Detailed Protos build (warning: contains a lot of large pictures)

[kjoer]

Well, considered for months getting a Protos, I received all my components, I ended up with this setup:

• MSH51106 Kit Carb - kit ONLY
• MSH51321 Stretch kit Protos 500 - CARBON ONLY -
• MSH51115 Flybarless upgrade Kit
• MSH51335 Low flybarless hub (only stretched protos)
• MSH51122 Alu pulleys set
• MSH51135 Tail blades Orange
• MSH51063 MSH Scorpion HK-3026 880KV
• YGE 80 with built-in external governor support
• Mikado 04357 Mini V-Bar "Blueline" 5.3 Express
• Mikado 06003 VBar Software 5.3 PRO
• 3x MKS DS9660A+ mini size swash servo
• Futaba BLS251 brushless standard size tail servo
• Futaba R6303SB 2.4GHz FASST Micro S.Bus HV Receiver
• EC3 connectors

Unfortunately I wasn't able to get a FBL kit, though I've seen one store which supposedly has them. However, I did manage to find an unused original YGE 80, which is out of production these days. I had it sent in to YGE, to include external governor support. I've also ordered a single Desire Power 6S1P 3000mAh LiPo and will start from there. I've replaced the stock motor shaft already with the long one from the stretch kit, using a self made tool, an arbor press and a drill press. Here's a pic with all the components:



full resolution pic: http://rzavelli.home.xs4all.nl/stuff...s/IMG_2061.JPG

Time to go building!

[kjoer]

Wet sanding of the carbon fibre plate parts:



full resolution pic: http://rzavelli.home.xs4all.nl/stuff...s/IMG_2067.JPG

I'm sanding some extra Protos and Mini Protos tail fins, since I seem to molest those on a weekly basis, doing retarded but funny auto's.

[kjoer]

Before continuing I've decided to clean my work bench first, placing my wrenching towel again (to prevent the bouncing of screws off the table). Table isn't planar, was growing pretty tired of screw drivers rolling off from it.



full resolution pic: http://rzavelli.home.xs4all.nl/stuff...s/IMG_2073.JPG

Now it's time to center servos and prepare servo horns.

[solex227]

Looks like a great start to a build thread ! look forward to seeing more!

Solex227

[Dr. M]

Looks like a top-notch setup. Very nice!

Why are you sanding the CF plates?

[kavic5150]

Originally Posted by Dr. M

Looks like a top-notch setup. Very nice!

Why are you sanding the CF plates?

Wondering the same thing myself.

[solex227]

Originally Posted by Dr. M

Looks like a top-notch setup. Very nice!

Why are you sanding the CF plates?

Originally Posted by kavic5150

Wondering the same thing myself.

Might be a Static measure.... or he might want to paint the part lets see.

Solex227

[prillernut]

Originally Posted by kjoer

Well, considered for months getting a Protos, I received all my components, I ended up with this setup:

• MSH51106 Kit Carb - kit ONLY
• MSH51321 Stretch kit Protos 500 - CARBON ONLY -
• MSH51115 Flybarless upgrade Kit
• MSH51335 Low flybarless hub (only stretched protos)
• MSH51122 Alu pulleys set
• MSH51135 Tail blades Orange
• MSH51063 MSH Scorpion HK-3026 880KV
• YGE80 with built-in external governor support
• Mikado 04357 Mini V-Bar "Blueline" 5.3 Express
• Mikado 06003 VBar Software 5.3 PRO
• 3x MKS DS9660A+ mini size swash servo
• Futaba BLS251 brushless standard size tail servo
• Futaba R6303SB 2.4GHz FASST Micro S.Bus HV Receiver
• EC3 connectors

looks like an excellent setup, have fun!

[kjoer]

I'm not sanding the planar surfaces. Wet sanding is done just to smooth the edges, feels nicer to the touch and looks better.


It's an old habit from competitive RC car racing, there we would go even further with CF parts to seal them, preventing splitting:

- Wet sand across the CF edges with 600 grit sand paper whilst holding in a small vice, this would round the edges.
- Degrease the parts thoroughly with soapy water.This is important, since CA drying up near greasy areas will leave dirty white stains.
- Apply thin CA to a cotton swab (Q-tip) and drag that around the edges to seal them.
- Softly wet send the CA in the length of the edge with 1200 grit sand paper in a small vice to get an even semi-gloss finish.

