# ProjectBFR for Orbiter 2016

#### Axel

##### Drive Technician
Ok maybe we can solve this problem in the future or we wait for another orbiter version with another ground detection system.
Another thing is, you wrote that for the Airfoils "a debug string is displayed". But i can not see the debug string when i press "A". But the aerodynamic is different when i press "A", that works. Standard config seems to be "airfoils on" at scenario start.
But the next thing are the aerodynamics itself of the ship, i find like the other orbinauts, its veeery veeeery hard to fly the ship in the atmosphere. But it is technicly a delta winged vessel, like the space shuttle, maybe a little bit smaller wings in relation to the hull, but longer and less empty weight. But the space shuttle is like a "beginner-plane", when i fly it after your BFR-addon.
Im not a beginner, i fly in orbiter since 2006! Its nearly impossible to fly a curve (around a airport) without wild shakings and rotations and without a crash . And KillRot was permanently on. Maybe the aerodynamics in your BFR.dll are wrong at some points. When not, Elon had better not changed the design of the bird, the first version (ITS) was a very nice lifting body, flying of this would be mutch easier, because more stable in the air and more lift.

I like the mesh, good job and keep up the work!
I hoped so mutch that somebody released a BFR/BFS-addon for orbiter, and you was the first!!!

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#### francisdrake

Don't blame Elon for the behaviour of this addon. The sluggish aerodynamic behaviour is purely mine.
I copied the aerodynamics from an old addon, a bi-conic CEV. The up-and-down pumping is probably because the lifting moment does not fit well to the drag and damping of the airfoil.
I could try to copy the Space Shuttle aerodynamics, but:
- The wings of the BFR are much smaller compared to the fuselage size.
- The Space Shuttle probably underperforms in the Martian atmosphere, leading to a high velocity impact on the surface.
You could try that by replacing the BFR with the Atlantis in the scenario file and do a Mars entry.

#### Axel

##### Drive Technician
Of course it is not Elon's fault. I think, the bi-conic CEV is to different in shape to the BFS. But the shape of the BFS is very similar to a normal rocket and the Skylon-addon from Inzane. The wings are even small or smaller there, but Skylon has at the nose and the rear very small aerodynamic stabilizers. A normal rocket has 4 wings, but these are smaller than the 2 of the BFS. The flying of a rocket and the Skylon is very easy compared to your BFS. So there must be a fault in your actual BFS-aerodynamic.

Yes i will test a mars entry with shuttle Atlantis. But i know, she will perform it great! I tryed in the past many mars entrys/landings with different types of vessels, you will wonder how well it is working, it's one of my favorite actions in orbiter, a really big fun of an important thing for the real future!.
The mars atmosphere is very thin at moment (until the year 2040 :thumbup but even very forgivable, because the lower mars gravitation of 0.38 G. You can fly mostly small winged vessels horizontal without a big altitude lost/descent rate, when you not fly slower than mach 3.

The solution is - we need somebody who has some experience in writing aerodynamics, maybe in spacecraft4 for testing. Many orbinauts did write very well aerodynamic configs for mutch more complicated vessels in shape.
We should contact they.

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#### Donamy

Donator
Beta Tester
The solution is - we need somebody who has some experience in writing aerodynamics, maybe in spacecraft4 for testing. Many orbinauts did write very well aerodynamic configs for much more complicated vessels in shape.
We should contact they.

Most of them have been taken back, to their home planets.

#### francisdrake

Udate Vers. 05 on the front page.
Used data from the MADV vehicle to improve the BFR aerodynamics.

With this version a controlled flip-over from aerodynamic to powered descent is possible, followed by a manual landing.

Major changes:
Copied the aerodynamic behaviour of the Space Shuttle, as this behaves well even in the Mars atmosphere. Adjusted it to the sizes and characteristic lengths of the BFR.
It is recommended to use KillRot and not to exceed 10x time acceleration during atmospheric flight.

The [A] key toggles between aerodynamic flight with the nose forward, and a reverse-attitude ballistic flight with the engines forward. Use KillRot to stabilize after flip-over. Gradually reduce engine power and righten up the vessel as it slows down.

