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Shaking off the rust, trying to get into orbit


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So let me start by saying that I haven't played KSP in over two years.  Everything I might have known once has either been forgotten (by me) or changed (by the devs).  So with that level of ingorance in mind, let's roll:

 

I'm trying to get into LKO.  A very simple problem.  I've consulted dV maps (at least, the most recent one I could find).  I've used KER to assist in building my craft.  I've put together what I thought was a pretty decent composition.

After much struggle, I finally managed to barely get the upper stage of this thing into orbit.  As in, I hit a periapsis of 70km with less than 9 units of fuel left.

 

I honestly don't know what I'm doing wrong.  I don't know if it's a design issue, but nothing screams at me as the guilty culprit.  I don't know if it's a "My launch and ascent trajectories are garbage" issue, becaue I don't know what the optimal ascents even are at this point and haven't been able to find much information out there that's more recent than version 0.20-something.  All I know is that even with over 4,100 dV, I can only achieve orbit by the absolute slimmest of margins, and irregularly at that.

 

If anyone has any advice on this specific design, ascent trajectories / gravity turns in general, or anything else that would help me go to space consistently, I would be very appreciative.

 

(As far as mods go, I'm using a lot of mods, but FAR isn't one of them, so I believe the aerodynamics should be "stock.")

 

P.S. If you're wondering why my top-most propulsion stage has four Delta-Deluxe Winglets on it, it's because that stage, like seemingly all of my craft, has a tendency to try to flip to the left (where "left" is the side of them that is closest to the VAB when sitting on the launch pad).  I have no idea why this happens.  I added the winglets in an effort to provide a small amount of drag and control surface steering in the upper atmosphere.  It was somewhat successful.

 

Edit:  After multiple attempts with both my original (posted) craft, and with a different experimental craft in Sandbox mode, I'm still finding that it takes me on average around 4,200m/s dV in order to achieve a roughly-80km orbit.  This seems to happen regardless of how I tweak my launch profile or rocket design—either I'm spending 4,200m/s in order to get into orbit, or I'm not getting into orbit.

Edited by Landwalker
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First off, if your engines have gimbals, the fins are completely superfluous.  I see you 're using a Reliant in the first stage, so you'll probably want some fins, as far back as possible, on that stage, but by the time the upper is on its own, the reaction wheel in your probe core ought to be sufficient.  Additionally, you probably don't need fins that big or with control surfaces on them.  If the Pug is based on the Terrier, it ought to have some gimbal, and the fins on the upper stage are counterproductive.  A tendency to yaw to the left may be due to assymetry, either in mass distribution or external mounting (the radial parachutes produce significant side force if single mounted on a stage).

If you're not getting to orbit with a vessel that has 10% or so delta-V margin, it's probably your launch profile.  As I understand it, aero losses are significantly lower in 1.2.2 and 1.3 than in older versions post 1.0, so initiating gravity turn earlier than you remember may improve things.  I've recently launched a couple vessels (my Explorer II and Explorer IIp -- see my "What Did You Do" posts from a week or so ago) with barely enough dV to orbit, and I found (with a 1.8 to 2.0 TWR) that it wasn't too early to start the gravity turn with a 5 or 10 degree tilt as early as 30 m/s (though that was with a vessel that had no gimbals in the booster and non-steerable fins, so it was locked hard on prograde as soon as it was moving well).  With only the Mk. 1 command pod's reaction wheel, I found it worked very well to initiate maximum yaw eastward immediately on ignition, and hold that command all the way to MECO, or until the air thinned enough that the fins lost effectiveness.

If you're getting an apoapsis higher 80 km before you circularize, you're probably turning over too late for a vessel with minimal dV.

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You rocket is a bit too powerfull, what can make difficult to follow a proper gravity turn. Even then It shouldn't take 4100m/s to orbit. The problem is your ascent profile.

Performing a gravity turn is in fact very simple, give the rock a small initial tilt and let it fly itself to orbit. The trick pat is to get that small tilt rigth, a degree can make the whole difference.

So just experiment a bit to give more or less of a initial tilt until you find what is the ideal for each rocket. some rules of thumbs:

-more powerfull rockets should be more agressive steered to start the gravity turn.

-your rocket shuould be pointing very close to prograde (less than 5°) most of the time.

-if your time to apoapsis is screasing slowly that is a good signal.

-if you reach 10km with about 45° of inclination is a good signal.

 

Lastly my offer of a craft that can do a gravity turn by itself, it is pre-tilted in the editor so you just need to press space to launch and stage. Its TWR is a bit high, mind you, but good to give you a idea of the kind of trajectory will put you in orbit reliabily.

 

 

 

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Thanks for the feedback.  I suspect the radial parachutes are the culprits for the aggressive yawing—I was indeed single-mounting them (I didn't think they were significant enough to throw off an entire craft). 

 

I managed to get this thing into a roughly 80km orbit while consuming 3800m/s dV, which is by far my best result.  Unfortunately, I don't really know in detail what I did differently. 

 

The Pug engine has significantly lower thrust (25 kN in a vacuum) compared to a Terrier (60 kN), slightly worse vacuum Isp (330 vs. 345), but significantly better atmospheric Isp (150 ASL vs. 85 ASL).  It does not have gimbal capabilities.  The Terrier is almost certainly the better choice for this craft, but I hadn't unlocked it yet in that career save.

 

I tried rebuilding a variation on my initial "problem rocket" with some changes:  No fins on the upper stage, no SRBs, no radial parachutes, and I slightly redistributed the fuel to put more in the lifter stage and less in the upper stage.  I tried replacing the fins with non-controlling winglets, but the rocket handled worse than a barge until around 10km, at which point it completely lost all control.  The reaction wheels in the OKTO probe core and the small inline reaction wheel part just couldn't exert any influence over the rocket.  This one weighed in just shy of 4,300m/s vacuum dV

It handled pretty well for the first stage (at least, I thought so).  I put on about a 7-8º angle pretty early on, rode that to around 200m/s (around 3.6km), and then locked prograde on the SAS.  I tried to keep my TWR under 2.00 for the whole duration.  I ended up with an angle of around 45º anywhere from 16km to 20km, and at first stage burnout, I was between 25º around 23km and 35º around 27km.  But the second stage basically came cartwheeling out of the decoupler with nothing to stabilize it—the same problem I ran into originally—and ruined the whole launch.  This occurred multiple times, so I have no doubt that there's a fundamental flaw in the second stage.  I don't know why it exits the decoupler so... badly.  It seems to do this regardless of whether it "comes out firing" or whether I decouple with no throttle at all.  Given that the second stage is a failure (and given that I don't know how to fix it), I can't evaluate my launch profiles any further than that.

Edited by Landwalker
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@Landwalker I noticed that you don't have the "Atmospheric" button checked in the KER stage delta-v readout. In the newer versions of KSP the ISP or engine efficiency of the engines is different in atmosphere versus the vacuum of space. That Pug engine is designed for vacuum operation and won't be very efficient in atmosphere so it could have a very low thrust-to-weight ratio if you are still deep in the atmosphere when it activates. This will also have the effect of reducing your total available delta-v. It should be fine if you can get it above about 30 km before activating it where the atmosphere is thinner.

As for doing a good gravity turn: you should no longer go straight up before turning at 10km like in the olden days. Now the best gravity turn is to burn upwards until you have at least 100-200m/s speed (about 1km up for most rockets) then gradually start to tip your rocket eastwards very very slowly. Follow a gradual curve so that you pass through 45 degrees at around 10km up and continue softly nudging it over little by little until you are horizontal by the time you reach 60 kilometers. A well balanced rocket should even be able to "fall" over in a graceful arc from launch to apoapsis with only a slight nudge eastwards after liftoff. A decent TWR is key for achieving this. A thrust-to-weight ratio of about 1.4 at launch is usually a good place to start.

Edit: you posted your last reply as I was composing the above.

Again, make sure you select the "Atmospheric" button in the KER readout to see the delta-v of your engines when operating in atmo. Also, 45 degrees at 16-20km isn't aggressive enough. You should be at 45 at about 10km. You can help achieve this by reducing your thrust at times. Lower thrust to flatten out, higher thrust to gain altitude.

Edited by HvP
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Yeah, after more attempts (and more failures), I've realized a few things:

  • Piloting Issues
  1. I didn't / don't know what the preferred launch profile is, so I have been going at it too steeply. 
  2. I am not good at actual piloting, especially as far as "subtle" maneuvers are concerned.  Whenever I try to make flight adjustments, I seem to either have no effect whatsoever (less common), or cause erratic, herky-jerky behavior in the craft.  I had a shower thought that perhaps this is a result of me not disabling stability assist during maneuvers, causing the craft the careen back and forth in a tug-of-war between my all-or-nothing inputs and the desired bearing of the stability assist.  I'll have to put this to the test and see if there are any improvements to be made.
  • Craft Design
    1. As @HvPpointed out, the Pug rocket has poor atmospheric performance.  I had actually thought about the Atmospheric/Vacuum differences and, believe it or not, had considered them, but the dV chart I rely on specifically stated that given values were "vacuum dV".  My rocket had 4,100+ m/s of vacuum dV, so I felt like I was good to go.  However, the Terrier's atmospheric performance is even worse, so I'm not sure what to do here.
    2. In order for the Pug (or Terrier) to be viable in the position I have them in, they need to be able to engage at high altitudes or space.  The nature of my designs has tended to result in the first stage burning out no higher than 26-27km (and that was on my too-steep profiles).  I'm probably losing a lot of efficiency from the Pug because it's being required to operate in the atmosphere too early.  This is probably also why in my previous attempts at a shallower launch profile, I couldn't even get out of the atmosphere at all.  Perhaps I should consider a heavier, more versatile rocket in the Stage 2 role, like the LV-T45 Swivel.  Alternatively, perhaps it would make sense to redistribute more towards the first stage—the problem is that I feel like the gains to be had there are marginal.
    3. For some reason my crafts seem to be... not very cooperative.  Some of this is obviously on me (see Piloting Issues #2).  Some of it is probably also on me, except that I don't know exactly what it is.  This includes things like my upper stage cartwheeling out of control, for example.  Unless I know why things happen, I can't fix them.  :/

I'll try to incorporate some of the new knowledge (particularly about launch profiles) in my next tests tomorrow night and see how much (if any) improvement I'm able to see.

Edited by Landwalker
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1 hour ago, HvP said:

Now the best gravity turn is to burn upwards until you have at least 100-200m/s speed (about 1km up for most rockets)

Well, not for rockets with TWR around 3, for those you want a more agrassive gravity turn. From my experience 5°+ right from the launchpad will do the trick for those.

 

1 hour ago, Landwalker said:

 I tried to keep my TWR under 2.00 for the whole duration.

Don't do it. Using a less powerful but lighter engine  can be beneficial because the increased deltaV budget, but throttling down just cause the gravity losses to increase*. As long as you can get the initial 'nudge' correct there is mostly** no reason to throttle down.

10 minutes ago, Landwalker said:

flight adjustments

It is a bit harsh, but flight adjustment are only necessary if you did something wrong earlier. Either the initial 'nudge' or something in the design.

Designs with lower TWR(1.3 - 1.7) tend to be more forgiving since you have a longer time to orbit and will be at lower velocity at the time of the corrections. In any case those deviations cause cosine loses (thrust-velocity  misalignment) and increase drag losses (larger area exposed to airstream) so you should try to avoid the need for those correction in the first place.

For the 'nudge' practice, practice, practice. Or designs with pre-tilt in the editor.

 

*If you have a readout of Max-Q and can keep your rocket at that speed ok, that is where [gravity losses] + [drag losses] are minimal. Otherwise focus on minimizing gravity losses , what you do by getting to orbital velocity ASAP. As long you are not overheating drag will be the  lesser of those two issues.

