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Old Jan 30, 2012, 01:23 PM
TREX 450 FPV Holy Grail
sia100's Avatar
Central Texas
Joined Apr 2009
437 Posts
Build Log
RCExplorer Tricopter v2.5 FPV platform build

This is a build log of my RCExplorer-based FPV tricopter. Each phase is documented in a single post, with plenty of build pics, and there are related comments and dialog from other contributors throughout.
  1. Frame and Electronics Initial Build (This Post)
  2. Optimizing Powertrain and Electronics for Stable Flight ( Post 21)
  3. Test-Mounting FPV Components ( Post 69)
  4. Fine-Tuning FPV Build
  5. Dragonlink Receiver Installation and Final Adjustments


Phase 1


Recently I decided to do a build of David's (rcexplorer.com) version 2.5 tri. The simplicity and crash survivability of the design appealed to me, Plus I like its clean lines.

Here is the link to David's build log which I used extensively. http://rcexplorer.se/projects/tricop...copterv25.html. Note that there are important design and assembly elements tucked away in all of the version build logs he has there (1/1.5, 2, 2.5) and I recommend reading them all several times if you want to end up with an excellent build.

As to survivability, parts are designed to pop off or pivot when there is a crash, instead of breaking or bending electronic or power components. Worst case, one of the arms will break, which is a $1 part and easy to replace. And based on my Trex 450 track record, I will be crashing. So I decided it would be to my advantage to figure the crashes into the build :-)

I wanted to mirror Dave's parts list as precisely as possible, to minimize surprises...at least for this first tri build.

I bought most of the parts from Hobbyking, using David's shopping list (very helpful!), except where they were out of stock, as was the case for the 18 amp Turnigy plush ESCs, and the tail servo. I was able to find 25 amp Turnigys elsewhere (couldn't find any 18 amp Turnigys, so I scaled up). The tail servo I ended up using was a Turnigy TGY-930 from HK. I also used the HK KK controller board. And I picked up the CF rod at Hobbytown.

Here are all of the parts, or at least most of them, ready to experience life as a tri:



For the center frame, my friend (and all around great guy) Mike "crash" Hancock cut the G10 from plates I ordered from mcmaster-carr.com (9910T15 Multipurpose Garolite (G-10), 1/16" Thick, 12" X 12"). Mike's site has some really excellent video blogs and other resources on all kinds of RC stuff, including FPV and multicopters. He also scratch built the computer controlled cutting machine that cut my frame. Check out his site at http://allthingscrash.com/.

Here are the plates he cut from the G10 sheets, and the battery tray/gopro mounts from 1/8" basswood plywood. Note that there are two complete sets in this picture:



I started with the main frame components:



I made sure that the top and bottom G10 plates' holes and edges were perfectly aligned before I did anything else:



Then I cut the arms (I used 48 cm, like David), and rough assembled them with the frame pieces:







Time to put together the tail assembly, which was part of the process I really enjoyed. Drill out one of the two interlocking landing gear pieces, line up its hole with the other one, and jam the CF rod through both:



Sand down the ridge on the back of the servo arm (I ended up using a different arm, by the way):



Center and CA the horn to the assembly so that a couple of the screw holes line up with solid plastic for drilling holes, and let CA set:



Drill holes, screw horn to assembly and cut off any unneeded parts of the horn:



Zip tie the motor mount on, paying very close attention to the orientation and direction of each zip tie:



I had to diverge from David's build here because of the different servo dimensions. I added a piece of wood as a shim under the assembly so that the servo would line up with the horn hole on the assembly when both pieces were sitting on the tail arm. Here I have a couple of screws I'm about to tighten to clamp the two pieces together and let the CA between them set:



And here is a picture of all motor mounts affixed to the arms:



Here is the basic frame and motor mounts assembled and extended:



On to the motors...I epoxied (actually JB Welded...I hope the iron in the compound won't mess with the winds of the motor!) the wires, per Dave's suggestion, to minimize metal fatigue:



Cutting down the motor shafts. I cut mine to 22 cm:



