OHM Falcon9R
- Thread starter OrbitHangar
- Start date
Where can I find it? OH?..
Donamy
Addon Developer
BrianJ
Addon Developer
Hey folks,
I just wanted to give a big shout of
"Thank You!"
to my friend IronRain who very kindly donated his time and engineering expertise to salvage the lost C++ code for the Falcon9R and FalconHeavy from my dead PC. Good job, dude! :thumbup:
Development of the Falcon9R and Heavy continues - "Grid Fins" and better autopilot are top of the list.
I have to say, the Orbiter online community is...something special.
Thanks
I just wanted to give a big shout of
"Thank You!"
to my friend IronRain who very kindly donated his time and engineering expertise to salvage the lost C++ code for the Falcon9R and FalconHeavy from my dead PC. Good job, dude! :thumbup:
Development of the Falcon9R and Heavy continues - "Grid Fins" and better autopilot are top of the list.
I have to say, the Orbiter online community is...something special.
Thanks
IronRain
The One and Only (AFAIK)
- Joined
- Oct 11, 2009
- Messages
- 3,484
- Reaction score
- 403
- Points
- 123
- Location
- Utrecht
- Website
- www.spaceflightnewsapi.net
You're very welcome! Glad I could help 
I'm looking forward to the future updates. This add-on is one of the most used launchers in my inventory.
I'm looking forward to the future updates. This add-on is one of the most used launchers in my inventory.
Definitely!
Kyle
Armchair Astronaut
You're the boss, IronRain!!
Cosmic Penguin
Geek Penguin in GTO
OK time for another multiple CTD problem....
Here's a scenario that I have made with the F9 carrying 2 satellites stacked together (obviously referring to a very recent launch....)
This is the configuration file for the satellites:
Every time I ran the scenario, it CTDs at the "loading f9.dll" point. Brian, can you check what's wrong with my scenario, or simply the current add-on does not support customized multiple payloads? :tiphat:
A similar question I have earlier, this time involving the use of Universal Cargo Deck, can be seen here: http://www.orbiter-forum.com/showthread.php?p=497598#post497598. I would be grateful if you can check out that problem too....
Here's a scenario that I have made with the F9 carrying 2 satellites stacked together (obviously referring to a very recent launch....
)
Code:
BEGIN_DESC
END_DESC
BEGIN_ENVIRONMENT
System Sol
Date MJD 57083.152778
END_ENVIRONMENT
BEGIN_FOCUS
Ship Falcon9
END_FOCUS
BEGIN_CAMERA
TARGET Falcon9
MODE Extern
POS 3.97 60.23 33.32
TRACKMODE Ground Earth
GROUNDLOCATION -80.57857 28.56044 12.26
FOV 40.00
END_CAMERA
BEGIN_HUD
TYPE Surface
END_HUD
BEGIN_MFD Left
TYPE Surface
SPDMODE 1
END_MFD
BEGIN_MFD Right
TYPE Map
REF Earth
BTARGET Habana
POS 0.00 0.00
END_MFD
BEGIN_SHIPS
SLC40:Falcon9R/slc40r
STATUS Landed Earth
POS -80.5771995 28.5619578
HEADING 10.00
AFCMODE 7
PRPLEVEL 0:1.000000 1:1.000000
NAVFREQ 0 0
PST 0.00 0.00
TOWER 3 0.00
END
Eutelsat115WB:Beta/Boeing702SP
STATUS Landed Earth
POS -80.5771995 28.5619578
HEADING 23.64
ATTACHED 0:0,Falcon9
AFCMODE 7
PRPLEVEL 0:1.00000
NAVFREQ 0 0
END
ABS-3A:Beta/Boeing702SP
STATUS Landed Earth
POS -80.5771995 28.5619578
HEADING 23.64
ATTACHED 0:1,Eutelsat115WB
AFCMODE 7
PRPLEVEL 0:1.00000
NAVFREQ 0 0
END
Falcon9:Falcon9R\f9
STATUS Landed Earth
POS -80.5771995 28.5619578
HEADING 10.00
ATTACHED 0:0,SLC40
AFCMODE 7
PRPLEVEL 0:1.000000 1:1.000000 2:1.000000
NAVFREQ 0 0
FAIRS 0
SOST 0 0 0 0 0
SOPR -0.5061 185000.0000 185000.0000 00000.0 120000.000 NULL
END
