Tuning your rocket engines effectively and using the right fuels can also greatly increase efficiency. My upper stages are generally always hydrolox as you can get away with using smaller engines in space plus they are a lot more efficient. Low throat size and as large as practically possible nozzle length when tuning engines for vacuum use will produce more thrust per unit of fuel used.
On the surface, you need raw power - energy dense fuels such as kerolox or methalox paired with a gas generator or full-flow staged rocket motor with plenty of thrust will make sure your rockets get off the ground. For this, high chamber pressure, large throat and a shorter nozzle will make your rocket more efficient at sea level. I tend to aim so that my first stage gets me at least 15-20 km ASL. Then a second ‘intermediate’ stage finishes ascension and circularises my Droo orbit. From there my third stage will do all my interplanetary manoeuvres then a final payload stage will have small low-powered engines and enough fuel to fine tune its orbit once it gets to its destination.
They’re in the same menu as staging. Should be a check icon then within that there is staging editor, AG list and a checklist of potential issues/errors with the craft.
I have been doing the Tydos moon missions in career mode. The hardest part is getting there in time as Droo can be in the wrong position for a simple transfer orbit burn once leaving Droo’s SOI. the mission timelines usually don’t allow for the time to do a chain of gravity assist manoeuvres to reduce delta-V budget unless of course the mission is accepted in a position where the planets are perfectly aligned. My current rocket for these missions at this point in time is a Saturn V style spacecraft. It is a beast - 106 m tall, 1200 tonnes with a total delta-V of around 11km/s and costs around $110M plus launch fees.
I have found if I do the mission in three steps, I tend to succeed. First step is to get into orbit around Droo, this is my “parking orbit” which is around 120-150 km ASL. At this point I wait until the craft is in a position to do a prograde ~1.4 km/s burn to escape Droo’s SOI. This gets me into a roughly circular orbit around Juno. Next I try to find the closest position to do another ~1.4-1.7 km/s burn. This can range from a purely prograde burn or incorporate some burn on the radial axis to pull the orbit path backward or forward so the apoapsis is closer to the SOI of Tydos. Then I fine tune the burn node so that the craft enters Tydos’ SOI and goes into Tydos’ atmosphere to perform an aerobraking manoeuvre. The orbit inside Tydos’ SOI should have a periapsis of around 2700 km meaning the craft will have an orbital velocity of 24000 m/s and aerobrake enough to reduce the orbit from hyperbolic to an apoapsis of between 150-300 Mm depending on how low into the atmosphere you go and also how un-aerodynamic your craft is.
When around Tydos your final stage should have plenty of delta-V because if it doesn’t, you won’t be making many orbital adjustments due to the intense gravitational pull of Tydos. Even a small orbital adjustment such as inclination of a few degrees can require hundreds of m/s of delta-V if your craft is close (inside the moons’ orbits) to Tydos.
@MarvinAeroDynamics unfortunately builds on Career Mode can’t use the tinker panel. But a lot of my Sandbox crafts do. Mainly drag and mass adjustments to parts. In a Sandbox game, I’m building a SSTO spaceplane and the amount of tinkering I’ve had to do to that for it to work properly is insane. I would like to build a vanilla one but I reckon it’s going to have to be twice the size due to having to carry an insane amount of fuel. It starts off with jet engines to get it high into the atmosphere then the rocket engines get it into orbit.
@MarvinAeroDynamics I tend to find parts create a lot of drag. If I have wings wrapped in fuel tanks, I tend to set the drag scale of the fuel tanks surrounding the wings to 20% in the tinker panel. I still want their physics to be included in the craft so I don’t want to completely eliminate the drag calculations of the wing fuel tanks. I might also reduce the wing’s drag scale to 80% if I want to be generous to my craft but not make it too unrealistically aerodynamic. I generally don’t touch the wings in the tinker panel though except for setting the sizes and offsets to specific figures that can’t be done with the wing resize nodes.
@MarvinAeroDynamics I’ve unlocked the afterburner, my formula for the Vizzy code is pretty good though still quite aggressive in the lower atmosphere but if I keep my speed down until about 10 km ASL then the plane flies pretty well. It seems to now naturally like flying at ~Mach 1.8 at 23-25 km ASL but this requires I run the engines at full throttle, using a lot of fuel. Wrapping the wings in fuel tanks makes the plane look nicer but the wings effectively have double the drag as wing physics are still calculated even if the wings are obscured by fuel tanks.
