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Old Feb 03, 2012, 12:25 PM
TREX 450 FPV Holy Grail
sia100's Avatar
Central Texas
Joined Apr 2009
437 Posts
Scott,

I'm a little less than half stick. I haven't tweaked any transmitter settings yet, so everything is really linear still. So that should equate to a little less than half throttle. It feels like it has plenty of power. This is with the 10 x 4.7 blades. I also have the 11 x 4.7 that David recommended for heavier payload. Not sure if I will need to move up to that config when I stick my gopro on.

Two gopros in a 3d config, eh? I like it! How will you be getting the two feeds back and converging them? What display/goggles will you use? I am interested in seeing how that turns out.

-Sia
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Old Feb 03, 2012, 01:10 PM
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United States, NJ, Stanhope
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Sia,

This is there 3D set-up, http://gopro.com/hd-hero-accessories...FeNV4god6nZZ4w I figure I can build a foam case to hold the two cameras it the correct position and drop most of the weight of the plastic housing.

They give you a cable with the set-up that syncs the shutters on the two, and then also some free software to converge the two images in the computer.

The rub is that you can't view it 3D live, given the proximity of the two cameras, I'm not even 100% sure if I can get a 90 degree cable into one to give me live out, may need to add a small security cam for the FPV and then just let the gopros record and go to 3D in editing. But... I think that it could be a pretty cool end result, when I look at how tight you can fly these multi-copters, I think a flight up and over trees, down along the river, etc. would be pretty cool.

-Scott
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Old Feb 03, 2012, 06:09 PM
TREX 450 FPV Holy Grail
sia100's Avatar
Central Texas
Joined Apr 2009
437 Posts
Very cool Scott. I may have to check that out. I guess you wear the type of 3D glasses you get at the movies? I will be impressed if you can build a 3D gopro coupler out of foam!
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Old Feb 03, 2012, 06:47 PM
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Sia, the two cameras just need to be parallel and about 1/4 inch apart, I figure I just need to measure the box from the actual case and then cut an opening. Shouldn't be too bad.

On the playback, you have a few options on how to save it, but yes the analagraph red/cyan glasses is what I have used so far.

-Scott
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Old Feb 03, 2012, 08:58 PM
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Quote:
Originally Posted by crezzee View Post
Finished mine recently, one thing i changed was the UC. In true RCExplorer style i used massive cable/zip ties

Another more important thing i've done is add a 'front' to it for LOS flying before i add the fpv gear. I've noticed that many multicopter pilots seem to identify the tail, usually by painting it a bright colour. Personally i don't think this is a good idea as it may encourage the pilot to look for the tail during loss of orientation (which is very easy with a symetrical craft like a tri or quad). I remember back to my rc heli learning days, an experienced heli pilot said:

"Always look at the nose of the heli instead of the tail"

This helped massively with orientation as yaw left moves the nose left and yaw right moves the nose right. Now i know this sounds obvious but if you're concentrating on the tail, yaw left moves the tail right..... and before you know it you've 'bought the farm'.
This will not be an issue when flying fpv......... hope my new vtx turns up soon.

A quick test vid, think i went a bit ott on gun n lasers:
http://www.youtube.com/watch?v=hyo9Sg8Q6zA
what are you using for the landing legs? plastic strips?
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Old Feb 03, 2012, 09:10 PM
TREX 450 FPV Holy Grail
sia100's Avatar
Central Texas
Joined Apr 2009
437 Posts
Phase 2: Dialing everything in

Once I got the tri airborne and hovered it a few times, I was forced to acknowledge that while it did fly, it didn't look very happy. I could see the frame and arms jiggling during hover, and the tail motor was waggling slightly...constantly. Vibrations everywhere. Consulting the forum archives returned: Prop and Motor Balancing!

I watched a few vids and read posts. Then I went to my LHS and bought the Top Flight magnetic prop balancer for $20. I balanced my props.



One thing I noticed as I was working with the props and motor shafts, was that the props did not seem to be srewing onto the shafts "true" or "plumb". These were the first props I'd ever screwed onto a shaft (I'm a heli guy :-). so I'm thinking i didn't realize how critical the initial screw on was. I did a lot of searching, but never really found anything about it, but at the end of the day my props were both out of balance, and they were not lined up exactly parallel to the shaft when screwed on. It seems prop adapters are way more popular than the screw shafts of these DT750s, and I can imagine they mount props much more precisely.

Edit: I learned later that I should have drilled out the prop holes to 4mm (5/32"), instead of screwing them on. Once I did that, the alignment problem I referred to above went away. Then I balanced them again since I'd removed a little plastic from the inside of the prop hole with the drilling. I left the washers on, though, because of the nice surface area they covered on the prop barrel. It just felt like it imparted more authority to the overall prop mount.

I used some 4mm washers between the nylon locking nuts and the props to try to force the prop into alignment with the shaft. There was some play in the props, so it actually ended up working well. Two props ended up lining up almost perfectly. The last one was off by a little, but definitely improved. I guess I'll be more careful the next time I screw props on a shaft for the first time! Here is the final result on the one that was a little off:



I hovered it again after the prop balancing and shaft alignment, and the difference was significant! No more tail servo waggling. No more visible vibrations in the arms. It hovered hands off longer, and control was more precise. I decided not to do the motor balancing until I could see a need to, but I'm pretty sure that will result in at least some improvement, too.

In working with the props, I noticed that the JB Weld I'd used to secure the motor wires had set too fast and didn't bind to the surfaces. Wires were moving a lot. So I bought some regular epoxy and addressed that. Much better now.

I also replaced my "test and build" receiver with a regular duty one. I'm using 72 mHz for all of my initial building, tuning, FPV testing, etc. Once everything is ready, I'll buy a second Dragonlink receiver and install it for the final config.

Also, I thought "I'm going to flash to 2.5...that much be so improved!". It seemed to have a negative impact, but I don't recall the exact differences. After reading more I came to the conclusion that I at my stage, I should only use the versions that the forums were frequently referencing. So back to the stock David configuration on that element: Tricopter version 1.6.

After I went back to 1.6, when I applied throttle, the props all started spinning up at different times. I guess I wiped out my ESC throttle range settings by flashing. I used the KK instructions to set throttle on the ESCs (which I'd had trouble with before...not sure what I did different this time, except read more carefully :-) Worked great, but then I discovered that my gyro had reversed!

So I decided to reset the KK settings back to default (again, per the KK manual here). Still reversed, so I followed the instructions to reverse gyro direction.

NOTE: There were inconsistencies between the beeps and blinks that the instructions said to expect, vs. what I saw. To sum it up, don't get all hung up on whether you get two blinks or three, and you should be good. Any series of blinks should indicate completion of any step you are on in the sequence. At least with this firmware version and Turnigy plush ESCs, you should never get continuous beeps.

During the course of this trial and error process, once when I was in a hover, my battery strap slid off the mount and the battery dropped, hanging ~6" under the tri. It was interesting to say the least, for my center of gravity to drop 7 inches during a hover in my living room. I took that as a sign that it was time to mount velcro in between the tray and the battery, in addition to the strap wrapped around them. Much better now.

I ordered a couple of 2450 mah 30C batteries to replace the 2200 20C I've been building and testing with.

At this point, the only thing I know of that needs work is the landing gear. I really like what crezzee did with his. Big black zipties:



Lol...here is what mine look like right now...all squished down. Not sure if my rig is that much heavier, or the zipties are too thin, or too short. Crezzee...any comments?



The things I want in my landing gear are:
  • simple
  • light
  • easily replaceable
  • low profile/understated
  • should flex easily when the tri lands

Suggestions??

Weather permitting, I'll do some limited orientation flying tomorrow morning. Unless I notice anything else that needs attention, that might mark the end of Phase 2. Tomorrow will be one week since I started the build. Thanks to the excellent help from all of the folks on RCGroups, KKMulticopter, RCExplorer, AllThingsCrash, and Waco Hobby Shop, I've been able to complete in one week what would have otherwise taken me months.

