Cessna Citation Longitude Performance issues

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43

I’m not giving up! I will keep trying to get an answer to this question from the sim developers. It might take persistence, but with enough effort, I think they will see that a large number of people want a change.

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44

Another update. Another lack of a fuel capacity fix. :roll_eyes:

2 Likes
45

Maybe devs lost the encryption key to the plane and can’t make any changes to it anymore. Now we are waiting on a quantum computer to decrypt the plane so the changes can be made. just jk.

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46

Try my modification project for the Longitude over at flightsim.to.

1 Like
47

The plane is literally unflyable and unenjoyable. It’s such a joke that the APU doesn’t even drain fuel, which tells me it’s simply a flip of a switch that turns on a sound. Plus said sound is so horrible you can hear the wave file repeat from the start over and over again.

I’ve been INOP from the sim for over two months now because of their lack of effort to fix and finish stuff we paid top price for. The chalkboard of issues was building and building for 3 months straight and they just sat there looking at it until two weeks ago where they FINALLY changed some statuses to “Started”. But hey, at least we got them to change the loading screen.

2 Likes
48

Honey, I think we SHRUNK the pilots!

They keep getting things wrong or make things worse than they were. The pilots were already undersize, now they’re too short. Their heads are below the height of the glareshield!!! That’s ridiculous. You’d never see anything other the sky while looking forward if you were that height. The headrest of the seats are not supposed to be at the same height as the top of the head. It should be much lower, just above the neck.

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Compare with a screenie taken with an earlier patch. Even right here the man is sitting slightly lower, and the woman is much lower, an impossible position IRL, but this time around, they actually hid the co-pilot under the window.

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49

One reason this may be happening is if you don’t have pitot heat on.

50

Thank you for this great improvement

51

Great mod, and thank you.

I’ve had a couple of random CTD though when trying the mod. Can’t pin it down to anything specific. The first I was editing the flight plan mid flight in the FMC (and maybe thinking this is unrelated to your mod, but not sure - I also use the WorkingTitle G3000 mod which, as far as I can tell, seems to work with your mod without conflict?). The second I was mid flight, cruising over the Atlantic testing out a long run from EGPH-KJFK. All going well, at FL44, scooting around the plane with the drone camera - tried to switch back to cockpit and boof - CTD.

Anything you’re aware of that might cause that? Generally my MSFS has been rock solid and pretty much no CTD after they fixed the USB controller issue back in patch 2 I think.

52

I haven’t modified anything that should be the cause of CTD behavior. I’ve experienced a handful of recent random CTDs as well, both with this a/c and others. Sometimes right in the middle of a flight - like you experienced with stock aircraft, and sometimes in specific situations that can be reproduced. I also use the WT G3000 mod - it’s more likely that product would cause CTD behavior because of the complexity of programming - it interfaces with the scenery data to interpret and display information. I’ve had CTDs in specific geographies that are reproduceable - such as over western Washington state for example. I can trigger a CTD using a specific flight profile over that scenery. Don’t know if it’s a scenery render error that’s causing the system to go unstable or a problem with WT G3000 mod causing instability trying to display or interpret data.

53

Thanks for the reply. That makes sense. I will maybe try without the g3000 mod for a while to see if that improves stability. Its hard to know when it happens so rarely.

54

Just to let you know how my long range test went tonight. So generally good, and feels realistic, but you will know better than me.

Started out with full fuel load and default weights. So total take off weight was 39,500Lbs, so max weight.

Route was:
EGPH (R24), departure GOSA1C
GOSAM
RUXIN
H5620
H5628
H5536
H5442
H5348
TUDEP
MIGLI
USBAM
TOPPS
ENE
KJFK (ILS 22R) via STAR ROBER2 22R

The world map shows this as 2,999Nm with a 6hr 24min flight time

Little Nav Map shows this as 2,933Nm

I flew at FL440, no issues in the climb - let the AP and AutoThrottle do their things. At 44,000ft I was cruising at Mach 0.71 - mainly because for most of the flight I was flying straight into a 120Kts headwind. I was getting betwee 850 and 950 PPH fuel flow per engine in the cruise.

