Solved Shuttles...
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Lt. Snakestrike
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Ok. Here'sthe thing about shuttles...
They're completely off balance.
And I do mean completely. Because basically if you balance it unloaded, the moment you add a payload, you're screwed. Balance it WITH payload, and it is a mess if unloaded.
That is, of course, if you are able to balance it at all. So now you got your balance basically via thrust differences on the side. But now your fuel empties too quick on one side... so it starts to turn one way, and when the fuel finishes it kicks over in a spin opposite to its undesired previous rotation. DEAD. What the hell?
But...
Unless you want to BUILD your shuttle in the exact format as the STS, you do have options.
The first, most obvious solution is to have boosters "above" and "below" the shuttle. This is above and below if the shuttle was in horizontal position. So basically both sides. Like so:
Now you may notice they are not symmetrical. So chances are the one runs out before the other. This could cause eitherundesired rotation or the out of fuel back- or forward flip, or both. They do not have equal motor distribution either, because the payload cavity might have a package that needs to be transported. That will require extra thrust to lift that side, thus the extra hawk. Because there is thrust on both sides, even if there is an imbalance it is already mostly cancelled out. Thus, correction is easy even without RCS, and without tons of control modules.
I'm this case it does run out at different times. There are two fixes: engine deactivation and fuel transfer. With the SCS here the upper booster burns longer than the lower booster. Thus when the lower booster runs out, it wants to tilt the shuttle forward, and the Titans do a real good job of it. But if I anticipate the cutoff, I can shut down one of the Titans. The outer Titan is farther from the centre of mass, so since it subsequently has the best leverage to flip my plane over, I chose that one. Problem solved:
I could also transfer some fuel from the upper booster to the lower one, but this is more uncertain and requires trial and error to perfect. It is also more sensitive to varying masses of payload. It can be done though.
Now, the lower booster easily falls away. The upper one has a tail fin to deal with. So, when it runs empty, you can either drop it and hope for the best... or sacrifice a little bit of Δv and be safe.
I personally opt for the second
For an STS type setup, fuel transfer is really your only solution and is true to the original STS also. You do not need much thrust from your shuttle unless you made it too big in comparison to the boosters. I'll make a separate post just for STS booster separation.
Balance the two sides separately. Treat it like two rockets next to each other rather than one. Then, get the TWR roughly equal on both sides. If necessary, make the booster bigger. If you can't, then make the shuttle lighter. Avoid thirsty engines on the shuttle if you can. But in SFS, generally you can't. Install at least one eco engine in it though, for orbital navigation.
The SCS cannot lift itself. The boosters do all the lifting. So they need to be big and strong. Fuel efficiency is for sissies The shuttle engines only ensure the boosters can focus on lifting rather than overcoming gravity. If by 20 to 25km you drop your first booster, you're probably home free.
But no matter what, expect the shuttle to make you work for your results...
They're completely off balance.
And I do mean completely. Because basically if you balance it unloaded, the moment you add a payload, you're screwed. Balance it WITH payload, and it is a mess if unloaded.
That is, of course, if you are able to balance it at all. So now you got your balance basically via thrust differences on the side. But now your fuel empties too quick on one side... so it starts to turn one way, and when the fuel finishes it kicks over in a spin opposite to its undesired previous rotation. DEAD. What the hell?
But...
Unless you want to BUILD your shuttle in the exact format as the STS, you do have options.
The first, most obvious solution is to have boosters "above" and "below" the shuttle. This is above and below if the shuttle was in horizontal position. So basically both sides. Like so:
Now you may notice they are not symmetrical. So chances are the one runs out before the other. This could cause eitherundesired rotation or the out of fuel back- or forward flip, or both. They do not have equal motor distribution either, because the payload cavity might have a package that needs to be transported. That will require extra thrust to lift that side, thus the extra hawk. Because there is thrust on both sides, even if there is an imbalance it is already mostly cancelled out. Thus, correction is easy even without RCS, and without tons of control modules.
I'm this case it does run out at different times. There are two fixes: engine deactivation and fuel transfer. With the SCS here the upper booster burns longer than the lower booster. Thus when the lower booster runs out, it wants to tilt the shuttle forward, and the Titans do a real good job of it. But if I anticipate the cutoff, I can shut down one of the Titans. The outer Titan is farther from the centre of mass, so since it subsequently has the best leverage to flip my plane over, I chose that one. Problem solved:
I could also transfer some fuel from the upper booster to the lower one, but this is more uncertain and requires trial and error to perfect. It is also more sensitive to varying masses of payload. It can be done though.
Now, the lower booster easily falls away. The upper one has a tail fin to deal with. So, when it runs empty, you can either drop it and hope for the best... or sacrifice a little bit of Δv and be safe.
I personally opt for the second
For an STS type setup, fuel transfer is really your only solution and is true to the original STS also. You do not need much thrust from your shuttle unless you made it too big in comparison to the boosters. I'll make a separate post just for STS booster separation.
Balance the two sides separately. Treat it like two rockets next to each other rather than one. Then, get the TWR roughly equal on both sides. If necessary, make the booster bigger. If you can't, then make the shuttle lighter. Avoid thirsty engines on the shuttle if you can. But in SFS, generally you can't. Install at least one eco engine in it though, for orbital navigation.
The SCS cannot lift itself. The boosters do all the lifting. So they need to be big and strong. Fuel efficiency is for sissies
The shuttle engines only ensure the boosters can focus on lifting rather than overcoming gravity. If by 20 to 25km you drop your first booster, you're probably home free.But no matter what, expect the shuttle to make you work for your results...
Lt. Snakestrike
The Kronian Serpent; Engineering Student
Head Professor
TEAM HAWK
Swingin' on a Star
Atlas
Under Pressure
Registered
Ok. Here'sthe thing about shuttles...
They're completely off balance.
And I do mean completely. Because basically if you balance it unloaded, the moment you add a payload, you're screwed. Balance it WITH payload, and it is a mess if unloaded.
That is, of course, if you are able to balance it at all. So now you got your balance basically via thrust differences on the side. But now your fuel empties too quick on one side... so it starts to turn one way, and when the fuel finishes it kicks over in a spin opposite to its undesired previous rotation. DEAD. What the hell?
But...
Unless you want to BUILD your shuttle in the exact format as the STS, you do have options.
The first, most obvious solution is to have boosters "above" and "below" the shuttle. This is above and below if the shuttle was in horizontal position. So basically both sides. Like so:
View attachment 18330
Now you may notice they are not symmetrical. So chances are the one runs out before the other. This could cause eitherundesired rotation or the out of fuel back- or forward flip, or both. They do not have equal motor distribution either, because the payload cavity might have a package that needs to be transported. That will require extra thrust to lift that side, thus the extra hawk. Because there is thrust on both sides, even if there is an imbalance it is already mostly cancelled out. Thus, correction is easy even without RCS, and without tons of control modules.
I'm this case it does run out at different times. There are two fixes: engine deactivation and fuel transfer. With the SCS here the upper booster burns longer than the lower booster. Thus when the lower booster runs out, it wants to tilt the shuttle forward, and the Titans do a real good job of it. But if I anticipate the cutoff, I can shut down one of the Titans. The outer Titan is farther from the centre of mass, so since it subsequently has the best leverage to flip my plane over, I chose that one. Problem solved:
View attachment 18329
I could also transfer some fuel from the upper booster to the lower one, but this is more uncertain and requires trial and error to perfect. It is also more sensitive to varying masses of payload. It can be done though.
Now, the lower booster easily falls away. The upper one has a tail fin to deal with. So, when it runs empty, you can either drop it and hope for the best... or sacrifice a little bit of Δv and be safe.
I personally opt for the second
For an STS type setup, fuel transfer is really your only solution and is true to the original STS also. You do not need much thrust from your shuttle unless you made it too big in comparison to the boosters. I'll make a separate post just for STS booster separation.
Balance the two sides separately. Treat it like two rockets next to each other rather than one. Then, get the TWR roughly equal on both sides. If necessary, make the booster bigger. If you can't, then make the shuttle lighter. Avoid thirsty engines on the shuttle if you can. But in SFS, generally you can't. Install at least one eco engine in it though, for orbital navigation.
The SCS cannot lift itself. The boosters do all the lifting. So they need to be big and strong. Fuel efficiency is for sissies The shuttle engines only ensure the boosters can focus on lifting rather than overcoming gravity. If by 20 to 25km you drop your first booster, you're probably home free.
But no matter what, expect the shuttle to make you work for your results...
They're completely off balance.
And I do mean completely. Because basically if you balance it unloaded, the moment you add a payload, you're screwed. Balance it WITH payload, and it is a mess if unloaded.
That is, of course, if you are able to balance it at all. So now you got your balance basically via thrust differences on the side. But now your fuel empties too quick on one side... so it starts to turn one way, and when the fuel finishes it kicks over in a spin opposite to its undesired previous rotation. DEAD. What the hell?
But...
Unless you want to BUILD your shuttle in the exact format as the STS, you do have options.
The first, most obvious solution is to have boosters "above" and "below" the shuttle. This is above and below if the shuttle was in horizontal position. So basically both sides. Like so:
View attachment 18330
Now you may notice they are not symmetrical. So chances are the one runs out before the other. This could cause eitherundesired rotation or the out of fuel back- or forward flip, or both. They do not have equal motor distribution either, because the payload cavity might have a package that needs to be transported. That will require extra thrust to lift that side, thus the extra hawk. Because there is thrust on both sides, even if there is an imbalance it is already mostly cancelled out. Thus, correction is easy even without RCS, and without tons of control modules.