**too much drag can melt your craft. Also the above mentioned Max-Q.

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Helping your vessel get to orbit is a matter of reducing drag and weight. You are using a 2.5m central stack. That has a lot more drag than a 1.25m stack. So you can make the ship a little taller and slimmer.

Looks like you have a heatshield or two in there somewhere from the KER readout. Those are extremely heavy, and are completely worthless for reentering from LKO. Try turning the force on your second stage decoupler down to something near zero. Clearly the decoupler is doing something very bad to your craft, or there is some clipping going on in that second stage.

 

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1 hour ago, Landwalker said:

In order for the Pug (or Terrier) to be viable in the position I have them in, they need to be able to engage at high altitudes or space.  The nature of my designs has tended to result in the first stage burning out no higher than 26-27km (and that was on my too-steep profiles).  I'm probably losing a lot of efficiency from the Pug because it's being required to operate in the atmosphere too early. 

I don't know anything about the Pug, but for the Terrier (and other stock "vacuum engines" like the Poodle and nuke) that's PLENTY of altitude.  By 10km altitude the Terrier has an ISP of about 300, which means it's already better than most of the atmospheric launch engines.  By 20km, these engines are within a rounding error of their vacuum ISP.  

2 hours ago, Landwalker said:

I managed to get this thing into a roughly 80km orbit while consuming 3800m/s dV, which is by far my best result.  Unfortunately, I don't really know in detail what I did differently. 

Looking pretty good.  Simpler is usually better, and you're definitely moving that direction.  If you want to add more range to this rocket, I think the place to start is just to add more fuel to the first stage.  The Reliant is a pretty powerful engine for its size, and your rocket has plenty of extra TWR to accommodate some more fuel.  

More generally, it's probably not the biggest issue, but those fins are adding a lot of mass, drag and (if you're playing career mode) cost.  Admittedly, there's a pretty big gap in the payload spectrum where the Swivel is not big enough, and something like the Skipper is too big.  It might be possible to find another arrangement that gives you the needed attitude control with a little more efficiency.  A few ideas (with the caveat that I'm not sure of your tech tree level or mods):

  • Central Svivel with a couple SRBs for extra launch thrust
  • Central Reliant with a couple Spiders or Twitches on the side (this is surprisingly effective, and quite a bit cheaper than fins)
  • A couple of Thuds, with either nothing under the middle or something like the Spark.
  • Just use the Swivel on smaller rockets - this might be viable for your revised rocket.  Its sea level thrust and ISP are pretty bad, but if you can put up with that for a few seconds, it gets up into the tolerable range fairly quickly.
  • Try smaller/cheaper fins, like the smallest elevons.  With a stable rocket it should not take much control authority to keep it on track.  
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9 hours ago, Landwalker said:

I ended up with an angle of around 45º anywhere from 16km to 20km, and at first stage burnout, I was between 25º around 23km and 35º around 27km. 

That is still a very steep trajectory, wich is only needed for very low TWR rockets.

9 hours ago, Landwalker said:

But the second stage basically came cartwheeling out of the decoupler with nothing to stabilize it

Sound like a clipping problem. Maybe the mods you're using have issues with the colliders.

 

I don't know what you're doing wrong in terms of delta v. My rockets need (dependent on their TWR) between 3500 and 3100 m/s of vacuum delta v to get to LKO.

3800 doesn't sound too bad, you just have to optimize your ascent a bit. For most rockets, it's best to go as shallow as possible.

Edited by Physics Student
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8 hours ago, Spricigo said:

It is a bit harsh, but flight adjustment are only necessary if you did something wrong earlier. Either the initial 'nudge' or something in the design.

Well, as-stated, I clearly am doing something wrong.  Knowing that I'm doing something wrong, however, without knowing what that something is, is not as helpful as people seem to think it is.

 

8 hours ago, bewing said:

Helping your vessel get to orbit is a matter of reducing drag and weight. You are using a 2.5m central stack. That has a lot more drag than a 1.25m stack. So you can make the ship a little taller and slimmer.

