farmerben
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Posts posted by farmerben
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Temp and thermal efficiency don't change with warp???
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Jinnatonnix, I'm curious, is the mining gear on on LoL3 adequate. Does it rely on fuel cells?
My swan2 plane started with 2 gigantor arrays and 3 RTGs which was plenty to run on Minimus. After the probe drop I had to refill on Laythe and then Bop down 2 RTG's and electric charge was a big problem. I found that some mining gear would run continuously if I left the convertor and drill on with the ore tank empty and let time pass from the the space center.
I might have to run the mission again with a different probe and different electrical gear.
.... Actually my entry had one of the small fuel cells as well. I had it set with the brakes action group and tucked away. Maybe sending an engineer is also a bad idea if he uses electricity faster.
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On the inertia created by electric wheels? No.
On propellant, sure.
If one was required to ignite sepatrons before crossing the canyon it might be interesting.
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Spoiler
I got two Kerbals stuck using two different rovers less than a quarter of the way into each canyon.
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Kerbal scientists believe it is possible to learn more about the Mun by inducing vibrations into the Mun canyons. The idea is to take a rover as fast as possible and as heavy as possible through the canyons. Scientific instruments on board the rover will be compared with other data to detect avalanches and mini-quakes on the Mun. Useful information can only be detected while moving over 30 m/s in contact with the surface. Flying through the canyon or crawling through it will not be helpful.
Also, the only way this mission could get approval from KSP administrators was by offering to use obsolete engines that would soon be scrapped otherwise. The sub-orbital phase of the mission will be performed using only the 0-10 puff monopropellant engine or the RT-5 flea solid fuel booster.
Basic Rules:
Must have a seismic accelerometer, gravioli detector, coms, electricly powered wheels.
The two main canyons are labelled canyon on the biome map. They begin at farside crater running north, and begin at east farside crater running east. Running in the reverse direction is fine. Navigating the entire length of either canyon is a success. Navigating the entire length of both canyons is major success.
Awards:
Fastest time through an entire canyon.
Highest ground impact speed.
Most mass.
Longest jump.
Most epic video.
Most damage sustained and still operational
Zero damage sustained.
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Is it permissible to transfer fuel from the station while rescuing?
Within the parameters of the rules it is possible to give the station a highly elliptical orbit and catch it again in space. Perhaps it should be mandatory to set the station periapsis at 23 km.
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I just want to seethe takeoff from the DeGrasse Sea. TWR is plenty, but are the lifting surfaces going to work?
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This is the probe i used. Ore tanks are much cheaper than RTG's. I could have saved a lot of money.
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45 minutes ago, Mikki said:
Your mini mining rig is very cool, but i wonder how much juice the probecore drains. The most basic probe core runs surely cheaper...
I allways have the feeling that i don`t understand the miningmechanics completely, and i am sure i`m not alone with this.
All the dependencies on location, sunlight, heat dissipation, engineerlevel, amount of engineers, time acceleretion and whatnot make mining a science worth a own subforum, but barely nobody dares to talk about it...Every miningoperation performs unique, i wonder if i missed important changes along the way...
And BTW, where is your converter? Fuel conversion with the small converter was earlier not even worth the hassle, or does it now?
The images I posted are not a real vessel. It's a simple test rig. I tried setting the probe to hibernate, it makes a very tiny difference.
Always use 2 small extendable radiators with small rigs and 2 medium extendable radiators with the large rigs. I haven't tested on Moho, but everywhere else that is sufficient. I never overheat the small converter, I've only read that was a problem years ago. The fixed radiators seem to use much more electricity than the extendable ones. Radiators use a variable amount of electricity based on load.
I like the fact that solar radiation and ore concentrations vary by locations. But that means it is almost impossible to optimize.
Mining by day and resting by night is fine, except for one problem. That is job for Kerbals, not for humans, Give humans a slider in order to achieve continuous operation.
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I noticed the stated electricity consumption rates for some parts do not match. The numbers that appear in the VAB are slightly different than the KSPwiki. I believe the wiki is more accurate, but it is still impossible to use for calculations, especially for drills.
Without an engineer. One RTG can power the small drill and cooling system continuously with a small electricity surplus.
With an engineer. Five RTG's have a small electricity deficit.
Every time I lay out a new mining rig I feel like Goldilocks in the house of the three bears. Always trying something too big or too small...
A solution which would really make mining easier is to have a control slider for each drill, to turn down its rate of power consumption.
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The only mod I used was MechJeb. I have installed, better time warp, vessel mover, and kerbal alarm clock. All the parts were stock.
I had a previous version that almost did the mission, but it approached Laythe with only 400 dV remaining and I couldn't capture without exploding in the atmosphere. After many attempts I gave up. This version has 1000 extra dV, and is better optimized for atmospheric heat. The Kraken killed it several times. But, then I figured out that fast time warp was taking away my autostruts, so I started switching to the space center to let time pass for refueling etc.
Nearly all my airplanes can land on the sea. Only the good ones can take off from the sea at 50 m/s.
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This is a hard mission. It took several tries to pull it off. The probe was not recovered worth 49,980. I guess if I were really paying attention to cost I would not have used RTG's, but I'm just happy to finish.
Spoiler
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6 hours ago, mikegarrison said:
Steam is never just steam. It is always in equilibrium with water. Very hot steam is more "dry" than cool steam, but it always has some liquid water percentage. You have a giant bag, which has tremendous surface area to radiate away heat. The higher you go, the colder it gets outside. How do you keep your steam dry near the bag? You would need a very high bulk temperature and a *lot* of convection to make sure that the steam at the edges doesn't get too "wet".
Great questions! This is the very heart of the problem. We need to know the rate at which heat radiates away. I do not know it.
As you go higher the condensation temperature drops and solar radiation increases. So the colder atmosphere is not a big problem. If the balloons utilize the reflective properties of solar hot water heaters, they will get better with altitude. My experience with 6 mil plastic greenhouses says they can maintain a 15-20 F temperature difference overall While the vaporization temperature is going to drop almost 50 F going up. Convection will fall going up. Solar radiation increases. Ascending requires lowering pressure, thus venting steam or water while going up.
The outer edge of the steam bag would benefit enormously from insulation. My idea is to surround the steam with hot air. The exhaust from a fuel cell is a steamy oxygen depleted air with no heavy CO2, so it would be perfect. Condensation of the outermost balloon only would drip back down to the fuel cell, and if it does not revaporize, then it will fall out. The inner balloons containing steam would be kept super hot and dry if possible.
Using methane to insulate steam would work better much better from the heat perspective, the reverse of an ignition mitigation strategy.
I'm estimating that fuel cells are about 10 kW per ton, plus about 2 kW of "waste heat".
So a 100m diameter sphere of steam would get over 1000 kW of solar power (potentially twice as much with reflectors) , and say 100 kW of total fuel cell heat (that is a very modest gross weight fraction). The surface of the steam bag is 32,000 m2. So at equilibrium the steam bag will dissipate 35 W/m2. From this we can calculate the insulation value for the outer balloon we need. The outer balloon will have a temperature gradient less than 100 degrees, so it's insulation value could need R as high as 3. I'm not sure exactly how much air that is, but the air gaps in 3.5 inch studs count as R=1. So I think that a 3 layer onion of air 1 foot thick has enough insulation such that the inner balloonet would have almost zero condensation.
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Suppose you want 150,000 kg of total lift. A spherical balloon of pure steam 50m in radius has a little more than that. Call it 8000 m^2 of surface area.
Try 6 mil polyethylene. The balloon weighs about 1,600 kg. We are up to about 1% of the old zeppelin dry mass.
Now consider that helium retails for about $1.50/ft3 while methane retails for about $0.015/ft3. Presumably steam can be even cheaper than methane.
So I think we realistically approach 1% of the total cost of previous airships.
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What the video showed was that the old airships of the WWI era had a huge dry mass. Something like 600 g of bulk for every 1m^3 of lifting gas. Actually the cow intestine that held the pure hydrogen was much much lighter than that. Those intestine balloonets were contained inside essentially a (hot?) air balloon made of canvas with metallic paint over an aluminum frame.
It is better to compare it to modern helium blimps. However helium blimps may use thicker materials than what is needed for methane and steam. Helium is never wasted, so these blimps need thick walls, and they compress their own gas supply instead of venting it. Steam may be vented.
I don't have permeability data handy. Isn't it the case that hydrogen and helium leak through almost everything, quantum tunneling is significant. While for steam and methane the leak rate is hundreds or thousands of times less.
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Everybody knows hydrogen is explosive, helium is expensive and rare, hot air is ponderous. But there are other lifting gasses. Steam was used exactly once in 1792 to launch a few animals over Paris, but never again. Methane to the best of my knowledge has never been used as a lifting gas for humans or animals.
It's been a while since I studied this so double check it.
Methane and air cannot ignite if the methane is below 5% or the oxygen is below 12%. Hydrogen is similar, and the mix of CH4 and H2 is similar. Somewhat richer combinations could be safe in some circumstances.
https://en.wikipedia.org/wiki/Flammability_diagram#/media/File:Flammability_diagram_methane.svg
Steam is essentially an inert gas toward methane and hydrogen, below about 3 atm pressure and 1000 C and certain catylists. The ignition point for methane and air under ideal ratios is about 540 degrees C. The temperature to maintain steam falls with altitude (from 100 toward about 70 degrees C). Therefore it is possible to maintain methane above boiling temperature without any risk of accidental ignition.
Now a fuel cell can process hydrocarbons on one side and release hydrogen on one side of a membrane. On the other side of a membrane oxygen from the air is converted to steam, and much heat is released.
A balloon inside a balloon is called a balloonet. Now suppose you had a ballonet that was about 40% methane and hydrogen mixed with 60% steam as an inert gas filler. Surround that with a larger balloon of nearly 100% steam. Surround that with an open balloon of air only the appendix of the balloon is part of the fuel cell so the air in the appendix will be close to 10% oxygen, 10% steam. I would predict it would be virtually impossible to explode the gasses.
Methane and Steam despite being 6 times denser than helium, have half the bouyancy, because what counts is the mass of the air displaced.
Assuming it is possible to keep the steam up. The limiting factor would be slowly converting all the methane to hydrogen and the rate at which hydrogen escapes.
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Starting to use the fuel cell array really opened up a lot of fun with the Dawn engine. The fuel cell array fully powers two ion engines, and it takes hours to burn through a tiny LfOX tank. It's also great because combining oxidizer engines like ant or twitch can vastly increase thrust which covers the greatest weakness of the Dawn. The hybrid is great for suicide burns and landings. And sometimes you need to capture from a hyperbolic orbit, but your maneuver node is in an eclipse.
Solar power is only good enough in the inner solar system. RTG's must have been nerfed since a previous version. It takes 10 RTG's to keep one Dawn engine firing continuously.
As a prior user mentioned, battery power alone can be sufficient for most moon landings. But this leads to a low thrust vehicle that must start it's suicide burn from many kilometers up. The fuel cell array/hybrid is way more powerful.
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I want more rotating parts to attach stuff too. I don't mind installing mods, but I haven't found what I'm looking for.
Stock propellers are really tricky to make and optimize. There are plenty of youtube videos to get an idea on how to make these. But, the ones I made are crappy, and there is just so much detail to work through. I have a mod for rotating docking ports, that even has a step motor part, but these are for robotics not high velocity spinning. I tested airplane parts plus which has lots of gas driven propellers, but I'm looking for a basic electric spinner with some rpms.
Wheels don't work upside down. Why not? One obvious solution to rover flip over is to put wheels on the roof of the rover so it can drive upside down. It doesn't work. Wheels that are not in the most orthodox orientation in the space plane hanger, seem unable to get traction under any circumstances.
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5 minutes ago, sevenperforce said:
Very nice!
I solved the same problem a little differently. After the splashdown and associated mission, I burned off a bunch of my fuel heading back toward land, so that my CoM could be shifted around. I pushed all my LFO to the nose to help me get the front canards underwater, then went as far down (and as fast) as my RAPIERs would push me. Then, I then transferred some of the LFO back to the back so that it would help me kick the nose up, and I did a "breaching whale" jump with a Closed-Cycle burst from the RAPIERs. Got me going high and fast enough to stay in the air, and it was a quick trip back to land.
Nice. I've done the dolphin jump before too. The thing is it requires TWR > 1 on oxidizing engines. Which means a sea plane that doesn't rely on it can carry much more fuel.
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I have not had this problem. Is it possible you were out of electrical power, and the reaction wheels where not working at all?
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This mission is proving harder than expected. Sea planes to orbit I'm fairly good at. But, I keep having to push for more dV and more payload which means most of my designs can't cut it. I think I need to get rid of mK2 parts and get the probe in a 1.25m payload bay if I can.
I discovered a new trick for taking off sea planes: Truly massive flaps to move the center of lift forward of the center of gravity. I'm using the big spaceplane tail fin as a front wing. With the authority limiter over 100 it would just back flip if the flaps stayed on, but for a few seconds to lift out of the water it is perfect.
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Landing difficulty is purely a function of acceleration caused by that body. I have run out of fuel to get home at Moho and Jool.
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I'm giving this an attempt. I've built a lot of planes that can take off from the sea, but I've never done a submersible mission before. So this a challenge. Depending on what payload I bring, I will probably design a new sea plane around it.
I want to make sure I don't break rules before I start. Mod's in question are VesselMover and Animated Attatchment. Can I leave them installed and not use them, or must they be removed. As far as I know, you have to be stopped to use Vesselmover. Animated attatchment changes the way stock parts work if they are attatched to payload doors or canards and things like that. Practical to have it installed and not use it, allowed?
Second thing is about doing the science right... and command chairs.
I came up with this little rover that sinks. (the camera is not stock, but I can remove it). It could drive forever on 6 RTGs, and transmit science. But it cannot float or swim. If I want to recover the goo, rather than just observe it, I can send a Kerbal down and have him swim up EVA style. Is this allowed? Do we want to remove the goo and bring it to Kerbin, or Is transmitting science the same?
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By recoverable, what do you mean exactly? It could mean that the probe floats up, a scientist removes the goo, takes it in the command pod and goes home. Or it could mean that the goo canister is recovered. Or it could mean everything is recovered.
Fleabag Challenge: Fly plane from KSC to Island using Fleas only
in KSP1 Challenges & Mission ideas
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24 kerbal seats with 18 flea engines