Author Topic: Grasshopper Discussion (including Grasshopper 2, aka F9R-Dev1) Thread 1  (Read 315517 times)

Offline 411rocket

  • Full Member
  • **
  • Posts: 261
  • Retired RCEME w/ tours in Cyprus, Croatia, Bosnia
  • Vancouver Island
  • Liked: 79
  • Likes Given: 114
Re: Grasshopper Discussion (including Grasshopper 2, aka F9R-1)
« Reply #40 on: 01/26/2014 07:12 AM »
GH2 may have flown but if is only 2m hop they may decide it is not worth releasing to public.

From the fairly recent overflight photo, it kind of looked like, the legs were in the process of being fitted.
Photo quality was poor, it is possible something elese was in progress. We also do not know for sure, when the photo was taken. But it was after, GH1 was moved off of the test pad, by the crane.

Offline MTom

  • Full Member
  • ***
  • Posts: 378
  • EU / Hungary
  • Liked: 107
  • Likes Given: 434
Re: Grasshopper Discussion (including Grasshopper 2, aka F9R-1)
« Reply #41 on: 01/26/2014 08:15 AM »
That seems like a silly way to test fatigue limits. Why wouldn't they just qualify the stage on a stand and then do metal sample tests?

You can do thousands of fatigue cycles in the time to prep the GH for one flight. Flights are more useful for operational issues like how the stage performs under various flight conditions, and identifying failure-prone parts or subsystems.

Agreed, once you know the loading the subsystem will need to endure, the testing must be done in a lab, if needed. In most cases the MTBF can be calculated, knowing the material properties and expected loading. However, there is nothing that beats real world tests.
Putting the first returned stage back on the test stand will be the real test of core structural integrity.  I believe that GH2/F9R-1 will again be a software development test bed.

I agree: with 3 engines this should be about devloping the capabilities of it, not about testing stuctural integrity.

The question is: what can be tested with 3 engines? What are the limits (altitude, velocity, downrange - inclusive return to launch site) for this test vehicle?

A think, they wanted step-by-step arrive theese limits. After that they will run tests to get the best return profile.
« Last Edit: 01/26/2014 08:45 AM by MTom »

Offline smoliarm

  • Full Member
  • ****
  • Posts: 479
  • Moscow, Russia
  • Liked: 164
  • Likes Given: 55
Re: Grasshopper Discussion (including Grasshopper 2, aka F9R-1)
« Reply #42 on: 01/26/2014 09:07 AM »
...

It generally took them a few weeks to release information, no matter the height of the hop.

The attached table shows that the typical delay on the video release is shorter, 3-4 days with one exception (obviously, SpaceX believes that GH program is an important part of their public image).
However, your implication is quite correct, the delay can be much longer than few days.
What happened once, can happen twice :)

Offline Ric Capucho

  • Member
  • Posts: 58
  • Liked: 20
  • Likes Given: 17
Grasshopper Discussion (including Grasshopper 2, aka F9R-1)
« Reply #43 on: 01/26/2014 12:51 PM »
GH2 may have flown but if is only 2m hop they may decide it is not worth releasing to public.

If there was even a quarter inch hop at McGregor, then SpaceX would have had to have an FAA permission and that would be viewable as a permit on the FAA website. No such permit, ergo no hop at McGregor.

TW
« Last Edit: 01/26/2014 02:58 PM by Tricky Woo »

Offline Avron

  • Canadian Member
  • Senior Member
  • *****
  • Posts: 4914
  • Liked: 146
  • Likes Given: 150
Re: Grasshopper Discussion (including Grasshopper 2, aka F9R-1)
« Reply #44 on: 01/26/2014 02:40 PM »

GH2 may have flown but if is only 2m hop they may decide it is not worth releasing to public.

If there was even a quarter inch hop at McGregor, then SpaceX would have had to have an FAA permissio  and that would be viewable as a permit on the FAA website. No such permit, ergo no hop at McGregor.

TW

Right now they cannot even fly GH1 if they want to do so.. There is no active licence for GH.

Offline cambrianera

  • Full Member
  • ****
  • Posts: 1396
  • Liked: 274
  • Likes Given: 229
Re: Grasshopper Discussion (including Grasshopper 2, aka F9R-1)
« Reply #45 on: 01/26/2014 03:03 PM »

GH2 may have flown but if is only 2m hop they may decide it is not worth releasing to public.

If there was even a quarter inch hop at McGregor, then SpaceX would have had to have an FAA permissio  and that would be viewable as a permit on the FAA website. No such permit, ergo no hop at McGregor.

TW

Right now they cannot even fly GH1 if they want to do so.. There is no active licence for GH.

There is the extension of the original permit:
https://www.faa.gov/data_research/commercial_space_data/permits/
Oh to be young again. . .

