Agathorn Posted January 27, 2014 Share Posted January 27, 2014 Man getting this first stage to re-enter, and land is so hard. I must have launched a hundred tests and have yet to recover one. Most burn up in the atmosphere re-entry. Link to comment Share on other sites More sharing options...
Scripto23 Posted January 27, 2014 Share Posted January 27, 2014 Man getting this first stage to re-enter, and land is so hard. I must have launched a hundred tests and have yet to recover one. Most burn up in the atmosphere re-entry.They burn up with the heatshield? I may not have fixed maxtemp for that that version on dropbox then. I'll upload an updated one now. It'll also have the RT code in it. I'm also having trouble landing that stage after atmospheric reentry. I've had to employ a small drogue shoot to flip the stage around so the engine can face the right way for the retrograde landing burn. Without that it's just too aerodynamically stable to flip by other means. Link to comment Share on other sites More sharing options...
HoneyFox Posted January 27, 2014 Share Posted January 27, 2014 They burn up with the heatshield? I may not have fixed maxtemp for that that version on dropbox then. I'll upload an updated one now. It'll also have the RT code in it. I'm also having trouble landing that stage after atmospheric reentry. I've had to employ a small drogue shoot to flip the stage around so the engine can face the right way for the retrograde landing burn. Without that it's just too aerodynamically stable to flip by other means.I don't have issue of aerodynamic stablility... my first stage reentry with retrograde automatically with no need of any chutes, air-brakes...The second stage is a bit tricky though. I installed that heat shield at the top of the second stage, and keep at prograde attitude before reentry, it works well. And after it reaches a quite low air speed, i disable three of these super draco engines, leaving only one to burn at max throttle. With some careful throttling it can flip to retrograde attitude without too much trouble. Then re-enable the rest three engines to slow down to land. Link to comment Share on other sites More sharing options...
Agathorn Posted January 27, 2014 Share Posted January 27, 2014 They burn up with the heatshield? I may not have fixed maxtemp for that that version on dropbox then. I'll upload an updated one now. It'll also have the RT code in it. I'm also having trouble landing that stage after atmospheric reentry. I've had to employ a small drogue shoot to flip the stage around so the engine can face the right way for the retrograde landing burn. Without that it's just too aerodynamically stable to flip by other means.I think it has a lot to do with finding the proper flight path, and re-entry corridor. I flip it around so its head first with the heatshield. The heatshield holds up just fine. Unfortunately the other bits on the first stage don't do so well, so things like the RCS ports and even sometimes the landing gear, blow up. I'm starting to think its actually easier to go back in engine first, even though that isn't how SpaceX shows it to be done. Link to comment Share on other sites More sharing options...
LazarusLuan Posted January 27, 2014 Author Share Posted January 27, 2014 I think it has a lot to do with finding the proper flight path, and re-entry corridor. I flip it around so its head first with the heatshield. The heatshield holds up just fine. Unfortunately the other bits on the first stage don't do so well, so things like the RCS ports and even sometimes the landing gear, blow up. I'm starting to think its actually easier to go back in engine first, even though that isn't how SpaceX shows it to be done.The first flight of the Falcon 9 v1.1 included a full test of bringing the first stage back through the atmosphere tail-first and using the Merlin 1Ds in a 3-across and then a 5x configuration to slow the vehicle to just under the speeds needed to keep the shockwave from becoming plasma, removing any need for ablative coatings or heat shields. This test worked perfectly, and the plan is to attempt a complete return of the first stage after the CRS-3 launch to the ISS in less than a month. I've thoroughly tested this reentry technique, and while it does reduce the total potential payload to orbit by about 30%, it works perfectly in KSP. I am currently in the middle of creating new demonstration videos for all the planned upcoming Falcon 9 and Falcon Heavy missions for SpaceX, which includes this reentry technique, and will be posting these up on my YouTube channel starting this week. Link to comment Share on other sites More sharing options...
