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Old Feb 07, 2012, 06:14 PM
TREX 450 FPV Holy Grail
sia100's Avatar
Central Texas
Joined Apr 2009
437 Posts
Scott: No worries ;-) Yeah, I'm liking the look and quality of the FPVManual version! No way mine will ever look that cool. But it will be more of a labor of love, for sure.

NiceGuy: Yes, I found the same to be true. Another reason why I went with David's model: he had a great build log and parts reference, plus he was three versions deep, and a great documenter. I suppose in a year or so the FPV multicopter "sets" parts lists and builds will start catching up with the FPV plane community.
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Old Feb 07, 2012, 07:15 PM
TREX 450 FPV Holy Grail
sia100's Avatar
Central Texas
Joined Apr 2009
437 Posts
Open question re: VTX antenna placement

So, I hooked up all of the FPV components, including the OSD Pro stuff. Short version is, it all works. But....

When I emulated David's VTX antenna placement, my rear servo was glitching all over the place. As I moved it away from the servo cable approaching 5 or 6 inches, things went quiet. I don't understand how he was able to get away with this mounting position for it:



I think I'm going to have to get a 6" or so length of stiff plastic something to elevate the antenna far enough from the servo wires to keep things quiet.

Anyone have any thoughts on why our experiences would be so different? I guess he might be using 1.2 or 2.4 vid freq. Either that, or he is magic (which I have long suspected :-).

-Sia
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Old Feb 07, 2012, 08:18 PM
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What do you think of this?
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Old Feb 07, 2012, 08:20 PM
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What do you think that extra cables for?
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Old Feb 07, 2012, 09:06 PM
TREX 450 FPV Holy Grail
sia100's Avatar
Central Texas
Joined Apr 2009
437 Posts
Quote:
Originally Posted by freshmint View Post
What do you think of this?
I think that looks bad-ass. That's what I think. Did you fabricate that?
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Old Feb 07, 2012, 09:08 PM
TREX 450 FPV Holy Grail
sia100's Avatar
Central Texas
Joined Apr 2009
437 Posts
Quote:
Originally Posted by freshmint View Post


What do you think that extra cables for?
The small extra power cable? That is to power the video transmitter.
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Old Feb 07, 2012, 09:16 PM
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Quote:
Originally Posted by sia100 View Post
I think that looks bad-ass. That's what I think. Did you fabricate that?
Yes I made it , are you going to use cover on your? Or going convertible
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Old Feb 07, 2012, 10:20 PM
TREX 450 FPV Holy Grail
sia100's Avatar
Central Texas
Joined Apr 2009
437 Posts
Quote:
Originally Posted by freshmint View Post
Yes I made it , are you going to use cover on your? Or going convertible
Wow, fresh...that is nice work. I'm going convertible for now. I'll be modding this thing for a while, though. I want to keep the weight as low as possible, without sacrificing the things I want. But I might play with some sort of cover at some point.
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Old Feb 07, 2012, 11:26 PM
TREX 450 FPV Holy Grail
sia100's Avatar
Central Texas
Joined Apr 2009
437 Posts
Phase 3: Test-Mounting FPV Components

Things are going well. Time to cannibalize my Trex for FPV components:
  • EagleTree OSD Pro
  • EagleTree DataLogger
  • EagleTree GPS Receiver V4
  • DPCAV 900 mHz Video Transmitter
  • DPCAV Vee Antenna
  • DPCAV microphone

I decided to follow in the footsteps of the greats and use food storage containers in my build I am going to mount the OSD Pro components and collect extra wire in a little food container that came in a set I bought at Ikea a couple of years ago. Here it is connected to the frame and with the OSD Pro and Data Logger attached:



I cut out most of the plastic on each end to allow for cable pass-through. It's working pretty well. I mounted the DPCAV mic inside the container and ziptied all of the extra wire in there, too:



When I did my first video transmission test, I learned that I wasn't going to get away with the same tight VTX antenna mounting position that David did. I thin he was using a different frequency that didn't cause interference with the tail servo wires. I'm using 900 mHz, and the proximity of the antenna to the servo wires caused unacceptable glitching on the servo. So I hacked a length of plastic from an old kitchen utensil tray, mounted it to the rear arm, and mounted the antenna to it:



I hooked up everything to do a test hover with FPV, and as I hit record, the gopro ran out of juice. So I hooked it up to USB for a charge and shifted gears. There is no hole in the gopro case for the live AV out plug. I had to make my own. This was painful. It felt like drilling a hole through my iphone. But there was no way around it, I had to drill a hole into the gopro case that I could plug the AV out in though. Getting ready for the operation:



Post-op:



I paused the gopro recharge long enough to weigh everything (minus lipo):



Here is how everything is looking at this point:



Gopro back on the charger, and on to the problem of landing gear. I'd tried several approaches, including foam, zipties, blades from an old CX2 Heli, and food container plastic. Non worked well (although I did not try crezzee's industrial strength ziptie solution, which looks to have merit). I ended up hacking up a busted Trex 450 CF boom into three equal length sections and ziptie-ing them to the arms:



Finally, the tri is ready for its FPV-loaded hover test:



Closer...



Time to take it up and watch the amps and other telemetry to see what this build has yielded. It's nighttime, and I'm recording through a stock whip antenna on a receiver connected to an igrabber, recording on my macbook air in the house. The tri is in the back yard, so there are plenty of transmission artifacts in the recording. I figure this footage might be helpful as a reference for others doing their first tri hover fully loaded with FPV gear:

Tri FPV First Hover (1 min 49 sec)


Results? Things are working! I think I'm on threshold of moving up to the next size props (currently at 10x4.7, next up: 11x4.7). But everything is working and looking good. Id say we have achieved basic FPV operations. Time to do a few test flights and play with the variables.

Folded up and ready for transport:

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Old Feb 08, 2012, 06:28 AM
Build Fly Crash Repeat
crezzee's Avatar
Worcester UK
Joined Nov 2004
790 Posts
looks great Sia, it will be interesting to see how long your flight times are with all that extra weight on board.

Couple of things:

1. What are your plans for the rx antena, will you just let it dangle down (it may get caught in the props)?

2. I noticed you have a mic for the sound, can you use the 'mic out' in the gopro instead?....this is what i'm hoping to do.

3. your cg must be a bit nose heavy with the gopro and flight battery up front, have you checked it?

4: Not sure about this one, but how about removing the gopro battery and powering it off a ubec to save some weight?

As you can probably tell i have a bit of a weight problem i really like to build stuff as light as possible as they fly longer, fly better and don't crash so hard.
My tri will be the diet coke of tricopters i,m not bothering with a full osd / data logger, just a simple osd with battery voltage monitor as i aim to fly this craft fairly close. I might even ditch the heavy gopro case like Badlands did. My goal is an all up weight of 1kg or less including fpv gear. At the moment mine weighs just over 800g including flight battery.
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Old Feb 08, 2012, 08:39 AM
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United States, NJ, Stanhope
Joined Dec 2004
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Sia, awesome progress, I am in awe. Looks great, ouch on hacking up the go-pro case, I was going to say, GoPro sells a 'skelton' case with the side open, but they also sell normal replacement ones as well. www.eyeofmine.com is a great site for some cool go-pro accessories as well.

On the OSD, I know you had the GPS on the T-Rex, do you think you need it on the Tri? I was wondering about range with the flight time of a tri, etc. Watching your AMPs, I was wondering if there is an OSD out there that allows you to monitor amps by motor, would be interesting to see what each of them was drawing at any one time.

Crezzee, don't quote me, but I don't think the gopro's video out supports audio out as well. On ditching the case, Tim from FPVmanuals has come up with a cool product that lets you use the lens protector from the original case and ditch the rest.

http://www.rcgroups.com/forums/showthread.php?t=1581997

-Scott
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Old Feb 08, 2012, 08:50 AM
TREX 450 FPV Holy Grail
sia100's Avatar
Central Texas
Joined Apr 2009
437 Posts
Thanks crezzee. Yes, now comes the slicing and dicing and fine tuning.

Quote:
1. What are your plans for the rx antena, will you just let it dangle down (it may get caught in the props)?
This is just the 72 mHz receiver I'm using while I wait for my second Dragonlink receiver (first one is in the Trex). The antenna on that is much shorter and shouldn't be an issue.

Quote:
2. I noticed you have a mic for the sound, can you use the 'mic out' in the gopro instead?....this is what i'm hoping to do.
I'm definitely going to check out the audio out on the gopro. I just haven't taken the time to make the final AV cable. I just did a quick hack job to get vid out and see if everything would work as it was on the Trex. Little by little I'll start adapting the FPV config to the specifics of the Tri. One thing I noticed in the first gopro recorded hover (front yard video earlier in the thread) was that the sound from the gopro was kind of rough, I think because of how tightly the gopro is coupled to the frame, and the vibes in the frame go directly to the gopro and then to the mic...hard to explain. Might be improved when I put the non-waterproof door on, which is supposed to improve mic audio. We shall see!

