Trimming the P51

[Passero]

I always seem to struggle trimming the plane.

When I do a cold start, and put the P51 in the air I always have to trim the ailerons. It's always dropping one side of the wing...

 

If I take off with full tanks, I don't assume this is due to imbalance between the left and right fuel tank? Or is that 3 min taxi + takeoff so fuel heavy that it causes this imbalance so I have to trim it lot?

[Art-J]

Every MAP, RPM and airspeed combination requires different amount of trim, so assymetric fuel draw in Mustang is just one of the factors involved (although it doesn't help indeed) while trimming often is an ordinary routine in flying one of these birds until speed and engine parameters are settled.

 

That being said, quick tapping the trim key/button a couple of times rather than pressing it longer provides accuracy good enough for a couple of minutes of almost a hands-off flight.

[grafspee]

I always seem to struggle trimming the plane.

When I do a cold start, and put the P51 in the air I always have to trim the ailerons. It's always dropping one side of the wing...

 

If I take off with full tanks, I don't assume this is due to imbalance between the left and right fuel tank? Or is that 3 min taxi + takeoff so fuel heavy that it causes this imbalance so I have to trim it lot?

 

Don't use aileron trim. Use rudder trim. Keep fuel balanced by switching left right tank for even fuel level.

Most of the rolling tendency is created by asymmetrical prop thrust, gyroscopic precision, spiral slip stream and engine tourqe.

all of this counter with rudder trim.

Every speed change, every AOA change, every power setting change, will require rudder trim adjustment.

If you look close enough you will notice that vertical stabilizer is not aligned perfectly with fuselage, it is deflected to counter those things in cruise flight so you need almost 0 rudder trim in cruise.

Edited September 8, 2020 by grafspee

[DD_Fenrir]

The higher power and lower airspeeds associated with takeoffs result in torque effects being more noticeable - I suspect you'll be getting left wing drop, yes?

 

In this case, check your slip-ball - it's more likely your wing drop is being induced by flying with side slip so trim the rudder first.

 

You will find that as the fuel burns off from your left wing tank that you'll gradually have to start feeding in a little aileron trim after a while, but it shouldn't be significant.

[=475FG= Dawger]

My technique in the real world was to trim the pitch axis and use the rudders to keep the wings level when I needed to be hands off the stick. It works in DCS.

 

There are no airplanes that do not require constant trim adjustment.

 

That is probably the number one misconception that virtual flyers have.

[Lefty91]

You would agree though that student pilots are taught to fly with the stick, not trim..?

[Paganus]

Warbirds require constant trimming until you establish cruise conditions. If you think the Stang is bad, the Jug is worse.

 

Remember these are not just any airplanes. They are overpowered beasts.

 

In the P-51, never fly with all tanks full, unless you plan to be in the air a very long time. The 3rd tank behind the seat causes a center of gravity issue, and should not be used unless you really need the range.

 

Always start, taxi, and takeoff on the left wing tank. It is where the fuel return is so you need to make a little space there. If you are using the 3rd tank, switch to it once in the air, and drain it fully. After that, alternate from wing to wing. You don't have to switch a lot. The balance isn't really what is driving the need to trim. I doubt I ever switch more than 3 times.

 

Setup trim controls that are fast, and easy to access. You will be using them constantly. Trim the rudder to the ball before trimming the ailerons. Trim pitch as needed.

 

A good way to practice is to fly with just trim. Get stable in the air, and then try to control your flight without using the stick. This capability can really help later when flying heavy loadouts.

 

Good Luck!

[=475FG= Dawger]

You would agree though that student pilots are taught to fly with the stick, not trim..?

 

No one should ever use trim to maneuver the aircraft.

 

When I said keep the wings level using rudder I wasn't referring to using rudder trim. I was talking about pushing the rudder pedal with my foot.

[=475FG= Dawger]

 

A good way to practice is to fly with just trim. Get stable in the air, and then try to control your flight without using the stick. This capability can really help later when flying heavy loadouts.

 

 

This is not good advice. Fly with the controls.