TheDude Posted January 27, 2014 Share Posted January 27, 2014 Greetings,I'm having a problem with the interstage fairings not releasing when triggered. The fairing will kinda release and the second stage engine will fire but it all stays attached like it's connected with a giant rubber band. The first stange and fairing will flop around while the second stage drags it along. I was able to get around the problem by using 8 radialy mounted engines(I can't remember from what pack) instead of the Merlin 1D Vacuum Engine provided in the pack. While i"m thinking about it - Can you get rid of the "tit" on the second stage tank so other engines can be used? I've tried other engines, and they do mount, but the tit seems to interfere with the gimbal. On all engines I've tried the engine will fire but the gimbal will hard lock to one extreme which causes the second stage to spin wildly out of control.Best regards,The Dude Link to comment Share on other sites More sharing options...
Scripto23 Posted January 27, 2014 Share Posted January 27, 2014 The first flight of the Falcon 9 v1.1 included a full test of bringing the first stage back through the atmosphere tail-first and using the Merlin 1Ds in a 3-across and then a 5x configuration to slow the vehicle to just under the speeds needed to keep the shockwave from becoming plasma, removing any need for ablative coatings or heat shields. This test worked perfectly, and the plan is to attempt a complete return of the first stage after the CRS-3 launch to the ISS in less than a month. I've thoroughly tested this reentry technique, and while it does reduce the total potential payload to orbit by about 30%, it works perfectly in KSP. I am currently in the middle of creating new demonstration videos for all the planned upcoming Falcon 9 and Falcon Heavy missions for SpaceX, which includes this reentry technique, and will be posting these up on my YouTube channel starting this week.I look forward to those videos, sounds interesting. 30% reduction in payload is almost exactly what SpaceX quotes too so that lines up well. I think a big issue that me, and it seems others, are having is the return of the second stage. A lot of the issue stems from the fact that SpaceX hasn't really published any concrete plans for this since it is farther down the line in their plans. Whereas the first stage return is not only all planned out, but imminent in about a month like you mentioned. Link to comment Share on other sites More sharing options...
LazarusLuan Posted January 27, 2014 Author Share Posted January 27, 2014 (edited) I look forward to those videos, sounds interesting. 30% reduction in payload is almost exactly what SpaceX quotes too so that lines up well. I think a big issue that me, and it seems others, are having is the return of the second stage. A lot of the issue stems from the fact that SpaceX hasn't really published any concrete plans for this since it is farther down the line in their plans. Whereas the first stage return is not only all planned out, but imminent in about a month like you mentioned.I tend to to believe SpaceX will attempt the same kind of reentry technique for the second stage as well, if for no other reasons than it will be much easier to manage and already carries too much fuel for regular operations when the tanks are topped off. While the retractable engine bell shroud looks really cool on the original video SpaceX published years ago, allowing the shorter landing gear to reach the ground, I believe they will choose the simpler, controlled reentry route for all of the stages that return with the exception of the Dragon itself. Edited January 27, 2014 by LazarusLuan Link to comment Share on other sites More sharing options...
Agathorn Posted January 27, 2014 Share Posted January 27, 2014 Do you guys actually managed to get the first stage into ORBIT, or just suborbital?Keeping extra fuel for this manuever sounds hard because I can BARELY managed to get the first stage into orbit as is, even that is a 50/50 roll of the dice if my flight path was good enough or not.The problem is if you DON'T get it into orbit, then its near impossible to land at KSC.I'd love to see some videos showing flights by everyone. Might be fun to share vids and tips. In fact i'm setting up to do a full space program playthrough using Realism Overhaul, and using ONLY SpaceX launch vehicles for ALL launches. Link to comment Share on other sites More sharing options...
Scootaloo Posted January 27, 2014 Share Posted January 27, 2014 Is this incompatible with FAR for anyone else or just me? It seems after liftoff (I was using Dragon Explorer) that it starts to tumble itself within 3km of the ground. Is something causing some kind of aerodynamic instability that doesn't play nice with Ferram? I notice the same thing with the FASA Atlas Mercury and Agena, as well. Link to comment Share on other sites More sharing options...
