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[UNOFFICIAL/FANMADE] 0.17 Discussion Thread 3

rasheed

By rasheed
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Tommygun

Tommygun

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Okay, because everyone is freaking out about it, here are the stats for the NTR:

The TWR is greater than 1 for moderate payloads, enough that I was able to use 3 engines mounted radially as a Mun landing vehicle:

This single vehicle was able to perform TMI, MOI, Landing, takeoff, and return, and probably could have re-inserted itself into Kerbin orbit as I still had the small radial tanks available.

Very nice, I'm happy to see a NERVA that has a smaller thrust, I just wish it was shorter.

Something that the landing gear could clear, so I would need just one engine. I guess I can rescale it a little bit.

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Rickenbacker

Rickenbacker

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Actually, Orion did get (slightly) beyond the drawing board...

A small-scale proof-of-concept test article was built and flown using chemical explosives. Video here (jumped up to the flight):

Wow, I hadn't seen that! Thanks. So it did actually work, but was killed by politics :(. We could have visited Jupiter in the 80's!

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szpw

szpw

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When I saw that picture of the Mun over Kerbol, I literally thought it was a spacecraft re-entering the atmosphere with some sort of new effect. Upon closer inspection, it is not however.

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Accelerando

Accelerando

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Wow, I hadn't seen that! Thanks. So it did actually work, but was killed by politics :(. We could have visited Jupiter in the 80's!

Even if politics delivered the killing blow, Orion wasn't a very powerful contender for space exploration from the start. Any and each Orion booster would be titanically more expensive than any launch system to date as it would be a commitment to building a miniature space program in itself for questionable returns.

Orion's high cost- and propellant-efficiency at lifting thousands of tons of payload and lower efficiency at smaller tasks meant that the only real way to get the most bang for the space program buck would be to launch (a significant fraction of) the maximum load, ideally a crewed mission. A 40m diameter Interplanetary Orion could have delivered 1200 tons of payload to the Lunar surface  about 10 times more mass than the third stage of the Saturn V. A human presence in space can only do so much actual research before the costs of keeping lots of people and equipment alive and running up there start to outweigh the benefits, at a time when space habitation technology was still largely in its infancy (and it remains so today). Launching robotic payloads might be a little better, but would still require building an order of magnitude more new equipment than has ever been launched beyond Earth orbit to date, setting aside the R&D that would be necessary to build Orion's spaceframe to the capability of withstanding over 1000 hammer-blow accelerations once a second for extended periods.

On topic, that engine really is sexy, but I feel that Nova's parts aesthetic clashes a bit with the textures of the 1m fuel tanks. I hope those get some reworking sooner or later.

Edited by Accelerando
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karolus10

karolus10

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True we should compete to realistic engines and crafts, even if little green jelly Kerbals are flying on ICBMS..

You, totally missed my point - I only compare Specific Impulse and TWR of real engines and kerbal ones, thrust and size has nothing to do with this: smaller craft of course use smaller engines with less power but some ratios could be conserved ,especially if real numbers made life in KSP easier :).

Also better TWR aren't really mean more power - if you add more thrust to engine with keeping same Isp wasn't change ÃŽâ€v you could get from same ship because it burns fuel faster too, so things are still balanced :).

Also I must admitt, that Nova are right that new stock NTR engine (and admire their model style :)) is quite powerful, but they low TWR make interplanetary burns 2x/1.5x longer they could be take with better and more realistic TWR.

Also using NTR engines (even with improved TWR) could be huge waste for mun/planetary lander or launch vehicle, because You could with little effort go to the mun surface from LKO and go back to Kerbin with small lander engine and 2m half tank.

There was serious hopes and considerations in past of using nuclear rockets for making launch vehicle or SSTO, but it really doesn't pay off - you can't made SSTO using engines with so low TWR (and I'm talking about maximum possible performance) like NERVA, and other types of nuclear rockets will had lower performance than chemical rockets or their designs make afraid to launch them *near (*quite far away) habitable areas or fear close to them at all :cool:.

Also nuclear reactor from NTR engine can't blow like a nuke, first it use other isotopes of plutonium/uranium than nukes, also risk of contamination will be small because core of NERVA engine could survive train crash or throwing out of the plane without a serious damage of critical components (in early 50s it was few explosions, one due intentional meltdown and one during Fuel lines malfunction and getting reactor dry).

EDIT_1: BTW, also using engine throwing super-heated hydrogen (NTR's not burn fuel, only heat them) in atmosphere aren't really good idea :P (and causing hydrogen to burn before it leaves nozzle has bad impact for Isp too).

EDIT_2: Also Orion project couldn't succeed - nukes really aren't cheap and it need whole bunch of them, also launching nukes on the orbit during mid of cold war was an sick idea :P.

