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AlignRC Thunder Power RC
THX1138

Elite Veteran

Camp Bondsteel, Kosovo

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So I've decided to have a serious go at FAI competition flying. After talking with the Hiatts and several weeks of online research, I've decided to build my first Goblin, the Urukay Competition.

My intention with this thread is just to document my experience with the build, set-up, and initial tuning of this machine.

All the SAB manuals are available online so I had already downloaded it and read through it a few times. It is well written and has very clear pics and diagrams of what goes where. The whole kit is packaged exceptionally well and I am super impressed. So far, no parts are damaged and all the bags are very clearly labeled what step they are for. A pleasant surprise was the embroidered towel included with the kit.

Since I no longer have a large workbench, the living room floor is where I am... The box marked, "box carbon Urukay CO", is now my build space. I'm using the towel to help keep small parts from rolling away... And it looks cool in the pics ;-)

And, here... We go! First thing is prepping the frame halves for the build. Very clean, high quality carbon is finished very well but does have some sharp edges. Page 4 shows exactly where to sand. Some 600 grit silicone carbide sand paper dressed the edges perfectly. Now time to turn some wrenches! The base plate/ battery mount is first up and goes together as advertised. One thing I noticed that's worth mentioning is the hardware. It's been a long time since I've used some high quality metric screws and not the cheaply made Chinese stuff.

Moving on to the frame halves... One thing I'll note here is that the manual doesn't have a whole lot of text. For the most part this isn't a big deal. I think it is also assumed that if you are building this kit, you've been in the hobby for a minute and have a little experience.

So far, the fit and finish is spot on. One thing I like to do is leave all the hardware loose until I actually join the halves together. By doing this, it's easier to ensure the frames are square out of the gate.

The landing gear is one piece composite. It is pretty strong and surprisingly light. When you tighten up the frame half hardware, leave the landing gear supports(H0496-S) loose. Bolt the landing gear on and snug it up without getting to carried away or you may crack the strut. Once the gear is on and tight, go back and tighten the 4 screws that hold the landing gear supports to the frames. Again, this helps keep everything nice and square.

The last step in the initial frame build up is the ESC mount. Although the manual doesn't mention it, I hit the upper edges of the ESC mount with the 600 grit. So far I'm very impressed and I can't wait to build more :-) It's time for me to call it a night.

Lou

Just give me five dudes and two flashbangs...

08-06-2016 08:24 AM
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CHiatt

Senior Heliman

Winter Garden, FL

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Good choice Lou!

Lou,
Good luck on the build! Drop me a line if you have any ?s.

Cliff

08-06-2016 11:19 AM
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THX1138

Elite Veteran

Camp Bondsteel, Kosovo

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Thanks Cliff, will do!

This morning I moved on to the main transmission build up. The manual is pretty clear on how it goes together and I had no issues. I am extremely impressed with the machine work, it is very clean and accurate. Fit and finish are flawless.

The main and secondary shafts have a thin coat of packing oil on them, make sure to clean this off as it will only attract dirt later. The tail drive pulley and main gear assembly are assembled at the factory. I did remove the screws to check for loctite. The tail pulley had none but the main gear did. I applied loctite where needed and tightened everything down.

When you install the main shaft, check for free movement through the bearings. It should fall right through under its own weight. If it doesn't, one of the bearings is crooked and you'll need to seat it.
As I was looking at the manual, I saw there are no shims in the main mast stack up. The mast has a machined ring the rides on the top bearing. After you install the main gear, you install the locking collar. The lowest hole drilled in the mast is slightly oversized and this is where you take up the vertical slack in the main shaft. Press down on the mast while pushing up on the collar then tighten the screw. This is a simple design and it works very well.

The last step is installing the secondary shaft. This is actually the primary drive from the motor and also the tail belt drive pulley. The drive pinion only bolts on one way. The one way slides up and sits clean below the main structure. Pay attention to the shim stack. I used all 4 of the shims and it still has a little play but nothing I'm too concerned about. The last step is installing the belt tensioner assembly. This was strait forward and goes right together. This completes the main transmission assembly.

Next up is the motor mount...

Lou

Just give me five dudes and two flashbangs...

08-06-2016 03:57 PM
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CHiatt

Senior Heliman

Winter Garden, FL

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Do this mod to be able to remove the main gear easier...

File flats on the bottoms of the two spacers on the right side so the main gear can be removed without binding. You just remove a little where the spacers flare out to seat in the bottom plate.

C

08-07-2016 12:35 AM
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THX1138

Elite Veteran

Camp Bondsteel, Kosovo

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Thanks for the tip on the main gear :-)

Moving on with the build, I soldered up the bullets on the Xnova 4530-500. This motor may be a little overkill but we'll see how it goes. The motor mount is pretty strait forward and there is really nothing to say about it.

One thing I did change is the pinion. Using Mr. Mel's head speed calculator, 20t pinion will get me 1800 in idle up. The kit includes a 20t but it is bored for an 8mm motor shaft. Also included is a brass sleeve so you can use a 6mm shaft. The bearing support is designed around a 6mm shaft as well. Personally, I don't like the sleeve... A little research and "comparative maintenance" found a 20t that is made for a 6mm shaft and has the same dimensions as the kit included pinion. The tag in the pic has the P/N for the 6mm bored pinions if anyone wants one.

