Reinhart Mk.1

If I ever make it back from Eve

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1 hour ago, FleshJeb said:

The Spikes have superior ISP to the vector/twin boar for the vast majority of the atmo profile. Right now it's a drag problem, not a thrust problem. I've got so much lift, I actually have to throttle back the three Spikes to fly surface prograde without pitching up too much.

Where is your CoL relative to your CoM on that thing? It seems like you must be pretty tail-heavy, especially when empty.

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im so glad to see everyone sharing their designs, they all look really nice :)

my current lander actually can breach the atmosphere going so fast it actually explodes when do the gravity burn... i mean that's definite progress based on my last one. damn you really have to LEARN to do everything all over again on eve...

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8 minutes ago, Reinhart Mk.1 said:

im so glad to see everyone sharing their designs, they all look really nice :)

my current lander actually can breach the atmosphere going so fast it actually explodes when do the gravity burn...

On Eve, exploding in the upper atmosphere is a definite sign of progress!

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3 minutes ago, herbal space program said:

On Eve, exploding in the upper atmosphere is a definite sign of progress!

I KNEW IT, just gotta control it i guess and make sure im not going too slow? Like just below the point of exploding seems like i'd start to project a nice orbit

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8 minutes ago, Reinhart Mk.1 said:

I KNEW IT, just gotta control it i guess and make sure im not going too slow? Like just below the point of exploding seems like i'd start to project a nice orbit

Too slow? Generally when you blow up on ascent, it's because you've pitched down too much, too soon and you're consequently going too fast for too long at too low an altitude.  Is that not what happened in your case?

Edited by herbal space program

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2 minutes ago, herbal space program said:

Too slow?

no i mean like... slow enough to where i dont explode but fast enough to where im not wasting fuel/delta v? the whole slowing down at a certain part of the atmosphere/terminal velocity is really confusing me lol

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1 hour ago, herbal space program said:

Where is your CoL relative to your CoM on that thing? It seems like you must be pretty tail-heavy, especially when empty.

The pitch-up is a side effect of having the CoLift slightly in front of the CoM, but when added to the CoDrag, the net effect is behind the CoM. I usually build space planes to be able to fly hands-off to orbit on Surface Prograde, and I forgot I could trim...DUH.

I think this will probably answer your questions better than more text (Neither KER nor RCS BA is set up right, but I'm just using the CoM indicator):

nhATrNP.png

Edited by FleshJeb
Noticed some stuff about pic.

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37 minutes ago, Reinhart Mk.1 said:

no i mean like... slow enough to where i dont explode but fast enough to where im not wasting fuel/delta v? the whole slowing down at a certain part of the atmosphere/terminal velocity is really confusing me lol

Yes, that's about the size of it. If you're trying to push the dV envelope, taking the lowest trajectory to orbit you can without exploding is basically what you're doing.  For you, it would probably better to aim significantly higher than that, since as long as you have plenty of dV your margin of error is much bigger that way. May I ask what is the total vacuum dV of your craft and the Eve vacuum TWR of each of its stages? If you have MJ, it should be really easy to see it on the "dv stats" display. I totally understand if you'd rather keep your cards hidden, but with that info it should be pretty easy to determine where you stand...

26 minutes ago, FleshJeb said:

The pitch-up is a side effect of having the CoLift slightly in front of the CoM, but when added to the CoDrag, the net effect is behind the CoM. I usually build space planes to be able to fly hands-off to orbit on Surface Prograde, and I forgot I could trim...DUH.

I think this will probably answer your questions better than more text:

nhATrNP.png

Yeah, that's a sight better than it looked to me by eyeball. I also see you have all sorts of high-leverage front-end ballast under that fairing, which along with the wet wings in the back must make things easier as you use up fuel. That could become more of a problem if you have to lose a bunch of wing area, but the capacity of all those seems like a fair bit more than you actually need. I guess I don't usually build planes that stick out so far in the front, so I generally can't counterbalance them so effectively with the payload part. I should keep that in mind more in my future designs...

Edited by herbal space program

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20 minutes ago, herbal space program said:

total vacuum dV

wow im surprised i didn't think of this, im not sure atm. right now been just been in-game trying to orbit lol

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1 minute ago, Reinhart Mk.1 said:

wow im surprised i didn't think of this, im not sure atm. right now been just been in-game trying to orbit lol

If you have a MJ pod on board, it will tell you those things at any time during your mission. Just using the stock dV interface to see what the surface dV is when you're on the ground would also be helpful though. To see vacuum dV in Stock, I think you need to be in the VAB/SPH.

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1 minute ago, herbal space program said:

If you have a MJ pod on board, it will tell you those things at any time during your mission. Just using the stock dV interface to see what the surface dV is when you're on the ground would also be helpful though. To see vacuum dV in Stock, I think you need to be in the VAB/SPH.

hmmm i have kerbal engineer (had to get it for eve) but for the most part i try not to download too many mods, if it's realistic and plausible then i would though! MJ sounds like it doesn't kill immersion

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41 minutes ago, Reinhart Mk.1 said:

hmmm i have kerbal engineer (had to get it for eve) but for the most part i try not to download too many mods, if it's realistic and plausible then i would though! MJ sounds like it doesn't kill immersion

If you have the latest stock version, you could also just go to the VAB and load your ship. If you select "Eve" and "vacuum" on the dV tab there, it will give the vacuum dV and Eve TWR of each stage if you open the tab on the right-hand staging bar. It also says the total dV at the bottom. Those are important numbers if you're trying to do this.

 

Edit: ...And to save time, I'll just say that for your first lifter, around 7 km/s of vacuum dV with those engines would probably be a comfortable target, provided that your first stage has an in-situ TWR of at least 1.1 at launch, and none of the others early in your ascent spend much time below a value of 1.  You should just note where you're taking off/staging and use the Eve altitude slider in the stock VAB dV tool to estimate your TWR. If you keep it above 1 up to an altitude of at least 25 km, you can afford to let it get well below there on the later parts of your ascent, so long as you establish a climb rate of at least ~450 m/s at that altitude, based on my many recent trials. But that's the low end of the envelope. With 7 km/s of vacuum dV (using those engines), you can basically boost to a 70 km AP at 45 degrees from 20km on, coast to a little more than a minute short of there, then boost prograde as hard as you can, with just enough TWR to keep your AP out ahead of you as you speed up, until your AP up to around 95 km. Then  coast until around 20s before you hit it, and then  boost towards your prograde horizon line until you are in orbit. For that part just make sure your final stage has a  Kerbin TWR of at least 0.7 or so, or you might find it difficult to circularize quickly enough.That is definitely not the most efficient way to get to Eve orbit, but it's pretty robust, and I have a feeling that if you have one success you'll be able to build on it pretty quickly.

Edited by herbal space program

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So I have a new video, definitely the most successful design but I still seem to fall short. In all honesty it's probably my ascent but HEY... i'm proud

(also quality might be 360p for a minute or two, should be normal in a minute or two)

 

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I saw a "Little" mistake, for a stable turn, use low throttle to turn into desired angle, then max throttle around desired angle, for final maneuver, execute it in around "time before node" to be safe, the ignition have to be immediate, if execution time > time before node.

