Sierra Space Dream Chaser DISCUSSION Thread (was SNC)

[adrianwyard]

Interesting that this new animation depicts white thermal blankets on the leeward side rather than the tiles we see on the actual vehicle. I wonder if they considered blankets earlier then rejected them or if this was just artistic license.

[whitelancer64]

Interesting that this new animation depicts white thermal blankets on the leeward side rather than the tiles we see on the actual vehicle. I wonder if they considered blankets earlier then rejected them or if this was just artistic license.

*snip youtube video*

I don't think those are blankets, the tiles are put on in panels, as seen in the picture here: https://forum.nasaspaceflight.com/index.php?topic=29416.msg2520006#msg2520006

Each panel section does have a tiled texture, it's just not clearly seen until the close up on the "Tenacity" at about 2:00 minute mark.

[adrianwyard]

Yeah, too small to be blankets. I bet the animator just found a texture bitmap for shuttle blankets and used it for the white tiles. Actual tiles are pretty smooth:

[abaddon]

Sierra Space is dedicated to ushering in the next era of space exploration with its revolutionary fleet of Dream Chaser spaceplanes.

Under the #NASA CRS2 contract, the fleet (including Tenacity) will provide a minimum of seven uncrewed cargo service missions to and from the ISS.

I have a vague memory that Sierra Space committed to build one space plane for the CRS2 contract, but I can't find a reference now, so the "fleet" reference has me wondering if that was true and if anything has changed since then.  Anyone have any information on how many spaceplanes SS is required to build contractually, or information on any other spaceplanes they are actively building?  (Apologies in advance if I missed that information in the thread previously, I don't recall seeing anything about it and didn't find anything with a quick scan).

[JAFO]

Sierra Space is dedicated to ushering in the next era of space exploration with its revolutionary fleet of Dream Chaser spaceplanes.

Under the #NASA CRS2 contract, the fleet (including Tenacity) will provide a minimum of seven uncrewed cargo service missions to and from the ISS.

I have a vague memory that Sierra Space committed to build one space plane for the CRS2 contract, but I can't find a reference now, so the "fleet" reference has me wondering if that was true and if anything has changed since then.  Anyone have any information on how many spaceplanes SS is required to build contractually, or information on any other spaceplanes they are actively building?  (Apologies in advance if I missed that information in the thread previously, I don't recall seeing anything about it and didn't find anything with a quick scan).

And then there were two...[/font][/size]
Aug 30, 2022

https://twitter.com/SierraSpaceCo/status/1564649662958772229?ref_src=twsrc%5Etfw%7Ctwcamp%5Etweetembed%7Ctwterm%5E1564649662958772229%7Ctwgr%5Eff5c784f0cd993bb5f4f817b3ce85f6e8696d0b0%7Ctwcon%5Es1_&ref_url=https%3A%2F%2Fforum.nasaspaceflight.com%2Findex.php%3Faction%3Dprofileu%3D14344area%3Dshowpostsstart%3D80

[Kiwi53]

Each tile is unique in design, and differ in size, shape, thickness, and density. They plan to re-waterproof between missions similar to Shuttle.

Oh dear.
That doesn't seem at all like a formula for rapid reuse, but maybe that's not a Sierra Space design goal?

[Asteroza]

Each tile is unique in design, and differ in size, shape, thickness, and density. They plan to re-waterproof between missions similar to Shuttle.

Oh dear.
That doesn't seem at all like a formula for rapid reuse, but maybe that's not a Sierra Space design goal?

Rapid reuse is not likely a goal if they are exclusively riding on Vulcan. There will be plenty of time to do maintenance between launch opportunities for the foreseeable future.

Now, if they were riding on SpaceX, then yes, they would have to step up their game. But, the physical size of the vehicle make automating the rewaterproofing step much easier, compared to needing a gigantic OPF bay and workforce like the shuttle. Tile replacement depends on their inventory plan though. For example, having a full set of tile molds ready, but only baking tiles when needed, based on the speed of SpaceX's tile hatchery, suggests that might be a viable approach over having a full set of tiles in storage. If the molds themselves are rapidly 3D printable then that avoids mold storage as well at the cost of mold print time.

[Lee Jay]

Each tile is unique in design, and differ in size, shape, thickness, and density. They plan to re-waterproof between missions similar to Shuttle.

Oh dear.
That doesn't seem at all like a formula for rapid reuse, but maybe that's not a Sierra Space design goal?

You have to realize that DC is dramatically smaller than Shuttle and that it's not in a debris field on the side of a launcher.

[JAFO]

Each tile is unique in design, and differ in size, shape, thickness, and density. They plan to re-waterproof between missions similar to Shuttle.

Oh dear.
That doesn't seem at all like a formula for rapid reuse, but maybe that's not a Sierra Space design goal?

She's also not sitting out on the pad for weeks on end being rained on or beat up by woodpeckers (tic).

Since Dream Chaser will be enclosed in the shroud before rolling out to the pad, I wonder how much waterproofing of the tiles is necessary, or if the waterproofing also does some other function aside from just keeping rain out? Is the humidity at the Cape be that bad that a tile would absorb moisture even in dry weather?

They can't fly an approach in any kind of weather without risking eroding many, many of the tiles so it's not to protect them in an IMC approach. Also, IIRC shuttle desigineers were worried that the damage caused by flying through rain might be enough to seriously impact the L/D of the vehicle and it might not even make the runway.

[litton4]

Doesn't look like they have gap fillers between the tiles - no concerns about structure flexing causing tiles to chip or crack?

https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=29416.0;attach=2218910;image

[whitelancer64]

Doesn't look like they have gap fillers between the tiles - no concerns about structure flexing causing tiles to chip or crack?

https://forum.nasaspaceflight.com/index.php?action=dlattach;topic=29416.0;attach=2218910;image

There are gap fillers, you just can't see them in that photo.

Here's one where you can see some of them:

[FutureSpaceTourist]

https://twitter.com/sierraspaceco/status/1712503437617942696

To help understand the Dream Chaser® spaceplane’s hypersonic aerodynamics before our ETA test flight in 2017, this 6% stainless steel scale model was tested at speeds up to Mach 14. The test included the use of rudder and wing actuation.

[Starmang10]

i dont like how sierra space is taking complete credit for the design, when it was based off of hl-20.  sad that its happening ngl

[whitelancer64]

i dont like how sierra space is taking complete credit for the design, when it was based off of hl-20.  sad that its happening ngl

HL-20 never got much further than a mockup build and system studies.

[JEF_300]

i dont like how sierra space is taking complete credit for the design, when it was based off of hl-20.  sad that its happening ngl

They aren't. It's not like the HL-20 program is being kept secret or something.

[Jim]

First Look: Sierra Space (@SierraSpaceCo) has provided NSF with these unreleased photos of Dream Chaser Tenacity's Thermal Protection System (TPS) tiles, as she continues preparations for her maiden flight to the ISS on ULA's Vulcan rocket.

They plan to re-waterproof between missions similar to Shuttle.

Why is this needed if the vehicle is encapsulated and not exposed to the elements?

[Robert_the_Doll]

First Look: Sierra Space (@SierraSpaceCo) has provided NSF with these unreleased photos of Dream Chaser Tenacity's Thermal Protection System (TPS) tiles, as she continues preparations for her maiden flight to the ISS on ULA's Vulcan rocket.

They plan to re-waterproof between missions similar to Shuttle.

Why is this needed if the vehicle is encapsulated and not exposed to the elements?

Not when it lands at the Shuttle Landing Facility at end of mission, and then has to be towed off back the processing facility several miles away. And that will be even more true when or if it ever lands somewhere else.

[Jim]

Not when it lands at the Shuttle Landing Facility at end of mission, and then has to be towed off back the processing facility several miles away. And that will be even more true when or if it ever lands somewhere else.

Not going to land if rain is eminent.  The shuttle was out on the pad in the rain.

[Robert_the_Doll]

Not when it lands at the Shuttle Landing Facility at end of mission, and then has to be towed off back the processing facility several miles away. And that will be even more true when or if it ever lands somewhere else.

Not going to land if rain is eminent.  The shuttle was out on the pad in the rain.

Moisture in the air, and it can rain while Tenacity is being towed off the runway. It is Florida, after all.

[ELinder]

We have arrived at a profound milestone in both our company’s journey and our industry’s future,” said CEO Tom Vice.

Tenacity, the first vehicle in the Dream Chaser fleet is complete, and will ship to NASA’s Neil Armstrong Test Facility in coming weeks.

I'm glad they're getting closer to shipping, but judging by the photos their definition of complete must be pretty loose.