Blackbird Sims / Milviz Forum Archive

I am not sure if this is a bug or by design. Since installing the ADV/TP to my F-4 J/S, the aircraft seems extremely hard to handle. On Takeoff it hikes the nose almost straight up in the air once the wheels leave the ground and on approach it is like a bucking bronco at 200 knots. I have the "Overall realism" slider on the F-4 failures screen set all the way to the left. Is it supposed to handle this poorly or am I doing something wrong?

Trim.

Take off: Try zero trim or a couple lines DOWN nose. It will still want to rocket once the wheels are off. Keep trying different trim settings until you are happy.
Landing: Trim UP. Real pilots report their helmet would be against the plexiglass looking at the runway and their gloves would wear off from working that trim button. Keep the ball lighted and you should be fine. Remember there's a reason why they used chutes to slow the thing up.

I've experienced the same thing; the NATOPS manual should speak to the need to have 3 or so units of nose down trim for takeoff. It is a matter of getting that correct for the weight/CG of the aircraft and then not over-rotating. After rotation you will still have to fight pitch-up forces until the slats are up. Be prepared to work the trim constantly.

This can't be accurate. I have so much nose down trim in it that the stick is half way to the forward stops and it still wants to sky the nose on takeoff.

Need to see the trim indicator on the forward left console. Secondly, you might have an aft CoG condition.

As you can see, it is taking a LOT of nose down trim to keep it under control.

I'm not a RW F-4 pilot, but this seem's a bit excessive to me. I'm not sure what you mean by an aft cfg. I did a clean install of both the F-4J/S and the ADV/TP this morning, so I know my installers are up to date. (A1.171220)

Padre_288 wrote:As you can see, it is taking a LOT of nose down trim to keep it under control.

I'm not a RW F-4 pilot, but this seem's a bit excessive to me. I'm not sure what you mean by an aft cfg. I did a clean install of both the F-4J/S and the ADV/TP this morning, so I know my installers are up to date. (A1.171220)

3 units nose down. That's the correct trim at liftoff, up to 200-250 kts.

Once the airspeed increases beyond 250 kts the dynamic pressure will move the stick back (through stab bellows) and a good amount of forward trim (nose down ) will be needed. The higher the acceleration the higher the nose down trim rate

Aft CG (>31%mac ) will significatively increase pitch sensitivity and additional amount of trim will be needed with speed changes.

(Please, take a look at ADV manual FAQs.)

Padre_288 wrote: I'm not sure what you mean by an aft cfg.

I meant CoG (or CG). Corrected.

And as Alvaro pointed out, the trim gets shifted by airspeed changes and you have to re-trim.

I know that lift is relative to airspeed. I just think that the amount of nose down trim required to keep it stable on takeoff is excessive.

Padre_288 wrote:I know that lift is relative to airspeed. I just think that the amount of nose down trim required to keep it stable on takeoff is excessive.

I am not talking about aerodynamics, I am talking about the Phantom Flight Control System itself, how it was designed and how it works.

Please, do read the ADV manual, TO-1 and whatever other technical reading you can get on F4 (a wide bibliography is included in the ADV manual)

Regards,

As you will find if you read the manual, the actual trim position (as indicated by stick position) shifts with airspeed change. Not talking about the required trim position.

I would read the manual if one were included with the ADV/TP package or available for download!

Manuals are available from the product page: http://milviz.com/flight/products/F4JSEXP/
A dedicated F4JS Tacpack manual is on its way.

http://milviz.com/flight/products/F4JSEXP/index.php

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