Blackbird Sims / Milviz Forum Archive

Dear friends,

1)After using the P3D Instant Replay the airplane crash (not the sim),the airplane (ie. as you hit another plane)

2)Well, I tried a landing pattern with 300kt then I reduce to 250kt,man, there´s something wrong with this FDE (airfile), the airplane is unstable with up&downs, with all due respect, don´t tell me about graphics or that was tested with Wind Tunnel and Flight Test data or that´s the way it is.

I tried to change all settings (sensitivity, null zones) I´m using TM Warthdog Stick&Hotas with P3D (direct input),no FSUIPC calibration.

I was part of Dreamfleet and PanelShop team (late 90s till 2006) and I had long arguments that time with programmers about our DF 737 and later DF 727 (They showing me graphics and I kept telling them: "but the real plane doesn´t react this way"), only after filming from a real flight, the aircraft behavior in a steep turn,landing,pitch/power in several situations they believed me and finally change the FDE,the result was the best addon that time (prior the PMDG time).Unfortunately I cannot use my camera now because I left military 22 years ago and the plane I´m flying now wouldn´t help in this issue (FBW) .

I understand the team´s hard work to give us this complex plane,but believe me,It´s not OK, try a take off, join a traffic pattern maintain 250kt, make at least 2 circuits,or perform a steep turn, (180º for each side) and observe its behavior (pitch&roll).

The good part in my opinion is the aircraft behavior after Take Off,stable, (far better regular F-4E) and pitch during final apps).

Thanks

Hamilton

Hamilton wrote: 1)After using the P3D Instant Replay the airplane crash (not the sim),the airplane (ie. as you hit another plane)

The ADV uses an external FDE. An incorrect solver initialization (using Instant Replay) will cause unexpected aircraft behaviours.This *could* also happen after TacPack aircraft re-init after killed.

Not a bug, a "limitation".

Hamilton wrote: 2)Well, I tried a landing pattern with 300kt then I reduce to 250kt,man, there´s something wrong with this FDE (airfile), the airplane is unstable with up&downs

From TO-1 Page (6-6):
"Landing Configuration
In the landing configuration, pitch or airspeed changes require few, if any, trim changes to relieve stick pressure. This is due to control system friction and weak stick centering. Landing at aft CG positions require more attention to AoA control than landing with forward CG. This is due to increased stick sensitivity and mild nose rise tendency at about 18 units AoA...."

From "Limited Performance and Flying Qualities Evaluation of the F-4E with the retrofit two-position maneuvering slat kit":
"Power Approach Configuration Evaluation
Longitudinal flying qualities were satisfactory but were adversely affected by low static stability in the 17 to 20 units AoA range. This region of reduced stability made precise control of AoA moderately difficult during landing approaches at 19 units AoA..."

The model has been validated by a F-4E pilot and no issues at this respect (Landing Configuration handling) were raised.

Alvaro wrote:
From TO-1 Page (6-6):
"Landing Configuration
In the landing configuration, pitch or airspeed changes require few, if any, trim changes to relieve stick pressure. This is due to control system friction and weak stick centering. Landing at aft CG positions require more attention to AoA control than landing with forward CG. This is due to increased stick sensitivity and mild nose rise tendency at about 18 units AoA...."

From "Limited Performance and Flying Qualities Evaluation of the F-4E with the retrofit two-position maneuvering slat kit":
"Power Approach Configuration Evaluation
Longitudinal flying qualities were satisfactory but were adversely affected by low static stability in the 17 to 20 units AoA range. This region of reduced stability made precise control of AoA moderately difficult during landing approaches at 19 units AoA..."

Thanks for you answer,in reference of your two manual parts above, it doesn´t apply because I meant to maneuvers in clean configuration (no flaps/stats).

Alvaro wrote:The model has been validated by a F-4E pilot and no issues at this respect (Landing Configuration handling) were raised.

Yes! That was the 2 positive points I said in my post above."The good part in my opinion is the acft behavior after Take Off,stable,and in final approach"

But, ask him to perform a simple steep turn maneuver (FL100 with 250kt) or entering a flight pattern at 300kt reducing to 250 at downwind and check his opinion.

Regards,

Hamilton

Hamilton wrote: But, ask him to perform a simple steep turn maneuver (FL100 with 250kt) or entering a flight pattern at 300kt reducing to 250 at downwind and check his opinion.

<I did, and no objetionable behaviour was reported.>

300-250kcas is a quite narrow and low airspeed range where the slats will be surging around IN/OUT position (clean config, right?), specially if manoeuvering. Obviously, this will induce pitch transients. In the mid AoA range there is an additionally reduced static stability zone.

The lower the airspeed (dynamic pressure), the lower the stick forces (loose stick) and the higher the pitch sensitivity. This applies disregarding flaps/slats configuration. An AFT CG will only aggravate this pitch sensitivity.

Finally, engines transients will add an additional (not negligible) pitch effect.

In summary, below 300kcas the F-4E handling qualities can be considered anything but fantastic.

Alvaro wrote:
<I did, and no objetionable behaviour was reported.>

Well, I respect his (and yours) opinion, but I stand correct that this FDE needs to be improved.

Thanks

Ok