OHM Falcon9 for Orbiter2016

[BrianJ]

....but I was wondering how @BrianJ managed to get the autopilot so incredible accurate (I mean it is doing the same burns at the same time as the original)? Did you just reverse-engineer the original SpaceX one from videos, or did you have some better source?

Thanks. I guess my "solution" to the problem of landing the 1st stage back on the ground has gradually converged towards the SpaceX solution, which is no doubt close to optimal.

Since SpaceX have not been forthcoming with much hard info about the specs and functions of the Falcon9, I have relied on estimated data from Spaceflight101 (which concurs with most other websites) and comments dropped at press conferences etc., as well as watching the launch videos.

Apart from that, this old 1962 Ministry of Aviation paper "Minimum Energy Ballistic Trajectories Over A Non-Rotating Earth", was a help figuring the boostback flight vector.

The rest of it is put together from whatever I still remember from High School maths and physics :-D

Watching the SAOCOM launch video, I note the 1st stage came down a bit slower than the add-on, and the upper stage burned a bit longer, but otherwise the timings are pretty close. Which is nice

Cheers,
BrianJ

 

[ZacharyS41]

While launching from LC-39A, when the water deluge starts at T-10 seconds, the spray seems to be not in line with the rainbirds. Is there a reason why this happens?

The SLC-40 pad in Canaveral and SLC-4E pad in Vandenberg are okay, but this one is catching my eye every time.

 

[BrianJ]

Hi,
it looks ok to me - could you run a scenario where the bug happens, exit and post your "current_state.scn" and orbiter.log.

Water deluge is generated from the "Strongback" vessel, whereas the "rainbirds" (didn't know they were called that are part of the LC39A pad - so it's possible the "Strongback" has moved relative to the pad somehow?

Many thanks,
BrianJ

 

[ZacharyS41]

Brian, I actually changed the coordinates of LC-39A (Strongback) to match the ones listed in the General SpaceX Map: https://www.google.com/maps/d/viewer?mid=1wvgFIPuOmI8da9EIB88tHo9vamo

Instead of 28.608284 N, 80.6041192 W, I made it 28.6083065 N, 80.6041122 W.

 

[BrianJ]

Brian, I actually changed the coordinates of LC-39A (Strongback) to match the ones listed in the General SpaceX Map: https://www.google.com/maps/d/viewer?mid=1wvgFIPuOmI8da9EIB88tHo9vamo

Instead of 28.608284 N, 80.6041192 W, I made it 28.6083065 N, 80.6041122 W.

Ah, ok. You could either:
Use the original scenario pos parameters for the Strongback.
or
Move the LC39A hardstand mesh (which may then be out of aligment with surface tiles). To do that, you need to edit Config/Earth/BaseSpaceX/Canaveral.cfg


Cheers,
Brian

 

[pappy2]

If you download Kyle's SpaceX Mission Package, it includes an IRL layout of LZ-1. Should you download BrianJ's addon and then Kyle's addon, the latter's version will overwrite the former.

I have a problem with the latest updates to the launch of FALCON9: SAOCOM 1A.

 

[BrianJ]

I have a problem with the latest updates to the launch of FALCON9: SAOCOM 1A.

Hi,
this should really go in the SpaceX Mission Package thread ;-)

But, yes, the old LZ1 position doesn't quite match the new tiles.

You can use this for your LZ1 scenario entry...

LZ1:Falcon9R_V12\landingpad
  STATUS Landed Earth
  POS -80.5430200 28.4857580
  HEADING 180.00
  ALT 0.418
  AROT -118.158 -4.495 171.671
  AFCMODE 7
  NAVFREQ 0 0
  PADVIS 1
 END

Note: Using the "PADVIS 1" makes the mesh invisible, which I prefer with the new tiles.


Cheers,
BrianJ

 

[pappy2]

Everything is back in order now

thanks Brian

 

[ZacharyS41]

BrianJ, I've seen that during the boostback burn, the 1-3-1 engine sequence is used in which the center engine ignites first before the other two start up, and at the end, the center engine stays on for a couple seconds.

However, SpaceX uses this same engine sequence for the reentry burn and several hoverslam landing burns.

Is it possible to implement this to the Falcon9 addon?

 

[Kyle]

I've already updated those scenarios to account for BrianJ's most recent F9/LC-39A/LZ-1 updates. Will upload soon.

 

[BrianJ]

BrianJ, I've seen that during the boostback burn, the 1-3-1 engine sequence is used in which the center engine ignites first before the other two start up, and at the end, the center engine stays on for a couple seconds.

However, SpaceX uses this same engine sequence for the reentry burn and several hoverslam landing burns.

Is it possible to implement this to the Falcon9 addon?

I'll have a look at implementing that for the reentry burn,next update - but landing burn as well? Did they ever use 3 engines for landing? (Any video?)
Cheers,
BrianJ

 

[Kyle]

I'll have a look at implementing that for the reentry burn,next update - but landing burn as well? Did they ever use 3 engines for landing? (Any video?)
Cheers,
BrianJ

Yes, most of the EDL landings, as I understand it, feature a 3-engine landing burns.

 

[ZacharyS41]

There was the Falcon Heavy Test Flight when the side boosters landed at Cape Canaveral. They used the 1-3-1 engine sequence.

 

[BrianJ]

There was the Falcon Heavy Test Flight when the side boosters landed at Cape Canaveral. They used the 1-3-1 engine sequence.

Oh yes. The cheering at the end of that video still makes me smile


I don't know if I will be able to do that for the final landing burn - I had a shorter "hoverslam" style burn in a previous version, but couldn't get reasonable targeting accuracy - I'll have a think about that.
Cheers,
Brian

 

[ZacharyS41]

BrianJ,

On the Strongback (LC-39A) vessel, is it possible for the two rainbirds on the north side of the pad to activate at T-10 seconds alongside the other rainbirds, or are they just there for cosmetic reasons?

 

[BrianJ]

BrianJ,

On the Strongback (LC-39A) vessel, is it possible for the two rainbirds on the north side of the pad to activate at T-10 seconds alongside the other rainbirds, or are they just there for cosmetic reasons?

Hi, no, I don't think I gave the end ones any particle streams.

 

[ZacharyS41]

Hi, no, I don't think I gave the end ones any particle streams.

I understand that, but my question was if you could add those streams in the next update.

 

[BrianJ]

Patch with new LC39-A Strongback module, extra water deluge.
Unzip into Orbiter folder as usual.
View attachment lc39a_rainbird_patch_181206.zip

 

[Donamy]

deleted.

 

[BrianJ]

Thanks Don, got em