Scripto23 Posted January 27, 2014 Share Posted January 27, 2014 (edited) Is this incompatible with FAR for anyone else or just me? It seems after liftoff (I was using Dragon Explorer) that it starts to tumble itself within 3km of the ground. Is something causing some kind of aerodynamic instability that doesn't play nice with Ferram? I notice the same thing with the FASA Atlas Mercury and Agena, as well.Short answer, yes it is incompatible. The nodes on the side of trunk for the solar panel covers, and the nodes on the Dragon capsule don't play nice with FAR. Though you should be able to fly anything that doesn't use the Dragon or trunk without issue. Laz released a patch which will remove those nodes which you can download from the link under "1." in my sig. Or if you're using Real Solar System you can just grab all those links.Agathorn, the first stage should remain suborbital (which is also why it can reenter without a heatshield irl). To land at KSC you need to flip the rocket 180 degrees after separation, you should be at like 120k meters or something, then burn with 3 engines until your horizontal velocity (viewed in mechjeb) is something like 800m/s in the *opposite* direction to which you were initially traveling. This will take you on a ballistic trajectory to within a few kilometers of KSC, exact is too difficult with FAR. Edited January 27, 2014 by Scripto23 Link to comment Share on other sites More sharing options...
Agathorn Posted January 27, 2014 Share Posted January 27, 2014 Short answer, yes it is incompatible. The nodes on the side of trunk for the solar panel covers, and the nodes on the Dragon capsule don't play nice with FAR. Though you should be able to fly anything that doesn't use the Dragon or trunk without issue. Laz released a patch which will remove those nodes which you can download from the link under "1." in my sig. Or if you're using Real Solar System you can just grab all those links.Agathorn, the first stage should remain suborbital (which is also why it can reenter without a heatshield irl). To land at KSC you need to flip the rocket 180 degrees after separation, you should be at like 120k meters or something, then burn with 3 engines until your horizontal velocity (viewed in mechjeb) is something like 800m/s in the *opposite* direction to which you were initially traveling. This will take you on a ballistic trajectory to within a few kilometers of KSC, exact is too difficult with FAR.But then I can't use MechJeb to control the landing anymore Link to comment Share on other sites More sharing options...
Scripto23 Posted January 27, 2014 Share Posted January 27, 2014 But then I can't use MechJeb to control the landing anymore Well not quite, you can still use it . What I do is what I mentioned above and then once have my ballistic trajectory set then you can use mechjeb for the final landing portion. Though it's best to only activate it once you're below like 400m/s otherwise it will try and slow you down by firing the engine because it will see suicide burn countdown drop into the negatives. But his actually isn't necessary with FAR because aerobraking will slow you down considerably near sea level and you'll see you're suicide burn countdown go back into the positives. Just a way to save gas. I should make a video... Link to comment Share on other sites More sharing options...
Agathorn Posted January 27, 2014 Share Posted January 27, 2014 Well not quite, you can still use it . What I do is what I mentioned above and then once have my ballistic trajectory set then you can use mechjeb for the final landing portion. Though it's best to only activate it once you're below like 400m/s otherwise it will try and slow you down by firing the engine because it will see suicide burn countdown drop into the negatives. But his actually isn't necessary with FAR because aerobraking will slow you down considerably near sea level and you'll see you're suicide burn countdown go back into the positives. Just a way to save gas. I should make a video...Thanks for the tips.Yeah like I said I think we should all share videos! The real SpaceX has really inspired me. Link to comment Share on other sites More sharing options...
LazarusLuan Posted January 27, 2014 Author Share Posted January 27, 2014 Short answer, yes it is incompatible. The nodes on the side of trunk for the solar panel covers, and the nodes on the Dragon capsule don't play nice with FAR. Though you should be able to fly anything that doesn't use the Dragon or trunk without issue. Laz released a patch which will remove those nodes which you can download from the link under "1." in my sig. Or if you're using Real Solar System you can just grab all those links.Agathorn, the first stage should remain suborbital (which is also why it can reenter without a heatshield irl). To land at KSC you need to flip the rocket 180 degrees after separation, you should be at like 120k meters or something, then burn with 3 engines until your horizontal velocity (viewed in mechjeb) is something like 800m/s in the *opposite* direction to which you were initially traveling. This will take you on a ballistic trajectory to within a few kilometers of KSC, exact is too difficult with FAR.I've removed all the node attachment points for the Dragon 2 capsule and the trunk in the update I posted in this forum on Friday, so that shouldn't be an issue any longer. Do I need to update the full mod pack first? Link to comment Share on other sites More sharing options...
