Update Deepstar development

Izack

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@80mileshigh and Solarliner

80mileshigh asked me, and so im giving you and Solarliner the permission to use my Deepstar- and Lander-config.
I calculated the fuel mass to 12751mT, Sky captain did own calculations and got 13500mT. So you can set it between 12760 and 13500mT. It has no big effect. But i propose to increase the Isp to get more DeltaV! If we use Isp 200000 we get dV of 400km/s, before only 193km/s. But the acceleration goes down to 1,28m/s², well enough for that huge ship (before 2,8m/s²) because a fusion drive can run like an afterburner. We give fuel directly into the plasma beam, the fuel consumption rate goes high and the thrust increases, but the exhaust velocity (ISP) falls down.
You can test some settings, but alltime use the same multiplier/divider for Isp, thrust AND attitude thrust. Ofcourse higher Isp numbers enabling more comfortable travel speeds, but maybe TransX and IMFD getting trouble, because they are not made for low thrust vessels.

Perhaps my head is fuzzy, but are you suggesting a two-mode switchable engine (afterburning and non-afterburning) ? Because that's totally do-able. :thumbup:

There could also be a function for [math]I_{sp}[/math] variation based on throttle setting.
 

Urwumpe

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I would calculate the exhaust power as reference there. It is simple Thrust force multiplied by specific impulse.

In the ideal case, your exhaust power would remain constant, when you vary mass flow rate by injecting more reaction mass into a nuclear thermal engine.

In reality, there is one ideal design point, where you have peak power, and moving away from this ideal will lower the exhaust power. And in reality, this ideal design point would even change over the engine life time, as the engine components age.
 

Izack

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While we're at it, I'm searching for a standard to live up to regarding reactor output for a spacecraft like Deepstar. I'm assuming this vessel carries a nuclear reactor of some description. Bimodal NTR perhaps, considering the layout.
 

Izack

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why not tri-modal?

Okay, well, multi-modal. Add more modes!!

Reading around Atomic Rockets, I see some engines with 1000 MW power requirements. The logical power source I've been tinkering with at the moment has 100MW, 400MW and 1200MW generation modes, but this needs to be refined. Unfortunately that website doesn't have much information regarding power production and consumption.
 

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@Izack and Urwumpe

Good idea with the thrust/Isp curves, but this needs a DLL and i can't write DLL's.
But its not a bi-modal or tri-modal engine design, its a fusion drive! Ok, the ship's exhaust nozzle looks like NTR propelled, but its only because 80mileshigh did not define the engine at his creation in the past. He saw a similar design of the ship at an old illustrated space magazine and was falling in love with it :). After that he thought it must be "nuclear propelled in some way". But with solid core NTR we could never reach some hundret km/s, only some km/s for flying to mars and back in 2-3 years, not really comfortable and no big advantage to actual chemical engines. The best solution is a fusion engine, which produces enough energy to propel the ship and to support the electrical board systems. The energy outputlevel would be from 3-8GW !!! But its very difficult to made a bi-modal fusion engine, because we have official at time no working fusion reactor (maybe the secret Navy Polywell WB8 reactor). But dont be worry, that is no problem for a spaceship! Its possible to operate a fusion drive which consumes the needed electrical energy from one/many nuclear fission reactor(s)! But to reach 2 or more GW it would be a monster reactor, the Deepstar is a way to optimistic for that, definetly not near tech. I give you an example, the VASIMR engine has at 12MW electrical power 1,2kN thrust at maximum, exhaustvelocity 50 000m/s. With 200MW it would have 20kN, with 2GW 200kN (Deltaglider-level), all only at 50 000m/s Isp. You see the problem? Ok deepstar uses not the "cold fusion" VASIMR engine, it uses hot fusion. The Isp goes without afterburner to 1000 000 m/s, but with very low thrust. With afterburner we have 200 000m/s, but we have every second to inject some tens of kilogramm of reaction mass extra into the plasma beam.

@80mileshigh
So my suggestion to 80mileshigh, please could you redesign the exhaust nozzle, from its actual NTR style to a nice fusion plasma thruster? Because a NTR-nozzle would melt in seconds, when a 100mio degress hot plasma is hidding it.
A solution to increase the thrust without lowering the Isp is a bundle of 3-4 plasma thrusters and would be a nice backup, when one of them has a failure :thumbup:.
 