But anyway, for helicopters I just do the first step, no point in sealing.

If you want to sand your CF part edges as well, make sure to use water, since the fibers in the CF dust are nasty. Once nested in your lungs, they stay there, forever. Hence sanding with water.

[rossk]

I didn't know about sanding the CF edges until I built the Diabolo, manual has it as an optional step 1.
From now on I think I will do it on all my heli frame sides.
Takes away the sharp edges, so less chafe points, feels nicer and looks better etc.

Looks like a good build, I would go EC5's tho...

[prillernut]

Originally Posted by rossk

I didn't know about sanding the CF edges until I built the Diabolo, manual has it as an optional step 1.
From now on I think I will do it on all my heli frame sides.
Takes away the sharp edges, so less chafe points, feels nicer and looks better etc.

Looks like a good build, I would go EC5's tho...

Yeah, I debated on connectors but decided on EC5s myself. I've got 45A APPs and considered XT60s, but figured in commonality for my charger connectors and potential future use of the battery packs in a larger heli.

[kjoer]

Found the actual holes in the servo horns were of 1.5mm diameter instead of 2mm a few days ago (assumption is the mother of all **** ups). So during lunch break at work, I went to the shop floor. Bolted the servo horns inverted to a plank with a M3 screw and a fender washer, used a 2mm drill bit and drill press with high rpm to enlarge the existing holes.

16.5mm offset for the swash (16mm requested in the manual)
13.5mm offset for the tail (13.5mm requested in the manual)

Result:



full resolution pic: http://rzavelli.home.xs4all.nl/stuff...s/IMG_2077.JPG


Then the awefull job of trimming excess material, of course the end result has to look neat:



full resolution pic: http://rzavelli.home.xs4all.nl/stuff...s/IMG_2089.JPG


Swash servo horns fitted and trimmed perpendicular to the servo housing in the V-Bar software:



full resolution pic: http://rzavelli.home.xs4all.nl/stuff...s/IMG_2090.JPG


Now we finally get to the fun part, actual wrenching!

[kjoer]

It's always a wise idea to degrease any critical metal threaded part of course (including bolts), prior thread locking. The servo horn ball studs in particular, since they are packed with the main shaft bearing. I usually use brake cleaner for degreasing.

[kjoer]

Main shaft blocks with servos attached. Screws aren't tightened yet, which obviously allows me to properly align the blocks with the frame plates and main shaft later.



full resolution pic: http://rzavelli.home.xs4all.nl/stuff...s/IMG_2097.JPG


It wouldn't be Italian if it didn't have some tolerance issues ;).

CF frame thickness may be a bit on the upper tolerance end, since I had trouble inserting it in the moulded bottom plate without actually bending the frame plate. It was a tight fit with the Mini Protos, but for the Protos here it doesn't fit for me. Before pic:



full resolution pic: http://rzavelli.home.xs4all.nl/stuff...s/IMG_2112.JPG

I've used a small file to remove material on the inside of the arch on the moulded bottom plate, which relieved most of the stress.


Half a frame assy, did not use thread lock here yet. Screws are still mostly loose, since I haven't inserted the main shaft yet:



full resolution pic: http://rzavelli.home.xs4all.nl/stuff...s/IMG_2115.JPG




full resolution pic: http://rzavelli.home.xs4all.nl/stuff...s/IMG_2120.JPG


Now, the newer Mini Protos has a slot in the frame to run the front swash servo wire cleanly down the inside of the frame. The Protos does not. At this point I'm considering removing the frame plate and milling a small slot in the Protos frame plate.



full resolution pic: http://rzavelli.home.xs4all.nl/stuff...s/IMG_2130.JPG

[kjoer]

To run the front swash wire down the inside of the frame, I opted to file a slot from the side, rather than making a rectangular slot. So, took the plate off, used a wet file and made a slot large enough for the connector to slide through. Then I blended the edges around the slot on both sides of the plate, to prevent wire chafing.



full resolution pic: http://rzavelli.home.xs4all.nl/stuff...s/IMG_2135.JPG


Filed the arches on the inside of the moulded bottom plate some more, since the fit wasn't ok yet:



full resolution pic: http://rzavelli.home.xs4all.nl/stuff...s/IMG_2145.JPG


Slightly over constrained still, but it will have to do:



full resolution pic: http://rzavelli.home.xs4all.nl/stuff...s/IMG_2150.JPG


Please don't look too long at the CF plate quality and thickness difference between the left and right plates, a big no-no for RC car racers, but it will have to do here:



full resolution pic: http://rzavelli.home.xs4all.nl/stuff...s/IMG_2157.JPG


My small mod allowing the front swash servo wire to run to the back down the inside of the frame:



full resolution pic: http://rzavelli.home.xs4all.nl/stuff...s/IMG_2158.JPG


On the inside, it looks like this:



full resolution pic: http://rzavelli.home.xs4all.nl/stuff...s/IMG_2163.JPG



Assembled the frames loosely, inserted the mainshaft, slowly cross tightening all bolts going round a few times, only to notice the coaxial alignment of the three main shaft bearings was way off. Most likely due to tolerance stackup.

At first I experimented with shims a bit, then took the bottom bearing block out and filed down one of its sides until the three bearings were coaxially aligned with tightened frame bolts. It isn't that bad if the alignment isn't 100%, i.e. the shaft not falling down from its own weight. The side effect of that scenario, is that it stops the main shaft from spinning inside the ball bearing's inner rings. Anyway, this is how I ended up (after a lot of work):




Applied thread lock to the frame bolts, one by one, leaving the frame assembled. Afterwards I fixated the twelve servo bolts. I didn't thread lock the bottom plate bolts yet, since for installing the motor and ESC, it's easier to have that part removed. At this point the manual directs you to install the landing gear, which I won't do yet, since I find it easier to wrench on the thing without.



full resolution pic: http://rzavelli.home.xs4all.nl/stuff...s/IMG_2171.JPG

[kjoer]

The canopy mount M2.5x12 metric set screws come with a 1.3mm hex, as per the norm. A .050" (1.27mm) imperial hex screw driver fits perfectly here. When bottomed out, the screws weren't sticking out far enough for my taste, so I unscrewed them, leaving 4mm sticking out, then left the thread lock to cure overnight. Then screwed the canopy posts on today.

Sprayed the belt with silicone spray before heading to the office yesterday morning, only to find it still wet this morning. Oops, overdid it a bit. Wiped it a bit. (On my Mini Protos, I tend to spray a belt once before installing it, then leave it like that until it is replaced.) Installed the belt, main shaft and main pulley.

Ok, now the most confusing bit of this helicopter. It is delivered as a flybarred machine. However, there are not one, but two FBL upgrades.



full resolution pic: http://rzavelli.home.xs4all.nl/stuff...s/IMG_2185.JPG

You need the long ball studs from the first upgrade on the swash. I degreased all ball studs and the thread holes with brake cleaner prior thread locking them.

MSH51115 Flybarless upgrade Kit

Comes with long ball studs for the swash, long ball studs for the main blade grips and a different length feathering shaft.
Also has pitch links, swash drivers and a swash driver mount which is used with the conventional flybarred hub (the one with the hole in it).

There used to be a manual for this upgrade available for download on the MSHeli site, it isn't anymore. I still have it in my RC heli archive from downloading it a year ago, however its contents do not match the contents in the bag. Uhuh.

MSH51335 Low flybarless hub (only stretched protos)

The second upgrade, contains a low FBL hub, shorter pitch links and swash drivers which are mounted directly onto the hub. You need some of the parts from the first upgrade, to be able to use this upgrade. The reason why the low hub may only be used on a stretched Protos, is because when used on a non-stretched kit, your main blades supposedly may start a war with your tail blades. In other words, the boom wouldn't be long enough.

So basically, I'm looking at a flybarred Protos manual, a non up to date FBL appendix, parts from the kit and two upgrade bags, to build a low FBL head. Also, at times, one is looking at the manual for the stretch kit conversion.

