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Old Nov 03, 2007, 02:43 PM
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Itzik Ronen's Avatar
Israel
Joined Dec 2004
234 Posts
FAQ
The Cularis will be my new FPV platform: What will be the best camera location?

Hi, Id like to use the Cularis (100 glider) as my new FPV platform: I dont like to see the prop in the video; Im considering the following options:
1. sticking the camera on a pole.
2. Putting the motor on a tower as a pusher and placing the camera in the airplane nose.
3. Placing the camera in the middle of the wing.
Do you, guys, have any suggestions/comments?
Thanks,
Itzik
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Old Nov 03, 2007, 03:07 PM
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AnthonyRC's Avatar
Switzerland
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Hey Itzik,
Personally I stuck with 1. and had some very good results.
I did 2. on my EasyGlider, and planned to do the same on the Cularis, but 1. worked so well, I never tried it.
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Old Nov 03, 2007, 08:13 PM
JettPilot's Avatar
Miami
Joined Apr 2005
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I would put the camera on the wing. You will get much less drag than with the other options. Putting the camera on a tower is horrible in terms of drag, and if your tower is not thick enough, it will move. The tower is also very fragile for transport .

Putting the motor on a tower is even worse. Lots of drag, has to be a pretty strong tower, lots of extra weight, and you will have bad pitch down with power, and pitch up as you take it off on a plane not designed for high thrust. The glide will be horrible and you will not like the way it flys

Put he camera out on the leading edge of the wing, maybe 1/3 of the way out or even less on the cularis , just enough to get the prop out of the picture. Drag will the minimal, its easy to build, results in lowest weight, and easiest transport. This by far is the best option. Use some 3 lead servo wire with a standard RC connector or mini deans connector to connect it GROUND, POWER, and VIDEO. All you do is one extra plug when you put the wing on. No need for large shielded video cable, I always use standard servo wire for video and never have had any problems .

JettPilot
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Old Nov 03, 2007, 09:38 PM
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Power Pod

If you were to streamline the mast and the power pod, use a spinner and a folding propellor, there would not be much drag.
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Old Nov 04, 2007, 12:19 AM
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Mangus's Avatar
United States, WA, Seattle
Joined Dec 2006
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Quote:
Originally Posted by tomsal
If you were to streamline the mast and the power pod, use a spinner and a folding propellor, there would not be much drag.
...not to mention that disruption of flow over the wing is likely more harmful to flight performance than drag above the lateral center of lift and gravity. All things considered, the drag of a .21" carbon tube is a minimal addition in comparison to the camera stuck to the wing setup, where the wing performs a rather vital function. The Cularis has less overall area than a larger gasser, although the aspect ratio makes up for the some of possible adverse affects.

There is no doubt that any of the options listed will work, though. I plan to mirror Anthony's setup with my (brand new) Cularis.
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Old Nov 04, 2007, 12:30 AM
Just trying to get a nut.
scrtsqrl's Avatar
United States, VA, McLean
Joined Oct 2006
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Quote:
Originally Posted by JettPilot
I would put the camera on the wing. You will get much less drag than with the other options. Putting the camera on a tower is horrible in terms of drag, and if your tower is not thick enough, it will move. The tower is also very fragile for transport .

Putting the motor on a tower is even worse. Lots of drag, has to be a pretty strong tower, lots of extra weight, and you will have bad pitch down with power, and pitch up as you take it off on a plane not designed for high thrust. The glide will be horrible and you will not like the way it flys

Put he camera out on the leading edge of the wing, maybe 1/3 of the way out or even less on the cularis , just enough to get the prop out of the picture. Drag will the minimal, its easy to build, results in lowest weight, and easiest transport. This by far is the best option. Use some 3 lead servo wire with a standard RC connector or mini deans connector to connect it GROUND, POWER, and VIDEO. All you do is one extra plug when you put the wing on. No need for large shielded video cable, I always use standard servo wire for video and never have had any problems .

