Originally Posted by
Flaps1Pls
I have done this exercise in the sim and never came close to a “ face plant “
Does your sim model give an off-axis entry into the microburst model? Fujita's model had been in use for over 20 years when I saw this in a sim, and it was in only one of the sims following an upgrade of the aeromodel.
a microburst is not a circular column of descending air that gets to ground level and then.... does.... a splat like an egg. It may have nearly vertical flow neatly for some point up fairly high, but then it will have a stagnation point in the center of the surface, and a roughly toroidal donut shape from the flow around the stagnations point, and above the donut, you will get an inverted trumpet form of the flow field, you can probably neglect the Coriolis induced axial rotation of the flow field, but that will be there as well in the real world. So. if yon sim sluf is aligned with the center axis, then you get a pitch up due to the flow direction to the aircraft. your stab is trimmed to maintain an AOA on the wing, and that results in a pitch up. m'kay?
Now, look at a planform flight path past yon pesky roundy planform downwash, and that is aligned with the centerline of the aircraft only when your pointy bits are pointing at its center. Every other path will result in yaw towards the core in the entry into the core. Get a bunch of bananas, tape them up by one end with the curvy (Queenslander workshop inspired) bend going outbound, and put the taped ends at the top. pass your wine glass past the bananas, and you will see that the vector is not aligned with the direction of your red wine. That's the yaw bit. If you happen to stall with a yaw rage, fun stuff happens.
FYI, when this was seen in the sluf sim, it was not on the B777 B747 744, A330 MD11 B767 or B757 sim models, they didn't introduce yaw at that time, or if they did, it was not observable in the QTG. Only one of our 3 737 sims had this software at that time, the others didn't behave like this... Progress,
Originally Posted by
Flaps1Pls
3.5 to 4 Gs?
?
A comment was made about the SJ182 plane spinning by another poster. I suspect it is improbable. The stall speed for the B737-500 clean is around 120KCAS roughly. I have the actual data, but that is for 51T and 38T at FL170 for forward and aft limit CG, so I am guessing, in the absence of the AFM which has the SL VS for various configs as well as it does have the buffet boundary for high and low-speed buffet. For a stall speed about 120, a CAS of double that would give a 4g pull to buffet,
Originally Posted by
Flaps1Pls
That's what the pitch limit bars are for.
Indeed.
The PLI is a thing of beauty. they also are dynamic and as you race up to them. they will be racing down to meet your pitch up input, the pilot response, and the aircrafts alpha stable pitch response, just add a bit of G, a bit of turbulence, and a new model that gives not just pitch, but pitch, yaw, and roll as well.
Yup, thats what the PLIs are there for.
Originally Posted by
Flaps1Pls
180 deg/sec roll rate ?
The roll rate on UAL585 and USAir 427 exceeded 180/s, for starters.
Really roughly,....
A 2 aileron Pitts S1 got about 150/s, 4 ailerons about 230/s on a good day An A-4, 720/s, helmet knockin'. Rudder on a B737 gives about 25/s secondary roll, aileron gives about 45/sec. very roughly... A T-38/F-5 has 2 rates, the wild rate or the insane rate. P51 around 100/s these are rough rates, WW2 figher roll rates were as good as they could get, but they are anaemic, give beautiful graceful aeros though, and a big difference if going with or against the prop. The F-4 had fair rates, even better if you put in aileron at alpha over 12....
Transport aircraft have relatively low rates as that is what is needed. tactical aircraft have greater rates, exact figures will depend on what the book said, and what the control input is. Oddly, a number of transport aircraft have a real problem getting full deflection on the ailerons anyway, as the control yoke gearing to the deflection needs hands to be swapped to get the rotation angle on. That came up in one report a long time back. ( I think that was actually the B734 of USAir IIRC...) On other planes, the addition of a hard rudder is an issue, unless you have a parachute, The A300 was the poster child for that, and the same structure more or less went on to the 310, 320, 330 340.. at least. alternating torsion-bending suuuuuucks with harmonic yaw rates. AA587.
Originally Posted by
Flaps1Pls
WTF?
Well may you say WTF, as nothing will save the Governor Gen'l....
Originally Posted by
Flaps1Pls
I
You have got to try really hard to screw up this badly in a B737.
And yet collectively, we do so. If at first...
Originally Posted by
Flaps1Pls
I
It wont be the aircraft.
Airplanes are humble tools. They are the result of our design, so it's always us...
Fun fact, as far as sims go, they can be great to questionable. One sim you could take to an aerodynamic break, and the plane would climb at 6000FPM below that speed. I want that on my own jets. It was also nearly impossible to envoke a wing drop, but the flight testing had great movies of the belly uppermost in a stall. Outside of 1.3Vs and MMO, a lot of what you see is questionable. Even the departure stuff was an issue. At one conference on sims, the point was made that the airlines were routinely training in a sim that the model had not qualified data for. The OEMs in the part 125 testing obtained data that was not needed beyond (trying to recall.... ) 8 Seconds? from meeting the min speed condition. I suggested that there was a bucket of data in accident archives that provided all of the info that was needed, and got a lot of frozen stares in response. 2 major OEMs were bemoaning the data desert, and also stared blankly when I suggested using accident data.