V90 FBL SK720 Build

[R0t0R]

UPS finally got here with my Velocity 90 kit! Capi has the build thread pretty well covered, so I won't duplicate that here. Will post any differences I run across in the FBL kit.

Here's what's going in it:
SK720
JR8717s on cyclic (until higher torque TORQs are out)
TORQ 9088 on tail
TORQ 9080 on throttle
MultiGov Pro
YS91SR-3DS
Outrage pipe
Edge 693 FBL mains
Edge 105 tails
Outrage 5000 RX pack
Running straight 8V with a Perfect Regulators fail safe switch

Off to the workshop to start the build on this bad boy! Will post more as the build progresses.

At first glance, the V90 looks a little more "Boxy" than it's V50 and G5 brothers!

[Foxden]

Dude,

It's not built yet

I can tell you and there were a few sitting around Sunday at IRCHA watching, built the head, frame and complete tail all installed in 3.5 hours, now get busy.

[DominicD]

Took me 3.5 hours just to get the links on the rods

[R0t0R]

Took me 3.5 hours to figure out how to open the box! LOL OK...not really, but I'm not a speed builder. Got the head built and heading back down to the shop to do more before the girlfriend gets home and puts a stop to the build for the night.

[DominicD]

Tell her you cheated on her, then you will have the spare time to finish the build.

[R0t0R]

LOL! Well, I would, but even as sexy as the Velocity 90 is, the girlfriend still has better curves!

Just found a small difference in my FBL kit from the manual. On page 8 of the manual, it shows the arms on the upper part of the swash angling opposite of the swash arms on mine. (The arms that the links going to the blade grip arms attach to) Not a big deal, but if you put the ball links on the side of the arm depicted, the linkages won't be correct. Also, the 6 small screws in the top of the swash didn't look like they had any loctite on them, so it's worth taking them out and checking them. I'll attach a photo of my completed swash.

[Foxden]

Don,

I was just on the phone chatting with Charley and it shouldn't matter which side of the swash the balls are facing, I understand the Vel 90 FBL swash balls are reversed from the Vel 50, but they are the same distance from the center of the main shaft and in line so it shouldn't matter.

[R0t0R]

Thanks Clyde,

Yah, I just reversed them from the picture in the manual since the arms are angled reverse. You can see from my picture that if you put them on the other side of the arms as these are, the balls would not be spaced 90 degrees from each other around the swash.

[R0t0R]

Well, after getting a hard time from the Heli Godfather (Clyde) LOL about my heli not being built, I've got fewer little parts and a bigger big part.



I've been very impressed with the parts quality, packaging, etc.. Charley really hit a home run on this one!

A couple of hints I found along the way:

When I installed the elevator A-arm on the control rod, I left the 2 screws that hold the A-arm control rod slightly loose. That way they kept the screws on the flat spots, but could move slightly side to side. Then when I put it between the frames, I assembled the control bellcranks on each side and put the retaining screws in each end of the control rod. That centered up the control rod in the assembly and I was able to go back one at a time, loctite and tighten the screws in the A-arm assembly.

The other thing I did was something that we have been doing on the V50 for set screws on the elevator control rod. For ONE of the set screws of the elevator bellcrank (the one that goes on the flat spot) I ground the end down flat. That gives the set screw a little more surface area on the flat spot. The other set screw, I left the more pointed end on it so it bites into the rounded part of the control rod better. Not sure if this was really necessary on the V90, but it worked well on my V50, so why not. There is NO play in the control assembly with it together now. I did the same thing on the set screw that goes on the flat spot of the starter shaft/cup assembly.

One more hint. Not sure if anyone else has had this happen on their V50, but I was having the bolts that hold the gear struts on breaking. I believe it was from the temperture differences expanding the plastic of the gear struts. I now use red loctite on the bolts going through the gear struts into the mounting blocks and don't tighten the bolts as much. After doing this, I have not had another bolt snap, so I did the same thing on my V90.

Today is mounting the servos, building the tail and my least favorite part, making the rest of the control links! Not 100% sure if I will mount the SK720 sideways in the gyro mount position or on top of the servos on the "optional" plate. (Yes, it is included in the kit.)

Will post more as I get a little farther as well as posting my initial setting for the SK720 once I get it set up.

[Foxden]

Don,

When you start doing the servo's and wiring I would recommend removing the plastic radio tray as it will make it much easier to get the wires all neat and secure in behind then just re-install the radio tray and all your wiring will be neatly tucked away behind, just bring out what you need to plug into the RX, I mounted the battery on top, RX below, and the MutlyGov on the throttle side in the radio tray. Made for a very easy neat install with it removed.

[R0t0R]

Thanks Clyde! I'm working on that right now. Just came upstairs to do some initial programing on my SK720, then have to do a little soldering so I can get power to my power bus and set up servo centers, etc.. Right now, it looks like I will mount the SK720 sideways in the gyro cutout, power bus on the bottom (underside) of the radio tray, MultiGov Pro on the throttle side of the tray (just like you mentioned, got it in the same place on my V50) and battery on top of the tray.

