How to fix nose down attitude

[DaveQ]

I've been flying the Captain Sim TF-104G a lot recently and, despite having had it for about 7 years, I've only just become aware it flies with a noticeable nose-down attitude at transonic speeds at least. I seem to remember their B-52 was similarly afflicted and someone posted a fix which, again as I recall, was an alteration to the aircraft.cfg file. Can anyone remember what it was??

Thanks all

DaveQ

[DaveB]

That's an odd one Dave. The B52 should fly with a slight nose-down attitude AFAIK. It certainly looks that way IRL. Other than that.. I've always associated a nose-down happening when it's max cruise at alt has been exceeded. I don't fly fast jets enough but I know certain piston props will do this if you pump the volume up too much Reducing the cruise_lift_scalar is a 'dirty' fix but this may have consequences elsewhere in the flight envelope.

ATB
DaveB

[fsafranek]

Yep, a B-52 flying level is nose down. It looks weird but that's how the wing sits on the fuselage.

Sounds like you need to stay on the trim. Number pad 1 and 7 for up and down.

It's an older plane so maybe someone made some adjustments to the FDE to counter the effect. I haven't flown it in a long time but have been meaning to reinstall it.

[ratty]

Oh, boy! Dare I pontificate?

When the plane is designed, the wing is set at a particular angle of incidence relative to the longitudinal axis of the fuselage. In an airliner, for instance, the angle might be set to produce a level cabin at high-altitude cruise speeds. The faster an aeroplane goes in level flight, the lower the nose attitude has to be to counteract the greater lift. B-52s in nose-low level flight are just going faster than their design cruise speed.

I don't know your particular aircraft , but I can tell you that my A2A P-51 (one of the most realistically-modeled planes I've flown) has a distinct nose down attitude at high speed. If you're blasting around at the top end of the envelope, you might just want to refrain from looking at the outside.

Incidentally, I've found a few aircraft with alarmingly unrealistic nose-low attitudes, and cruise_lift_scalar seems to me the perfect parameter to tweak.

[Alky]

Incidentally, I've found a few aircraft with alarmingly nose-low attitudes, and cruise_lift_scalar seems to me the perfect parameter to tweak.

I find that the MJ C-47 flies with quite a nose down attitude, and it's certainly not fast. I'll have to play with the cruise_lift_scalar and see what happens!
Thanks!

[Dev One]

The only way I know is to slide the CL vs AoA graph to the right a little, just the centre bit of the graph where AoA is between +/- 3°. This can though affect the Cm vs AoA and drag, as it is calculated from ( I think) CL squared? (Anyone confirm that as I've forgotten a lot of my aero stuff I was taught!)
Don't forget also that as weight is lost - fuel burn & load dropping, then less lift is required & this therefore means less AoA required. Altitude too because of air density.

Keith

[thunder100]

CS 104 is a FS2004 model.

FSX as a tendency calculates the Center of lift a bit more backwards then FS2004.So if you use the FS2004 air file (CFS2 airfile even more so) you get a nose down tendency,but allready right from proper setting upon lift off(even if you trimmed it correct)

So what you can do as well in the aircraft.cfg is move the CG a bit backward

Thats not a F-104-->just an example

reference_datum_position=0.0000,0.000000,0.000000
empty_weight_CG_position=0.69,0.000000,0.000000
CG_forward_limit=0.17
CG_aft_limit=0.37

Best regards

Roland

[DaveQ]

Found the culprit. Me. Don't forget to retract the manoeuvring flaps above 400 knots..... What a dope!! I thought it odd I'd had the plane at least 7 years and never noticed it before.

But there was a thread about the excessive nose down on the CS B-52. Sure it normally flies nose down but (according to the thread as best I recall) not that much since it tended to land nosewheel first.

Thanks everyone for your advice

DaveQ

[DaveB]

The CS B52 was one of my MAJOR disappointments over the sale season. I don't think it flies nose-down at all.. even if you can get it to not go ballistic. Flew it twice.. left it alone. Thank god it was only $9/Euros.

ATB
DaveB

[delta558]

[QUOTE=ratty;933125]Oh, boy! Dare I pontificate?

When the plane is designed, the wing is set at a particular angle of incidence relative to the longitudinal axis of the fuselage. In an airliner, for instance, the angle might be set to produce a level cabin at high-altitude cruise speeds. The faster an aeroplane goes in level flight, the lower the nose attitude has to be to counteract the greater lift. B-52s in nose-low level flight are just going faster than their design cruise speed.

QUOTE]

The B52 generally takes off in a nose-down attitude: in certain configurations the rear wheels leave the ground first and at heavy weights it will fly along the runway with the nose distinctly down until speed is gained. It's a characteristic of the aircraft and your generalisation (which is commonly accurate,) does not always necessarily apply and certainly a B52 just after take-off is not going faster than its design cruise speed.

[ratty]

"a B52 just after take-off is not going faster than its design cruise speed"

True, but I think they take off with some flap, which could account for the attitude.