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Old Oct 13, 2009, 03:09 PM
Engineer for Christ
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Amherst, VA
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Scout FPV - First person view soaring plane

Gliders and high altitude planes are always relaxing to fly. And since the camera equipment for first person view is more expensive than any one plane I have built, I figured I would build a second airplane.

Basically I wanted a platform that was extremely versatile and still capable of FPV. I also wanted something good for high altitude soaring as well as low altitude flight. The Scout is what I came up with. It is a dual boom design with the motor in the middle of the airplane, right between the booms.The reason for the center motor is to keep the prop behind the camera so I can have a full view. I will hopefully be incorporating pan and tilt on the camera so I can look around while in flight. It will resemble the Bell XP-52 and the Saab J21, except this is more of a glider, where the J21 and XP-52 were fighter plane designs.

This airplane should be able to accommodate a second battery for longer flight times without affecting it's handling too much. I also wanted room for things like a bomb bay door. Wouldn't it be fun to make a dive bombing run looking out the cockpit?
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Old Oct 13, 2009, 03:17 PM
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Amherst, VA
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Making the wing

I settled on a 62" wingspan for this model. That should allow for very stable flight. It should allow for good high altitude soaring and sweeping low over the tree tops

The airfoil is a USA 49. It is a flat bottom airfoil that should provide a fair amount of lift, but it is thin to allow for higher speeds. I also swept the wing backward for two reasons: 1. It moves the CG toward the rear of the airplane since there won't be a heavy motor in the nose. 2. It looks cool

The wing was fiberglassed with 1.5 oz cloth and Wset System epoxy. I added a triangular stress member to the top of the wing where the fueslage and booms will be attached. The added fiberglass is to resist the natural torsion of the wing that occurs with this dual boom design.

Unfortunately, this wing is heavy. It weighs in at 15 oz I might make a second lighter wing later.
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Old Oct 13, 2009, 03:26 PM
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Amherst, VA
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Designing the tail

The problem with a dual boom is tail weight can add up really fast. Rather than have one single unit running to the tail, this model has two. Therefore I needed to make the booms as small as possible. In previous models I noticed that carbon tubes tend to twist around, so I decided on balsa sheeted foam. I simply cut out four templates and secured them to blue EPS foam with super 77 adhesive.

The booms are 23" long X 1-1/8" tall X 1-1/4 wide. The front is cut as a Clark Y airfoil to reduce the drag of the boom. Together they weigh only 1.8 oz and are fairly stiff. They will be mounted 13.5" apart giving me plenty of room for a propeller up to 11", although I plan to fly only an 8 or 9".

The horizontal stabilizer and elevator are made of 1/8" balsa. Hopefully the air off of the prop won't be strong enough for adverse flex.
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Old Oct 13, 2009, 03:34 PM
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Amherst, VA
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The fuselage

The fuselage will support the motor, camera, and the batteries. The battery will be mounted in the very front of the airplane for nose weight with the video camera mounted directly below it. A second battery should I choose to fly one will be mounted in the bottom of the fuselage at the airplane CG.

Again I opted for balsa sheeted foam for the construction. The fuselage measures 26" long X 3" tall X 2.25" wide. It weighs 3.3 oz. I will hollow out the nose for the battery and camera later. I still need to receive the camera in the mail. I should have plenty of room inside the fuselage for all of the equipment... I hope.

-Alex
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Old Oct 13, 2009, 06:50 PM
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Alex,
you need this.

http://www.servocity.com/html/spt50_...an___tilt.html
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Old Oct 13, 2009, 07:26 PM
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Nice find!
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Old Oct 14, 2009, 09:29 AM
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Excellent find Jack! It gives me a few ideas on how I will do my pan/tilt. Unfortunately I'm only allowing 2" height for the whole mechanism including the camera. I'm planning on putting the pan servo on a hinge which will move up and down via the tilt servo. The camera will be mounted on the head of the pan servo.