Those links are a BEOTCH! Got all the links built. Had to do the Capinator's hint of putting the link rod in vise grips, but my ball link tool was too narrow for the beefy links. Wrapped them with a towel and LIGHTLY gripped them with some pliars and was able to turn them that way.

Heli is pretty much built and on to radio, linkage, accessory set up. This is the part that takes my slow butt a while, but hope to have it flying in time for the monthly Colorado Rotorheads meeting/get together and fly on Weds. evening.

Got a couple of more photos and hints that I will post later

[DominicD]

Yeah these RJX link tools don't actually fit, but some quick work with a file fixed that.

[R0t0R]

Have a couple more hints and pictures from the build.

I really like how the hardware for each part is included under that part in the foam. For things like the different frame bolts, so I didn't loose the ones for the left side, I put them loosely in the bearing blocks, frame spacers, etc.. Then when it came time to put the left side frame on, I took the screws out and laid them in a pattern of where they went on my workbench. Made it easy to get them in the right spots for guys like me with a short memory!

I left the servo mounting plates (the metal orange anodized ones) for the elevator servo off until I got the frames and bellcranks all built. I wanted to see if the elevator control rods would line up better with the servo mounted inside or outside the frames. Well just like Capi (probably since we both are putting 8717s on the cyclic!) it works better on the inside of the frames, so I put the mounting plates on the outside of the frames, again just like Capi.







You can get to the mounting screws asy enough inside the frames, but a ball end hex driver makes getting at them a little easier.

The last thing I noticed is VERY minor. The manual shows the little notches in the forward left servo mount plates as facing backwards. I believe they are supposed to go forward to give full range to the servo mount plate adjustment. Below is the picture of what I'm talking about. For most, it won't make a bit of difference, but if you use a small servo, you might not be able to move the mount plate back all the way. Also, there are 4 longer screws for this servo. I put one in on another servo before I realized they were for the one with the servo mount spacers.



All pretty minor things and Capi already did the one with the elevator servo mounting. Just wanted to include a couple more photos. Next will be my electronics installation and SK720 set up!

[R0t0R]

It's finally done! Had to go out of town unexpectedly for a couple of days, but was able to finish up today and hope to start breaking in the engine tomorrow.

I have the same "notchy" tail case gears that others have talked about, but Clyde mentioned that they should wear in after a flight or two so will give it a try.

Capi got all the good build tips, so I don't have much to add. One thing I did on my Velocity 50 and did on the 90 was replace the button head self-tapping screws for the rudder pushrod guides with 2x10mm cap head machine screws. Never had much luck with not stripping the button heads.



For mounting the SK720, it is a tight fit in the gyro cutout, but it did fit with enough room to clear everything when turned sideways. By twisting the satellite RX wires the opposite direction from how they came, I was able to get the wires on both to bend up, keeping them from contacting the back of the cutout. Lightly heating the wires with a heat gun and holding the twist while it cools, keeps the wires in the position I wanted.



You can also see in this and some of the other pictures that I put a small bead of low temperature hot glue along the servo connectors. It's just extra insurance that the connectors don't vibrate loose. The strip of hot glue will peel right off if you need to disconnect the wires.

It's best to leave the wires coming from the SK720 slack so as to not transmit vibrations to the unit. There are only 4 servo type wires and the 2 satellite RX wires coming from the unit when using the power bus. 2 of the servo type connectors are turned sideways as they only carry signal to the power bus.

In the photo below, you can see how I left the wires with slack in them for a distance from the SK720. Even though I sanded the edges of the CF frames, wherever wires cross an edge, I protected and padded it with the loops side of Velcro tape. The power bus is mounted under the radio tray with velcro and a velcro strap around it. My Perfect Regulators fail safe switch is mounted on the side with some of Charley's Rotorworkz gyro tape. The switch I have on my V50 was mounted with the tape the switch came with and it came loose very quickly. After mounting it with the Rotorworkz tape, it is still solid over 50 flights later.





On the left side of the radio tray, I mounted the MultiGov Pro, again protecting the wires with velcro where they come in contact with the frames. It is attached with servo tape with a velcro strap as a backup that also goes around the wires on the other side of the tray.



Ready to go fly tomorrow!





Doesn't look near as "boxy" anymore!



If anyone is interested, I will post my initial SK720 setup and any changes I make once I get the motor broken in and can really wring it out. All of my helis have the SK720 in them and setup is pretty straight forward.

[DominicD]

Rotor might wanna drill a hole in the back, those sat wires look like eventually they will fail.

[R0t0R]

I'll keep an eye on them, but did the same kind of thing on my V50 and they stayed right where I put them over a 150 flights later.

[dobje]

Rotor,

For getting the corect resolution on the FBL head what is the size of servo horns and the control arms in mm ?

Thanks.


Ps and the tail servo horn.