Building a long range miner rover carrying SSTO - tips wanted regarding efficiency

[mystik]

58 minutes ago, Palaceviking said:

Maybe you should try avoiding using the rapiers in rocket mode as much as possible because they're very hungry when you do! once your above 15/20k then the isp of the poodle probably surpasses the rapier and could be used more for the apoapsis climb, also don't use tthe rapiers to circularize unless you absolutely have to.

300 tonnes! close to my record for am ssto

I know what you mean, I could replace a few of the engines with Whips, but the problem is that they will only be useful on Kerbin. For the rest of the flight they are just useless weight. I want to have stuff that I can use at all times everywhere. My flight is very forced when I go for orbit. I use air mode up to 25000m then switch to rocket mode and point it to 45 degrees to get as high as possible and have to deal with less atmosphere as possible. I know it's not best but I found it more doable to jump to 50000m as fast as possible and then gain orbital speed. I pretty much use rapiers to circularize quick then switch engines.

The thing I started with had 486.36t (check the link) so I've lost almost half the mass on the way. The thing surely flew better then than it does now, but it was too big and heavy for what I needed, don't think it could have landed on other planets very well.

Speaking of landing, I have added one dart engine mounted under the front wheels and hidden inside the cargo to help position the front slowly after landing without being affected by drag. I wonder if this will work as I have not yet tested it like that, I know you come in with the back and slowly maneuver until you slow down enough to retro burn close to the ground, cut the power, then flip, at which point you use a control engine to keep the nose from slamming the dirt too fast, does anybody have any tips on landing these things?

Edited January 6, 2017 by mystik

[Palaceviking]

Dart sounds like a good idea, also ssto's just don't fly well in atmosphere generally so that's a trade off.

Also for yours you might want to try a non-standard ascent profile of using the aerodynamics after 25k (if you can take the heat!) of jumping to 35 k then glide up on poodles, will save fuel i think even with the drag, then go for a smoother apoapsis and longer circularisation burn?

Not claiming to be an expert in these things but I had to use this kind of profile with my super heavy ssto's on nukes before. 

[Signo]

Do not forget you have wheels, you can go for a flatter landing where the terrain allows you, like on Minmus flats. Do not forget you are technically landing backwards, so if you have a tricycle configuration at take off, while landing in vacuum you will have a taildragger. You need to tweak the gears before landing to adjust the steering direction and brake balance or you might experience a sudden tailspin.

Do not be too afraid of "bouncing", engines and wings are pretty tough. "Rigid attachment" and "Autostrut" are your friends.

I suggest you to disable gimbal, you do not want your CoT going around while landing a "longship" and you should have plenty of torque to maneuver as you please. 

I recently added a LY-10 wheel on the angled plate of the engine mount to avoid issues at take off on vacuum bodies.

 

[mystik]

Hi,

 

I finally added the link to the craft in the first post. I also add the link here http://kerbalx.com/mystik/Thoth-III

 

I am happy with the design, however I have a major issue. The Delta V is not enough. I can get to space with about 1200m/s left but this is not enough for getting to the Mun or Minmus to land and refuel as I run out fuel. The plan is to start with full fuel but less oxidizer as I end up with too much oxidizer and too little fuel and I just end up carrying the stuff which I can't use.

 

Currently I can get 10.9 km/s. To be reliable I need about 15km/s. I am stuck. I don't want to use Nerv engines since that means that I have to use liquid fuel and crawl anywhere. I use the Poodles and I can move about with them quite easily. I feel frustrated. I tried to reduce the weight so much and optimize everything but it's just not enough. If anybody has any ideas, I am listening, willing to add more weight, but not wanting to add too much mass overall.

 

Be careful when trying to fly this thing. It is very FRAGILE. The wings will clip off if you push the maneuvers over 500m/s too hard. This is to save weight and keep things useful. I could add a tank of liquid fuel to get me to space and have lots of total fuel left, but that means that I waste the tank once in space since I won't use it anymore. I aim for efficiency, not carrying useless stuff in space.

 

I need about 15km/s to reach places. I could do it with ion engines, but that's ridiculous and they are not refuelable. Feel free to criticize the poor design because I'm sure I could have done something better.

