Author Topic: SNC Dream Chaser DISCUSSION Thread  (Read 532328 times)

Offline ChrisGebhardt

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Re: SNC Dream Chaser DISCUSSION Thread
« Reply #1840 on: 08/29/2017 04:37 PM »
As far as this Hubble Servicing Mission mentioned in the article, I presume it would be limited to prop delivery, with no swap out of large components?

Hubble doesn't use propellant, as it would contaminate the mirror. The mission might be just to boost the orbit and add a deorbit motor. I would think changing out parts and instruments would be difficult for an uncrewed mission.
Replace "difficult" with "impossible".

Not sure why "uncrewed" gets the discussion as the proposal from SN is for a crewed mission to Hubble.

From the article. : "...and the Trump Administration in the United States is understood to be studying a proposal set forth by Sierra Nevada to use of Dream Chaser for a crewed servicing mission to the Hubble Space Telescope in the 2020s."

Offline Star One

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Re: SNC Dream Chaser DISCUSSION Thread
« Reply #1841 on: 08/29/2017 07:55 PM »

Offline Zed_Noir

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Re: SNC Dream Chaser DISCUSSION Thread
« Reply #1842 on: 08/29/2017 09:57 PM »
Some questions:

....

After the chopper drops, is there any chance now of higher test drops from the STS Carrier aircraft, Stratolaunch, or White Knight 2 before launch to LEO? I know White Knight 2 drops were cancelled for the manned version, but years have now passed.

....

The Shuttle Carrier Aircraft have both been retired Tom. What Stratolaunch will be up to is anybody's guess.
....


In theory the Virgin Orbital Comic Girl 747 carrier aircraft could do high altitude and hi speed drop tests of the Dream Chaser.

Offline brickmack

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Re: SNC Dream Chaser DISCUSSION Thread
« Reply #1843 on: 08/30/2017 02:20 AM »
Not sure why "uncrewed" gets the discussion as the proposal from SN is for a crewed mission to Hubble.

From the article. : "...and the Trump Administration in the United States is understood to be studying a proposal set forth by Sierra Nevada to use of Dream Chaser for a crewed servicing mission to the Hubble Space Telescope in the 2020s."

Also, even if it was an uncrewed mission (though I can't imagine any benefit to using a spaceplane for that), NASA already studied this immediately prior to STS-125 while trying to decide how to do another servicing flight, and found an unmanned mission to be feasible (though not with as wide a scope)

Online mikes

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Re: SNC Dream Chaser DISCUSSION Thread
« Reply #1844 on: 08/30/2017 02:21 PM »

Offline Rocket Science

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Re: SNC Dream Chaser DISCUSSION Thread
« Reply #1845 on: 08/30/2017 03:42 PM »
Congrats to SNC and to the Chinook and her flight crew! :)
"The laws of physics are unforgiving"
~Rob, Physics instructor, aviator, vintage auto racer

Online Lars-J

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Re: SNC Dream Chaser DISCUSSION Thread
« Reply #1846 on: 08/30/2017 11:10 PM »
For all the hoopla about this carry test, you'd think it was an actual drop test. If this is how they cover a captive carry test, I expect some sort of Superbowl-esque production for the drop test.

Offline JAFO

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Re: SNC Dream Chaser DISCUSSION Thread
« Reply #1847 on: 08/31/2017 04:37 AM »
Airplane I currently fly has a nose wheel steering tiller that allows +-70 deg of movement. We use it for taxiing and to position on the runway, then use the rudder for steering (which interconnects with +-8deg of NWS movement) for takeoff and landing. That's typical for the commercial aircraft I've flown, +-a few degrees.


To add, some light aircraft don't even have nose wheel steering and it is free to caster...

IIRC even some Soviet jet fighters used castering nose wheels, presumably to cut down on weight and complexity.

I learned to fly in an airplane with a castering nose wheel. You get used to it, but it's still a pain vs. a steering nose wheel.

Everything from the Diamond Katana to the B-29 and the NASA lifting bodies have had free castering nosewheels. The Katana was fun to fly but took practice to be able to taxi and park without nosewheel steering. If you ever see the B-29 an an airshow it sounds like a steampunk airplane as it gets underway with a combination of differential power and squealing hydraulic brakes. I can't find it but I recall seeing a photo of a lifting body in the flare with the nose gear cocked off to one side, it landed fine, but Milt Thompson had a few things to say about it in his books.