The other way I was thinking of doing this is to make a U-shaped pivot for the camera. I would mount both servos behind the bracket and mix them together to move the camera around. That way I am less likely to strip a servo. Unfortunately, I haven't figured out how to make the tilt linkage work yet for that set up.
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Old Oct 14, 2009, 09:47 AM
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My camera mount will be an inverted version of the Pandora tilt kit I want to mount it from the top of the airplane and not to the bottom. The hinge will be at the top so in the event of a servo failure the camera will naturally rest upright so I can see to fly home.
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Old Oct 16, 2009, 12:17 AM
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Painted and covered

I painted and covered the airplane. I still need to mount all of the electronics, but for some reason I decided to cover it first. I went with a black and neon red color scheme so in the event I lose the camera, the plane hopefully won't be hard to see so I can bring it back.

I also got my camera in this morning. I chose the 171 CCD camera from dpcav.com. I chose it because it was small and worked in lower light. I mounted it to the pan servo. I'm not certain what I want to use for the hinge for the tilt just jet.

The AV equipment is going to add about 8 oz to the weight of the airplane The camera and pan/tilt weigh 2 oz. The transmitter and antenna weigh 2 oz. And an 800 mAh 3S lipo is another 2 oz. I also need to figure in another 2 ounces for cables, GPS, and the OSD unit. So the weight on this one is adding up really quick.

The airplane's AUW without the video equipment is going to be about 42 oz. Add in the 8 oz for the video and it comes out to be 50 oz. I also plan on making this one capable of carrying a second battery for a fully loaded weight of almost 58 oz! This will make it the heaviest airplane I have ever owned However, the wing is 3.8 square feet in area, so the wing loading will be around 16 oz/ft which isn't too bad. With a single battery it will be 14 oz/ft. Without video equipment that number drops to 11 oz/ft, which is equivalent to my lighter aircraft. I just hope I have enough motor to get this thing up in the air. I might need to up size that too.
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Old Oct 16, 2009, 01:02 AM
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Sweet bejebers.... My EasyStar with everything in it was only 32oz.
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Old Oct 16, 2009, 01:25 AM
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Amherst, VA
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Quote:
Originally Posted by HappyKillmore
Sweet bejebers.... My EasyStar with everything in it was only 32oz.

When you add in 1.5 more square feet of wing + 2 more batteries + a larger motor + pan and tilt, it adds up. This airplane is freaking huge. I can fly it as light as 48 oz with camera on board which puts it at 13 oz/ft, which is fairly light.
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Old Oct 16, 2009, 09:38 AM
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Here's the wiring for future reference Alex



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Last edited by HappyKillmore; Oct 16, 2009 at 02:07 PM.
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Old Oct 16, 2009, 02:04 PM
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My el-cheapo camera came in the mail today.

My initial testing in my hobby room sure looks good! Picture quality looks excellent for 1/3 the price of my KX-191
http://cgi.ebay.com/ws/eBayISAPI.dll...=STRK:MEWNX:IT

I also puchased a super wide lens (2.1mm)
http://www.rangevideo.com/index.php?...products_id=27
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Old Oct 16, 2009, 03:02 PM
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Amherst, VA
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Pan and tilt mechanism completed

Here's the pan and tilt mechanism I came up with. Hopefully it won't be too shaky. When the camera is in the down position it has some play in it. I might add a support to stiffen it up some.

My pivot goes from 0 to 50 degrees in the tilt and has 120 degrees of swing in the pan side to side. That should be more than enough for me. The tilt mechanism is very similar to a typical aileron set up. I simply use 2 Du-Bro hinges to make the pivot. I also made it detachable so I can sitch it between different airplanes. This set up should fit my high altitude aerial photography plane as well. With a little modification, it should fit my gliders too.

The camera is shielded from the sun by the fuselage and will be well protected by the fuselage in a crash. I still don't know where I'm going to mount the TX and antenna yet.

I'm now mounting the rest of the servos and the ESC. Once that is all set up, I'll figure out where to mount the TX and antenna.

-Alex
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Old Oct 16, 2009, 03:06 PM
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Amherst, VA
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Quote:
Originally Posted by HappyKillmore
My el-cheapo camera came in the mail today.

My initial testing in my hobby room sure looks good! Picture quality looks excellent for 1/3 the price of my KX-191
http://cgi.ebay.com/ws/eBayISAPI.dll...=STRK:MEWNX:IT
Does that one come with a protective shell, or is it exposed? Also, how heavy is it? Mine feels oddly heavy weighing in at 1.2 oz. How is it in low light? Perhaps I should buy one of those to fit in my Snyper? That way I wouldn't need to switch out cameras.
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