Arial refueling racetrack

davidbernard · Post by **davidbernard** » 16 Mar 2009, 15:04

Hi,

Question for you flightplan designers. I'm working on a few arial refueling racetrack patterns. Say I want the tanker to fly as in the attached image, will this example flightplan do?

AC#01,XXX,70%,24Hr,IFR,08:00,TNG09:00,240,F,11,AR01,09:04,TNG10:00,240,F,11,AR02,10:04,TNG10:19,240,F,11,AR03,10:23,TNG11:23,240,F,11,AR04,
11:27,TNG11:42,240,F,11,AR01,11:46,TNG12:46,240,F,11,AR02,12:50,TNG13:05,240,F,11,AR03,13:09,TNG14:09,240,F,11,AR04,14:13,15:13,240,F,11,ABCD

Is it correct to make the afcads for the racetrack like this:

Airport alt. 24000 ft, runway length 4 ft, width 4 ft; surface 'water', pattern alt. 1000 ft.

Thanks for your feedback!

Regards,

David

Firebird · Post by **Firebird** » 16 Mar 2009, 15:25

Hi David,
I have a feeling that there are a couple of obstacles, but somebody with more detailed knowledge on the subject may be able to provide concrete answers.

I think that a TNG leg following a TNG leg can cause unpredictable results.
I also thing that there is a max height restriction on the height of an airfield, not too sure about this one.
One thing I have come across is that there is a height difference restriction between the departure airfield and the arrival airfield, its less than 2500', can't remember the exact height. So if an aircraft leaves the Refuelling area it will disappear on approach.

I know that these are all a bit vague but somebody will come along with hard facts, or will tell me that I am idiot

.

Greg · Post by **Greg** » 16 Mar 2009, 15:49

Firebird wrote: One thing I have come across is that there is a height difference restriction between the departure airfield and the arrival airfield, its less than 2500', can't remember the exact height. So if an aircraft leaves the Refuelling area it will disappear on approach.

You're right Steve. It's 1700' to be exact. The aircraft will actually "crash" in mid-air on the way back when it passes 1700' lower than the refueling waypoint.

Greg

Ford Friendly · Post by **Ford Friendly** » 16 Mar 2009, 16:07

This comment does directly answer the question posed, but might be of interest.-----------
Something that is a recent development for FSX, at least, is that the HeliTraffic2009 addon has figured out a way to do "circular" patterns without either landings or takeoffs.

I'm not sure if that is because of something FSX-specific or not and how they do it hasn't been released/described publicly.

mikewmac · Post by **mikewmac** » 16 Mar 2009, 16:15

David,

As Steve stated above with FS9 successive TNG's at multiple airport waypoints do not work reliably and I have found that it is most reliable and reproducible to limit flightplans to including TNG's at just one airport waypoint at 1700 feet AGL or less.

The acceptable altitude difference between a departure waypoint and arrival airport that Steve was trying to remember is 1700 feet. If your tanker does happen to make it around your racetrack pattern successfully and departs your AR04 airport waypoint for your ABCD airport it will disappear after it has descended ~1700 feet from FL240.

In order for your tanker to have any chance of returning to airport ABCD successfully you would have to have airport waypoints at 1700 foot altitude intervals from FL240 down to the elevaton of airport ABCD, which would total 14 additional waypoints. Obviously this is not practical and even if you had them all, it is not certain that your tankers would always if ever return to airport ABCD successfully due to the large number of successive TNG's involved.

Sorry,

Mike

davidbernard · Post by **davidbernard** » 16 Mar 2009, 16:57

Learning every day

Does this 1700' limit only apply if the departure and the arrival airport are in the same AI zone?

David

Greg · Post by **Greg** » 16 Mar 2009, 17:36

In the same AI zone, but also if you want to follow the flight (fly along or with TVB for example) in which case the AI zone moves with your tanker.

Greg