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1 minute ago, GRS said:

I saw a "Little" mistake, for a stable turn, use low throttle to turn into desired angle, then max throttle around desired angle, for final maneuver, execute it in around "time before node" to be safe, the ignition have to be immediate, if execution time > time before node.

this honestly might be the most vital piece of advice at this point, damn i just rewatched the video of my first lander. that thing was a mess :blush:

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29 minutes ago, Reinhart Mk.1 said:

So I have a new video, definitely the most successful design but I still seem to fall short. In all honesty it's probably my ascent but HEY... i'm proud

(also quality might be 360p for a minute or two, should be normal in a minute or two)

 

After watching that, I think I can say that You Will Go To Space Today if you do just 2 things: 

1) Start going sideways sooner! You should be pitched at  45 degrees or more by the time you hit 25 km, or else you are gonna get killed by gravity losses. Your initial stages are doing a great job of lobbing you skywards, but the whole point is to boost upwards as little as possible to allow you to go sideways at 3.2 km/s, so you need to turn that sideways as early as you can. Start your gravity turn at 5000 m, and get it to 45 degrees by 25 km.  Less sideways than that, and you're just sacrificing dV to the gravity gods.

2) That whole stage where you have just the core Vector burning is killing you! Your TWR is insufficient, and you're just losing speed while boosting straight up, giving every bit of momentum you had up to gravity. The good news is that all you need to do to fix it is to fire up those aerospikes on the stage above at the same time you stage off your second pair of side boosters. Between that and being way more sideways when that's happening, you should be all good!

Edited by herbal space program

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No problem in staying on Eve, with its beautiful sunrises/sets and pristine rocket fuel lakes!

If you really want to leave, Send down grabber ships with a lot of high TWR engines on the tug, then pull it to orbit and send a refueling mission.

Or if you want to keep the ship as a landmark, send the ship from option one, (sans grabber)  and get the Kerbal, rocket off and do the rest of the other option.

 

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2 minutes ago, herbal space program said:

After watching that, I think I can say that You Will Go To Space Today if you do just 2 things: 

1) Start going sideways sooner! You should be pitched at  45 degrees or more by the time you hit 25 km, or else you are gonna get killed by gravity losses. Your initial stages are doing a great job of lobbing you skywards, but the whole point is to boost upwards as little as possible to allow you to go sideways at 3.2 km/s, so you need to turn that sideways as early as you can. Start your gravity turn at 5000 m, and get it to 45 degrees by 25 km.  Less sideways than that, and you're just sacrificing dV to the gravity gods.

2) That whole stage where you have just the core Vector burning is killing you! Your TWR is insufficient, and you're just losing speed, giving every bit of momentum you had up to gravity. The good news is that all you need to do to fix it is to fire up those aerospikes on the stage above at the same time you stage off your second pair of side boosters. Between that and being way more sideways when that's happening, you should be all good!

I love this community so much i swear, i tried a few different variations on my last design and this one but i actually haven't tried that yet tbh. BUT on my last design doing that always made the lower tanks collide with the ship ;.;

8 minutes ago, herbal space program said:

fire up those aerospikes on the stage above at the same time you stage off your second pair of side boosters.

yoooo this might fix it colliding with the ship  T H A N K  Y O U

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3 minutes ago, Reinhart Mk.1 said:

I love this community so much i swear, i tried a few different variations on my last design and this one but i actually haven't tried that yet tbh. BUT on my last design doing that always made the lower tanks collide with the ship ;.;

Two pointers there: 

1) Place the decoupler as high on the side stack as you can and then place a single strut as low as you can. The lower strut will act as a fulcrum, making the tank stage off as far away as possible.

2) Make sure you are pointed dead to prograde when you stage it off. Any other angle and those fierce aerodynamic forces will slam it into your core stage.

Edited by herbal space program

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16 minutes ago, herbal space program said:

Two pointers there: 

1) Place the decoupler as high on the side stack as you can and then place a single strut as low as you can. The lower strut will act as a fulcrum, making the tank stage off as far away as possible.

2) Make sure you are pointed dead to prograde when you stage it off. Any other angle and those fierce aerodynamic forces will slam it into your core stage.

you are truly appreciated, i wish they had a kerbal salute emoji

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7 hours ago, herbal space program said:

1) Place the decoupler as high on the side stack as you can and then place a single strut as low as you can. The lower strut will act as a fulcrum, making the tank stage off as far away as possible.

