pdf

[Lars-J]

>
Wow, 7 in the X-38? Now *that* would have been tight as "spam in a can", unless my recollection about the X-38 size is wrong.

Wiki sez 30 feet, about the same size as Dream Chaser. In its HL-20 life Dream Chaser  was rated for 8 (Lockheed) to 10 (Rockwell.)

http://www.cs.odu.edu/~mln/ltrs-pdfs/NASA-93-tm4453.pdf

Yes but it is cabin size that matters. Some shapes - like HL20/Dreamchaser has a taller cabin that allows passengers to sit upright. Capsules are even more volume efficient. But contrast this with the image in my post, showing how much space just *one* person lying down would affect the cabin volume.

[TripleSeven]

One of the reasons for the 7 seat design was for the economics for commercial HSF. It costs the same to develop and launch a 4 seater as it does a 7 seater. This makes the commercial price per seat for a commercial buyer at 50% than the NASA prices. Pilot + 6 passengers vs pilot and 3 passengers. This applies for all of the proposed CC systems Dragoon 2, Starliner, Shepard, and Dream Chaser. Which is why they all went for a design goal for 7 persons due to the space available on a volume and weight optimized systems on the available launchers.

But NASA never needed more than 4 seats (initially only 3 with option to grow to 4 based on max personnel support levels that ISS can handle). But having a capability of 7 can offer options for NASA in the future. In a world of commercial Space Station replacement of ISS that is not restricted to just 7 max occupants that ability of supporting transport of 7 at a time will be very usefull and result in significant cost savings in operating a 2X larger space station for same operations costs.

this is Lori G. at work ... its the airmail contract ...well a percentage of it...

I was under the impression that - at least at the beginning of the program - they only intended to have 4 'naughts go up at once, but they still wanted 7 seats. NASA requires having as much evacuation capacity as there are crew members. 3 seats in each of 2 Soyuz's is good for 6 long duration crew; 4 on a USCCV + 3 on a Soyuz is good for 7 long duration crew. However, if the USCCV can seat 7, then they can evacuate the whole crew on one vehicle if that is ever necessary. Not strictly required, but nice to have?

Didn't X-38 have accommodations for 7?

Lori Garver and I have had a few back and ups even in her current spot with ALPA...but really she has the heart of a space geek ...and wants a space future

she is the one who made sure that there were spare seats on the commercial crew...for the folks who built the capsules to sell.  she understands the airmail contract...and what it launched

[gongora]

Any kind of realistic tourist itinerary on a Commercial Crew flight would either require flying the same type of capsule twice in a row so one company could do it, or SpaceX and Boeing would need to cooperate and have the tourist go up on one capsule and come down on the other kind.

[Coastal Ron]

Any kind of realistic tourist itinerary on a Commercial Crew flight would either require flying the same type of capsule twice in a row so one company could do it, or SpaceX and Boeing would need to cooperate and have the tourist go up on one capsule and come down on the other kind.

NASA controls who flies on Commercial Crew flights since they are NASA paid seats, and NASA's plan with having four seats on Commercial Crew was to allow them to increase the amount of science they can do by adding a person who does not need to do part time station support and maintenance.

So I don't see a mechanism for getting a seat on the government-funded Commercial Crew flights - not unless the U.S. Government wants to send someone up to generate goodwill (i.e. like many people did on the Shuttle). But that would not be a "tourist", it would be a government guest.

If the ISS is truly going to end it's mission at the end of 2024, I would think NASA would fight hard to fill each available seat with mission specialists that can help NASA get as much science out of the ISS as possible.

[Roy_H]

Any kind of realistic tourist itinerary on a Commercial Crew flight would either require flying the same type of capsule twice in a row so one company could do it, or SpaceX and Boeing would need to cooperate and have the tourist go up on one capsule and come down on the other kind.

First of all, no special cooperation required. NASA would make the decision if it wants to fly tourists. You are right, tourists would not stay for 6 months, so the only reasonable way is up on one, down on the other. This has the added complication of requiring both a SpaceX and Boeing flight suit (and I believe these are custom made to fit). Highly unlikely this will happen.

[jbenton]

Any kind of realistic tourist itinerary on a Commercial Crew flight would either require flying the same type of capsule twice in a row so one company could do it, or SpaceX and Boeing would need to cooperate and have the tourist go up on one capsule and come down on the other kind.

First of all, no special cooperation required. NASA would make the decision if it wants to fly tourists. You are right, tourists would not stay for 6 months, so the only reasonable way is up on one, down on the other. This has the added complication of requiring both a SpaceX and Boeing flight suit (and I believe these are custom made to fit). Highly unlikely this will happen.

If the tourists in question are 4 independently wealthy billionaires willing to spend a quarter of what Denis Tito spent ($200 million) - or 7 of them to spend a seventh of that - they could just deal with SpaceX or Boeing directly (with NASA permission) and buy at fortnight in space "on station" that's about how long shuttle missions to the ISS were. Provided that the only cargo craft (HTV, Cygnus, etc.) attached to the ISS are berthing rather than docking, there would be one docking port open (alternatively, a Dragon or a HTV could just bring another up)

This way, it would be the same ship up and down.

[Coastal Ron]

Any kind of realistic tourist itinerary on a Commercial Crew flight would either require flying the same type of capsule twice in a row so one company could do it, or SpaceX and Boeing would need to cooperate and have the tourist go up on one capsule and come down on the other kind.

First of all, no special cooperation required. NASA would make the decision if it wants to fly tourists. You are right, tourists would not stay for 6 months, so the only reasonable way is up on one, down on the other. This has the added complication of requiring both a SpaceX and Boeing flight suit (and I believe these are custom made to fit). Highly unlikely this will happen.

NASA doesn't do "tourism". Russia did it for money, the U.S. Government doesn't have such concerns.

Plus the actual cost of sending a private citizen up, where the U.S. Government can't give away services, would likely be too much for anyone to buy.

Besides, NASA is focused on doing science on the ISS, and the 4th seat will allow them to effectively double their science output. Who at NASA is going to reduce their science output to send up a tourist?

[gongora]

We weren't talking about replacing a NASA astronaut, but adding a fifth seat in the supposedly seven seat capable capsules.  (I think Boeing is still claiming this to be possible.)  I think the details of doing it on a NASA mission make it unlikely.

[joek]

Remember, both chosen CCP providers offered to NASA solutions that could in fact do more than NASA requirements demanded. The "evacuate the entire ISS crew" option was such an extra, offered by both Boeing and SpaceX.

Getting a bit far afield here, but...

Also remember that any bonus points based on those "extra" capabilities in the evaluation and award process ended with CCDev2 (last SAA).  With CCiCap (and move to FAR) capabilities beyond NASA's specific requirements could not be considered in the evaluation and award process, nor could providers be held to any other requirements (see CCT-REQ-1130).

Given the trials and tribulations of the program meeting basic requirements, I would not be surprised if the originally envisioned seven-seat capability was demoted to maybe-aspirational some time ago.

[oiorionsbelt]

First of all, no special cooperation required. NASA would make the decision if it wants to fly tourists. You are right, tourists would not stay for 6 months, so the only reasonable way is up on one, down on the other. This has the added complication of requiring both a SpaceX and Boeing flight suit (and I believe these are custom made to fit). Highly unlikely this will happen.

Unlikely for sure but wouldn't it be great to read the reviews?