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80mileshigh

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@80mileshigh
So my suggestion to 80mileshigh, please could you redesign the exhaust nozzle, from its actual NTR style to a nice fusion plasma thruster? Because a NTR-nozzle would melt in seconds, when a 100mio degress hot plasma is hidding it.
A solution to increase the thrust without lowering the Isp is a bundle of 3-4 plasma thrusters and would be a nice backup, when one of them has a failure :thumbup:.

Sure thing, can you post an image of what it should look like?

Also, does anyone have expereince implementing UMMU with Artlav's SC3 converter? I can't seem to make the UMMU appear at a dock, despite defing the docks in the .ini. Rather, it appears at the centre of the mesh.
 

SolarLiner

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Sure thing, can you post an image of what it should look like?

Also, does anyone have expereince implementing UMMU with Artlav's SC3 converter? I can't seem to make the UMMU appear at a dock, despite defing the docks in the .ini. Rather, it appears at the centre of the mesh.

I converted the SC3 Shuttle PB Mk2 to DLL using Artlav's converter. It seems it can't choose a dock because they are several defined. Instead it declares its EVA point to the exact center of the ship (at least I think, because the Shuttle PB Mk2 has only one dock). So you have to change it in the "clbkSetClassCaps", in the function "Crew.SetMembersPosRotOnEVA(Vec3, Vec3)"

Anyway, this part of the code should be rewritten correctly to the desired parameters.
One last thing: since the Deepstar has multiple docks and UMmu can handle only one dock, there is a trick to do, changing the internal camera pos/rot and of course the active dock (by "translating" the airlock shape and the pos/rot on EVA). But it is just for the deepstar :lol:
 

80mileshigh

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I converted the SC3 Shuttle PB Mk2 to DLL using Artlav's converter. It seems it can't choose a dock because they are several defined. Instead it declares its EVA point to the exact center of the ship (at least I think, because the Shuttle PB Mk2 has only one dock). So you have to change it in the "clbkSetClassCaps", in the function "Crew.SetMembersPosRotOnEVA(Vec3, Vec3)"

Anyway, this part of the code should be rewritten correctly to the desired parameters.
One last thing: since the Deepstar has multiple docks and UMmu can handle only one dock, there is a trick to do, changing the internal camera pos/rot and of course the active dock (by "translating" the airlock shape and the pos/rot on EVA). But it is just for the deepstar :lol:

So there isn't a non-coding solution; a simple change in the .ini to make, or something like that?

This has been my stumbling block, but I'll just go ahead and release a basic non-UMMU version as a stop-gap. After this I can work to order for Izack, who can actually code. :)
 

Izack

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@Izack and Urwumpe

Good idea with the thrust/Isp curves, but this needs a DLL and i can't write DLL's.

I'm currently working on a module for this. :tiphat:

After this I can work to order for Izack, who can actually code. :)

Well, you're the inventor, so I'm really working to your order.
 

Axel

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80miles wrote:
Sure thing, can you post an image of what it should look like?

Yes, here are 2 links with nice pictures, the first is of a near tech VASIMR plasma drive, the second of a fusion drive. They are very similar:

http://spectech.bravepages.com/DST_Image_Plasma_Exhaust.jpg

http://msnbcmedia.msn.com/i/MSNBC/Components/Photo/_new/100108-space-2010-hmed-1015a.jpg

@Izack
Very nice that you work on a module for this!
I worked some years before with NickD at his awesome VASIMR Bekuo-addon, as consulter and test pilot before the release.
[ame="http://www.orbithangar.com/searchid.php?ID=3212"]USS Bekuo VASIMR v.1.01[/ame]
Maybe its a little bit helpfull for you, because it uses allready thrust/Isp-curves :thumbup:.
 

Izack

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I worked some years before with NickD at his awesome VASIMR Bekuo-addon, as consulter and test pilot before the release.
USS Bekuo VASIMR v.1.01
Maybe its a little bit helpfull for you, because it uses allready thrust/Isp-curves :thumbup:.
I've always enjoyed this addon's unique challenge. Good job, both of you. :thumbup:

Without source, though, it's not exactly helpful except as an inspiration. Thank you kindly, though.
Am I on the right track with something like this?:

I wonder what the exhaust for such an engine would look like in a vacuum. Presumably a very bright, pale blue glow from the interior of the nozzle. Perhaps an Orbiter spot light to illuminate a vessel unfortunate enough to be caught in the thrust beam.
 

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There are some examples of the VASIMR engine exaust on youtube,I will try,and find them for you later today when I get some more time.:thumbup:

OK, turns out there is a couple pages of VASIMR engine tests on youtube,just search for VASIMR.
 
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Izack

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There are some examples of the VASIMR engine exaust on youtube,I will try,and find them for you later today when I get some more time.:thumbup:

OK, turns out there is a couple pages of VASIMR engine tests on youtube,just search for VASIMR.

This is no VASIMR, though. It's a fusion torch.
 

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@80mileshigh
Yes the new engine looks well! Four nozzles is although a good redundance system (like at the last launch of SpaceX,CRS1). If one of them has a failure, then we deactivate simply its opponent and continuing the space trip simply with two engines.

Izack wrote
I wonder what the exhaust for such an engine would look like in a vacuum. Presumably a very bright, pale blue glow from the interior of the nozzle. Perhaps an Orbiter spot light to illuminate a vessel unfortunate enough to be caught in the thrust beam.

The looking of a plasma exhaust (vasimr and fusion) depends strongly of its working stuff: the choosen electrical power level and the mass flow rate. Generally:
more electrical power to the drive streches the exhaust beam, because the exhaust velocity of the plasma particles is then higher, more reaction mass to the drive (afterburn mode) will light up the beam from blue to nearly white but makes it shorter and wider, because the lower exhaust and some of the not well neutralized particles will fall back into the engine. Vasimr and fusion exhausts should be looking very similar. Fusion exhaust looks most more like a beam, vasimr exhaust looks like a plume because the lack of high power nuclear space reactors force us to inject more reaction mass to compensate to low thrust rates.
 
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80mileshigh

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Back in business:

[ame="http://www.orbithangar.com/searchid.php?ID=5921"]Deepstar 2.1[/ame]

Again, apologies for the delay.

I'm looking forward to working on new features now.
 

Izack

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An excellent release! :thumbup:

---------- Post added at 03:57 PM ---------- Previous post was at 03:16 PM ----------

Now, regarding future features, it's probably best to work from the ground up. First, some thoughts on attitude control...

I think the ACS is too powerful currently. The mass and length of the vessel in my imagination would require too much power from the thrusters, and introduce heavy stress on the structure, and then there's the discomfort of high angular accelerations on the crew and any unbound objects in the ship. I might suggest lowering the power on the attitude thrusters in the future.

How useful are the translation thrusters on the vessel? With something of the Deepstar's size, it must be that anything docking with it will be smaller and more mobile (Deltagliders and landers.) The Deepstar itself I think could probably do with simply +Z and -Z thrusters for fine-tuning of the orbit, and other vessel-vessel manoeuvring would be handled by the other vessel.

---------- Post added 03-12-12 at 09:54 AM ---------- Previous post was 02-12-12 at 03:57 PM ----------

It looks like there are some mesh differences between the 2.0 and 2.1 versions of the Deepstar mesh; my centrifuge animation broke and causes a CTD. After the first timestep. Switched back to the 2.0 mesh for now. Could I perhaps get a copy of the new INI that the DLL was made from?

---------- Post added at 01:37 PM ---------- Previous post was at 09:54 AM ----------

Attitude control is being provided by twelve groups of four MHD thrusters each. Attitude control is accordingly slow, and should be performed with care and deliberation - this will require more planning from users, and more careful control of attitude, as it is not possible to orient the spacecraft 60 seconds before a burn starts. I recommend being oriented well in advance of any planned manoeuvre.

I'm also trying my hand at custom exhaust textures, both for the primary fusion beams and the MHD thrusters...and failing utterly. Perhaps 80mileshigh or someone else would like to contribute?
 
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