[Paganus]

This is not good advice. Fly with the controls.

 

It's meant as a way to practice maintaining control of trim. It is not intended as a real world flight method.

 

This is a simulation after all.

[freemind_fly]

 

There are no airplanes that do not require constant trim adjustment.

 

 

Don’t say that. IRL I can fly a Cessna 172 well without. It’s a question of knowing speed and power settings.

Edited September 12, 2020 by freemind_fly

[shahin_sky]

Hi and sorry for my english

 

 

All the time my plane bank to the left and I can,t trim it so I try to zoom on the wing view and see what happend for the trim part

 

when u try to trim just the left Aileron trim tab moving and never u can move the right aileron trim tab on the right wing ...am I wrong ??? Is this a bug ? would u plz test this point and zoom on the left and right wings .

 

plz help me my friends

[shahin_sky]

DCS P-51D MUSTANG flight Manal Page 84

 

the trim tab on the right aileron is ground-adjustable

 

?????????????

[reece146]

Trim tab tuning (external, on ground bending of tabs) is not available in game for the P-51.

 

Some of the aircraft do allow you to tune via the special tab IIRC (Bf-109, Yak, others, IIRC).

 

For the aircraft that don't present this in the GUI you can modify .lua files but this is not recommended unless you know what you are doing.

 

However, this should not be necessary!

 

If the aircraft is not responding to trimming that makes me think that you have "noise" in your controls either from :

 

• having a bad device (joystick potentiometer worn),
  
• conflict with another device (e.g. same axis bound on joystick and a car steering wheel) or,
  
• the axis is not originally centered at game start up.
  

The P-51 in DCS is probably the easiest warbird / taildragging aircraft in DCS to get trimmed at steady-state attitude, engine settings, and speed.

 

 

HTH

[Shahdoh]

Hi and sorry for my english

 

 

All the time my plane bank to the left and I can,t trim it so I try to zoom on the wing view and see what happend for the trim part

 

when u try to trim just the left Aileron trim tab moving and never u can move the right aileron trim tab on the right wing ...am I wrong ??? Is this a bug ? would u plz test this point and zoom on the left and right wings .

 

plz help me my friends

 

 

As stated earlier, on prop aircraft, when available, trim RUDDER first to center the ball. This is particularly true with the Mustang. I rarely have to trim aileron in the mustang unless there is an uneven weight distribution issue or damaged wing.

 

PS: And on aircraft where rudder trim is not available, input rudder to center the ball.

[grafspee]

As stated earlier, on prop aircraft, when available, trim RUDDER first to center the ball. This is particularly true with the Mustang. I rarely have to trim aileron in the mustang unless there is an uneven weight distribution issue or damaged wing.

 

PS: And on aircraft where rudder trim is not available, input rudder to center the ball.

 

Exactly, aileron trim is only useful if your plane has significant lateral unbalance, If not any left wing drop is due to engine and propeller, so use rudder trim.

[Passero]

And right wing drop? Fuel imbalance? So in that case, aileron trim would be useful while the fuel balances out?

[grafspee]

And right wing drop? Fuel imbalance? So in that case, aileron trim would be useful while the fuel balances out?

 

Right wing drop is due to over speed or over trim(if you trim rudder right too much right wing will drop), vertical stabilizer in p-51 has small angle of incidence which counter some part of this, but at high speeds this require opposite rudder trimming.

It could be as well due to left tank being empty, while right tank remain full. If pilot forget to keep tanks in balance. But this require quite a long time of flight to happen.

It is pronounced quite visibly while doing some ground attack run, when you gain a lot of speed in dive if you dont react with rudder inputs, p-51 gains extreme side slip.

This wing drop left or right happens due to side slip, if your plane side slip is to the right part of right wing is covered by fuselage thus reducing right wing lift force, so right wing deeps down,

Why plane would side slip at all, for example one of the reasons is asymmetrical prop thrust, when plane fly slow it require high AOA, then when you apply high power setting at this stage for example steep climb, right side of the prop pulls harder then left side of the prop so plane will side slip to the left and left wing will drop down so you need to apply right rudder to avoid side sliping and the wing will not drop anymore.

