Questions tagged [trim]
Trim tabs are small surfaces connected to the trailing edge of a larger control surface on a boat or aircraft, used to control the trim of the controls, i.e. to counteract hydro- or aerodynamic forces and stabilise the boat or aircraft in a particular desired attitude without the need for the operator to constantly apply a control force. This is done by adjusting the angle of the tab relative to the larger surface.
89
questions
1
vote
1
answer
245
views
A220 Direct Law Mode trim control
When A220's PFCCs are all failed, the airplane enters direct law mode.
In this mode, from description, pilots should manually control stabilizer trim.
When this situation occurs, does pilot need to ...
- 401
4
votes
3
answers
834
views
Why does elevator trim hold a given airspeed? [duplicate]
I'm trying to understand a principle described in the book Stick and Rudder by Wolfgang Langewiesche between angle of attack and airspeed in relation to the elevator trim. He states that as angle of ...
- 297
2
votes
1
answer
412
views
Do the trim wheels on the Boeing 737NG move by themselves during the takeoff roll?
After the stab trim is set before take off, will it move by itself during the take off roll? If yes, why? Where can I find the reference?
- 21
5
votes
3
answers
1k
views
Could a trim system conceivably manipulate only primary surfaces?
Most airplanes' trim systems manipulate a tab associated with a primary surface. For example, a pitch trim tab (secondary surface) is attached to the elevators (primary surface) and will change the ...
- 1,667
5
votes
2
answers
979
views
Do aircraft have backup systems to trim when they don't have trim wheels?
What happens if the motor that trims the elevator of an airplane fails and there are no trim wheels in the cockpit (like in the Boeing 747). Is there a backup system or hidden trim wheels?
- 153
0
votes
2
answers
2k
views
Could the pilots really not trim manually to overcome MCAS, as shown in the Netflix Downfall documentary?
In the recent Netflix documentary, a claim is made that once MCAS activated, after several activations, the pilots physically could not trim the aircraft due to the speed and pitch.
Is this true? I ...
- 13.6k
4
votes
2
answers
410
views
Can I assume that aoa on horizontal stabilizers correspond to aoa of the main wing?
I am in the process of designing a small wing (Re ~ 50-100k) and am wondering if given (a) the Cm on the main wing is relatively small at low aoas, (b) the horizontal stabilizer will produce lift as ...
- 227
1
vote
2
answers
159
views
Trimmed unstable aircraft [duplicate]
I am wondering which conditions are possible and what they mean:
Aircraft is statically stable in pitch and there is a trim point (for a specific surface deflection)
--> So in this situation my ...
- 11
15
votes
3
answers
4k
views
Best way to correct for plane's natural tendency to turn left?
I am a new private pilot in training. I've only had about two hours of flight lessons so far, so I'm still quite new to this.
In a single engine, PA-28-181 Archer, I found that the plane has a natural ...
- 1,137
7
votes
6
answers
3k
views
Is a trimmed flight not always an unstable system?
As soon as I am flying in trimmed flight condition, my pitching moment around the center of gravity becomes zero. So my center of pressure has to be located in the center of gravity, so that there is ...
- 71
5
votes
1
answer
1k
views
Why do most aircraft with variable incidence tailplane have the possibility to trim much more degrees for nose up than for nose down?
Probably the question will be a little bit confusing but I'll try my best to make it clear.
Due the position of the CP with respect of the AC, symmetrical airfoils don't produce pitching moments, but ...
- 51
6
votes
3
answers
3k
views
Why doesn’t the A320 have any provision for manual aileron trim?
To eliminate the need for pilots (human or automatic) to maintain continuous force on their aircrafts’ yoke/joystick and rudder pedals while flying, aircraft generally have some sort of trim mechanism ...
- 28.4k
3
votes
1
answer
1k
views
Why is the CG envelope wider when the aircraft is heavy?
I mean, the same aircraft, but empty or on MTOW. According to MAC, those limits are the same, but the indexes are different. So if I understand that correctly, the CG can be more forward when the ...
- 31
2
votes
2
answers
120
views
What happens without trimming a statically stable aircraft?
if I have a statically stable aircraft, it will always return to its neutral position. What happens now if I do not trim my aircraft? Will it move/osicallate around its neutral position and be ...
- 21
0
votes
2
answers
693
views
On large aircraft, why do flaperons not run the full length?
This is a 777 flaperon. It looks rather tiny, compared to the flap.
There have been air disasters where the airplane rolled uncontrollably for one reason or the other. It seems to me that a larger ...