 

PS: Don't bother operating the rover, it's there to simulate the weight, but getting it on and off implies the use of the landing gear of the plane and the landing gears of the rover that needs to be used in a certain sequence. I will provide additional details how to easily operate the rover loading and unloading once I can get this thing to work. I don't care for the rover right now. Also, I know that the model has a landing gear wrongly alligned on the right engine, you can remove it for tests, it's something that appears when I try to duplicate the engines, you can ignore that (reuploaded fixed model, screenshots not updated).

 

 

Thanks,

M.

Edited January 9, 2017 by mystik

[AeroGav]

@mystik

What kind of ISRU SSTO are you trying to build again?

I've made a couple of low TWR ones, that can land on Laythe and Duna (where there's atmosphere) and also on low gravity moons.  My designs have lots of wings and aerodynamic surfaces (so they can land on Laythe and Duna like an airplane) and fewer jet engines.  By achieving a high lift:drag ratio, you can get away with fewer jet engines and less oxidizer / more nukes, because you won't need such a high TWR to avoid gravity losses.  

Of course, when going somewhere where there's no atmo,  all these wings etc. won't help one bit.   That's the opposite of what i'm used to doing, so i can't be of much help.

I suspect what you are trying to  do is extremely hard.     You can have high delta V, by keeping the number of engines to a minimum making a greater proportion of the ship's mass fuel.   Or you can have high TWR, but this will hurt DV.  

To get both requires minimising everything that is not engines or fuel from your craft, including sacrificing aerodynamic performance.  Also, if you look at this dV map, at the moment your craft requires at least 4670dV to reach minmus from the surface of Kerbin (the first hop).  However, you only need half that much for the planet hops.    So you could decouple wings, jet engines and drop tanks to get off Kerbin, and be SSTO from then on out.

Another idea, you could put the NERVs (and perhaps, most of the wings, since you'll likely want to mount them on your CoM) on docking adapters.    When visiting somewhere like Tylo, you could undock these and leave them in orbit, leading to a substantial mass reduction (better twr for landing,  better dv in chemical mode for the return to orbit).

Alternatively, just forget making your SSTO able to land on high grav airless bodies.    It would still be highly useful as a support tender for operations in almost any part of the kerbin system.    Eve mission ?  It can IRSU gilly and refuel the Eve ship.   Tylo mission? IRSU Laythe, Pol or Bop.

If you really need to visit the surface of these bodies, would it be better to put a small, chemically fuelled lander in the cargo bay.   A low TWR mining SSTO will have >5000dv and there's bound to be somewhere it can land to refuel at within range !

 

Midguard

486T Gross wt

282T Fuel (58% fuel  fraction)

83T Engine mass (17%)

Other stuff 25%

Jet engines are 10.9% of its mass (5 whiplash , 22 rapier)

Nuke engines are 6.1% of its mass

 

Nostromo 

(a mining ship i built last year, if i built this now, i'd angle the wings with incidence to improve aerodynamic efficiency)

82 Ton Gross wt

41.5T fuel (50% FF)

12T Engine Mass (14.6%)

Other stuff (35.4%  - i suspect main reason is that mining hardware is bigger proportion of smaller ship like this)

Jet engine mass 7.3%

Nuke engine mass 7.3% of total

 

 

[mystik]

51 minutes ago, AeroGav said:

@mystik

What kind of ISRU SSTO are you trying to build again?

Something medium weight, able to travel to all places minus Eve and Tylo, that is able to refuel on site.

[KerikBalm]

On 12/28/2016 at 11:13 PM, mystik said:

 

 

I'm looking to replace the end with a cargo loading bay for rovers. Should I attach rovers with a docking port? Is it possible to attach a rover using two docking ports at the same time (one forward and one underneath)?

Prior to 1.1, a 2nd docking port was required to prevent the rover from clipping through the craft upon connection (and then when you disconnect, the clipping parts registered collisions, and explosions ensued)

Here's an example of such clipping:

Two docking ports required very careful alignment:

In that case, the magnetism alone was enough to keep the rover from falling through... or that was somehow counted as a 2nd connection.

After 1.1 and wheel auto strutting, this is (mostly) no longer an issue. The instant the docking connection is formed, the rover wheels will auto strut to the parent craft (not sure if its the parent part, or the heaviest part). One can now simply drive rovers on and off the ramp, and a single docking connection is enough to keep them secure in their bay (I like to think of this as abstracting the process of securing the cargo with straps in the cargo bay).

For my mk3 bay rovers, I have a standard cargobay of a mk3 cargobay, and a node mounted dokcing port - easy to reproduce. I make all my rovers designed to be able to dock with that node, and thus I can make multiple rovers that can be carried by the same cargobay *and* dock with each other to form a surface base.

However, a claw is even easier, and it seems that the bugs with them are gone.

 

A few things to consider:

#1) "Range" is pretty meaningless in space travel. A ship capable of landing on Eeloo and returning may not be able to get to Moho and return, despite Moho being closer.

The important criteria are dV and TWR, and different combinations are required for each destination.

#2) Space travel is not like earth travel. Even on Earth, we don't use one vehicle to go anywhere. Sure a Helicopter with floats may seem like it can visit all of Earth... but flying VTOL subs are out of our reach, and high altitude locations like Everest are also out of reach. Its even worse in space, (In reality, and to a lesser extent KSP for that matter.

In the stock solar system, those jet engines are *useless* everywhere except Kerbin and Laythe. When trying to single stage to locations like tylo, You'll be able to cross the solar system, but then be limited to where you can land on the surface because of ore. Eve will be forever off limits. You can't make a single craft that can go anywhere and do anything, so what are you actually trying to make? You can make one craft that can visit multiple different bodies, and be fully reusable - so what bodies are on your list of desired destinations for this craft? Do you want to be able to set your craft down anywhere on said bodies, or is it acceptable to be limited to high ore areas?

#3) related to the above point: SSTO != spaceplane. You could make a pure rocket SSTO, and if you can get it to land on minmus and refuel, you're likely to have an SSTO better suited to any destination except Laythe relative to your spaceplane SSTO.

This probably meets your criteria:

or the miner in the background here:

(with its 2.5>1.25m adapter docked to give it extra fuel, and aerodynamics for kerbin ascent)

#4) You can do fully reusable without doing single stage.

SSTO doesn't mean single stage the whole way, just To Orbit.

I make use of many stages in my reusable SSTO designs.

This is a SSTO, carrying a mining rover:

Spoiler

 

It gets to orbit, and needs to be refueled to go beyond LKO, its still a SSTO.

All this got to orbit using a single stage, recoverable, launch vehicles: 

(granted it involved 4 launches: 1 for the KR-2L booster, 1 for the center section, 1 for the faux "centrifuge", and of course the space plane docked to the left of the image launched itself).

Its an SSTO to laythe and back... at least single stage to kerbin orbit, then fully recoverable to laythe and back. The KR-2L stage ejects the ship from the system, and aerobrakes back to LKO/mun for refueling and re-use. The rest of the ship inserts into laythe orbit and acts as an orbit fuel depot for the SSTO (single stage to and from laythe orbit) lander. The whole thing can come back to LKO and reassemble.

You can even do reuable to the surface of eve and back, if you're willing to split your ship up.

What is the obsession with not splitting ships up, what is wrong with making use of "apollo style"?

[mystik]

How do you @user on this forum?

 

Anyways, I wanted a universal ship to get me places, and since some planets have atmosphere wings are required to reduce delta v and make it easy to fly around.

 

I am sticking with this design. It's compact and it works. It just needs better fuel management.

[Spricigo]

2 hours ago, mystik said:

How do you @user on this forum?

 

Just type something like @spricigo and a tooltip with the name spricigo will show up, click on the desired name and the magic happens: @Spricigo

[AeroGav]

1 hour ago, mystik said:

 

I am sticking with this design. It's compact and it works. It just needs better fuel management.

I just downloaded your ship.   It is very different to anything i would build (no nukes, tiny wings, huge twr) so it's fun to be in something different but also, i have to thank you for creating the most exciting takeoffs i ever experienced.      You tuned that thing to perfection - stall speed of 160 m/s and it misses the water by barely 10m   

I'm thinking of trying a version based on a pair of Rhinos, a pair of nukes  some droppable boosters, and an as-yet undetermined amount of panthers and rapiers...   brb

[mystik]

3 hours ago, AeroGav said:

I just downloaded your ship.   It is very different to anything i would build (no nukes, tiny wings, huge twr) so it's fun to be in something different but also, i have to thank you for creating the most exciting takeoffs i ever experienced.      You tuned that thing to perfection - stall speed of 160 m/s and it misses the water by barely 10m   

I'm thinking of trying a version based on a pair of Rhinos, a pair of nukes  some droppable boosters, and an as-yet undetermined amount of panthers and rapiers...   brb

It's built on the limit. Everything kept to the bare minimum. Have you seen the size of the ore tank? Nothing is added extra more than needed. I had a version with 12 rapiers. It required to go to 10000, go into a dive, reach 500 m/s, then pull up slowly to gain altitude. It worked. But I lost many wings doing that. And wasted a lot of fuel, so it was better to add extra engines.

It does give you the "Oh man, this is going to crash" feeling. If you pull hard at the end of the runway it will fly. It is light for its size but this makes it fragile.

 

I have an idea. What if I stick 2 orange tanks and clip them inside the fuselage. It's cheating but it adds no drag, no extra size, only weight. Might just give me that extra dv to reach the moon or minmus.

 

I have a user manual on how to fly it and how to operate the rover. I will post it once the dv stuff is sorted. Sorry for the whole mess.

I will try to improve it and come back with updates. Thanks for trying it out. It's great to have some feedback.

Edited January 10, 2017 by mystik

[AeroGav]

27 minutes ago, mystik said:

 

I have an idea. What if I stick 2 orange tanks and clip them inside the fuselage. It's cheating but it adds no drag, no extra size, only weight. Might just give me that extra dv to reach the moon or minmus.

Clipping doesn't prevent drag unless you're inside a cargo bay, and only then if you fall within the dimensions of the bay AND have the part (or one of it's parent parts) attaching via one of the cargo bay's cargo attach nodes.

That said, 2.5m tanks are the most efficient in terms of drag per unit of fuel of all the tanks.

In terms of my mod, of your ship, it's got issues

https://kerbalx.com/AeroGav/Thoth-IV

Fanboy in me loves to see 3 different colours of afterburner flame and we've only just took off.  The whiplashes are boosters, as are the outboard wing segments between them and the panthers. 

It also has two nervs and of course, two rhinos.    Got to 26km mach 4, activated rhinos, but ran out of LF. We had 4k oxidizer left over.  

At this point i'm tempted to "cheat" and just use configurable containers mod to change the ratios of fuel stored in the tanks to match what the craft uses. Otherwise it's a huge redesign.

The concept might have merit - use the highest TWR and Vacuum ISP chemical engines as basis for Tylo landings, but keep a pair of nervs for interplanetary transfer burns.       Also, if you use something else to get you through the sound barrier and get the RAPIERs singing, you don't need very many of them at all.  Either booster engines or a burst from the Rhino.   I figure kerbin to minimus is the hardest step, hence the booster whiplashes that get discarded.

The insurmountable problem for me, is how to you take off from Tylo, vertically, like a rocket, with all the deadweight of an irsu ssto spaceplane, and still have enough delta V to reach another body?

Edited January 10, 2017 by AeroGav

[mystik]

1 hour ago, AeroGav said:

Clipping doesn't prevent drag unless you're inside a cargo bay, and only then if you fall within the dimensions of the bay AND have the part (or one of it's parent parts) attaching via one of the cargo bay's cargo attach nodes.

That said, 2.5m tanks are the most efficient in terms of drag per unit of fuel of all the tanks.

In terms of my mod, of your ship, it's got issues

https://kerbalx.com/AeroGav/Thoth-IV

Fanboy in me loves to see 3 different colours of afterburner flame and we've only just took off.  The whiplashes are boosters, as are the outboard wing segments between them and the panthers. 

It also has two nervs and of course, two rhinos.    Got to 26km mach 4, activated rhinos, but ran out of LF. We had 4k oxidizer left over.  

At this point i'm tempted to "cheat" and just use configurable containers mod to change the ratios of fuel stored in the tanks to match what the craft uses. Otherwise it's a huge redesign.

The concept might have merit - use the highest TWR and Vacuum ISP chemical engines as basis for Tylo landings, but keep a pair of nervs for interplanetary transfer burns.       Also, if you use something else to get you through the sound barrier and get the RAPIERs singing, you don't need very many of them at all.  Either booster engines or a burst from the Rhino.   I figure kerbin to minimus is the hardest step, hence the booster whiplashes that get discarded.

The insurmountable problem for me, is how to you take off from Tylo, vertically, like a rocket, with all the deadweight of an irsu ssto spaceplane, and still have enough delta V to reach another body?

I think it's time to go back to the drawing board. I managed to do some brute force using high twr engines, but I still end up with low dv in orbit.

Maybe I need to go bigger. Add another set of tanks on the sides and more engines.I'm thinking that would help. That would require a redesign of the wings as well, to improve lift, but would add more weight.

It's time to go full delta wing.

[mystik]

I will add this post from a different thread to use as reference, because the long trips to and from work help with ideas, which I like to keep for when I have the time to implement the plans.

 

1. I believe it is capable of landing and taking off from Tylo as it is now. It does require to visit some other moon first to refuel so a direct mission isn't possible. In fact, none of the missions can be direct, all must be done by "planet hopping". I launch it to orbit, then refuel it via another SSTO that carries lots of fuel, then continue the journey, not knowing it this will work for sure unless I try landing it there.

2. I think it is time to go 3 ways and experiment to see which is better:

a. Make it 4 horizontal tanks and engine ratio it currently has. Because each tank has to pull less central weight, this will increase the dv remaining, but as long as I keep it aerodynamic to not create too much drag. This model isn't really that great because it makes the ship huge, clunky and heavy. Because I intend to land on planets with low gravity this will become a problem because I won't be able to control it very well on landings. The Spike engine under the ship won't be enough if I double the weight. This has low chances of success.

b. Make it 3 tanks, making it look more like a prism. This requires switching to a delta wing to be able to carry the thing as the current layout will not allow for the thing to fly anymore. It is already on the limit and the wings would snap off the moment you try to make any maneuvers. Assuming you can actually take off. This has a moderate chance of success.

c. Create an orbital tug ship that launches separately and functions as a rocket instead of a space plane. Switch out the front claw with a docking port. Create something like a sky crane that tugs the space plane to preserve fuel on the main ship and use that to get places and use the ship itself to land and refuel and take fuel back to orbit to the tug ship to refuel. This will also allow me to add a backup propulsion system based on ION engines for emergency cases where I get stranded in space. I can add 30 engines and that should return it back in case it gets stranded. Since the tug ship does not need to land, it can carry ridiculous amounts of fuel and can be assembled in orbit via multiple launches. I can even create a dedicated part of it to decouple into a giant ISRU for low gravity objects to carry the crazy fuel needed to orbit. This has the highest chance of success but it will create a logistical nightmare for the non experienced user that has issues with docking. There will be a lot of docking. A LOT. More time will be spent preparing for missions than the actual missions. Not sure if that is very appealing to the normal user, but that means you can visit most of the places, except Eve. For that, I have to figure things out, maybe make a SSTO rocket that I can deliver there in advance then travel with the space plane and transfer the crew. Either way, it will enable people to fly everywhere, using 3 ships in total, one of which can be permanently left in Eve orbit for reuse.

 

Sorry for using this thread as a scratchpad, hopefully this does not break the forum rules, I constantly come back to this thread to see what I can research or follow up on ideas.

Edited January 11, 2017 by mystik

[mystik]

Big update on the design. I have reduced the weight even more and now the thing has 3200m/s in rocket mode. 10.8km/s in jet mode fully loaded. 12.3km/s with optimal fuel load. I need to test it a bit. I will upload the model soon. Flying it became much easier.

 

[mystik]

After some testing and designing, I have solved the problem, at least so I think. Presenting the 3 part expedition fleet.

1. Bee: Rover for advanced roving needs, able to flip itself back if needed, fully autonomous, emergency docking capable, advanced recovery vehicle;

2. Thoth: SSTO for all your expedition needs (except Tylo and Eve), able to land on Tylo, take off, but not escape it's orbit on it's own, but there's a solution;

3. Trident: Orbital and interplanetary tug ship, able to refuel on a moon and rescue the Thoth from low orbits, suited for non-atmospheric planets only.

 

All tested separately, no parts are dropped, assembles in orbit. Does not require additional rocket assistance. Fully automated and fully refuelable.

 

Tylo plan: Thoth lands, does science, refuels, goes to low orbit, then is docked by Trident who is able to pull it to safety in orbit to one of the low gravity moons for refueling.

 

http://imgur.com/a/rn28R

 

I have some math done, but I can tell you that the only places it cannot do are Kerbol (not enough dv to reach), Jool (no surface to land anyways) and Eve (not enough dv for reaching orbit).

Edited January 16, 2017 by mystik

[mystik]

Hi guys, sorry for the lack of updates, but the development of this SSTO has ended. Reason: I could not get enough DV out of the thing to make it viable for long distances. Also, @Korsakovski has made the Kraken E4, which has so much DV left that it puts my design to shame. If anybody is interested in any of the designs listed here, I can post some links. However, you can consider them obsolete. Still, not all is lost. I have learned important lessons on SSTO building and aerodynamics. I have also come up with a great fully autonomous rover that can science the crap out of biomes, with or without crew, with storage space and two seats. No need for solar panels, fully able to return to horizontal if flipped, no matter the gravity, even able to dock with a ship in space on it's own power. For mining assistance, it can serve as an additional power source to help when not in use. It can dock while landed in all gravity conditions, since it can lift itself to various heights, using retractable landing gears under the chassis.

 

I will be using the rover as it is an awesome rover that can be attached to the front of Kraken E4, and can withstand the heat of atmospheric flight even if it adds some drag. The Tug can also be shared, but it is not needed anymore. Seems that my building skills are not as awesome.

 

Seriously, if you are looking for an interplanetary SSTO go download the E4 from here https://kerbalx.com/Korsakovski/Kraken-E4. It gets the job done. I have been tweaking it a bit to add science, and if the author approves, I will release it to the public as well once I am done with it.

Edited February 9, 2017 by mystik

[George van Doorn]

So you want a long range miner huh? How 'bout this one?

You wanna add a payload too, you say? Just remove the satellite on top and add whatever you want. I'm pretty sure the TWR and dV wouldn't budge much . You can see it in the other  video parts behaving decently well in all the worlds.

I can give you the craft file if you want.

 

 

Edited February 9, 2017 by George van Doorn
clarifications

[mystik]

38 minutes ago, George van Doorn said:

So you want a long range miner huh? How 'bout this one?

You wanna add a payload too, you say? Just remove the satellite on top and add whatever you want. I'm pretty sure the TWR and dV wouldn't budge much . You can see it in the other  video parts behaving decently well in all the worlds.

I can give you the craft file if you want.

 

 

Sure, I'm always looking for good designs, I'm interested in testing it out to see how it does with the requirements.

[George van Doorn]

4 minutes ago, mystik said:

Sure, I'm always looking for good designs, I'm interested in testing it out to see how it does with the requirements.

https://www.dropbox.com/s/kotf8x3hat3cll4/The Grand Tour.craft?dl=0

Well, you can always add your payload in a fairing on the main core (hopefully you remove something else or it would become too tower-y).

[mystik]

2 hours ago, George van Doorn said:

https://www.dropbox.com/s/kotf8x3hat3cll4/The Grand Tour.craft?dl=0

Well, you can always add your payload in a fairing on the main core (hopefully you remove something else or it would become too tower-y).

I loaded the ship, but it is destroying my framerate, with its 590 parts.

I think you can make it lighter and smaller if you scrap the crew cabins.

Thanks for uploading.

[George van Doorn]

You could

1 minute ago, mystik said:

I loaded the ship, but it is destroying my framerate, with its 590 parts.

I think you can make it lighter and smaller if you scrap the crew cabins.

Thanks for uploading.

You could, but how would da Kerbal Hoard loot them planets, you humie?

Go big, or go home :P.