Frederf
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Posts posted by Frederf
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Does parachute material affect rip strength?
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Is it possible that DRE currently doesn't have a sane way of surviving reentry to Eve?
I've currently got a probe 'stuck' in orbit around Eve and I've tried numerous things, but all end up in destruction.
The probe weighs approx 4000kg (including shields), has a diameter of 1,25m.
It has two 2,5m heat-shields attached to it (stacked on top of each other).
It's deorbited from just above the atmosphere, which results in a velocity of around 3100m/s.
The target periapsis is 78500m which results in a nice 'skip'.
Any and all reentries end in the exact same way, the heat-shield overheats and explodes.
The next heatshield only lasts another second or so and also explodes.
It seems to me the problem is the heat-shields don't have a high enough maximum temperature.
The only work-around I can imagine is retro-rockets. But as Eve is supposed to be the equivalent of Venus
and the Russions managed multiple landings using heat-shields during the 70's I feel that DRE should provide heat-shields that allow for landing on Eve.
I've tried tampering with the part-cfg's. But even raising the maxTemp value of the heat-shields to 50000 still only results
in an ingame maxTemp of 2500 and that simply isn't enough to survive reentry.
Are you using FAR? What is your Cd?
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I am creating a com probe which purpose is to land on Duna and provide an area where I can aim and land a full science rover, analyze the density of the atmosphere, and provide communications back to Kerbin.
Problem:
(Deadly Re-entry mod, 1.25m heatshield on probe.)
While testing in Kerbin, my communotron 32 antenna is breaking under the stress on re-entry, which means that I somehow need to deactivate it during reentry to then reactivate it.
How do I get around this issue?
In my case I genuinely programmed a sequence that involved the antenna raising and lowering such that it had a command to lower the antenna, all the landing instructions, and then one to raise it minutes later and then the thing lands itself and resumes contact. You want the "Toggle" action name in an action group so you can provide both the raise and lower commands as ALT+(#) before the whole sequence even starts.
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BTW, if anyone would like to know. It officially sucks trying to land a probe on the small crater island on Eve with the 74 second signal delay. It took me over 100 tries and several days, but I managed to do it. And you know what, I am NEVER doing that again.
We must be twins as I just did that only with a parachute lander and hoping for flat ground. The difficulty was less but a complex reentry sequence made timing a pain. I think we both need to write kOS scripts for first run accuracy for these kind of missions.
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I don't have that particular cube yet unlocked in the RD tree. Even though I'm sure workarounds exist I was hoping for more enthusiasm toward the root cause. I'm not sure how the drag shielding works exactly but I would hope an exposed connection node or surface blunt to the air stream wouldn't be shielded. Is it nodes or COMs or ray tracing? I don't have that insight.
As a side note I'm aware of the intended construction of the interstage adapter and have used it that way but in this case I wanted the fairings and adapter to depart the craft at different times. What I think would be nice is to have a mode that removed the base+fairings whole, say if you blow the sides it separates the craft (triggers the base decoupler remotely) or if the base is triggered first the sides stay glued to the base and the base decouples directly.
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Top (root side) to bottom:
Top of craft
Squad decoupler
Procedural interstage adapter w/ 4 conic fairings
DRE 1.25m heat shield
Bottom of Craft
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Well, it's happened.
Through a slight miscalculation in saving and loading I've stranded a vessel because the command queue isn't saved with save game files and thus a craft that was absolutely on track to reestablish contact on its own has suffered short term memory loss and isn't going to do the set actions that makes that happen.
The command queue REALLY REALLY REALLY REALLY needs to be saved. Did I say REALLY enough?
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I'm having a slight issue with a DRE shield below an interstage fairing adapter. The drag (FAR) is zeroed out for the parts inside the shells above it but also the shield applied to the bottom which makes reentry excruciatingly long and hot at Cd 0.002. Could thes shielded volume be adjusted to be more accurate?
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Not really. I can't find the orbital speed for a 70km circular around Kerbin with it for example. It's also not so quick and easy to use. Altitudes are in SMA/ecc and calculations take a few seconds.
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Not so much. This is orbit mechanic http://forum.kerbalspaceprogram.com/threads/4374-KSP-Orbit-Mechanic-1-2a-Optimize-Your-Orbits?highlight=orbit%20mechanic
Something where I can ask what is the orbital period of a 32 x 48.5 around Eeloo or what are the transfer dVs from 70x70 to 100x100 around Kerbin or a thousand other whatifs.
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Been using Orbital Mechanic, a small Java app, for all my simple orbital calcs but I've stopped using it since it's out of date and only includes Mun/Minmus in the other bodies and I'm going interplanetary.
Is there a current tool for elliptical orbit data on all current KSP bodies, maybe some transfer details? I have KSP_TOT which handles the advanced interplanetary injections and flyby gravity brakes but simple back of the envelope calcs I'm without a tool.
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I know it's not trivial but if these parts could be procedurally scaled the number could be cut down drastically and be more useful overall. Often the smallest parts are still too large to make folding rovers and probes.
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They don't work like pipes. They work more like docking ports. If you hook a pipe directly from a Kethane converter to a fuel tank, the tank will NOT fill.
Trust someone who found this out on Mun.
You're not the only one. I make sure to keep buffer tanks on the vehicles so that small amounts can be transferred and TAC fuel balancer does the manual flow operations.
However Id still love for KAS to have a small electrical pump part that handles this sort of thing.
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I'll post it later but it looked rather tame. I think a couple of BACC boosters with a skipper throttled lightly for steering control. TWR was no more than 4. Perhaps a high Cd in the 1-2 range is to blame; I'll have to check if it was that high.. As sensible as the craft looked you know how weird aero issues can crop up.
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Indeed you should imagine leaving the Mun SOI "cage" is like jumping from a moving car. If you barely escape it you'll be going the same speed as it. To fall down for reentry you need to escape it rearward with some extra speed rearward. If you find what appoapsis speed for a 11400x30km orbit is and subtract the Mun's orbital speed, that's what you need to carry extra as you escape it's SOI.
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Are you sure? It has been stated a couple of times that it is nearly impossible to hit terminal velocity. One of the reasons is that the terminal velocity is also increasing along with your TWR.
I don't know if I was getting there exactly but my speed readout in surface navball exceeded the FAR fight data readout. TV increases with altitude (air density) so it is a game of catchup but it stays pretty low for the first 5000m or so. After 20,000m, yeah, forget it.
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Frederf: (not you specifically, but) what is it with the terminal velocity fixation? It's ~400m/s at sea level and you need one _heck_ of a TWR to even approach it after sea level. Seriously, you _will not_ be overspeeding in atmosphere with FAR. The real issue is burning so far from apogee that all you're doing is raising your apogee, not perigee.
I've taken it onboard that TV is the speed at which dV losses during (at least vertical) ascent are minimized. Assuming the craft steers properly and stays in one piece it should be the minimal dV to orbit. The best ascent would be to 50/50 your dV losses from effective gravity (cosine attitude) and aerodynamic ones until your Ap was as desired then MECO and circularize at Ap. And I absolutely can exceed TV during ascent without too much difficulty. MRS's thrust fix means that a small TWR at launch can quickly surpass TV as thrust is increasing and weight is decreasing.
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The point of TWR 1.5 is that TWR is expected to grow as the atmosphere recedes. You'd love to have TWR infinite up to terminal velocity then 2.0 to stick to TV all the way up. Most RL rockets aren't throttleable and even if they were max TWR adds weight so spending time at partial throttle is wasted weight penalty. With thrust stuck on max combined with thrust improving as you approach vacuum, your initial and final TWR will bracket 2.0. If you start at 2.0 then the average will be >2.0 and your total dV losses will be high due to aero. You'd want to balance it so you spend time slow which has a gravity penalty and time fast which has an aero penalty and minimize their total.
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Eh, no, RealChute does not have that armed state, on purpose of removing the furstration when you accidentally press space in space without wanting to.
Those are two different ideas, no? I could see disabling the spacebar-parachute link but the armed-state is a different ball of wax. I guess I'd save myself a lot of white hairs to start kOS scripting these landings for better first run chances of success.
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A button to update the custom attitude (instead of off/on) would be great. A "zero delay" button would be handy. Sorting queue by which is scheduled first would be welcome.
The ability to save and load without breaking the Flight Computer state is a big big want.
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A drag coefficient of ~0.002 is for very, very low skin friction drag only, with no significant pressure effects. A drag coefficient much higher than that would include pressure effects, like shockwaves, air being compressed, pressure much lower than the ambient, etc.
Odds are that if your DRE shield isn't making enough drag that the fairing is somehow picking it up by mistake... try putting some extra space between the fairing and the shield and see if that changes things.
I thought so. I mean the blunt end of the shield approaches definition of Cd=1.0 by simple geometry. Is reference area the cross sectional area or equivalent? (The number Cd is multiplied by or rather the flat plate the shape is divided by to get Cd).
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With stock parachutes you get a blue "armed" state that's really handy when working with RT2 delays of a couple minutes. I noticed RC doesn't do this armed state or maybe just not the colored icon.
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How realistic is it to have Cd values that range from 0.002 to about 1.5? I've been making aero shells with a DRE shield on the bottom and a procedural fairing top and the suckers have like zero drag.
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Heat and Gs will damage parts which you can inspect/fix in EVA. It's probability based.
To protect against the heat fairings with FAR help a great deal.
I stranded Jeb on Eve...
in KSP1 Gameplay Questions and Tutorials
Posted
Try using some of the lighter-than-aircraft mods. Use buoyancy and Eve's atmosphere for you instead of against.