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Holding Alttude

PostPosted: Wed Apr 20, 2005 2:59 pm
by Brown
I have a question for all pilots how do you hold altude because I have been taking rods lessons but my aircraft won't stay level on the instrument checkride I try trimming it . I can't keep it at 5000ft any opinons why .

Re: Holding Alttude

PostPosted: Wed Apr 20, 2005 3:01 pm
by Scottler
A) Checkrides suck.  Skip 'em.

B) Trim your aircraft properly and you'll be able to take your hand off the yoke entirely and maintain altitude. ;)

Re: Holding Alttude

PostPosted: Wed Apr 20, 2005 3:25 pm
by SilverFox441
The most common failure during instrument flight is "Riding the Guages". There is a tendency to try to adjust to quickly to what the readings are rather than let them stabilize...this magnifies control inputs and makes the problem worse.

1. Hand-fly the plane during trimming. Slowly adjust trim until you have no more manual input.

2. Remember that any power adjustment will affect trim. Hand-fly until speed is stabilized and then re-adjust trim as above.

3. Remember to "trim out" unwanted control inputs rather than trying to "trim in" wanted control inputs.

Re: Holding Alttude

PostPosted: Wed Apr 20, 2005 3:45 pm
by OTTOL
A) Checkrides suck.  Skip 'em.

probably the best suggestion.......I second that idea!


but.......if you're serious about it:

-most light aircraft will demonstrate positive dynamic stability about the lateral axis (pitch). What this means is that when it starts to descend, it will gain airspeed, the wing will then create more lift, and finally the aircraft will begin to climb again. The same goes with an un-commanded climb, with the values in reverse.

-What this means to the layman is that an aircraft which demonstrates positive longitudinal stability will maintain target altitude if it's trimmed properly. It will however require small control corrections due to dynamic factors.


I would practice just maintaining altitude, work on the other axes after that and then finally try and pull them all together with a smooth scan.
After you've practiced just the straight and level(maintaining alt. and hdg. ), go back and try the ride (although I can't guarantee success, as Scottler pointed out).
If you don't have this setup already, make sure you assign pitch trim functions to a set of buttons on the joystick. Trying to trim from the keyboard can be aggravating at best!
Once you've stabilized, "hands-free" at your target altitude, wait for the airplane to deviate from its pitch attitude and then a small nudge on the joystick should be all that is necessary to return to your altitude. If the airplane is trimmed properly, constant pressure, held until the altitude has been regained, will be excessive and actually aggravate the problem.  

Good Luck......

Re: Holding Alttude

PostPosted: Wed Apr 20, 2005 5:22 pm
by beaky
First of all, that default C172 doesn't trim out properly (assuming you're talking about the PP lessons). Try the RealAir C172 freeware model, it's much more true-to-life, IMHO.
http://www.realairsimulations.com/
Second, watch what the instructor does when he demonstrates levelling off, etc. You're allowed a little slop.
And yes, it is so true- don't "ride the gauges". Make an adjustment, then wait to see what she wants to do. If it's not what you're after, make a small change. Etc., etc.