Author Topic: Dream Chaser making impressive progress ahead of CCDev-3  (Read 124051 times)

Offline dbhyslop

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Re: Dream Chaser making impressive progress ahead of CCDev-3
« Reply #40 on: 01/27/2012 06:57 PM »
Not necissarily.  Assuming an intact abort, the range and cross range that the DC offers actually allows one to know where it is coming down as opposed to just dropping somewhere in the water and waiting for someone to come and fish them out. 

Does anyone have a general guess of what altitude it would reach from a pad abort, given the approximate weight and thrust?  I'm assuming it would do some sort of roll/pitch maneuver to come over the top of the loop and transition into gliding flight while keeping any g's positive.

Offline Rocket Science

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Re: Dream Chaser making impressive progress ahead of CCDev-3
« Reply #41 on: 01/27/2012 07:10 PM »
I've done Pad Aborts with the HL-20 in Orbiter. It's a real "no-brainer" for any pilot. Should be the same for DC on the SLF and or what used to be the "skid strip"...
« Last Edit: 01/27/2012 07:12 PM by Rocket Science »
"The laws of physics are unforgiving"
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Offline Lee Jay

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Re: Dream Chaser making impressive progress ahead of CCDev-3
« Reply #42 on: 01/27/2012 07:25 PM »
I've done Pad Aborts with the HL-20 in Orbiter. It's a real "no-brainer" for any pilot. Should be the same for DC on the SLF and or what used to be the "skid strip"...

It sounds a little complex for the vehicle design to me.

On the one hand, you have a fully-loaded ~25,000 pounds vehicle that has to accelerate hard straight up against gravity to get away from an exploding launch vehicle, while on the other hand the same engines need to serve the same purpose as the OMS system on Shuttle - precisely and delicately altering orbital parameters.  So, you need engines that can apply anywhere between ~10g to a fully-loaded vehicle and 0.1g to a mostly-empty vehicle.  I don't understand how they're doing that with those hybrid motors.

Offline Rocket Science

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Re: Dream Chaser making impressive progress ahead of CCDev-3
« Reply #43 on: 01/27/2012 07:41 PM »
I've done Pad Aborts with the HL-20 in Orbiter. It's a real "no-brainer" for any pilot. Should be the same for DC on the SLF and or what used to be the "skid strip"...

It sounds a little complex for the vehicle design to me.

On the one hand, you have a fully-loaded ~25,000 pounds vehicle that has to accelerate hard straight up against gravity to get away from an exploding launch vehicle, while on the other hand the same engines need to serve the same purpose as the OMS system on Shuttle - precisely and delicately altering orbital parameters.  So, you need engines that can apply anywhere between ~10g to a fully-loaded vehicle and 0.1g to a mostly-empty vehicle.  I don't understand how they're doing that with those hybrid motors.
[/quote
I agree with you about the motors Lee Jay. We talked about it a while back on the main Dream Chaser thread. Seems like SNC has had some breakthgrough in that area that they are not telling us yet and I guess they don't have to reaveal it to anyone.




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Offline RocketmanUS

For ISS it is 2 to 7 crew-

So it needs 2 to fly it to ISS? If so why not just 1?

Then for a rescue mission that only leaves 5 seats and would need 6 seats to get all 6 ISS crew of station.
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Offline PahTo

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Re: Dream Chaser making impressive progress ahead of CCDev-3
« Reply #45 on: 01/27/2012 08:06 PM »
Nice article--thanks Chris.

Re: launch vehicle being the Atlas V and EDS.  Isn't the RD-180 a package deal, sealed up and simply bolted on to the bottom?  Seems human rating/EDS would require involvement with the rocket engine, so how will this be handled?

Has Delta IV been off the table from the start due to cost, USAF resistance to human rating the RS-68/RS-68A+vehicle, or both?

Would the Atlas V be in a 401 or 402 config?

Good conversation about LAS.

Naturally, I like the DC, though in an earlier poll, I went with Atlas V + CST-100 as the next US manned vehicle to ISS.


Offline Pheogh

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Re: Dream Chaser making impressive progress ahead of CCDev-3
« Reply #46 on: 01/27/2012 08:54 PM »
Do we have any experience with exposing a pilot to those kind of instant g-loads (pad abort) and then having them perform an un-powered landing? Again not trying to throw cold water on it just sounds quite a bit hairier than going along for the ride.

