[The Antship Challenge]

The challenge seems restricted. I think people would still desire mission freedom, so to land at as much places as possible.
Why require a Mk1-3 command pod then? I think it's better in terms of rules to say a mk1-3 command pod is used to transfer the kerbals interplanetary but can use a command chair to land on Vall, Bop or any place.

For one thing, I don't understand how a single ant can lift a mk1 lander can from Moho, or is it the goal to get to a stable orbit?
If this is the case then the challenge offers very little creativity, just how good one is at orbital maneuvring and packing enough Dv.

[Fly by IVA (Yeah - I'd Buy a DLC for This)]

Yes, although interior spaces are quite small so there's little maneuvring room unless you build a space station.

There is a mod called Omicron Flying space car that has a cockpit with window shutters and the interior seats are actual seats you can board. To my mind something like that could work. You wouldn't have to fiddle with interiors as the cockpit itself is an interior.

You could have certain handles, one on the hatch to hang unto on the inside in order to exit the ship, or floor ladder like on the omicron mod so you can crawl up or down to another module.

Modules that are connected to one another, for instance a hitchhiker to a mk1-2 command pod would have a editor option to remove the floor or have a 1.25m opening to drift through, so behind the seats in the Mk 1-2 command pod should get a hole if the editor function was used.

[KSP Interstellar Extended Support Thread]

I try using the VASIMR engine, but it's thermal efficiency keeps dropping even although radiators are installed. I can't figure out how much radiator it needs but I tried to stuck on a bunch.

I'm using a Magnetized fusion power reactor and a generator and the VASIMR thermal efficiency keeps dropping. I can't understand why? I probably don't know all the prerequisites, does anybody know how to properly operate the VASIMR>

[keeping rotors in sync.]

By the looks of it a rotor doesn't have infinite torque as it lags as the legs hit the ground. This is probably good since infinite torque would be bad when used on bearings used on props or other things. Why not attach both left and right legs to one rotor and then drag it to the proper spot?

By all means, max rotor torque should mean very high amounts of torque. Maybe have a near infinite torque setting at max setting with a exponential magnitude towards zero torque on the lowest setting. Although it may make calibration finicky so it may not work properly.

[Tips on building airliners?]

On space planes you can try to do the following to synchronize CoM and CoT.

Use Move:Tool to move the engines further up or down only if they're attached radially. This moves the dry/wet CoM up or Down so the CoM is aligned with the CoT. Use a ruler on the screen to see if it's aligned perfectly. If it isn't you can move radial attached fuel tanks up or down for the same effect, or move the contents of a cargo bay further up or down to calibrate the CoM and CoT further. You said you haven't installed cargo yet, installing it might help especially when attached to the bottom of the cargo bay to move the CoM further down towards the engines.

In your case the engines a very much down so the CoT is below the CoM quite a bit, no wonder you have control issues. Try to create a wing with the structure at the top with the engines hanging there under on pylons. Or attach the engines on top of the wing.

For flexing wings it is best to attach the end segments directly to the fuselage and then drag them to the tip. If you have multiple wing segments you get a lot of flexing and at some point even autostruts wont fix this.

On 5/31/2019 at 9:07 AM, Actually_New_KSP_Player said:

not enough lifting surfaces to push CoL closer to the CoM etc

Use more lifting surfaces... What would stop you from doing so?

[Fuel tanks wont connect]

I know there's a editor bug that if you select a new fuel tank you sometimes have to drag and drop it and then pick it up again. Sometimes one or both nodes are not activated but they'll reactivate by dropping the tank and then picking it up with the LMB again.

[Is there any chance I can let my rocket that has been tipped over back up on the moon?]

Create a rover with a Airbrake mounted horizontal at the front while sticking out, make sure it's rotated that extending it makes it move upright. Think about a forklift action using the airbrake and then add it to a action group. Also make sure the rover is not to light otherwise it won't be able to lift the lander.

Get the rover to the moon, drive the airbrake under the fuselage and use the action group to extend and hopefully upright the lander. If it fails try again until you succeed, plus point is that you now also have a rover on the Moon. So make sure you stuff it with anything useful like science or other goodies if your intention is to have a rover on the moon on future missions.

 

[Unequal air distribution]

That particular intake isn't very good for super/hypersonic speeds. Some of them will reduce feed intake air as speed increases as these intakes are meant for sub/transonic speeds. You can still use any of the air intakes like the ones used at those speeds but it fails to intake all the air it could on lower airspeeds.
Also, intake air is proportional to speed. So if you were going faster then 900+ m/s at 11km altitude you'd last longer.

In your particular design I would use the Adjustable ramp air intake. You will need quite a few of them, what's wondrous about them is that they're very lightweight and very aerodynamic. They aren't very heat resistant, however, attaching them on the top will cause heat friction to be absorbed at the front so these intakes should be protected from heat as long as you keep the nose up during aerobraking.

You could also re-design the ship, remove one Mk2 fuel tank in the middle or use a shorter one, then use the other Mk2 inline cockpit and use a mk2 to mk1 adapter with a shock cone intake at the front and remove the other intake at the back.

[Are we still pretending the wheels/legs aren't broken?]

Airbrake is a anchor in the ground. The landing gear suspension pushes back upon ground contact but then retracts because it is programmed to balance the suspension based on the other legs. Since the craft is on a slope the retracting suspensions lowers the back, because the craft pivots at the airbrake the lowering back will suspend backward as the legs suspension extends and retracts, at least this is what I think is going on. What is silly is that the legs suspensions want to compensate while the craft isn't upright. What would be good is for the game to read the craft legs are sideways so the suspensions will stop balancing.

AFAIK this method is used to create cannons to shoot capsules into orbit or space, some KerbalX crafts use this as "kraken" drives.

[Multi Minmus Launch]

Even if you were to do SSTO, if you want to win the challenge a stageable rocket gets you a lot further anyway, so why choose a SSTO in the first place?

[Action group overview.]

In stock KSP you normally set action groups for your vessel and then you have to write down the set action groups for you to remember what they are. Of course, this can be done... Otherwise you could use "action groups extended" mod. You wont always want this because you want to have a stock game making stock craft.
In stock KSP you won't have any in game notification what part action groups you set under 0 through 9.
Therefore, maybe the stock game could use a in build function attached to the toolbar or anywhere else for that matter so you have information how action groups are setup.

[Extended Center Of Thrust Line / options]

Very good suggestion, always wanted this, strange I haven't suggested this before myself.

Another thing, Sometimes i have cargo and a engine inside a service bay that is added to the alignment of the center of thrust indicator while it isn't part of the propulsion system to which the purple arrow should be drawn from.

So engines that aren't part of the 1st stage and can't produce thrust because they're blocked inside a service/cargo bay shouldn't be added to the thrust vector the Center of thrust indicator calculates.

'

[How to get power to communotron antenna]

You might accidentally pressed the icon next to the electricity content when right clicking the battery in the editor by mistake perhaps. When you do you cancel the battery from draining energy, it might be an oversight

[Is Squad planning to change campaign gameplay?]

11 hours ago, Fraktal said:

And for your very first solid-fuel rocket, it can be used as a crude decoupler. Firing an RT-5 directly into it overheats and destroys the girder in less than a second even at 20% power, allowing multistage rockets even before you unlock the actual decoupler part. One such design I whipped up consists of six RT-5s on the first stage, then a girder, then a single RT-5 on the second stage set to 20% power. It can reach nearly 40 km altitude, but of course is very hard to control on the way down and cannot slow down to parachute release speed merely by flying retrograde.

Of course, you won't be able to decouple the last booster this way, unless you waste weight on mounting an RT-5 upside down.

AFAIK the RT-5 booster get's destroyed on impact and the command pod usually survives because the first part took all the impact so the 2nd part survives. Using a 2nd RT-5 to knock of the last stage then seems kind of pointless.

[SM-25 Service Module: What for?]

The SM-25 seems to be very "Hydrodynamic"
Besides boats it seems to have a low to medium submerge ability meaning it doesn't have that much positive buoyancy. Meaning it requires not that much negative ballast to submerge.
Since everything inside is protected from drag you can stuff the content with seats, vectors or ore ballast and tbh really anything else and can do 60+ m/s underwater with proper tapered ends instead of 50m/s I could achieve on older stock designs without the SM-25 used. Put a stock impeller behind and you have a infinite range and fast submarine.

[What feature do you want for 1.8?]

KSP isn't a record holder game so don't we all think it deserves money, AFAIK it is the game with the most hours, if that's true in your or any case would you still want a free DLC? IIRC all DLC's of other games cost money, so why is KSP a exception then?

[Maximum launch velocity?]

• Early space planes using mk1 cockpit tend to overheat to quickly if using a to shallow ascent profile during the rocket phase. But you should try to pilot and stay below that so you would only accidentally do so. Some noobs might but I was never bad at this playing flight sims so I can't judge.
• Using LY-01 and LY-05 landing gear on early rocket planes or even SSTO's will heat up on most ascent paths using juno/wheesley and reliant/swivel engine combinations.
• Accidentally have large gimbal on a engine that is directed at a fuel tank, especially when it's already hot when going fast in the atmosphere.
• Using early rockets without fairings and a high velocity shallow ascent profile can heat up most stayputnik's and therefore destroy the vessel. On low fund/science reward career plays you often want to make efficient low tech rockets so fast high velocity rockets can be such a mission.
• Using early rockets there are no struts, earodynamic drag from control surface deflection and engine gimbal using multiple fuel tank segments will then be able to tumble the rocket at high speed causing RUD due to the loose joints, but that only happens on such rockets.

 

2 hours ago, jnbspace said:

*snip*

However in KSP I have almost never found any of my spacecraft show problems even if I leave the throttle on maximum. Generally by the time I am hitting 1200 ms-1 which is the point at which I would start to see problems I am high enough that I don't see problems. Is there a practical reason (in KSP not the real world) to not just put the throttle to 100% and go for it?

1200m/s and problems? Do you mean heating effect? What do you mean?

As for the last question you asked. The best efficiency during a launch comes from something called a gravity turn. That is a curve the rocket follows from the moment it would want to start pitching which is usually at 100+ m/s after lift off. When past that point you want the rocket to follow prograde until reaching the desired apoapsis with the engines burning continuously. The idea being that you'd need next to no control correction and that gravity itself rotates the rocket as it keeps holding prograde. That involves you learn how your rocket works optimally and that you understand where and how much to pitch or use Mechjeb or GravityTurn mods which are available.

However, as you burn your fuel on the way up there TWR (thrust) increases as you burn fuel, so in order to follow the ascent curve during a gravity turn to orbit you want to lower your throttle at some point. A gravity turn is the best method of a efficient launch. The more aerodynamic your rocket the shallower this curve can become and thus the less Delta-V (fuel) used to get to orbit.

[Landing Legs and Critical Damping]

I'm all for this.

I do want to make a quick comment. KSP wheels can be used, properly, just difficult to setup.
Leaving aside the inner workings of wheel physics in ksp, for some reason the magnitude of effect on the spring and damp settings seem to have little effect from min to max, and therefore you often end up with a set of wheels that are either underdamped or overdamped. In the former you use to few legs, gear or even rover wheels so that even if you use a setting of 5.0 you still get bumped when rolling over terrain. Sometimes the stress is at one location where a landing leg is which then breaks, however you could clip 2 legs at a single spot to have more impact absorption at that area. It is often better to clip 4 legs into another 4 legs then to just 8 way symmetry. It won't look clippy and it is as if you were to use a lander with reinforced landing gear also making them double heavy.

When your overdamped you use to large legs, gear or even rover wheels mind you while trying to keep spring and damp at 1.
Or, you use to many landing legs.

The thing is, you have a particularly sized aircraft, space plane or even rocket that would look good with a particular type of leg, wheel size and would look overly bonky or plastered with added wheels you'd otherwise discard.
User practice is that they want 1 front landing gear and 2 at the back and no more to make the vessel look cool. Often that vessel is simply much heavier then the gear settings can support, or it is intended to drive on Eve where the legs may even fail under stress.
The same vessel could then drive on the Mun if you wanted to with damp and spring set to 1.0, but then it would still have to many legs or gears for it to roll without bounces because the gravity is lower there.

When I require to have a universal vessel like a rover to go to all places I use a specific action group to drop lower gear if required on other worlds and re-adjust the spring <> damp accordingly so I can roll on less wheels when on the Mun.

[Is Squad planning to change campaign gameplay?]

@Pthigrivi I know you optimized the tech tree for early aircraft, but as I was pondering the first node something reminded me I always wanted to say.

Why is it that the "Girder segment" is one of the first parts unlocked?

I know creativity sparks wonders and I'll be rightfully corrected for it's uses. But how does a girder segment function on a early mk1 LF/O rocket, anyone?
Maybe also place the girder segment on another node.

Furthermore, I always wondered why there isn't a stock tech tree plugin whereby Squad makes their own and incorporates a variety of known tech trees that is suited for most players.

[Un-Nerf the Wolfhound. (And the Skiff)]

2 hours ago, KerikBalm said:

Why, because of the better thrust to cross section ratio? By the time you get to a 2nd stage, you're getting nearly vacuum Isp, so the Skiff should be getting equal or better Isp at the start of its burn (as a 2nd stage), and certainly better on average throughout the burn.

Because of the thrust but that isn't the primary reason. It is useful on Eve when your 2nd, 3rd or any subsequent stage using Skiffs is above a certain altitude. But that doesn't make it a best case, just a good option depending on the ascent curve. Some use a very shallow ascent profile and the Skiff is best used only at altitude when the rocket already goes very fast and you'll do most of the orbit insertion higher up in which case a terrier, cheetah, poodle or even rhino is a better choice.

2 hours ago, KerikBalm said:

I would disagree here. The Rhino is an excellent 2nd stage engine, I've even used it as a 1st stage engine coupled with SRBs (although that was pre-vectors, and I think it got nerfed a bit since then)

2nd stage engines that start from 5km up might as well be vacuum optimized. So the only real difference between a 2nd stage engine, and a vacuum/interplanetary engine is the focus on raw power/TWR, and the Rhino's pretty good in that regard. I used it for both purposes. I mainly play 3x rescale now, and I find a mammoth first stage, a rhino 2nd stage works pretty well. Of course I'll also use gargantuan launchers/spaceplanes to take a Rhino to orbit and use it as an ejection stage engine for large interplanetary missions, but I think the Rhino definitely has a role as a 2nd stage engine

Some pics of craft that worked with the Rhino firing from sea level to orbit, stock KSP size:

Well, your showcasing a shuttle, which is 2 stages, in a way it's a tsto discarding the srb's. While I wasn't clear my comment basis is referenced based on a multistage rocket design where each dedicated stage is used and where a dedicated engine is used in the upper atmosphere potentially leaving a rhino in orbit if you so desire to go elsewhere. Some multistage rocket have their 3rd stage that I put Skiff's on prior, but I could already fire them by dropping 1st stage boosters to free up their thrust vector. Also, the difference between 5km and 10km does make a big difference even although 5km has the thickest air. This does involve a ISP difference of ~10 even ~15 on some engines, mind you it is a 50ISP difference for the aerospike.
Also know that ISP scales with thrust, so the thrust at sea level is lower. So a better engine means more thrust per mass over the entire timespan to orbit, so it's a tiny more thrust to battle gravity losses next to having a little more Delta-V. In the end a more specific engine combination always proves to be better. But since the game is gamey a dedicated Kerbin launch rocket doesn't require sophisticated stages to get most things into orbit to begin with, so on Kerbin I'm usually not that nitpicking, as long as the engine performs efficiently at the places I want to go. For that matter I enjoyed the old Skiff much on some Eve ascent vessels, but that is it.

Furthermore, if it is a 2 stage design and the upper stage (shuttle) is meant to go elsewhere or do stuff in orbit and uses a Rhino to assist of the launchpad, then I would do that also in which case it's useful. Either way, having use for a Rhino as long as it ends up in orbit to do stuff there is a viable reason to put one on your rocket, even if it is less efficient then any other option. For that matter I got a few TSTO's using a Rhino.

[Un-Nerf the Wolfhound. (And the Skiff)]

7 minutes ago, KerikBalm said:

Then you should have been around when the aerospikes and poodles got 390 Isp.... When the soup-o-sphere meant that you needed 4,500 m/s (give or take 50 m/s) to get to orbit. Then aero-changes dropped that number to about 3200, and they thus nerfed engine Isp across the board. The result was that smaller rockets could get to orbit, but bigger rockets in orbit were needed to go places.

Yes.

8 minutes ago, KerikBalm said:

And yes, the vector has some OP qualities that basically disappear once in space. Once in space, thrust to cross section ratio is pretty irrelevant (but its very relevant for aerodynamics inside atmospheres)... so I don't mind it sooo much, since this is a space game and it only really matters for Kerbin/Eve/Laythe... and for Kerbin and Laythe, airbreathing engines are so much better, that its hard to consider any LFO rocket overpowered for its atmospheric qualities in an O2 containing atmosphere.

So in the end, the vector is the king of 1st stage eve ascent engines... which is a niche I'm OK with. I'm also ok with its other properties that make it a good shuttle engine, but I'd rather see 1.875 or 2.5m SRBs and weaker vectors. Also, surface attach might as well be present for any engine, as it saves part count (otherwise, you can surface attach a nosecone, and then stick an engine below its node).

Considering this is a space game, I'm most concerned with vacuum performance, and the wolfhound's was way too good, and rightfully nerfed.

I think the Skiff was maybe nerfed to hard... its TWR is lackluster, and so is its vacuum Isp. Worse TWR and Isp than the Rhino. Worse TWR (19 vs 22) than the Skipper for only 10 more Isp. Barely better TWR (19.1 vs 18.3) than the aerospike for 10 less Isp. It should get a thrust increase... but its hard to make it not redundant with the skipper. The skipper has better atmo Isp and the skiff better vacuum Isp, so I guess maybe buff the thrust of both of them (the skipper is pretter lackluster too, and since its better suited as a 1st stage engine/1st stage with some side booster assist, it could always use more thrust).. with the skipper getting proportionately a bit more of a buff...

I'd bring the skiff up to the TWR of the current KR-2L (its still got a lower Isp), and then bring the skipper TWR to halfway between the KR-2L and the mainsail. Masses would stay the same, TWR buffer by increasing thrust.

I almost never use a Vector in vacuum unless I bring it with me to where I need to be, like a eve lander that has their engine vector free from blockage.

I have rightfully used the Skiff on upper stages, even some of my Eve lifters used them because of their relatively good TWR before they got nerfed. The Skiff having a TWR of 19.1 as it is now used to be less heavy so I could use plenty to get the required thrust, now when I do use them I cut the Delta-V budget on the way up so much that I could use many alternative engines.
The skipper is a very good example you gave there, adding to that the Skipper has a Atmospheric ISP of 280 vs 265 on the Skiff. So by all means, skipper engines can be throttled sooner on the ascent curve compared to Skiffs while having more thrust per mass. So what is the Skiff good for I wonder if it's intended application is tackled by a pre v0.90 stock engine?

Because of what I said the buffed skiff engine is kind of out line because the Skiff is a upper stage engine. In theory, any rocket using upper stage skipper engines will do better. I wouldn't compare to a Rhino directly since it's primarily a vacuum or interplanetary stage engine only while the Skiff or Skipper can be upper stage engines. As for the aerospike, it's still a atmospheric/vacuum optimized engine that has the best ISP range throughout a flight profile. To my humble opinion, the aerospike is a case in and of itself. On eve it is a winner and proper assist engine, especially useful if you light aerospikes within eve's atmosphere all the way to orbit without staging them. This allows to make proper use of the engine stats as a aerospike is put to best use if operated throughout the ascent entirely. When not on Eve aerospikes nearly never win the race, albeit on space planes having them. Because of a aerospike lower thrust to cross section and having no gimbal you need quite a few + extra control surfaces or reaction mass/wheels that would add dry mass to take with you. On space planes using wings you need less thrust and thus less aerospike engines. In that case the LF/O is put to best use when using a aerospike. However, who would want to build a aerospike space plane when you got a better alternative, jet engines. In case of another aerospike application, it should make the furthest reaching rocket space plane capable on a atmospheric world, which is handy if you want to hop science equipment on eve using ISRU.

 

[Hmmm... What's this?]

You people are staring wrong, what did I see there, a Monolith growing out the top (whatever top and bottom is/)

[Healthy autostrut use]

5 hours ago, RocketSquid said:

@Aeroboi so I should use grandparent if it’s supposed to dock with something, heaviest otherwise, and use rigid attachment only when I want to avoid bending at all costs?

In all cases the answer is yes, however, if a vessel and space station aren't very complex in terms of part count then docking them shouldn't be a problem in most cases. That's why I recommended to quicksave and if necessary change autostruts before docking.

[Healthy autostrut use]

@RocketSquid Autostruts is always better then no autostruts, so it's always a good idea to use them. The larger the size fuel tanks is like (3.75m) or (mk3) have less rigid attachment connections, so the higher you go beyond 1.25m the more necessary autostruts may become. In case you want to avoid them when not willing to you should use short Mk1 and Mk2 sized fuselages and a short width wingspan with 1 or 2 engines, that could do without autostruts always with minor part rigidity under stress. So beyond that I'd use autostruts always. Below that I'd discard using them. Remember that the amount of attachments nodes, further surface attachments like other fuel tanks and the total width, height and length of the vessel determine the joint strength. So 8 small 1.25m fuel tanks are more flexing then 2 big ones.  Beyond that it is the engine thrust location (usually at the bottom) and aerodynamic stress that further request necessary autostruts use.
Also, the distance from one part connection to another further degrades the rigidity or stiffness. So a part autostrutted to a part that is furthest away will become less potent then a location closer on the vessel.

Rigid attachment is what it says it does. It makes a connection rigid, like glass is. Glass breaks normally when dropped, the same goes with rigid attachment. Part stresses remain the same so if the particular connection is stressed like by impact or through aerodynamic stress on wings then the part is likely to break.
Due to rockets and planes undertaking a lot of stress it is better not to use rigid attachment only if you got a particular good reason.

Out of my mind I would only use rigid attachment  for.

• Certain custom bearings to hold parts in exact places (stock propellers or mechanisms)
• Large ground construction bases using I-Beams and girders to stop flexing
• Sometimes on longer rockets it can be good to stop drag or engine thrust vibrations causing bending and swaying. Imagine a very long rocket that is thin it can make it super stiff so that the drag from the bottom fins or force of the engine gimbal doesn't alter the structure. Just don't try to land that rocket at the bottom hard as rigid attachment will make part attachments brittle and break off more easily.
• On wings. While most people don't it can be used on small to medium large planes when using multiple segmented wing pieces, usually on wide wing aircraft. Don't use it on the wing piece directly attached to the fuel tank as it get's the greatest stress, which is what most people do and then discard the option as wings snap off. The first wing piece is where bending needs to be as it holds the wing so never use rigid attachment there. On the outer wing segments it can make sure wing tips don't overly bend. Because the first segment bends the other segment that is set to rigid attachment doesn't snap off as the first segment absorbs the stress first keeping the snap off point at bay.

For autostruts you have Grandparent which makes that part connected to the part it is node or surface attached to. Heaviest and root part is obvious, however, if using large part count vessels make sure that if you dock to another vessel that has a heavier part the autostrut will connect to there or any of the root parts on any both vessels will change to any of both. Sometimes this will give explosions or problems so quicksave first and if so make sure to set all heaviest parts to any other as you can change autostruts in flight.

Because of this the grandparent is the safest option, if you do a lot of docking using large part count vessels make sure your vessels use mostly this setting. Usually the problem described isn't very common when using less complex vessels.

Grandparent

As described it struts the part to the part it is attached to. In terms of strategy you best use grandparent autostrut on every part within the core stack. A stack is a single long fuselage, in terms of the core stock it means the one in the middle that has the cockpit or command pod.
This stiffens the vessel on every part connection making sure it doesn't bend.

Also use grandparent part on the first part attached radially like a decoupler and also the fuel tank attached to it. The reason for this is that the connection that holds up a entire stack that is radially attached is located at the fuel tank to which it is attached first.
If you have a very long rocket it is best to attach the decoupler and fuel tank (or fuel tank directly) in the middle of the length. This makes neither the top or bottom will flex when fully building the stack further.
Using grandparent on these parts makes sure the Center of Mass of the radial fuel stack is bolted in the center.

I you use either mirror or radial symmetry using grandparent on the lower or top parts will grandparent strut the parts together so i.e. a 6 radial booster setup will have all 6 i.e. nose cones attach to each other so stress will not bend their relative alignments.

Heaviest Part

Using heaviest part seems usually the strongest for me. The reason being is that the heaviest part is usually the largest fuel tank, that fuel tank is usually at the middle. Using heaviest part autostrut means most parts are closer to the heavier part then root or grandparent, and while grandparent won't solve all problems heaviest will universally make the strongest vessel if all people would auto use this setting on every part. The reason why it works best is because the closer the autostrut connection is, the stronger that connection holds up, the same goes for using the strut part connector. Dragging a heavy part further out will bend more under stress when using any autostrut or strut part connector.

In practice "Heaviest part" it is best used on parts in the radial stacks like boosters and extra fuel stacks for larger space planes. This involves most of the fuel tanks, cones and engines other then the one directly attached to the core stack which should be set to grandparent.
Using it on the bottom will make sure the bottom parts of radial stacks which are usually fuel tanks and engines stay in symmetry to the center stack as this will stop bending them under stress.

Root Part

Root part is best used on parts that are closest to it that are not in the center stack at which the root part is located other then those directly attached to it. In that case using root is similar to using grandparent, which is the reason why  
On a regular rocket root part is usually a command pod on top. Using root on the top cones on any radial stacks or any fuel tank below there will stiffen those parts in aligment with the root and center stack.

Also, using a very small middle sections like on a 0.625 or 1.25m probe core that could be in the center of a stratolauncher type aircraft then the very large fuselages on the side would be very flexing unless every part of those fuel tanks were strutted to root instead of heaviest.

In other words, if the root part is not a very heavy part that takes in a lot of stress from the heavier parts then it is best to set root autostrut on the heavier parts.
In case of a space plane, the heaviest part is usually a fuel tank in the middle. To that fuel tank are wings, engines and landing gear attached that take in impact force from landing. When radial outer parts selected to heaviest the wing, landing and weight stresses of those outer parts will be strengthened more.

In relation to the above, that center fuel tank could be the root part, but usually it isn't. Imagine that you have any vessel, rover, space plane, aircraft or rocket to which most of those stresses are located at or near the root part, like in the example of a stratolauncher vessel. In that case strut every part to root that you would normally strut to heaviest.

 

[Are radiator panels useful for anything other than mining equipment?]

26 minutes ago, Daniel Prates said:

And besides that would be a little gamey, dont you think? I mean, in RL the radiators couldt be used like that. As a matter of fact I read above people talking about using radiators during reentry..... in any serious scenario they would simply be OBLITERATED WITH EXTREME PREJUDICE if used like that.

 

My humble opinion: radiators work better - thay is to say, they make more sense - in modded games. Near Futute Elecrtical for instance. In vanilla games they really only make sense with converters, and very low in Kerbol's orbit. I mean, waaaay too low. If you ask me, we should need them even when coasting to the Mün.

Yes, thin metal plates and pipes are not very rigid. Often a aluminum or copper alloy is used which is also not strong to begin with, and, not that heat resistant either, so 2500K heat resistant makes no sense. Because of this the radiators are very light, so why does it have these attributes?

Anyway, the suggestion I made was gamey intended. Logical or not it is fun and people could try.