END_SHIPS
BEGIN_ExtMFD
ENDThis is the configuration file for the satellites:
Code:
; === Config file for Boeing702SP satellite ===
ClassName = Boeing702SP
MeshName = Falcon9R/cassiope
Size = 2.0
EnableFocus = TRUE
EnableXPDR = TRUE
XPDR = 500
Mass = 1000
TouchdownPoints = 0 -1 2 -2 -1 -2 2 -1 -2
Inertia = 2 2 1
CrossSections = 4 4 6
PropellantResource1 = 1000
ISP = 2000
MaxMainThrust = 50
MaxAttitudeThrust = 50
; === Attachment specs ===
BEGIN_ATTACHMENT
P 0 0 -1.22 0 0 -1 0 1 0 F9
C 0 0 1.22 0 0 1 0 1 0 Sat
END_ATTACHMENTEvery time I ran the scenario, it CTDs at the "loading f9.dll" point. Brian, can you check what's wrong with my scenario, or simply the current add-on does not support customized multiple payloads? :tiphat:
A similar question I have earlier, this time involving the use of Universal Cargo Deck, can be seen here: http://www.orbiter-forum.com/showthread.php?p=497598#post497598. I would be grateful if you can check out that problem too....
Interceptor
Well-known member
You da man IronRain!
BrianJ
Addon Developer
Hello
I'll have a look. It should be possible to attach anything to the Falcon9R.
Can you post your orbiter.log after a CTD? Cheers.
---------- Post added at 10:53 PM ---------- Previous post was at 10:28 PM ----------
I think the glitch is in the the ABS-3A vessel entry in the scenario. Try this:
EDIT: had a look at your post re:UniversalCargoDeck, but I've never really used it so I'm not sure if I can help.
If the CTD happens when you try to release the sats from UCD, it's probably UCD related. Save the scenario just before CTD and post it here, I'll have a look.
I'll have a look. It should be possible to attach anything to the Falcon9R.
Can you post your orbiter.log after a CTD? Cheers.
---------- Post added at 10:53 PM ---------- Previous post was at 10:28 PM ----------
I think the glitch is in the the ABS-3A vessel entry in the scenario. Try this:
Code:
ABS-3A:Beta/Boeing702SP
STATUS Landed Earth
POS -80.5771995 28.5619578
HEADING 23.64
[COLOR="Red"]ATTACHED 0:0,Eutelsat115WB[/COLOR]
AFCMODE 7
PRPLEVEL 0:1.00000
NAVFREQ 0 0
ENDEDIT: had a look at your post re:UniversalCargoDeck, but I've never really used it so I'm not sure if I can help.
If the CTD happens when you try to release the sats from UCD, it's probably UCD related. Save the scenario just before CTD and post it here, I'll have a look.
Last edited:
Cosmic Penguin
Geek Penguin in GTO
Hello
I'll have a look. It should be possible to attach anything to the Falcon9R.
Can you post your orbiter.log after a CTD? Cheers.
---------- Post added at 10:53 PM ---------- Previous post was at 10:28 PM ----------
I think the glitch is in the the ABS-3A vessel entry in the scenario. Try this:
Code:ABS-3A:Beta/Boeing702SP STATUS Landed Earth POS -80.5771995 28.5619578 HEADING 23.64 [COLOR="Red"]ATTACHED 0:0,Eutelsat115WB[/COLOR] AFCMODE 7 PRPLEVEL 0:1.00000 NAVFREQ 0 0 END
EDIT: had a look at your post re:UniversalCargoDeck, but I've never really used it so I'm not sure if I can help.
If the CTD happens when you try to release the sats from UCD, it's probably UCD related. Save the scenario just before CTD and post it here, I'll have a look.
OK thanks, it works! One problem though - I can't jettison the upper vessel from the lower one while both are still attached to the F9 2nd stage (heck I can't even separate the two AFTER I jettison the two together from the F9 - probably there are spacecraft configuration issues). Anyone knows how I can do it?
