(20-May-2022, 10:22 PM)Lemonyleprosy Wrote: I wonder what’s causing the wobble.

Maybe it would help if you could move the targeting camera more towards the middle of the frame so it’s more balanced?

I like floaty feel and stability of 5 to 8 blade props sometimes. Not so much for freestyle of course.

Looking forward to hearing how it flies on 4s.

Hi Lemony,

Since the wobble is only present at low throttle, I am thinking that the thrust is just not enough
for the weight of the quad which is over 300 grams with battery. A 4S will have more voltage
due to the additional cell even when draining down. So, I think it is worth a try before I go
changing things. I have a 4S 650 mAh strapped on, just waiting on the weather to cooperate.

The more that I work with this, the more I think that a fixed position for the targeting camera
will end up being better. With my current swing mechanism, I am able to lock in a position.
I am also working on a different, simplified, camera mounting option. 

When I look at the center portion of the frame, I can't see a good method of mounting the
camera. I will keep it in mind. Maybe I can fashion something. This thing is also very tail heavy, 
so I think keeping as much weight forward as possible might be best for now.

As for the props, I won't know for sure until I swap them out for something else with all
other things being equal. I have a set of quad-blade AVAN Scimitar props that I will try
next. That is the next change after I get in a 4S flight. 

Well, I took the Surveillance-1 out today with a 4S 650 mAh Goldbat battery.
This thing still has some wobbles. Not as bad and not as often, but still too
much for the intended purpose. On the positive side, I was able to bring
the quad down. 

The flight lasted about 4:47 minutes which is quite a bit less than the 
7:40 minutes with the 3S 1100 mAh GNB battery for about the same battery 
weight. This was expected and comparable to results with these two batteries
in other quads.  

Upon returning home, I swapped the hex-blade, turbine, props for a set of
Gemfan WinDancer Durable 4032-3 tri-blade props and charged up the 4S
650 mAh Goldbat battery. Ready for the next test flight.  

Hmmm just thinking aloud here but I'm wondering if the balance is off on your build because of the swing mechanism. I'm wondering if your PIDs on 3S are just not high enough to handle low throttle smooth movement. If this is the case (and holding your PIDs constant), I'm going to guess that is why you saw less wobble on 4S.

What are your current P and D? I'm assuming same for when you did 3S and 4S? Also, all default filtering?

For 4S I would try D=40 P=60 and for 3S D=50 P=75. Leave everything else I term, feed forward, and filtering default.

(24-May-2022, 01:33 AM)the.ronin Wrote: Hmmm just thinking aloud here but I'm wondering if the balance is off on your build because of the swing mechanism.  I'm wondering if your PIDs on 3S are just not high enough to handle low throttle smooth movement.  If this is the case (and holding your PIDs constant), I'm going to guess that is why you saw less wobble on 4S.

      Well, the balance could be off, however, it is to the rear rather than the front. This thing is 
      heavy to the rear. So much so, that I push the battery as far forward as I can get it just to
      put more weight forward and it is still REAR heavy. But then, it is DEFINITELY NOT balanced.

What are your current P and D?  I'm assuming same for when you did 3S and 4S?  Also, all default filtering?

       ALL of the tune is factory default. I have not changed ANYTHING at this point.

For 4S I would try D=40 P=60 and for 3S D=50 P=75.  Leave everything else I term, feed forward, and filtering default.

      I will definitely try these settings. Are the values the same for D Max and D Min 

Hi Ronin,

Thank you VERY Much for the tuning guide. I will try that. Are these settings the same
for all: Roll, Pitch, Yaw    I have attached a graphic of the current settings.

The FC is the JHEMCU GH743 40A AIO (whoop format) with GYRO=MPU6000, ACC=MPU6000

Betaflight:   BTFL 4.3.0  (assuming it is an RC, that info does not appear to be listed).

Since the Gyro is the MPU6000 unit, there should be no Betaflight issues, correct ??

Following my diagnostic methodology, I will do one more flight before moving to the tune.
I have just swapped out the props for a more traditional tri-blade so I want to give that a
try on the 4S battery. She is all suited up and ready to go. Next, I am on to tuning.

This quad is decidedly TAIL HEAVY even with the additional weight of the swing 
mechanism and the battery pushed as far forward as I can get it. 

