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scottb613

Lear 35A - Real World Fuel Planning Profile

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Hi Folks,

 

Just a bit more real world information - the fuel planning profile off of Fltplan.com for a Lear 35A - granted - I'm sure the model won't match perfectly but at least it's some actual data for ballpark comparisons... The profile stated M .75 but I calculated M .77 - it's probably an error on my part... Includes both the detailed and hourly fuel burn method... The data is available to anyone on their site - photobucket stepped down the resolution as my original was clear - I can send it to anyone that needs it as well...

 

 

2016-11-29%2012_35_40-AC%20Select%20to%2

 

 

Regards,
Scott

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That's pretty cool.  Is there a way to change the profile mach cruise speed?  I don't pay for gas (or overhauls LOL) so I pretty much go as fast as possible.  I'd like to find some fuel planning for Mach .80-.83

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Nice one, just something that gets me wondering, the profile reads a maximum V/S in the lower altitudes of about 4000fpm. The Flysimwear Lear gets me easily twice that at close to MTOM using MCP, is there any reason for that?

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Hi Ryan,

 

They have other profiles but they are at fixed speeds - let me see what else they have...

 

Hi Emi,

 

I may have misunderstood your post - so you are saying you see 8000 FPM ? I think this might pertain to a question asked in another thread - I don't think we just firewall the throttles on this bird - you have to set a reduced takeoff thrust to emulate real life... Even when I firewall the throttle - as soon as the gear and flaps are up - I'm backing off the throttle as I'm already around 1500 feet and putting in substantial nose down trim... I use 90% N1 in the climb and use the Speed Hold at 250 Knots... I think I see greater than 2000 FPM but less than 4000 FPM for most of the climb...

 

Regards,

Scott

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Nice one, just something that gets me wondering, the profile reads a maximum V/S in the lower altitudes of about 4000fpm. The Flysimwear Lear gets me easily twice that at close to MTOM using MCP, is there any reason for that?

 

There are readily available actual performance charts to compare with but the above quoted chart is a good working guide for climb and cruise performance.The high altitude levels seem to indicate an economy cruise based on the TAS number but overall that is a good profile.The published performance charts will allow you to draw your own conclusion.

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Hi Gary,

 

Thanks for the reply - I recall seeing a post where you mentioned having had some serious time flying these birds...

 

Could you just provide a little more guidance on takeoff thrust and getting setup in your initial climb - what you typically did - and - what would be a good rule of thumb for us to use (providing we don't want to go the charts on each and every takeoff)... Did you guys really go to the charts on each and every takeoff - or - only on those that might have questionable performance hazards ?

 

Is the published Vref too low for the model ? I seem to have to be at around 130 KIAS - on final to maintain the proper sight picture and glide slope...

 

And finally - there doesn't seem to be any "Cruise Table" in the AFM - or am I just missing it ???

 

Thanks !

 

Regards,

Scott

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Hi Emi,

 

I may have misunderstood your post - so you are saying you see 8000 FPM ? I think this might pertain to a question asked in another thread - I don't think we just firewall the throttles on this bird - you have to set a reduced takeoff thrust to emulate real life... Even when I firewall the throttle - as soon as the gear and flaps are up - I'm backing off the throttle as I'm already around 1500 feet and putting in substantial nose down trim... I use 90% N1 in the climb and use the Speed Hold at 250 Knots... I think I see greater than 2000 FPM but less than 4000 FPM for most of the climb...

 

Regards,

Scott

 

Hi Scott,

 

I'm using the MCT values from the Climb performance chart on page 5-35 in the manual.

I can not find any reduced power values for the climb, only for takeoff which I'm using already.

 

Do you by any chance have to reference values how it's done in real life?

Where did you take the 90% from?

 

Greetings,

Emanuel

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Hi Emanuel,
 
OK - sounds like you're a step ahead of me - the 90% was just to keep my climbs manageable and I figured in most cases it was less than MCT...
 
I'm still working on this chart:

f7853d1d627bb8bfd36a713907d0ff9a_zpsdolx


I'm not sure I'm reading it correctly - for example -

  • 0 degrees @ Sea Level limits to 90% N1
  • 100 degrees @ Sea Level limits to 92% N1 (the altitude is irrelevant)

???