After phase 2, I'll start collecting and mounting the FPV components.
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Last edited by sia100; Feb 05, 2012 at 01:27 PM. Reason: Ongoing build
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Old Feb 04, 2012, 07:07 AM
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There are 3 different type of 1.6 firmware which one is everyone using?
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Old Feb 04, 2012, 08:09 AM
Do a Barrel Roll!
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United States, OH, Medina
Joined Jun 2005
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In regards to screwing you props onto the shafts........you should not have to do this.

You should buy a reamer, or drill bit, and drill out the props to proper size. They should slide right on the shaft. I've never heard (or had a model) that you physically had to screw a prop onto the motor shaft.

The proper order of hardware on the motorshaft should be
- locknut
-prop
-washer
-locknut

You can see this in rcexplorers pictures.

For landing gear, it seems people are using pool noodles for learning, then move onto the gear in rcexplorers 2.5 build

From what I've read, dont be too eager to throw fpv gear on it. I've read of lots of people with tons of multicopter flying under their belt struggle with fpv flying with these. Mainly because moving backwards creates the illusion of gaining altitude, and vise versa I believe.

donno if you've seen this
Flite Test - Tricopter Tips - FLITE TIP (9 min 27 sec)
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Old Feb 04, 2012, 09:31 AM
TREX 450 FPV Holy Grail
sia100's Avatar
Central Texas
Joined Apr 2009
437 Posts
Thanks rcbif. I appreciate your insight. Good info on the prop mount. I guess that is why I didn't find anything about screwing them on...because you don't! :-) But I didn't read anything about drilling them out, either. On David's 2.5 build page, he says "I also like the 4mm threaded shaft as you can mount the props straight to the bell without any extra weight or hassle." I took that to mean that you just screw them right on. Also in a picture from that post, I can't see any sort of anything on the prop shaft, other that the prop and the locking nut:



Do you think he drilled out the prop hole?

I guess if I can't come up with anything with more flex than the G10 gear David used I'll go with that approach.

Regarding the difficulties of transitioning to FPV flight, I would hope that fpv flight on a tri would be similar to doing FPV on a heli. Possibly even a little easier, since the multicopters are a bit more stable in general. Here is me doing FPV on my Trex 450 last weekend. Do you think my experience with FPV heli will transfer well to FPV tri?

Hei - 1400 ft flight at dam (5 min 3 sec)
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Old Feb 04, 2012, 09:33 AM
TREX 450 FPV Holy Grail
sia100's Avatar
Central Texas
Joined Apr 2009
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And by the way...no, I hadn't seen that particular video on Dave's tri. Thanks! It puts a lot of useful info together in one place. After watching it, I've decided I will definitely balance my motors individually, without props. I'm also going to dial in the expo and rate settings he recommended. Thanks for your contributions, rcbif!
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Old Feb 04, 2012, 11:00 AM
Do a Barrel Roll!
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United States, OH, Medina
Joined Jun 2005
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Here sia100, (quoted from 2.5 build)

"Landing gear mounted with zip-ties and prop mounted on the motor. The prop needs to be drilled to 4mm. I simply drilled it out with a power drill. Make sure to use lock nuts, otherwise the props will come loose over time. Also make sure not to over tighten the props. The bell can be pushed down to hard and create unnecessary friction against the bearings."

so it sounds like he just drills them out before mounting.

Also, I guess from davids wording it does not sound like he has a nut on the otherside of the prop though like I was saying. If you watch this video below, (from :45 on) that's how I would have thought he would mount a prop to keep pressure off the motor bell, and keep the prop from possibly spinning on the shaft
How to swap a prop on a Super Cub. (3 min 11 sec)


you can see in that video, the order goes, nut (or locknut), washer, prop, then the nut that fits into the hex indent on the back of the prop. It's a plane, but that should be irrelevant.

Granted, I dont have the motors for my tricopter here yet, but this has been the same with the past few planes I have owned.

