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Old Oct 12, 2014, 04:13 PM
Olivier_C is offline
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Carbon 335mm FPV racer with scale schematics : Prophecy 335


I'm building a new copter, a "FPV racer", the purpose for this one is to go fast, very fast, and low, very low.
Distance between motors is 335mm, it's a tiny bit larger than it's long, to avoid airflow against the frame.

I'll be re-using the same power plant as my current acro quad (build thread: https://www.rcgroups.com/forums/show....php?t=2149283).

I name it the PROPHECY 335.
335 because of 335mm between motors, and prophecy because I said so ;]

--- Gear :

Motors : Tigers MT2208-18 1100kV (link)
ESCs : Tigers T30A (link)
Propellers : HPprop 8x4.5MR or HQProp 8x5 (link)
Battery when FPV : 3S-2200mAh 35C Nanotech
Battery when line-of-sight : 4S-1800mAh 25C Nanotech
Flight controller : HK clone of the Crius AIOP, running Multiwii 2.3 dev build(link)
FPV : Boscam 5.8GHz 400mW and Spironet antenna (link)

--- Parts for the frame :

- 2x 300x100x1.5mm wooven carbon (link)
- 10x 45mm aluminium spacers (link)
- HK450V2 landing skid (link)
- 10x10 aluminium square tube
- 10x10 aluminium corner
- Few dozens of M3 hex screws and washers
- ...

--- 1:1 printable PDF (A4) : Click HERE

--- Screenshots :







Last edited by Olivier_C; Feb 06, 2015 at 11:45 AM.
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Old Oct 12, 2014, 04:14 PM
Olivier_C is offline
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Printed 1:1, taped to some 300x100x1.5mm carbon sheets (Hobbyking.com)



I tape the underside of the carbon sheet so it stays nice and shiny.



With a cutter I trace around the paper...



Simple rig I make to cut the sheets.
I avoid using tools such as the Dremel to cut carbon, it's making nasty dust.
With a simple hand saw it's working fine and (almost) clean.
Just make sure you say goodbye to the blade, because that will be its last voyage.



Bottom plate is cut, easy shape :

Last edited by Olivier_C; Feb 05, 2015 at 08:51 AM.
Old Oct 12, 2014, 04:14 PM
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After a good 30 minutes of effort, top plate is also completed.
Then some quick sanding on the edges :



Do not try to vaccum clean the carbon powder, it will ruin the machine.
Just throw into a bag, and also trash the cardboard.



Putting the 1:1 drawings back on the 2 plates to locate holes :
I pre-drill through the paper.



All drilled M3 :



Putting some temporary nylon spacer for a dry fit.
Final aluminium spacers (30, 37 and 45mm) are in the mail, should be here soon :



Next step, the arms, aluminium square 10x10x1mm :



These blue washers are looking great, but too tall for my taste, I'll find something better :



Using a mix of nylon and steel screws to create weak links.
The big hole is for the C-clip under the 2208 motors.



It's almost looking like a copter now :]



These spacers are too small for now, a Gopro3 will have to fit there, and it's 41mm tall.
Plus 2mm top and bottom for some foam, and that's a total of 45mm between the 2 plates :



Testing the look with 8x4.5MR HQprops :



Can fold for transport or if a M3 nylon screw fails during a crash.
Maybe.



To be continued !
Last edited by Olivier_C; Feb 05, 2015 at 08:54 AM.
Old Oct 13, 2014, 12:20 PM
n-2-stuff is offline
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Scott
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Great job Olivier ! I mite build one myself. My old BAH frame is still holding together, but it's on it's last legs. I want something a little bigger so I don't have to cram all the parts between several plates. Your design is clean and simple and easy to find materials.

Scott
Old Oct 13, 2014, 12:24 PM
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Stoked. Looking great man.
Old Oct 13, 2014, 01:01 PM
Olivier_C is offline
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Thanks guys,I worked a bit on the quad today, will post new photos later.
Also I'll post the 1:1 drawings as soon as possible, I didn't posted these right away because I make tweaks during the build when I get new ideas or there's things that worked on paper but are not practical in real

Right now I'm trying to find a clever way to have an option so it could tilt the Gopro up during high speed forward, that's a thing I noticed when I strapped the camera to my acro quad, it was so angled I could not reach the maximum speed because all I could see was the ground...
Old Oct 13, 2014, 02:24 PM
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Quote:
Originally Posted by Olivier_C View Post
Thanks guys,I worked a bit on the quad today, will post new photos later.
Also I'll post the 1:1 drawings as soon as possible, I didn't posted these right away because I make tweaks during the build when I get new ideas or there's things that worked on paper but are not practical in real

Right now I'm trying to find a clever way to have an option so it could tilt the Gopro up during high speed forward, that's a thing I noticed when I strapped the camera to my acro quad, it was so angled I could not reach the maximum speed because all I could see was the ground...
The way the mini quads do it by making a pivot mount for their camera and using the tilt function from the controller. It's just a servo and small peice of wire to the camera. Only problem I see you will be tilting a Gopro not a board camera.
Old Oct 13, 2014, 04:00 PM
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Yep I tried to find something like that, but was not great, I'll leave this aside for now.

More works,

Now adding the "Gopro armor" :



Quicky found that I have to cut like this so I can slide the camera inside, design oversight



All these nylon spacers are temporary, still waiting for the aluminium ones :
I'll let this front as is until I get all the parts.
I'll probably add an extra carbon plate to protect the camera.



The lipo holder, this is a bit overengineered, but I like the lipos well attached so it does not cause havoc in a crash :



With M3 nuts inbetween so the velcro can move freely.
2 holes in the bottom plate would be much simpler and lighter, but aluminium like that is very light, and I want to avoid anything outside of the 2 plates.



Took the "brain block" direct from my acro quad, the flight controller is the Crius AIOP clone sold by Hobbyking, and the receiver is a FrSky TFR8, compatible with the FASST on my Futaba. And a 250mW 5.8GHz video transmitter for now, and there's a 400mW in the mail that should be here soon. It's short enough to fit vertically insidethe frame, but I may have to resolder the 2 plugs.
The casing is not really needed for the flight controller, but that's not too heavy, and this quad won't have an easy life so... I keep it.



Next step will be to adapt the power harness so it fits nice and tidy inside the frame !

Last edited by Olivier_C; Feb 05, 2015 at 08:56 AM.
Old Oct 13, 2014, 04:20 PM
n-2-stuff is offline
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Scott
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And don't forget a front stop for the battery once you get the CG right.
Old Oct 14, 2014, 12:10 PM
helinor is offline
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Nice touch again Olivier. I will follow this
Old Oct 15, 2014, 05:50 AM
renatoa is offline
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For those not so skilled, you can get something very close as appearance, glass fiber, and stinking cheap, $10, form HiModel, it is called spider mini.
Is my current workhorse for 6 months and not intending to replace too soon.
I am using sunrise slim ESC, that fits insider arms, giving to the whole setup an even "wireless" distinctive touch
Check for picture of electronic wiring in the central area and weight without battery in my attachments.
Last edited by renatoa; Nov 15, 2016 at 02:16 AM.
Old Oct 16, 2014, 04:13 AM
Olivier_C is offline
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Yep I'm not pretending to build anything revolutionary, it's been done before, and will be done after

At first I wanted to make a design a bit "different", I studied a double inverted V, with the arms open to the front like this : <<, then with the motors up-side down, etc, but in the end it was adding complexity for no real benefits, so I sticked to a good old X kind.

There's plenty of frame like this available on the market, it's just that when you build it yourself, it doesn't fly the same
Old Oct 16, 2014, 04:19 AM
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More photos !

The easy way to pair ESCs...



And I forgot the plug for the video transmiter GRRRR!



Received the 45mm alu spacers, build quality is nice, and to my surprise that's real light aluminium, not a crappy alloy.
The GoPro slides in between foam, that's insulant foam pre-glued (Armaflex)



Then it rests against the spacers, I'll add a bit of foam there, and also to protect and lock the front of the camera I've got an idea but I'll test and see if it works first



Weight of the frame naked is 175grams, and about 20gr more with the landing skid.
Could gain weight if needed, without these fat blue washers, and making the lipo holder simpler, etc, but given the powerplant I'm not too worried, a little extra weight could even help.

Last edited by Olivier_C; Feb 05, 2015 at 08:57 AM.
Old Oct 16, 2014, 04:25 AM
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From the side it's looking squarishly cute



Belly of the tiny beast.
I went for a landing skid, not much because of the landing and take-off stuff, more for protection.
This kind saved my bigger 450mm quad many times, excellent shock absorber, and also let you slides on hard grounds and avoid the nose or props touching first



Only have to fit the electronics, and it's good to go !

Last edited by Olivier_C; Feb 05, 2015 at 08:58 AM.
Old Oct 16, 2014, 04:32 AM
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I would reverse the back skid leg, to have a bigger landing base.


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