I ran out of fuel at ENE just South of Portland - was down to 2% fuel by then. I loaded up another 30% and made it all the way to JFK without issue.

The world map shows that distance as about 2,644Nm.

So is this what you might expect given the headwind?

55

If you had a 120kt headwind the whole way that’s probably about the range one would expect for this a/c. Can you report your unadjusted Mach cruise number and/or your effective ground speed?

I’m working on a revision that will improve time to climb and fuel consumption to values that are even closer to spec. Might give you a couple hundred more nm range in the the same circumstances, but that’s draining the tanks dry as you did - no reserve at all. Normal “still air” range for the type is 3500 nm at M0.80 with fuel reserves. Obviously flying into the jet stream for 7+ hours is going to knock that down quite a bit!

56

Not sure how to get the unadjusted Mach cruise number. In fact the only way I could find to even see the Mach number at all was from the tooltip on the speed adjustment dial - couldn’t see it on the PFD at all. Ground speed in the cruise was around 320Kts from memory and TAS was 420Kts or so. Headwind was slightly off centre. Hope that helps

57

Divide TAS by approx 574 (speed of sound in kts at 44k ft). BTW a TAS of 420 is a little slow for this a/c. And in particular with the oddities of the Asobo turbine model (and the compromises I had to make to get reasonable approximations of IRL performance) you’re actually going to get better range flying at about M0.8 or M0.81 or so. That’s roughly 458 to 465 kts TAS. And weirdly as well you’ll get slightly better range flying a little lower - like FL410 or so, especially when the a/c is heavy. The real ac likes being as high as possible but with the specific fuel consumption lapse rate not correctly following the thrust lapse rate with altitude in Asobos underlying turbine model, my mod will do better a little lower down - if maximum range is your objective.

58

Cool, thanks for the tips. I’m a noobie with the aircraft, and I flew it with the speed control setting set to managed not manual - in managed setting I get no control over the speed as far as I can tell (turning the speed dial has no apparent effect (at least the tool tip doesn’t change), so Mach 0.71 is what the AP set it to. I just went with it. The only way I could go faster would have been to change the speed setting to manual and then adjust the dial then - that is using auto throttle. I’ve no idea if I’m doing the right thing with that - very much experimenting right now.

59

I would suggest setting the authothrottle speed control to manual and using the Mach setting when at cruise altitude. Clearly the managed setting isn’t doing you any favors. M0.8 to M0.82 is probably the best cruise speed for my mod of the a/c. IRL the Longitude is actually a hair more efficient at slightly lower Mach number (.76 to .78 M), especially as it gets lighter burning off fuel and climbing higher. However I still haven’t figured out a way to make that work while still getting realistic fuel consumption and other performance measures to work. Again with the Asobo turbine fuel burn modeling issues.

60

Using the procedure from Dakfly0219, above, you can always monitor the true airspeed as you climb (via the PFD) to avoid any under speed/ over speed issues.

A normal climb on a long cruise for this aircraft would be 290KIAS (above 10,000’), transitioning to 0.78M. The attached tables show the TAS values for different altitudes, which can help manage the climb. Keeping an eye on the VS and lowering it as required should bring you the desired altitude, after which you can turn on the A/T and set the final cruising Mach number.

Just remember that these tables are using ISA values. If the OAT value is higher/ lower, you will need to compensate slightly.