Also, I am working on a different camera mount to replace the "swing" mechanism.
After flying this thing, I don't think that the swing is necessary. In fact, I am not sure
that I even need it straight down. I now think that a bit of forward angle might just
be better...and it doesn't need to move. Interestingly, this will "lighten" the front end
which will further bias the balance to the rear.

Again, Thank You Very Much 

2022-05-24   Test Flight at the Park

With the tri-blade props fitted, I am all psyched up. 3...2...1... Take off.

Success, NO wobbles. Very smooth and it isn't requiring much throttle.
It also isn't "sucking" battery juice like a shop vac either. Who knew.

The flight was very good.  At one point, I even flew using the targeting 
camera. I am getting more comfortable with it; kind of looked at the top 
of some trees.

A maintenance person arrived on a lawn mower so I cut that flight a 
little short. He was just passing through and I had some battery left,
so I decided to fly it again. Right after takeoff, the video became blurry,
then it was in and out. When the screen turned to snow, I disarmed so
as not to lose the quad. Yep, crash from about 50 feet or so. 

I found the disconnected MMCX video antenna about halfway to the quad.
Bad news. It must have hit directly on the left front arm as that arm is now
broken as well as the connecting stabilizer strut. Bummer. 

   On the positive side, both cameras are fine. No damage. 

Regarding the antenna, it was the MMCX connector that separated from the
VTX board. Yeah. Evidently these MMCX connectors are FRAGILE !!. 
NOTE:  I will have to glue the next one on and secure the antenna to a
standoff column...or...something. 

With a broken frame and a broken VTX, I think that I will take a break from
this build. In fact, I might as well get the actual Rescue Quad assembled and
just go for it. This fiddling around with a second quad is too time consuming.

So...I will put this one on hold and come back to it later. 

Hooray for no wobbles, but that crash definitely looks like it hurt.

You know. The only real damage from the crash is broken frame.
Everything else, including the cameras and the swing are survived
unharmed. So, I am impressed with that.

I have extra RoninUAV 4 inch frames so not big deal except the time
it will take to tear it down and rebuild.

Sorry to hear about Surveillance-1's untimely demise!

So it seems the hex blades' higher inertia, naturally slower speed for a given thrust, together with the pretty low AUW all conspired for too low an rpm at light throttle for sufficient torque out of the motors size and kv.

Hi Roteron,

Thanks.

Yes, I believe that is "technically" what was going on.  

The initial build was 330+ grams which, by my definition, is heavy 
for a 4 inch and those props are also pretty massive and likely harder
to spin. The motors were just not strong enough to pull everything at
the lower end of the throttle.

I was hoping for a bit more "low" end control with the hex-blade,
but it didn't work out in this configuration. 

The last flight weighed 303 grams AUW and was fitted with the
tri-blade props which are considerably lighter and have less pitch.

I do think that the hex-blade props might (??) be a little quieter,
but it was hard to tell since I couldn't here it unless I did a close
fly by at about 40 meters or so regardless of the prop. I haven't 
totally given up on them, but I will be returning to a bi-blade as my 
standard prop design.

The Motors: 
Since the hex-blade props in this size are 5mm shaft only, that 
dictated the use of a motor with a 5mm shaft. Both the motors
and the props for a 5mm setup seem to be a big heavier than
a comparable T-Mount drive train. I am not overly impressed
by the 5mm ones. Again, I will go back to T-Mount except for
some special build that requires props that are only available
with a 5mm shaft. Since bi-blade T-Mount props are now available 
in sizes up to and including 6 inch, that reduces the need for
5mm shaft motors. 

Although I have "parked" this build for the moment, I will rebuild
it {with some changes of course}, however, I need to move to 
the Rescue Quad and work on getting my Unsanctioned-1 back.

:highfive:

Flight Data:

303.1 grams AUW with 4S 650 mAh GoldBat Battery.

Total Flight Time:  8:27 minutes.   <-- Very Good. This surprised me. 

My guess here is that it was due to my very easy throttle. In fact, 
most of the flight was between 15-20 percent throttle and never got 
over 30 percent. With the higher voltage of the 4S battery, I was actually
using a lot less throttle to maintain the flight. Very Interesting.

2022-06-05        

The last crash broke the left front arm and stabilizer.

Since I need to get the Rescue Quad completed, I have 
dismantled this build and am moving the electronics to Rescue-1. 

I will rebuild it at a later date, but for now it is on HOLD.