Pipcard
mikusingularity
How exactly does your add-on calculate the precise landing location and adjust accordingly to reach the target?
Donamy
Addon Developer
A magician never reveals his secrets.
Pipcard
mikusingularity
But I want to have reusability when I (eventually) make my M-III launch vehicle.
BrianJ
Addon Developer
No secrets - the C++ code is included in the add-on.
Here's a brief overview of my rather simple method - it's only a few hundred lines of code, after all.
1. Make an attitude control algorithm for the vessel, that can receive a "target flight vector" in local vessel frame, and slew the vessel to that attitude.Other algorithms will calculate the target flight vector (and set main engine throttle) and pass the target flight vector to the attitude control.
Split the task into sections:
2. Make a "boostback" burn to put the vessel on a ballistic trajectory to it's target.
How to find the flight vector?
There are an infinite number of possible ballistic trajectories from the vessel's current position to the target - I figured the "minimum energy ballistic trajectory" would be a logical choice - the less energy you put in, the less you have to take out later.
This handy and venerable document has the maths needed to calculate the vertical and tangential velocity, for a minimum energy ballistic trajectory from the vessel's current position to its target: http://naca.central.cranfield.ac.uk/reports/arc/cp/0604.pdf It only deals with a "non-rotating Earth" case, but it's fairly easy to compensate by adding a bit to your target's longitude, according to the flight time and Earth rotation rate.
You can find the direction of your tangential velocity by taking the cross product of your target's position vector and your position vector (global frame, rel.Earth), then taking the cross product of the result with your position vector again. Normalise the resulting vector to the tangential velocity as calculated above. Then normalise your position vector to the vertical velocity as calculated previously, and add it to your tangential velocity vector. Subtract your current velocity(global frame, rel.Earth) Rotate the result into local vessel frame. This is your target flight vector.
Burn main engines until the target flight vector gets real short, then switch off.
Note: you need to over burn a little so that you can reduce velocity, and hence range, during reentry. I managed this by setting a target altitude offset i.e. aiming for a point above the target itself (typically 3-8km). The offset is adjusted according to flight vector azimuth, excess fuel mass, final impact trajectory angle.
3. Turn the aft-end into the flight vector for reentry and landing.
4. Calculate the vessel's current range(distance it will travel before it hits the target's altitude, using a lower altitude offset than before) based on current altitude and velocity. This page has the necessary maths for calculating the range using a simple Stoke's(I think) drag term:
http://en.wikipedia.org/wiki/Trajec...rajectory_of_a_projectile_with_air_resistance
From the above, given your current altitude and vertical velocity, you can calculate the required tangential velocity to reach the target. From current vessel mass, thrust and pitch, you can calculate time required to burn to achieve required tangential velocity. Start burn when time required for burn is equal to current time until target altitude(plus a margin for safety). Eliminate cross range errors by rotating flight vector about axis orthogonal to airspeed vector and horizontal.
Stop burn when vessel range is equal/less than target range.
5. Repeat process at lower altitude using an even lower target altitude offset, and slightly modified drag term for denser atmosphere.
6. Eliminate trajectory errors by using lift during last bit of freefall. Rotate flight vector around axis orthogonal to current flight vector and vector from vessel to target.
7. Start landing burn at altitude determined by fuel reserves(plus an offset). Set thrust to reduce vertical velocity to ~zero by landing. Eliminate trajectory errors by rotating flight vector towards/away from target during descent.
8. Land softly as a feather.
Here's a brief overview of my rather simple method - it's only a few hundred lines of code, after all.
1. Make an attitude control algorithm for the vessel, that can receive a "target flight vector" in local vessel frame, and slew the vessel to that attitude.Other algorithms will calculate the target flight vector (and set main engine throttle) and pass the target flight vector to the attitude control.
Split the task into sections:
2. Make a "boostback" burn to put the vessel on a ballistic trajectory to it's target.
How to find the flight vector?
There are an infinite number of possible ballistic trajectories from the vessel's current position to the target - I figured the "minimum energy ballistic trajectory" would be a logical choice - the less energy you put in, the less you have to take out later.
