I notice that the V-speeds of the longitude are surprisingly high compared to the other jets in msfs. I searched for more information about its vspeeds, but came up empty. Can someone more knowledgeable shed some light on the appropriate vspeeds are, in particular vr, v2, vapp and vref?

45 minutes ago, Andreas Stangenes said:

I notice that the V-speeds of the longitude are surprisingly high compared to the other jets in msfs. I searched for more information about its vspeeds, but came up empty. Can someone more knowledgeable shed some light on the appropriate vspeeds are, in particular vr, v2, vapp and vref?

I think it is fair to say that the Longitude's flight model is a little....wrong.

So, for in sim, here's what works:

For takeoff:

if light, V1/Vr at about 125, V2 at 140

if heavy, V1/Vr at about 135, v2 a 150

At 1,000' reduce power to ITT redline and maintain under ITT redline for duration of climb (since the FADEC doesn't work)

By the way, this is what is making the plane unreasonably powerful (plus some bad flight modeling)

You should technically derate your takeoff also, only going a little into the red on the ITT and meticulously reducing power at 1000'.

The N1/N2/ITT values appear way off, but the ITT is actually the best way to set power in the MSFS longitude.

 

For approach

if light, vref 135, vls 115; liberally add to vref in gusting or turbulent conditions, like I'd add 15 knots in weather to that vref until short final

If heavy, vref 145, vls 125, and again, don't hesitate to add 10 or 15 knots in weather.

Pretend it is a 737-900, keep a nice low deck angle and fly fast.

 

Keep an eye on the AOA and keep a little cushion below the red bar. It reacts poorly to being loaded at approach speed when not under a lot of power.

 

 

 

 

Edited August 29, 20205 yr by cwburnett

Thanks alot. Yeah, I already felt the analog to the 738/9. Flies like a much heavier aircraft on to and landings. 

Just now, Andreas Stangenes said:

Thanks alot. Yeah, I already felt the analog to the 738/9. Flies like a much heavier aircraft on to and landings. 

Oh, also, flaps 2 takeoff, retract to flaps 1 at 165, flaps 0 at 180. That's my suggested SOP for this bird, anyhow...

I really hope Asobo gets to fix the flight dynamics and performance of the Longitude, because it's a fun jet to fly with the fancy avionics. I did a short trip from Munich to Hamburg on it yesterday, and had a lot of fun with it, apart from the fact that I burned half my fuel on this short hop. 😄

6 hours ago, Der Zeitgeist said:

I did a short trip from Munich to Hamburg on it yesterday, and had a lot of fun with it, apart from the fact that I burned half my fuel on this short hop. 😄

Agreed, I did a short flight between LOWI-EDLP yesterday with 50% fuel and ran out on my approach, oops!  Fuel burn seems a *bit* high.

3 hours ago, regis9 said:

Agreed, I did a short flight between LOWI-EDLP yesterday with 50% fuel and ran out on my approach, oops!  Fuel burn seems a *bit* high.

Cruise is all messed up. Plane should burn about 850 per side at cruise at FL430 at about M0.82. It burns almost double that and barber poles at 420TAS instead of more like 470TAS.

 

 

That would explain a lot!

19 minutes ago, regis9 said:

That would explain a lot!

Also, pro tip (LOL), if you want to cruise further, cruise lower. You can increase your range by 50% by flying at 25,000'.

Why? Because the turbine model has been so messed up by the new fuel_flow_max and fuel_flow_min parameters, that while net thrust continues to scale with altitude, fuel flow doesn't. Result being, I can cruise at 450 tas at 25k burning only 1100pph per side, instead of 50% higher than that, at a slower TAS at 45000'.

Didn't test the Longitude.

But the CJ4 in the MSFS tests I did: Cruising at FL310 at ~450 KTAS with 50% fuel, it could not even reach 400 nm. Don't remember how much fuel it was burning, but at that FL the real deal CJ4 should burn ~1820 pph (~0.248 nm/lb) and at FL450 at 430 KTAS it should be burning  ~978 pph (0.44 nm/lb)
 

Edited August 29, 20205 yr by RamonB

On 8/29/2020 at 2:27 AM, Andreas Stangenes said:

I notice that the V-speeds of the longitude are surprisingly high compared to the other jets in msfs. I searched for more information about its vspeeds, but came up empty. Can someone more knowledgeable shed some light on the appropriate vspeeds are, in particular vr, v2, vapp and vref?

This thread makes it all make since now. 🧐 As we have a fuel problem most of us are landing the aircraft heavy (too much fuel in the tanks) which requires a higher approach speed. We have to fly with less fuel even though we have the fuel set to unlimited until this bird is fixed.

When I did a quick look, I think it may actually be that the fuel capacity in sim is much lower that IRL, because the fuel burn seemed close to what I found in a quick search. Also the it seems to indicate PPM but its actually showing PPH based on the quick math I was doing in cruise.

Edited September 16, 20205 yr by willzah

11 hours ago, willzah said:

When I did a quick look, I think it may actually be that the fuel capacity in sim is much lower that IRL, because the fuel burn seemed close to what I found in a quick search. Also the it seems to indicate PPM but its actually showing PPH based on the quick math I was doing in cruise.

That fuel issue has taken on a new life as you can’t get a realistic landing when the bird is too heavy.  Flying unrealistically light is as issue as well.  It’s funny this wasn’t as much of an issue in other sims but FS2020 brings to light why dumping fuel in an emergency is critical for larger aircraft.  I never had to pay attention to this in detail before.  Fuel planning for jets is more critical now because you want to be at a certain weight on short final so your not landing this thing like a 737-900.  I’m really liking this FDE engine in FS2020...

On 8/29/2020 at 12:12 AM, cwburnett said:

I think it is fair to say that the Longitude's flight model is a little....wrong.

 

I just tried an approach to Baudette Int'l (KBDE) in the Longitude, this is only my second flight in this aircraft. I was on the glide slope, gear down, full flaps, slowing from 150 to 120 in preparation for touchdown, and got a Stall warning at 125. The plane was carrying 600 pounds of crew and pax, and about 1,200 pounds of fuel. I executed a missed approach, but was surprised by the stall. The Citation CJ4, with a similar load, stalls at about 90. Either the Longitude's flight model isn't correct, or it is correct, and I incorrectly assumed that it's flight envelope wouldn't be all that much different from the CJ4. I like the Longitude's cockpit: it has autothrottle, which the CJ4 doesn't, and the Garmin G5000 avionics are really nice. I try a few more approaches tomorrow and see where the stall speeds are at different load and flap settings.

Are you using the mod?