Quote:
3. your cg must be a bit nose heavy with the gopro and flight battery up front, have you checked it?
This tri is absolutely nose heavy. As will any RCE tri that has a gopro mounted way up there on the nose. As to its effect on flight? I couldn't tell one bit of difference. I have to think it is because the stabilization board just tells the front two motors to spin all the more faster to counter the extra weight. I think if a person was planning to do acrobatic flight with this model (poor coice in the first place!), they might feel the effects of the nose-heavy weight distribution. But I never felt anything last night during the test hovers.

Quote:
4: Not sure about this one, but how about removing the gopro battery and powering it off a ubec to save some weight?
Yes...I'm definitely going to test that. I've been reading up on it in the last few days, and it seems like people are doing it successfully. I'm just taking baby steps :-)

Quote:
As you can probably tell i have a bit of a weight problem i really like to build stuff as light as possible as they fly longer, fly better and don't crash so hard.
My tri will be the diet coke of tricopters i,m not bothering with a full osd / data logger, just a simple osd with battery voltage monitor as i aim to fly this craft fairly close. I might even ditch the heavy gopro case like Badlands did. My goal is an all up weight of 1kg or less including fpv gear. At the moment mine weighs just over 800g including flight battery.
Lol...yes, I like to shave weight where I can, too. Remember, this is just phase 3 of my 5 phase build: "Test-Mounting FPV Components ". Once I get everything working and test different configs, I'll lock it all down in phase 4. Phase 5 is replacing the 72 mHz with the DL, removing any extra weight I've found, and maybe making it look a little sexier. I definitely want to go through several "mini builds" because I've learned that they get better everytime I do one.

That is a great weight you have. I don't really need the data logging part. I just want amps, volts, watts, GPS altitude, speed, distance and direction and RSSI. I already had the OSD Pro, so I figured I'd start with that, and replace it with something lighter once I was flying, so I could base my OSD requirements off of real flight instead of what I think I will want.

Direct-mounting the gopro without the case, using some foam is also something I've considered. That is not completely out of the question at this point. I probably have aobut 2 weeks worth of different combinations of things I'd like to try before I have all the information I need to decide on my final FPV config. This should be fun!

Thanks for all of your questions and information, crezzee! It puts a lot of considerations all in one place.

-Sia
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Last edited by sia100; Feb 08, 2012 at 08:55 AM.
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Old Feb 08, 2012, 08:59 AM
TREX 450 FPV Holy Grail
sia100's Avatar
Central Texas
Joined Apr 2009
437 Posts
Thanks for the links, Scott! I will check them out.

I'm not sure about individual motor monitoring, but if it doesn't exist, I'm sure it will soon! I read stuff about th gopro live audio out not working, but I also read stuff that implied that it would work. So I'll just have to check out the leads to see if there is any signal there or not.
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Old Feb 08, 2012, 09:10 AM
Expat
Japan
Joined Apr 2010
3,026 Posts
GREAT documentation Sia, we need more posts like this. Time layer lens has good reviews. Definately cover the lens at least, othewise you're screwed. Your drilled case has the advantage of still being waterproof if you used a gromet/sealant. I'm pretty sure audio live out works with the right av cable. Audio is always terribleon my aircraft. In fact, I had video range decreased during audio noise. I think a volume limit and muffle on the mic is usualy required to be useful.
iPhone post, sorry for being curt.
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Old Feb 08, 2012, 11:39 AM
Build Fly Crash Repeat
crezzee's Avatar
Worcester UK
Joined Nov 2004
790 Posts
Quote:
Originally Posted by sia100 View Post
This tri is absolutely nose heavy. As will any RCE tri that has a gopro mounted way up there on the nose. As to its effect on flight? I couldn't tell one bit of difference. I have to think it is because the stabilization board just tells the front two motors to spin all the more faster to counter the extra weight. I think if a person was planning to do acrobatic flight with this model (poor coice in the first place!), they might feel the effects of the nose-heavy weight distribution. But I never felt anything last night during the test hovers.
David from RCE puts his flight battery way back to maintain balance with a gopro, check one of his vids.

Having a nose heavy tri may be ok in the hover but it will effect the elevator trim when in forward flight, at least mine did when it was tail heavy. Since i have got my cg spot on it does fly even smoother in fast forward flight and transitions into hover better.
Ideally you need to put your flight pack where your food box is to help the balance but i can see this maybe an issue in your setup.
Perhaps you could play with the CG in phase 6 or 7

Also a word of warning do not hit full power from rest to see how quick it will lift off the floor with incorrect CG. I almost lost my face when i tried this, the tri shot up like a home sick angel! Because it was tail heavy it came right at me just missing my face, i droped the power put loads of forward in and just saved it lol. At least yours would launch away from you & not at you!
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