AOA. How do you adjust Angle of attack Indexer?

[alexis99 124]

Does anyone know how to adjust the figures for the AOA indexer in the data.ini?

I have a feeling that for some aircraft, the expected AOA is too high. So when you slow down enough to get the AOA on centre circle, the aircraft is buffeting rather strongly. It seems like you are ready to stall.

Consequently, you land faster than the AOA would like and get the red down arrow.

I've been ignoring the AOA since year dot, but I'm thinking that it just needs adjusting. So how do you aircraft builders work out your AOA figures?

 

[+Cliff7600 1,148]

1 hour ago, alexis99 said:

So how do you aircraft builders work out your AOA figures?

 

I'm not an aircraft builder, but I did some editing on the AOA lights in the cockpit ini file.

By testing, using the landing speed and the rate of descent -> the "on speed" light should work first.
Then defining margins I want for the "low" and "fast" lights, testing from other cockpit files values.

Maybe the glide slope indicator could be useful for the "on speed" light value.

Or...
You could just testing by adding/substracting 1 degree for all values, and so on...
And testing - testing of course !

[alexis99 124]

Are those units in the cockpit.ini for AOA lights actually degrees?

Brilliant. Thank you.

 

[+Cliff7600 1,148]

Yes it's degrees

What aircraft are you editing ?

[alexis99 124]

Sorry, but that's a very difficult question. I'm a flitter. I've been flitting between F/A-18, F-14, A-6A, A-7E, F-8E, F-15A all week. Even I can't remember where I might have noticed a problem.

I've upped my game to make sure I fly all way points, no jumping, so that I burn fuel correctly and arrive at base with a correct weight for placing the fpm where it should be on deck or on the tarmac.

A-7E was a bit of a problem because it carries lots of fuel and only sips at it, so I dropped to 50% fuel and am returning with a decent amount to land by the book.

I was just thinking that if I noticed a buffet when all the other ducks were in a row, then maybe the AOA indexer needed a little help.

I'll let you know which aircraft I adjust, if I do.

Thanks

 

 

[alexis99 124]

A-7E Corsair II.

I'm giving it 75% fuel for the mission because it uses fuel sparingly, and I can carry 24x500 lb bombs.

I'm returning with two sidewinders and Transfer tanks are nearly to zero, with Main full. That should be around 50% fuel, or less.

Natops says I should be landing at 132 knots. I'm coming in at 144, with the pipper on deck ahead of the wires.

If I slow to 140, the pipper is going to leave the HUD and I'm already buffeting a bit. So I stay around 144. AOA shows red arrow. I'm too fast

So the flight model is not perfectly aligned with Natops, and I'm not going to get the AOA indexer liking what I'm doing.

But I'm thinking that I should drop the AOA requirement so that I get a yellow circle at 144. Or maybe it's the early buffet that is wrong???

[alexis99 124]

I worked on the F-8E 66 Crusader. Look what it's got. Three entries for AOA INDEXER

[AoAIndexerSlow]
Type=ANGLE_OF_ATTACK_INDEXER
NodeName=indexer_slow
MovementType=LIGHT
//Slow (13.75 - 30.00)
Set[01].Value=7.48
Set[02].Value=35.25

[AoAIndexerOnSpeed]
Type=ANGLE_OF_ATTACK_INDEXER
NodeName=indexer_on_speed
MovementType=LIGHT
//OnSpeed (12.25 - 14.25)
Set[01].Value=6.33
Set[02].Value=7.86

[AoAIndexerFast]
Type=ANGLE_OF_ATTACK_INDEXER
NodeName=indexer_fast
MovementType=LIGHT
//Fast (0.0 - 12.75)
Set[01].Value=-5.00
Set[02].Value=6.71

In each section there's a struck out entry of the AOA that is being emulated, and some other figures whose units are unknown. Those unknown units are therefore the ones I should adjust.

The F-8E has an approach speed of around 134-145 kts. The AOA prefers me to be at the lower end, but that's where I'm buffeting. Main tank is still full, only transfers used, so I should be at the higher end.

To fix this, I needed to change the values of the OnSpeed and Fast Indexers. I experimented and adjusted the red values as follows

[AoAIndexerOnSpeed]
Set[01].Value=5.00
Set[02].Value=7.86

[AoAIndexerFast]
Set[01].Value=-5.00
Set[02].Value=5.30

This gets me an approach speed of around 142 Kts, with the fpm on the tarmac, but still within the HUD glass, and the Indexer showing the yellow circle. No buffeting, nice smooth touchdown.