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Is a one day, solar polar race possible?


Tricky14

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On 9/30/2018 at 12:23 PM, 5thHorseman said:

Kerbin is 600km in radius so you need to go 2*pi*600/4 or about 942km, or let's say 1000 for easy math and to account for deviations.

You have 3 hours from sunup to sundown.

To travel 1000km in 3 hours, you need to go 333km/hr or 5.55km/m or 92.5m/s.

That's about 1.6 times your max speed.

I don't know how much more time you get at the poles due to the sun taking longer to set, but don't think it's that much? If it gave you an entire extra hour you'd need to go 250km/hr or 4.17km/m or about 70m/s, which is still not doable.

Also you'd have to drive a rover for 3 (or 4, or 5) hours non-stop without making a single mistake, or multiple quicksaves that eat into your average speed.

What he could also do is drive north west, to "follow" the sun, you would be able travel further that way, right?

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5 minutes ago, TheKorbinjer said:

What he could also do is drive north west, to "follow" the sun, you would be able travel further that way, right?

Yes although this really only works above 45 north unless you can cross ocean.

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8 hours ago, vyznev said:

Yeah, but running stock electric props on solar power has its own set of challenges. There was some discussion of it in another thread a while ago, but I don't recall anyone actually managing to get it working efficiently:

 

I present: The Spark 01:

It's a very stable 2.2-tonne low-wing monoplane that can fly sustained at 57 m/s as long as it is more or less perpendicular to the sun angle. Power reduces if sun angle changes too much. Engine is 5 small SAS wheels and 16 panels, plus a bearing. Stock Aircraft in stock aero:

9imd3QS.png

Edited by Pds314
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Anything is possible, you just have to think and come up with ideas. I would try using RTGs and lots of batteries, with the large solar panels to store as much energy as possible before daylight is gone.

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Just now, The_Cat_In_Space said:

Anything is possible, you just have to think and come up with ideas. I would try using RTGs and lots of batteries, with the large solar panels to store as much energy as possible before daylight is gone.

RTGs are surely cheating in a solar power challenge, and with batteries, you could probably just build something that wouldn't need external power that stages off the dead batteries as it goes.

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Just now, Pds314 said:

RTGs are surely cheating in a solar power challenge, and with batteries, you could probably just build something that wouldn't need external power that stages off the dead batteries as it goes.

RTGs still technically produce electricity so they are counted, right?

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53 minutes ago, Pds314 said:

Jet engines produce electricity. I don't think we're allowed to use them though.

You're missing my point. What I'm trying to say is that the RTG is counted as an electrical part because it exclusively produces electricity. Jet engines consume liquid fuel and intake air to produce thrust and generate small amounts of electric charge while they are running.

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4 hours ago, The_Cat_In_Space said:

You're missing my point. What I'm trying to say is that the RTG is counted as an electrical part because it exclusively produces electricity. Jet engines consume liquid fuel and intake air to produce thrust and generate small amounts of electric charge while they are running.

Well, you two certainly do seem to be kind of talking past each other.

The title of this thread says "one day solar polar race". Running on solar power alone provides several additional challenges that using RTGs, fuel cells or other non-solar power sources would circumvent, like the extra drag added by the panels and the (kind of obvious) fact that solar panels stop working at night.

Sure, RTGs have some challenges of their own, such as their relatively high mass-to-power ratio and (in career mode) their high cost. But if you're playing in sandbox mode and your craft is not mass-limited, using them is kind of a no-brainer. Unless, that is, you want the extra challenge of running on solar power alone.

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3 hours ago, vyznev said:

Well, you two certainly do seem to be kind of talking past each other.

The title of this thread says "one day solar polar race". Running on solar power alone provides several additional challenges that using RTGs, fuel cells or other non-solar power sources would circumvent, like the extra drag added by the panels and the (kind of obvious) fact that solar panels stop working at night.

Sure, RTGs have some challenges of their own, such as their relatively high mass-to-power ratio and (in career mode) their high cost. But if you're playing in sandbox mode and your craft is not mass-limited, using them is kind of a no-brainer. Unless, that is, you want the extra challenge of running on solar power alone.

Their power/mass isn't even that bad when you consider that solar panels are often inefficient at pointing in the correct direction. I.e. a cylinder perpindicular to the sun is like 31.8% efficient. A sphere is 25%. Unless cost is critical, RTGs are often "just better" unless the panels can reliably point at the sun.

Edited by Pds314
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It has been a while since I've dug into KSP aerodynamics, but IIRC shock cone intakes have a lower drag coefficient than pretty much any other 1.25m part in the game besides the tail connector.  If you replace your current nose cones with shock cone intakes, it may gain you a bit of speed.

 

EDIT:  I just double-checked the .cfg files for the shock cone intake and the PartDatabase.cfg for the Advanced Nose Cone A, and the game hasn't changed them--the shock cone intake has a Cd of 0.3, and the ANC A has a Cd of 0.3477.  The shock cone intake is 40kg heavier than the nose cone you're using, however (120kg vs 80kg).

Edited by zolotiyeruki
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