Offline Avron

  • Canadian Member
  • Senior Member
  • *****
  • Posts: 4914
  • Liked: 146
  • Likes Given: 150
Re: Grasshopper Discussion (including Grasshopper 2, aka F9R-1)
« Reply #46 on: 01/26/2014 03:10 PM »

There is the extension of the original permit:
https://www.faa.gov/data_research/commercial_space_data/permits/

My bad, its not on the other list for launches..

Offline Ric Capucho

  • Member
  • Posts: 58
  • Liked: 20
  • Likes Given: 17
Re: Grasshopper Discussion (including Grasshopper 2, aka F9R-1)
« Reply #47 on: 01/26/2014 03:13 PM »


There is the extension of the original permit:
https://www.faa.gov/data_research/commercial_space_data/permits/

My bad, its not on the other list for launches..

Oops, EP 12-008 is still in force for Texas. My bad too.

TW

Offline Robotbeat

  • Senior Member
  • *****
  • Posts: 26452
  • Minnesota
  • Liked: 6377
  • Likes Given: 4639
Re: Grasshopper Discussion (including Grasshopper 2, aka F9R-1)
« Reply #48 on: 01/26/2014 04:42 PM »
"GH2" should fly (& land) several times before a land landing of F9R is attempted. They will want to prove that the legs work as advertised, it makes all the sense in the world to do this before RTLS is attempted.
Why throw away a perfectly good first stage if there's a chance try won't have to?

Provided they can prove no appreciable risk to the public (and thus get FAA approval), I'm sure they'll give it a shot. The legs can't be that expensive. And if they can't get permission for a land landing in time, they will try a water landing (with legs extended).
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0

Online meekGee

  • Senior Member
  • *****
  • Posts: 7446
  • N. California
  • Liked: 3766
  • Likes Given: 796
Re: Grasshopper Discussion (including Grasshopper 2, aka F9R-1)
« Reply #49 on: 01/26/2014 08:38 PM »
GH2 may have flown but if is only 2m hop they may decide it is not worth releasing to public.

If there was even a quarter inch hop at McGregor, then SpaceX would have had to have an FAA permission and that would be viewable as a permit on the FAA website. No such permit, ergo no hop at McGregor.

TW

IMO the first "hop" will be zero-inch.  Legs don't have to leave the ground - just an integration test, thrust build-up till T/W=1, then cut then engine.  You can confirm the propulsion system works ok, and also measure the reaction of the legs to the change in load from 100 to 0%, and then to the sudden return from 0 to 100%.

ABCD - Always Be Counting Down

Online ChefPat

  • Full Member
  • ****
  • Posts: 1050
  • Earth, for now
  • Liked: 121
  • Likes Given: 1009
Re: Grasshopper Discussion (including Grasshopper 2, aka F9R-1)
« Reply #50 on: 01/26/2014 09:19 PM »
"GH2" should fly (& land) several times before a land landing of F9R is attempted. They will want to prove that the legs work as advertised, it makes all the sense in the world to do this before RTLS is attempted.
They can test the legs with the crane. It's supposed to be a soft landing anyway. If they want to test a harder landing, drop it from a little bit higher with the crane.
Playing Politics with Commercial Crew is Un-American!!!

Offline Lars_J

  • Senior Member
  • *****
  • Posts: 6161
  • California
  • Liked: 664
  • Likes Given: 195
Re: Grasshopper Discussion (including Grasshopper 2, aka F9R-1)
« Reply #51 on: 01/26/2014 09:22 PM »

"GH2" should fly (& land) several times before a land landing of F9R is attempted. They will want to prove that the legs work as advertised, it makes all the sense in the world to do this before RTLS is attempted.
Why throw away a perfectly good first stage if there's a chance try won't have to?

Provided they can prove no appreciable risk to the public (and thus get FAA approval), I'm sure they'll give it a shot. The legs can't be that expensive. And if they can't get permission for a land landing in time, they will try a water landing (with legs extended).

What exactly are you arguing against being thrown away? GH2 or the CRS-3  first stage? I'm not understanding what you mean.

I think there is 0% chance that they will try to land CRS-3 1st stage on land. The question my mind is whether or not they will:
A) fly without legs
B) fly with legs bolted on (non-deployable)
C) fly with legs that will be deployed before a water "landing"

Also - The launch is now just over a month away. We should have heard by now if a spot was being prepared as a landing area. I don't expect a land landing attempt until mid-2014 at the earliest.

Online Elmar Moelzer

  • Senior Member
  • *****
  • Posts: 2879
  • Liked: 475
  • Likes Given: 715
Re: Grasshopper Discussion (including Grasshopper 2, aka F9R-1)
« Reply #52 on: 01/26/2014 09:24 PM »
I think there is 0% chance that they will try to land CRS-3 1st stage on land.
Based on what evidence?

Offline Lars_J

  • Senior Member
  • *****
  • Posts: 6161
  • California
  • Liked: 664
  • Likes Given: 195
Grasshopper Discussion (including Grasshopper 2, aka F9R-1)
« Reply #53 on: 01/26/2014 09:27 PM »
I think there is 0% chance that they will try to land CRS-3 1st stage on land.
Based on what evidence?

