Sierra Space Dream Chaser DISCUSSION Thread (was SNC)

[catdlr]

That may well be. I don't think we know that yet and we may never know. Boeing did not self-impose this requirement on Starliner and SpaceX did not self-impose it on Dragon. If I recall correctly, in each of those cases they planned to perform initial tests of the system well away from ISS, and then attempt docking to ISS on the same flight.

Boeing did end up doing a free-flier test, but not on purpose.

Dragon and Starliner used systems with flight heritage, unlike Sierra. The only way to provide/create the data to allow for certification may have to be a flight.

Emphasis mine.

Although some of the RCS systems and propulsion systems flown on Starliner have flight heritage, the "clustered-inside-a-doghouse" configuration had no flight heritage. Combined with insufficient modeling of the thermal "climate" inside and around the "doghouse", this resulted in Starliner suffering from (RCS) thrusters going offline (due to thermal limits) on all three flown Starliner missions.

Have RCS "dog house covers" ever been used in heritage space vehicles? It seems that spacecraft like Apollo had visible RCS thrusters located on the outside, which were both functional and visible. In contrast, modern vehicle designs often conceal RCS systems for aesthetic reasons, prioritizing style and sleekness. As a result, RCS has shifted from being a functional out-in-the-open component to a stylistic element, at least in the case of Starliner and Dragon.  But maybe that "Style" choice, for Boeing, is working against them.

[DanClemmensen]

That may well be. I don't think we know that yet and we may never know. Boeing did not self-impose this requirement on Starliner and SpaceX did not self-impose it on Dragon. If I recall correctly, in each of those cases they planned to perform initial tests of the system well away from ISS, and then attempt docking to ISS on the same flight.

Boeing did end up doing a free-flier test, but not on purpose.

Dragon and Starliner used systems with flight heritage, unlike Sierra. The only way to provide/create the data to allow for certification may have to be a flight.

Emphasis mine.

Although some of the RCS systems and propulsion systems flown on Starliner have flight heritage, the "clustered-inside-a-doghouse" configuration had no flight heritage. Combined with insufficient modeling of the thermal "climate" inside and around the "doghouse", this resulted in Starliner suffering from (RCS) thrusters going offline (due to thermal limits) on all three flown Starliner missions.

Have RCS "dog house covers" ever been used in heritage space vehicles? It seems that spacecraft like Apollo had visible RCS thrusters located on the outside, which were both functional and visible. In contrast, modern vehicle designs often conceal RCS systems for aesthetic reasons, prioritizing style and sleekness. As a result, RCS has shifted from being a functional out-in-the-open component to a stylistic element, at least in the case of Starliner and Dragon.  But maybe that "Style" choice, for Boeing, is working against them.

Dragon 2 mounts it's thrusters internally because they are explicitly on the capsule, not the trunk, so they are recovered and reused instead of being discarded. The capsule must be "sleek and stylish" because it must survive re-entry. the design drives down the cost of the trunk to the extent possible. By contrast, the Starliner's expended service module, with lots of thrusters, etc., is expensive. In this regard Dream Chaser is more like Dragon 2.

[laszlo]

Have RCS "dog house covers" ever been used in heritage space vehicles? ...

The RCS covers on the Gemini spacecraft look like at least doggie beds, if not full dog houses to me.

[Jim]

Have RCS "dog house covers" ever been used in heritage space vehicles? It seems that spacecraft like Apollo had visible RCS thrusters located on the outside, which were both functional and visible. In contrast, modern vehicle designs often conceal RCS systems for aesthetic reasons, prioritizing style and sleekness. As a result, RCS has shifted from being a functional out-in-the-open component to a stylistic element, at least in the case of Starliner and Dragon.  But maybe that "Style" choice, for Boeing, is working against them.

It is done for aerodynamic reasons.  Boeing just didn't do their home work.

[abaddon]

In this regard Dream Chaser is more like Dragon 2.

IIRC at least some of Dream Chaser's thrusters are on the discarded service module, which is more like Starliner.  I don't recall offhand which thrusters and how much if any the returned spaceplan has.

Dragon's equivalent, I suppose, would be the new reboost thrusters that are located in the trunk.

[DanClemmensen]

In this regard Dream Chaser is more like Dragon 2.

IIRC at least some of Dream Chaser's thrusters are on the discarded service module, which is more like Starliner.  I don't recall offhand which thrusters and how much if any the returned spaceplan has.

Dragon's equivalent, I suppose, would be the new reboost thrusters that are located in the trunk.

The boost kit much more like a payload. It is carried to provide a service to another spacecraft in orbit. It is not used for thrust for the Dragon itself and Dragon has flown 31 missions without it. Also the boost kit does not appear to be space-constrained at all, to put it mildly.

[abaddon]

In this regard Dream Chaser is more like Dragon 2.

IIRC at least some of Dream Chaser's thrusters are on the discarded service module, which is more like Starliner.  I don't recall offhand which thrusters and how much if any the returned spaceplan has.

