Project Updated SLS for Orbiter 2016 (and 2010)

Urwumpe · Oct 31, 2016

Code:

rbody	0xcdcdcdcd	 void *
base	0xcdcdcdcd 	void *
port 	        -842150451	        int
status	-842150451 	int

Those are all uninitialized variables.

gattispilot · Oct 31, 2016

Thanks

I thought so. But haven't found in the ssu crawler code where they are initialized

I am using the crawler.cpp and crawler.h

Urwumpe · Oct 31, 2016

gattispilot said:
Thanks

I thought so. But haven't found in the ssu crawler code where they are initialized

I am using the crawler.cpp and crawler.h

Don't ask me. I just see the code for the first time in 2016. :lol:

I can only tell by the pain in the left knee, that using "vs" without properly initializing the structure before calling GetStatusEx (especially the flag word, which contains some special kind of garbage) will have interesting results.

gattispilot · Nov 1, 2016

Ok. Well then I may do some research to see what they should be so I can initialize them.

On that subject is there a tool/app to show if a variable is initialized. I guess one could find the variable in the H and see if initialize in the cpp

---------- Post added at 05:43 PM ---------- Previous post was at 08:41 AM ----------

Ok I added this and now debug works great.

Code:

	memset(&vs, 0, sizeof(vs));
	vs.version = 2;

So now the next issue. The touchdown points. It calculates the new Y to be .01
so the touchdown points are set at

Code:

	SetTouchdownPoints(_V(0, .01, 20.0), _V(-15, .01, -20.0), _V(15, .01, -20.0));;

Now the crawler just rotates around
orginal touchdown.

Code:

	SetTouchdownPoints(_V(0, .001, 20), _V(-15, .001, -20), _V(15, .001, -20));;

Code:

bool SLSCRAWLER::UpdateTouchdownPoints(const VECTOR3 &relPos)
{
	double front_dist, back_dist;
	double dist = length(relPos);
	double dCos = cos(lastHead);

	front_dist = dist - 20.0*abs(dCos);
	back_dist = dist + 20.0*abs(dCos);
//	sprintf(oapiDebugString(), "dist %2.2f  frtdist %2.2fbackdist %2.2f ", dist, front_dist, back_dist);

	// ramp to LC39 starts 390 m from pad and ends 131.5 m from pad
	if (front_dist < LC39_RAMP_START && abs(relPos.x)<10.0)
	{
		double front_dist2 = dist - (FWD_DRIVETRACK_Z_OFFSET - 5.723)*abs(dCos);
		double back_dist2 = dist - (REAR_DRIVETRACK_Z_OFFSET - 5.723)*abs(dCos);

		double front_height = CalcRampHeight(front_dist);
		double back_height = CalcRampHeight(back_dist);
		double front_height2 = CalcRampHeight(front_dist2);
		double back_height2 = CalcRampHeight(back_dist2);

		double fwdAngle = atan((front_height - front_height2) / (front_dist2 - front_dist));
		double backAngle = atan((back_height2 - back_height) / (back_dist - back_dist2));
		double fwd_rot_anim_pos = fwdAngle / (20 * RAD);
		double back_rot_anim_pos = backAngle / (20 * RAD);
		if (dCos<0.0) {
			fwd_rot_anim_pos = -fwd_rot_anim_pos;
			back_rot_anim_pos = -back_rot_anim_pos;
		}

		// needed to prevent treads from appearing to sink into lover segment of ramp
		//front_height += range(0.0, (front_dist-131.5)*(0.4/(395.0-131.5)), 0.5);
		//back_height += range(0.0, (back_dist-131.5)*(0.4/(395.0-131.5)), 0.5);

		curFrontHeight = front_height;
		curBackHeight = back_height2;
		curFrontAngle = fwdAngle;
		curBackAngle = backAngle;

		UpdateTouchdownPoints();

		return true;
	}
	else {
		curFrontHeight = curBackHeight = 0.01;
		curFrontAngle = curBackAngle = 0.0;
		UpdateTouchdownPoints();
	}
	return false;
}

void SLSCRAWLER::UpdateTouchdownPoints() const
{
	double dCos = cos(lastHead);
	//unsigned short usAftIndex, usFwdIndex; // indicates which tracks are at 'aft' of crawler

	double fwd_rot_anim_pos = curFrontAngle / (20 * RAD);
	double back_rot_anim_pos = curBackAngle / (20 * RAD);
	if (dCos<0.0) {
		fwd_rot_anim_pos = -fwd_rot_anim_pos;
		back_rot_anim_pos = -back_rot_anim_pos;
	}


	double newytouch = (jackHeight + curFrontHeight);
	sprintf(oapiDebugString(), "xdf %2.2f ", newytouch);
	SetTouchdownPoints(_V(0, jackHeight + curFrontHeight, 20.0), _V(-15, jackHeight + curFrontHeight, -20.0), _V(15, jackHeight + curFrontHeight, -20.0));;

	
}

Now the crawler spins around. CAn not kill the rotation

---------- Post added at 06:01 PM ---------- Previous post was at 05:43 PM ----------

touchdown points are good in 2010

---------- Post added 11-01-16 at 07:17 AM ---------- Previous post was 10-31-16 at 06:01 PM ----------

Ok. A couple of issues. This is the launchpad39 mesh.

[/URL][/IMG]

[/URL][/IMG]

It needs to be redone for the crawler to work. 1 it is too short and the hole in the center is not wide enough. I can fix both

This is in 2010. I compiled in 2016 and just copied the dll over. Touchdown points work good. For some reason I done have Ultramath in my 2010 set up.

But it doesn't work in 2016 the crawler just spins

In 2010 the touchdown points are good but the thrust are different. I have noticed this on other vessels. The same thrust in 2010 is good but not in 2016.

Longjap · Nov 3, 2016

Hi everybody,

Tuesday! Sort of..

SLS Beta 0.3

Mostly fine-tuned in the fx and visuals department.

- Added more realistic mach effect.
- Tweaked the exhaust and contrails of the SRB's for better feel of power.
- Animated SSME exhaust flame fx for stage 1!
- Falling ice particles on take off.
- Added the Block 1b with Explorer Upper Stage and scenario with a 100 MT deadweight LEO insertion. Add your own payload for deep space exploration.
- Revamped EUS of gattispilot.
- Added a download for Orbiter 2010 specifically.

Download beta 0.3 for Orbiter 2016: https://www.dropbox.com/s/ji23814r0imd7r5/SLS_2016_BETA_0.3.zip?dl=0

Download beta 0.3 for Orbiter 2010: https://www.dropbox.com/s/uzo7x1ns5lz78fs/SLS_2016_BETA_0.3 - For 2010.zip?dl=0

Please let me know if there are any bugs.
Cheers.

Interceptor · Nov 3, 2016

Just tried this out,and it's really great,but on the Block b orion scenario the rocket never takes off after engaging the autopilot.BTW it's the orbiter 2010 version.

Longjap · Nov 3, 2016

Thanks Interceptor. Yep, same problem. I resolved it by clicking "update the vehicle" in the Multistage DMD and pressing "P" again. The Orion B wasn't supposed to be in the package yet. :lol:
Still working on it.

Interceptor · Nov 3, 2016

Thanks Longjap,the SLS rockets look beautiful,keep up the wonderful work.BTW love the LES.

romanasul · Nov 3, 2016

Longjap, the link to the SLS on the first page isn't working. Also, If you want to simulate a realistic isp curve for the RS-25 engines add the isp_sl=3590 under the [Stage] in order to simulate the 366 second surface isp for the engines. Set the burn time calculated for vacuum isp only and the isp_sl value will determine the curve based on atmospheric pressure.

Longjap · Nov 3, 2016

romanasul said:
Longjap, the link to the SLS on the first page isn't working. Also, If you want to simulate a realistic isp curve for the RS-25 engines add the isp_sl=3590 under the [Stage] in order to simulate the 366 second surface isp for the engines. Set the burn time calculated for vacuum isp only and the isp_sl value will determine the curve based on atmospheric pressure.

