Xtreme prototypes GLJ25

[Ray Proudfoot 8,903]

I can't get my head around the take-off. We have to set Trim to around +1.9 for take-off but as soon as the aircraft is airborne the nose comes up and it wants to climb at a ridiculous rate. I'm forced to push the yoke forward quite forcibly to keep the climb rate to sensible levels and to trim down aggressively.

When I have it under control and engage the a/p the trim is a negative number. I always thought the point of setting take-off trim is the aircraft would be trimmed for a reasonable climb rate.

I'm going to try experimenting with lower trim values and see how things pan out.

On a different point on the EICAS display there are two notifications about standby pumps being off. If I turn them on the display doesn't change. Anyone else seeing this and know how to clear the display.

[MartinRex007 390]

Hi Ray,

I usually leave all the trim set at 0, then I select HDG and ALT and VS on the ground. Power to 70% RPM brakes set, then power to 90% on the roll  and rotate at about 115-120 knts with 10% flaps, climb out at 3500ft/min which is about 8-10% pitch, at 240knts, watching the speed and pulling the power back to about 82%,  trim down to about -3% so the nose stays at that 10% and once on the stable climb hit AP and off we go. See if those setting help?

Cheers

Martin

[Ray Proudfoot 8,903]

Thanks Martin. I’ll give those values a try tomorrow. The pitch trim setting sounds far more realistic.

[Ray Proudfoot 8,903]

@MartinRex007, I tried 0 for the pitch trim but had to pull back far too much before the nose-wheel left the ground. Not good. Next flight I tried +0.4 and that was better. I suspect around 0.5 - 0.8 is probably ideal.

I'm getting used to her handling now and flights are much better. It took me months to get accustomed to Concorde but after just a week with this I'm pretty happy.

[crippy1 1]

Hey, I've looked through the manual but I am having trouble getting the aircraft to track VOR's. I can be bang on the GPS / P3D drawn line from a VOR but the HSI will still not line up properly. In one instance the needle was full deflected left when the actual course was to the right....Am I doing something wrong? What have I overlooked?

[Nyxx 6,993]

To set TO trim you use the light right in front of you, trim back to light comes on, trim down a bit to light goes off trim up a little bit light on.

Perfect trim

[Ray Proudfoot 8,903]

29 minutes ago, Nyxx said:

To set TO trim you use the light right in front of you, trim back to light comes on, trim down a bit to light goes off trim up a little bit light on.

Perfect trim

What’s the trim value when you’ve done that David?

[Nyxx 6,993]

no idea also it would depend on fuel ZFW.

But that's what I use to set Trim . Just don't trim back to light comes on and leave it, you have to find the sweet spot.

Edited March 10, 2018 by Nyxx

[MartinRex007 390]

If you mouse over any one of the 3 trim tab indicators behind the yoke it should show the number setting for trim, might have to have labels on?

Martin

[Ray Proudfoot 8,903]

Does the trim value vary by TOW? I haven't checked the full manual. You'd expect to see a table if it does.

[Xtreme67 16]

On 3/6/2018 at 9:47 AM, Ray Proudfoot said:

I've had a reply back and then said the yaw damper thing is something they will look at in an autumn update.

What you are describing is normal in the current software version. This is because the Learjet 25 has a "dual" yaw damper system which is not supported in the simulator.

In the sim, controls are provided for one, primary yaw damper system only (activated by the CTRL+D shortcut). So we had to create our own code to simulate the dual yaw damper system of the Learjet. This has the disadvantage of bypassing the CTRL+D command; a compromise made for realism over user-friendliness.

I believe you have a good point and I've added your comment to our wish list for the next version (v3.0) scheduled to be released in the fall. I've asked the team to check if there is a way to keep the CTRL+D command while preserving the dual yaw damper system of the Learjet. I believe this will be possible.

[Ray Proudfoot 8,903]

Thank you Alain. Fully understand the desire for accuracy in the Lear 25 model. But having to switch views (however briefly) when hand-flying the approach to turn off Yaw Damper is inconvenient so your offer to look at changing it is appreciated.

[Ray Proudfoot 8,903]

I'm slowly mastering this nice aircraft. One question on the correct landing procedure. Should I kill throttles at 20ft or thereabouts and then land with minimal flare?

How I do then slow the aircraft? I'm landing with flaps 20 around 128kts. I engage reverse thrust (no braking) and then kill reverse around 70kts when I engage manual braking.

Is that correct? No spoilers on landing as they would normally be engaged on larger aircraft automatically. I'm guessing they're only used when airborne to slow the aircraft.

One other point. Given the engines are so powerful I'm surprised I need to advance the throttles almost half-way before the aircraft starts to move. Is that how the real one was? Seems odd. Maybe some glue on the tyres that needs cleaning off?

[Rossco 23]

Hi Ray,

After some research I use the following technique, most of the procedure gleaned from the CAE Simuflite LR25 Cockpit Reference Handbook I found on the web.

Apparently the real aircraft, having the engines at the rear plus a "T" tail actually pitches up when closing the throttles so in real life when flaring & closing throttles the PF has to counter this which I don't find happens in the sim.

I usually disengage the Yaw damper during flare (as per CAE) & once touch down is achieved I deploy the spoilers followed by the reversers once the front wheel is on the ground. I then leave the reverse thrust engaged until around 60kts (this from CAE Manual) & apply brakes throughout the landing. The manual states "Brakes......As Required."

Re the initial roll, not sure if it's true to life however I find I have to increase throttle to around 70% to get her going then adjust depending on the load.

Hope this is of some help.

Edited July 24, 2018 by Rossco

[FDEdev 955]

10 hours ago, Ray Proudfoot said:

1.Should I kill throttles at 20ft or thereabouts and then land with minimal flare?

2.How I do then slow the aircraft? I'm landing with flaps 20 around 128kts. I engage reverse thrust (no braking) and then kill reverse around 70kts when I engage manual braking.

3.No spoilers on landing as they would normally be engaged on larger aircraft automatically. I'm guessing they're only used when airborne to slow the aircraft.

One other point. Given the engines are so powerful I'm surprised I need to advance the throttles almost half-way before the aircraft starts to move. Is that how the real one was? Seems odd. Maybe some glue on the tyres that needs cleaning off?

1. Depends on your excess energy. If you are rather fast, you can reduce thrust earlier, if you are a tad slow you should leave the thrust on down to 10ft

2. Why flaps 20? I don't think that this is an approved flap setting. Since the Learjet has a wing that is optimized for high speed you should always use flaps 40 since you need all the lift you can get to reduce the approach speed and apart from that, full flaps greatly increase drag which helps slowing down after touch down.

128kts with flaps 20?  What's your weight? It's important that you know your actual weight since the approach speed varies a lot with weight.

On the Learjet 25 the difference can be in excess of 20kts. If the runway is long enough your technique to slow down is acceptable but bear in mind that on almost every airport use of more than idle reverse thrust is forbidden due to noise.

3.Extending the spoilers after touchdown is the first and most important item after touchdown! They increase drag and will put more weight on the wheels. They don't extend automatically because the Lear is a very old design which simply doesn't have automatic spoilers. The old jet airliners didn't have automatic spoilers either.  

4. Due to a bug in the FSX/P3D friction simulation it's up to the FDE designer to correct this problem by modifying the FDE accordingly.  

Check this video and note how much thrust is needed to get the Lear moving with just a single engine running.

If you can taxi with a single engine at idle it's usually an indication that there's quite a bit of thrust available at idle…..https://youtu.be/K88r1CMOh0o?t=442

 

Edited July 25, 2018 by J35OE