I'm going to have to disagree.

#1- Struts are relatively heavy and draggy

#2- They don't act as a fulcrum, rather the high decoupler just pushes the top away. Any "fulcrum" effect that you see is an illusion due to momentum. The way the game works, that strut disappears instantly when the de-coupler fires. You can place the decoupler high, and then use autostrutting for the same effect, but less mass and drag.

What I've done for Kerbin launches is to have fins just slightly ahead of the CoM of the stage that gets discarded (which should be behind the CoM of the stage when its fueled), and at a slight (<5 degree AoA) angle so that aerodynamic forces pull the spent stages away... that or a combination with sepratrons.

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9 hours ago, herbal space program said:

After watching that, I think I can say that You Will Go To Space Today if you do just 2 things: 

 

I thought the same thing.  But I noticed different things. 

1.Turn off gimbal for the side vectors.  They are probably wasting over a hundred dV by gimballing and the center one has plenty of gimbal.  

2. Always stay pointed at the blue part of the nav ball above the horizon.  I noticed the maneuver vector and prograde vector were in the brown zone below the horizon.  That means you were lowering your own apoapsis.  I would never point below the horizon going for orbit.  Exactly 0 degrees pitch straight horizontal is fine.  But somewhere between the horizon and the the instantaneous prograde vector is usually best.  I usually watch my time to apoapsis.  If time to apoapsis is increasing I pitch toward the horizon and then lower throttle.  If time to apoapsis is decreasing then I raise the nose up toward the instantaneous prograde vector.  

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13 hours ago, KerikBalm said:

I'm going to have to disagree.

#1- Struts are relatively heavy and draggy

#2- They don't act as a fulcrum, rather the high decoupler just pushes the top away. Any "fulcrum" effect that you see is an illusion due to momentum. The way the game works, that strut disappears instantly when the de-coupler fires. You can place the decoupler high, and then use autostrutting for the same effect, but less mass and drag.

What I've done for Kerbin launches is to have fins just slightly ahead of the CoM of the stage that gets discarded (which should be behind the CoM of the stage when its fueled), and at a slight (<5 degree AoA) angle so that aerodynamic forces pull the spent stages away... that or a combination with sepratrons.

1) Struts are not too heavy and draggy for what OP is trying to do. OP has plenty of ship to get to orbit, struts or not, so you are making the perfect the enemy of the good here.

2) Maybe the fulcrum effect is an illusion, but I was told to do it that way (before there was autostrut, to be fair) on this forum, by somebody with 5 dots below their handle, and I know that it works well every time when I do it that way and often not when I don't. Maybe it's all in their and/or my mind and/or the code has changed since then, but it sure looks to me like that tank pivots on the strut attachment point as it detaches. You can say the strut disappears "instantly", but there is no instantly in a computer simulation. Do you know for a fact that the code makes the strut go away before the decoupler applies any force to the tank?  If there was a forum discussion about this where it was resolved, then perhaps you can point me to it.  Otherwise I will put together a quick experiment later and see. 

2) You certainly don't disagree about placing the decoupler well above the COM of the side stack, do you? Let's not throw that baby out with the bathwater. On a highly dynamic rocket ascent like this, not doing that is deadly.

Edited by herbal space program

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18 hours ago, Reinhart Mk.1 said:

So I have a new video, definitely the most successful design but I still seem to fall short.

This reminds me of the old days, when we had to claw our way out of the soup.... and going too fast was just as bad as being too slow.

You've already been told to start a turn much earlier. I'd like to add that you're staging too often and too early. If you still have the savegame, just turn on crossfeed on the decouplers and treat the whole 5-vector assembly as a single stage. I have an inkling that this will perform better than what you're doing right now.

(You can then proceed to building a rocket that has five decouplers on a single, more streamlined stack -- the quicksave-and-cossfeed approach is merely a way of getting a quick preview of what you can expect.)

 

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