Thanks for your input romanasul! Something went wrong in the copy pasta with the links. Fixed it.

Yeah, I was wondering if orbiter calculated the changing thrust levels during ascent. So my naive thought was that maybe it only requires you to input the KNvac and Orbiter converts it first to sealevel and the less atmospheric pressure there is the more it transcends into KNvac. Forgive my hopefully understandable but non-scientific description. :lol:

So I guess this means I have to manually calculate the curves.
isp_sl=3590: What kind of unit is this? Seconds? Altitude?
If I change this will this mean a hard change from sealevel to vacuum thrust after 366 seconds? Or is more gradual?

romanasul · Nov 3, 2016

Longjap said:
Thanks for your input romanasul! Something went wrong in the copy pasta with the links. Fixed it.

Yeah, I was wondering if orbiter calculated the changing thrust levels during ascent. So my naive thought was that maybe it only requires you to input the KNvac and Orbiter converts it first to sealevel and the less atmospheric pressure there is the more it transcends into KNvac. Forgive my hopefully understandable but non-scientific description. :lol:

So I guess this means I have to manually calculate the curves.
isp_sl=3590: What kind of unit is this? Seconds? Altitude?
If I change this will this mean a hard change from sealevel to vacuum thrust after 366 seconds? Or is more gradual?

Unfortunately the Thrust variation due to pressure is not simulated by Multistage 2015, but the specific impulse variation is. You just need to input isp_sl= in m/s to whatever value the engine produces at sea level and multistage 2015 calculates a very realistic curve based on atmospheric pressure, starting from sea level of 101325 pascals. You do have to set the burn time to a value that specifies to the the vacuum specific impulse so for the SLS core you would set isp_sl=3590 for the RS-25 first stage. Burn time, based on usable fuel and thrust for 452.3 vac: 476.6.

9116000.375/4436=2055 kg/s fuel burn 979452.000/2055=476.6 seconds.
http://www.orbiter-forum.com/showthr...lse#post524854

Code:

[STAGE_1]
Height=63.720
Diameter=8.400
EmptyMass=85275.392 
FuelMass=979452.000 
Thrust=9116000.375
BurnTime=476.6
off=(0.000,0.000,4.700)
MeshName=SLS_2016\corerustET_1a_orion
eng_1=(-2.300,2.300,-32.208)
eng_2=(-2.300,-2.300,-32.208)
eng_3=(2.300,-2.300,-32.208)
eng_4=(2.300,2.300,-32.208)
eng_diameter=2.400
PITCHTHRUST=14193633.100 
YAWTHRUST=14193633.100 
speed=(0.000,0.000,-2.000)
ENG_PSTREAM1=engdetail_2
battery=1.500
Reignitable=1
Eng_tex=SLS_2016\SSME_Exhaust
Eng_pstream2=engdetail
Eng_dir=(0.000,0.000,1.000)
Module=Stage
Rot_speed=(0.000,0.000,0.000)
isp_sl=3590

gattispilot · Nov 4, 2016

Ok on the Crawler.

I have gotten mine to climb the ramp by adjusting the y values. I later looked at the SSU code and saw that the trucks rotate in the x direction for the ramp. So I got that.
BUT now the steering arm linkage are wrong. And it looks as if the rear/front set of truck raise up/down.

In some way would it not be easier to modified the ssu so that it will run on a new mesh?

But I haven't been able to compile it. Another option is to borrow the ssu crawler mesh and animations, code. Not sure how ethical that would be? Needlessly to say my fun factor is going fast

Longjap · Nov 6, 2016

Interceptor said:
Thanks Longjap,the SLS rockets look beautiful,keep up the wonderful work.BTW love the LES.

The LES is courtesy of francisdrake. I only applied some stickers on it.

