Simulating behaviour on other bodies?

[XrayLima]

Ok, not sure if this is going to be a discussion or a call for gameplay advice, but I'll put this here to start.

I'm building a Minmus or similar mass body 'skimmer' basically a small ship with ions or RCS underneath, a seat or two and vertical facing probe core.  By setting max acceleration using MechJeb to the same as acceleration due to gravity, I can get it to hover and use RCS to propel it allong.  Basically it's a quicker way to move about than a rover (unitl power/monoprop runs out).....

So anyway, here's the question.  I want to test it.  I have three options really - hack gravity, which sets gravity to fixed very small value and doesn't match target G, hyperedit to the location I want to use it on, or a combo of hack gravity and add exta mass, which messes the ships inertia and responsivness up.

I don't really want to use hyperedit, as I'd like to visit these places "for real", I'd like to adjust the hack gravity hack level, but don't know how and that feels "cheaty" too and I'm struggling to find a suitable way to create Kerbin equivalent models to test fly.

What do you folks do to simulate craft before sending them to their target bodies?  Or do you just suck it and see?

[Xavven]

I use Kerbin as the test area and give the vehicle bigger engines to compensate. You'll never know for sure if your solution works until you get there, but with a little extrapolation you can get fairly close. Half the fun is making iterative improvements resulting from experience.

[autumnalequinox]

I use KCT (Kerbal Construction Time) which has a built in simulator.  It costs funds and requires you first visit the body with a probe or manned.  I have also heard good things about KRASH, another sim mod, which has similar requirements.

I typically test all my wild ideas  at least once.

[The_Rocketeer]

Use a SSTO to reach Minmus and test it there. For Tylo I'd probably not recommend this.

[steuben]

hyperedit will also let you hack planets as well as ships. so you can tweak the gravity of kerbin down to minmus... or the other way if you want to test things out.

 

[eddiew]

30 minutes ago, autumnalequinox said:

I use KCT (Kerbal Construction Time) which has a built in simulator....

This would be my suggestion too   Making you pay for it stops it feeling so cheaty.

That said, I have a personal rule to not simulate landing on any body I haven't dropped at least a probe on, because there's no difference in visuals twixt simulated and 'real' missions, so it kind of spoils the first landing.

[teag2]

Testing this design on Kerbin is probably impossible, because the design you mentioned will lose all its inertia to drag. In order to properly test it, you'll have to be on Minmus one way or another.

[autumnalequinox]

On 6/6/2016 at 10:50 AM, eddiew said:

This would be my suggestion too   Making you pay for it stops it feeling so cheaty.

That said, I have a personal rule to not simulate landing on any body I haven't dropped at least a probe on, because there's no difference in visuals twixt simulated and 'real' missions, so it kind of spoils the first landing.

Another good mod for that:  Mission Controller 2 has an option to set a "revert cost" of any amount desired.  Also feels less cheaty  

[cantab]

I just test on or near Kerbin and extrapolate the results. In general you can use Kerbin to test craft for most atmo bodies, Mun for larger vacuum ones, and Minmus for smaller vacuum ones. To be honest Minmus is pretty forgiving, you can make your design and unless you make a silly oversight it should work. I had a lot of fun with a modded ion hovership on Minmus myself a few versions ago. On the other hand Kerbin's atmosphere renders ion engines nearly useless and other engines weakened.

You could attempt to build something like this if you want: https://en.wikipedia.org/wiki/Lunar_Landing_Research_Vehicle

However that's not a trivial build. The jet engine needs to support the test vehicle at its centre of mass, and always point straight up and deliver constant thrust however the rest of the test vehicle tilts around and throttles. Infernal Robotics or/and KAS would probably help.

I just test on or near Kerbin and extrapolate the results. In general you can use Kerbin to test craft for most atmo bodies, Mun for larger vacuum ones, and Minmus for smaller vacuum ones. To be honest Minmus is pretty forgiving, you can make your design and unless you make a silly oversight it should work. I had a lot of fun with a modded ion hovership on Minmus myself a few versions ago. On the other hand Kerbin's atmosphere renders ion engines nearly useless and other engines weakened.

You could attempt to build something like this if you want: https://en.wikipedia.org/wiki/Lunar_Landing_Research_Vehicle

However that's not a trivial build. The jet engine needs to support the test vehicle at its centre of mass, and always point straight up and deliver constant thrust however the rest of the test vehicle tilts around and throttles. Infernal Robotics or/and KAS would probably help.

[SorryDave]

For unusual designs like you suggest, I use sandbox to test my designs. I build overpowered rockets and send them to the destination.

When designing, KER can be set to determine TWR for different bodies and RCS build aid is great for lining thrust to center of gravity. 

I then copy my successful designs to my career save and/or an archive folder.

[AbacusWizard]

I usually just test the thing on Kerbin. If it works there, it'll work anywhere except Eve. (It'll probably be disgustingly overpowered, but it'll work.)

 

Alternatively: if it works on Mun, it'll work on any moon except Vall, Laythe, and Tylo (and will probably work on a few of the smaller planets, too).

 

Honestly though the main things I usually check--by the numbers, not by testing--are thrust-to-weight ratio (can it lift its own weight when it's on the ground?) and ∆v (does it have enough fuel to land, muck around a bit, and get back into orbit?) for each body I'm intending to land on.