Building the Raven 234mm Acro Quad from FreeBirdRC

If you want to be a good multicopter pilot, you you should be practicing multicopter acrobatics. Learning how to do flips and rolls, and how to fly fast patterns, and how to do high full throttle punch outs, etc, is a whole lot of fun to do. Practicing with an acro machine might also save your expensive aerial photography setup some day.

When you practice acro flying, you learn how to recover your copter when you accidentally get it upside down or into some other unintended attitude. Acro flying also teaches you how to stay visually oriented with your machine, and how to quickly get re-oriented when one of those inevitable "Oh snap, which way is it going!" moments occur.

Acro flying will also teach you to fly comfortably and confidently without the aid of self leveling and other auto pilot functions. If you have read a few of the threads about "fly aways", you know that the most common advice, should your machine start to fly off on it's own, is to switch to manual (all flying aids turned off) mode. Manual mode wont save your craft if you haven't learned to fly without the auto pilot functions turned on.

The best way to quickly learn to be a better acro pilot, is to start with a quality frame that will take a good pounding without breaking all of the time. When you aren't afraid of crashing, you will push yourself more and learn much faster.

A very good example of a tough, crash resistant quadcopter frame designed specifically for flying speed and acrobatics, is the Raven 234 mm quadcoper by FreeBirdRC.com. Read on, and we will build a high performance acrobatic quadcopter based on the Raven 234 frame.

Frame Description:

234 mm motor to motor, diagonal measurement, max prop size 6"

4mm all carbon arms

2mm all carbon centerplates and FC protecion plate

Complete hardware set included

Recommended setup:

Motor: Sunnysky X2204 2300kv

Esc: Eagle 12A SimonK RapidESC by FreeBirdRC.com

Flight Controller: Swift Pro MWC by FreeBirdRC.com

Lemon Satellite Receiver

Battery: 1300mah 3s 30C 

Propeller: FC 6x4.5

Unfortunately, I don't have any decent video yet of one of my 234mm Raven frames flying hard acro. Here is some video of the Raven 234's bigger brother, the Raven 320, doing what it does best. If you want to see video of some seriously hard core acro flying, go to Vimeo or Youtube, and search for videos from names like Quadmovr or Boostabeats.

That was not me doing the flying in that video. I'm not quite that good yet, but I am quickly getting better! (Thanks very much to Justin Pryde for providing the video.)

The secret to quadcopter acrobatic success is to start with the right frame, like the Raven 234mm all carbon sport/acro frame from my new store, FreeBirdRC.com. Inspired by other acro quadcopter designs I found on the internet, I designed the Raven 234mm to be as strong, lightweight, and stiff as possible.  The amount of abuse these frames can withstand is amazing. When you start practicing multiple flips and rolls at low altitude, and/or at high speed, you WILL crash. Fortunately, crashes are no big deal when the worst that usually happens is a broken prop or two, and then you go right back to flying (and crashing!) again. 

The Raven frame is so tough because it is made from top quality pure carbon fiber. Each part is made from many layers of super strong, super stiff uni carbon mat. The outer surface of each part is finished with a gorgeous carbon fiber twill weave. The result is the lightest, strongest, stiffest frame possible.

When outfitted with the right flight controller, motors, speed controllers and battery, the performance of this little speedster simply has to be seen to be believed. Lets get building!

Start by preparing the Eagle 12A speed contollers.

Carefully remove the heat shrink tubing from the ESC by slitting the tubing from the BOTTOM. Don't discard the shrink tubing, we will re-use it later. Remove the tubing and set it aside for later also. Do this for all four ESC's.

Use a soldering iron to remove the black and red wires from the power supply side of the ESC, and also remove the three black motor wires from the motor side of the ESC. Save the red and black power supply wires. We will re-use them when we make the power wiring loom later.

Remove the red and black flight control connector wires from three of the four ESC's. The wires will slide out of the connector easily if you raise the retaining tabs with the tip of an exacto knife. 

Depending on your flight controller choice, you may need to remove the connector from the three single white wires, and then cover them with heat shrink tubing for insulation. If you install the reccomended Swift Pro board with low profile pin installation (this will be covered later in this article), you will need to do this step.

 Set the esc's aside for the moment, and temporarily assemble all four arms to the bottom center plate as shown. I like to use 3mm nuts for this temporary step. You could also use the black rubber grommets that come included in the Raven 234 frame kit. Don't use the 3mm nylocks that come with the frame kit yet. They are too hard to get on and off.

Drop the other center plate right on top of the temporary nuts as shown. This establishes a reference for positioning the ESC's. Leave about a 1/8" gap between the edge of the centerplate and the end of the esc's. Temporarily lock the ESC's into position with some zip ties.

The next step is to make the wiring loom from some 16awg and 20awg wire.You can re-use the 20awg wire you removed from the esc's earlier. If you happen to have a retired lipo pack with 16awg connector wires, you can salvage the wire (and the connector !) to make your loom. If you need wire, you can purchase high quality pure silicone wire at FreeBirdRC.com.

You can watch an excellent video on Vimeo that details how to make the wiring loom here.

 Remove the top center plate and the temporary 3mm nuts. Carefully arrange the wiring loom as shown. 