I hope he or I can make the LES really work with Multistage someday.

romanasul said:
Unfortunately the Thrust variation due to pressure is not simulated by Multistage 2015, but the specific impulse variation is. You just need to input isp_sl= in m/s to whatever value the engine produces at sea level and multistage 2015 calculates a very realistic curve based on atmospheric pressure, starting from sea level of 101325 pascals. You do have to set the burn time to a value that specifies to the the vacuum specific impulse so for the SLS core you would set isp_sl=3590 for the RS-25 first stage. Burn time, based on usable fuel and thrust for 452.3 vac: 476.6.

9116000.375/4436=2055 kg/s fuel burn 979452.000/2055=476.6 seconds.
http://www.orbiter-forum.com/showthr...lse#post524854

Thanks! But the link to the thread doesn't work. I have used it and luckily there is no big difference in orbit insertion. It actually is a smoother ride. I'm trying to follow you on the math though.

What's the 4436 number?

gattispilot said:
Ok on the Crawler.

I have gotten mine to climb the ramp by adjusting the y values. I later looked at the SSU code and saw that the trucks rotate in the x direction for the ramp. So I got that.
BUT now the steering arm linkage are wrong. And it looks as if the rear/front set of truck raise up/down.

In some way would it not be easier to modified the ssu so that it will run on a new mesh?

But I haven't been able to compile it. Another option is to borrow the ssu crawler mesh and animations, code. Not sure how ethical that would be? Needlessly to say my fun factor is going fast

Hmm, seems like a lot of bumps in the road. I guess it's very complex all round to make it work. It sounds like the groups that are called for the animations are messed up?

It's sad if you give up all the work you've put in to it though. But I've read the SSU crew have plans to make an generic crawler for all kinds of LV. So if this becomes a reality I guess they don't mind if you'd use it and we use your mesh for example.

It might be better to build on top of that one indeed and you'd still have a use for all the time spend. But by all means, if you have no fun doing it, do something else you have fun doing.

I have some ideas and maybe you would like to help?

- The touchpoints of the tower, so it can be lowered and raised in 2016 but maybe that's already done while you were working on the crawler.
- The umbilical arms are not aligning perfectly to the SLS so I'm planning to shorten some a bit so it more or less fits.
- Question: Can I attach the SLS directly to the launchpad of the tower? I want the boosters to align with the connection on the pad.
- Make the umbilical arms swing away on launch, so basically press LAUNCH in SLS tower vessel display like you already made but now automatically, based on the command given in Multistage for launch. I'm not sure how to do this, it might need some communication between vessels, maybe you know a way to do this.

fred18 · Nov 6, 2016

Best for vessels inter-com is to use clbkgeneric. In ms2015 there are a couple of options already implemented for this kind of purposes: you can easily "extract": autopilot status (on or off), met and autopilot targets. In the doc it should be explained.

gattispilot · Nov 6, 2016

Longjap said:
Hmm, seems like a lot of bumps in the road. I guess it's very complex all round to make it work. It sounds like the groups that are called for the animations are messed up?

It's sad if you give up all the work you've put in to it though. But I've read the SSU crew have plans to make an generic crawler for all kinds of LV. So if this becomes a reality I guess they don't mind if you'd use it and we use your mesh for example.

It might be better to build on top of that one indeed and you'd still have a use for all the time spend. But by all means, if you have no fun doing it, do something else you have fun doing.

I have some ideas and maybe you would like to help?

- The touchpoints of the tower, so it can be lowered and raised in 2016 but maybe that's already done while you were working on the crawler.
- The umbilical arms are not aligning perfectly to the SLS so I'm planning to shorten some a bit so it more or less fits.
- Question: Can I attach the SLS directly to the launchpad of the tower? I want the boosters to align with the connection on the pad.
- Make the umbilical arms swing away on launch, so basically press LAUNCH in SLS tower vessel display like you already made but now automatically, based on the command given in Multistage for launch. I'm not sure how to do this, it might need some communication between vessels, maybe you know a way to do this.

I noticed the same issue with the ssu crawler. But I am getting her up the hill.:thumbup:

Yes you should be able to attach directly.

I think for 2016 a new code will need to be made. Something like press a key and now the pad is above the hill. So a new set of touchdown point that puts it on the hill and another on the ground.

Can you send a image of the umbilical cables. Then do move in and out.

I will need big help on the inter communication between vessels.

romanasul · Nov 6, 2016

Hey guys, I've been doing a bit of tinkering with Block I in order to make the performance of the engines and SRB to be closer to real life.

Code:

[BOOSTER_1]
N=1
MeshName=SLS_2016\Orange-booster_s
Height=53.900
Diameter=3.710
EmptyMass=86363.600
FuelMass=622727.300
Thrust=16363630.640
angle=0.000
off=(6.300,0.000,-0.300)
BurnTime=95.5
eng_1=(0.000,0.000,-28.000)
eng_diameter=0.010
ENG_PSTREAM1=srb_exhaust
Speed=(15.000,-4.000,0.000)
Rot_speed=(-0.200,-0.400,0.000)
Eng_tex=
Eng_pstream1=SRB_exhaust
Eng_pstream2=srb_exhaust_2
BurnDelay=0.000
Expbolts_pos=(6.450,0.000,19.000)
Expbolts_pstream=exbolt
Expbolts_anticipation=1.000
Curve_1=(0,76)
Curve_2=(2,100)
Curve_3=(4,97)
Curve_4=(6,98)
Curve_5=(22,96)
Curve_6=(52,75)
Curve_7=(76,80)
Curve_8=(110,70)
Curve_9=(120,13)

[BOOSTER_2]
N=1
Angle=0.000
Meshname=SLS_2016\Orange-booster_sl
Off=(-6.300,0.000,-0.300)
Height=53.900
Diameter=3.710
Thrust=16363630.640
EmptyMass=86363.600
FuelMass=622727.300
Burntime=95.5
Eng_diameter=0.010
Eng_tex=
Eng_pstream1=srb_exhaust
Eng_pstream2=srb_exhaust_2
Speed=(-15.000,-4.000,0.000)
Rot_speed=(-0.200,0.400,0.000)
Eng_1=(0.000,0.000,-28.000)
BurnDelay=0.000
Expbolts_pos=(-6.450,0.000,19.000)
Expbolts_pstream=exbolt
Expbolts_anticipation=1.000
Curve_1=(0,76)
Curve_2=(2,100)
Curve_3=(4,97)
Curve_4=(6,98)
Curve_5=(22,96)
Curve_6=(52,75)
Curve_7=(76,80)
Curve_8=(110,70)
Curve_9=(120,13)

[BOOSTER_3]
N=2
Angle=0.000
Meshname=SLS_2016\dummy
Off=(6.300,0.000,0.000)
Height=0.001
Diameter=0.001
Thrust=0.001
EmptyMass=0.100
FuelMass=0.100
Burntime=124.000
Eng_diameter=0.010
Eng_tex=
Eng_pstream1=diffuse_contrail
Eng_pstream2=emissive_contrail
Speed=(0.000,0.000,0.000)
Rot_speed=(0.000,0.000,0.000)
Eng_1=(0.000,0.000,-90.000)
Eng_2=(0.000,0.000,-90.000)  
BurnDelay=0.000

[BOOSTER_4]
N=3
Angle=90.000
Meshname=SLS_2016\dummy
Off=(2.200,0.000,25.000)
Height=0.001
Diameter=0.001
Thrust=0.001
EmptyMass=0.100
FuelMass=0.100
Burntime=15.000
BurnDelay=0.000
eng_1=(2.000,0.000,2.500)
Eng_diameter=0.000
Eng_tex=
Eng_pstream1=ice
Eng_pstream2=ice2
Speed=(0.000,0.000,0.000)
Rot_speed=(0.000,0.000,0.000)
Eng_2=(1.000,3.000,0.000)
Eng_3=(2.000,1.700,5.000)
Eng_4=(2.000,-0.200,-2.500)