Looks like you have a heatshield or two in there somewhere from the KER readout. Those are extremely heavy, and are completely worthless for reentering from LKO. Try turning the force on your second stage decoupler down to something near zero. Clearly the decoupler is doing something very bad to your craft, or there is some clipping going on in that second stage

You're half-right.  All of my builds so far have been 1.25m stacks.  The failed Circe is no exception.

I do have a heat-shield, though.  It's in between the black-and-white circle of service bays just under the probe core and the top-most decoupler.  Worthless for reentering from LKO it may be, but removing it will just increase my total dV.  And since I already have 4,100m/s dV, "give myself even more dV that I can waste" doesn't seem like the solution.

I'll try reducing the force of the decoupler between Stage 1 and Stage 2 (which in the original picture is right below the marked Pug engine).  I considered doing that last night, but ran out of time.

7 hours ago, Aegolius13 said:

I don't know anything about the Pug, but for the Terrier (and other stock "vacuum engines" like the Poodle and nuke) that's PLENTY of altitude.  By 10km altitude the Terrier has an ISP of about 300, which means it's already better than most of the atmospheric launch engines.  By 20km, these engines are within a rounding error of their vacuum ISP

Good to know about the ISP and altitude.  Thanks for that info.

I figured some people wouldn't know about the Pug, which was why I made sure its stats window was in the picture.  It has significantly better ASL ISP than the Terrier, but slightly worse Vac ISP and less than half of the thrust.  The relevant points here, I suspect, are "slightly worse Vac ISP" and "less than half the thrust." 

Quote

More generally, it's probably not the biggest issue, but those fins are adding a lot of mass, drag and (if you're playing career mode) cost.  Admittedly, there's a pretty big gap in the payload spectrum where the Swivel is not big enough, and something like the Skipper is too big.  It might be possible to find another arrangement that gives you the needed attitude control with a little more efficiency.  A few ideas (with the caveat that I'm not sure of your tech tree level or mods):

  • Central Svivel with a couple SRBs for extra launch thrust
  • Central Reliant with a couple Spiders or Twitches on the side (this is surprisingly effective, and quite a bit cheaper than fins)
  • A couple of Thuds, with either nothing under the middle or something like the Spark.
  • Just use the Swivel on smaller rockets - this might be viable for your revised rocket.  Its sea level thrust and ISP are pretty bad, but if you can put up with that for a few seconds, it gets up into the tolerable range fairly quickly.
  • Try smaller/cheaper fins, like the smallest elevons.  With a stable rocket it should not take much control authority to keep it on track.  

I'll keep that in mind.  While the mass shouldn't be an issue (since that would be reflected in dV numbers), it's possible that an excess of drag is causing me to burn up more dV than I should be burning up. 

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9 hours ago, Landwalker said:

For some reason my crafts seem to be... not very cooperative.  Some of this is obviously on me (see Piloting Issues #2).  Some of it is probably also on me, except that I don't know exactly what it is.  This includes things like my upper stage cartwheeling out of control, for example.  Unless I know why things happen, I can't fix them.  :/

Part of the problem is that on both rockets you posted the first stage is burning short and violently. This means you will stage early while still being deep in the atmosphere and at a breakneck speed. And you know that a stable rocket has a CoM relatively high up and more drag behind the CoM than in front of it. When you stage the CoM will suddenly go to the back of the remaining rocket (because of the fuel and heavy engine of course) which gives the aerodynamic forces more leverage to work against you.

The solution would be to have your first stage running long enough to get you out of the thickest part of the atmosphere. Both of your rockets have enough TWR to easily carry much more fuel.

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55 minutes ago, Harry Rhodan said:

Part of the problem is that on both rockets you posted the first stage is burning short and violently. This means you will stage early while still being deep in the atmosphere and at a breakneck speed. And you know that a stable rocket has a CoM relatively high up and more drag behind the CoM than in front of it. When you stage the CoM will suddenly go to the back of the remaining rocket (because of the fuel and heavy engine of course) which gives the aerodynamic forces more leverage to work against you.

The solution would be to have your first stage running long enough to get you out of the thickest part of the atmosphere. Both of your rockets have enough TWR to easily carry much more fuel.