Roxette Posted January 27, 2014 Share Posted January 27, 2014 1. Overwrite the LazTek folder to add these part updatesThat link might not be what you think it is Link to comment Share on other sites More sharing options...
Scripto23 Posted January 27, 2014 Share Posted January 27, 2014 (edited) I've removed all the node attachment points for the Dragon 2 capsule and the trunk in the update I posted in this forum on Friday, so that shouldn't be an issue any longer. Do I need to update the full mod pack first?Yeah that update worked great, thanks for that. What do you mean by update the full mod pack first?That link might not be what you think it is Ah it appears that link does not work. You can find the download in Laz's post #406 page 41 of this thread until I fix that link. Edited January 27, 2014 by Scripto23 Link to comment Share on other sites More sharing options...
Agathorn Posted January 27, 2014 Share Posted January 27, 2014 Scripto are you aware your sample .craft files are using non SpaceX and no-stock parts? I wanted to open up your examples to see how you were providing fuel to your RCS (and how you were using RCS in general) but they seem to be using parts I don't have Link to comment Share on other sites More sharing options...
Scripto23 Posted January 27, 2014 Share Posted January 27, 2014 (edited) Ah sorry, that's probably the B9 RCS thrusters. I'm using them because they provide 5-way thrust instead of stock which is 4-way and also are aerodynamic. I can replace them with stock and upload that craft.Edit: Not sure why my tanks won't hold RCS fuel all of a sudden... Edited January 27, 2014 by Scripto23 Link to comment Share on other sites More sharing options...
Agathorn Posted January 27, 2014 Share Posted January 27, 2014 That's probably it. I don't have B9 since I don't care about spaceplanes Link to comment Share on other sites More sharing options...
Agathorn Posted January 28, 2014 Share Posted January 28, 2014 Edit: Not sure why my tanks won't hold RCS fuel all of a sudden...Yeah like I said I was wondering how you were handling RCS, and fuel for it. Between RO's restrictions on fuel flow, and the limited tanks to carry hydrazine, I found myself having to put a small stretchy tank on each stage to carry fuel for the RCS on that stage. It annoyed me.I wonder where SpaceX really stores the RCS fuel for each stage? Link to comment Share on other sites More sharing options...
Scripto23 Posted January 28, 2014 Share Posted January 28, 2014 Yeah like I said I was wondering how you were handling RCS, and fuel for it. Between RO's restrictions on fuel flow, and the limited tanks to carry hydrazine, I found myself having to put a small stretchy tank on each stage to carry fuel for the RCS on that stage. It annoyed me.I wonder where SpaceX really stores the RCS fuel for each stage?Thing is those tanks were holding RCS, but maybe a recent update changed that? SpaceX uses MMH + N2O4 for the Draco thrusters as RCS on the Dragon and upperstage, and then cold nitrogen thrusters as RCS for the first stage. RF doesn't currently have the option for Nitrogen RCS so I was just using monopropellant. I think RF should allow the tanks to hold RCS fuel though because you can just think of it as a smaller tank/bladder held inside the skin of the main tank. They wouldn't just slap an external tank on the outside. Currently the tank type is set to Default, what tank types can hold RCS? Link to comment Share on other sites More sharing options...
Agathorn Posted January 28, 2014 Share Posted January 28, 2014 He changed this in the last update:*Non-SM, Non-RCS tanks can no longer hold monopropellant. Link to comment Share on other sites More sharing options...
Guest Posted January 28, 2014 Share Posted January 28, 2014 RF doesn't currently have the option for Nitrogen RCS so I was just using monopropellant.The latest version of RF features Nitrogen specifically for cold gas thrusters. I used this on FASA Agena. Link to comment Share on other sites More sharing options...
Scripto23 Posted January 28, 2014 Share Posted January 28, 2014 The latest version of RF features Nitrogen specifically for cold gas thrusters. I used this on FASA Agena. Oh, good to know. I'm going to integrate that into the SpaceX rockets then. Link to comment Share on other sites More sharing options...
Recommended Posts