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Jun 04, 2015, 04:44 PM
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Build Log

CN Models Optimus EL (F5J)


Long story short I was looking for a contest glider. I've been building like crazy for the past year or so and was looking for a current, modern, competitive 5J model. To be honest I was going to order a Maxa Pro EL. It had all the check marks but then came this thing!!!

Just to give some props to a vendor, Ali at Flighcomp.com who is selling the Optimus here in the US hooked me up. I had been buying parts from him to fix a lot of my older models and found him as a great vendor, I would highly recommend his company. He sells more focused products and I also find his website has more value items than other vendors that sort of sell everything.

For those that are curious here is the mfg website:
http://cn-models.com/?page_id=316

Here is the Intro thread here:
https://www.rcgroups.com/forums/show...j#post29975340

Here is the 3J thread:
https://www.rcgroups.com/forums/show...hlight=optimus

Here is the youtube video:
CN-Models Optimus F3J and F5J Sailplane (18 min 54 sec)
Last edited by Bmwjoon; Jun 04, 2015 at 04:52 PM.
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Jun 04, 2015, 04:47 PM
Registered User

Raw Weights


Pod - 134 Grams
Pod cover - 5
Center Panel - 528
Left - 217
Right - 214
Joiners L+R - 41
Rudder - 11
Elevator - 36
Boom (includes 2 preinstalled pushrods) - 92

It's light. I would have to assume it's lighter than the 3J version. Also the pod is different than the 3J version. Notably the ballast tubes are installed in the center panel. I haven't gotten started yet so the next post I'll try and show pictures of the parts.
Jun 05, 2015, 02:29 PM
Registered User

Pod and Boom


The pod is quite Maxa-ish. It comes uncut for the motor and obviously comes out of the 3J mold. Again no ballast tube. The wing mounting area comes pre-routed for access as compared to the 3J model that has the mount for the other end of the DB9. The layup is pretty high quality compared to some of my other models. The inside is aramid and toward the wing mounting area it's darker so I would have to assume there is carbon in the back half of the pod. That's evident on the edge that is routed near the wing mounting area. The hatch is again "vladish" and pop's in and out of a routed opening.

The boom is tow and the rudder is spread tow. It's pretty light as it is still compressible if you squeeze it. The rudder is pre-mounted with what looks like CA. Again very vlad like. Quality of the spread tow is pretty tremendous on this piece. The pushrod for the rudder and the rod and bell crank for the elevator are all pre-installed so no work there. The rudder control surface is somekind of a carbon tow rod and balsa covered in what looks like oracover. It is held on by a small metal pin and a small alloy screw.
Jun 10, 2015, 06:01 AM
Registered User

Wing tip and horizontal


The quality of the wing layup is very high. The finish is almost perfect and the spread tow looks awesome. Of note the wings have some additional pieces of spread tow cut in a different pattern to add reinforcement or vary the twisting properties of the panel. The wipers are painted a different color. Not sure if I have seen that before. The control horn comes preinstalled. The servo mounting area is reinforced with some additional carbon and comes pre-sanded. They also add balsa spars to box off the servo mounting area. I wish they moved the balsa out maybe 3-4 mm wider as it is difficult to use servo trays with bearing support. Barely fit with some modification to the tray.

The horizontal stab is covered carbon d-box and balsa. It feels extremely light. The only thing I can note is it's enormous. It looks oversized. I assume they wanted some pitch authority with this model I don't mind the built up surfaces as they are very high quality and extremely light. I think I would have preferred molded parts.

I was lucky enough to find some time and started installing wing servos. I'm still waiting for some parts. Maybe I'll finish sooner than later.
Jun 10, 2015, 06:28 AM
Registered User

Part Selection


Reisenauer 5:1 micro edition gearbox
Turnigy 3600kv Rotorstar
Castle Creations 50A Edgelite
Hyperion 900 HV
Frsky X8R with the cover removed and non-pcb antennas
Scorpion backup guard
MKS HV6100 for ailerons
MKS HV6100 in the fuse
JR HV398 for flaps
RC Solutions servo trays

Originally I was going to use a Schambeck 1025 but I wanted something that was cheaper to fix and change. I figured if I used my own gearbox and wanted to tweak my setup it would be a easier. I picked this HK motor because it had a high wattage rating and it was cheap. Honestly I have no idea if I picked the right motor I just plugged some numbers into ecalc and bought a few different props. I'm going to try 16x6, 16x8, 16x8.5s, or 16x10.

I want to setup the model for a small battery. I decided to use these new hyperion 4.35v packs. I don't know if they are any good but they were 13 bucks each. Also my next order from HK i'll probably buy at least one 850mah just to compare performance. I have some 1300s i'll probably use when i'm flying for fun. I'm going to use the ESC BEC with a Scorpion backup.

