[Cumulus] Some Cumulus experiences

[Hendrik Hoeth]

Hi,

Thus spake Eggert Ehmke (eggert.ehmke at berlin.de):

> Hardware: it is important to have the internal battery loaded when starting a 
> task. When connected to external battery with empty internal battery, it 
> starts charging and is not usable in this state. This seems logical and I just 
> ignored the fact. So my first competition day had to be done without Cumulus 
> :-( The LX20 did not show me a restricted area in advance, so I earned some 
> penalty points.

Hmmm, that's interesting. I do charge my N810 before flight, but mostly
because I don't want to drain more from my glider's battery than
necessary. Having said that, I have flown with the N810 partially
charged and it was perfectly usable while charging in flight. What's the
setup you are using?

I use a cheap aftermarket charger cable that has a DC-DC converter and
the small Nokia plug, and connected that to my 12V board system. The
cable is routed through the panel, so I can plug it into the N810:
http://www.linta.de/~hoeth/img_8871_small.jpg
(the USB cable in the picture goes to a USB-serial adapter on the
Cambridge.)

> Next day, I had the N810 loaded and it worked fine for a 5:30 hours flight, 
> with external battery connected. We had area tasks with 40 km radius for two 
> turning points. Unfortunately, the area task setting is a general setting, so 
> also the final destination was regarded as turning point with 40 km radius. 
> When I was on my final glide, 40 km ahead of the destination Cumulus told me, 
> the target area was reached and did not do any more glide path calculations.
> 
> The airspace warning worked very well, no penalty this time! :-)
> 
> I think we need area setting not as a general configuration, but for each turn 
> point separately. This would allow to give the destination point (that must 
> not be the airport) a radius of zero or 500m, while the other turn points are 
> handled as defined by the competition.

I agree, and we also need support for start/finish lines. I've tried
various work-arounds so far; this might give you some ideas what to do
on your next competition flight:

  - To emulate a start/finish line I've set the sector angle to 180
    degrees and the radius to half the line's length. Like this at least
    I know when and where I start or finish. Running over a start line
    without knowing where it is makes me uncomfortable. Disadvantage:
    When you need to turn a standard 90 degree sector, you don't know
    when you're in it. That's why I stopped using this technique.

  - For area tasks I tried setting standard sectors or small cylinders,
    whatever is used for the start/finish (if it's not a line), and then
    during flight I watch the numeric distance to the turnpoint to know
    how far into the area I am. Switch waypoints manually. Disadvantage:
    If you only want to touch the area on one side, it's hard to know
    how far off the course line you need to aim without the area plotted
    on the map. Makes for really uggly guesswork, and makes planning the
    finish just over the minimum task time even more difficult.

  - With the areas set to your 40 km, you can pick the finish point from
    the waypoint list, i.e. not from the points of the task. This will
    cancel the task and provides you with final glide information to the
    finish. Disadvantage: If they use a control point 5 km from the
    actual finish as last turnpoint (e.g. to line the incoming gliders
    up with the runway direction), all your final-glide-around-turnpoint
    calculation (which by the way works great -- thanks Axel!!!!) goes
    bust. Been there, screwed up a final glide, had to scratch for 15
    minutes just to make it back home.

  - You could probably edit your task in flight and change the radius. I
    don't recommend this and the only time I've ever changed a task in
    flight was during a competition when the comp director gave us a
    completely new task after we had already launched -- with the whole
    gaggle circling in two thermals in the start cylinder. Ouch! I
    actually left the cylinder to edit the points, but it still sucked.

One more observation I made when I flew in the Northerns competition
last week is that the task editing window takes forever to open. I
didn't time it, but I'd say it's takes at least 10 seconds. Any idea
what keeps Cumulus that busy?

Cheers,

    Hendrik

-- 
A man without a dream in his heart already has one foot in the grave.