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Strange anti-noise departure values by CPS-X


Michele Benedetti

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Michele Benedetti

Hi!

I was planning a flight EGLL-TBPB with the original route provided by the plans pack in the download section which is also the official route that concorde used, and CPS-X gave me a time of 109 seconds. Is it right?

Thanks!

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Martin Tornberg

I think that you might want to adjust the NM which dictates how long the reheats will be on.

When you get to the Performance module there is a Noise Reduction Data field where you can choose distance and bank angle to be used on departure. 

Not sure on the correct distance to use but I generally stick with either 3-4 NM which gives me something between 60-75 seconds on reheats depending on TOW. 

3362cae89991452394e361678933ef03.png

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Ray Proudfoot

That's very interesting Martin. I've just departed 09R at EGLL for a flight to GCLP. TOW was 138.8T and temp was 10°C. According to that chart reheats should be on for around 50 secs. I entered 5nm for the noise abatement which resulted in 66 secs for reheats.

With an immediate right turn after take-off the speed got away from me and approached 290kts before the reheats were cancelled by the VFE.

I'm wondering if CPS-X can calculate the optimum time for reheats based on air temp and take-off weight rather than just the user entering an arbitrary distance. 5nm might be fine for a heavy load but it's far too much for a lighter one. I'll speak to Pierre.

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Fraser Gale

I used CPS for the first time the other day and when I cross checked the takeoff performance there was quite a difference from the chart/calculated values to that of CPS. The V speeds were higher by around 6 knots. I reverted to my calculated values. 

The charts in the performance manual were produced by performance planners and were specialised for each condition and departure runway. If specialised charts don't exist in the PM the crew used the generalised charts which I assume is what CPS does. 

I also noticed the the VZRC speed (2 engines) was exceptionally low (189kts gear up) for my weight of 182350kg - this speed would induce a sizeable descent. It should have been around 260kts gear up and over 300kts gear down.

Frazz

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Pierre Chassang

Hi Captains,

The noise reduction procedure seems to be misunderstood.
It doesn't correspond only to the reheat cutting off.
It had to be done even in case of TO without reheat that is the proof of what I mean above.

The reheat was the main source of noise, but not only. Actual liners have to perform noise abatement on many airport.

The Concorde noise reduction is managed in two different parts but linked together.
1- Reheat cutoff time.
2- Thrurst reduction.

The reheat cutoff time is depending of 4 parameters
1- The distance to proctect from brake release (keeping le runway length into account). It depends of the runway end environment (Population density etc). It may be very different from one to others.
2- Airport pressure altitude.
3- Air temperature.
4- TOW.

These parameters and the resulting time are listed into an Air-France Document I own for a certain number of airports (it has more tha 150 pages). I think viewing the Martin's chart, British Airways got one too.

AF has designed an abacus for all airport. CPS-X uses this abacus calculating this time.
As the distance to protect is unknown for most of airport it must be estimated by the Captain.

The thrust reduction is depending of 4 parameters

1- TOW.
2- Pressure altitude.
3- Air temperature.
4- Average bank angle during procedure.

As for Reheat cutoff time AF has designed an abacus which gives TLA usable for all airport.
The N2 is associated to TLA using a scale.

The thurst reduction must be performed either at reheat cutoff time or at 1000 ft the first reached (a residual climb slope of 3% is kept).
CPS-X uses this second abacus calculating the TLA and N2 associated.

I note another difference between AF and BA in the Vzrc calculation:
Frazz says "... I also noticed the the VZRC speed (2 engines) was exceptionally low ...".

Vzrc following the AF FCOM, is for 3 engines instead of 2. This explains the difference of results.

Hope this help

Kind regards

Thrust reduction.pdf

Reheat time abacus.pdf

Vzrc3.pdf

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Ray Proudfoot
5 minutes ago, Pierre Chassang said:

As the distance to protect is unknown for most of airport it must be estimated by the Captain.

And that is the problem. Without the knowledge how do we estimate that distance safely especially with variable TOWs?

Set it too long as I did yesterday (5nm with a TOW of 138.8T) and Concorde is exceeding 290kts before the reheats are cancelled and reduced thrust engaged. Set it too low and reheats are cancelled before a safe altitude is reached. I respectfully suggest the user needs some help with the reheat time especially with lower TOWs.

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Ray Proudfoot
34 minutes ago, Pierre Chassang said:

Don't forget the distance and bank angle can be saved and restored for each runway of each airport when you get a good values...

But what about the TOW Pierre? Isn't that the most important factor? 5nm for a TOW of 140T is very different to a TOW of 190T.

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Pierre Chassang
1 minute ago, Ray Proudfoot said:

But what about the TOW Pierre? Isn't that the most important factor? 5nm for a TOW of 140T is very different to a TOW of 190T.

The CPS-X takes it into account in the calculation.

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Ray Proudfoot
3 minutes ago, Pierre Chassang said:

The CPS-X takes it into account in the calculation.

OK. I'm clearly entering a number far too high. It seems the only way to ensure I don't overspeed after takeoff is to try 4nm for < 140T and perhaps 5 for heavier TOW.

I will also experiment by saving the runway info.

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Ray Proudfoot

I was pitching up so much the climb rate was in excess of 7000fpm.

This is with P3D. It is different to FSX. The aircraft seems to have more power on takeoff than in FSX. I know that may sound strange but having flown it for a few years in one sim it does seem different in P3D.

And that was with a TOW of 138.8T and 51.4T of fuel for a flight from EGLL to GCLP.

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Pierre Chassang

I read on AF documents that for example on a CDG East departure for JFK, the reheats have to be OFF as soon 280 k was reached.
In fact the reheat cut off and the thrust reduction are both noise reduction part but they can be triggered separatly.
On your EGLL to GCLP at low TOW, the reheats could have been cut when reached 250 kts and the thrust reduction after the planned time.

Keep in mind the time set is noise reduction, not necessarily reheat cut off.

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Ray Proudfoot

Thanks Pierre but you'll be aware the noise reduction and reheat cut off are inseparable with the VFE handling that aspect of the flight.

It may be helpful to have a button that can override them. I'll check if a command is available.

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Pierre Chassang

As I noticed the Vzrc is calculated for 3 engines by AF and for 2 engines with BA, If anyone here own the Vzrc2 (2 engines) charts or abacus, I will be happy to implement this calculation into a next build of CPS-X.;)

Thanks

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Martin Tornberg
1 hour ago, Ray Proudfoot said:

Thanks Pierre but you'll be aware the noise reduction and reheat cut off are inseparable with the VFE handling that aspect of the flight.

It may be helpful to have a button that can override them. I'll check if a command is available.

What happens if you disable the engine management option in the FSLABS menu? In that way you should be able to press Shift+F4 for turning off reheats. And then CTRL+5 to set the throttles to the value set on the pedestal previously. And last thing is to press CTRL+F6 to go from TAKE OFF to FLIGHT. 

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Ray Proudfoot
3 minutes ago, Martin Tornberg said:

What happens if you disable the engine management option in the FSLABS menu? In that way you should be able to press Shift+F4 for turning off reheats. And then CTRL+5 to set the throttles to the value set on the pedestal previously. And last thing is to press CTRL+F6 to go from TAKE OFF to FLIGHT. 

Panic probably! :D Too many things for one person to control. I only have two hands. ;)

I did try setting a button command via FSUIPC to CTRL+F4 when pressed and CTRL+F4 again when released to simulate the reheats going off in pairs. But without some fancy programming I couldn't add CTRL+F5 for the TLA.

No matter. I have found that after a few test take-offs the reheats are best coming off around 45-50 secs for a TOW around 140T which equates to 4 miles in CPS-X. I'll try that and the heavier I get I'll slowly increase that setting.

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Pierre Chassang

Ray,

You don't have to increase the distance according to TOW, CPS should calculate the time keeping this parameter into account.

There is an excellent addon to manage this kind of commands, LINDA. I used it some years ago and I will be able to create commands through a simple programming code.

I had create a Concorde profile which openned the start panel automatically and shut off the debow switches. I'll try to found it to share it with you. LINDA is a free utility.

Hope this help.