[BOOSTER_5]
N=1
Angle=0.000
Meshname=SLS_2016\dummy
Off=(0.000,0.000,0.000)
Height=0.001
Diameter=0.001
Thrust=0.001
EmptyMass=0.100
FuelMass=0.100
Burntime=441.000
BurnDelay=0.000
Eng_diameter=0.000
Eng_tex=
Eng_pstream1=exhdetail
Eng_pstream2=
Speed=(0.000,0.000,0.000)
Rot_speed=(0.000,0.000,0.000)
eng_1=(-2.300,2.300,-48.000)
eng_2=(-2.300,-2.300,-48.000)
eng_3=(2.300,-2.300,-48.000)
eng_4=(2.300,2.300,-48.000)

[BOOSTER_6]
N=1
Angle=0.000
Meshname=SLS_2016\dummy
Off=(0.000,0.000,0.000)
Height=0.001
Diameter=0.001
Thrust=0.001
EmptyMass=0.100
FuelMass=0.100
Burntime=441.000
BurnDelay=0.000
Eng_diameter=0.000
Eng_tex=
Eng_pstream1=exhdetail2
Eng_pstream2=
Speed=(0.000,0.000,0.000)
Rot_speed=(0.000,0.000,0.000)
eng_1=(-2.300,2.300,-46.208)
eng_2=(-2.300,-2.300,-46.208)
eng_3=(2.300,-2.300,-46.208)
eng_4=(2.300,2.300,-46.208)

[STAGE_1]
Height=63.720
Diameter=8.400
EmptyMass=85275.392 
FuelMass=979452.000 
Thrust=9116000.375
BurnTime=476.6
off=(0.000,0.000,4.700)
MeshName=SLS_2016\corerustET_1a_orion
eng_1=(-2.300,2.300,-32.208)
eng_2=(-2.300,-2.300,-32.208)
eng_3=(2.300,-2.300,-32.208)
eng_4=(2.300,2.300,-32.208)
eng_diameter=2.400
PITCHTHRUST=14193633.100 
YAWTHRUST=14193633.100 
speed=(0.000,0.000,-2.000)
ENG_PSTREAM1=engdetail_2
battery=1.500
Reignitable=1
Eng_tex=SLS_2016\SSME_Exhaust
Eng_pstream2=engdetail
Eng_dir=(0.000,0.000,1.000)
Module=Stage
Rot_speed=(0.000,0.000,0.000)
isp_sl=3590

[STAGE_2]
MeshName=SLS_2016\SLS_ICPS2
Diameter=5.000
Height=13.700
EmptyMass=3765.000
FuelMass=26853.000
Thrust=110100.000
BurnTime=1113.4
ignite_delay=10.000
off=(0.000,0.000,42.950)
eng_1=(0.000,0.000,-6.500)
eng_diameter=2.700
ullage_thrust=10000.000
ullage_N=4
ullage_angle=-22.500
ullage_pos=(4.200,0.000,-10.700)
ullage_dir=(0.200,0.000,-1.000)
ullage_tex=Exhaust_atsme
ullage_length=5.000
ullage_diameter=1.000
ullage_anticipation=3.000
ullage_overlap=1.000
ullage_rectfactor=3.000
reignitable=1
Eng_tex=
Eng_pstream1=Engdetail_2
Eng_pstream2=Engdetail
Eng_dir=(0.000,0.000,1.000)
Module=Stage
Speed=(0.000,0.000,2.000)
Rot_speed=(0.000,0.000,0.000)

---------- Post added at 06:47 PM ---------- Previous post was at 06:40 PM ----------

I used this graph to predict the thrust Curve of the 5 Segment SRB: http://www.alternatewars.com/BBOW/Space/RSRM_STS-35.gif

I've also changed the specific impulse of the boosters in order to have an average between the sea level of 242 and vacuum of 269. For the RS-25 engines I have added an ISP curve and modified the burn time slightly in order to be consistent with the 452.3 sec vacuum impulse. For the RL-10B2 I have changed the Burn time in order to be at the 465.5 specific impulse with the fuel on board. I've also experimented with the Abside is order to try to get the cutoff range of periapse 50 and apoapse 1850 of the actual EM-1 mission but so far I've been unsuccessful. From what I read about EM-1 mission the RS-25 engines will throttle to 100 percent starting at -6 before liftoff and then to 109 so this can also be simulated as well. Let me know what you guys think, I would love to help in the project if possible.

