[Flight Question] Specific Impulse of DGIV

[goaowonk]

I've been looking for the Delta Glider IV's engines Isp, and I havn't found it anywhere, only for the default DG (4·10^4s). Well, I could estimate it by calculating delta-v and delta-mass, but I'm sure that's a very unprecise way.
So, does anyone have it?

[PeterRoss]

As far as I know DGIV has the same ISP of 4000 s (40000 m/s). You can use

Burn Time Calculator 2.32

Burn Time Calculator 2.32

to determine engine's ISP.

[sorindafabico]

Also, you can change the ISP in "...Orbiter/Sound/deltagliderIV/Dg4config.exe". There are four options in the "fuel reserve" menu.

[SolarLiner]

Quote:

Originally Posted by PeterRoss

 As far as I know DGIV has the same ISP of 4000 s (40000 m/s). You can use Burn Time Calculator 2.32 to determine engine's ISP.

Nope. The GD4 Config tool edits the ISP by changing the engine (Mark I to Mark V) So it depends from the player's choice.

[PeterRoss]

Quote:

Originally Posted by SolarLiner

 Nope. The GD4 Config tool edits the ISP by changing the engine (Mark I to Mark V) So it depends from the player's choice.

Nope Config tool can change its trust, not ISP.

[sorindafabico]

Config tool changes BOTH thrust and ISP.

When you set up fuel reserve as "just ISS", DGIV ISP is lower than "trip to Jupiter".

"Just ISS" is 36000 m/s, "ISS and The Moon" is 44000 m/s. I don't remember the values to Mars and Jupiter presets.

Mark I-V are presets for thrust.

[N_Molson]

Quote:

Well, I could estimate it by calculating delta-v and delta-mass, but I'm sure that's a very unprecise way.

If you use the Tsiolkovsky equation, you'll get a very precise result...

[goaowonk]

Quote:

Originally Posted by N_Molson

 If you use the Tsiolkovsky equation, you'll get a very precise result...

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I meant I could use that formula with Isp·g0 instead of ve, but it means that I need to get the values for delta-v, initial mass and final mass (delta-mass=final mass - initial mass) several times and then get Isp for each case. So then I can get the regression value... but my problem is this:
If I do several big burns, and take note of the three values, delta-v changes its increasing rate. If I do shorter burns (I've tried with 10s burns), delta-mass is too near to 0... that makes errors increase a lot.

Anyway, thanks for the help.

P.S.: I'd prefer not to use too many add-on MFD's, because they use the program's core instead of sensors or something like that, and are unrealistically precise and economic when maneuvering. Even Orbit MFD makes everything much easier...

[Scattykat]

Here might be of help: http://www.strout.net/info/science/delta-v/ along with: http://www.braeunig.us/space/propuls.htm and: http://www.answers.com/topic/specifi...rocket_engines