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Must. Use. Threadlock.

colorex

Rotor Riot!
Mentor
#1
Ok, so today I flew my Tricopter in a public school that's close to my house. I had to display the tricopter's flight mechanism to some kids, so I did my favorite maneuver - powerlifts. Yup, I made the name up, just nail your throttle up, take the tricopter up 50 feet, and then take it slowly back down. The best part with the powerlifts is probably the initial surprise factor. You fly your tricopter to make it look like it can barely fly, then BOOM a powerlift, or a powerkick - made that up too, same thing but forward. So I did bout 5 minutes of flying, was doing my 6th powerlift when something happens - the Left motor pulls out of it's mount. I was at about 15 feet high up, when the motor jumped out, hit the prop to the arm, and the tricopter immediately lost control. I chopped the throttle, which has a significant impact on how you crash, but it was already to late as the tricopter was tipping over. If you chop the throttle immediately, your tricopter might not flip over - if it does flip over, it will kill the board and destroy the motors.

My crash was extremely unlucky. Cause the aluminum tube on the tricopter hit the motor perfectly where the windings go out - chopping a bunch of wires after crushing through the epoxy. So now I have to get some money, buy a spare DT750, hope that they are in stock, and wait till it gets here. Time to fly my Bixler again.

Other damage included a smashed prop, dented aluminum tube, dented battery, and broken yaw mech. The latter is certainly no reason to cry, as the break-away mechanism I made with hotglue worked perfectly and the servo is still intact.

Damaged winding:



Damaged motor cables:



Dent in the aluminum from the crash:



Smashed prop:



Yaw mech unglued:



Puffed LiPo:



The reason for it all:



Cheap me didn't want to spend on threadlock - cost me a motor.
 

bmsweb

Site Moderator
#2
Bugger, I think that's the thing with TriCopters, Quads etc. They work so much harder that you really need to keep an eye on things all the time. A preflight check is really the way to go. Mind you in this instance ThreadLock would have been even better. When my mate JB lost his Tri in the lake it turned out it was due to the prop cracking. Its something we don't think of but it can happen and unfortunately a cracked prop that comes off in flight is a lot worse for a multirotor than it is for say a plane like the bixler.

In any case after he recovered the Tricopter it turns out it has stress cracks in the same area on the other two props! The up side is we learn from these accidents. After the loss of a plane 15 years or so ago, I will do preflight check of my models before every launch.

Thanks for sharing your experience . . sorry about the crash too!
 

colorex

Rotor Riot!
Mentor
#3
The bummer is that I only got two batteries of flight with it since last crash when I wrecked the yaw mech. But the upside is that now I have a motivation to rebuild my tricopter, using the new prototype I'm working on.
 

bmsweb

Site Moderator
#4
The bummer is that I only got two batteries of flight with it since last crash when I wrecked the yaw mech. But the upside is that now I have a motivation to rebuild my tricopter, using the new prototype I'm working on.
That is the upside no two ways about it. I tell my son it perfectly fine to make a mistake but the only time it becomes a problem is if you don't learn from it. From what I can tell you're quick to learn and share your experiences and that's what its all about. My camera mount for my Bixler is at Revision 10 or more lol . . interested to see your new prototype :)

Speaking of Threadlock I will buy some today :) Thanks for the reminder
 

Ak Flyer

Fly the wings off
Mentor
#5
Sorry to hear that. The biggest down side to multi rotors is once they lose power they can't glide or autorotate. Did it damage your board?

I know a guy who was flying FPV with his tri when a prop came off.

Here's the video
 

colorex

Rotor Riot!
Mentor
#8
That is the upside no two ways about it. I tell my son it perfectly fine to make a mistake but the only time it becomes a problem is if you don't learn from it. From what I can tell you're quick to learn and share your experiences and that's what its all about. My camera mount for my Bixler is at Revision 10 or more lol . . interested to see your new prototype :)

Speaking of Threadlock I will buy some today :) Thanks for the reminder
I will now use threadlock, or at least some hotglue over the screw. I just built a Bixler camera mount, but I need to go through a couple more as I cut along the lines, and my misshapen Bixler was a bit wider over the top.

