Beagle Pup experiment

[IAHM-COL]

@bomber

It is not my joystick. It is the plane.

I can't trim it and then leave it alone to a safe straigth flight.

Here you have an screenshot to a hud showing all the wing surfaces are well alligned. the speed is descent. The plane persists in rolling and spiralling away, unless I start dancing with rudder and ailerons to keep it straight



To control for an uncallibrated joystick I did this test over a mouse only.
Same result as stick.

[SHM]

FGM, FGM NON-GPL,

FGMembers

[bomber]

I've just spent the afternoon taxiiing and had no problems ..... If I had one criticism it's that it starts to roll at idle when if I was designing the frictions on the wheels it wouldn't..

I'm looking at the gear frictions at present yet nothing I do seems to change this.

[IAHM-COL]

confused....

[sanhozay]

all the wing surfaces are well alligned. the speed is descent. The plane persists in rolling and spiralling away, unless I start dancing with rudder and ailerons to keep it straight

This is as expected. When the ailerons are neutral, the inertia of the propeller (which is spinning clockwise), generates an opposite force on the aircraft and it rolls to the left. This is a very light aircraft with a fairly standard propeller so the effect of propeller torque should be more noticeable than on some other light singles. (Empty weight of 985lbs compared to 1500lbs for a C172P, for example).

In my FDM, you can counteract this tendency with aileron trim but not on Bomber's because aileron trim is not implemented. Bomber's is more correct because the real aircraft doesn't have aileron trim tabs. My FDM has aileron trim because Aeromatic++ gave it to me and I use it in the autopilot (which the real aircraft didn't have as standard either).

My longer term plan was to make aileron trim a user preference so if a pilot wants to be more authentic and fly without it they can. Elevator trim exists on the real thing and will be adjustable from the cockpit/joystick as usual. Rudder trim is a preset tab on the back of the rudder and I'll probably make this so that it can be set to a fixed value while on the ground but not changed in the air. It's not present on all Pups but doesn't seem to be model-specific.

[IAHM-COL]

ok.
testing again.
Lets see if I can get it to fly stable with this new info.

[bomber]

I think what you're experiencing is engine torque.... it's normal

[edit]

thanks sanhozay I was away testing and then posted but you'd beat me to it..

[IAHM-COL]

Ok
This maybe start getting some sense

@bomber, @Sanhozay

If I use the mouse I can center my aileron and my elevator slightly off-axis, and I can let the plane flight in a safe nice climb with stable straight path (and again, as I said before, I love the reaction of the plane in the air, its gentle and obedient, with good response to wing surface deflections)

image a



Now, if I press #5 in keyboard, centering all my axis, then hell brakes loose. (due to not having any trim set, off course) the prop wash takes over laterally and the roll I get is serious business.
Notice the elevator position too in image b below. As I center elevators without the trim, then my plane gets on a real climb-climb-climbnow attitude until I can't anymore (airspeed drop, drag increase) and I get a nose down attitude on the left roll.
It does not fall from the skies. It just gently rolls and spins (really must make video)....

image b


So here's the thing.

1. Per Sanhozay the aileron trim is unrealistic to expect here. Ok
2. Is the elevator trim also a dream of FG pilots that RL dog-fliers dont enjoy?

This means, that the pilot is married to push and pull the yoke to get a level flight.

My joystick centers itself. Unless I keep deflecting. That's why I have exquisite flying control on the stick, but I must keep pushing and pulling right or the plane behaves as described above.


Question #2/ Elevator trims?

[IAHM-COL]

If my test results and comments are very noob. I apologize.
This is because I am very noob. I know much nothing on FDM implementations. (trying to help within my limitations)

[bomber]

Ok here the interesting thing with regards to this engine roll torque....

As a designer of a plane I can do some crazzzy stuff.. I can use a bit of rudder trim to counter this roll... I could tweak the whole of the rudder to one side, and then give you adjustable rudder trim control in the cockpit.. or I could make the wing airfoils ever so slightly different on the left wing to the right wing and thus cancel the roll out that way..

The thing is I don't know which one of these the actual designers did, if they did anything at all.

But on some planes they certainly did one of the above.. but it doesn't get rid of it, it just changes at what speed this effects you...

Most of the time what you're looking for is a smooth torque free landing... it's that rushing towards the ground with the plane rolling on you that can make it a hairy experience.... So you look to cancel out the engine torque at idle or just above whilst doing 50kts.

But if you do want this on your plane... when you're doing 120kts the left wing will generate more lift than the right and you'll roll to the right.... so maybe you want the plane to be trimmed at cruise speed, 75% power ?

The thing is.... when you start doing flight models correctly, these are the questions that start getting asked...

So I'm happy as can be.