Discussion SpaceX's Grasshopper RLV

[Arrowstar]

Hearing rumors that F9R flew today, 250m divert and was successful.

Did they attempt to soft land in the ocean?

 

[Hlynkacg]

Did they attempt to soft land in the ocean?

Yes.

From the other thread...

SpaceX's twitter account just reported that the first stage landed safely, roll and decent rates were in limits and the stage continued to transmit data after touchdown, but heavy seas have prevented recovery.

 

[Cosmic Penguin]

 

[MaverickSawyer]

Say WHAT? A kilometer? Wow, they're moving right along!

 

[Kyle]

I believe the goal is sub-orbital when they get to New Mexico, and I'd imagine that'll be sometime before we see the first F9R landing at Cape Canaveral.

 

[Kyle]

There was another test today, 1,000 meters with a new feature.

 

[PhantomCruiser]

Seems like the cows are getting accustomed to the noise.

 

[orb]

Whose idea was to put such a strange font in the rocket cam view?

Seems like the cows are getting accustomed to the noise.

Reaction of the cows:

- Yikes, something horrible is happening!
- Meh, it's just another rocket launch. Don't panic. Let's go to another part of the field to get a better view.​

 

[ISProgram]

I wonder if those grid fins might appear in the operational F9-R... :hmm:

---------- Post added 06-19-14 at 12:03 AM ---------- Previous post was 06-18-14 at 11:59 PM ----------

Seems like the cows are getting accustomed to the noise.

Well, the cows don't seem to think that... (NSF)

"Why yes, the engine tests are indeed quite loud and scary."

 

[Donamy]

I would assume so, ... they love to make me change the model.

 

[Thunder Chicken]

I think we'll definitely be seeing those in action on the high altitude / velocity tests and perhaps on the actual first stage. Grid fins are very effective at aerodynamic control at high supersonic velocities. This would provide a lot of control between staging and the inversion maneuver where it turns to a tail-first attitude.

 

[RisingFury]

How much drag do they provide? Can they substantially slow the stage down at high speeds?

 

[ISProgram]

How much drag do they provide? Can they substantially slow the stage down at high speeds?

Grid fins work well at subsonic and supersonic speeds, but are bad at transonic speeds.

Thus, it's good for control as the stage descends through the atmosphere. They don't need those nitrogen thrusters for roll control anymore, for example. As a matter of fact, I'm pretty sure using grid fin saves more weight than the nitrogen RCS...I think they are replacements...

To be exact, this was probably introduced so that they could achieve better accuracy and maneuverability when heading for a pinpoint landing at a landing pad.

In the video, it's interesting how the movement of the fins affect the stage's attitude.

 

[Andy44]

Ah, so now I understand after reading the video's description and watching the second half of the vid: The grid fins are at the front of the vehicle, and the landing legs won't be deployed until just before touchdown, which would prevent them from shuttlecocking. Very very cool.

Now all they need to do is figure out how to change the point of view for tailsitters, which all Orbiter developers know is the BIGGEST problem with this sort of thing...