Dream Chaser making impressive progress ahead of CCDev-3

[adrianwyard]

The Dream Chaser motors are apparently derived from those used on SpaceShipOne (~15Klb class) x2, rather than RocketMotorTwo for SpaceShipTwo (~60Klb class).

http://sncspace.com/hybrid_detail.php?id=9

[sanman]

Does SNC plan to do some LAS testing? If so, when? I'd imagine they'd have to, if CCDev specifies LAS as a requirement.

[Lurker Steve]

I was wondering how difficult the GNC software was for a craft like the Dreamchaser.

Obviously, each and every commerical airliner has the ability for an auto pilot to land the plane. I remember the pilot on a flight I took told us after we had already landed that it's an FAA requirement to land use the auto pilot every 20 flights or so.

So the difference with DC, is obviously the airspeed, performing an un-powered decent, and the shape of the vehicle. Other than some information from the other X-vehicles (X-24, X-37, etc), I assume this has been done with other un-powered gliders before. Are there some more or less "standard" flight control algorithims used that just need to be adapted to each vehicle, or do you need to "re-invent the wheel" each time ?

[Chris Bergin]

Just so you know, we'll have two articles on SNC next week, following Lee Jay's visit to see Dream Chaser on behalf of NSF. Lots of good stuff coming!

[FinalFrontier]

Nicely dealt with Tom!

Thanks, (feeling sheepish) my first reply was not as tactful. Sometimes, I read something over after I post and realize I could have done better.

I am damn glad you made that point. Too often those flaws in STS go by the way side.


We should never forget.

[Go4TLI]

Nicely dealt with Tom!

Thanks, (feeling sheepish) my first reply was not as tactful. Sometimes, I read something over after I post and realize I could have done better.

I am damn glad you made that point. Too often those flaws in STS go by the way side.


We should never forget.

On the flip side approximately 900 people did get up there and back just fine. 

What happens too often is people assume that if a vehicle sits on top of a rocket and has a LAS that there is no danger.  That's wrong. 

[adrianwyard]

+1.

Placing the craft on top does remove the TPS debris problem, but you get new ones to manage. For example, with the tall skinny configuration the spacecraft adapter needs to be strong enough to deal with all the wind/turbulence the stack will face with a 10 t aerodynamically complex load on the far tip.

The wind tunnel testing of the integrated stack that's going on now (or completed) should tell them what they need to know. But I wonder if the operational DC could have wind launch criteria limitations that will make it look less competitive than, say DragonRider. Remember, for an ISS crew launch you have to launch exactly on time; no waiting for favorable winds. It will probably have runway abort cross-wind launch criteria too, just like the Shuttle orbiter.

[FinalFrontier]

Nicely dealt with Tom!

Thanks, (feeling sheepish) my first reply was not as tactful. Sometimes, I read something over after I post and realize I could have done better.

I am damn glad you made that point. Too often those flaws in STS go by the way side.


We should never forget.

On the flip side approximately 900 people did get up there and back just fine. 

What happens too often is people assume that if a vehicle sits on top of a rocket and has a LAS that there is no danger.  That's wrong. 

Thats other side of the proverbial double edged sword. Spaceflight isn't safe, neither is getting on the road or flying in an airplane.

Nothing should be taken for granted with this stuff.


However,  having the vehicle on top with an LAS does give you more safety and abort options and it does mitigate the falling debris issue we had with the side mount design of STS. Should never be forgotten how hard that issue was to combat, and it was never completely solved by the program's end, just mitigated.

[TomH]

+1.

Placing the craft on top does remove the TPS debris problem, but you get new ones to manage. For example, with the tall skinny configuration the spacecraft adapter needs to be strong enough to deal with all wind/turbulence the stack will face with a 10 t aerodynamically complex load on the far tip.

The wind tunnel testing of the integrated stack that's going on now (or completed) should tell them what they need to know. But I wonder if the operational DC could have wind launch criteria limitations that will make it look less competitive than, say DragonRider. Remember, for an ISS crew launch you have to launch exactly on time; no waiting for favorable winds. It will probably have runway abort cross-wind launch criteria too, just like the Shuttle orbiter.

That "Main Propulsion System" can be used for abort and for cross range cruising. Will the craft normally glide to a landing unpowered? In a sudden and stiff crosswind, would it be possible to engage those engines and cross vector (crab) into the crosswind just like airplanes do all the time? To what degree could it crab unpowered?

[Go4TLI]

+1.

Placing the craft on top does remove the TPS debris problem, but you get new ones to manage. For example, with the tall skinny configuration the spacecraft adapter needs to be strong enough to deal with all wind/turbulence the stack will face with a 10 t aerodynamically complex load on the far tip.

The wind tunnel testing of the integrated stack that's going on now (or completed) should tell them what they need to know. But I wonder if the operational DC could have wind launch criteria limitations that will make it look less competitive than, say DragonRider. Remember, for an ISS crew launch you have to launch exactly on time; no waiting for favorable winds. It will probably have runway abort cross-wind launch criteria too, just like the Shuttle orbiter.

That "Main Propulsion System" can be used for abort and for cross range cruising. Will the craft normally glide to a landing unpowered? In a sudden and stiff crosswind, would it be possible to engage those engines and cross vector (crab) into the crosswind just like airplanes do all the time? To what degree could it crab unpowered?

Crosswinds will be landing criteria defined within the known control authority of the vehicle.  For launch, crosswinds will be a launch criteria in the event of an abort. 

The engines will not be fired near the ground as nozzles dictate the performance of said engines.  At lower altitudes that can lead to flow sep in the nozzle and cause more problems than it solves. 

