Angle of Attack parameter 11BE

[anthonyleaver]

Dear Peter,

Has the range of Parameter 11BE 'Angle of attack' changed with FSX? With the previous versions of FS it was ranged 0 to 32767, now it appears to be divided by 100.

Very best regards

Tony

[Pete Dowson]

Has the range of Parameter 11BE 'Angle of attack' changed with FSX? With the previous versions of FS it was ranged 0 to 32767, now it appears to be divided by 100.

Really? As far as I can see it is completely different, or should be. I have it down in my Offset Status list as "?" and shaded yellow, meaning needs checking.

I'm afraid for these things I am completely dependent upon feedback from someone who knows these things. You are the first to come back, so please advise me.

In FS2004 and before the value I got was:

Angle of Attack. This is actually a relative value, giving in %*32767 the difference between the current AofA and the maximum angle of attack for the current aircraft. For a relative measure of AofA calculate 100-(100*#/32767), where # is this number.

In other words it appears that it was an inverse value -- getting smaller as the angle got bigger, with 0 = 100% of maximum, whatever maximum is, and 32767 being 0%

The only value I can get from SimConnect is an actual Angle in radians. Currently all I am doing with that is multiplying it by 100.0. So this value is going to go from 0 for 0% (instead of 32767 for 0%) to some value probably around 100 or so for 100%.

I need to know how to convert it to something reasonably compatible to what we had before, but how do I know the max angle of attack? That will vary from aircraft to aircraft. How can I compute it from what I have?

For the time being I could do something like this, perhaps: assume 1 radian for the max angle of attack, just for convenience, then convert the value thus:

(1.0 - actual angle) * 32767

What do you think? Should this be allowed to go negative? Can you advise please?

Regards

Pete

[anthonyleaver]

Dear Peter,

Thank you for replying to my post. I am using the angle of attack on my F-4 Phantom sim for the indexer lights and an angle of attack guage.

Reading the Phantom aircrew manual it says the the Phantom AOA guage is scaled 0 to 30 in arbitrary units which is equivalent to -10 to +40 angular degrees of rotation of the AOA probe.

I am no expert in this but previously the following worked well for me and gave me pleasing results but may not be absolutely correct.

-10 angular = 32767 (11BE value)

+40 angular = 8193 (11BE value)

Please let me know if you would like me to experiment further.

Best regards

Tony

[Pete Dowson]

I am no expert in this but previously the following worked well for me and gave me pleasing results but may not be absolutely correct.

-10 angular = 32767 (11BE value)

+40 angular = 8193 (11BE value)

Please let me know if you would like me to experiment further.

And what are you seeing in 11BE for the same aircraft asttitudes that give you these figures? I need to see how to make FSX give similar resluts ot fS9 but I can't see how at present.

I'll do some experiments with default aircraft attitudes, comparing FS9 and FSX. I should be able to derive some sort of useful conversion.

Regards

Pete

[anthonyleaver]

Dear Peter,

I have compared 11BE with FS2004 & FSX with the aircraft on the runway and repeatedly with the aircraft flying at 200 knots at a level attitude,

On runway FS2004 = 32767

On runway FSX = 314

200 knts & Level FS2004 = 24000 Avg

200 knts & Level FSX = 233 Avg

I hope this is useful

Best regards

Tony

[Pete Dowson]

Dear Peter,

I have compared 11BE with FS2004 & FSX with the aircraft on the runway and repeatedly with the aircraft flying at 200 knots at a level attitude

The attitude as shown on the AI would have been useful, as I don't know what sort of way your aircraft sits on the runway or cruises 'level'. And the wing itself will usually be set for a small AoA even with the fuselage "level".

On runway FS2004 = 32767

On runway FSX = 314

200 knts & Level FS2004 = 24000 Avg

200 knts & Level FSX = 233 Avg

I hope this is useful

According to the docs for 11BE, 32767 means 0 AoA, and 24000 means 27% of maximum AoA. So, it seems to me that the FSX figures should be going UP as the FS9 figures go DOWN.

If the AoA being provided by SimConnect for FSX really is in Radians, like it says, and I am multiplying by 100, as I am, the results you show are:

3.14 radians and 2.33 radians, respectively

These are rather large for AoAs. I think they must be measuring not the actual AoA but the incidence of the airflow on the wing, 180% opposite. This would explain the 3.14 (probably 3.142otherwise known as PI). PI radians = 180 degrees.

I'll do some checking on various aircraft types. Meanwhile, what is the maximum AoA you can get without stalling?

Regards

Pete

[anthonyleaver]

Dear Peter,

keeping the arcraft level and closing throttle the stall warning in FSX comes on when 11BE reaches 60, If I pull the stick fully back to attempt to maintain level flight I can get 11BE down to 0.

Regards

Tony

[Pete Dowson]

Dear Peter,

keeping the arcraft level and closing throttle the stall warning in FSX comes on when 11BE reaches 60, If I pull the stick fully back to attempt to maintain level flight I can get 11BE down to 0.

I've been trying to analyse what the actual value is.

I now think the explanation in my offsets list isn't quite correct. Or at least it isn't as accurate as it might be.

The values appears to be an AofA INDICATOR angle value, in FS degree units - that is with 360 degrees represented by 65536.

The value 32767 would then represent 180 degrees, which must represent the indicator being "flat", or reading 0.0 (taking the Boeing AofA gauge as an example).

This would also accord with your estimate of the FSX value being a factor of about 100 out. See here:

In FSX at present 11BE is giving (Angle in radians x 100).

Call this "N". To convert this to FS angle units:

First (N/100 x 180/PI) gets it into degrees

then x 65536 / 360 gets it into FS units.

Simplifying:

(N x 180 x 65536) / (PI x 100 x 360)

gives N x 104.3.

SoI'll proceed on this basis. Download 4.115 from the FSX Downloads announcement above when I get it there (probably later today) and try that.

Regards

Pete

[anthonyleaver]

Dear Peter,

I have tried FSUIPC 4.115 and the Angle of attack parameter now works as it did before in FS2004. I now have a working AoA guage again.

Thanks very much for your work.

Best regards

Tony

[Pete Dowson]

Dear Peter,

I have tried FSUIPC 4.115 and the Angle of attack parameter now works as it did before in FS2004. I now have a working AoA guage again.

Good. Thanks for confirming.

Regards

Pete