Servos are all HV. I've never used MKS6100 before but the hump next to the horn is annoying and I don't like having to setup the servo around it's goofy shape.
Jun 10, 2015, 03:04 PM
Registered User

Center Panel and accessories


I think the unique feature of the 5J version is the pair of ballast tubes installed into the center panel of the wing. The ballast is strung on a small rope enabling it to be snaked inside the tubes built into the center panel. Pretty trick. Unfortunately I'm not sure how fast you can cycle through installation in case the wind suddenly dies/picks up on you. You figure 2 bolts for the wing and 2 screws for the ballast. Maybe with practice 3-4 minutes is realistic.

Again the laminate work is very good. Wiring harness and DB connector come pre-installed. My model came with white paint in the center. Not sure if all models come this way. The wing also has a molded recess to align the pod. The fit is quite perfect so any torque created by the wing on the pod is held by this and not as a shear load on screws or bolts, again pretty trick.

The accessories are pretty ordinary. Comes with a thick fiberglass motor mount about 29mm in diameter. 2mm threaded pushrods and clevises. The only thing I upgraded was the rudder horn. I ended up just making one out of some 2mm carbon to cover some of the balsa on the bottom. I'm not sure they paid too much attention to this. Also come with a small piece of plywood for servo mounts which I probably wont use and the DB9 with servo wires already setup. Again a big time saver.
Jun 10, 2015, 03:13 PM
ak79's Avatar
Looking good! I'm glad to see you started working on her!

How much does that HK motor/Reisenauer Gear Box combo weigh?
Jun 11, 2015, 05:26 AM
Registered User
I'm still waiting for the gearbox to weigh it myself but the combo is supposed to weigh 110 grams. I had servos so I decided to just start installing them. Just 1 more flap servo to go ! I was going to wait for the motor/gearbox/spinner to start on the fuse servos but I'm pretty sure I'm going to put both under the wing.
Jun 11, 2015, 01:30 PM
Registered User

RC Solutions Servo Tray


Finished the last wing servo. I used RC Solutions bearing support trays from Flightcomp.com. They are well designed and they actually do fit perfectly. I never used trays with bearing support before but just testing the servos on the bench you can see the arm is much more sturdy in rotation around it's axis. Just make sure you have room I have 1 servo off maybe 1mm from it's optimal position but that actually doesn't bother me. Well, maybe a little bit
Jun 11, 2015, 01:38 PM
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Rudder Control Horn Mod


I didn't like the stock horn so I made this out of some 2mm carbon. Also used a sharpie to black out some of the balsa and aluminum. The threaded hole is for the screw that holds the rudder in place.
Jun 11, 2015, 06:32 PM
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Luis Moya's Avatar
What is the airfoil on this bird?

Thanks

Luis
Jun 12, 2015, 08:33 AM
Registered User
Quote:
Originally Posted by Luis Moya
What is the airfoil on this bird?

Thanks

Luis
Actually Luis I'm not sure. I would assume its proprietary but for those guru's I'll try and post a picture here later of the profile.
Jun 12, 2015, 01:55 PM
Registered User

Fuse servo tray


CN gives you a little piece of plywood. Perfectly fine and large enough to lay 2 servos side by side at about a 30 degree angle. If you look at their website picture that is how they show the servos installed. Like I said before 6100's have a bump that would interfere with this method so I decided to line them in a row. Fortunately the threaded insert for the wing bolt allows you to put a small screw driver through it so I was able to mount the forward servo pretty far forward. This is important so you can slide your receiver into the back of the pod. Pretty easy as the hole the routed for access is pretty big. In general the pod size is extremely generous with the 3J ballast tube removed. You could easily fit an enormous battery or mount the fuse servos forward.
Jun 13, 2015, 12:12 PM
Registered User
Yes I`ve mounted my DS1600s in line under the wing seat but I`m putting my receiver up front under the canopy as I prefer to extend the wiring harness cables rather than poke the receiver aerials outside the fuselage.

Eddy. UK.
Jun 15, 2015, 03:28 PM
Registered User
Quote:
Originally Posted by Eddy Small
Yes I`ve mounted my DS1600s in line under the wing seat but I`m putting my receiver up front under the canopy as I prefer to extend the wiring harness cables rather than poke the receiver aerials outside the fuselage.

Eddy. UK.
There is so much room in the front of the pod I was also tempted to stick my receiver up front. Did you already mount the boom to the pod? I'm in the process of doing that now. I made a nice jig out of foam poster board. I'm almost finished. I'm going to post pictures of it once I finish setting it up.


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