Your Unusual Tricks of the Trade

[Corona688]

19 minutes ago, monstah said:

Just to clarify: you get 2 * sin(45º) ~ 1.4x the thrust of a single thruster, but you spend 2x the fuel, so for each thruster you only get sin(45º) ~ 0.7x the total thrust for that thruster.

Yep, I knew it was less efficient.

19 minutes ago, monstah said:

If you think, however, on a '+' configuration they also fire in pairs

Not quite what I mean.  The top two nozzles of an X would fire for up/down translation, for example, two nozzles on both sides.

[monstah]

23 minutes ago, Corona688 said:

Not quite what I mean.  The top two nozzles of an X would fire for up/down translation, for example, two nozzles on both sides.

Yeah, you're right. There are actually four firing, not two, so you do get 2x the thrust. My bad  

[HalcyonSon]

Adding this before I forget...  Heat shields block fuel flow if placed between a tank and an engine, but you can use the move tool to make a gap and then add a fuel line from the tank to the heat shield.  The fuel line will be hidden when you use the move tool to close the gap.  An engine placed on the inner heat shield node (without the fairing) will now pull fuel from the tank on the other side of the heat shield.  

My typical one-Kerbal rescue pod includes a top parachute, a few radial parachutes, a capsule without monoprop, a service bay with batteries and probe core, a small fuel tank, a fuel line, a heat shield with about half ablator, and a small rocket motor.  Everything returns to Kerbin for maximum funds.  (Main booster LFO tanks are dropped back into atmo before the rescue)

Edited September 28, 2016 by HalcyonSon

[HalcyonSon]

On 6/20/2016 at 0:30 PM, Cornholio said:

Similarly, I always flip/offset batteries inside of command modules/fuel tanks/everything because it looks better and I think it's ridiculous to see a rocket with a big AAAAAA battery hanging off of the side.

I will do this with the in-line 2.5m to 1.25m adapters.  Cram them full of useful stuff, otherwise I feel like they're a huge waste of space and mass.  My reasoning is that they're essentially empty space with only a small volume dedicated to actual structure.  

On 6/20/2016 at 2:01 PM, Fearless Son said:

Speaking of tall boosters, never use the "Kickback" without strutting it first.  The tallness, heavy mass, long burn time, and high thrust of this can lead it to introduce some harmonic forces while performing even a gentle lateral maneuver (it "wiggles" a little.)  This in turn can cause you to easily loose control of the rocket, particularly because there is no way to throttle down solid boosters once they are lit.  Struts will increase the air resistance of the craft, true, but a carefully placed strut or two should get rid of the worst of the harmonic forces without significantly impacting total delta-v for the ascent stage.  

Best to use a radial decoupler at the top of the Kickback, and a strut at the bottom.  Then staging gives the Kickback a bit of rotation that helps it clear the center stack.

On 6/20/2016 at 7:20 PM, StrandedonEarth said:

I haven't used sepratrons on Kickbacks for a long time. Place the decoupler high, using the gizmo to slide the SRB down so the nozzles are beside or below the main engines. Place the struts low. The decouplers will kick the top of the Kickback away, while the bottom will already be past the main engines

Ha - what he said.

[DerekL1963]

If I'm building a nuclear powered vehicle that needs to dock...  If I can, I put the LV-N's on radials.  That way you I slide the radials up and down the body of the craft and get my Wet, Dry, and Average COM practically on top of each other, making it much easier to balance the RCS.  (Actually, this does work with non-nuclear powered ships, it's just particularly effective in this case due to the LV-N's huge mass.)

Edited September 28, 2016 by DerekL1963

[quasarrgames]

-Stacking ISRU converters gives you more fuel with the same amount of ore

-Radiators are OP when it comes to aerobraking, just be sure to mount them on the front and back of your ship so it doesn't flip due to drag

[Curveball Anders]

I use common sense, random knowledge in math and  physics and repeated reverts.

It's been my unusual trick from day one

[Aegolius13]

-Putting fuel in "hats."  Sometimes you want to discard your spent fuel tanks, but don't want to have to include an extra engine, or mess around with radial tanks or engines.  The solution: put a detachable tank on the top of your ship. You may have to stop your burn for second and turn a bit to detach the hat, but that's usually not a big deal.

-On very large launches, I have taken to adjusting the SRBs so they burn out at the same time as the first stage of LF boosters.  That way, you can just attach the SRBs right onto the booster, and forget about extra decouplers or struts.  Of course, when doing this you lose a ton of thrust when the whole thing detaches.  But it works well with Rhinos set to kick off on the next stage.  