I think the thing that is really getting me here is that I seem to recall an interview with either John Young or Story where they were very forthcoming about abort scenarios with the orbiter that had them returning to the cape? I believe one of them even used the word "fantasy".

Offline Lee Jay

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Re: Dream Chaser making impressive progress ahead of CCDev-3
« Reply #47 on: 01/27/2012 08:55 PM »
Would the Atlas V be in a 401 or 402 config?

402, I think.

Offline Lee Jay

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Re: Dream Chaser making impressive progress ahead of CCDev-3
« Reply #48 on: 01/27/2012 08:57 PM »
Do we have any experience with exposing a pilot to those kind of instant g-loads (pad abort) and then having them perform an un-powered landing? Again not trying to throw cold water on it just sounds quite a bit hairier than going along for the ride.

What, you don't think you could accurately pilot a low-glide-ratio lifting body seconds after being rear-ended by a train to escape a massive explosion?

Since the pad abort test is going to be uncrewed to a horizontal landing, I wonder if it even matters.

Offline Pheogh

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Re: Dream Chaser making impressive progress ahead of CCDev-3
« Reply #49 on: 01/27/2012 09:06 PM »
Do we have any experience with exposing a pilot to those kind of instant g-loads (pad abort) and then having them perform an un-powered landing? Again not trying to throw cold water on it just sounds quite a bit hairier than going along for the ride.

What, you don't think you could accurately pilot a low-glide-ratio lifting body seconds after being rear-ended by a train to escape a massive explosion?

Since the pad abort test is going to be uncrewed to a horizontal landing, I wonder if it even matters.

Your second statement makes the most sense. If it was designed to be automated from the start then that would be really amazing IMHO.

Offline martin hegedus

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Re: Dream Chaser making impressive progress ahead of CCDev-3
« Reply #50 on: 01/27/2012 09:19 PM »
Sorry, I probably should have mentioned that in the article. Yes, no fairing needed.

Needed or used?  :)

I doubt WTs can model it because of Re issues.  And it is outside the reach of CFD.  To model it with CFD one would probably have to use LES and that requires a huge amount of resources at those Re numbers.

And the demon is flutter and unpredictable lift.  So we will see if the demon shows up or not.

And, at this point I'm just a happy arm chair rocket scientist that happens to be an aerodynamicist.  So these are just my opinions.  :)

Offline manboy

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Re: Dream Chaser making impressive progress ahead of CCDev-3
« Reply #51 on: 01/27/2012 09:32 PM »
Do we have any experience with exposing a pilot to those kind of instant g-loads (pad abort) and then having them perform an un-powered landing? Again not trying to throw cold water on it just sounds quite a bit hairier than going along for the ride.

What, you don't think you could accurately pilot a low-glide-ratio lifting body seconds after being rear-ended by a train to escape a massive explosion?

Since the pad abort test is going to be uncrewed to a horizontal landing, I wonder if it even matters.

Your second statement makes the most sense. If it was designed to be automated from the start then that would be really amazing IMHO.
Well Buran and the X-37 did it...
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Offline Rocket Science

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Re: Dream Chaser making impressive progress ahead of CCDev-3
« Reply #52 on: 01/27/2012 09:47 PM »
Do we have any experience with exposing a pilot to those kind of instant g-loads (pad abort) and then having them perform an un-powered landing? Again not trying to throw cold water on it just sounds quite a bit hairier than going along for the ride.

What, you don't think you could accurately pilot a low-glide-ratio lifting body seconds after being rear-ended by a train to escape a massive explosion?

Since the pad abort test is going to be uncrewed to a horizontal landing, I wonder if it even matters.
Good one Lee Jay! ;D
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Offline Pheogh

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Re: Dream Chaser making impressive progress ahead of CCDev-3
« Reply #53 on: 01/27/2012 09:59 PM »
Do we have any experience with exposing a pilot to those kind of instant g-loads (pad abort) and then having them perform an un-powered landing? Again not trying to throw cold water on it just sounds quite a bit hairier than going along for the ride.

What, you don't think you could accurately pilot a low-glide-ratio lifting body seconds after being rear-ended by a train to escape a massive explosion?

Since the pad abort test is going to be uncrewed to a horizontal landing, I wonder if it even matters.

Your second statement makes the most sense. If it was designed to be automated from the start then that would be really amazing IMHO.
Well Buran and the X-37 did it...

