Why am I gaining altitude in a turn?

[rktman]

Sorry for the confusion. I was assuming that the quad was moving forward requiring a negative pitch. Increasing pitch towards 0.0 will result in more vertical thrust resulting in an altitude gain.

Still confused.

How is it going forward with negative pitch? Unless it was going forward with positive pitch, the pilot wants to slow/stop/reverse, so reverses pitch to a negative angle.

In which case if the negative pitch angle is about the same as the positive pitch angle, there will be little to no change in height without any thrust changes.

I think the problem here is we're all talking about changes in attitude without specifying initial conditions. Will altitude increase or decrease as pitch/roll angles are changed, with or without throttle increase or decrease... The answer is, "it depends".

It depends on the orientation and relative motion (to the air, not the ground) of the drone when the attitude changes are implemented.

 

[rktman]

I believe the rest of my post beyond what you quoted shows I know what a coordinated turn is. But, more to the point is how can a FPV pilot know if the turn is coordinated. There is no indication about the alignment with the air stream. And, the accelerometer data is not displayed in the Fly app.

Let's reset -- sounded to me like you were getting a bit offended at being schooled, when you are obviously an experienced pilot. If so, I apologize, there was not a hint of that in my mind when responding to you.

Rather, I thought I was simply answering your question. The sorts of instruments and feedback we have in an airplane about aircraft attitude isn't necessary for there to be meaningful gain in coordinating turns, even if we don't have the instrumentation to do it perfectly.

And, practice can get you pretty good at it. I used my MA1 a few years ago to hone my coordination in turns, flying LOS in Sport over a nice big, closed (for decades) old airport in Scotts Valley (CA). Like anything, you get muscle memory for the relative position of roll relative to your yaw inputs to turn.

Finally, for our licensed pilots here, this got me thinking about side slips, cross-coordinated while landing fixed-wing in a strong cross-wind. Doesn't work the same on a quad, especially with the FC doing so much for altitude hold, but it does produce some interesting dynamics that, on the FPV, add some more "fun" to flying it. Meaningless on a camera drone with a 3-axis stabilized gimbal, for the most part.

 

[rktman]

Another way to look at is to consider the tilt angle with 0° being aligned with the Z axis. If tilt angle > 0° there is a loss of downward thrust resulting in an altitude loss. This perspective also includes the situation where the quad is moving laterally, i.e. along the Y axis.

Got it, but there's still a little confusion... In my best effort to analyze the physics, there's no distinction between forward/backward pitch, or left/right roll, insofar as the effect on vertical thrust (fighting gravity). Roll or pitch off of 0° and you will have to increase throttle to maintain altitude.

Similarly, go level (to 0° pitch and roll) and you will have to decrease throttle to maintain altitude (and not climb).

Is this right? Open question to all the manual mode flyers out there -- I haven't had the guts to put the FPV in manual yet -- still simulating on Velocidrone, but not crashing any more, and I can do a pretty decent job flying around and through things, do loops and rolls, even done 3 Immelmanns successfully.

I'm just too chicken to flip the switch yet on the FPV. Coward

 

[BudWalker]

Still confused.

How is it going forward with negative pitch? Unless it was going forward with positive pitch, the pilot wants to slow/stop/reverse, so reverses pitch to a negative angle.

In which case if the negative pitch angle is about the same as the positive pitch angle, there will be little to no change in height without any thrust changes.

I think the problem here is we're all talking about changes in attitude without specifying initial conditions. Will altitude increase or decrease as pitch/roll angles are changed, with or without throttle increase or decrease... The answer is, "it depends".

It depends on the orientation and relative motion (to the air, not the ground) of the drone when the attitude changes are implemented.

Maybe I don't understand what you are saying. But, for the quad to move forward requires the front to be lower than the back, i.e. pitch is < 0.0°.

Are you possibly referring to the control stick pitch? The values are reversed from the quad's attitude. A forward ctrl-pitch is > 0 which causes the quad's pitch to decrease. Likewise a backward ctrl-pitch is < 0 which causes the quad's pitch to increase.

 

[rktman]

Yeah, I was confusing. Let's simplify this by referring to a signless angle deviating from level in any pitch or roll direction. Doesn't matter.

When the drone is pitched or rolled away from level, some increase in throttle will be necessary to maintain altitude.

Starting already unlevel, after adjusting pitch/roll to get level again will require a reduction in throttle to maintain altitude.