I also had to relocate the servo wires exit point to another side, since they were coming out of the side that needs to be flush to the arm:


Here is the finished tail motor and servo mount:



And here are all three motors mounted:



Now it's time to work on the electronics. I decided to flash the HK KK board next. Staying as true to David's build as I could I used firmware v1.6 (even though later versions were available.) I couldn't get the Sparkfun.com Pocket AVR programmer to work with my mac (which they pointed out on the product page might be an issue), so I worked from Windows 7. I ran into problems and had to do the following to get everything to work:
  1. Set the power switch on the Pocket AVR to "on"
  2. Reboot Windows 7 with the F8 boot option key pressed, and disable the device driver signing requirement (resets automatically to default at next reboot).
  3. Use the .33 version of KKMulticopter software to get around the "hang on flash" problem (instead of the current .53 version).

Here is a shot of the KKMulticopter software. I have the correct programmer type and KK board selected, and the default Y6 firmware is showing...hadn't selected the tri 1.6 version yet:



This is the Sparkfun Pocket AVR:



I ended up spending 2-3 hours on the flashing process before everything worked.

Time to finish the ESC motor and battery wire replacements:



Strapped everything together:



Back to frame stuff...building the battery/camera tray and vibration isolation coupler (I love the silicone tube idea):



[IMG][/IMG]

Strap in the ESCs and motor wires:



Connect the battery tray:



Hook everything up:



Glamor shot :-)



I took a page out of the Food Network programs and used a bowl to collect all of the bits and pieces of trash as I worked:



And then I hovered it the living room! It just worked. Awesome. Here is a post-hover pic:



So that is all for chapter one: Build the tri and make it fly! I started Saturday afternoon, and worked most of the the weekend and Monday night to get it from parts to a flying machine. I figure around 25 hours of work to get it to this point.

Up next: Tune it up, replace test receiver with a real one, and fix my initial build mistakes.
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Last edited by sia100; Mar 15, 2012 at 05:50 PM. Reason: Ongoing build...
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Old Jan 30, 2012, 02:46 PM
Do a Barrel Roll!
rcbif's Avatar
United States, OH, Medina
Joined Jun 2005
1,021 Posts
I'm working on mine too. Atleast as much as I can while my parts come from hobbyking. They really take time with their newyear over there, lol. Over a week and my order status hasn't changed.

How much did the shipping cost on the G10? I have a wood frame now, but want a lighter one once I'm done crashi---I mean learning.
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Old Jan 30, 2012, 03:36 PM
When in doubt, throttle out...
badlands's Avatar
Joined Mar 2010
1,552 Posts
I had to cut my G10 sheet by hand but apart from that this build is identical.

Last week i did this with it ->
Mansion - Tricopter flight (3 min 46 sec)
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Old Jan 30, 2012, 04:20 PM
Build Fly Crash Repeat
crezzee's Avatar
Worcester UK
Joined Nov 2004
760 Posts
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:
Tri Hard the movie trailer (1 min 38 sec)
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Old Jan 30, 2012, 06:08 PM
TREX 450 FPV Holy Grail
sia100's Avatar
Central Texas
Joined Apr 2009
437 Posts
Quote:
I'm working on mine too. Atleast as much as I can while my parts come from hobbyking. They really take time with their newyear over there, lol. Over a week and my order status hasn't changed.

How much did the shipping cost on the G10? I have a wood frame now, but want a lighter one once I'm done crashi---I mean learning.
Line Description Ordered Shipped Balance Unit Price Total
1 9910T15 Multipurpose Garolite (G-10), 1/16" Thick, 12" X 12" 4
Each
4 0 9.47
Each
37.88

Merchandise 37.88
Shipping 6.39
Total $44.27

So...$10 per 12x12 sheet, $6 to ship all four.

Would love to see a pic of your build, rcbif!

Quote:
I had to cut my G10 sheet by hand but apart from that this build is identical.
Badlands: Wow...handcutting G10. That is impressive. Super nice vid. I have the dragon link, too. That will be going on this tri. Plus a gopro I'll pick up at some point.