This handy and venerable document has the maths needed to calculate the vertical and tangential velocity, for a minimum energy ballistic trajectory from the vessel's current position to its target: http://naca.central.cranfield.ac.uk/reports/arc/cp/0604.pdf It only deals with a "non-rotating Earth" case, but it's fairly easy to compensate by adding a bit to your target's longitude, according to the flight time and Earth rotation rate.
You can find the direction of your tangential velocity by taking the cross product of your target's position vector and your position vector (global frame, rel.Earth), then taking the cross product of the result with your position vector again. Normalise the resulting vector to the tangential velocity as calculated above. Then normalise your position vector to the vertical velocity as calculated previously, and add it to your tangential velocity vector. Subtract your current velocity(global frame, rel.Earth) Rotate the result into local vessel frame. This is your target flight vector.
Burn main engines until the target flight vector gets real short, then switch off.
Note: you need to over burn a little so that you can reduce velocity, and hence range, during reentry. I managed this by setting a target altitude offset i.e. aiming for a point above the target itself (typically 3-8km). The offset is adjusted according to flight vector azimuth, excess fuel mass, final impact trajectory angle.
3. Turn the aft-end into the flight vector for reentry and landing.
4. Calculate the vessel's current range(distance it will travel before it hits the target's altitude, using a lower altitude offset than before) based on current altitude and velocity. This page has the necessary maths for calculating the range using a simple Stoke's(I think) drag term:
http://en.wikipedia.org/wiki/Trajec...rajectory_of_a_projectile_with_air_resistance
From the above, given your current altitude and vertical velocity, you can calculate the required tangential velocity to reach the target. From current vessel mass, thrust and pitch, you can calculate time required to burn to achieve required tangential velocity. Start burn when time required for burn is equal to current time until target altitude(plus a margin for safety). Eliminate cross range errors by rotating flight vector about axis orthogonal to airspeed vector and horizontal.
Stop burn when vessel range is equal/less than target range.
5. Repeat process at lower altitude using an even lower target altitude offset, and slightly modified drag term for denser atmosphere.
6. Eliminate trajectory errors by using lift during last bit of freefall. Rotate flight vector around axis orthogonal to current flight vector and vector from vessel to target.
7. Start landing burn at altitude determined by fuel reserves(plus an offset). Set thrust to reduce vertical velocity to ~zero by landing. Eliminate trajectory errors by rotating flight vector towards/away from target during descent.
8. Land softly as a feather.
Pipcard
mikusingularity
Thank you very much for explaining your method.
Pipcard
mikusingularity
SpaceX claims that Falcon Heavy's LEO payload (53 tonnes, non-reusable) has a 4:1 ratio compared to Falcon 9 (13 tonnes, non-reusable).
But your simulated, non-reusable Falcon 9 actually has a 17-tonne capacity to LEO. I thought there was some secret as to how FH could've gotten that kind of ratio with F9, but no, the ratio is 3:1 as I would expect.
But your simulated, non-reusable Falcon 9 actually has a 17-tonne capacity to LEO. I thought there was some secret as to how FH could've gotten that kind of ratio with F9, but no, the ratio is 3:1 as I would expect.
BrianJ
Addon Developer
I seem to recall reading an interview with Elon Musk where he said the Falcon9 could actually lift 17T to LEO - but I certainly can't find the reference now. Maybe my Falcon9 is a trifle overpowered - I used the most reliable sources I could find on the web for the specs.
I recently found this paper:
http://www.sei.aero/eng/papers/uploads/archive/SpaceWorks VTVL Study - Release.pdf
which suggests the fly-back can be done with about 50% of the fuel that my method uses. It also gives an aproximate reentry thermal constraint, so now I can at least check how that stacks up against my simulation. Maybe I can use a bit more atmospheric drag to save fuel.
I recently found this paper:
http://www.sei.aero/eng/papers/uploads/archive/SpaceWorks VTVL Study - Release.pdf
which suggests the fly-back can be done with about 50% of the fuel that my method uses. It also gives an aproximate reentry thermal constraint, so now I can at least check how that stacks up against my simulation. Maybe I can use a bit more atmospheric drag to save fuel.
Kyle
Armchair Astronaut
17 tons to LEO sounds like it could be right with the new, slightly larger Falcon 9 that's due to launch later this year.