The first stage isn't actually burning that violently (you know, by controlled explosions standards).  I artificially ran it at a lower TWR (around 1.8 - 2.0), stretching out the burn.  My concern isn't "Do I have enough TWR to carry more fuel," it's more "Given my calculated dV, I should be able to get this thing into orbit, but can't."  Certainly, if I wanted to, I could just grossly overbuild and get a 5,000 dV craft packed with fuel into orbit every time.  But that would be inefficient and expensive, and I'm trying to avoid inefficient and expensive solutions to my already inefficient and expensive problem.

The COM issue, though, is one that I was wondering about this morning.  I didn't have time to test anything before work, but tonight I'll try reducing decoupler strength (and/or maybe using a stack separator instead, and/or using some sort of fueled-decoupling solution) and also paying more attention to the upper stage's COM.  

Given that I'm already throttling back my TWR to prevent it from going crazy, I may also try replacing the Reliant with a Swivel and scaling back on the stabilizing fins.  Hell, I might throw out the second stage engine entirely and try to do the whole thing with just a single launch stack (and maybe a couple of small SRBs if extra oomph off the launch pad is necessary).

 

Honestly, at this point, I would probably benefit most from seeing examples in action.  I've tried to find some videos, but the ones I found were both not very recent at best (clearly outdated at worst) and not very design/profile/mission-efficient (things like "Oh you can get up in 3500m/s but I'm not going to because this is just an example of getting up at all," or overbuilt 2.5m single-stage stuff).  If anyone has (or is willing to create) examples in action, especially if they are similar in spirit to my original design effort (the spirit being a launch system to deliver a small prove into low orbit, and then deorbit and recover it), I would much appreciate it.

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2 hours ago, Landwalker said:

Well, as-stated, I clearly am doing something wrong.  Knowing that I'm doing something wrong, however, without knowing what that something is, is not as helpful as people seem to think it is.

While there is a few possible design flaws I don't see nothing severe enough to take the amount of losses you are experiencing. The only sensible explanation seems to be piloting.

Either try to better describe how tlyou are flying,  (e.g. what speed, altitude, inclination you are getting at time of staging and at some ballparks (5km, 10km, 20km)).

You can also share a craft file, so people can test it and see if they can put it in orbit for dobsiserable less and explain what they did.

Edited by Spricigo
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When piloting practice is an issue, I always like to point the student towards my favorite training craft - a simple rocket SSTO. It's a bit of a contrived case, since you usually wouldn't go single-stage in actual gameplay, and it actually introduces a bit of extra complexity... but for training, I find that to be advantageous.

Build the following: a mk1 pod, a parachute on top, a 1.25m decoupler, two of the largest stock 1.25m tanks, and a swivel engine. Nothing else, not even fins.

Your training mission: place a Kerbal into orbit around Kerbin, and return him safely to the surface. (I recommend taking a rookie pilot Kerbal.)

Pulling this off requires a good trajectory, so you can reach orbit with fuel to spare for the deorbit burn. At the same time, you will find that staying on a good trajectory will be hard, because your rocket goes from crawling off the pad with just enough TWR, to being ridiculously overpowered near the end of the burn. Normally, staging in mid-ascent bumps your TWR down for you automatically. With this rocket, you have to do it yourself. This is an exercise in manual steering and throttle control, combined with awareness of where you are in your ascent, where your apoapsis is, what your current pitch is, and how fast you are currently going. It will likely take you multiple tries.

(You may choose to limit or disable to gimbal on the Swivel if you feel that the craft reacts too violently to steering input, but it shouldn't strictly be necessary.)

1 hour ago, Landwalker said:

Honestly, at this point, I would probably benefit most from seeing examples in action.

I've never actually recorded, edited or uploaded video, but I suppose I could try taping a demo flight for you.

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This is probably quite a rookie method, and is probably not a very good idea, but as an orbit noob it works quite well for me :)

1) Just launch straight up. This is convenient as there are no worries with turns or anything

2) Keep going until you're happy with your apoapsis. I usually go until my first engines fall off. At this point it is usually around 70k. Normally you end up with an orbit around 20k higher however.

