Changing the in-flight cruise angle...

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Rallymodeller

Rallymodeller

Charter Member
Might be an engineering issue, but I'm not sure so I thought I'd ask those more knowledgeable with configs and FDEs than I.

Flying some propliners, they seem to take on a pronounced nose-down angle. Having just finished a flight with Jens' Avro Tudor IV, at above 170kt the nose starts to point pretty severely down, until at 200kt it seems to have about a 4°-5° nose-down angle. As far as I can determine, this is not correct and it also looks really irritating. Is there some way to change this, i.e. by altering the wing angle of incidence?

Considering the normal cruise speed of a Tudor IV was 245kt, having the nose pointing 7°+ down at cruise might have an adverse affect on in-flight catering...
 
What altitude were you cruising at? Severe nose down trim usually means you're too low for the speed you're trying to achieve.
 
Try 12000 ft or higher, the Tudor was pressurized so no reason for it to stay low and was probably designed for med to long haul routes where high=faster.
 
Considering the normal cruise speed of a Tudor IV was 245kt
Click to expand...

Also, keep in mind that 245 knots is most likely the Tudor's typical true airspeed (TAS) in cruise ....not indicated airspeed (IAS). In other words, if you're trying to push the Tudor to read 245kts (IAS) on the airspeed indicator, you're probably going way too fast....which would necessitate excessive nose-down pitch to maintain a constant altitude.

Air density decreases with altitude, which causes IAS to decrease as well...even though TAS actually increases if the same IAS is maintained.
 
In the airfile what you are looking to change is the AoA entry. Angle of attack I think is what that stands for.
 
If you are not into air file mods, you can try changing this statement in the aircraft.cfg in the Flight Tuning section. Changes of .1 increments = 10%.

[flight_tuning]
cruise_lift_scalar = 1
 
But you almost certainly are traveling way too fast at too low an altitude. At 18,000 ft 245 kts TAS means that you should be reading about 198 kts indicated airspeed. At lower altitudes (i.e. below the design altitude of the plane), it *should* be nose down if you are trying to reach 245 KTAS, since it was designed to fly higher.

Hope this helps,

Tom Gibson
CalClassic Propliners
www.calclassic.com
 
Thanks for all the replies, folks. I see now that I was maybe pushing those Merlins a little hard below 10K. Just because a plane CAN do it, doesn't necessarily mean it SHOULD do it. One of the things I am having to get used to in my 1960s FS environment is just how long it takes to get from place to place. When you are used to clipping along at M 0.78 at 40,000' doing 190 kias at 10,000' feels like I could get out and walk.
 
There are a couple of tables in the air file that affect this, one is the Lift vrs AOA curve. One can actually find the lift curves for most airfoils and do a pretty close job on this, but the usual reason as Milton has indicated is that the lift is off. However if you are pointed nose down at speed, probably generating too much lift. So a reduction of the overall lift in the cfg file would make the plane tend to have a higher attitude at all speeds.

Good Luck! T
 
As pointed out by Tom and others there is nothing to fix in this case, except for the squishy biological interface behind the yoke.
Instead of trying to "tweak" and FDE to behave as desired when the aircraft is used incorrectly in this case the pilot needs tweaking to understand what can and can't be done with these aircraft.

It makes not much sense to backdate FS to be able to fly Tom's Doug's or our Connie's and then treat them like a 737 or a 172. They are not and they were not supposed to be.
As a matter of fact a lot of time was spent to make them behave realistically in all phases off flight. That means, for example that they can't climb to their service ceiling directly after a MTOW departure. They can't fly a modern slam dunk approach because you won't be able to slow down to Vfe or Vle.
You also can't just firewall the throttles and leave them there until BOD....at least in the Connie's that will get you a certificate in the triple tailed glider club.

And just for completeness sake if you push a 747 to fly at 90% of Vne at 8000ft I am quite sure it would have a decidedly nose low pitch attitude as well. Nothing wrong with that FDE either. It's simply physics.

Stefan
 
I'd have to agree here too. Having just flown this wonderful bit of vintage aviation, Jens obviously spent the time fussing to get her to fly like the real thing. The only quirk I found was the main tires sank a bit too far into the pavement, but I didn't try it on a default airport either. Very nice addition for my hanger, thanks for putting her on display. And thank you Jens.:wiggle:
 
and especially DC-6 fly a little nose down in FSX(FDE FS Aviator unquestionable correct) and even in reality.

This has to do with lift point vs CG

my 2 cents with some experience on that

Roland
 
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