Where does this 60-70 kts rubbish come from?
Err? The Upper Air wind charts?
See post #12 of this thread and you will see that the wind on 4 Jan 10 at FL240 was 75kts (I know because I posted it!). Today, at 12Z 16 Jun 10, it was 45kts at FL240. Having flown for 6 weeks over AFG between FL240 to FL290, I know that the wind varies from 10kts to 75kts. Also, if you want to know how much the wind varies in AFG, and how difficult it is to forecast, ask the C-130J mates about their para-supply drops and the use of PADS. I've seen local winds 180degs out from the forecast in the USV and UGV areas due to topography and thermal effects.
Take a look at this website over a year or so and you will soon pick up the trend...
Constant Pressure Maps
(By the way, you need to select 400hPa for FL240 and the SE Asia chart).
On the endurance argument the LEMV needs fuel to stay up - If you run out of fuel then you go down - simples! To stay at "max chat" (70kts) then you run out of fuel fast and your 3 week endurance reduces to less than 3 days!
This is exactly what the US Navy found out when they tried to make lighter-than-air work last time this idea was "dreamt up", this time for maritime surveillance.
"Snake Oil", I say again "Snake Oil"...Warning!
LJ
PS. Here's a video on PADS -
YouTube - WatchBFBSReports's Channel