JettPilot
JettPilot
All makes sense...sounds like a plan. But how do you protect it from the ground when you land? Is there enough visual clearance from the prop if you keep it inboard enough to be in the safe spot (the triangle created by the the bottom of the fuse, wingtip and wing root)?
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Old Nov 04, 2007, 01:07 AM
Fly FPV, sleep; repeat
twinturbostang's Avatar
Germantown, MD
Joined Mar 2006
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If you've seen pictures of some of Jett's planes, he embeds the camera into the leading edge of the wing. There is very little sticking out of the wing, and any disruptions to the airflow are probably minimized and are localized to just that one spot on the wing. On a big glider like that, I'm sure it won't know the difference. Having the camera built into the wing also protects it, except for the rare possibility of a point source collision with the camera lens.
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Old Nov 04, 2007, 03:36 AM
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Patsch, Austria
Joined Jul 2007
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I guess it all comes down what you exactly want to do with the plane

if streamline is first prority, to go super long range and have it as light as possible , embediing in the wing is probably the best

but if you want to use pan/tilt and want to have a nice look on your plane and your surrounding then I would go with the cf tube ot the motor pod...the cf tube doesnt even need to be very long, allready 10cm are looking much nicer...build it so you can adjust the length later, and be able to take it off for transport
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Old Nov 04, 2007, 08:21 AM
JettPilot's Avatar
Miami
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I have a Cularis that I am also building for FPV, my first electric in many years. It looks to me like the camera mounted about 1/3 of the way out on the wing would clear the prop visually, but I would have to measure to be sure.

If the camera is going to be fixed foward, the wing is a great option. Someone was concerned about disturbing the airflow over the wing, its not an issue. With such a large wing span, a camera on the leading edge will affect less than 2 % of the wings area behind it, which is nothing.

Trying to mast mount the camera would add a LOT more drag, and also be fragile and just a pain in the arse to transport and deal with. A camera cannot be allowed to shake around in the wind, so if you are thinking of just one small tube to mount it high, then you are going to be dissapointed in the video it produces.

IF you are going to do a pan, then that changes everything. If I were going to do a pan I would put it right on top of the canopy towards its rear, on its highest point, and just let the prop be in the picture while it is facing forward. ( Not high mounted ) If you have a folding prop, you can just shut the motor down for getting nice video foward. This is the camera position I will be using on my Cularis

Video TX will still be about 1/2 the way out on the wing on mine, I dont want any chance of RC intereference or reduction of my RC range...

JettPilot
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Old Nov 04, 2007, 10:32 AM
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Too much drag?

Jett,
If you are so concerned about drag why did you build an aircraft with so much drag. I saw the picture of your own design aircraft at the end of your windy day video and there is a big old engine without a cowling, landing gear hanging out without even wheel pants, equipment piled on both wingtips with no fairings to streamline it at all.

And you talk about too much drag.

Tom
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Old Nov 04, 2007, 01:35 PM
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AnthonyRC's Avatar
Switzerland
Joined Sep 2004
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Quote:
Originally Posted by JettPilot
...
Trying to mast mount the camera would add a LOT more drag, and also be fragile and just a pain in the arse to transport and deal with. A camera cannot be allowed to shake around in the wind, so if you are thinking of just one small tube to mount it high, then you are going to be dissapointed in the video it produces.
JettPilot
I'm sorry Jet, but I have to disagree... and that comes not from theory, but from a bird with over 100 flights to date.
The pylon has worked great for me, drag is not a problem whatsoever (I've floated with 4 other Cularises (Culari?) and this bird performs just as well as the rest.
As for fragility, I use the pylon to pick the plane up, I used a carbon fibre tube, inserted in an Alu tube which runs through the fuselage. Its probably the strongest assembly on the plane.
And last but not least... why would it shake around?, this thing is rigidly mounted to the fuselage.

The pylon has many advantages, I can't stand 80% cockpit/nose in FPV videos, and this lets me avoid that. The view of the plane from that viewpoint is marvelous. A 360 degree pan mount under development should offer some interesting possibilities.
Additionally, it lets me separate the Video Tx (that is on the pylon too) from the rest of the system.

The wing joiner and wing servo connections are in my opinion the weakest point of the Cularis design. I certainly wasn't ready to complicate that assembly by routing additional cables within the wing.