My new prototype is based on battery protection (dinged/bent my two batteries in crashes), portability, contained electronics, and crash safety. I'm trying to contact Eric so I can use his yaw mech, it looks super sturdy.

Sorry to hear that. The biggest down side to multi rotors is once they lose power they can't glide or autorotate. Did it damage your board?

I know a guy who was flying FPV with his tri when a prop came off.
My board is safe. I might even flash it with Aeroplane firmware now that the tricopter is disabled for about a month! Try it out in the Bixler...

The damage on the tricopter is usually very dependent on how you crash. If you lose power (ESC LVC cutoff) from low altitude in a hover (which is my case, usually) then chances are it won't flip over. damage comes when it flips over and hits the side or the top. I use EPS foam for landing gear, and they absorb impact awesomely. They do bounce, but all the other gear do to. In my crash the aluminum tube lined up with the motor wires, so the square hole of the tube hit the motor right where the cables join the windings, cutting off a lot of copper wires to the stator. The hit pulverized the epoxy I had put there.

Bad news Colorex. Let me know If I can send you some parts to get going again

//UndCon
OK, Thanks! PM sent.
 

Ak Flyer

Fly the wings off
Mentor
#9
I learned pretty quickly with nitro planes and helis that thread lock is your friend. It's also good to have a couple grades and know where they are used. Things you don't ever want to remove again get red. Things you disassemble or adjust occasionally use blue.
 

colorex

Rotor Riot!
Mentor
#10
I learned pretty quickly with nitro planes and helis that thread lock is your friend. It's also good to have a couple grades and know where they are used. Things you don't ever want to remove again get red. Things you disassemble or adjust occasionally use blue.
I have red threadlock, and I call it superglue. On the pushrod thingies on the tail of my Bixler I used superglue, and when I tried to unscrew it, the head of the screw came off first.
 

jetpackninja

More combat please...
Mentor
#11
Red is permanent. You have to use heat to get it out.
Blue is less permanent but I've also had to use heat form time to time to get a screw out.
I only use blue...
 

colorex

Rotor Riot!
Mentor
#12
Red is permanent. You have to use heat to get it out.
Blue is less permanent but I've also had to use heat form time to time to get a screw out.
I only use blue...
CA (plain superglue, I get a really good generic one for $0.25) is permanent heat-resistant threadlock.
 

Ak Flyer

Fly the wings off
Mentor
#13
CA (plain superglue, I get a really good generic one for $0.25) is permanent heat-resistant threadlock.
What CA isn't though is vibration resistant. It will crack and lose strength in metal to metal joints. I highly recommend buying real loctite from either loctite brand or permatex and you will not regret it. I have used CA in a pinch but always remember to clean it out and use real loctite afterwards. I will use CA to form threads in wood when putting screws in and it works very well, much better than loctite but for metal to metal I make sure to use the real thing.
 

jetpackninja

More combat please...
Mentor
#14
+1 mate!
Locktite is purpose designed.
Sure, CA in a pinch, but don't cheap out.
Don't trust brittle CA for this application.
You learned your lesson once ;)
 

colorex

Rotor Riot!
Mentor
#15
Yeah, I don't want my stews glued in forever anyway. I think I know a place where I can source TL. About $8 for that tiny bottle.
 

Tritium

Amateur Extra Class K5TWM
#18

lobstermash

Propaganda machine
Mentor
#20
Hahaha. @ Tritium, they're a good idea for sticking in your tx with the lithium battery in there, because you don't ever think to charge them (you forget because it only happens every couple of months)...

I remember when I got my 9x. It drove my wife crazy when I was playing with it (trying to figure the damned thing out). To tell you the truth it drove me crazy too.