Aircraft "porpoising". Why?

[+DoctorQuest 125]

Disregard for the moment. I may have found the issue. Need to do some further research.

Edited January 30, 2013 by DoctorQuest

[+SidDogg 130]

...probably the pitch moment, dude.

 

 

 

 

 

SidDogg

[+RAVEN 414]

Is the Aircraft a jet or a prop?

[Panama Red 22]

How much "lift" do you have in your stabilizers ???

[+DoctorQuest 125]

Ok. After experimenting for a while it feels like the pitch trim is cranked way up. I try to level the A/C but it insists on pitching up regardless. So, yes, it feels like a problem with the horizontal stabilizer or the elevator.......

 

Is the Aircraft a jet or a prop?

 

Jet.

[+RAVEN 414]

Sorry ,If it was a prop you can set "ThrottleRate=1.0" and it reduces porpoising.Don't know if this helps you?

[+DoctorQuest 125]

Tell you what. I found a very similar a/c that seems to fly right. Let me poke around the data.inis......... They are very different in respect to stabilizer values. And they are supposedly both "SF2" FMs.

[Panama Red 22]

If it is porposing while using the AI, you can also check to see if your "Cruise" speed is 76% of your Max speed. Otherwise it will "hunt" the proper speed to stay level, at 76%, it stops the hunting.

 

Each plane's stabilizer lift numbers are specific to that plane. Just because one set of CL0 numbers are good for one plane does not mean that they will work for another. Try lowering the CL0 number until the porposing stops.

[Fubar512 1,350]

Another tip is to set the HUD in debug mode, and note the Mach level where the porpoising is at its worst. You then add the following declaration under the "flightcontrol" section of that aircraft's data.ini:

 

AutoTrimMaxMach=X.X (where X.X is the aforementioned Mach level).

Edited January 31, 2013 by Fubar512

[+DoctorQuest 125]

Great suggestions! Thanks!

[+VonS 1,424]

Gentlemen,

 

Would the same tips work to minimize porpoising of aircraft flown by AI in First Eagles 2? I suppose it doesn't hurt to try.

 

Happy flying,

Von S

[+Dave 2,322]

Were they doing it on porpoise?  Tell them to straighten up and fly right!

[Do335 382]

If it is porposing while using the AI, you can also check to see if your "Cruise" speed is 76% of your Max speed. Otherwise it will "hunt" the proper speed to stay level, at 76%, it stops the hunting.

Panama Red this is interesting, I wonder which aircraft you are referring to, is it possible that it has a limited top speed and quite a high stall speed, so if cruise is set too low it is forced to do stall recoveries?...

I did some cruise speed streamlining on the korean era planes. Most of them were initially too slow, so bumped it up to 70% but that made it hard for AI to score gun kills. I settled on 65% atm.

[+VonS 1,424]

This is turning into a stimulating conversation, on an old post - nice to see some life in it again. The porpoising in First Eagles 2 usually happens when aircraft flown by AI are being chased or are chasing another plane - fast oscillation, up and down, of the elevators. I'll see if some of the tips here help with that. Peter01 posted some tips on this a few yrs. ago in the FE2 discussion list but none of those tips seem to get rid of the porpoising. I've got the cruise speed set on aircraft to 90% of top speed in FE2 - maybe this is the problem...will report back if I find something that works.

 

Happy flying,

Von S

[Do335 382]

ooops, didn't notice the posts' time stamps... eehh:D

[+VonS 1,424]

Just a quick follow up that tweaking of cruise speed in FE2 doesn't stop the porpoising... throttle rate also isn't the problem in First Eagles 2, tweaking of elevator and rudder turns does fix things - will post more info. in the relevant forum.

 

Happy flying,

 

Von S

[+EricJ 4,254]

Having done a lot of DACTs I just assume they're trying to force an overshoot while doing that.  I've seen the same plane porpoise (on porpoise)  and fly normal given different flight regimes, or during different states.  It really could be something but that's how I approach it anyway.