On landing if a tire blows on one of the rear wheels does having a nose skid vs. A steerable nose wheel help or hinder controlling the rollout ??

Dual main tire system vehicles/aircraft (Shuttle, 737, etc), the good wheel is usually certified to carry a full gear truck load in an emergency. Land, roll out straight ahead or clear the runway on a high speed taxiway and, depending on the aircraft, get a careful tow back to the gate or change the tire right there.

Single tire (DC), you're going to drag the wheel at some point. If you know beforehand (as a previous poster mentioned) that you've got a bad tire, you're going to plan to land on the good leg, hold the bad one off as long as possible, and keep it going straight with a combination of aerodynamic control, nose wheel steering, and maybe gentle opposite braking until you can't keep it up any more, then it's up to how much friction/drag the bad leg causes if you're going to be a hero or if you're going to go off the runway.

From when I've read, DC did all of that on her first flight until the wing tip had to come down and she departed control and tumbled. JMPO, but I don't think a steerable nosewheel would have been able to keep DC on the runway and from flipping over with her gear up and locked, the landing speed was too high and the friction of the dragging wingtip would have been too much for any kind of steerable nose wheel to overcome. Whether or not she could have stayed on the runway with a steerable nosewheel and a bad tire is something I'll leave to the SNC engineers.



And Congrats to SNC today, I can imagine for the last few years she's been sleeping, remembering what da Vinci said:
"Once you have tasted flight, you will forever walk the earth with your eyes turned skyward, for there you have been, and there you will always long to return."

Go Dream Chaser!!!!
« Last Edit: 08/31/2017 08:00 AM by JAFO »
Anyone can do the job when things are going right. In this business we play for keeps.
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Offline Rocket Science

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Re: SNC Dream Chaser DISCUSSION Thread
« Reply #1848 on: 08/31/2017 12:59 PM »
For all the hoopla about this carry test, you'd think it was an actual drop test. If this is how they cover a captive carry test, I expect some sort of Superbowl-esque production for the drop test.
Yes and we are planning a "half-time wardrobe malfunction" as well...
"The laws of physics are unforgiving"
~Rob, Physics instructor, aviator, vintage auto racer

Offline vapour_nudge

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Re: SNC Dream Chaser DISCUSSION Thread
« Reply #1849 on: 08/31/2017 01:10 PM »
For all the hoopla about this carry test, you'd think it was an actual drop test. If this is how they cover a captive carry test, I expect some sort of Superbowl-esque production for the drop test.
Yes and we are planning a "half-time wardrobe malfunction" as well...
But nothing like the Six Million Dollar Man opening scene I hope  ;)

Offline Rocket Science

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Re: SNC Dream Chaser DISCUSSION Thread
« Reply #1850 on: 08/31/2017 01:23 PM »
For all the hoopla about this carry test, you'd think it was an actual drop test. If this is how they cover a captive carry test, I expect some sort of Superbowl-esque production for the drop test.
Yes and we are planning a "half-time wardrobe malfunction" as well...
But nothing like the Six Million Dollar Man opening scene I hope  ;)
Nah no need, she already passed her roll-over survive-ability test... ;)
"The laws of physics are unforgiving"
~Rob, Physics instructor, aviator, vintage auto racer

Offline yg1968

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Re: SNC Dream Chaser DISCUSSION Thread
« Reply #1851 on: 08/31/2017 01:29 PM »
For all the hoopla about this carry test, you'd think it was an actual drop test. If this is how they cover a captive carry test, I expect some sort of Superbowl-esque production for the drop test.

I loved their webcast. It was well done. I wished that it had continued until the end of the test.

These webcasts provide good publicity for a program that doesn't make the news as much as it should. I hope that SNC will have webcasts for their other tests as well.
« Last Edit: 08/31/2017 01:30 PM by yg1968 »

Offline yg1968

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Re: SNC Dream Chaser DISCUSSION Thread
« Reply #1852 on: 08/31/2017 01:34 PM »
I liked that they took questions during the webcast. One of the interesting things that Steve Lindsey said was that DC was a LEO spacecraft only. He admitted that wings aren't very useful for Mars or the Moon but said that DC's goal is to be a very good and reliable LEO spacecraft. This isn't surprising but I still appreciate their honesty on this point.
« Last Edit: 08/31/2017 01:37 PM by yg1968 »

Offline yg1968

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Re: SNC Dream Chaser DISCUSSION Thread
« Reply #1853 on: 08/31/2017 03:03 PM »
As far as this Hubble Servicing Mission mentioned in the article, I presume it would be limited to prop delivery, with no swap out of large components?

Hubble doesn't use propellant, as it would contaminate the mirror. The mission might be just to boost the orbit and add a deorbit motor. I would think changing out parts and instruments would be difficult for an uncrewed mission.
Replace "difficult" with "impossible".

Not sure why "uncrewed" gets the discussion as the proposal from SN is for a crewed mission to Hubble.

From the article. : "...and the Trump Administration in the United States is understood to be studying a proposal set forth by Sierra Nevada to use of Dream Chaser for a crewed servicing mission to the Hubble Space Telescope in the 2020s."

There were reports that this crewed DC mission had been proposed by SNC to Trump's NASA transition team at the beginning of 2017. But I haven't heard of it since then. Perhaps SNC will renew its "sales pitch" to the new NASA administrator.
« Last Edit: 08/31/2017 03:18 PM by yg1968 »

Offline yg1968

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Re: SNC Dream Chaser DISCUSSION Thread
« Reply #1854 on: 08/31/2017 03:14 PM »
Will Dream Chaser have to do a demonstration mission like SpaceX's COTS 2+ and Orbital ATK's Orb-D1 before operational missions?

No. Although, there wasn't much of a difference between a COTS demo flight and an operational CRS flight. So I don't think that it makes much of a difference. In other words, I am guessing that DC's first CRS2 flight will be treated like a demo flight by NASA and SNC. 
« Last Edit: 09/01/2017 12:48 AM by yg1968 »

Offline TomH

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Re: SNC Dream Chaser DISCUSSION Thread
« Reply #1855 on: 08/31/2017 06:35 PM »
Perhaps SNC will renew its "sales pitch" to the new NASA administrator.

Hubble may be dead before we have one. I still think ITSy would be better suited and flying sooner.

Online QuantumG

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Re: SNC Dream Chaser DISCUSSION Thread
« Reply #1856 on: 09/01/2017 12:41 AM »
Can everyone talking about SpaceX on this thread please delete their comments? FFS. Not every thread has to be about SpaceX.
Jeff Bezos has billions to spend on rockets and can go at whatever pace he likes! Wow! What pace is he going at? Well... have you heard of Zeno's paradox?

Offline deruch

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Re: SNC Dream Chaser DISCUSSION Thread
« Reply #1857 on: 09/02/2017 02:20 AM »
<moved from updates thread>
Quote
Who needs a moon to do an Eclipse... #DreamChaser #Eclipse2017 @SierraNevCorp @NASAArmstrong

https://twitter.com/dutchspace/status/903332819639967744

That's no moon.  It's a space..... ship.


Shouldn't reality posts be in "Advanced concepts"?  --Nomadd

Offline rockets4life97

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Re: SNC Dream Chaser DISCUSSION Thread
« Reply #1858 on: 11/08/2017 09:06 PM »
Michael Baylor: Would the chopper used in the test show up on the flight tracker you are watching?

I'm wondering what other signs we might expect to see that I a test might be coming/in-progress.

Edit: Sorry, I didn't see the discussion thread. A mod can move if they want.
« Last Edit: 11/08/2017 09:08 PM by rockets4life97 »

Offline Michael Baylor

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Re: SNC Dream Chaser DISCUSSION Thread
« Reply #1859 on: 11/08/2017 09:10 PM »
Michael Baylor: Would the chopper used in the test show up on the flight tracker you are watching?

I'm wondering what other signs we might expect to see that I a test might be coming/in-progress.

Edit: Sorry, I didn't see the discussion thread. A mod can move if they want.
No other traffic in the vicinity showing up. According to the flight tracker website most helicopters do not show up as they have different tracking equipment.

https://www.flightradar24.com/how-it-works

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