Dragon's equivalent, I suppose, would be the new reboost thrusters that are located in the trunk.

The boost kit much more like a payload. It is carried to provide a service to another spacecraft in orbit. It is not used for thrust for the Dragon itself and Dragon has flown 31 missions without it. Also the boost kit does not appear to be space-constrained at all, to put it mildly.

I probably shouldn't have mentioned it at all, honestly.  It's not really relevant.  Was just trying to make the point that Dragon has all its thrusters on the capsule, with the only exception being the boost kit (which as you note isn't really the same thing).

[vt_hokie]

I'm holding out hope that the vehicle makes it to orbit in some fashion, but if not, I hope we get to see the vehicle in a museum someday. I'm not sure what happened to, say, X-33's hardware (hopefully it didn't just get sent to a landfill) but since this is more or less a completed vehicle, I sure hope it has a better future than that one did.

When Sierra Space was spun off by SNC to become a standalone company, was that SNC's way of saying we're not subsidizing this effort with our more profitable lines of business?

[Comga]

It seems like the system that is delaying her is the system that was supposed to give her the greatest flexibility and be one of her strengths, the non-toxic propulsion system allowing it to land at any airport without possibly creating a toxic/hazardous environment.

So when you blow past your IOC date (2021?) and you get NASA's opinions and you see Starliner's troubles, you buy an Electron launch or a spot on a Transporter and put up a satellite or just a payload to prove out the thrusters on orbit.
"Hindsight is 20/20" but the job of management is to foresee issues and plan preemptively.
(On the other hand, seeing NASA's what-me-worry? reaction to the Starliner screw-ups, perhaps  it seemed logical to just hope for the best. )

[JAFO]

I was in Denver and took time to stop at the Wings Over the Rockies Museum, where they have the HL-20 mockup on display.

I was also surprised to see the old Craig Breedlove/Steve Fossett Sonic Arrow tucked under the wing of the Bone and next to the Aardvark. Last time I saw it was at Black Rock in 1997, they made some changes to it after Steve bought it.

[StraumliBlight]

Aviation Week: SpaceOps: Dream Chaser Reality Check [Oct 22]

In an interview with Aviation Week, Sierra Space says ending its commitment to fly NASA cargo was the fastest path to first flight. “We were mutually aligned to modify the contract,” said Dan Polis, vice president of Engineering Solutions and Propulsion Systems and Dream Chaser program manager. “We have been working closely with NASA on a path, and we felt that we were ready to fly ... This was favorable for us to get to first flight more quickly.

[...]

The free flight “gives us flexibility to use the vehicle … to support national security, as well as NASA and commercial partners,” Polis said. “We’ve already begun conversations with both civil and national security customers.

[...]

Sierra Space met one of those milestones last week when Dream Chaser completed electromagnetic interference and compatibility testing at NASA’s Kennedy Space Center (KSC). A captive tow test on the KSC runway is planned for the second week of November. That would be followed by acoustic testing in the KSC Space Station Processing Facility.

Other milestones ahead of flight are an integrated hot-fire test and an integrated hardware/software mission systems test, Polis said.

[...]

For Dream Chaser’s rescheduled Q4 2026 debut, Sierra Space still plans to fly on a United Launch (ULA) Alliance Vulcan rocket, but is considering alternatives. “ULA has been a great partner, but we are actively considering other possibilities, depending on customer need,” Polis said. “But it’s a tight partnership, and so very preliminary for us to consider anything else.”

[andrewi]

How much money NASA has spent on Dream Chaser is available at this link (you have to click on this IDV): https://usaspending.gov/award/CONT_IDV_NNJ16GX07B_8000

So NASA finally decided to cut its losses - basically very little money left in award - If I can add up right, that totals 1.485 Billion U$D (see above from 2016 to 2025) it paid for 6 ISS cargo deliveries (from the award of 1.6 Billion?) and got none and never will....  instead a free flyer demo... maybe.
Can also add the initial Commercial Crew develop program funding of 325 million between 2010 and 2012.
In comparison SpaceX delivered its 12 (Cargo Dragon) CRS-1 missions for 1.6 Billion and Northrop Grumman 8 (Cygnus) missions for 1.9 Billion.  They have both gone on with CRS-2 for a total of 32 successful Dragon Cargo missions to date and 22 for Cygnus.
I assume it only went on this long because the lifting body design (Dream Chaser) has been favourite of everyone but in the hands of Sierra Nevada the one commercial failure for NASA COTS program in general.  OK OK I was thinking Cargo not Crew - Starliner is heading for a similar judgement - but at least has been flying.

Compared to Artemis, SLS and Orion - small bickies....

I thought this better in the discussion thread as not an update but a comment on it.

[vt_hokie]

So is it your belief that even if Sierra Space pulls off a successful free flyer demo flight, it will not visit ISS on subsequent flights?

[andrewi]

So is it your belief that even if Sierra Space pulls off a successful free flyer demo flight, it will not visit ISS on subsequent flights?