Here is a link to the maiden flight with this pylon arrangement (before I hooked up the pan/tilt servos) http://www.aeropix.ch/videos/CularisMaiden_3M.wmv
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Old Nov 04, 2007, 03:47 PM
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Mangus's Avatar
United States, WA, Seattle
Joined Dec 2006
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Quote:
Originally Posted by JettPilot
Someone was concerned about disturbing the airflow over the wing, its not an issue. With such a large wing span, a camera on the leading edge will affect less than 2 % of the wings area behind it, which is nothing.
Figuring 2" of the 100" (2%) is incorrect. Consider pictures of flow you've seen of an object flowing through air. Considering a reasonable width for a camera setup is 2", the flow disruption is going to grow as the flow moves rearward. By the trailing edge of the wing, it could easily double. Further, the inbourd portion of the wing has the most chord behind it. The chord at the root is 8", and 5" just before the tip break. This means that a larger percentage of area is affected. So, all in all, 2% is an underestimate. It's closer to a minimum of 6%, which is no longer insubstantial, in my opinion. At least not on an aircraft that's designed for efficiency vs. an aircraft designed to brute force its way through its surroundings.

Quote:
Originally Posted by JettPilot
Trying to mast mount the camera would add a LOT more drag
How would it add a LOT more drag? Twelve inches of .21" diameter carbon tube would add very minimal drag, and even better, what flow it does interrupt or turbulate is of minimal affect on any other vital aerodynamic surfaces.


Some of you seem to consider "streamlining" the action of moving drag-inducing bodies closer to the surface of the aircraft. Although in some cases this might be a good thing, in the case of the wing, this is mostly untrue. Consider a spoiler. If I were to extend some of the logic in this thread, a spoiler would be most effective if I were to put it on the end of a boom, rather than on the surface of a wing. But spoilers do more than just introduce frontal area, so this logic breaks down. This is no different with a camera mounted to the surface of a wing vs. on the end of a boom. On the end of the boom, the minimal drag added by the boom is negligable compared to the flow spoilage potentially induced by the camera on the wing.

Finally, the Cularis wing is barely thick enough for a mini servo. I don't think anyone will be embedding their camera into the wing.

Again, this isn't to say that mounting the camera on the wing doesn't work. It absolutely does! This will likely work fine for those who prefer it. I just want to make sure it's not justified with false logic.
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Old Nov 04, 2007, 03:50 PM
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Itzik Ronen's Avatar
Israel
Joined Dec 2004
234 Posts
Thanks guys,
I tried the option of moving the motor to the back, on my EasyGlider just before disassembling it for the Cularis. Jett youre right, I didnt like the flight characteristics. The plane was heavily loaded but this was not the reason why I didnt feel comfortable flying it. Anyway, I dont like to take a very well designed plane and mess it around.
Jett, Im not really sure about the wing idea: though Im familiar with your work and really appreciate your experience. I remember the long range FPV discussion and Im going to place my video Tx on the wing this time but not the camera. Id like to use pan and look around.
Because of the huge amount of electronics rig Im carrying the prop is most of the time 15-30% on, so the canopy mount is not a good option.
So the best option left for me is using a stick: I can deal with the transportation problems; lowering the drag with a reasonable aerodynamic shape, is not a problem! So I have to pay attention to the vibration issue!
Ill go with Anthony; Guys, if Ill solve all this: do you believe it is the best setup?
Itzik
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Old Nov 04, 2007, 04:09 PM
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Patscherpofel's Avatar
Patsch, Austria
Joined Jul 2007
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Quote:
Originally Posted by Itzik Ronen
if Ill solve all this: do you believe it is the best setup?
Itzik
wow...this looks a bit heavy ...thats an intresting camera you have there
looks like the big brother of the kx131
maybe have he motor pylon more in front? maybe that helps a bit
also I like to have my rc rx more isolated, so its the last thing in the plane

about the stability of the cf tube...I know you like DS, so be sure to have it fit tight
mine starts to shake if I dive straight down about 100m...but I didnt really build it that well...shouldnt be a problem if its well done
but the aluminum tube that takes the cf tube is a soild thing...also easy to remove if you dont want to fly with camera
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Old Nov 04, 2007, 05:08 PM
jab
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Joined Aug 2007
1,081 Posts
The trick with placing engine over the wing, is to make sure it is located close to CG. Slightly behind the CG can also be a idea to compensate for the engine pushing from above, but compensating with correct propeller angle is the best approach in my experience. Pusher design can also be an idea, since it's easier to make the engine mount aerodynamic that way.
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