You're welcome Sparks, feel free to ask for any other tests:

GW 179t F20 FL050

GW 179t F20 FL100

GW 396t F20 FL050

GW 396t F20 FL100

Edited December 5, 20205 yr by jcomm

4 hours ago, jcomm said:

You're welcome Sparks, feel free to ask for any other tests:

GW 179t F20 FL050

GW 179t F20 FL100

GW 396t F20 FL050

GW 396t F20 FL100

Here's where I got to with those

179t, 0=179
179t, 1=176
179t, 5=165
179t, 10=151
179t, 20=124
179t, 30=118
250t, 0=199
250t, 1=196
250t, 5=185
250t, 10=171
250t, 20=145
250t, 30=141
396t, 0=241
396t, 1=238
396t, 5=227
396t, 10=213
396t, 20=191
396t, 30=190

using

local weight_factor = B747_rescale(179000.0, -3, 396000.0, 59.0simDR_acf_weight_total_kg)
    local load_factor = B747_rescale(179000.0, 0, 396000.0, 10.0,simDR_acf_weight_total_kg)
    local flap_Vmc      = 0
    if simDR_wing_flap1_deg[0]<20 then
      flap_Vmc      =B747_rescale(0.0, 182.0, 20.0, 127.0+(load_factor/2), simDR_wing_flap1_deg[0])
    else
      flap_Vmc      =B747_rescale(20.0, 127.0+(load_factor/2), 30.0, 121.0+load_factor, simDR_wing_flap1_deg[0])
    end
    B747DR_airspeed_Vmc = flap_Vmc + weight_factor

B747_rescale is less scarier than it looks, just takes an input, an input range and spits it into an output, for example

flap_Vmc      =B747_rescale(0.0, 182.0, 20.0, 127.0, simDR_wing_flap1_deg[0])

flap_Vmc equals 182 if flaps are 0, 127 if flaps are 20, and in that range when flaps are between 0 and 20

hopefully nothing too far out still, e.g. flaps 20 at 396t are coming in at 191 instead of your 192 - don't think anyone will mind that, hopefully the others are similarly close.

Edited December 5, 20205 yr by mSparks

Wow ! That's Great Work!!! @mSparks !  Congratulations and thank you for your "mind investment" in this project.

I will test all of the other flap settings latter today. Will paste it here without pictures - just the numbers to make it easier to compare with your figures. Please just let me know at what altitude and if you're using ISA or any other weather parameters, and if you test with gear up for the higher flap settings, but from the values you pasted above I think you've nailed it !!!

In the 744 PFD the flap detent speeds are displayed bellow 20k feet after initial flap retraction.

P.S.: There's a sintax error in the first call to "B747_rescale" which for sure you corrected after pasting the code here 🙂 - the last actual parameter lacks a comma before it ( ? )

P.P.S: LR should hire you !

Here you go mSparks:

 

All tests @ 10k feet, gear down for F25/30:

179t, 0=179 ----- 179   
179t, 1=176 ----- 166
179t, 5=165 ----- 170
179t, 10=151----- 137
179t, 20=124----- 127
179t, 25=???----- 121
179t, 30=118----- 118
250t, 0=199 ----- 223
250t, 1=196 ----- 187
250t, 5=185 ----- 172
250t, 10=171----- 159
250t, 20=145----- 150 (149.5)
250t, 25=???----- 142
250t, 30=141----- 139
396t, 0=241 ----- 240 (239.5)
396t, 1=238 ----- 227
396t, 5=227 ----- 212 (211.5)
396t, 10=213----- 199
396t, 20=191----- 189
396t, 25=???----- 182 (181.5)
396t, 30=190----- 179 had to use manual throttle due to flap relief limitations, max 180knot for f30

 

Edited December 6, 20205 yr by jcomm
typos and completion

Hi, I cannot enter the airport in the POS page of the FMS, it keeps telling me Key is Not Active.

How can I solve this?