-Whenever helpful, sprinkle in a little radial burn to a prograde/retrograde burn, or vice versa.  It's practically free due to the Pythagorean nature of burn vectors.  A good example is when you're adjusting your perisapsis as you enter a new SOI.  

 

[Kobymaru]

16 hours ago, quasarrgames said:

-Stacking ISRU converters gives you more fuel with the same amount of ore

Wait, what? How is that possible? That's gotta be a bug.

 

7 hours ago, Aegolius13 said:

-Whenever helpful, sprinkle in a little radial burn to a prograde/retrograde burn, or vice versa.  It's practically free due to the Pythagorean nature of burn vectors.  A good example is when you're adjusting your perisapsis as you enter a new SOI.  

I'm not entirely sure about this, but my mathey-spider-sense tells me that this is not how it works. I might be wrong, of course.

 

But it reminds me of my own "trick":

When entering an SOI (or way before that), align the Periapsis marker of the hyberbolic trajectory to be on the same plane as whatever you want to rendezvous with (say, a station in that SOI, or an inclination plane you want to end up in).

Then burn at that apoapsis only so much that you get a capture, but do not circluarize. Then, on the apoapsis of the highly elliptical "barely-captured" orbit, changing inclination is incredibly cheap.

No more paying *TONS* of m/s for changing plane after capture.

Edited September 29, 2016 by Kobymaru

[monstah]

8 hours ago, Aegolius13 said:

-Whenever helpful, sprinkle in a little radial burn to a prograde/retrograde burn, or vice versa.  It's practically free due to the Pythagorean nature of burn vectors.  A good example is when you're adjusting your perisapsis as you enter a new SOI.  

I'd add that one should really practice and experiment with radial and prog/retro, and their combinations. For example, when I'm adjusting my reentry Pe from a high orbit (Mun return, for example), I find that burning toward the horizon (in the tangential plane, a.k.a. the prograde-radial-retrograde-antiradial one) seems most effective than either direction alone. Radial also allows you to change the longitude of Pe (SCANSat and Trajectories are great for predicting this), so you can roughly adjust your landing zone from way up there.

32 minutes ago, Kobymaru said:

I'm not entirely sure about this, but my mathey-spider-sense tells me that this is not how it works. I might be wrong, of course.

You mean the part of it being 'free', or the part where you need to add it? Well, he's right on it being 'free': if you're doing say a 100m/s prograde, you can add in 30m/s radial and your total burn will have increased by less than 5m/s. Just do the pythagorean triangle and see for yourself  As for the utility of doing that, it depends on the situation.

[Kobymaru]

14 minutes ago, monstah said:

You mean the part of it being 'free', or the part where you need to add it? Well, he's right on it being 'free': if you're doing say a 100m/s prograde, you can add in 30m/s radial and your total burn will have increased by less than 5m/s. Just do the pythagorean triangle and see for yourself  As for the utility of doing that, it depends on the situation.

I know the pythagorean triangle, thanks  My question is: do you rotate the orbital plane by the same amount if you burn *only* 30 m/s radial, or if you add them to a prograde burn.

 

Now I identified my mental discomfort with that idea: how exactly is energy conserved? In one case, I rotate the orbital plane, in the other case I rotate the orbital plane AND raise the apoapsis/periapsis, with almost no additional dV? Something doesn't seem quite right here.

Edited September 29, 2016 by Kobymaru

[DerekL1963]

3 hours ago, Kobymaru said:

But it reminds me of my own "trick":

When entering an SOI (or way before that), align the Periapsis marker of the hyberbolic trajectory to be on the same plane as whatever you want to rendezvous with (say, a station in that SOI, or an inclination plane you want to end up in).

Then burn at that apoapsis only so much that you get a capture, but do not circluarize. Then, on the apoapsis of the highly elliptical "barely-captured" orbit, changing inclination is incredibly cheap.

No more paying *TONS* of m/s for changing plane after capture.

Honestly, I do pretty much all my plane change burns right after entering the target SOI, they're incredibly cheap out there and it gets the burn out of the way.   This is especially important at Kerbin, Duna, and Jool where there are moons to worry about.  (Especially at Duna.)

[monstah]

2 hours ago, Kobymaru said:

I know the pythagorean triangle, thanks  My question is: do you rotate the orbital plane by the same amount if you burn *only* 30 m/s radial, or if you add them to a prograde burn.

 

Now I identified my mental discomfort with that idea: how exactly is energy conserved? In one case, I rotate the orbital plane, in the other case I rotate the orbital plane AND raise the apoapsis/periapsis, with almost no additional dV? Something doesn't seem quite right here.

I never said you didn't, sorr if it sounded so  anyway, when you rotate the orbit, you also change Ap and Pe, which counters a bit of the prog/retro burning, so it's not a magical solution. If you're at Ap, the cheapest way to lower Pe is burning retro, no way around that (but then, in that case, retro is toward the horizon...). But if you're in the mid of a drop, playing with both retro and radial lets you change Pe altitude and longitude by marginally more than you would adjust only its altitude burning purely retro.

[Sharpy]

On 18.09.2016 at 3:04 AM, Aperture Science said:

This thread title, though.

WARNING: Has a tiny bit of flashing colors

  Hide contents

I'm so sorry for the Comic Sans

A thousand? Smalltime!

40 ISRUs. 80 gigantors. 120 large ore tanks, full. 480 large monoprop tanks, empty. 5 largest radiators. 40 launch clamps, so that the runway won't explode under the mass. One stayputnik. One action group to start it all up.

It costs around a million when deployed in the morning. It sells for 1,3mln in the evening.

I'm playing career for the challenge of leveling up kerbals and having varied levels of probe cores. I do contracts I find interesting. I don't slave away with boring, stupid contracts to scrape money for actually interesting stuff.

[Nich]

Put LFO tanks on top of your solid boosters with fuel lines to your central core.  Size the tank so that it runs out when the booster runs out or just after.  This way when you stage you have a full center core.

[Aegolius13]

3 hours ago, monstah said:

I'd add that one should really practice and experiment with radial and prog/retro, and their combinations. For example, when I'm adjusting my reentry Pe from a high orbit (Mun return, for example), I find that burning toward the horizon (in the tangential plane, a.k.a. the prograde-radial-retrograde-antiradial one) seems most effective than either direction alone. Radial also allows you to change the longitude of Pe (SCANSat and Trajectories are great for predicting this), so you can roughly adjust your landing zone from way up there.

You mean the part of it being 'free', or the part where you need to add it? Well, he's right on it being 'free': if you're doing say a 100m/s prograde, you can add in 30m/s radial and your total burn will have increased by less than 5m/s. Just do the pythagorean triangle and see for yourself  As for the utility of doing that, it depends on the situation.

As an example, say you're coming out of a Tylo gravity assist and about to aerobrake at Laythe.  Generally a radial burn would be the cheapest way to lower your peri to the desired altitude.  But it has the side effect of increasing your velocity at peri, which can make the aerobrake dangerous.  Or you can burn retrograde, which will bring down both ends of the orbit, but is not a very efficient way to bring down peri if you're close to peri.  In that situation, seems like you can get a small advantage by adding a small retrograde burn to your radial burn.  Not saying it's a big savings, but every little bit can help.

[Archgeek]

49 minutes ago, Sharpy said:

A thousand? Smalltime!

40 ISRUs. 80 gigantors. 120 large ore tanks, full. 480 large monoprop tanks, empty. 5 largest radiators. 40 launch clamps, so that the runway won't explode under the mass. One stayputnik. One action group to start it all up.

It costs around a million when deployed in the morning. It sells for 1,3mln in the evening.

I'm playing career for the challenge of leveling up kerbals and having varied levels of probe cores. I do contracts I find interesting. I don't slave away with boring, stupid contracts to scrape money for actually interesting stuff.

Pics or it doesn't happen regularly.  

Edited September 29, 2016 by Archgeek
Wandering appostrophe

[Sharpy]

@Archgeek Okay, I lied.

40 stayputniks.

I couldn't be assed to remove the extra ones.

This is still before I added the radiators - as effect ISRUs would be thermally throttled and the whole cycle lasted 2 days instead of one. Only 5 of the largest radiator panels sufficed. Adding action groups to that thing is a pain. Also, I forgot about the Kerbodyne bases. Seriously, the most serious concern (beyond having the tech tree unlocked and a million for startup) is structural. Without these clamps the runway stands no chance.

Actually, it doesn't happen too regularly. In current career, I used it twice, producing 2mln each time. The second time I was actually in a pinch, I got down to some 600,000 on funds. I took a "build a base on Gilly" to be able to afford this. I'm still waiting for a launch window for that base.

Edited September 29, 2016 by Sharpy

[Sharpy]

15 hours ago, Kobymaru said:

I

Now I identified my mental discomfort with that idea: how exactly is energy conserved? In one case, I rotate the orbital plane, in the other case I rotate the orbital plane AND raise the apoapsis/periapsis, with almost no additional dV? Something doesn't seem quite right here.

Using conservation of energy in rocketry can be deceitful. The problem is the reaction mass, which you infuse with energy too, and which you can infuse with energy uselessly.

Energy=work=force*distance. If you artificially lengthen the distance by following two sides of a rectangle instead of the diagonal, you will expend more energy than through the shortest path, for the same reason. And conservation of energy? The extra energy went into accelerating more of propellant in two less useful directions.

Another way to think of it: build a rocket with two engines, both facing 45 degrees from the flight axis in opposite directions (a'la LES) instead straight "backwards". Compare the effect with a plain bicoupler solution.

 

[Papa BullDust]

A couple of tips for when you want to align two vessels for docking, let's say a station and a small craft, and you've got within say 100 or so metres with approx 0 relative velocity.

First, 'switch to' the station and if the docking port to which you wish to attach the approaching craft has a symmetry partner, i.e. a docking port facing the other way, simply 'control from here' on that partner docking port and note which way the centre of the navball faces. This will be the exact direction the incoming craft must face in order to align with the intended docking port.

So switch back, and do the usual things (control from the small craft's docking port, set the station port as the target) and of course, align the craft so it faces the direction you noted. It's then just a matter of drifting slowly towards the station, translating with IJKL+HN (or docking mode) using the prograde marker to 'pull' the target marker under the centre of the navball.

Success! (Disclaimer: success is not guaranteed)

Similarly, if there is no symmetrical partner docking port, 'control from here' on the port where you plan to dock, note its direction, and envisage the other side of the navball.

Since the navball has numbers to show you how many degrees radial (into the blue or brown halves) you're pointing, and how many degrees 'round' the navball you point e.g. 0 degrees being North, East at 90 etc., these can help to picture the opposite side.

This comes quite naturally after a few tries, I find myself only needing to note two directions, for example, say the station port was facing 20 degrees into the blue half of the navball and at about 225 degrees round. I face 20 degrees into the brown half facing 45 degrees (taking 180 from 225 as there are 360 degrees round... you know this) It can be as simple a thought process as that.

This is quite a niche tip as, for a lot of rendez-vous situations, you could just eyeball the alignment. This trick is really if you need to be more exact (bigger craft, less wiggle room in the docking alignment) or you, like me, are rubbish at and/or dislike guestimating.

Lastly of course, you could just install the Community NavBall Docking Alignment Indicator mod.

[RoboRay]

5 hours ago, drewthedrewman said:

A couple of tips for when you want to align two vessels for docking

Easiest way is to align both craft along the Normal axis, with one docking port pointed Normal and the other Antinormal (north and south right on the horizon line, if you're in a typical equatorial orbit).

In addition to ensuring that both craft are oriented properly for docking, it also eliminates the apparent rotation and displacement of the target craft caused by the curved orbital paths around the planet.

Edited September 30, 2016 by RoboRay

[DrLicor]

@drewthedrewman, in my opinion, this is the best docking tutorial:

 

[Papa BullDust]

16 minutes ago, RoboRay said:

Easiest way is to align both craft along the Normal axis, with one docking port pointed Normal and the other Antinormal (north and south right on the horizon line, if you're in a typical equatorial orbit).

In addition to ensuring that both craft are oriented properly for docking, it also ensures that they stay oriented properly as it eliminates the apparent rotation of the target craft caused by their curved orbital path around the planet.

Absolutely, this is by far my most commonly used method. The trick I outlined is really only necessary if one of the docking vehicles is a large station that might not stand the stress of being re-aligned each time a ship needs to dock. Really quite niche indeed! (Which pretty much negates the whole 'written for new players vibe I was going for. I really should think more before I post... :p)

 

@DrLicor Heck yeah man, Scott Manley was my staple go-to in the early days, and this tutorial in particular stands the test of time.

 

[monstah]

The locked camera, to me, makes docking so easy I don't even think about it much. Just put the camera facing in the same direction as the dock and go.

[Sharpy]

How to separate radial boosters cleanly without use of any extra parts? No separatrons, no winglets, decouplers can be as weak as you like.

Put your craft in a spin before separation. Just hold Q for a while. Centrifugal force will eject the radial boosters more cleanly than any other "aid".