3) When you're happy, tilt a full 90*. I usually set a manoeuvre just to know how much dV I need is left

4) Start burning almost immediately.

Unfortunately it takes some time (around 5 minutes) and im trying to use the more traditional way, but its fairly reliable for beginners xD     

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1 hour ago, Streetwind said:

When piloting practice is an issue, I always like to point the student towards my favorite training craft - a simple rocket SSTO. It's a bit of a contrived case, since you usually wouldn't go single-stage in actual gameplay, and it actually introduces a bit of extra complexity... but for training, I find that to be advantageous.

Build the following: a mk1 pod, a parachute on top, a 1.25m decoupler, two of the largest stock 1.25m tanks, and a swivel engine. Nothing else, not even fins.

Your training mission: place a Kerbal into orbit around Kerbin, and return him safely to the surface. (I recommend taking a rookie pilot Kerbal.)

Pulling this off requires a good trajectory, so you can reach orbit with fuel to spare for the deorbit burn. At the same time, you will find that staying on a good trajectory will be hard, because your rocket goes from crawling off the pad with just enough TWR, to being ridiculously overpowered near the end of the burn. Normally, staging in mid-ascent bumps your TWR down for you automatically. With this rocket, you have to do it yourself. This is an exercise in manual steering and throttle control, combined with awareness of where you are in your ascent, where your apoapsis is, what your current pitch is, and how fast you are currently going. It will likely take you multiple tries.

(You may choose to limit or disable to gimbal on the Swivel if you feel that the craft reacts too violently to steering input, but it shouldn't strictly be necessary.)

I've never actually recorded, edited or uploaded video, but I suppose I could try taping a demo flight for you.

Im playing RSS at the moment and while im sending probes to Mars and just about to launch my version of the Cassini - Huygens mission to Saturn im going to set up a stock install and try your training mission.....im sure I will learn some important facts about my launch procedure which is great as learning KSP is a daily requirement :)

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31 minutes ago, MajorMushroom said:

This is probably quite a rookie method, and is probably not a very good idea, but as an orbit noob it works quite well for me :)

1) Just launch straight up. This is convenient as there are no worries with turns or anything

2) Keep going until you're happy with your apoapsis. I usually go until my first engines fall off. At this point it is usually around 70k. Normally you end up with an orbit around 20k higher however.

3) When you're happy, tilt a full 90*. I usually set a manoeuvre just to know how much dV I need is left

4) Start burning almost immediately.

Unfortunately it takes some time (around 5 minutes) and im trying to use the more traditional way, but its fairly reliable for beginners xD     

This is actually a bad way imo to do it.....it "used" to work well however as KSP has evolved so much that I feel the best thing to do is attempt gravity turns much earlier. I am myself going to be testing my launch profile using @Streetwind 's test mission as I believe your launch is one of the most important parts of any mission.

** apologies for the double post **

Edited by maceemiller
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Okay...taking a look at the Circe, and some of the advice you've already received on this thread.

Just at a glance, @HvP is spot-on when he pointed out you're not in atmo mode on KER (the button that says "Atmospheric"). Turn it on and leave it on - KER these days is smart enough to know which bodies have atmo and which ones don't. You may find that you don't have nearly as much delta-V as you think you have.

The launch TWR on that craft is nuts; you're going to lose a lot of your first-stage delta-V to drag. I use FAR; with FAR, a good launch TWR is 1.2-1.3. With stock air, a good launch TWR is 1.5 or so (at least it was last I checked; the old 1.6-1.7 rule may still apply). As you're flying along, watch your gee meter - if it climbs out of the green at any point, that's a cue to throttle the engine back. You don't need to change out the engine - just play with the throttle limiter until you get a TWR in that range. You can always swap out the engine later if you need to, and you can always adjust the throttle limiter more in flight if you feel it necessary to do so.

The second-stage TWR is not high enough; KER is telling you that much. You've got a 25 kN engine trying to push a 3.5 tonne craft when that stage lights - a TWR of 0.7 at that point. You're losing delta-V to gravity at that point. Your second craft has rectified this somewhat, but you're saying it's giving you control headaches. Would you mind taking a screenie of just that stage with your control balls on (CoM, CoL, CoT)? Wagering your CoM is too far aft on that stage. TWR is still a tad on the low side for that stage of the ascent.

Since I use FAR, I can't really give you good advice for the earlier portion of the ascent (while there's still atmo). The last I'd heard was to try to cross 45 degrees elevation at 15,000 meters. I have benchmarks for the latter portion of an ascent - 20 degrees above the horizon at 25,000 meters, with 35 seconds to apoapsis; 15 degrees/30,000m/40 seconds; 10 degrees/35,000 meters/45 seconds to apoapsis; 5 degrees/40,000 m/50 seconds; horizon/45,000m/55 seconds; five degrees below/50,000/1m 5s to apoapsis, and then ride that until the apoapsis is where you want it +1000 meters for every 1000 meters below 60,000 your altitude is at MECO, or +100 meters for every thousand meters if MECO is between 60-70k). Usually results in circularization burns of 50-70 m/s at most. Whether or not that's actually a good profile, I can't say; I can say that it works for me.

Good luck; let us know how it's going.

Edited by capi3101
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@maceemiller As an experienced player, you may not find yourself suitably challenged by this :wink: The craft is actually quite lenient in the dV department, in order to not frustrate newcomers too much. I just made a half-assed attempt that went a bit too steep - the first time I've flown this thing since the Swivel had its thrust uprated - and I still had 380 m/s left once in a 73x73km orbit.

If you want to make it a bit more challenging, add a heatshield. That should roughly halve the margin.

Edited by Streetwind
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8 minutes ago, Streetwind said:

@maceemiller As an experienced player, you may not find yourself suitably challenged by this :wink: The craft is actually quite lenient in the dV department, in order to not frustrate newcomers too much. I just made a half-assed attempt that went a bit too steep - the first time I've flown this thing since the Swivel had its thrust uprated - and I still had 380 m/s left once in a 73x73km orbit.

If you want to make it a bit more challenging, add a heatshield. That should roughly halve the margin.

Then I think I will add one :) ive never really tested my launch....yes ive got better at it but never actually tried to "better" it so I find this test quite appealing as it will certainly make me improve my RSS install :)

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22 minutes ago, MajorMushroom said:

This is probably quite a rookie method, and is probably not a very good idea, but as an orbit noob it works quite well for me :)

1) Just launch straight up. This is convenient as there are no worries with turns or anything

2) Keep going until you're happy with your apoapsis. I usually go until my first engines fall off. At this point it is usually around 70k. Normally you end up with an orbit around 20k higher however.

3) When you're happy, tilt a full 90*. I usually set a manoeuvre just to know how much dV I need is left

4) Start burning almost immediately.

Unfortunately it takes some time (around 5 minutes) and im trying to use the more traditional way, but its fairly reliable for beginners xD     

the issue he is facing is not that he is not reaching orbit but that he is using too much fuel to reach orbit.

That method would makes his problem worse.

Also, I strongly recommend that you stop using it immediately since you can be much more efficient even with a badly performed gravity turn.

 

Quote

1) Just launch straight up. This is convenient as there are no worries with turns or anything

Sorry, but the idea that a gravity turn is in some form worrisome to pull out is just wrong.  I can tell from my experience , doing a reasonable gravity turn is not only easy but trivial to perform.

About 60% of my gravity turn are done like: 1. press space(to launch) 2. press space(to drop booster) 3.wait for apoapsis

The rest are like: 1. press space(to launch) 2.set SAS to follow prograde 3. press space(to drop booster) 4.wait for apoapsis

That's it, 2-3 key-presses/clicks and you go to orbit for less than 3,5km/s.

It can be made even more efficient with some extra care for details, but most of the advantage can be achieved with a 'lazy' gravity turn like that. The only thing that is missing in your firsts attempt are the knowledge to know how much of a initial turn is required (/muscular memory for those that prefer the 'nudge' method.)

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