Also I'm sure your heli experience will easily translate for the tri. I'm a fixed wing pilot going to these wirrlybirds, so it will be a learning experience for me.
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Old Feb 04, 2012, 01:34 PM
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Very nice build! I have a couple of questions for you, or David, (or anyone who has done this same build).

1. As far as the zip ties holding the motors, servo, etc. Do you ever have to worry about them wandering? Like the motors wanting to vibrate up or down the arm over time? I was always worried about that, and when I built a quad using the zip tie method, I put mounting tape under the motors before zip tying. However seeing how you and David don't, I'm starting to think maybe I'm wasting my time doing it.
2. Do you ever have to worry about the arms folding or moving while in flight? I've wanted to build a folding tricopter like this, but it always scared me that there doesn't seem to be any sort of retaining latch, or anything other than a small amount of friction holding them in place. Maybe I'm worried over nothing?
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Old Feb 04, 2012, 02:43 PM
TREX 450 FPV Holy Grail
sia100's Avatar
Central Texas
Joined Apr 2009
437 Posts
Quote:
There are 3 different type of 1.6 firmware which one is everyone using?
freshmint: There are three that I find, like you said. the default one, one called "acro", and one called "aggressive". I used the default one. I have not tried either of the other two, but based on their names, the default one will probably end up being the best choice for basic FPV flying.

Quote:
"Landing gear mounted with zip-ties and prop mounted on the motor. The prop needs to be drilled to 4mm. I simply drilled it out with a power drill. Make sure to use lock nuts, otherwise the props will come loose over time. Also make sure not to over tighten the props. The bell can be pushed down to hard and create unnecessary friction against the bearings."
rcbif: I stand corrected! I don't know how I missed that sentence. Pretty important, though. I'll add drilling out the props to my list of things to do. Thanks!

Quote:
1. As far as the zip ties holding the motors, servo, etc. Do you ever have to worry about them wandering? Like the motors wanting to vibrate up or down the arm over time? I was always worried about that, and when I built a quad using the zip tie method, I put mounting tape under the motors before zip tying. However seeing how you and David don't, I'm starting to think maybe I'm wasting my time doing it.
2. Do you ever have to worry about the arms folding or moving while in flight? I've wanted to build a folding tricopter like this, but it always scared me that there doesn't seem to be any sort of retaining latch, or anything other than a small amount of friction holding them in place. Maybe I'm worried over nothing?
Carl...good questions. I had the same concerns.

1) I wondered if the motors would be secure enough, too. But the zip ties do a great job of keeping the mounts and servo pressed firmly into the wood arms. You might be able to manually budge the mounts, but it would not be easy. And unless you have a lot of vibes, I don't think they will ever move on their own.

2) The arms folding was also a concern of mine. The screw that is farthest out on each arm of the frame acts as the compression adjustment. I just screwed it down tight enough that the leading edge of the arm slides into place will little force, but as you continue moving it into its extended position, it gets tighter and tighter, requiring a two-handed torquing into final position, where it is butted up against the compression screw. I used locktite on all the screws, so they won't move, either. After a good bit of folding and unfolding, I am sure the wood will compress a little, and may require the compression screw to be reset slightly more tightly, but so far I have not gotten to that point.
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Old Feb 04, 2012, 05:57 PM
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The folding arms are also designed that way to help make it portable, but also so that it folds in a crash instead of breaking. As long as they are tight and not flopping around you should be fine.

Also sai, did you say you used locktite on the locknuts as well? No need to use it on a nylock, the cutting of the threads into the nylon is the lock device.

-Scott
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Old Feb 04, 2012, 07:11 PM
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Sia, your progress is awesome!!

I am sorry that I missed getting your email in a timely manner - I would have loved to see the Tri fly in person. I spent all day in SkyWarn training today so I can be an "official Storm-Spotter" (I just got home! LoL). I was over at the MCC Emergency Services Education building all day, so naturally, when I drove by the dam on my way home I looked to see if you were there.

Keep up the great work and I'll try to get out there with you and Doc sometime soon!



Thanks for the nice shout-out in your first post. I'm always here if you need anything else cut.
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