PRESSURE ISA TEMPERATURE MACH NUMBER
ALTITUDE © (F) 0.73 0.74 0.75 0.76 0.77 0.78 0.79 0.80 0.81 0.82 0.83 0.84 0.85 0.86 0.87 0.88 0.89 0.90 0.91 0.92 0.93 0.94 0.95 1.00
25000 -34.5 -30.2 439 445 451 457 463 469 476 482 488 494 500 506 512 518 524 530 536 542 548 554 560 566 572 602
26000 -36.5 -33.7 438 444 450 456 462 468 474 480 486 492 498 503 509 515 521 527 533 539 545 551 557 563 569 599
27000 -38.5 -37.3 436 441 447 453 459 465 471 477 483 489 495 501 507 513 519 525 531 537 543 549 555 561 567 597
28000 -40.5 -40.9 434 440 446 452 458 464 470 476 481 487 493 499 505 511 517 523 529 535 541 547 553 559 565 594
29000 -42.4 -44.4 432 438 444 450 456 462 468 474 479 485 491 497 503 509 515 521 527 533 539 545 550 556 562 592
30000 -44.4 -48.0 430 436 442 448 454 460 466 471 477 483 489 495 501 507 513 519 524 530 536 542 548 554 560 589
31000 -46.4 -51.6 428 434 440 446 452 458 464 469 475 481 487 493 499 505 511 516 522 528 534 540 546 552 557 587
32000 -48.4 -55.1 426 432 438 444 450 456 462 467 473 479 485 491 497 502 508 514 520 526 532 537 543 549 555 584
33000 -50.4 -58.7 425 430 436 442 448 454 459 465 471 477 483 489 494 500 506 512 518 523 529 535 541 547 553 582
34000 -52.4 -62.3 423 428 434 440 446 452 457 463 469 475 481 486 492 498 504 510 515 521 527 533 538 544 550 579
35000 -54.3 -65.8 421 427 432 438 444 450 455 461 467 473 478 484 490 496 501 507 513 519 525 530 536 542 548 576
36000 -56.3 -69.4 419 425 430 436 442 448 453 459 465 471 476 482 488 493 499 505 511 516 522 528 534 539 545 574
37000 -56.5 -69.7 419 424 430 436 442 447 453 459 465 470 476 482 488 493 499 505 511 516 522 528 533 539 545 574
38000 -56.3 -69.7 419 424 430 436 442 447 453 459 465 470 476 482 488 493 499 505 511 516 522 528 533 539 545 574
39000 -56.3 -69.7 419 424 430 436 442 447 453 459 465 470 476 482 488 493 499 505 511 516 522 528 533 539 545 574
40000 -56.3 -69.7 419 424 430 436 442 447 453 459 465 470 476 482 488 493 499 505 511 516 522 528 533 539 545 574
41000 -56.3 -69.7 419 424 430 436 442 447 453 459 465 470 476 482 488 493 499 505 511 516 522 528 533 539 545 574
42000 -56.3 -69.7 419 424 430 436 442 447 453 459 465 470 476 482 488 493 499 505 511 516 522 528 533 539 545 574
43000 -56.3 -69.7 419 424 430 436 442 447 453 459 465 470 476 482 488 493 499 505 511 516 522 528 533 539 545 574
44000 -56.3 -69.7 419 424 430 436 442 447 453 459 465 470 476 482 488 493 499 505 511 516 522 528 533 539 545 574
45000 -56.3 -69.7 419 424 430 436 442 447 453 459 465 470 476 482 488 493 499 505 511 516 522 528 533 539 545 574
1 Like
61

Nice data!

62

Thanks for the help and your great mod. I’m preparing for a planned tour of all the capital cities in the world - all 227 of them, and I;ve been working on finding the most efficient route. The best I have so far includes a 3,725Nm leg from Mexico City (MMMX) to Papeete in French Polynesia (or Tahiti) (NTAA).

I tested that flight tonight in the Longitude using your mod. I stripped back all the weight - just me and the fuel :grin: Not even a co-pilot. I took it up to 41,000ft and set the speed to M0.81 as you suggested. I used a fairly steep descent at the end to maximise the effciency in the cruise, and I made it - landing in Tahiti with about 16 gallons of fuel left…so it was close! At cruise, I was getting about 460TAS and 430GS into a 30-40 Kt wind most of the way. Fuel flow was about 820 PPH per engine - so noticeably less than my previous test.

So all in all it looks like I can get my round trip to work without having to make a mid flight stop for the longest leg. My total trip will be 109,000 miles…

1 Like