GoPro on Trex500 with floats for water takeoff/landing

[G. Bird]

I quickly attached some floats to a Trex500 and did some water takeoffs and landings at a rc boating club. This was our first session trying to film some rc boating action for national titled electric boat racer Bill Oxidean. Got paid $40 bucks too, haha! Got some useful clips but could have had a better flight plan. Our first time trying though just having some fun anyway..




1st person view:


3rd person views:

[G. Bird]

I was going to make a video just to test stability/vibration today but it looks like it turned into a video about a maritime disaster. I had landed on the water fine, but this time I tried spinning up the blades before they had come to a stop, causing it to tip over forward and capsize. The bubbling sound you hear underwater is the ESC burning up. There was smoke coming out from the water. You can see how dirty that water was, I had to swim through it to get my heli back. Below is the flight video from the recovered blackbox..

[R_Lefebvre]

Wow, what made it tip over like that? The pontoons do look a big short to me, and you had them mounted a bit far back. But what was actually the force the caused it to tip?

[SFACV]

G Bird, cool idea, sorry it went bad. Not even an opinion here as to what happened. I haven't been brave enough to try floats on a Heli yet. Have had to pull too many planks out of the water for various reasons and not going to risk the Heli.


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[R_Lefebvre]

Yeah, at the Autonomous Vehicle Competition this year, we had to fly 400 meters out over water. Nobody had any floatation. I was extremely nervous obviously.

The thing that got me was... even with those floats, if the impact was hard the floats will just rip off and you'll lose the whole machine. I was trying to come up with a well engineered boat hull that would bolt securely to the frame. Didn't get it done in time, so I didn't risk my 600 and just used the 450.

[G. Bird]

I should have just landed on the grass, I decided a water landing at last minute with the intent to take off again. What happened was I tried spinning up the blades again before they had slowed to a stop and that somehow kicked it over.

It is a little top heavy, I already knew from previous tests it could tip over forward. However I had adjusted the floats various times, you can see they are centered under the main shaft and CG..The floats came from a Kalt Baron .28 gasser which is actually a little bigger, but would have sat lower. If I had scooted the floats forward, the tail would have come too close to the water, creating a bigger hazard for capsizing. Yes the floats could potentially get ripped off in a water crash.. there are 8 tie wraps on it though, hope at least 1 keeps hold. they are more for piece of mind just to keep the heli from sinking to the bottom in a crash, not really intended for constant water takeoff/landings

After reading Rob's post on arducopter I finally decided to buy it last week. Would have put it on the Trex500 this week but looks like I need to dry it out / replace ESC first now.. Keep up the great work on arducopter Rob!!

[SFACV]

Just a thought, maybe your blades were not tightened exactly the same in the grips and one lagged back when you went to spool up, this would cause the whole heli to do some nasty maneuvering and with floats... you know. Bit of a shot in the dark but thought it may be a cause.

[R_Lefebvre]

Yeah, exactly... I bet what happened is that since the rotors were still turning slowly, the when the motor started, it was disengaged from the main shaft, so it accelerated hard, and then the one-way caught, which jerked the main blades which folded up and then wobbled it over.

[G. Bird]

Yes it was that exactly, which is ironic because I had made the video to show how loosening the blades so they can lead/lag easier had solved one of my vibration issues. Also, when I had landed I had kept it in idle up after turning on throttle hold. When I flipped it back to spin up again, it kicked in full throttle giving it a kick when I should have gently sped it up.

That said.. I got rid of the majority of side to side camera wobbling with looser blade grips, and mass/weight of the floats also helped. Regarding the other post on vibrations I had intended this video for, I agree that a hardpoint is almost all you need with some high frequency damping for helicopters. I never balance my blades or match their CG's, the most I do is ensure I use the same pair out of the box, for Edge blades they always seem to be within 0.5g.

[R_Lefebvre]

Half gram? I'm balancing to 0.01g!

Interesting, so you found that looser grips helped? I'll try that. I was going tighter trying to solve it.

[SFACV]

Originally Posted by R_Lefebvre

Half gram? I'm balancing to 0.01g!

Interesting, so you found that looser grips helped? I'll try that. I was going tighter trying to solve it.

So is it wrong that I have never put a blade on a scale?

And I have found similar results with blades running a bit on the loose side, especially at lower headspeeds. Only ones I heard of that wanted blades tight was the Goblins because they were having issues with boom strikes. They wanted blades tight so they didn't swing back and hit the boom on certain maneuvers.

What I usually resort to with blade tightening is to turn the heli on its side and loosen the blades so they just drop with their own weight, tighten them back up till they just hold straight out and if you give them a tap they will drop to almost straight down. Easy to get them both the same by this method and they tend to fly nice at that. Works for any size blade, larger blades need to be tighter but the weight of the larger blade determines that.

[R_Lefebvre]

Yeah, I'm WAY tighter than that. I'll try looser. The only problem with loose is I still get it cocking back in the grips on spoolup sometimes.

So is it wrong that I have never put a blade on a scale?

I was just trying to be funny. This is what I've been doing since it was recommended here by others. I don't have a dog in the fight either way.

[SFACV]

If the blades don't like initial spool up give them a little spin by hand before you hit the throttle. With Kontronic ESC's I find the soft start works well and the blades don't move. When I was using the Scorpion ESC I had to give them a little spin or they would swing back.


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[StatiC]

Can you show some closeups of your camera mounting scheme? I used to attach my camera to the big battery of my 6s Trex 600 and got pretty good results with that.

[G. Bird]

I probably could have mounted it to the battery tray in the beginning if I spent more time thinking it out, but I was in a hurry and wanted to use the waterproof case and gopro mount. Then the existing battery tray would have elevated it too high and make it susceptible to being struck by the flybar. So I used a spare battery tray and mounted it on the bottom, and put in some metal brackets to stiffen it up.

Based on various mounting schemes on trex500 and 700, so far it seems rigid hardmount produces the most stable video (assuming the heli is running smooth).
I posted pictures of the mounts in another thread, "GoPro sidemounted on Trex700" https://www.helifreak.com/showthread.php?t=554613

Currently working on a 3axis mount, coming soon.. Here's the trex500 mount: