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Hodge7

Use Of The New Flight Computer In The Soardg8082

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Is there a way of using the new "arrival height" flight computer in the V3 Soar DG for intermediate waypoints of the pilots own choosing. eg If i want to get to a particular point (which is not a waypoint) at a certain height and therefore adjusting my speed to arrive at that height.

Can this be done in a real glider and can it be done in our virtual dg??

I'm thinking that if the ability to insert extra manual waypoints by the pilot for a specific mission was possible it would greatly assist the planning and execution of a mission.

Hodge

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Is there a way of using the new "arrival height" flight computer in the V3 Soar DG for intermediate waypoints

Interesting request - the user interface of the V3 modified 'Cambridge' vario is intentionally kept as simple as possible so the majority of pilots don't have to click anything and the instrument will still do something sensible (although the arrival height will be at max L/D i.e. maccready zero). This conceals a fair amount of complexity in the calculations 'behind the scenes', in particular 'arrival height'.

The basic mechanism available to introduce intermediate waypoints would be to modify the flight plan, i.e. the .PLN file, and place that in the mission folder. This is completely legitimate and doesn't alter the performance or behaviour of the mission in any way, although the GPS will now be pointing you to intermediate waypoints while the mission pointer points you to the next proper task turnpoint.

There are two problems with the V3 version that prevent this at the moment, but both are fixable:

1) the V3 modified Cambridge has a single function that calculates 'distance to go' (and bearing) to be used in the arrival height calculation. This function looks for a mission waypoint *first* and failing that (i.e. you are in free flight) it looks at the next waypoint in the flight plan. I could add a switch that forces the Cambridge to use the flight plan only, or you could temporarily hack your copy of my gauge to *never* use the mission waypoint:

You can kill the code in the two placees where it detects the mission waypoints by adding zeroes:

before:

<Comment><Value>*******************************************************
                    CALCULATE DESTINATION ALT METERS MSL
         **********************************************************************
...snip...
                        (C:POI:SelectedTargetMSLAltitude, meters) d 0 !=
stick a zero on the end i.e. after:
(C:POI:SelectedTargetMSLAltitude, meters) d 0 != 0
and also the same idea here: before:
<Comment><Value>*******************************************************
                    CALCULATE ARRIVAL HEIGHT
         **********************************************************************
... snip...
                        (C:POI:SelectedTargetDistance, meters) 0.001 >
that last line becomes after:
(C:POI:SelectedTargetDistance, meters) 0.001 > 0

2) Gotcha #2 - the waypoint *altitudes* in flight plans are "whatever the user happened to put in when the flight plan was created". By some miracle I did actually edit the USA Nationals flightplan waypoints to be the ground elevations at those points even though the Cambridge isn't using it, but this is usually *not* the case. The arrival height in the Cambridge is *relative* to the height at the waypoint, so you'd have to very careful using other flightplans if you don't check what altitude was put in there (typically it's the flight level).

I'll make an effort to include a switch in V4 and make sure my missions have the right elevations in the flightplan.

Ian

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Sounds great, thanks Ian; I wouldn't trust myself to start changing code, but to clarify my intentions, with this latest mission there are certain places of almost certain lift and that is of course ridges of sufficient height, shape and in conjunction with the wind speed and direction, lift on a given ridge can be estimated before flying a mission.

In the case of US Nationals Day 1 I noticed that with the increased performance of the Soar DG it should be possible to fly direct from the start gate of the mission to the Raystown ridge in one go. But what speed to fly???

In the mission I thermalled before the start gate back to 6800' (which can be seen on the trace), dived and went through the start gate at 5800 at vne and then headed out towards Raystown lake at about 95kts and luckily made the ridge ok. However had I been able to designate a waypoint at the beginning and on top of the ridge (which detemines an AGL about 2300' on the altimeter, then all the way to that point I would be able to optimise my speed.

I would imagine this is done by pilots in real competitions ?

Jeff

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