Weight vs Lift

Kilby

Active Member
Hey Gang,

What do most of you use as a formula for total lift compared to total weight on your builds? I just finished up a HL quad that is flying a little funny, and I suspect it's actually over propped or simply has too much lift. In short, it's got a total of 21 lbs of lift and weighs in at 8.5 lbs. It's using a Wookong, 4014-11 motors, Tmotor 35a sec's and 16 inch props, but when I take it out I'm getting some "jumping" effect in the vertical. It just sounds like it's over compensating for altitude adjustments. It's possible that the same issue exists in other directions, but it's most pronounced in the vertical. Also, it REALLY doesn't like the wind. Even the slightest of breezes pushes it around like a little chump!

Thoughts? Am I massively overpowered here? My next two steps in testing involved moving down to a smaller 15 inch prop as well as adding 1 lb of weight. Any wagers on what does/doesn't work?

-Terry
 

kloner

Aerial DP
quad/hex/octo?

sounds under gained and possibly too low of throttle at hover.... we shoot for 40% min in manual at hover.... less than that and it's like leaving a stoplight in 3rd gear. you will remain more efficient the lower you can keep that hover throttle and keep control.... that's how we do the discos

lift it up in manual and see or have somebody tell you where the stick sits hovering..... both fixes you mentioned do the same, loads the disk and should increase the throttle at hover
 

Kilby

Active Member
Thanks, Steve. I hadn't thought of checking the hover point in manual. I'll do that in today's tests. If you had to guess, what would you say a rough gain structure would be? I started it at defaults and initial tests showed it getting a little worse as I raised them, but thinking back, that could have been more as an effect of the throttle being to low at hover.
 

kloner

Aerial DP
I usually put them on a dial and start sweeping through... it'll go from loose to locked in to oscilating then back to the highest point i can get it, then i'll break away the gains that look like they still need tuning and take them off a knob, leave the offenders, start sweeping through gains, etc.

wind is gonna be the key to actualy tuning it so get back in it.

nazas usually are 120-140 in the basic row, 80-100 in atti mode on stuff i fly,,,, every once in a while i can get them higher but that's a pretty close start..... once they look good, if problems persist alot of times it's a mechanical thing like bad new motor, un balanced prop, etc.
 

Kilby

Active Member
Thanks for the input. Just ran out and picked up 15 inch props, so testing continues. On a side note, I found a shop not far from my house that stocks this stuff now. That's a first. I have to admit, it was nice to be able to leave the house and come back with props instead of ordering them.

I'll post up when it's tuned.
 

Kilby

Active Member
That did the job, kloner. Added about 1lb and moved down to 15 inch props and it flys great now.
 

gtranquilla

RadioActive
Kilby,
Also if you have the time, run your design thru eCalc for Multirotors. It provides valuable insights as to the effect of undersized or oversized props etc.

Also the ratio of your total AUW to your maximum thrust is, I believe, your disc loading.
Disc loading is a similar concept to wing loading for fixed wing planes. If disc or wing loading is too light, the efficiency may be excellent but your aircraft will bump around in the wind quite a bit.

Great choice of motors by the way.
 
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