There are 4 thing which impact this.

P-Factor = asymmetric thrust

Gyroscopic precession

Torque effect

Spiral slipstream

Edited September 13, 2020 by grafspee

[=475FG= Dawger]

It's meant as a way to practice maintaining control of trim. It is not intended as a real world flight method.

 

This is a simulation after all.

 

Its not good advice for this simulation either. It is not what trim is for and teaches an entirely incorrect method of application.

 

In an actual airplane you displace the controls then use the trim to hold the controls in the displaced position.

 

Displace the controls to the position of need then use trim to correct out the displacement is how you properly trim in DCS.

 

Do not use trim to change the aircraft attitude. Try to simulate being a pilot.

[=475FG= Dawger]

Don’t say that. IRL I can fly a Cessna 172 well without. It’s a question of knowing speed and power settings.

 

Every trim setting has a power and speed combination that results in a "trimmed" aircraft. Sometimes there are more than one combination of power and speed that "works".

 

However, every change in power, speed or attitude requires an adjustment of trim in order to relieve the control forces the pilot must input to maintain the desired attitude.

 

Thus, every aircraft requires trim adjustment for every change in the flight conditions, which generally occur quite often except in cruise flight.

[=475FG= Dawger]

When I fly the DCS P-51 I do not touch the aileron or rudder trim. I leave them centered. I use rudder pressure with my foot and stick deflection as necessary.

 

There is very little to no torque effect above 100 mph in the DCS P-51 and fiddling with the rudder and aileron trim in your average combat mission causes more trouble than it resolves.

 

However, if you are doing something that requires (relatively) long periods of non-maneuvering flight, the rudder and aileron trim become more useful.

 

If you are just learning the P-51, center them and leave them alone. Learn to fly the airplane with the primary flight controls first.

[Passero]

I did try now a few times without using aileron trim and trimmed with rudder instead. Seems to work fine.

 

I initially didn't understand that the right wing drop could be countered by rudder. My initial instinct was to use aileron.

[freemind_fly]

Every trim setting has a power and speed combination that results in a "trimmed" aircraft. Sometimes there are more than one combination of power and speed that "works".

 

However, every change in power, speed or attitude requires an adjustment of trim in order to relieve the control forces the pilot must input to maintain the desired attitude.

 

Thus, every aircraft requires trim adjustment for every change in the flight conditions, which generally occur quite often except in cruise flight.

 

And I can tell you from experience that knowing the right power settings and having your attitude under control you can fly a 172 with minimal trim. e.g. level attitude and 2300-2400 will deliver you cruise speed without overly strong forces you need to trim away. The same goes for pattern attitude speeds and flap settings - its a question of knowing the exact numbers by heart and not fumbling around to much. But I had a very good instructor.

 

Its different for a warbird like the P-51D but the 172, as a trainer aircraft, is very well balanced.

 

 

There is very little to no torque effect above 100 mph in the DCS P-51 and fiddling with the rudder and aileron trim in your average combat mission causes more trouble than it resolves.

 

However, if you are doing something that requires (relatively) long periods of non-maneuvering flight, the rudder and aileron trim become more useful.

 

If you are just learning the P-51, center them and leave them alone. Learn to fly the airplane with the primary flight controls first.

 

Thats the key point here.

Edited September 13, 2020 by freemind_fly

[Glide]

I believe even the guides teach standard ops is 5 degrees of rudder trim for the P-51 takeoff.

[=475FG= Dawger]

I believe even the guides teach standard ops is 5 degrees of rudder trim for the P-51 takeoff.

 

In the real airplane, that 6 degrees is supposed to give you a properly trimmed rudder during the initial climb. It is in no way meant to provide adequate rudder deflection during takeoff.

 

In the DCS P-51 the 6 degrees is unnecessary and most probably counterproductive. A half toe of rudder is all you need once above 100 mph.