Is that correct?

 

[BudWalker]

Yeah, I was confusing. Let's simplify this by referring to a signless angle deviating from level in any pitch or roll direction. Doesn't matter.

When the drone is pitched or rolled away from level, some increase in throttle will be necessary to maintain altitude.

Starting already unlevel, after adjusting pitch/roll to get level again will require a reduction in throttle to maintain altitude.

Is that correct?

?

The signless angle you're referring to is the tilt angle.

 

[Kilrah]

I'm not sure what coordinated turn means for a quad drone. I was providing both right ctrl-yaw and right ctrl-roll.

For a fixed wing AC co-ordinated flight means that nose is pointed into the air stream. (I can still hear my flight instructor hammering it into my skull that air flowing over the fuselage doesn't provide lift.) But that doesn't apply to a quad.

Basically your camera's lateral center being your direction of travel. If you only roll you just sideslip, gotta use yaw to turn and naturally you'll try to go "forward". But see below.

Yet people here, experience pilots, are saying the opposite -- reduce throttle when pitching forward and translating forward? I'm confused.

That's not what I said, I said reduced throttle while turning.

I've now done a flight where I was quite attentive to what I was doing, and as expected speed matters a lot. The climb/need to reduce throttle is simply due to improper control coordination, in your standard turn with roll and yaw you're actually slowing down. Like any aircraft you trade kinetic energy for potential one and vice versa, so if you slow down without reducing power you'll climb.
A properly coordinated turn that is done in a way to maintain speed requires you to also pitch down together with the roll and yaw, if you do that then you don't climb and don't need to reduce throttle, but it doesn't feel quite "natural" and from a very practical point of view isn't convenient becasue tilting down at that point makes you see the ground instead of where you want to go.

Most likely the guys who do racing have no problem maintaining their speed since that's what it's all about and they'll adjust their camera angle more towards aggressive tilt, but when you're caring more about the picture and align your trajectory/speed/angle for a nice "rule of thirds" view going forwards and go into a turn you'll naturally slow down and climb unless you reduce throttle as you're trying to maintain the view instead of the aircraft's dynamics.

 

[rktman]

That makes sense, @Kilrah thanks.

 

[BudWalker]

Basically your camera's lateral center being your direction of travel. If you only roll you just sideslip, gotta use yaw to turn and naturally you'll try to go "forward". But see below.


That's not what I said, I said reduced throttle while turning.

I've now done a flight where I was quite attentive to what I was doing, and as expected speed matters a lot. The climb/need to reduce throttle is simply due to improper control coordination, in your standard turn with roll and yaw you're actually slowing down. Like any aircraft you trade kinetic energy for potential one and vice versa, so if you slow down without reducing power you'll climb.
A properly coordinated turn that is done in a way to maintain speed requires you to also pitch down together with the roll and yaw, if you do that then you don't climb and don't need to reduce throttle, but it doesn't feel quite "natural" and from a very practical point of view isn't convenient becasue tilting down at that point makes you see the ground instead of where you want to go.

Most likely the guys who do racing have no problem maintaining their speed since that's what it's all about and they'll adjust their camera angle more towards aggressive tilt, but when you're caring more about the picture and align your trajectory/speed/angle for a nice "rule of thirds" view going forwards and go into a turn you'll naturally slow down and climb unless you reduce throttle as you're trying to maintain the view instead of the aircraft's dynamics.

Speed reduction in a turn is, at least partly, due to the acceleration because of the change in direction. In fact, given ideal conditions like no wind, etc, all of the speed reduction comes from overcoming the extra acceleration. The associated loss of kinetic energy isn't converted to the potential energy associated with altitude. Rather it's converted to the potential energy associated with the extra acceleration.

Consider a quad doing coordinated circles and maintaining altitude. That's accellZ > 1.0 g and both accelX and accelY = 0.0. The increase in acceleration along the Z axis (centrifugal force) has to come from more thrust. Decreasing throttle will cause a loss in altitude.

 

[PTMC]

I’ve just been looking for an excuse to use my new quad rotor descriptive definition:
Over Unity Thrust Vectoring Machine with Camera
Carry on, this adds nothing of substance to this discussion...?

 

[venomoussvt]

Well there you go.

You will never, ever, ever be able to hold altitude like the Flight Controller can.

EVER.

Glad someone said it before I had to.