#### Buck Rogers

great mod, like very much, as your other works! Could rant about loving 50's retro and the epitome of rocket design and despising the concept... I mean even if Musk has got pretty good at landing sticks upright there are so many negatives with such a design and then I see it as only a surface to orbit craft, interplanetary? How often must this thing refuel? Better one craft for one purpose for so many reasons, and the picture of the crane hauling everything high over the engines?! No no no, I think Musk just has a phallic obsession... OK enough ranting!

Concerning orientation at launch amend the scene file with this:

BFR:BFR
STATUS Landed Earth
POS -80.6208630 28.6270920
ALT 111.0
AROT 151.047 -8.224 -85.475

And I can tell you how I got this but not why it works? I assume it has to do with exact AROT figures! How is easy; Use scenario editor, location, change heading, exit, copy from current scene, paste, YGI.

All this brought me back to an old WIP of mine which I've got working with SC4 in Orbiter16.
Those your model also show a radar altitude above ground when landed? I haven't landed it yet, (I'll try the new update) and scenario editor doesn't work! On mine this altitude roughly corresponds to the COG which is where the 0 vector of the 3D model should be AFAIK. Has this changed, where is your 0 vector on this model?

I don't know if this is of interest; I noticed using SC4 configuration 0 (launch mode) it also falls through the ground but not with config 1!

I am also having problems with aerodynamics for a capsule, maybe you have a pointer for me?
... and finally (may as well ask while I'm here!) I may have used a texture of yours, if this is the case and I release it may I use it? With all due acknowledgements of course.

Looking forward to your further endeavors.

#### francisdrake

Hi Buck, that are a lot of topics.

The launch scenario is copied from the stock Atlantis scenario, after I got frustrated with the BFR always started toppled over, nose pointing to the ground. Only when providing an AROT vector it stayed upright.

Thanks for the tip on the scenario editor! I did not think of this. Will try it.

Radar altitude: This is correct, it shows the height of the mass center over ground.

Capsule aerodynamics:
The easiest way should be to define negative SetPitchMomentScale and SetBankMomentScale. This is what is use when the drogue chute is deployed of my Orion-MPCV, it gives a ballistic reentry. Note: The model must be upright (tailsitter, nose points to +z).
Code:
void CEV::SetConfig4_Chute(void)
{
SetSize (30);
SetEmptyMass (CM_DRYMASS);
SetTrimScale (0);
ClearAirfoilDefinitions();

SetCW (2, 2, 1, 1);
SetCrossSections (_V(26,26,2000));
SetRotDrag (_V(0.5,0.5,0.3));

SetPitchMomentScale(-2e-4);
SetBankMomentScale (-2e-4);

SetPMI (_V(9,9,3));

//	SetTouchdownPoints(_V(0,-5,-6.9),_V(-3,-2,-6.9),_V(3,-2,-6.9));
//	SetSurfaceFrictionCoeff (0.3, 0.3);

SetTouchdownPoints (tdvtx_geardown, ntdvtx_geardown);

ClearThrusterDefinitions();
mode = 4;
}

Feel free to re-use any of my textures.

#### Axel

##### Drive Technician
Ok flying is now better, more stable. I tested it even in earth atmosphere, before update it was nearly impossible. But please can you use the correct empty mass of 85 t instead the 135 t for the BFS ? I know you have involved the landing fuel, but we can not use the fuel when it is pure useless ship mass .

#### francisdrake

The mass of the spaceship is composed 85 ton dry mass + 50 ton default payload = 135 ton. This default value is assumed if no paylaod data are given.

You can override this by including a PAYLOAD line in the scenario file:
will set the payload to zero, leaving a dry mass of 85 ton.

#### Axel

##### Drive Technician
Hello all! I have hard worked, many many hours and i did find a solution for the BFR for standing right! :thumbup:
There are 2 ways: First one is very simple, you just open the file "Config/Vessels/BFR", and add simply this extra lines, here to see:

; === Configuration for the BFR ===

Classname = BFR ;new line to insert
Module = BFR

COG_OverGround = 30.0 ;new line to insert
TouchdownPoints = 0 -65 -25 -65 30 -25 65 30 -25 ;new line to insert

But important, you have to create a new scenario, where you have to add the BFR as new Vessel manualy via scenario editor, else the new values has no effekt. And its only for the spaceship, i did not yet test the booster. Now the BFR-spaceship stands right and you can land it, but the fuel has to be max 150 tonnes at touchdown, else you will fall under the mesh again. But when the ship is coming to stand really completly (0 m/s), maybe use Orbiter break keys, then you can refuel it as mutch you want.

