Will solar flight kill space business?

[orionrider]

Neilsox, check this:

http://en.wikipedia.org/wiki/Jet_stream

Jet streams are fast flowing, narrow air currents[...] The strongest jet streams are the polar jets, at around 7–12 km (23,000–39,000 ft) above sea level, and the higher and somewhat weaker subtropical jets at around 10–16 km (33,000–52,000 ft).

Typically:

http://www.atmosphere.mpg.de/media/archive/1090.gif

Unmanned 'stratellites' are operating in the stratosphere, around 20 km high. That is 65,000ft. Out of reach of these fast winds.

they could be tethered at about 15,000 feet [...] Since each can relay data over a 300,000 square mile area

I don't know where you found these numbers :?

To calculate the 'range' (radius) in line-of-sight from such a platform, try this good approximation:

sqr(13 * altitude)

For instance, 15,000ft altitude (4,500 m) gives a ground diameter of about 480km (300 miles). The ground area would be: Pi * r² = 180,000km² or 70,000 sq miles.
A more realistic 20 km altitude gives a ground diameter of more than 1,000km. Note that the 'range' is much more from (relay)platform to platform.

A network of tethered platforms, even if it was technically possible, would be a huge hazard for air traffic.
I think you were over-enthusiastic here

 

[scottb50]

I was talking about a LTA that uses Helium cooling and heating and electric motors for mobility and station keeping.

There is no reason that the LTA cannot be unmanned. In fact, an LTA that can stay aloft for months at a time makes for a strong case for it being unmanned.

I was thinking a crew to maintain the communication gear, not the aircraft.

 

[PistolPete037]

I was talking about a LTA that uses Helium cooling and heating and electric motors for mobility and station keeping.

There is no reason that the LTA cannot be unmanned. In fact, an LTA that can stay aloft for months at a time makes for a strong case for it being unmanned.

I was thinking a crew to maintain the communication gear, not the aircraft.

When Arthur C. Clark first proposed the idea for the geosynchronous communications satellite, he included a pressurized compartment for the crew that would be furiously busy replacing the thousands of vacuum tubes on the station...

To quote the redoubtable Dr. Emmet Brown "You're not thinking fourth-dimensionally, Marty!"

 

[neilsox]

Lots of good posts. Unmanned is likely practical now. A tether to the ground at 200 mile intervals would, I agree, be a considerable problem for air traffic. I should have revised my post, as 200 miles is about the spacing for 15,000 feet, somewhat less, if there are lots of steep hills. Yes 20,000 feet tethered is practical, if we have CNT with great specs to reduce the weight of the tether, and the craft, or we are willing to risk a broken tether.
The 300,000 square miles was for free flying at 65,000 feet and may be pessimistic if steep hills are rare.
The 200 miles per hour wind speed was suggested at http://www.skywindpower.com Likely they did cherry pick to make their system seem more probable. At the NOAA site I did find 60 knot winds at 38,000 feet to 41,000 feet on July 14, 2010 at 17UTC. I did not figure out where, but I understand high altitude winds are stronger at high latitudes. Neil

 

[orionrider]

A fast wind at that altitude is not much of a problem, because there is a very low atmospheric pressure. The vehicle would also be flying much faster. If it is capable of 50kts at ground level, it will easily fly 150kts up there.

Remember the pressure is very low at 65,000ft, there are not many air molecules to push there.

To illustrate the effect of low pressure on wind effects: if you were standing on Mars you would hardly feel a 100MPH wind.