Hey friends - if I have the same freestyle drone, motors, and props, how will the length of the arms affect the flight characteristics of the drone?

Ultimately I'm trying to understand the advantages/disadvantages of a 5.5" capable arm length over standard 5.1"

on the same rotorsize, longer arms decrease the yaw performance qnd the performance of the quad overall. while it has a lower performance its not bad for cruising, its less nimble and has less reaponse -can "feel more stable" (not sure if that is a good description)
low wingspan can be more difficult to tune from their better performance.

it might not change a lot until you go for peak performance flights :-)

there is a trend to use 6inch arms in the rear and 5inch in front, all on 5inch rotors. the theory is more "clean air for the rear rotors.

on 5,5" rotors the quad might be less responsive but more efficiency.
personal i chose always as low wingspan as possible

Hug’s has explained this quite well and I prefer shorter arms for a nimble flight response/feel.

I'd add that if you're not increasing the girth (width and/or thickness) while you increase the length, all else equal, you are increasing motor vibrations.

(16-Oct-2021, 11:23 PM)hugnosed_bat Wrote: on the same rotorsize, longer arms decrease the yaw performance qnd the performance of the quad overall. while it has a lower performance its not bad for cruising, its less nimble and has less reaponse -can "feel more stable" (not sure if that is a good description)
low wingspan can be more difficult to tune from their better performance.

it might not change a lot until you go for peak performance flights :-)

there is a trend to use 6inch arms in the rear and 5inch in front, all on 5inch rotors. the theory is more "clean air for the rear rotors.

on 5,5" rotors the quad might be less responsive but more efficiency.
personal i chose always as low wingspan as possible

Is the assumption here that the props don't change size and only arm length?

"on the same rotorsize, longer arms decrease the yaw performance qnd the performance of the quad overall"
in here just about length of the arm

it sounded to me the op is looking for arm length change only, but maybe it was for the rotorsize change too

Every question has simple experiment.
Better to know empirically than hypothesize.

1. Get 10" frame. with 7" and 5" arms.
2. Fly 2306 motor 51466 with 5" arms AND bit extra weight... baseline.
3. Now swap to 7" arms.. 5" props.
4. Again with 10" arms.

5" to 5.5" is too small difference to probably notice.
I dont have 5.5" or even 3.5".. just 2.5, 3, 4, 5, 7, 9, 15

You will yaw much worse. Has more momentum, like skater with arms wide open. Likewise roll and flip will take longer to get to max deg/sec. But will feel more "stable".

(17-Oct-2021, 02:29 PM)hugnosed_bat Wrote: "on the same rotorsize, longer arms decrease the yaw performance qnd the performance of the quad overall"
in here just about length of the arm

it sounded to me the op is looking for arm length change only, but maybe it was for the rotorsize change too

you were right - I just wondered if I changed the arm size. for more background, I'm considering getting a secondary frame and Im thinking about getting something 5.5" so that I can run the gemfan 5552 for cruising at high speed, but also switch to something like the Gemfan 51433 or the F4s (5138) for freestyle without losing too much.

1/2" is not much difference. You will barely notice it.