[Chris Bergin]

Found a cut off point for a 40 post back and forth splinter topic/willy measuring competition and coverted it into a Q&A thread here:
http://forum.nasaspaceflight.com/index.php?topic=29059.0

[Rocket Science]

+1.

Placing the craft on top does remove the TPS debris problem, but you get new ones to manage. For example, with the tall skinny configuration the spacecraft adapter needs to be strong enough to deal with all wind/turbulence the stack will face with a 10 t aerodynamically complex load on the far tip.

The wind tunnel testing of the integrated stack that's going on now (or completed) should tell them what they need to know. But I wonder if the operational DC could have wind launch criteria limitations that will make it look less competitive than, say DragonRider. Remember, for an ISS crew launch you have to launch exactly on time; no waiting for favorable winds. It will probably have runway abort cross-wind launch criteria too, just like the Shuttle orbiter.

That "Main Propulsion System" can be used for abort and for cross range cruising. Will the craft normally glide to a landing unpowered? In a sudden and stiff crosswind, would it be possible to engage those engines and cross vector (crab) into the crosswind just like airplanes do all the time? To what degree could it crab unpowered?

Tom,
 
With such a low L/D for this spacecraft we should remove from our heads typical a/c like operations. You are not going to shoot a missed approach and execute a go-round. If the conditions are not right, it (she “baby-orbiter” shouldn’t be landing there during normal ops. With its short runway requirements it would be best to use an alternate…

~Robert

[yg1968]

A couple of press releases by SNC on their recent CCDev-2 progress:
http://www.sncorp.com/press_more_info.php?id=493
http://www.sncorp.com/press_more_info.php?id=492

[yg1968]

The video says "No solid strapons" and "no abort blackzones." They are responding to ATK on the black zones and taking shots at Boeing for the solid strapon (the CST-100 uses the Atlas V 412; DC uses the Atlas V 402).

[TomH]

In thinking about CCDev downselect criteria, a few thoughts come to mind. IMHO, SpaceX made some good progress this past week. The rocket has flown; what will become the capsule has already been to ISS. I think this improves SpaceX's outlook immensely. In looking at a backup system that can provide dissimilar redundancy, I am pondering SNC vs. CST-100. Both give an alternate LV than F9, the same alternate LV being Atlas V. And yet CST is a capsule. SNC's DC provides a spacecraft that is much more dissimilar to Dragon than is CST-100. Further, it is most unlikely that we would ever see Dragon atop AV or CST-100 atop F9.

If, however, DC were chosen as the backup, is there not more likelihood that it is a vehicle which could be launched from either LV?

Let's just hypothetically assume a downselect to Dragon on F9 as primary and CST-100 on AV as the backup. Should a problem later develop with Dragon, not only would it stop being used, but F9 as well; both AV and CST-100 would need to be pressed into service. If a problem developed with F9 but not Dragon, we would likely not see Dragon moved to AV; again, both AV and CST would be pressed into service.

With DC, however, it seems there is a greater possibility of the spacecraft being able to launch on either of these LVs. Let's now assume a downselect to Dragon/F9 as primary and DC as backup. But this scenario might be different in that perhaps SNC might actually be willing to qualify DC on both AV and F9. If a problem developed with F9, SpaceX is unlikely to put Dragon on an AV. If however, a problem developed with Dragon and DC had to be pressed into service, securing an F9 might be done in a much more timely manner than reserving an AV. Having DC as backup and qualified on both AV and F9 seems far more of a possibility than ever seeing Dragon on AV or CST-100 on F9.

So, some questions come to mind:

How much extra would it cost to certify DC on both LVs?

Who would pay for it?

What is the likelihood SNC would consider it?

What is the likelihood that NASA would approve it?

Would it give DC an edge in the competition?

What are the technical issues of putting DC on F9? I know there's aerodynamics, mating, guidance interface. What about mass capability? Others?

Would this extra dissimilar redundancy be worth it?

Could such a scenario even give DC a boost in its chances as being chosen as the primary?

[Jim]

If, however, DC were chosen as the backup, is there not more likelihood that it is a vehicle which could be launched from either LV?

No, not any more than CST-100. 

Also, there won't be a backup chosen, both providers would fly missions, much like CRS.

[Jim]

1.  Who would pay for it?

2.  What is the likelihood that NASA would approve it?

3.  Would it give DC an edge in the competition?

4.  What are the technical issues of putting DC on F9? I know there's aerodynamics, mating, guidance interface. What about mass capability? Others?

5.  Could such a scenario even give DC a boost in its chances as being chosen as the primary?

1.  SNC
2.  NASA has no say
3.  No, because CST-100 is to be compatable with all launch vehicles (Atlas, Delta, Falcon, Liberty)
4.  No different than integrating on to Atlas
5.  no

[mmeijeri]

SNC's DC provides a spacecraft that is much more dissimilar to Dragon than is CST-100.

Not really important, since capsules are known to work. They are the safe and conservative solution. They are also more applicable to beyond LEO, as Lindenmoyer hinted at, though that will likely not be a criterion for the next round.

[Jim]

SNC's DC provides a spacecraft that is much more dissimilar to Dragon than is CST-100.

That is not a consideration.

[baldusi]

The video says "No solid strapons" and "no abort blackzones." They are responding to ATK on the black zones and taking shots at Boeing for the solid strapon (the CST-100 uses the Atlas V 412; DC uses the Atlas V 402).

It also said, that their LAS didn't need that much thrust, because Atlas 402 has thrust termination. I wonder if this means that their LAS won't support an Atlas 412. That would be a huge risk on the mass margins. Meanwhile, CST-100 could simply do a 422. I.e., CST has the risk of being more expensive, while DC would be sort of incompatible. Am I reading this right?