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Pierre Chassang

Have a look here:

https://www.avsim.com/forums/topic/372388-fsl-concorde-module-version-10/

and here is the script I wrote for VrInsight MCP I , Saitek yoke, 2 Saitek throttle quadrands and Saitek rudder pedals.


-- FSLabs CONCORDE

-- Version 1.0b Pierre Chassang 2012





-- ## System functions ##



function InitVars ()

 VORmode = 1

    -- uncomment to disable display

    AutopilotDisplayBlocked ()



end 



-- ## Autopilot Controls ###############

function CONC_AP1_Toggle ()

  ipc.control(66587,71084)

end



function CONC_AP2_Toggle ()

  ipc.control(66587,71085)

end



function CONC_ATH1_Toggle ()

  ipc.control(66587,71080)

end



function CONC_ATH2_Toggle ()

  ipc.control(66587,71081)

end



function Max_Climb ()

  ipc.control(66587,71074)

end



function IAS_Acq ()

  ipc.control(66587,71062)

end



function IAS_Hld ()

  ipc.control(66587,71061)

end



function Vertical_SPD ()

  ipc.control(66587,71077)

end



function ALT_Acq ()

  ipc.control(66587,71079)

end







function AP_Datum_Pitch_Down ()

  var = ipc.ReadLvar("VC_Datum_AP_Pitch_Sw")

  if var == 20 then

     ipc.WriteLvar("VC_Datum_AP_Pitch_Sw",0)

  end

  ipc.control(66587, 73530)

end



function AP_Datum_Pitch_Neutral ()

    ipc.WriteLvar("VC_Datum_AP_Pitch_Sw",20)

    ipc.control(66587, 73532)

end



 function AP_Datum_Pitch_Up ()

  var = ipc.ReadLvar("VC_Datum_AP_Pitch_Sw")

  if var == 20 then

     ipc.WriteLvar("VC_Datum_AP_Pitch_Sw",40)

  end

  ipc.control(66587, 73531)

end



function AP_Datum_Roll_Left ()

  ipc.control(66587,73525) --vc_Datum_AP_Bank_Sw = 99..98..

end



function AP_Datum_Roll_Neutral ()

  var = ipc.ReadLvar("VC_Datum_AP_Bank_Sw")

  if (var < 100 and var > 50)   then

  ipc.control(66587,73527)

  end

  if (var > 0 and var < 50) then

  ipc.control(66587,73528)

  end

end



function AP_Datum_Roll_Right ()

  ipc.control(66587,73526) --vc_Datum_AP_Bank_Sw = 1..2..

end



function TRK_HDH ()

  ipc.control(66587,71130)

end





-- ## Rotaries Functions ###############

function ALT_plus (a, b, c)

  ipc.control(66587,71136)



end



function ALT_plusfast (a, b, c)

  ipc.control(66587,71136)



end



function ALT_minus (a, b, c)

  ipc.control(66587,71135)



end



function ALT_minusfast (a, b, c)

  ipc.control(66587,71135)



end



function SPD_plus ()

  ipc.control(66587,71095)

end



function SPD_plusfast  ()

  ipc.control(66587,71095)



end



function SPD_minus ()

  ipc.control(66587,71096)



end



function SPD_minusfast ()

  ipc.control(66587,71096)



end



function HDG_plus ()

  ipc.control(66587,71107)

end



function HDG_plusfast ()

  ipc.control(66587,71107)

end



function HDG_minus ()

  ipc.control(66587,71108)

end



function HDG_minusfast ()

  ipc.control(66587,71108)

end



function CRS_left_inc  ()

  ipc.control(66587,71110)

end



function CRS_left_dec  ()

  ipc.control(66587,71109)

end



function CRS_right_inc  ()

  ipc.control(66587,71121)

end



function CRS_right_dec ()

  ipc.control(66587,71122)

end







-- ## Engines start ###############

function Debow_All ()

  ipc.control(66587,71998)

  ipc.sleep(900)

  mouse.move(60,583)  --Engine1

  ipc.sleep(100)

  mouse.click(0)

  mouse.move(122,583) --Engine2

  ipc.sleep(100)

  mouse.click(0)

  mouse.move(181,583) --Engine3

  ipc.sleep(100)

  mouse.click(0)

  mouse.move(237,583) --Engine4

  ipc.sleep(100)

  mouse.click(0)

end



function Mouse_Coord  ()

  x, y = mouse.getpos()