Did you miss the "think"? :) or did you not read the rest of my post where I lay it out?

But I'm tired of arguing this with blue sky optimists. Why don't we just wait 5 weeks and find out who is right?
« Last Edit: 01/26/2014 09:29 PM by Lars_J »

Offline AJW

  • Full Member
  • ****
  • Posts: 587
  • Liked: 487
  • Likes Given: 62
Re: Grasshopper Discussion (including Grasshopper 2, aka F9R-1)
« Reply #54 on: 01/26/2014 09:31 PM »
I had wondered if before starting GH2 test hops they might first test the legs for susceptibility to heat damage by placing prototypes in proximity to an M1D during test fires at McGregor.  We saw plenty of smoke coming off the metal GH1 legs during hops, and I would expect composite legs to fair even worse.  There was a posting of a reflective coating added to the tail surfaces of SpaceShip Two near the rocket bell, and that would seem a logical step.  Depending on when the F9 V1.1 legs are extended during descent, if GH2 takes off with the legs extended, they may be exposed to more heat than an actual landing.
« Last Edit: 01/26/2014 09:58 PM by AJW »

Offline 411rocket

  • Full Member
  • **
  • Posts: 261
  • Retired RCEME w/ tours in Cyprus, Croatia, Bosnia
  • Vancouver Island
  • Liked: 79
  • Likes Given: 114
Re: Grasshopper Discussion (including Grasshopper 2, aka F9R-1)
« Reply #55 on: 01/26/2014 09:48 PM »
I had wondered if before starting GH2 test hops they might first test the legs for susceptibility to heat damage by placing prototypes in proximity to an M1D during test fires at McGregor.  We saw plenty of smoke coming off the metal GH1 legs during hops, and I would expect composite legs to fair even worse.  There was a posting of a reflective coating added to the tail surfaces of SpaceShip One near the rocket bell, and that would seem a logical step.  Depending on when the F9 V1.1 legs are extended during descent, if GH2 takes off with the legs extended, they may be exposed to more heat than an actual landing.

For all we know, that could have been the same material as the legs, attached to the test stand, when they tested that 3D printed part. Remember that plate, attached to the wall of the test stand.

GH2 taking off with the legs extended, would also make a good heat test as well.

Online meekGee

  • Senior Member
  • *****
  • Posts: 7446
  • N. California
  • Liked: 3766
  • Likes Given: 796
Re: Grasshopper Discussion (including Grasshopper 2, aka F9R-1)
« Reply #56 on: 01/26/2014 09:49 PM »
I think there is 0% chance that they will try to land CRS-3 1st stage on land.
Based on what evidence?

Did you miss the "think"? :) or did you not read the rest of my post where I lay it out?

But I'm tired of arguing this with blue sky optimists. Why don't we just wait 5 weeks and find out who is right?

I think it's because of the phrasing ...

"I think they won't fly with legs" (Even though Elon thinks they might) is a fair statement. It acknowledges that you don't know for sure.

"There's zero chance they'll fly with legs" is a much stronger statement.  It needs corroborating evidence, as in "I have inside information that the legs won't be ready in time".  Especially in the wider context of your post.

But the combination of both statements leaves us all wondering, at the edge of our seats....  :) 

Is there any bit of information that negates Elon's statement that they'll try it, to the point where it's a certainty that they won't?

I'm a bit skeptical myself that they'll get everything ready in time, mind you, but I don't see the certainty, one way or the other. 
ABCD - Always Be Counting Down

Offline Lars_J

  • Senior Member
  • *****
  • Posts: 6161
  • California
  • Liked: 664
  • Likes Given: 195
Re: Grasshopper Discussion (including Grasshopper 2, aka F9R-1)
« Reply #57 on: 01/26/2014 09:56 PM »
Any direct evidence? No - other than the (IMO) common sense arguments I have laid out that leads me to think so. And my gut feeling. But let's just wait and see.

Online Elmar Moelzer

  • Senior Member
  • *****
  • Posts: 2879
  • Liked: 475
  • Likes Given: 715
Re: Grasshopper Discussion (including Grasshopper 2, aka F9R-1)
« Reply #58 on: 01/26/2014 10:15 PM »
Any direct evidence? No - other than the (IMO) common sense arguments I have laid out that leads me to think so. And my gut feeling. But let's just wait and see.
Lars, I am OK with giving it a low chance of happening (I myself think it is a < 40% chance), but I would not use a strong word such as "0 chance". SpaceX has surprised us in the past. So I would be careful to use absolutes wherever they are involved (in positive and negative).

Offline TrevorMonty

CRS3 may still be able to demo a controlled water landing without legs. If they have found away to stop the spin without legs. Even with legs I'd be surprised if Spacex attempted land landing.

Tags: