ENGINE:VISP should return design vacuum ISP of the engine

[pdbogen]

Ideally we'd have:
ENGINE:ISP:VACUUM
ENGINE:ISP:ATMOSPHERE
ENGINE:ISP:CURRENT

But I'm not sure if that would break compatibility with scripts expecting ENGINE:ISP to just be a number.

[Dunbaratu]

It would break backward compatibility. In this case I don't think there is a good case for a separate ISP object because all it is is a plain scalar number. Having 3 different ISP's as flat numbers makes sense because they are indeed 3 different things.

Unlike, say, velocity, where Velocity:orbit and Velocity:surface are actually just two different ways to express the same exact thing - in two different frames of reference (come to think of it, we could also have a Velocity:target).

[pdbogen]

Works for me. P.S., VELOCITY:TARGET would save me a lot of LOCK RVEL TO VELOCITY:ORBIT - TARGET:VELOCITY:ORBIT.

On October 14, 2014 9:37:59 PM PDT, Steven Mading notifications@github.com wrote:

It would break backward compatibility. In this case I don't think
there is a good case for a separate ISP object because all it is is a
plain scalar number. Having 3 different ISP's as flat numbers makes
sense because they are indeed 3 different things.

Unlike, say, velocity, where Velocity:orbit and Velocity:surface are
actually just two different ways to express the same exact thing - in
two different frames of reference (come to think of it, we could also
have a Velocity:target).

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#273 (comment)

• Patrick

[erendrake]

Question, what are you trying to do with these values?

[pdbogen]

For ENGINE:VISP, my intent was to calculate an upper bound for available DeltaV.

On October 14, 2014 11:57:23 PM PDT, Chris Woerz notifications@github.com wrote:

Question, what are you trying to do with these values?

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#273 (comment)

• Patrick