I'm this case it does run out at different times. There are two fixes: engine deactivation and fuel transfer. With the SCS here the upper booster burns longer than the lower booster. Thus when the lower booster runs out, it wants to tilt the shuttle forward, and the Titans do a real good job of it. But if I anticipate the cutoff, I can shut down one of the Titans. The outer Titan is farther from the centre of mass, so since it subsequently has the best leverage to flip my plane over, I chose that one. Problem solved:
View attachment 18329
I could also transfer some fuel from the upper booster to the lower one, but this is more uncertain and requires trial and error to perfect. It is also more sensitive to varying masses of payload. It can be done though.
Now, the lower booster easily falls away. The upper one has a tail fin to deal with. So, when it runs empty, you can either drop it and hope for the best... or sacrifice a little bit of Δv and be safe.
I personally opt for the second
For an STS type setup, fuel transfer is really your only solution and is true to the original STS also. You do not need much thrust from your shuttle unless you made it too big in comparison to the boosters. I'll make a separate post just for STS booster separation.
Balance the two sides separately. Treat it like two rockets next to each other rather than one. Then, get the TWR roughly equal on both sides. If necessary, make the booster bigger. If you can't, then make the shuttle lighter. Avoid thirsty engines on the shuttle if you can. But in SFS, generally you can't. Install at least one eco engine in it though, for orbital navigation.
The SCS cannot lift itself. The boosters do all the lifting. So they need to be big and strong. Fuel efficiency is for sissies
The shuttle engines only ensure the boosters can focus on lifting rather than overcoming gravity. If by 20 to 25km you drop your first booster, you're probably home free.But no matter what, expect the shuttle to make you work for your results...
T
I drop the upper booster only after shutting down the throttle. I found the SCS Δ4 to not need fuel transfer. The Δ2 could not do without it, a weakness it inherited from the Γ Series.
With th SCS, loaded or unloaded, I simply shut off the topmost Titan as the lower booster runs dry. Simple. The rest is amazingly balanced.
With th SCS, loaded or unloaded, I simply shut off the topmost Titan as the lower booster runs dry. Simple. The rest is amazingly balanced.
Lt. Snakestrike
The Kronian Serpent; Engineering Student
Head Professor
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Yes that is what made the fuel transfer necessary. I needed the Titans for longer. So I used to transfer to the lower booster from launch until it ran out. I deactivated the hawks at 6000m and rotated my craft into more of a bow at 9000km. Before that I pointed nearly straight up. Then I would drop the lower booster, deactivate the upper Titan, and activate fuel transfer upwards until it ran out. Then I'd shut down, separate the top booster and continue to orbit.
A tight schedule...
A tight schedule...
Lt. Snakestrike
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If course the STS is in reality far better balanced since they angle the RS-25 engines to compensate for the unbalanced thrust profile by pointing it straight through the centre of thrust. The only way to do that here is .bp editing...
https://jmnet.one/sfs/forum/index.php?threads/sts-1-1-scale.2559/
https://jmnet.one/sfs/forum/index.php?threads/sts-1-1-scale.2559/
Pink
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Another thing to do, If you can't balance your Shuttle at all, is hidden engines.
For example, to make the Buran (the Soviet Space Shuttle), I originally I stalled to Hawks on the booster and two Titans on the Core (Energia). But Cosmo said: "No, Two Frontiers for the Energía, a single Titan for the Boosters." Okay.
And the other problem, is that, unlike the American STS, whose Main Engines are installed on the Shuttle, on the Buran they are installed on the Energia. The Buran does not have Main Engines, So you can't use them to balance the Shuttle like you do on the STS. Okay.
So I ended up with this:
How can that thing fly straight?
Well, I hided two Titan Engines on the left side of the Fairing (wich represents the Energía core) they are up enough So their flames aren't visible.
Now, that fixed the problem without payload, but what If you Add a 110 tons payload... Well, the two Titans are not gonna be able to balance the ship after the booster Separation... I would have to disable One of the Frontiers on the Energia to Compensate, and that would be unreallistic....
So what I did was stick a small Broadsword engine aiming sideways inside the Energia (you can see Its flame just where the Energia's tip begins). Its thrust Its enough to Compensate the unbalance And all this Its Done without .bp edit.
For example, to make the Buran (the Soviet Space Shuttle), I originally I stalled to Hawks on the booster and two Titans on the Core (Energia). But Cosmo said: "No, Two Frontiers for the Energía, a single Titan for the Boosters." Okay.
And the other problem, is that, unlike the American STS, whose Main Engines are installed on the Shuttle, on the Buran they are installed on the Energia. The Buran does not have Main Engines, So you can't use them to balance the Shuttle like you do on the STS. Okay.
So I ended up with this:
How can that thing fly straight?
Well, I hided two Titan Engines on the left side of the Fairing (wich represents the Energía core) they are up enough So their flames aren't visible.
Now, that fixed the problem without payload, but what If you Add a 110 tons payload... Well, the two Titans are not gonna be able to balance the ship after the booster Separation... I would have to disable One of the Frontiers on the Energia to Compensate, and that would be unreallistic....
So what I did was stick a small Broadsword engine aiming sideways inside the Energia (you can see Its flame just where the Energia's tip begins). Its thrust Its enough to Compensate the unbalance
And all this Its Done without .bp edit.