Quote:
Finished mine recently, one thing i changed was the UC.
Crezzee: What is UC? I love how clean your build looks in the pic. I've been planning on doing a similar approach as you with the landing gear, but can't think of what I can use to cut the circles from. What did you use?
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Old Jan 30, 2012, 06:51 PM
TREX 450 FPV Holy Grail
sia100's Avatar
Central Texas
Joined Apr 2009
437 Posts
Oh I think I see in the pic that you are using big zip ties. Cool. Does that work well?
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Old Jan 30, 2012, 07:18 PM
Registered User
Joined Dec 2006
212 Posts
Hi sia100
Where do you buy the wooden arms for Tricopter? Is it pine wood? It looks nice.
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Old Jan 30, 2012, 07:44 PM
TREX 450 FPV Holy Grail
sia100's Avatar
Central Texas
Joined Apr 2009
437 Posts
Quote:
Where do you buy the wooden arms for Tricopter? Is it pine wood? It looks nice.
Hi tuongnhu. I got these at a Hobby Lobby store. They are basswood. 3/8" x 3/8" x 24". $1.49 each. I've heard that on long pieces, pine will often warp and bend. Apparently bass wood stays straighter. Whatever you use for your arms, use something that will stay true.
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Old Jan 30, 2012, 09:33 PM
Fremont, CA
United States, CA, Fremont
Joined Jan 2009
1,600 Posts
Very nice build! Thanks for sharing.
Please check David's link - it's not working for me.
Thanks
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Old Jan 30, 2012, 09:43 PM
TREX 450 FPV Holy Grail
sia100's Avatar
Central Texas
Joined Apr 2009
437 Posts
Thanks djacob7.

I checked David's link. It works for me. Linking to it again here in case something is up with that post...http://rcexplorer.se/projects/tricop...copterv25.html

If it still doesn't work, google rcexplorer.com and see if you can get there that way. His site is chock full of good stuff.
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Old Jan 31, 2012, 04:24 AM
Build Fly Crash Repeat
crezzee's Avatar
Worcester UK
Joined Nov 2004
760 Posts
Quote:
Originally Posted by sia100 View Post
Crezzee: What is UC? I love how clean your build looks in the pic. I've been planning on doing a similar approach as you with the landing gear, but can't think of what I can use to cut the circles from. What did you use?
UC is Under Carriage and yes i use very big zip ties. So far they have worked great as they absorb some of my heavy landings.
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Old Jan 31, 2012, 07:39 AM
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AleG's Avatar
Bangkok
Joined Oct 2007
1,631 Posts
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
Boy, are you right...

I learned to fly my tricopter by looking a the tail, first time I flew it FPV I nearly crashed when the rudder was "inverted". After landing and giving it another go flying visually I went like: "What's the matter with this thing? left stick, tail goes left, good; right stick, tail goes right, goo... waaaaaaait a second..." Facepalm
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Old Jan 31, 2012, 08:51 AM
TREX 450 FPV Holy Grail
sia100's Avatar
Central Texas
Joined Apr 2009
437 Posts
AleG...were you able to reprogram your brain once you reversed back the yaw direction? That must have been a bit of a task!
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Old Feb 02, 2012, 10:25 PM
TREX 450 FPV Holy Grail
sia100's Avatar
Central Texas
Joined Apr 2009
437 Posts
Build Update...

I've been working on the build, but remiss in updating the thread. So I just updated the initial post to complete my steps to get a flyable tri in the air.

Here is a video of a back yard hover that marks the end of the first phase:

Rcexplorer tricopter v2.5 Hover after initial build (0 min 43 sec)
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Last edited by sia100; Feb 03, 2012 at 10:19 PM.
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Old Feb 03, 2012, 08:59 AM
RC Geek
Scott_NJ's Avatar
United States, NJ, Stanhope
Joined Dec 2004
813 Posts
sia,

Awesome post and thread, thanks for the update and great to see it flying. What type of power are you at to get to a hover? I know David flys his FPV so I am assuming it can hoist a bit of weight, I've got two go pros and have been toying with the idea of how much fun this thing would be carrying two of them in the 3D set-up...

-Scott
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