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Roban 700 AH-1W Super Cobra Build

F106DeltaDart

Well-known member
#2
The first step in the build was to get the front turret operational. Before I could tackle the pan/tilt, I wanted a way to spin up the rotary cannon. Ended up building it out of spare parts. The cannon assembly is mounted on 2 Trex 450 bearing blocks and a piece of the main shaft. It is run by a retract motor out an old HobbyKing gear. Works like a charm so far! In order to mimick the finish of the barrels, I painted them with a high-heat grill paint. This gives the gun the same off-black flat color as the real barrels.

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F106DeltaDart

Well-known member
#3
I am continuing work on the gun turret at the moment, and finished up adding the servo for gun elevation. Used a 5 gram servo that barely fit inside the housing and some old Trex 450 ball links to get it working. The movement range actually mirrors the real thing pretty closely. I also cut open the bottom of the turret, as the real is open as well for maintenance and ejecting casings. I’m still debating whether to add the cover plate on the turret or not around the barrel. In the States, it is kept on, but it is usually removed in combat environments for accessibility to the gun.

One other thing I’m still trying to change is a mechanism to trigger the gun barrel rotation. As of now with the retract motor board, the barrel spins for 4 seconds when triggered. I am planning on tying the gun motor to a receiver activated switch that I could use to trigger it. I put in an order for this, hopefully it does the trick: https://www.amazon.com/gp/product/B07BKSGW3D/?tag=lstir-20
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F106DeltaDart

Well-known member
#4
Still waiting on a 180 deg servo for gun azimuth. This will also tie to the FLIR so that the movements are synchronized. Tomorrow I’ll start to work on getting the mechanics together. I also started some detail work on the FLIR. I couldn’t stand the black painted lenses, so I cut out the left opening, and added some clear plastic with a mirror film on the right. For the left side, I’m hoping to embed a tiny whoop FPV camera inside for an observer to operate. They would be able to control the gun and FLIR during flight. Should be great for handing off to kids and friends during fun flys.
 

Attachments

F106DeltaDart

Well-known member
#6
Thanks Crawford! I got the servos installed today as well as the helical gear upgrade. The 2 outer servos needed an 1/8” plywood shim, and the center required a 1/4” shim to fit properly. In the manual, it strongly recommends using metal servo horns. Does anyone who’s built one of these have any experience whether this is the case? In that case, any recommendations for a metal arm for the MKS 665 would be greatly appreciated.

I also received the tiny whoop camera from GetFPV. I didn’t realize just how small this thing was! It will fit in the FLIR with plenty of room to spare, and is actually very close to scale with the real FLIR camera!

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Attachments

#8
Thanks Crawford! I got the servos installed today as well as the helical gear upgrade. The 2 outer servos needed an 1/8” plywood shim, and the center required a 1/4” shim to fit properly. In the manual, it strongly recommends using metal servo horns. Does anyone who’s built one of these have any experience whether this is the case? In that case, any recommendations for a metal arm for the MKS 665 would be greatly appreciated.

I also received the tiny whoop camera from GetFPV. I didn’t realize just how small this thing was! It will fit in the FLIR with plenty of room to spare, and is actually very close to scale with the real FLIR camera!

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There's no scratch building a helo is there?
 

L Edge

Well-known member
#11
I am continuing work on the gun turret at the moment, and finished up adding the servo for gun elevation. Used a 5 gram servo that barely fit inside the housing and some old Trex 450 ball links to get it working. The movement range actually mirrors the real thing pretty closely. I also cut open the bottom of the turret, as the real is open as well for maintenance and ejecting casings. I’m still debating whether to add the cover plate on the turret or not around the barrel. In the States, it is kept on, but it is usually removed in combat environments for accessibility to the gun.

One other thing I’m still trying to change is a mechanism to trigger the gun barrel rotation. As of now with the retract motor board, the barrel spins for 4 seconds when triggered. I am planning on tying the gun motor to a receiver activated switch that I could use to trigger it. I put in an order for this, hopefully it does the trick: https://www.amazon.com/gp/product/B07BKSGW3D/?tag=lstir-20
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What radio do you have?
If you have a DX9, there is a new segment called a sequencer which you can add a program that would allow you to flip a switch or flight mode to keep rotating the gun turret or shutting it off. It allows you to uses the servo to set the limits of rotation and even backtrack even in the process. I do agree it is a pain to figure it out, but it is cool.
I made a sequencer for my transport by using a 3 Flight mode setup. 1) servo stayed in no brake situation for t/o, flight, and landing. 2) Servo moved and locked wheel for allowing runup. 3) servo oscillated continiously against brake so you could taxi (you adjusted brake by changing servo arc) nice and smooth.

Did you do anything yet with the XC-142?
 
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F106DeltaDart

Well-known member
#13
What radio do you have?
If you have a DX9, there is a new segment called a sequencer which you can add a program that would allow you to flip a switch or flight mode to keep rotating the gun turret or shutting it off. It allows you to uses the servo to set the limits of rotation and even backtrack even in the process. I do agree it is a pain to figure it out, but it is cool.
I made a sequencer for my transport by using a 3 Flight mode setup. 1) servo stayed in no brake situation for t/o, flight, and landing. 2) Servo moved and locked wheel for allowing runup. 3) servo oscillated continiously against brake so you could taxi (you adjusted brake by changing servo arc) nice and smooth.

Did you do anything yet with the XC-142?
I have an IX20, but will be using a DX9 as the "gunner" radio. The sequencer feature is great for servos and such, but it doesn't turn power on/off to the channel. It just changes what command it is sending through the signal wire. I ended up adding one of the relays to spool up/down the gun barrel: https://www.amazon.com/gp/product/B07BKSGW3D/?tag=lstir-20. It now spools up when I hold down a button, and stops when I release it.
 

PsyBorg

Wake up! Time to fly!
#15
Thats gotta weigh a ton with them 3 massive packs on it. Almost looks like it would grind the flir turret in flight but I know different. CG on them things is super tail heavy with the long booms and need that lump o battery.

Cant wait to see the body on it and some full dress flight footage.
 

F106DeltaDart

Well-known member
#16
Thats gotta weigh a ton with them 3 massive packs on it. Almost looks like it would grind the flir turret in flight but I know different. CG on them things is super tail heavy with the long booms and need that lump o battery.

Cant wait to see the body on it and some full dress flight footage.
It is definitely a chunky machine at this weight, but it still seemed to fly pretty light. Two of those packs are flight batteries, the other 2 are just there to simulate the weight of the fuselage. Running 1300rpm right now, and pulling 14A in a hover. Should fly a good while on 12S 5800 packs.
 

PsyBorg

Wake up! Time to fly!
#17
Wow them fuselage's weight that much? Hrmmm I guess so then as it is not exactly a micro heli by any means hehe. That hovers on a little less current then the 3 inch quad I just built does. Should be pretty efficient as its not meant to do 3d and will just fly scale in "cruiser" mode.

That all said why you on the forums yakkin at me and not putting that fuse on :geek::LOL: