Author Topic: Grasshopper Discussion (including Grasshopper 2, aka F9R-Dev1) Thread 1  (Read 465372 times)

Offline mvpel

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Though the legs seem lighter than expected at 2000kg. Those things are huge! How did you end up with that value?

The fairings have been described as "carbon fiber and aluminum honeycomb" in various sources. I presume that this means they have an aluminum honeycomb core with carbon-fiber facing.

Core Composites, Inc.
Quote
Aluminum honeycomb offers maximum stiffness and one of the highest strength to weight ratios of any structural core material available.

And if you take a close look at the attached image from the SpaceX factory floor, you can deduce that not only is the skin of the fairing mostly empty space thanks to the honeycomb, but so is the fairing itself.
"Ugly programs are like ugly suspension bridges: they're much more liable to collapse than pretty ones, because the way humans (especially engineer-humans) perceive beauty is intimately related to our ability to process and understand complexity. A language that makes it hard to write elegant code makes it hard to write good code." - Eric S. Raymond

Offline Owlon

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True, if used, the fins barely weigh much compared to a fully loaded first stage of F9R v1.1. Was just checking if anyone has managed to make an estimate  ;)

My current estimate of the f9v1.1 stage 1 structural mass is indeed in the range of 20000 kg(+/- 5% due to data inaccuracies).

Though the legs seem lighter than expected at 2000kg. Those things are huge! How did you end up with that value?

Here's the exact quote from twitter:

Quote from: Elon Musk
"...Needs to be ultra light. All 4 legs together (~60 ft span) weigh less than Model S."

https://twitter.com/elonmusk/status/330054002148515841

Offline GregA

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My 4yo daughter saw me reading here this morning, and saw a picture of a rocket on the right. She asked if she could watch a video of a rocket taking off, so I grabbed a random youtube video of a Delta launch.

After about a minute she said "Why isn't it going back down to land?".
Sorry, had to share :)

Offline mvpel

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My 4yo daughter saw me reading here this morning, and saw a picture of a rocket on the right. She asked if she could watch a video of a rocket taking off, so I grabbed a random youtube video of a Delta launch.

After about a minute she said "Why isn't it going back down to land?".
Sorry, had to share :)

I had the good fortune to attend a speech by futurist Mike Walsh earlier this year at a company IT retreat. He said, at one point, that the frontier of technological progress is defined by what young people take for granted.  :D
"Ugly programs are like ugly suspension bridges: they're much more liable to collapse than pretty ones, because the way humans (especially engineer-humans) perceive beauty is intimately related to our ability to process and understand complexity. A language that makes it hard to write elegant code makes it hard to write good code." - Eric S. Raymond

Offline mr. mark

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Wondering to myself if a F9R-1 demonstration could be presented at an airshow such as the Paris show.

Offline Lar

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My 4yo daughter saw me reading here this morning, and saw a picture of a rocket on the right. She asked if she could watch a video of a rocket taking off, so I grabbed a random youtube video of a Delta launch.

After about a minute she said "Why isn't it going back down to land?".
Sorry, had to share :)

Ask ULA, it's their rocket operation. Grin.

Out of the mouths of babes...

Wondering to myself if a F9R-1 demonstration could be presented at an airshow such as the Paris show.

Could? Yes, just takes logistics.
Should? Seems like a lot of risk to spectators that aren't going to be far enough away. So no.
Would? Seems like a lot of cost for minimal oomph. The people that matter already know, and the people who don't know may not matter.

I'd take the no side of the bet for pretty long odds.
« Last Edit: 07/25/2014 11:30 pm by Lar »
"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

Offline cscott

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Wondering to myself if a F9R-1 demonstration could be presented at an airshow such as the Paris show.

Could? Yes, just takes logistics.
Should? Seems like a lot of risk to spectators that aren't going to be far enough away. So no.
Would? Seems like a lot of cost for minimal oomph. The people that matter already know, and the people who don't know may not matter.

I'd take the no side of the bet for pretty long odds.

If I had to make the bet, I'd bet on a US event (ITAR, logistics of shipping the core, etc).  Oshkosh might work -- but probably not in the near future.  Only after launch&land becomes boring and routine would we see it evangelized to the general public.  It would be a heck of a promo for tickets to Mars.  But I wouldn't expect to see it until tickets to Mars were a thing the general public could buy.

Offline OSE

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Does anyone know when the F9R-Dev2 flights in New Mexico are planned to start? Or even if it has been built yet?

Offline Zond

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According to the FAA the F9R-Dev1 made a flight on the first of August.

Offline Tovmasyanara

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Very well. We must wait video a few days.

Offline sojourner

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Does anyone know when the F9R-Dev2 flights in New Mexico are planned to start? Or even if it has been built yet?
From the floating launchpad thread:
Quote from: Rand Simberg
Talked to Gwynne yesterday and she confirmed that they're working permission on flyback, but next landing will be on a barge. via Twitter

So there ya go.

Plus this:
Quote from: Rand Simberg
No more water landings. And Spaceport America has cost more and taken longer than expected.

I take that to mean they will try a landing at CCAFS before we see any F9R testing from New Mexico, if at all...

Offline OSE

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According to the FAA the F9R-Dev1 made a flight on the first of August.

I drive through Waco about once a month and have been meaning to go by McGregor for awhile now. I was there yesterday (Aug. 3rd) around 6 pm and got a few pictures of F9R-Dev1, Grasshopper, and the F9 tripod test stand with a 1st stage on it (not sure which one, I saw another post saying AsiaSat 6's core was on the stand about a week ago so this may be it).

The grid fins on F9R-Dev1 looked like they were not completely parallel with the tank body.

Unfortunately I did not bring my DSLR and had to take the pictures using my phone so they are a little blurry.

Offline cscott

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According to the FAA the F9R-Dev1 made a flight on the first of August.

I drive through Waco about once a month and have been meaning to go by McGregor for awhile now. I was there yesterday (Aug. 3rd) around 6 pm and got a few pictures of F9R-Dev1, Grasshopper, and the F9 tripod test stand with a 1st stage on it (not sure which one, I saw another post saying AsiaSat 6's core was on the stand about a week ago so this may be it).

Well, that brackets their setup/break down times somewhat.  Less than two days to disassemble the caterpillar crane, clean up the pad, and fly the stage, then less than two days to put the crane back together and get the stage back on the crane.  The bounds are probably considerably tighter than that, but this is what a "fair witness" can state.

Offline meekGee

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The crane merely backs away - you can actually see it in the downward looking videos.

But otherwise, yes.
ABCD - Always Be Counting Down

Offline executor314

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1000m F9R flight, new actuators, new software according to Reisman.  ~25:40 in the video.

http://new.livestream.com/AIAAvideo/space2014/videos/58462185

Offline Norm38

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^^^
Reisman said they'd launched Asiasat 8 early that morning, meaning that was filmed 8/5.  And the F9R flight last Friday would be 8/2.  He also said video would be on YouTube very soon.  Just checked, don't see anything yet.

Offline SVBarnard

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1000m F9R flight, new actuators, new software according to Reisman.  ~25:40 in the video.

http://new.livestream.com/AIAAvideo/space2014/videos/58462185

What are actuators? I know it has something to do with stability.

Online Zardar

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1000m F9R flight, new actuators, new software according to Reisman.  ~25:40 in the video.

http://new.livestream.com/AIAAvideo/space2014/videos/58462185

What are actuators? I know it has something to do with stability.

Probably the "grid fins", (or the gizmos driving them.) - the new vanes that they have near the top of the F9R-Dev for aerodynamic stability/steering during re-entry through the atmosphere.

Might also refer to the TVC (thrust vector control) actuators - basically the hydraulic rams that wiggle the main engines.
« Last Edit: 08/09/2014 03:01 pm by meekGee »

Offline alang

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I've tried to find a discussion of this using the search utility but haven't found it.
Has anyone tried to estimate the effectiveness of the grid fins at various speeds? I'm curious to what extent they could change the angle of attack of a re-entering stage and therefore cause lift and possibly significantly reduce the need for such a fuel intensive boost back.
Presumably this is dependent on whether they can be deployed whilst the stage is hypersonic?

Offline deruch

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I've tried to find a discussion of this using the search utility but haven't found it.
Has anyone tried to estimate the effectiveness of the grid fins at various speeds? I'm curious to what extent they could change the angle of attack of a re-entering stage and therefore cause lift and possibly significantly reduce the need for such a fuel intensive boost back.
Presumably this is dependent on whether they can be deployed whilst the stage is hypersonic?

I remember when they were first seen, someone posted this link, which I thought did a great job of explaining a bit about grid fin utility.
Shouldn't reality posts be in "Advanced concepts"?  --Nomadd

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