 

The MCT chart for climb has me wondering how they do it in real life - do they really check and document MCT for each altitude along their climb based on RAM air temp - or simply swag it...

 

 

Regards,
Scott

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Hi Gary,

 

Thanks for the reply - I recall seeing a post where you mentioned having had some serious time flying these birds...

 

Could you just provide a little more guidance on takeoff thrust and getting setup in your initial climb - what you typically did - and - what would be a good rule of thumb for us to use (providing we don't want to go the charts on each and every takeoff)... Did you guys really go to the charts on each and every takeoff - or - only on those that might have questionable performance hazards ?

 

Is the published Vref too low for the model ? I seem to have to be at around 130 KIAS - on final to maintain the proper sight picture and glide slope...

 

And finally - there doesn't seem to be any "Cruise Table" in the AFM - or am I just missing it ???

 

Thanks !

 

Regards,

Scott

 

Scott,

 

Every takeoff requires referencing the takeoff power chart for the ambient conditions, the N1 setting is what gives the required thrust for all the initial take off and climb performance assuming an engine failure.It is required to meet the performance chart data for climb gradients, takeoff distance etc. It is always worst case scenario, you assume you are going to have an engine failure whenever you takeoff.

 

After takeoff you reference a "maximum continuous thrust N1" chart for a given altitude in the climb so you are not exceeding the limit, in reality I rarely referenced it, we observed the manufacturer recommended 795 ITT limit for prolonged engine life (hot section) as often as possible.Some times with anti ice on in the climb you may need to check the N1 as the ITT would be higher but generally staying around 795 in the climb would keep you under any N1 limit requirement. 

 

Vref varies from a low of 115 to 129 dependent upon your landing weight (flaps 40).Fly Vref +10 or what ever the conditions dictate in gusts and target Vref at threshold.Again all the chart data requires flying the numbers to get the result. 

 

There are climb and cruise charts in the AFM for all weights located in a supplement which you may not have and they are in tabular format not graphs like the takeoff and landing data is.Be aware you are not going to see actual performance numbers, fuel burn etc. from the AFM work in the sim, it does not have that level of realism.It is still entertaining to use but if you want the real deal it is about $1500 an hour for a Level D simulator at FSI which is about as real as you can get.

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.Be aware you are not going to see actual performance numbers, fuel burn etc. from the AFM work in the sim, it does not have that level of realism.

 

Hi Gary, that was the next question on my mind. I was going to do some test flights this weekend to try to establish some numbers for a PFPX profile? Hopefully the fuel burn won't be too far out.

 

In climb and descent, I am finding this sim prefers IAS hold over VS hold. The latter requires Auto Pilot (ENG) to be de selected to properly establish the VS, (There being some oscillation before VS settles) then re ENG and select Alt Sel, VS, in order to hold the VS. Did you find the same behaviour in the aircraft?

 

Finally, during the after take off/climb flow, ( and descent/approach) did the PF select any Auto Pilot functions?, or was that the PNF action. I ask due to the need in this sim to "fly" the aircraft properly on "Bird, Ball and Needles" whist setting the AP functions as well...:-) Without a guy on the right, the workload is rather high!

 

Cheers

 

David

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Hi Gary,

 

Thanks for all the additional information - taking it all onboard... Yeah - understand - I'll take the numbers with a grain of salt and focus more on procedures with this plane...

 

Regards,

Scott

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Hi Gary, that was the next question on my mind. I was going to do some test flights this weekend to try to establish some numbers for a PFPX profile? Hopefully the fuel burn won't be too far out.

 

In climb and descent, I am finding this sim prefers IAS hold over VS hold. The latter requires Auto Pilot (ENG) to be de selected to properly establish the VS, (There being some oscillation before VS settles) then re ENG and select Alt Sel, VS, in order to hold the VS. Did you find the same behaviour in the aircraft?

 

Finally, during the after take off/climb flow, ( and descent/approach) did the PF select any Auto Pilot functions?, or was that the PNF action. I ask due to the need in this sim to "fly" the aircraft properly on "Bird, Ball and Needles" whist setting the AP functions as well...:-) Without a guy on the right, the workload is rather high!