If I drop the throttle to about 92% (afterburner is still enabled) the fuel consumption is a lot lower and the plane flies pretty well and fast at around Mach 1.3 and around 19 km ASL. I’m trying to determine whether flying faster and higher at full throttle is more efficient than flying with slightly reduced throttle at slower speed and lower altitude.
I did a test flight last night and my plane can circumnavigate Droo at full throttle flying at an average of 28 km ASL and runs out of fuel just before getting back to Droo Space Centre where there is sufficient height to do a coasting (zero-throttle) descent and land on the runway. When the plane is loaded with fuel, it takes a lot of effort to stay above 25 km ASL but when there is about 10% of fuel left, the plane can comfortably fly at around 31 km ASL at a speed of around Mach 1.95.
I might try another test flight tonight where I run it at 92% throttle and find the height where the plane naturally likes to fly at this throttle setting and fly it until I run out of fuel. It will be interesting to see whether lower throttle is actually more efficient (considering the plane won’t have the airspeed to maintain stable flight at higher altitude). Being lower in the atmosphere will mean the engine will use more fuel but hopefully the reduced throttle and airspeed will compensate for this.
@MarvinAeroDynamics I’ve had a play with the engines. Aside from not having an afterburner, the engines do perform pretty well with your settings you suggested. But the craft barely just makes Mach 1.0 with your engine settings. I dare say it would go a lot faster with an afterburner. I’ve also shifted fuel around to different tanks so CoM is a lot more stable as the fuel gets used.
Top speed isn’t limited much by mass - the mass mainly affects the acceleration and handling of the craft. Drag is the main factor that limits top speed so engines with enough thrust to overcome drag is what will make my plane go faster. Though a lighter craft means less angle of attack to maintain horizontal flight which means slightly less drag. I looked at the performance analyser while tuning the engines and at 16.5 km ASL, Mach 1.5, the compression ratio that gives the most thrust is 3:1 although it’s not as efficient as a 10:1 compression ratio. There is a 10 kN difference in thrust between 130-120% size and a 3:1-10:1 compression ratio with no afterburner. I’m trying to get enough tech points to unlock the afterburner then I can properly try out your engine settings.
@MarvinAeroDynamics I haven’t unlocked the afterburner yet lol. But I do have the bypass ratio tech unlocked. I’ll have to plug those settings into the engines and see how well that works. I thought I had tuned the engines well as I’ve tuned them for optimum efficiency and thrust at 18.5 km ASL at Mach 1.5. I may have to play around with the settings more to try and find better efficiency ranges like you have done. Thanks so much and I’ll let you know how I go. With your thrust figures, I’m assuming that includes the afterburner being enabled?
@MarvinAeroDynamics the plane is basically finished. I have a payload deployment mechanism to install once I have the parts to construct it unlocked. I want the craft to have a cruise speed of around 500 m/s. I’m in the process now of modifying the rear control surfaces but the equation I’ve come up with seems to work well for the most part now. The payload deployment mechanism will be just behind the CoM. I’ve found the engines on my craft are really heavy and significantly shift the CoM backwards. I’ve played around with the order fuel tanks drain to help stabilise the CoM to CoL as well making sure the CoM doesn’t move too far back. I’m worried the CoM will be an issue once I install a payload deployer.
@MarvinAeroDynamics I have redone the Vizzy code and it seems to work better with air density as opposed to ASL. In terms of the game physics, I don’t think the game causes hot parts from supersonic speed friction to heat up air, thus changing its pressure. The hard part is finding the right equation to use in the Vizzy to set my Slider 4 input. I’m using a graphing app to plug in equations until I get a curve which suits my purposes. The equations I’m trying have Mach no. on the x-axis with pitch trim on the y-axis and atmospheric density is a variable in the equation. I’m getting some nice looking curves but it’s a matter of playing with the constants until the curve fits perfectly for my needs. Then there’s the adjustment of the stabilisers themselves until my inputs from the equation give the desired results.
