cross channel flight attempt

[Tom]

Hi Brian,

That's great news. There is however another issue. The current firmware version uses the air pressure for altitude hold. Perhaps this is not a good idea if you want to travel large distances. Maybe the air pressure will be different at the arrival point. If you want I can make a special version which uses GPS altitude for altitude hold.

What do you think?

[brian]

Hi Tom,
That sounds good to me.
Though I wonder/ don't know how much difference/error the pressure readings can cause.
If you think GPS altitude hold would be better I'm happy to go with that.

I was wondering about altitude , ie; When you programme an absolute WP at say 120m -is 120 above sea level or 120 above known ground level at that location ??

Regards.
Brian

[Tom]

Hi Brain,

It is 120 meter above the ground level of the starting position. I'll take a look at the GPS altitude tomorrow.

[brian]

Hi Tom,
Thank you.

Brian

[brian]

Hi Tom,
With the current firmware using atmospheric pressure for altitude hold how many meters per mb.
Eg ;if set at 100m at 1004mb what would it do if the pressure dropped to 996mb ??

Brian

[Tom]

This would be about a 70 meter difference

See this website for a quick calculation: http://www.csgnetwork.com/pressurealtcalc.html

As you see, GPS altitude hold will be necessary

I will prepare you a adapted firmware version. I won't be able to test it myself because the weather has been (and will be) bad all week...

[brian]

Hi Tom,
Yes testing will be the issue - weather bad here also.
That is why I am asking - not that I don't have faith in you - but new would have to be tested.
I will work this out with the existing software.
I will allow for any expected difference based on the (at the time) forecast and by flying a little higher to make room for error.
If I set the altitude a little high all the way and then a couple of descending rel-to instructions at the destination wp.
When does it take a reference reading - at power up !??

What do you think

Brian

[brian]

Tom,
At what stage does the Gluon take servo neutral instructions from the tx.
And or when on autopilot does this matter . Or is it using the bench 'sensor calibration' as a straight and level reference.
Need to know as using two transmitters.

Also looking at the data log the pressure altitude spiked on a couple of occasions just for two frames each time.
It spiked to 5500 but the GPS stayed the same at 120 ish.
What are the GPS speed readings - in what units - they seemed very small.

Brian

[Tom]

Hi Brain,

The altitude reference is taken on the first GPS-lock.

The transmitters-neutral settings are taken on startup. The servo's neutral settings are also taken from the RC-transmitter at startup. So make sure both transmitters have the same channels and trimming.

The GPS speed readings could be in meter per second.

I would still recommend to wait for my change for GPS altitude, it is not a big change... what date are you planning to fly?

[brian]

Hi Tom,
I would have to have it for Thursday morning to load and hopefully get to test in the afternoon.
On the ferry to Wales on Fri .
- Sat to set up the Welsh tx and ferry home.
- Flight Sunday to Enniscorthy where I will land it.

If I write and burn that flight plan on Fri / Sat I assume it remains in the flash until replaced and so will start anytime the Gluon is switched to auto.

Brian