---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
The second way, and which i like more, is to write a spacecraft3-config for it. This prevents better the sometimes "Nose down problem" and the ship stands a little bit more stable at the ground as a right tail sitter! The only disadvantage is, that you can not use the hover normaly, beacause in SC3 it fires all times down to the Y-axis.
At first, make a new file in "Config/Vessels/BFR-s" whit this lines:

ClassName = spacecraft3
Module = spacecraft3

TouchdownPoints = 0 -65 -25 -65 30 -25 65 30 -25

Then make a spacecraft3-file, in "Config/spacecraft/BFR-s" which involes this lines, its not the complet file, because francisdrake have allready the rest values, like aerodynamic, thrusters, docking, and exhausts. I had not yet enough time to explore that too. But i did some very succesfull tests with this, when i replaced the lines in another existing spacecraft3-file with this ones.

[CONFIG]
MESHNAME="BFR\BFR"
SIZE=19.6
EMPTY_MASS=85000
FUEL_MASS=1100000
MAIN_THRUST=14000000 ;7600000 main + 3400000 N hover
;HOVER_THRUST=3400000
RETRO_THRUST=300000
ATTITUDE_THRUST=300000
TRIM=0.05
ISP=3750 ;CH4-LOX
CW_Z_POS=0.2
CW_Z_NEG=0.5
CW_X=1.5
CW_Y=1.5
CROSS_SECTION=(234.8,389.1,68.2)
PMI=(78.2,82.1,10.7) ;Shuttle
COG=30
LAND_PT1=(0,-65,-25)
LAND_PT2=(-65,30,-25)
LAND_PT3=(65,30,-25)
PITCH_MOMENT_SCALE=0.00001
YAW_MOMENT_SCALE=0.00002
ROT_DRAG=(0.43,0.43,0.29)
FOCUS=0
VISIBLE=1
CAMERA=(0.00001,1.3,23.5)

[LANDING_GEAR]
WHEEL_FRICTION=0.05
BELLY_FRICTION=0.4
BRAKE_FORCE=2e5
SEQ=1

Ofcourse you have then to add this ship although as new vessel via scenario editor. Then test it out and mutch fun! :thumbup:

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#### fatcat

##### Member
Hey Brian,

Would you be able to work on the wonderful BFR model from francisdrake? You are a genius with the Falcons and Dragons.

#### Sbb1413

BrianJ, can you fulfil fatcat's wish?

#### BrianJ

Hey Brian,

Would you be able to work on the wonderful BFR model from francisdrake? You are a genius with the Falcons and Dragons.
Hi,
well, that's kind of up to francisdrake, if he wants me messing with his add-on. But it's a moot point at the moment - I'm still trying to get my Falcon Heavy to fly right (it's taking a while!). Need to get it finished before I tackle any other big projects.
Cheers,

Brian

#### francisdrake

Hi everybody! Brian, if you would like to pick up the BFR and continue the development, I would be honored. If someone would like the source code, I can publish it in a zip-file here.

My daytime work keeps me busy, and this will keep on for some time. So unfortunately I have no time for Orbiter development work.

My impression is, despite a lot of media coverage and the successful test hops, very few facts and figures are published on the actual BFR. So any performance figures will still educated guesses.

#### fatcat

##### Member
Yes, my post may have sounded impertinent to Sir Francis Drake. :embarrassed:
It was only that Francis had commented that passionate, skilled developers were welcome to get involved.
The correct response would be that I should develop my own ability.

#### BrianJ

Hi everybody! Brian, if you would like to pick up the BFR and continue the development, I would be honored. If someone would like the source code, I can publish it in a zip-file here.

My daytime work keeps me busy, and this will keep on for some time. So unfortunately I have no time for Orbiter development work.

My impression is, despite a lot of media coverage and the successful test hops, very few facts and figures are published on the actual BFR. So any performance figures will still educated guesses.
Hi,
I'd be delighted to get involved if I ever get the time! I'll certainly drop you a line when I get the chance. Yes, not much data on the BFR and the design seems to change quite regularly - not sure I'm up to date on the latest tweets from Mr.Musk anyway!
Cheers,
Brian

This is awesome

#### barrygolden

##### Well-known member
Hey this is a great start but needs an auto pilot and launch pad. Ans any way to get an auto landing his would be great

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