Tilting arms upward: disadvantages?

I know that tilting drone arms upwards used to be a crutch for crappy flight controllers, and is frowned upon now. But are there any disadvantages? What if you had other reasons for tilting upwards slightly such as structures or downwash placement, what would be the cost for tilting arms upwards?

@Leonardthall for vis (as he has posted about tilting arms specifically before)

As mentioned many times on the forums, losses in efficiency due to wasted thrust

You can easily calculate the exact amount of wasted thrust with only a little trigonometry
For a single motor [Wasted Thrust] = Sine(tilt angle) * [Total Thrust]

Again this is a design choice that depends on your priorities for the goal you want the vehicle to achieve.

uhhh… I was assuming people knew principle behind small-angle approximations…

Your formula is wrong…

Wasted thrust = (1-cos(tilt_angle)) * thrust

for 5 deg tilt it is 0.38053019 % which is pretty negligible and worthy for a tradeoff…

so i was asking about control tradeoff, etc… thrust loss is easy and everyone knows that…

Haha… my bad, thanks for pointing it out
I mistook the tilt angle as the angle by which the thrust vector is tilted, whereas it should be the angle by which the arms are tilted

And speaking in terms of control there no tradeoff, it’s the opposite. Tilted arms can achieve a stable open loop PID control for small displacements.

Hope this helps

… its the same, sine of tilt angle framed in any way would be wrong.

thats my guess, it has no disadvantage.

I’m trying my best to explain

Screenshot 2022-05-14 004745

Does this work ?

no. that is horizontal component that was not present before. what is wasted is what is subtracted from the VERTICAL component, which is F - Fcos(angle).

e.g. F does NOT equal Fsin(angle) + Fcos(angle)

ohhhhh… Now i get it. You are right, im sorry

So the wasted thrust is the difference between non-tilted vertical thrust and tilted vertical thrust
and not the side thrust that is being canceled by the opposite motor
This was so obvious !!!
I don’t know how i missed this :man_facepalming:

The main problem is increased sensitivity to wing gusts and increased power required to hold a lean angle at speed.

i suppose the gust sensitivity comes from differential inflow, but why is it less efficient in forward flight?

Because it wants to lean away from the wind. Holding against that requires extra power.