 

Cheers

 

David

 

David,

 

Can't help you with PFPX not familiar with the add ons, I just sim as it is. For the sim if you are doing a long flight just note the hourly fuel burn and use that for future reference.Even in the real world you could spend hours going over cruise performance charts but in reality you will never get direct climbs and descents that the charts are based on.We used average hourly fuel burn for planning. In dial up internet days we initially used professional flight plan services for long distance flights, after a few years we found our average burn numbers were consistently within 200 lbs of what the computers could do so we reverted to inputting them into DUATS planning and never looked back.

 

Real world you don't need to disengage the auto pilot to initiate a pitch change to establish a climb or descent.The outboard end of each control wheel has a barrel style switch which is used for trim control (elevator and aileron) in conjunction with an arming button.When the autopilot is engaged moving the barrel knob alone you have auto pilot pitch and roll function which will override any active AFCS mode like ALT or HDG etc. For a climb or descent just adjust the pitch attitude using the knob to establish the desired airspeed or vertical speed then reselect SPD or VS on the AFCS panel.The knob and that function are not incorporated in to the sim version of the Lear 35, so you have to deselect the active mode and use your controller trim to simulate that action. I always used VS for descent and SPD for climb.

 

As to who does what it would be a matter of personal preference, I would usually do AFCS actions myself unless I needed two hands on the control wheel for a large trim motion and there was excess control pressure required. I preferred to actuate spoilers in flight while adjusting pitch trim as it requires about three seconds of trim motion due to a rather abrupt pitch change that occurs if the trim motion is not timed correctly with switch actuation.In our operation the PF always deployed the spoilers in flight and on landing, the PNF would do the retraction during after landing checklist.The PNF is there as you need and follows your actions or requests.In the sim you need a third hand sometimes because you can't readily access a button or switch, in the aircraft it can be accomplished as simply as moving your thumb on the control wheel to engage nose wheel steering.

 

Workload can be high at times even in a crew situation but that is where the coordination comes in with established procedures.In small flight operations everyone knows each other and when you have flown with the same people for many years it all becomes very natural.A nod or hand gesture to indicate an action desired when there is a lot of multi tasking going on may be all that is required.In airline op's you may not see the other guy for years hence the need for very regimented procedures as to who does what.

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Thanks for the heads up Gary, appreciate it!

 

.The outboard end of each control wheel has a barrel style switch which is used for trim control (elevator and aileron) in conjunction with an arming button.When the autopilot is engaged moving the barrel knob alone you have auto pilot pitch and roll function which will override any active AFCS mode like ALT or HDG etc. For a climb or descent just adjust the pitch attitude using the knob to establish the desired airspeed or vertical speed then reselect SPD or VS on the AFCS panel.The knob and that function are not incorporated in to the sim version of the Lear 35, so you have to deselect the active mode and use your controller trim to simulate that action. I always used VS for descent and SPD for climb.

 

Yes that's what I find, although I have elevator and aileron trim assigned to a 4 way "hat", there is no arming switch in the simulation therefore, as you say, the AP needs disengaging and re engaging to set the new trim. I find SPD hold works well in this sim, especially in climb and is easier to use in descent. The AP can stay in and its just a matter of easing the thrust levers back to the desired airspeed. It makes for interesting arithmetic when given a crossing restriction!:-)

 

The work flow between PF/PNF is of interest, due to my use of a program called Multi Crew Experience. That allows us to make our own flows, or use accurate flows from flight manuals. The flows being accomplished by the PNF, thus leaving you to fly the aircraft. Same with checklists, that are interactive by the means of the virtual "First Officer" being aware of the position of every switch.

 

If we get the flows correct, for each supported aircraft, then we are a step closer to that aim of the simulation, i.e. "Suspension of disbelief"!

 

Being an earlier generation jet, this simulation is certainly more fun to fly than say the 'Bus! No dial a speed and let the computer fly the computer!:-)

 

Best Regards,

 

David.

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I'm not sure I'm reading it correctly - for example -

  • 0 degrees @ Sea Level limits to 90% N1
  • 100 degrees @ Sea Level limits to 92% N1 (the altitude is irrelevant)

???

 

Rather some 93% for 100%, but yes, that's how to read them.

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