Edited by karolus10
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Ted

Ted

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Moderator Comment: Please feel free to discuss the Orion project in the Off-Topic board, it's a very interesting topic that deserves it's own thread and is fairly off-topic here. Thanks.

That image of the eclipse is quite amazing, I imagine Jool, with all it's Moons will have it's fair share of eclipses.

A good project for someone for 0.17 (and beyond) would be to note down the time from game start that all eclipses occur and in addition figure out the period it takes for each to occur. Going further, it would also be quite fun to figure out how often all the planets line up.

These are just some of the reasons that the 0.17 update will really take KSP to a whole other level!

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LukeTim

LukeTim

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Moderator Comment: Please feel free to discuss the Orion project in the Off-Topic board, it's a very interesting topic that deserves it's own thread and is fairly off-topic here. Thanks.

That image of the eclipse is quite amazing, I imagine Jool, with all it's Moons will have it's fair share of eclipses.

A good project for someone for 0.17 (and beyond) would be to note down the time from game start that all eclipses occur and in addition figure out the period it takes for each to occur. Going further, it would also be quite fun to figure out how often all the planets line up.

These are just some of the reasons that the 0.17 update will really take KSP to a whole other level!

At the distance from Kerbol that Jool is, unless at least one of its moons is humongous, there'll be no eclipses there.

Transits across Kerbol, but no eclipses.

Speaking of eclipses, though... I wonder if the Devs have any plans to implement umbral/penumbral shading on Munar Eclipses... I know that with the lighting system as it stands this isn't possible, but it'd be sweet to see it in the future.

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LukeTim

LukeTim

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800 Isp! That is amazing! I wonder if there is going to much of a use for any of the other high Isp, low thrust engines now.

It has high Isp, sure... but it is heavy. It's designed for interplanetary missions, of course, and if you're just heading to The Mun or Minmus the lighter engines will still be a better option.

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Magmaros

Magmaros

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Harv/Nova, any chance that we'll be able to turn Liquid/Nuclear engines on and off individually like you can with the atmo engines? so like you could launch, get into orbit, turn off the liquid engines, turn the nuclear ones on, then later on, turn the nuclear ones off and the liquid ones back on?

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RoboRay

RoboRay

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Very nice, I'm happy to see a NERVA that has a smaller thrust, I just wish it was shorter.

Something that the landing gear could clear, so I would need just one engine. I guess I can rescale it a little bit.

It looks like you could put a single engine below the capsule (via decoupler and a small part like an ASAS or little fuel tank) and feed it from 1m outrigger tanks down the sides, with the landing legs attached to the outriggers.

Sort of Nova's lander turned inside out...

eNc3C.jpg

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Tommygun

Tommygun

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It looks like you could put a single engine below the capsule (via decoupler and a small part like an ASAS or little fuel tank) and feed it from 1m outrigger tanks down the sides, with the landing legs attached to the outriggers.

Sort of Nova's lander turned inside out...

Possibly or one of those extra long decouplers that cover the whole engine, if I can get landing legs to attach to them.

We'll see.

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pizzaoverhead

pizzaoverhead

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On topic, that engine really is sexy, but I feel that Nova's parts aesthetic clashes a bit with the textures of the 1m fuel tanks. I hope those get some reworking sooner or later.

I'd imagine at least part of that is due to the long term goal of having a progression of part technology through the game. I'd imagine the low-level fuel tanks would be more haphazard in aesthetic than the more advanced parts like the LV-N ARM or aerospike engines. In alpha our parts are a bit pick 'n' mix through different technology levels.

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olex

olex

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Just wondering, what particular applications will the NERVA have?

Interplanetary travel. With the high specific impulse (more than double that of the chemical rockets), you can make significant delta-V changes using half the fuel, albeit in long burns due to the low thrust (but long burns are perfectly OK for interplanetary flights). Which means you need to lift much less fuel from Kerbin.

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Jay_Em

Jay_Em

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Interplanetary travel. With the high specific impulse (more than double that of the chemical rockets), you can make significant delta-V changes using half the fuel, albeit in long burns due to the low thrust (but long burns are perfectly OK for interplanetary flights). Which means you need to lift much less fuel from Kerbin.

Ok, that sounds very useful.

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eyecikjou567

eyecikjou567

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I like the Idea of the NERVA.

So much energy we can bring up in orbit now.

(Energy = Total Movement Change / Fuel) (ms^2/kg)

So ISP 800 m/s means 800 Ns/kg or 800 Newtonseconds per kg fuel)

A Newtonsecond is about 1 meter and 1 kg per second movement.

If we apply that to TMC (weigth assumed= 1kg) we get 800 meters per second

So the small tanks have about 300 units of fuel (300 kg assumed)

Applied to Fuel and Calced: 8/3 ms^2/kg ~ 3 ms^2/kg

Means this engine would move 1kg (hope its right) at a velocity of 3 m/s² per kg fuel.

I think that is good.

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