Im on iMac, latest X-Plane installed

 

Thanks

 

Tony

7 hours ago, jcomm said:

the last actual parameter lacks a comma before it ( ? )

yeah, I was testing in eclipse ldt using different variable names and changing them in the paste into here, broke it into its own function to avoid that

another step closer (not really the proper way of doing it, but an OK estimator)

function setVmc(weight,flaps)

    local weight_factor =  B747_rescale(179000.0, 0, 396000.0, 61.0, weight) 
    local noflap_weight_factor = B747_rescale(0.0, 0, 27.0, 61, weight_factor)  
    local flap_Vmc      = 0
    if flaps<1 then
      flap_Vmc      =B747_rescale(0.0, (179), 1.0, 166, flaps) + noflap_weight_factor --13/1
    elseif flaps<10 then
      flap_Vmc      =B747_rescale(1.0, 166, 10.0, 137, flaps) + weight_factor --3/1
    else
      flap_Vmc      =B747_rescale(10.0, 137, 30.0, 118, flaps) + weight_factor --0.95/1
    end
    B747DR_airspeed_Vmc = flap_Vmc 
    print(" " ..weight/1000 .. "t, " .. flaps .. "=" .. math.floor(B747DR_airspeed_Vmc))
end

results

 179t, 0=179 ---- 179
 179t, 1=166 ---- 166
 179t, 5=153 ---- 170
 179t, 10=137 --- 137
 179t, 20=127 --- 127
 179t, 25=122 --- 121
 179t, 30=118 --- 118
 200t, 0=192  
 200t, 1=171
 200t, 5=159
 200t, 10=142
 200t, 20=133
 200t, 25=128
 200t, 30=123
 250t, 0=224 ---- 223
 250t, 1=185 ---- 187
 250t, 5=173 ---- 172
 250t, 10=156 --- 159
 250t, 20=147 --- 150
 250t, 25=142 --- 142
 250t, 30=137 --- 139
 300t, 0=240
 300t, 1=200 
 300t, 5=187
 300t, 10=171
 300t, 20=161
 300t, 25=156
 300t, 30=152
 396t, 0=240 ---- 240
 396t, 1=227 ---- 227
 396t, 5=214 ---- 212
 396t, 10=198 --- 199
 396t, 20=188 --- 189
 396t, 25=183 --- 182
 396t, 30=179 --- 179

Edited December 6, 20205 yr by mSparks

5 hours ago, mSparks said:

 

 Congratulations mSparks! Superb match with your formulas!!!

 179t, 0=179 ---- 179
 179t, 1=166 ---- 166
 179t, 5=153 ---- 170
 179t, 10=137 --- 137
 179t, 20=127 --- 127
 179t, 25=122 --- 121
 179t, 30=118 --- 118
 200t, 0=192  --- 183.5
 200t, 1=171  --- 171
 200t, 5=159  --- 156
 200t, 10=142 --- 142.5
 200t, 20=133 --- 134
 200t, 25=128 --- 126
 200t, 30=123 --- 123
 250t, 0=224 ---- 200
 250t, 1=185 ---- 187
 250t, 5=173 ---- 172
 250t, 10=156 --- 159
 250t, 20=147 --- 150
 250t, 25=142 --- 142
 250t, 30=137 --- 139
 300t, 0=240  --- 214
 300t, 1=200  --- 200
 300t, 5=187  --- 186
 300t, 10=171 --- 172.5
 300t, 20=161 --- 164
 300t, 25=156 --- 156
 300t, 30=152 --- 152.5
 396t, 0=240 ---- 240
 396t, 1=227 ---- 227
 396t, 5=214 ---- 212
 396t, 10=198 --- 199
 396t, 20=188 --- 189
 396t, 25=183 --- 182
 396t, 30=179 --- 179

 

Edited December 6, 20205 yr by jcomm

179t, 0=179

200t, 0=183.5

250t, 0=223

300t, 0=214

396t, 0=240

Thats a strange cluster of numbers - hth is 300t a lower Vmc than 250t and ~400t; surely Vmc only increases with weight, and 10kts is surely to big a difference to be a reading error?

Edited December 6, 20205 yr by mSparks

Well spotted Sparks...

Might have been a copy error - will test again and report back. 

Ok - my typo 😕 sry:

250t, 0= 200 ( 199.5)

300t, 0= 214

Edited December 6, 20205 yr by jcomm

2 hours ago, jcomm said:

Well spotted Sparks...

Might have been a copy error - will test again and report back. 

Ok - my typo 😕 sry:

250t, 0= 200 ( 199.5)

300t, 0= 214

nice one. That should fit nicely. I did a quick flight test with the ones I had and zero flaps was definitely way to high.

Time next to run some actual flight tests and see what she actually stalls at, pretty sure stalls are actually kicking in way to early atm.

Just to check my understanding is correct: Vmc is constant in a bank and above vmc you should be able to hold a max bank turn without stalling.

Edited December 7, 20205 yr by mSparks

Affirm.

The Stick-Shaker band comes bellow it, and that one does vary with the "Gs"...

There's also the top amber band, indicating max maneuvering speed, and above it the "VMO band" in red dots like the lower stick shaker one. 

But yes, big problem now will be to make the XP11 744 aerodiynamically match those values ...

I don't dislike the default XP 744 behaviour, although my closest match is actually the PSX thing, and the extraordinary ( for its time ) 744 that made part of the "Airline Simulator 2" fleet, but two aspects where PSX and XP differ dramatically in terms of aerodynamics are the thrust-pitch coupling, very intense in PSX and just slightly felt, with lot's of lag in XP, the reason why the real thing is never manually flown with auto-throttle set.

The other is pitch stability ( stick-fixed I guess ? But just asked at the Aerowinx forum 🙂 ).

Edited December 7, 20205 yr by jcomm

34 minutes ago, jcomm said:

There's also the top amber band, indicating max maneuvering speed, and above it the "VMO band" in red dots like the lower stick shaker one. 

Those thankfully have tables already in.

This is about the 4th visit to Vmc, normally whoever is complaining gives up when they find there is no tables for Vmc, but this time I had your offer to virtual flight test in hand.

Looking forward to measuring the actual stall characteristics tbh, wasnt much point before knowing what they should look like, Then I should have a reason to actually use xps most interesting and valuable tools.

 

21 hours ago, mSparks said:

Just to check my understanding is correct: Vmc is constant in a bank and above vmc you should be able to hold a max bank turn without stalling.

The top of the amber band give you 1.3 G or 40 degree bank manoeuvre capability. (Static)

The top of the red bricks is stick shaker activation which activates above the actual stall with supposedly enough margin to allow recovery before entering the stall. (Moves with G loading)

Good luck.

Edited December 7, 20205 yr by jon b

2 hours ago, jon b said:

40 degree bank manoeuvre capability.

dont think I'm going all the way to 40 degrees. 25 would be nice and pretty sure it cant even manage that atm, but we'll see what the flight tests bring up

 

Overall, this thread at the Aerowinx Forum is very informative on the subject:

 

Stall speed: how is it calculated? (aerowinx.com)

Interesting question raised here on that thread, by Will, a seasoned PSX user and airline captain:

I'm having trouble understanding the difference between minimum maneuvering speed (top of the lower amber band) and flap maneuvering speed. 

Minimum maneuvering speed is based on weight, angle of attack, and airspeed. 

Flap maneuvering speed is based on weight. 

For a given weight, as the AOA increases, the amber band "shortens" because the red band increases, but the green flap maneuvering speed should stay the same.

What I guess I don't get is this: Why isn't the top of the amber band always equal to the lowest visible green flap number? Put another way: why is the flap maneuvering speed usually greater than the minimum maneuvering speed?
 

and Hardy's answer in here: Stall speed: how is it calculated? (aerowinx.com)

If you're up for the technical stuff ( from Boeing ) then skip into: Here

If Math is you beach, then start here instead:  The Maths...

Edited December 8, 20205 yr by jcomm
completion

IbraD and Devinci put together a SmartCopilot config (video above is from early testing)

https://drive.google.com/file/d/1_cTSFsQxB6-0VHDt96tHTVZ7M8yYnn12/view