Even with a successful demo flight - NASA is no longer funding DreamChaser.   So who will pay for future flights?   No ISS CRS contract anymore.

Any commercial venture would probably only go with a proven vehicle esp if asking for a NASA supplement.  The demo doesn't show refurbishment costs -  will remain unknown as no money to refurb DreamChaser. 

What commercial venture needs a LEO cargo delivery?   The commercial ISS replacements?   The current proposals that have Sierra Space as a partner may not procede with Sierra Space, as Sierra Space have shown themselves unable to develop DreamChaser on a reasonable budget even if you let timeliness slide.   

DreamChaser was potentially about return of cargo not just cargo delivery which isn't a commericial market currently and Dragon already provides capability at a known cost.   While DreamChaser may launch satellites on its Demo flight- it is an unnecessary expense to launch LEO satelites (at hundreds of millions) which a launch vehicle can provide without DreamChaser.

In General - US companies (Sierra Space in this case) need to change their mindset about Space vehicle development.  Esp costs.   I can only think of 3 companies that have shown they can get value from Government and private funding - RocketLab (Neutron development costs modest - ie sustainable), SpaceX and maybe York Space.   The legacy big companies (SpaceX is probably the biggest Space Company now but not legacy) only seem to be able to deliver to Defence at non market prices.   The Chinese are coming and like the EV market -  they are coming to own it.  Space is the same as all markets - if you can't compete on cost and reliability - you are not competing.  It has barriers to entry - technology, skills and money - these are not barriers to the Chinese.

So is DreamChaser dead?  Probably - I can't see anybody fronting more money.  Long term, I thought design flawed - the shooting star component - a disposed third stage after a disposed 2nd stage?.  A re-usable vehicle that has a non reusable major component - its engines.  It made for a great test platform (that is yet to fly - pls fly) for a favourite design path that has yet to find a market success  - the Shuttle was amazing in capability and use - but not cheap and unfortunately not reliable or even reusable (SRBs and big 1st stage tank disposed effectively) with out high cost refurbishment.  Possibly the most successful exponent of lifting body is the X-37 but again a disposable second stage.

I wish DreamChaser all the best in its demo flight.  But the capability already exists at a cheaper price and Sierra Space have shown (IMO) they are not the company to develop a similar cost capability let alone same or cheaper alternative.

[vt_hokie]

Perhaps this is the problem with the CCDev program from which DC emerged. Trying to spur innovation by contracting for a critical near-term mission for a risk-averse agency just combines two conflicting goals. The counterpoint I guess is the improbable success of SpaceX. But if we are going to pursue reusable lifting body shuttles or anything really that requires a bit more room for development issues in the name of advancement, it can't be just for a few missions to an aging space station. I'm speaking off the cuff, so maybe my stream of consciousness is on the wrong track, but are we maybe seeing the same thing now with Starship vs Artemis and the desire to land on the moon in the near term?

[DanClemmensen]

So is it your belief that even if Sierra Space pulls off a successful free flyer demo flight, it will not visit ISS on subsequent flights?

Even with a successful demo flight - NASA is no longer funding DreamChaser.   So who will pay for future flights?   No ISS CRS contract anymore.

I wish DreamChaser all the best in its demo flight.  But the capability already exists at a cheaper price and Sierra Space have shown (IMO) they are not the company to develop a similar cost capability let alone same or cheaper alternative.

NASA no longer has a contractual obligation to buy CRS missions from Sierra. However, If the demo flight shows that the thrusters work (and other stuff, of course) then NASA can presumably choose to buy a CRS mission, in order to provide redundancy for Cygnus. DreamChaser can be berthed instead of docked, and this provides more scheduling flexibility than using Cargo Dragon, especially when Cargo Dragon is being used for ISS reboost.

[thespacecow]

Aviation Week: SpaceOps: Dream Chaser Reality Check [Oct 22]

One notable news from this article is that DC200/300 is gone:

Sierra Space previously planned a crewed Dream Chaser variant, known as the DC-200 series, and a national security vehicle, the DC-300, but those designations are no longer active, the company said.

"We continue to evaluate Dream Chaser variants and assess future capabilities based on customer-driven mission needs, including defense, civil and commercial," Sierra Space said.

[Blackhorse]

Those two ? 
https://forum.nasaspaceflight.com/index.php?topic=46038.msg2679297#msg2679297

Seems pretty clear that SNC has its back against the wall. They are laser-focusing on first flight of the Dream Chaser cargo vehicle they have almost finished.

Can't help thinking about XCOR Lynx, in the sense that the first vehicle was almost finished when the company went under.

[JAFO]

I don't know if this is good or bad...

Tenacity looks like a rescue puppy forlornly looking out of her cage with her nose pressed against the bars, hoping someone will let her out to run.

https://twitter.com/theinformation/status/1986588173393141996

[vt_hokie]

Does this make it less likely that DC will fulfill its original purpose by visiting ISS on a subsequent flight if the free flight demo goes well?