Huh? not in an abort scenario, certainly you aren't saying a nominal landing scenario is the same as and abort from the pad?

Offline Chandonn

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Re: Dream Chaser making impressive progress ahead of CCDev-3
« Reply #54 on: 01/27/2012 10:10 PM »
So it needs 2 to fly it to ISS? If so why not just 1?

It's always a good idea to have a backup system available... even a backup for the pilot...

Offline Patchouli

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Re: Dream Chaser making impressive progress ahead of CCDev-3
« Reply #55 on: 01/27/2012 10:33 PM »
Do we have any experience with exposing a pilot to those kind of instant g-loads (pad abort) and then having them perform an un-powered landing? Again not trying to throw cold water on it just sounds quite a bit hairier than going along for the ride.



It should not be too different from performing a 9+ g turn in a fighter.



Offline Pheogh

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Re: Dream Chaser making impressive progress ahead of CCDev-3
« Reply #56 on: 01/27/2012 10:45 PM »
Do we have any experience with exposing a pilot to those kind of instant g-loads (pad abort) and then having them perform an un-powered landing? Again not trying to throw cold water on it just sounds quite a bit hairier than going along for the ride.



It should not be too different from performing a 9+ g turn in a fighter.




Did we perform any tests with this during the Apollo era, rocket sleds etc? Also, wasn't there a Soyuz abort at one point and do we know how the cosmonauts felt during the experience other than being relieved to be alive?

I'm not intending to go OT with all this or be argumentative I am just trying to picture what a winged vehicle flying vertical off the pad at more than 9g's then righting itself horizontally to glide back to a landing strip just a few miles away.

Doesn't seem impossible, just tricky and the details would be very interesting to me especially considering what a GIGANTIC deal was made of crew safety and commercial launch vehicles.

Offline dbhyslop

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Re: Dream Chaser making impressive progress ahead of CCDev-3
« Reply #57 on: 01/27/2012 11:19 PM »
I'm not intending to go OT with all this or be argumentative I am just trying to picture what a winged vehicle flying vertical off the pad at more than 9g's then righting itself horizontally to glide back to a landing strip just a few miles away.

Frankly it doesn't sound all that different from a SpaceShipOne flight except that it starts on the ground and doesn't go nearly as high.  It might actually be simpler than an Apollo abort which plenty of moving parts like folding canards, pitch motors, jettison motors, several drogues and parachutes.

Offline Lee Jay

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Re: Dream Chaser making impressive progress ahead of CCDev-3
« Reply #58 on: 01/27/2012 11:22 PM »
Also, wasn't there a Soyuz abort at one point and do we know how the cosmonauts felt during the experience other than being relieved to be alive?

That was a lot more acceleration.

Offline TomH

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Re: Dream Chaser making impressive progress ahead of CCDev-3
« Reply #59 on: 01/27/2012 11:27 PM »
It is a step in the right direction, crew and cargo to LEO. Having a fly back runway landing shuttle and also capsules is a good mix to have ( flexible future option ).

Once the Dream Chaser and CST-100 are flying then it would be good to see a team make a launcher for them that is low cost and reusable.

Agreed on the dissimilar redundancy.  As for a low cost launcher, I could envision a Dream Chaser atop a Falcon 9.  The question is whether Musk could ever see it.

Going forward, I'm concerned as to whether Dream Chaser will get a 'fair hearing' for CCDEV-3.... I'm concerned that there might be 'pressure' - from within NASA, by the old guard, and also from without - to ensure that an 'experienced' company (code word for Boeing) is also selected, regardless of what is in the nation's' long-term interest.  If the above conjecture is true, it would leave possibly the most innovative proposal - and one that has been worked on much longer than Boeing's - ie SNC's, out. And that would be unfortunate.

And part of the old guard's problem is cost. Falcon/Dragon is shaping up to be economical in a variety of ways. Reusability and RTLS may increase that. DC looks to be inexpensive in the RTLS department and again, the dissimilar redundancy is a big plus. With CST-100, Boeing is offering the same old same old. It's almost Apollo+/Orion lite. With the fact that Orion could be pressed into LEO service if it had to, I see Dragon and DC edging out the conceptually older Boeing capsule.  In fact, I think the fact that Orion is in the wings as an emergency backup may give the necessary confidence to go with DC only; we had no kind of capsule backup during STS. If DC can prove itself in a test launch, I think it may take the win. In any case, I do not see Blue Origin making it into the next round.

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