fred18 · Nov 6, 2016

romanasul said:
I've also experimented with the Abside is order to try to get the cutoff range of periapse 50 and apoapse 1850 of the actual EM-1 mission but so far I've been unsuccessful.

the abside option could lead to less precision of the autopilot I know. try to make the last seconds of flight at 0.1x time acceleration to see if your precision improve.

romanasul said:
From what I read about EM-1 mission the RS-25 engines will throttle to 100 percent starting at -6 before liftoff and then to 109 so this can also be simulated as well. Let me know what you guys think, I would love to help in the project if possible.

I think that the 109 is actual the 100%, IIRC the RS25 engines were found capable of doing 104% of the design thrust safely and the 109%. But just as a convention the reference thrust remained the old design thrust and that's why they still call it 109. In reality the engines would go from 0 to 91.7% between t=-6 and t=0, then up to 100%. I think that with the engine calls of the guidance it will be not too difficult to implement this.

Good job guys :thumbup:

romanasul · Nov 6, 2016

Yes, 109 is at a thrust of around 2280 KN for the RS-25, I guess for SLS since the engines are expendable they're going to be run at this power level for the duration of the burn. For the abside I have yet to find a solution, I input 50 and 1850 for the p and a respectively and I've tried with absides ranging from 110 to 300 but every time the engines cut off the periapsis is too high.

Longjap · Nov 7, 2016

romanasul said:
Hey guys, I've been doing a bit of tinkering with Block I in order to make the performance of the engines and SRB to be closer to real life.

I used this graph to predict the thrust Curve of the 5 Segment SRB: http://www.alternatewars.com/BBOW/Space/RSRM_STS-35.gif

I've also changed the specific impulse of the boosters in order to have an average between the sea level of 242 and vacuum of 269. For the RS-25 engines I have added an ISP curve and modified the burn time slightly in order to be consistent with the 452.3 sec vacuum impulse. For the RL-10B2 I have changed the Burn time in order to be at the 465.5 specific impulse with the fuel on board. I've also experimented with the Abside is order to try to get the cutoff range of periapse 50 and apoapse 1850 of the actual EM-1 mission but so far I've been unsuccessful. From what I read about EM-1 mission the RS-25 engines will throttle to 100 percent starting at -6 before liftoff and then to 109 so this can also be simulated as well. Let me know what you guys think, I would love to help in the project if possible.

Sweet! Thanks for your help! I'll implement it in the next update. After I've read the mission plan I've been trying the same thing with the periapsis of 50 before. I've been unsuccessful also. Do you know any real life examples of the same kind of orbit insertion? I'm wondering how they achieve such an obit.

Your help is very welcome, join in! If you have more ideas or ways to improve let me know. I'm currently working on the Orion B. :thumbup:

fred18 · Nov 7, 2016

from NasaSpaceflight
https://www.nasaspaceflight.com/2016/07/mission-trajectory-sarafin-outlines-ride-uphill-em-1/

After Core Stage separation, both the spent stage and the mated Orion-ICPS stack will be in an elliptical Earth orbit with an apogee of about 975 nautical miles and a perigee of about 22 nautical miles.

At the first apogee, around forty-five to fifty minutes after liftoff, the ICPS will make its first burn to bring the perigee of the orbit up to 100 nautical miles.

Then around 90 minutes after launch as the stack completes its first orbit, the ICPS will perform a Trans-Lunar Injection (TLI) burn to send the vehicle towards the Moon.

It seems to me that they use just the core stage to get to that orbit. That's quite different from regular multistage rockets behaviour, it will be quite similar to shuttle actually. Anyway they do a small perigee raise burn at apogee. Try to input 80/1850 as autopilot targets and let it flight to 80, it should behave well in that case.

Project Updated SLS for Orbiter 2016 (and 2010)

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