Replace the top center plate, and install the temporary 3mm nuts again. You must be very carefull not to pinch any of the wires between the plates and the arms. Start with the nuts turned down just far enough to gently hold the loom in place. A popsicle stick makes a good tool to help move the wires out of the way, as required. Snug down one nut at a time as you get the wires around it positioned. When finished, double check again that the plates and arms are firmly sandwiched together with no pinched wires.

The next step is to solder the loom to the ESC's.Trim the black and red ESC power leads from the wiring loom. Make them just long enough to reach the solder pads on theESC's, without being too tight.

The next step is to trim the motor leads, and solder them to the ESC's. Start by temporarily mounting the Sunnysky X2204 KV2300 motors. 

Trim the motor wires to be just long enough to easily reach the solder pads on the ESC's.

The ends of the motor wires need to be pre-tinned with some solder. It is easier to do this with the motors removed from the frame. Note that the section of wire you expose for tinning will be coated with enamel. It takes high heat and a little time to burn away the enamel before the solder will stick to the wire. Applying a little flux might help. Be sure that the wires have a good coat of tin on them before you attempt to solder the wires to the ESC's.

Re-mount the motors to the frame, and solder the wires to the ESC's. The front right and rear left motors will get the wires attached as shown, with the wires going in straight lines from the motor to the ESC's. The front left and rear right motors will need to have have the solder positions for two of the motor wires swapped, in order to reverse the direction the motors will spin.

When all the wires are soldered to the ESC's, the heat sinks and  shrink tubing can be replaced on the motors. Set the heat sink in place, and unbolt the motor from the frame one more time.

Put the heat shrink tubing back around the ESC and heat sink, and close off the slit in the shrink tubing material as much as possible.

Seal the the slit in the heat shrink wrap with a piece of black electrical tape.

Mount the motors back on the frame. The build is almost complete!

Swap out the temporary 3mm nuts that are holding the frame together, with the 3mm nylocks that come with the Raven 234 frame kit. Do this by swapping just one nut at a time, while keeping the rest of the hardware firmly bolted to the frame. This will prevent the frame from loosening up and allowing the wires to move and get pinched.

Thread the ESC to Flight controller signal wires through the openings in the frame as shown.

Note that I have also swapped out the black anodized bolts for stainless steel. I think the stainless steel provides a nice contrast to the black carbon frame, and just looks better. The frames are shipped with stainless hardware.

Solder on your choice of battery connector. Lock down the ESC's with some zip ties.

Install the Swift Pro flight controller, with ultra low profile pin configuration next. This pin configuration, combined with a Lemon satellite receiver, results in the lightest, most compact, and low drag setup possible. See the Swift Pro product page at FreeBirdRC.com for more information on this configuration.

The ESC to flight controller leads from the ESC's are inserted into the bottom pins on the Swift Pro board as shown. Place a set of rubber grommets (Included in the Raven 234 frame kit) onto the center frame bolts.

Set the Swift Pro board in place on the frame. As you are placing the board, If you give the board a turn to wind up the slack in the esc leads, the lead wires will fit nicely out of the way under the board.  Make sure that the mini usb plug is facing the front of the quad. If you are NOT planning to use the included carbon flight controller protection plate, add another set of grommets and then finish the board installation with 3mm nylocks. If you ARE going to install the protection plate, omit the second set of grommets and nylocks, and install the four black nylon standoffs that come with the Raven 234 frame kit.

You'll need to make an adapter cable to connect the Lemon satellite receiver to the Swift Pro board. Make it by splicing a standard male servo lead to a satellite connector lead.

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 Connect the adapter cable, and fix the satellite receiver to the top of the Swift Pro board with a little hot melt glue. To protect the antenna wires from getting broken off, also use some hot melt glue where the antenna wires exit the receiver.

If you are going to use the flight controller protection plate that is included with the Raven 234 frame kit, go ahead and mount it to the frame now. It's a very good idea to use the protection plate. It might save your flight controller and receiver in a crash. The disadvantage is a little extra drag in flight, and a slightly less "lean and mean" looking quadcopter.

Almost done! The last step in the build is to install the battery strap. Start by putting a strip of velco on the bottom of the frame as shown.(Put a corresponding strip of velcro on the bottoms of your flight batteries.)

Thread the battery strap between the center plates as shown. The strap is not included in the Raven 234 kit. You can find straps like this from several different Ebay vendors. The one used here is 10" (260mm) long.

When cinched up tight, this strap, combined with the velcro on the bottom of the frame, will never let go of your battery in flight.

It's done! Put some props on the little guy and go fly some acro with it!

Here are my current multiwii settings for the Raven 234 with Swift Pro flight controller. They may not exactly suit your quad and flying style, but they should provide a decent starting point.

I hope you enjoyed this build article. As you can see, putting a Raven 234 together is a pretty straighforward task. I really hope you will consider giving one a try! Flying acro with a purpose built acro flying machine is not only a challenge to your multicopter piloting skills, it's also just a whole, whole lot of fun to do! The more acro you fly, the more confident and proficient you will become as a pilot. The increased flying skills you develop while flying acro will pay off, no mater what kind of multicopter you choose to fly.