odd pitch on landing

[martin-w 3,235]

Well, I've just checked the PC-12 on approach.

 

And the pitch is actually correct, 2 to 3 degrees down, quite normal for the PC-12.

 

Correct at flap 40 and correct at flap 30.

 

Flap 15 on the other hand was another question, airspeed required to match the AoA indicator and correct pitch seemed too high. But don't quote me on that.

 

I think the reason some people may be assuming the pitch is too low, is because it's the actual point of the flight director triangle that indicates zero pitch. Therefore it can give the impression of more nose down than it is.

 

I think if some of you have modified the cfg and ended up with close to zero pitch, then you have ended up with a pitch on approach that isn't as per the real aircraft.

[metzgergva 28]

Well, I've just checked the PC-12 on approach.

 

And the pitch is actually correct, 2 to 3 degrees down, quite normal for the PC-12.

 

Correct at flap 40 and correct at flap 30.

 

Flap 15 on the other hand was another question, airspeed required to match the AoA indicator and correct pitch seemed too high. But don't quote me on that.

 

I think the reason some people may be assuming the pitch is too low, is because it's the actual point of the flight director triangle that indicates zero pitch. Therefore it can give the impression of more nose down than it is.

 

I think if some of you have modified the cfg and ended up with close to zero pitch, then you have ended up with a pitch on approach that isn't as per the real aircraft.

Sorry Martin, but I think it is relevant to speed and aircraft weight. The default settings are definately way off. Just check the the stall speed at MTOW. While clean it it stalls correct at the end of the white arc, it does not stall at all at the end of the green arc with the flaps down as it should. That is a clear indication of too much lift gain from the flaps.

Yes, the PC-12 does arrive at the runway pitch down with Vs x 1.3 but then you pull power and reduce speed so that at Vs x 1.15 you set her down with the nose wheel up.

A simple cure is just as people said above!

[martin-w 3,235]

This thread is primarily about, and I quote "odd pitch on landing". Excessive pitch down. And comments like "flattens it out nicely". My point is that it shouldn't be flat, and unlike those in this thread, I see no unrealistic pitch down.

 

 

I'll try stall speeds later and get back to you.

 

If it's pitched down by minus 2.5 degrees, at the correct Vref for that weight and flap setting, on a three degree glideslope then deck angle is correct, if it isn't, it's not correct. If the settings in this thread, change that, then it's wrong. [i haven't tried them yet]

 

And why is drag_scalar adjustment required?

 

You say at maximum take-off weight, are you aware that max take-off weight is 9921lbs, not the 8400lbs the Carenado is loaded at in the sim? That's very significant in terms of your stall speeds.

 

Don't forget, flight dynamics in the sim isn't as simple as "stall speed is wrong so flaps must be generating too much lift" It may well be that the parameters can be set independently.

 

 

These are the correct stall speeds and Vref speeds at the weight the aircraft is in the sim...

 

 

Weight in the sim is 8500lbs.

 

 

Stall speeds.

 

Flap 40 = 59

Flap 30 = 63

Flap 15 = 66

 

Approach speeds should be + 30%

 

Flap 40 = 77

Flap 30 = 82

Flap 15 = 86

 

If you look at the other thread, you will see our suspicions that Vref at flap 15 is way to fast in the Craenado PC-12.

[martin-w 3,235]

While clean it it stalls correct at the end of the white arc, it does not stall at all at the end of the green arc with the flaps down as it should.

 

Hi Alexander.

 

I have just tested stall speeds, and this is without the modifications suggested in this thread.

 

And don't forget, as I said above, the PC12 in the sim is not at max landing weight, it's set to 8500lbs in the sim.

 

The correct stall speeds, as quoted from the Pilatus website, [Revision to POH document] at a weight of 8500lbs are...

 

 

Stall speeds.         Result.

 

Flap 40 = 59    =    Correct!

 

At Flap 40 you have to climb to get it to stall, otherwise the nose pitches down and there isn't enough trim range to compensate, probably realistic. But yes, smack on the correct IAS.

 

 

Flap 30 = 63    =   Correct! Smack on the correct stall speed.

 

Flap 15 = 66     =  Correct! Smack on the correct stall speed.

 

 

As you can see above, all stall speeds are exactly correct, without the need for any modifications. Carenado got this right, just as they got pitch on approach correct.

 

 

Next I'll test the changes suggested in this thread.

 

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Edit: Okay, I've just tested the changes recommended in this thread.

 

Modifying the cfg in this way has the following effect...

 

At flap 40, at 8500lbs, at the correct Vref specified by Pilatus, on a three degree glideslope it results in... zero degrees pitch up This is wrong! Pitch should be 2.5 degrees down.

 

In addition, the settings throw out the AoA indicator. If you follow the AoA indicator, and fly faster than the correct Vref, it centres, and pitch is closer to being correct, but Vref is then wrong. Engine rpm is also higher.

 

Without the settings mentioned in this thread...

 

Stall speeds are correct for all flap settings.

AoA indicator is correct.

Pitch on approach is correct.

 

The only issue is the one mentioned in the other thread, namely Vref is too fast at  Flaps15.

 

So, no I wouldn't recommend these settings at all.

 

 

 

 

 

 

 

 

 

 

[andresico 0]

I will recommend the settings.

Realism is a kind of "unreal" word when you compare sitting behind a PC-screen and sitting in a real world cockpit.

With standard settings, I could only see both my gauges and the runway on approach using 60% zoom and thats not realistic. We can pan the VC view with our mouse, but will never be as fast (or realistic) as using your eyes in the real world.

 

Its the same with these annoying HSI that Carenado use in many AC (like the B200 and B1900) they are impossible to read withoud using a pop-up screen or 2x zoom and real world pilots dont have that.

 

So thanks for these flap settings. It has made me use this very nice AC again. I had stopped using it and thought it was just another payware (carenado) thing.