Lou

Just give me five dudes and two flashbangs...

08-07-2016 08:11 PM
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THX1138

Elite Veteran

Camp Bondsteel, Kosovo

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Now for my favorite part of any heli build, the rotor head. After all, it really is the heart of the machine.

Talking to Cliff Hiatt at nationals, this is one of the mods he recommended when building the head. The head from the factory has a very square edge in the damper housing. I used a dremel with a fine grit, beveled stone and just "kissed" the inside lip of each hub arm. This puts the slightest chamfer in the damper housing and makes the dampers much easier to install. It is very difficult to see in the pics but the left pic is factory and the right is after the mod. Use low rpm's and be very patient if you decide to do this.

Next we install the individual feathering shafts.

Next up are the dampers. I am using the factory recommended damping of one hard inside, soft outside. After that the head shims are installed. The pic shows the recommended factory set up of one 1mm shim and one .2mm shim. Once all three blade grips were installed, the pitch arms drooped under their own weight. As a result I did add the additional .2mm shim to get the preload as prescribed in the manual.

The thrust bearings a huge and very high quality. The whole bearing stack and blade grip is held on by the massive M5 spindle bolt.

I use Tri-Flow synthetic grease for all the head internals and the finished head is simply gorgeous. The swash driver is all ball raced and fits very nicely to the bottom of the head block. The swash itself is exceptionally smooth and appears to be rebuildable if needs be.

Next, we start to hang some avionics...

Lou

Just give me five dudes and two flashbangs...

08-08-2016 12:40 AM
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THX1138

Elite Veteran

Camp Bondsteel, Kosovo

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Got a lot done today :-)

First thing was the cyclic servos. The kit provides two sizes of screw to use when installing the cyclic servos, three M2.5x12 and one M2.5x8. The DS-8717's are just thick enough at the mounting tab. I found three Philips head M2.5x12's in some misc. hardware I keep. Solely for aesthetics I installed these in lower mast bearing block so they are not as noticeable.

*side note - I've had these servos for a while and this is the third heli they've been in. The grommets were chewed to death and the brass spacer sleeves were trashed too. It was an amazing PITA to find new ones...*

Next, the tail rotor servo is installed.

Once the tail servo was installed it was time to mount the motor. The tension springs installed in the motor mount itself do a very good job keeping the primary belt under tension while you tighten up the screws.

This next step gave me quite the surprise... I'm currently using a V-bar Blueline but will eventually switch to a Neo. I connected it to my laptop earlier for centering the servos. I built up each of the swash links. All three ended up right at 64.5mm. I connected the swash and it was dead level right out of the gate! I am more impressed with this machine every step I build!

Lou

Just give me five dudes and two flashbangs...

08-08-2016 10:26 PM
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THX1138

Elite Veteran

Camp Bondsteel, Kosovo

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Moving on... The assembly of the tail rotor is actually the next step but I skipped this and went to build up the tail boom.

Starting with the tail gear box, the tail build is very different from every other heli I've built. As I said earlier, this is my first goblin. One of the unique design features is the fact the boom is one piece and its own independent structure. The tail gear box is not much different from other belt driven tail rotors.

Prepping the front of the boom is easy but the rear where the gear box mounts is a little bit of a chore. The rear has two plates with lock nuts glues in them. I got carried away with the build and I didn't take a pic of them, sorry for that. The kit includes two double sticky foam pads. When you affix the pad to the plate, there is a lot of material that is open to the elements. I trimmed mine as close to the plates as I could to keep dirt and debris from sticking to it on the inside of the boom. I used the 4 gear box mounting screws as "guides" to get the plates lined up on the inside of the boom. Once on, a little pressure sets them firm and they are in position for when you attach the tail gear box.

When you do mount the gear box snug the screws but leave them loose...

Lou

Just give me five dudes and two flashbangs...

08-09-2016 01:42 AM
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Jabber

Heliman

Hong Kong

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I see you are using servo grommets when they are excluded from the build plan. It appears this is a deliberate omission, wondered why you put them in? I have no idea either way, just interested in your thoughts.

08-09-2016 02:05 PM
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THX1138

Elite Veteran

Camp Bondsteel, Kosovo

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Hmm... I didn't even think about that. I've just always used them. I'll have to look at the manual again when I get home from work. Thanks for pointing that out.

Lou

Just give me five dudes and two flashbangs...

08-09-2016 02:09 PM
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THX1138

Elite Veteran

Camp Bondsteel, Kosovo

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After looking at the manual again, I can see why you would question the use of the servo grommets. In my opinion, the manual is exceptional. I feel that if the grommets were not to be used it would have been called for specifically in a text block as other specific instructions have been presented in other steps of the build.
After taking a better look at my model, center of the servo ball and center of the swash ball is maybe 1mm off... maybe... If I were to remove the grommets, this would turn into a 3-4mm difference. The DS-8717's I'm using are firm and there is no play in the mounting. I think I'll be ok, if anything, I may try to "shim" the servos outward to achieve true alignment of the swash drive links. I'll fly it first and see if I notice any unwanted flight tendancies. If so, then I'll start looking at possible adjustments to the servos.

Lou

Just give me five dudes and two flashbangs...

08-10-2016 02:12 AM
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Jabber

Heliman

Hong Kong

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This has been the subject of discussion before, I think, but not sure of the source. Will take a look. The kit does include alternative balls with stand off to assist in getting a good line on the swashplate, this also helps. Dhiatt might be able to shed some light on this?

08-10-2016 04:29 AM
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GyroFreak

rrProfessor

Orlando Florida ...28.49N 81.22W

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Thanks for posting all the build pictures. That looks like an incredible machine, beautiful machine work on all the aluminum frame and head assy.
Been out of the heli stuff for awhile, last build was a M.A. Razor, which I stretched to 700 size.
Paul

I think about the hereafter. I go somewhere to get something, then wonder what I'm here after ?

08-10-2016 03:56 PM
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THX1138

Elite Veteran

Camp Bondsteel, Kosovo

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Thanks for the compliments brother! I'm getting pretty close to being done and I should be able to post more pics later tonight.

Lou

Just give me five dudes and two flashbangs...

08-10-2016 07:18 PM
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THX1138

Elite Veteran

Camp Bondsteel, Kosovo

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I am making a lot of progress with the build, I'm probably at 95% complete. I have a few more pics to add and I'll get to it soon... Stay tuned!

Lou

Just give me five dudes and two flashbangs...

08-11-2016 01:01 PM
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THX1138

Elite Veteran

Camp Bondsteel, Kosovo

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Jabber

Upon further review, I have decided to stay with the servo grommets. I don't feel they are hurting anything and the mount is solid.

I did however remove the stand off ring from under the ball. This configuration gives an almost perfect alignment of the swash drive link.

Lou

Just give me five dudes and two flashbangs...

08-11-2016 07:04 PM
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THX1138

Elite Veteran

Camp Bondsteel, Kosovo

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Moving on with the build, next thing up was hanging the boom. Since I am new to the Goblin world, the boom mount comes as a bit of a shock...

Once installed, it all made perfect sense. I do appreciate the tool included for tightening the nylon bolts. I also feel much better seeing the safety lock installed to keep the nylon bolts from backing out.

Lou

Just give me five dudes and two flashbangs...

08-11-2016 07:10 PM
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THX1138

Elite Veteran

Camp Bondsteel, Kosovo

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The tail rotor assembly is quite impressive. The hub and axles are actually one machined piece. Place the wave washer on the axle, then the blade grips slip on. Next, install the bearing stack and finish with setting the axle screw. Too easy.

The brass pitch change links were quite a surprise. After talking with Cliff at Nats, he informed me that the prototype was very tight tolerance and required some work to get smooth. These bolted together with no issues and are the smoothest pitch change mechanism I've ever seen. There is a minimal amount of play "up and down" on the mounting hardware but are slop free in the direction of travel.

So... balancing the tail has been a night mare. I have gotten it pretty close but it is not perfect. I am open to any suggestions at this point...

If I understand correctly, a 3 blade tail(prop) is balanced when all three blades will individually sit parallel to the ground. I can get any two, but not all three. I have spent no less than 5 hours on this. At this point, I have decided to go ahead and install it on the aircraft. I intend to use the vibe analysis on the Vcontrol to see what the actual level is...

With the tail hung, I installed the tail push rod and tail servo horn. I absolutely love the tail push rod guide! The manual calls for CA to glue in the rod ends. I've never had luck with this in the past so I opted for Double Bubble 5 min epoxy. I fixed both ends to the length prescribed in the manual and let it sit over night just to make sure it was cured well. The ball ends screwed right on and the guide actually allows the rod to pass through assembled. Once the rod is in position, a keeper is screwed into place and takes up the slop in the guide. I have also included a shot of the tail set up screen to show my settings.

We are getting closer!!

Lou

Just give me five dudes and two flashbangs...

08-11-2016 07:40 PM
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THX1138

Elite Veteran

Camp Bondsteel, Kosovo

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Mounted the ESC this evening. I'm using the YGE 160 Xxtreme edition and it fits very neatly atop the ESC mount. I used some stainless M3x30 screws and they hold it down very well. I then used waxed line to tidy up the wires and run them aft to the Vbar control amp.

If you guys don't have wax line, I highly urge you to get some. It holds up pretty good over time, it saves your wires from chafing due to vibration, and it looks kind of cool to ;-)

Lou

Just give me five dudes and two flashbangs...

08-12-2016 04:03 AM
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THX1138

Elite Veteran

Camp Bondsteel, Kosovo

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Super busy weekend with the family. I did t ha e much to time work on the rig. I've been trying to learn the Vcontrol and that is coming along. I've also just acquired a Vbar Neo w/ Vlink... So I'll pretty much be starting the programming all over again. It shouldn't take to long as I'm pretty happy with the mechanical side of things. Hopefully, later this week should be the maiden.

Lou

Just give me five dudes and two flashbangs...

08-15-2016 03:14 AM
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