Space Station - Length of a Spiral

I have a question about this morning's Math in the News problem on Twitter:

https://twitter.com/MathInTheNews

The problem is:

This morning, astronauts flew to the International Space Station (230 mi up) in 6 hours, circumnavigating Earth 4 times. What was their mph?

Then the advice given was:

Today's source: http://www.telegraph.co.uk/science/space/9961272/Astronauts-fly-to-International-Space-Station-in-under-six-hours.html The trip length is down from 50 hrs. Use a distance of 4*2π(3959+115); four times avg circumference.

My question is:

What's the actual distance? Using the average circumference makes sense for that level (Alg 1/ Geometry) as an estimate, but it seems like the outer loops will have more added length than the inner loops will have shortened length. On the other hand, circumference is a linear move from the radius, so maybe it will balance out.

Any thoughts that you have- even if someone else has posted an answer- would be appreciated. Thanks in advance!