Getting VLS - Minimum Selected Speed

[cgodinho]

Hello

I'm trying to get the VLS and the formula is: VLS = VS * 1.3 where VS is the stall speed.

I see the offsets 0538, 0540, 0548, 0550 but the explanation in the FSUIPC documentation is not very clear.

For instance 0540 - Design speed VS1 (stall speed clean), ft/sec

I tried to get some information here in the fórum but don't find any

Ok flaps up, but ft/sec ???? that's one of my doubts

I check by FSInterrogate the 0538, 0540 offsets (VS0,VS1) and I get this values:

VS0 = 194.12639

VS1 = 261.64862

I get VS0 value but without flapsall the other values has no meaning.

So can anyone elucidate me about this offsets (the meaning of) , and if it possible to get VLS speed by FSUIPC.

Thank's in advance

Best regards

Carlos Godinho

[Pete Dowson]

I see the offsets 0538, 0540, 0548, 0550 but the explanation in the FSUIPC documentation is not very clear.

For instance 0540 - Design speed VS1 (stall speed clean), ft/sec

The documentation simply reproduces what the Microsoft SDK says for the same variable. I have never used those so I've no idea whether Microsoft are mistaken or not. They have been consistent throughout the life of FS, and they are documented as ft/sec in the latest SimConnect SDK for both FSX and ESP, so I really do think they are correct.

You can easily check. For the specific aircraft the speeds are given in the Aircraft.CFG file. For example, the FS9 737-400:

[Reference Speeds]

flaps_up_stall_speed = 142.0 //Knots True (KTAS)

full_flaps_stall_speed = 113.0 //Knots True (KTAS)

cruise_speed = 477.0 //Knots True (KTAS)

max_mach = 0.82

max_indicated_speed = 340 //Red line (KIAS)

So for this one, VS1 is 142, VS0 is 113, VC is 477. Max Mach is in another offset I think.

Ok flaps up, but ft/sec ???? that's one of my doubts

Why? Are the values inconsistent with that?

I check by FSInterrogate the 0538, 0540 offsets (VS0,VS1) and I get this values:

VS0 = 194.12639

VS1 = 261.64862

I get VS0 value but without flapsall the other values has no meaning.

194.12639 ft/sec = 115 knots

261.64862 ft/sec = 155 knots

Those seem reasonable for an airliner. What aircraft is this? Have you checked the Aircraft.CFG file, where they are defined?

So can anyone elucidate me about this offsets (the meaning of) , and if it possible to get VLS speed by FSUIPC.

I've never heard of VLS before now, and there's no sign of it in FS, nor can I find any references to it in technical aviation books. Can you elucidate?

Regards

Pete

[cgodinho]

Hello, again ...

Well , by definition "VLS" is the minimum selectable speed providing appropriate margin to the stall speed. The guidance computer prevents the aircraft from flying below this speed. At least in Airbus aircrafts (in this case A330-200 PSS)

This was the light ...

194.12639 ft/sec = 115 knots

261.64862 ft/sec = 155 knots

Of course : ((194.12639*0.3048)*3600) / 1852 = 115.0167 knots and this is the VS speed (Stall speed)

It has the same value in the reference speeds section in aircraft.cfg that I already knew

[Reference Speeds]

flaps_up_stall_speed = 155//Knots True (KTAS)

full_flaps_stall_speed = 115 //Knots True (KTAS)

cruise_speed = 460 //Knots True (KTAS)

max_mach = 0.82

max_indicated_speed = 350 //Red line (KIAS)

My confusion was ft/sec, because i'm used this values in Knots

Thank you very much for enlighten me.

Best regards

Carlos Godinho