  DspShow("ENG2", x)

  ipc.sleep(1000)

  DspShow("ENG2", y)

end







function ENG2_Start ()

  ipc.control(66587,71998)

  ipc.sleep(800)

  mouse.move(122,496)

  ipc.sleep(1000)

  mouse.click(2) -- démarreur 2

  DspShow("ENG2", "Strt")

end



function ENG3_Start ()

  mouse.move(178,496)

  ipc.sleep(1000)

  mouse.click(2) -- démarreur 3

  DspShow("ENG3", "Strt")

end



function ENG1_Start ()

  ipc.control(66587,71998)

  ipc.sleep(800)

  mouse.move(66,496)

  ipc.sleep(1000)

  mouse.click(2) -- démarreur 1

  DspShow("ENG1", "Strt")

end



function ENG4_Start ()

 mouse.move(236,496)

  ipc.sleep(1000)

  mouse.click(2) -- démarreur 1

 DspShow("ENG4", "Strt")

end



function ENG2_Fuel ()

  ipc.control(66587,75084)

end



function ENG3_Fuel ()

  ipc.control(66587,75086)

end



function ENG1_Fuel ()

  ipc.control(66587,75082)

end



function ENG4_Fuel ()

  ipc.control(66587,75088)



end







-- ## Panels view ###############



function FWD_leg () --Tableau demarrage moteurs

 ipc.control(66587,71998)

end



function Lowerfuel ()

    ipc.control(66506,8009)

end



function Upperfuel ()

    ipc.control(66506,8010)

end



function AirBleed ()

    ipc.control(66506,8012)

end



function Hydraulic ()

    ipc.control(66506,8011)

end



function AC ()

    ipc.control(66506,8007)

end



function DC ()

    ipc.control(66506,8008)

end

-- ## Misc ###############



function Gear ()

    var = ipc.readLvar("vc_GearLever")

 if var == 100 then

    ipc.writeLvar("vc_GearLever",50)

 end

 if var == 50 then

    ipc.control(66080,0)

end

end



function Min_Dec ()

   ipc.control(66587,71370)

end



function Min_Inc ()

   ipc.control(66587,71371)

end



function setAPALT(offset, value)

  Global.buffer = ipc.readUD(0x07D4)/65536*3.28/100

  com.write(dev, string.format("ALT%03d", math.ceil(buffer)),8 )

end



function Chrono_EET_Start  ()

  ipc.control(66587,71513)

  ipc.control(66587,71511)

end



function ENG_Monitor ()



LVarSet= "L:vc_TOmon_Knob"

Mon = ipc.readLvar(LVarSet)



 if Mon == 0 then

    ipc.control(66587,71577)

 else

    ipc.control(66587,71578)

 end

end



function Visor_Motion_Dwn ()

  --ipc.control(71560,0)

  ipc.control(66294,0)

end



function Visor_Motion_Up ()

  --ipc.control(71560,0)

  ipc.control(66295,1)

end



-- ## Radios ###############

function Conc_VOR_rotary_CP_FO_toggle ()



    if ipc.get("VORmode") == 1 then

    ipc.set("VORmode", 2)

    DspShow ("VOR", "FO")

    else ipc.set("VORmode", 1)

    DspShow ("VOR", "CP")

    end

end



function Conc_VOR_inc ()

    if ipc.get("VORmode") == 1 then

    Conc_CP_VOR_inc ()

    elseif ipc.get("VORmode") == 2 then

    Conc_FO_VOR_inc ()

    end

end



function Conc_VOR_dec ()

    if ipc.get("VORmode") == 1 then

    Conc_CP_VOR_dec ()

    elseif ipc.get("VORmode") == 2 then

    Conc_FO_VOR_dec ()

    end

end



function Conc_CP_VOR_inc ()

     var = ipc.readLvar("SSTSIM_VC_NAVRadio_CP_Freq_L_Knob")

     Var = Var + 10

     ipc.writeLvar("SSTSIM_VC_NAVRadio_CP_Freq_L_Knob", var)

end



function Conc_CP_VOR_dec ()

     var = ipc.readLvar("SSTSIM_VC_NAVRadio_CP_Freq_L_Knob")

     Var = Var - 10

     ipc.writeLvar("SSTSIM_VC_NAVRadio_CP_Freq_L_Knob", var)

end

I don't know if it works with P3D.

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Ray Proudfoot

Hi Pierre,

Thanks for that. I have heard of LINDA but never used it. I'm not sure I'm ready to learn it just yet. Given the example in the abacus document you provided was for a noise reduction distance of 4.5nm I'm going to use that for all my flights and see how I get on with it.

Having the option to enter decimals of a nm would be helpful. Say 4.0, 4.5, 5.0 etc. Not 4.1, 4.2 etc.

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Ray Proudfoot
3 minutes ago, Pierre Chassang said:

Done in next release Ray.

Great service Pierre, thanks. :)

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Fraser Gale

I have the VZRC charts, I will get them to you as soon as I get a minute.

 I don't see what the point of having the 3 engine ZRC speed is? V2 is the safe three engine climb out speed and you should ALWAYS be above that or get above that as soon as possible. The 2 engine is the need to know for a double failure on take-off where the procedure was to maintain VZRC  and the altitude reached (even if this was only 50 feet or something) while the flight engineer started dumping fuel as quickly as possible to lower the weight. You had to fly in a straight line without turns and fly with 0 side slip to stay in the air. Eventually once the weight lowered enough you could begin to climb - all this while making sure you didn't exceed the time limitations for contingency rating on the 2 engines you had left, if they failed you were in trouble!

BA crews always practiced double engine failures, and apparently every crew crashed the simulator at least once until they got used to it. Form what I'm told (this could be wrong) AF did not practice double failures which didn't help things on the day of the accident. Maybe this is why they used 3 engine VZRC, I'm not sure.

Frazz

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Fraser Gale

I've just been reading some earlier posts on here about separate reheat and power reduction. This wasn't the case at BA. The two actions always occurred at the same noise time, the engineer had one hand on the reheat switches and the other on the throttle leavers and would be gripping the central consol with his knees to hang on during the change of g force! 

When a specific charts wasn't provided in the performance manual, like the one above, the reduction would occur at 1000ft radio altitude, and another chart within the performance manual gave the N2/TLA for the take-off weight of the day. 

The only power change that would be at different times, would be when no noise abatement was required (Barbados for example) and the reheats would go off at 500ft and the engine rating switches changed to climb at 1000ft, the throttles were left fully forward. 

I understand that AF used a faster initial climb speed and not 250 knots like BA, which must have also required an early nose/visor raise, which BA didn't do till 5000ft or above. The normal call by the handling pilot at 5000ft was "through 5000, increasing speed" then they would call for the nose and visor. 

Frazz

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Fraser Gale

I had sent you the BA chart also. It should be easy enough for you to incorporate in CPS, I wrote my own programme for the take-off calculations a few years ago, although I used the specific data for each runway then included an option for use of the generalised data.  It makes it quite accurate. 

Someone with your experience should manage it easily and quickly.

Frazz

  • Like 2
Link to comment
Michele Benedetti

Hi!

So, in the end, how do I exactly calculate the correct distance value for noise abatement procedure: Pierre said above that it also depends from the SID, what does this mean?

 

Link to comment
Ray Proudfoot
28 minutes ago, Michele Benedetti said:

Hi!

So, in the end, how do I exactly calculate the correct distance value for noise abatement procedure: Pierre said above that it also depends from the SID, what does this mean?

 

Michele,

Some airports like EGLL had specific noise abatement rules for specific runways. 09L/R for example where you were flying over heavily populated areas immediately after take-off. Others like Barbados had none as you were over the ocean almost immediately.

CPS-X takes your TOW into account when calculating reheat time. I suggest you stick to a fixed reheat distance. I'm going to use 4 or 5 miles. Suggest you use the same.

Link to comment
Pierre Chassang

Hi,

An aircraft at takeoff overfliys a part of airport environment which vary depending the departure path.
Some are flown above prairies, lakes, fields and some are flown above speedways, urban areas.

So the distance to trigger the antinoise procedure is variable. It can't be calulated but only estimated in accordance with the terrain overflown.
Furthermore the airport environment evolves over time when new neighborhoods are built. The anti noise procedure then changes.

The main thing to keep in mind is the distance and the corresponding time are thrust reduction, not reheat cut off time.
Even if they can be mingle, it is not alway the case.

The reheat cut off is often performed at a determined altitude or speed.

Link to comment
Michele Benedetti

Hi! 

Thanks both of you, now it's much clearer, but I think I'll go for Ray's way and just stuck 4 nm because it went perfect with that distance during all the flights I've done before

Link to comment
AdrianSmith

Surely reheat only works at 100% throttle setting, so reducing the throttles to the TLA bug will, by default, cancel the reheat; it is just that they will remain armed so next time you command 100% throttle you will get reheat again!?

Link to comment
Ray Proudfoot

I flew EGLL-GCLP again this afternoon and set Noise Reduction Distance to 5 miles. The take-off was to the east with an immediate right turn.

The reheat time of 60s was too long. I'd hit 270kts by the time the reheats were cancelled and throttles were reduced. Trying to pitch up to keep IAS to 250kts is not easy when you're having to turn right through 110°. It's probably easier with a straight ahead departure.

So I think 4 miles is going to be the ideal distance.

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Fraser Gale

Ray, I personally would use 3 or 3.5 miles if you have to put in a distance for the 09s at Heathrow. The runway itself is about 2.25 miles long if I remember correctly and the noise time has to be quite soon due to the proximity of the built up area. 

The 27s give you a but longer so 3.5 to 4 miles for them.

Give it a try and see if you get better results. As long as you get to 1000ft radio and 235 knots you can cut to noise power. 

Frazz

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Ray Proudfoot

Thanks Frazz. Everything happens so quickly when TOW is well below max. This needs practice to perfect. No wonder they had 3 people in the real aircraft! :D

Link to comment
Fraser Gale

Absolutely! That's also why no pilot was permitted to perform a light weight take-off until they had done their final route check (around 6 months into the conversion course!) then returned to the simulator for a couple of days further training, which included light weight take-offs. 

In a way this seems slightly strange because base training was always done at light weight. There was one particular training captain on the fleet who liked to play a trick on all the new pilots. He would contact the control tower when the pilot under training couldn't hear, or was too busy to notice, and ask them to give a clearance for 3000ft after departure over the radio, but clear the airspace to 5000ft. The pilot under training would hear that they were cleared to 3000ft and knew (or think at least) he (or she in one case) would have to level at that altitude. They would call 3-2-1-now and shoot off down the runway (take-off weight of around 120,000kg or less!) V1, rotate, V2, positive climb, gear up would all happen at around the speed you are reading this! They would pitch up to around 18 degrees when at 500ft the reheats were cancelled. It would all happen so quick that just as they thought they had nailed 250kts after pitching up more and more to contain the speed they would realise they were above 3000ft, pull the throttles back and pitch down, with everyone on the flight deck floating in negative g for a second or two! Most pilots nearly reached 5000ft and were slightly worried about the fact, but of course, the training captain just laughed! 

She was a military jet with 100 passengers connected on behind the flight deck. Although no military jet could cruise at Mach 2 for over 3 hours!!

It does take practice Ray, but once you are used to it, light weights become just as normal as heavy take-offs.

Frazz

  • Like 1
Link to comment
Ray Proudfoot

Frazz,

Fantastic story, thanks for sharing. I have a big grin on my face after reading that. :D Has anyone managed to photograph Concorde perpendicular because it must be damned close to it to keep at 250kts!

It's reassuring the simulated Concorde appears to match the performance of the real one at these light weights. I have yet to keep her at 250kts probably because the reheats are still engaged and throttles are all the way forward. But setting a Noise Reduction distance to less than 4 miles is definitely going to make it achievable.

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Fraser Gale

I once saw a photo of a French Concorde at an airshow I think it was, and they took off with the visor up, at full power, and a photo was taken in the initial climb and it was near vertical! I will see if I can find it.

Frazz

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