Another day, another flight report. I got the prop locks in and decided to try them with a tweak to the aircraft.
First, some background.
Someone on Youtube (and I think in this thread!) saw my videos where I had jello in the day and by looking at the props suggested my arms were coming loose. I was seeing jello on bright days, even when I applied a stronger 3-stop ND filter. I was convinced I needed even a stronger filter, but given the late afternoon light as well as other's much brighter daytime videos, this made no sense sometimes.
Looking at all my flights, where I got jello it looks like the arms were shuddering in a kind of harmonic vibration: the same kind of vibration my P2 H3-3D gimbal had before I applied sorbothane. The arms sometimes shudder and wobble causing a visible harmonic shake that leads to jello. It is not noticeable at night or sunset due to the slow shutter, but I can sometimes see it in the bright sun during FFF and even in hover sometimes.
Now most of my flying has been in low light so far. So I haven't seen much of it. The vibration on the arms is still sometimes noticeable in those flights too when you look at the motors and props with the camera but the slow shutter evens it out on footage. My few bright sun flights had jello both in hover and in FFF, and in each case when I looked at the motors and the arms... they were shuddering while the rest of the craft was relatively stable. The harmonic shaking in the arms was noticeable on camera (when I aimed at the motors to see) whenever I had the issue in calm winds. Like
Alessandro mentioned, it's not all the time, but enough to notice.
Not every moment of every bright sun video I filmed (all 3 of them) had this, but most of them did in FFF.
Today, I checked the arms on the ground. They were noticeably wobbly on both sides. The motors shook easily. I applied a temporary fix that was suggested by Rob here inside the T-joints by adding a little rubber to the existing rubber to help the compression clamp grip better (but not otherwise tightening any bolts), which ensured the arms could still raise and lower fine but removing pretty much all of the gross wobble.
I am not recommending you do this (it's my quad, not yours and if you mess up you can over tighten the joint and possibly lock it up, burning out your raise/lower motor) but it is reversible, but it definitely helped. For the record, I used 3M VSB tape. It worked perfectly, as it is basically sticky rubber.
The key goal for me was to remove the harmonic shaking in the arms to isolate any remaining vibration to just the gimbal itself.
What better way than to test in insane winds? I could fly freely and aggressively with the prop locks finally installed, and see how the aircraft really holds in insane gusty winds.
I flew in very strong cold wind today at about 12 degreed F with gusts to over 25 MPH. The T joint was tightened and verified before hand.
In my test flight after the fix, there was shake whenever the crazy wind gusted, but not really that wavy jello. To clarify, I pointed the camera at the aircraft and looked. The arms were not shuddering or vibrating like before - they were rock solid. When you saw the wind gust in the trees, you could see gimbal move. It was GUSTY.. and the motors were constantly rapidly changing speed noticeably to keep the aircraft stable. At many points it was at maximum tilt in some direction, shifting rapidly as the wind did.
I was kind of shocked at how well the inspire handled this. The P2 could not have handled this wind safely (I have tried it) without some white knuckle moments wondering if it would even make it home. The inspire can handle it, even in GPS mode, never mind ATTI which you can get more power out of. I rapidly moved it all over the place and it was like it was on rails. I was incredibly impressed once I could finally open this sucker up with the prop locks on.
Back to the footage:
When I turned the camera to look at the aircraft, I could see no shake or vibration in the arms that I saw before. The shake was just the camera gimbal blowing around in the heavy wind. When the wind was still, so too was the image.
That I was able to get any usable footage in this insane wind was shocking. About 1/2 the flight was usable. And when I looked at the aircraft it was wildly adjusting all over the place due to the fierce changing winds, with the gimbal bouncing like a basketball, but the ground remained (mostly, relatively) steady. And the motors and arms were not shuddering or shivering like before.
I definitely need to do more testing tomorrow, in calmer winds, but so far so good. These tests are not yet conclusive for me, but I have hope at least that I can get footage in calmer winds just as good during the day as what I get in the evening, in overcast conditions, etc.
PS - I made a neoprene wrap with velcro that wraps around the battery for cold flights. The batteries have two little velcro strips on each side, and I cut the neoprene to wrap around the back and fit to each side. It's reusable, and the battery was warm at the end of the f-ing freezing cold flight. I will post photos at some point. I got 13 min of flight to 30%, and 15 min to 10%, which is what I get in warmer weather. Without the jacket, the battery drops like a rock quickly when it gets under 50%.