@MarvinAeroDynamics thanks for the tips and sorry my terminology is a bit off. I have only just got back into building planes and stuff again. I’ll implement these changes into the Vissy. I just didn’t see Slider 4 changing while I was test flying my aircraft. I have put the program into the command pod and was testing it last night. I just need to play with the mathematical formula so the pitch trim happens appropriately. It seems to be very aggressive below 10 km ASL and at full throttle, the craft is supersonic before it gets to 4 km ASL. The program started working last night and for some reason it wasn’t working before which I why I posted this question in the first place. I might have to make the ASL variable in the Vissy based on air density instead as it’s the air density that is affecting how much lift the wings and stabilisers produce. Air density falloff is non-linear in relation to increasing altitude so I think that was a mistake using ASL as the second variable in my Vissy. It’s probably more of a thing of also tuning the stabilisers’ control surfaces to appropriately respond to Slider 4’s input as well.
@TomKerbal I don’t know how to but there are ways to decrease the roll and pitch amount for crafts that become touchier with increasing airspeed. I know some planes in real life (mainly fighters that travel at supersonic speeds) automatically decrease the amount control surfaces on the wings deflect to compensate for the increased effect they have at high speeds.
I found helicopters extremely hard to build in both Juno New Origins and SimplePlanes.
@TomKerbal know what exactly? Whether or not programs can be used in Career Mode or whether you load programs into the command pod or the parts they’re controlling?
I’m trying to make the tail fin of my aircraft (link in the post) automatically adjust in relation to the aircraft’s velocity and altitude. Being higher in the atmosphere requires more pitch trim and the faster the craft is moving requires less pitch trim. The program I’m trying to make should take both velocity and ASL into consideration and adjust the pitch trim (set on Slider 4) accordingly. I want to try and make my crafts so I don’t have to apply pitch trim on the pitch slider itself and also have pitch trim be automatically adjusted.
@Frolonov I tend to find a few (for me, I tend to use 3 or 4) smaller engines more efficient than one big one. Plus if you want to roll your craft in flight with the engine’s gimbal thrusting, one engine cannot roll the craft, whereas multiple, radially mounted engines, can. The cost is slightly higher initially but you’re also not needing as much fuel in your tanks which means a lighter rocket, and slightly higher TWR when pushing through Droo’s atmosphere when launching.
Tuning your rocket engines effectively and using the right fuels can also greatly increase efficiency. My upper stages are generally always hydrolox as you can get away with using smaller engines in space plus they are a lot more efficient. Low throat size and as large as practically possible nozzle length when tuning engines for vacuum use will produce more thrust per unit of fuel used.
+1 1.5 years agoOn the surface, you need raw power - energy dense fuels such as kerolox or methalox paired with a gas generator or full-flow staged rocket motor with plenty of thrust will make sure your rockets get off the ground. For this, high chamber pressure, large throat and a shorter nozzle will make your rocket more efficient at sea level. I tend to aim so that my first stage gets me at least 15-20 km ASL. Then a second ‘intermediate’ stage finishes ascension and circularises my Droo orbit. From there my third stage will do all my interplanetary manoeuvres then a final payload stage will have small low-powered engines and enough fuel to fine tune its orbit once it gets to its destination.
They’re in the same menu as staging. Should be a check icon then within that there is staging editor, AG list and a checklist of potential issues/errors with the craft.
1.5 years agoI’m hopeless at calculating for gravity assists. I don’t think my delta-V would be anywhere that low…
1.5 years agoI have been doing the Tydos moon missions in career mode. The hardest part is getting there in time as Droo can be in the wrong position for a simple transfer orbit burn once leaving Droo’s SOI. the mission timelines usually don’t allow for the time to do a chain of gravity assist manoeuvres to reduce delta-V budget unless of course the mission is accepted in a position where the planets are perfectly aligned. My current rocket for these missions at this point in time is a Saturn V style spacecraft. It is a beast - 106 m tall, 1200 tonnes with a total delta-V of around 11km/s and costs around $110M plus launch fees.
1.5 years agoI have found if I do the mission in three steps, I tend to succeed. First step is to get into orbit around Droo, this is my “parking orbit” which is around 120-150 km ASL. At this point I wait until the craft is in a position to do a prograde ~1.4 km/s burn to escape Droo’s SOI. This gets me into a roughly circular orbit around Juno. Next I try to find the closest position to do another ~1.4-1.7 km/s burn. This can range from a purely prograde burn or incorporate some burn on the radial axis to pull the orbit path backward or forward so the apoapsis is closer to the SOI of Tydos. Then I fine tune the burn node so that the craft enters Tydos’ SOI and goes into Tydos’ atmosphere to perform an aerobraking manoeuvre. The orbit inside Tydos’ SOI should have a periapsis of around 2700 km meaning the craft will have an orbital velocity of 24000 m/s and aerobrake enough to reduce the orbit from hyperbolic to an apoapsis of between 150-300 Mm depending on how low into the atmosphere you go and also how un-aerodynamic your craft is.
When around Tydos your final stage should have plenty of delta-V because if it doesn’t, you won’t be making many orbital adjustments due to the intense gravitational pull of Tydos. Even a small orbital adjustment such as inclination of a few degrees can require hundreds of m/s of delta-V if your craft is close (inside the moons’ orbits) to Tydos.
@MarvinAeroDynamics unfortunately builds on Career Mode can’t use the tinker panel. But a lot of my Sandbox crafts do. Mainly drag and mass adjustments to parts. In a Sandbox game, I’m building a SSTO spaceplane and the amount of tinkering I’ve had to do to that for it to work properly is insane. I would like to build a vanilla one but I reckon it’s going to have to be twice the size due to having to carry an insane amount of fuel. It starts off with jet engines to get it high into the atmosphere then the rocket engines get it into orbit.
1.6 years ago@MarvinAeroDynamics I tend to find parts create a lot of drag. If I have wings wrapped in fuel tanks, I tend to set the drag scale of the fuel tanks surrounding the wings to 20% in the tinker panel. I still want their physics to be included in the craft so I don’t want to completely eliminate the drag calculations of the wing fuel tanks. I might also reduce the wing’s drag scale to 80% if I want to be generous to my craft but not make it too unrealistically aerodynamic. I generally don’t touch the wings in the tinker panel though except for setting the sizes and offsets to specific figures that can’t be done with the wing resize nodes.
1.6 years ago@MarvinAeroDynamics I’ve unlocked the afterburner, my formula for the Vizzy code is pretty good though still quite aggressive in the lower atmosphere but if I keep my speed down until about 10 km ASL then the plane flies pretty well. It seems to now naturally like flying at ~Mach 1.8 at 23-25 km ASL but this requires I run the engines at full throttle, using a lot of fuel. Wrapping the wings in fuel tanks makes the plane look nicer but the wings effectively have double the drag as wing physics are still calculated even if the wings are obscured by fuel tanks.
If I drop the throttle to about 92% (afterburner is still enabled) the fuel consumption is a lot lower and the plane flies pretty well and fast at around Mach 1.3 and around 19 km ASL. I’m trying to determine whether flying faster and higher at full throttle is more efficient than flying with slightly reduced throttle at slower speed and lower altitude.
I did a test flight last night and my plane can circumnavigate Droo at full throttle flying at an average of 28 km ASL and runs out of fuel just before getting back to Droo Space Centre where there is sufficient height to do a coasting (zero-throttle) descent and land on the runway. When the plane is loaded with fuel, it takes a lot of effort to stay above 25 km ASL but when there is about 10% of fuel left, the plane can comfortably fly at around 31 km ASL at a speed of around Mach 1.95.
I might try another test flight tonight where I run it at 92% throttle and find the height where the plane naturally likes to fly at this throttle setting and fly it until I run out of fuel. It will be interesting to see whether lower throttle is actually more efficient (considering the plane won’t have the airspeed to maintain stable flight at higher altitude). Being lower in the atmosphere will mean the engine will use more fuel but hopefully the reduced throttle and airspeed will compensate for this.
1.6 years ago@MarvinAeroDynamics I’ve had a play with the engines. Aside from not having an afterburner, the engines do perform pretty well with your settings you suggested. But the craft barely just makes Mach 1.0 with your engine settings. I dare say it would go a lot faster with an afterburner. I’ve also shifted fuel around to different tanks so CoM is a lot more stable as the fuel gets used.
Top speed isn’t limited much by mass - the mass mainly affects the acceleration and handling of the craft. Drag is the main factor that limits top speed so engines with enough thrust to overcome drag is what will make my plane go faster. Though a lighter craft means less angle of attack to maintain horizontal flight which means slightly less drag. I looked at the performance analyser while tuning the engines and at 16.5 km ASL, Mach 1.5, the compression ratio that gives the most thrust is 3:1 although it’s not as efficient as a 10:1 compression ratio. There is a 10 kN difference in thrust between 130-120% size and a 3:1-10:1 compression ratio with no afterburner. I’m trying to get enough tech points to unlock the afterburner then I can properly try out your engine settings.
1.6 years ago@MarvinAeroDynamics I haven’t unlocked the afterburner yet lol. But I do have the bypass ratio tech unlocked. I’ll have to plug those settings into the engines and see how well that works. I thought I had tuned the engines well as I’ve tuned them for optimum efficiency and thrust at 18.5 km ASL at Mach 1.5. I may have to play around with the settings more to try and find better efficiency ranges like you have done. Thanks so much and I’ll let you know how I go. With your thrust figures, I’m assuming that includes the afterburner being enabled?
1.6 years ago@MarvinAeroDynamics the plane is basically finished. I have a payload deployment mechanism to install once I have the parts to construct it unlocked. I want the craft to have a cruise speed of around 500 m/s. I’m in the process now of modifying the rear control surfaces but the equation I’ve come up with seems to work well for the most part now. The payload deployment mechanism will be just behind the CoM. I’ve found the engines on my craft are really heavy and significantly shift the CoM backwards. I’ve played around with the order fuel tanks drain to help stabilise the CoM to CoL as well making sure the CoM doesn’t move too far back. I’m worried the CoM will be an issue once I install a payload deployer.
1.6 years ago@MarvinAeroDynamics I have redone the Vizzy code and it seems to work better with air density as opposed to ASL. In terms of the game physics, I don’t think the game causes hot parts from supersonic speed friction to heat up air, thus changing its pressure. The hard part is finding the right equation to use in the Vizzy to set my Slider 4 input. I’m using a graphing app to plug in equations until I get a curve which suits my purposes. The equations I’m trying have Mach no. on the x-axis with pitch trim on the y-axis and atmospheric density is a variable in the equation. I’m getting some nice looking curves but it’s a matter of playing with the constants until the curve fits perfectly for my needs. Then there’s the adjustment of the stabilisers themselves until my inputs from the equation give the desired results.
1.6 years ago@MarvinAeroDynamics thanks for the tips and sorry my terminology is a bit off. I have only just got back into building planes and stuff again. I’ll implement these changes into the Vissy. I just didn’t see Slider 4 changing while I was test flying my aircraft. I have put the program into the command pod and was testing it last night. I just need to play with the mathematical formula so the pitch trim happens appropriately. It seems to be very aggressive below 10 km ASL and at full throttle, the craft is supersonic before it gets to 4 km ASL. The program started working last night and for some reason it wasn’t working before which I why I posted this question in the first place. I might have to make the ASL variable in the Vissy based on air density instead as it’s the air density that is affecting how much lift the wings and stabilisers produce. Air density falloff is non-linear in relation to increasing altitude so I think that was a mistake using ASL as the second variable in my Vissy. It’s probably more of a thing of also tuning the stabilisers’ control surfaces to appropriately respond to Slider 4’s input as well.
1.6 years ago@TomKerbal I don’t know how to but there are ways to decrease the roll and pitch amount for crafts that become touchier with increasing airspeed. I know some planes in real life (mainly fighters that travel at supersonic speeds) automatically decrease the amount control surfaces on the wings deflect to compensate for the increased effect they have at high speeds.
I found helicopters extremely hard to build in both Juno New Origins and SimplePlanes.
1.6 years ago@TomKerbal know what exactly? Whether or not programs can be used in Career Mode or whether you load programs into the command pod or the parts they’re controlling?
I’m trying to make the tail fin of my aircraft (link in the post) automatically adjust in relation to the aircraft’s velocity and altitude. Being higher in the atmosphere requires more pitch trim and the faster the craft is moving requires less pitch trim. The program I’m trying to make should take both velocity and ASL into consideration and adjust the pitch trim (set on Slider 4) accordingly. I want to try and make my crafts so I don’t have to apply pitch trim on the pitch slider itself and also have pitch trim be automatically adjusted.
1.6 years ago@Frolonov I tend to find a few (for me, I tend to use 3 or 4) smaller engines more efficient than one big one. Plus if you want to roll your craft in flight with the engine’s gimbal thrusting, one engine cannot roll the craft, whereas multiple, radially mounted engines, can. The cost is slightly higher initially but you’re also not needing as much fuel in your tanks which means a lighter rocket, and slightly higher TWR when pushing through Droo’s atmosphere when launching.
1.6 years ago