Uhuh.

I hate assembling pitch links. This is the method I use for the servo to swash links, no link pliers involved:

• Rods are 42.5mm
• According the manual, base reference distance required between the plastic joints is 28mm
• Joints have to be screwed on 7.25mm per side (42.5-28)/2=7.25
• I clamp a rod in the vice
• Roughly screw just one joint on by hand
• Target a 35.25 remaining length of the rod 42.5-7.25=35.25
• Clamp the rod with the other end facing up and screw on the remaining joint
• Measure the in between length, fine adjust to 28mm

You can also eyeball it, I prefer the above.


Swash installed:





full resolution pic: http://rzavelli.home.xs4all.nl/stuff...s/IMG_2199.JPG

Now we can go and level the swash. I prefer the redneck method with a tiewrap. The benefit of this is that it's also possible to level the swash with a fully assembled head.



full resolution pic: http://rzavelli.home.xs4all.nl/stuff...s/IMG_2207.JPG

I numbered the servos with a marker earlier, which comes to good use now when trimming in the V-Bar software. I'm just looking for an equally spaced gap between the tie wrap and the plastic joints on all three points. Provided the servo horns were properly perpendicular aligned earlier and everything was built right, one barely has to adjust anything here. I needed just two clicks on one of the servos to level the swash.

The pro version of the V-Bar software allows you to level the swash as well at full negative and positive pitch positions, eliminating any possible interaction caused by different servo orientations, servo horn ball stud axial and radial variations.

Full negative pitch, only had to adjust one click:



full resolution pic: http://rzavelli.home.xs4all.nl/stuff...s/IMG_2215.JPG


Full positive pitch, only had to adjust one click here as well:



full resolution pic: http://rzavelli.home.xs4all.nl/stuff...s/IMG_2217.JPG


There are full negative/positive and cyclic stick combinations possible where the links ever so slightly touch the frame. I could prevent this using cyclic ring in the V-Bar software, but I'm gonna be lazy for now and assume my collective management skills are good enough to prevent this from happening in flight at this point. Can always readjust this later :).

[kjoer]

I'm gonna spare you all with pics of the assembling of the head, finding the required parts with the absence of up to date documentation was challenging, to say the least. The feathering shaft setup is fairly conventional, typical radial and thrust bearings positioning. Also, the shim to pass the axial forces down the inner ring of the outer ball bearing. I used some Associated silicone diff grease on the dampeners. I've ran the Mini Protos with and without grease, didn't notice a difference in flying or wear. Used Associated black grease on the thrust bearings. Unfortunately there are no shims included in this design to set dampening preload, something often used to compensate for tolerance stackup variations. The dampening feels pretty nice and tight as it is now, a number of flights will point out whether it suffices. It's important not to forget installing the tiny spacers in between the bearings of the swash driver arms, since they transfer the clamping force of the bolt through the inner ball bearing rings. Failing to include these will bind the bearings, when tightening the bolts onto the hub.

I'll give you a pic of the assembled head and all the unused parts at this point of the build. Yep, I paid for all of those parts in the tray and the bag, unlikely to use them.



full resolution pic: http://rzavelli.home.xs4all.nl/stuff...s/IMG_2218.JPG


Due to absence of documentation, I started with 28mm distance between the pitch link joints. It turned out one of the blade grip ball studs was undersized, causing a lot of joint play. Fortunately I still had some Mini Protos spare ones laying around, which turned out to be the same ones.

Now, it is time to go back to the swash trimming screen of the V-Bar software again. Not to trim anything, but just to get absolute midstick without the gyros being active. Time to set up 0° pitch and blade tracking.

I like to set the frame parallel to the edge of the table, then eye-balling the feathering shaft perpendicular to the frame. Then I use a wrench which just about fits through the main blade holder. Then I sit down on the ground, using one eye to align the wrench with the hub Jesus bolt. Then I look down, near the main shaft collar, to see where the wrench is. It should be in the middle of the main shaft, naturally. This method works way better for me, than messing with a pitch gauge or folding blades together. Never ever have to redo blade tracking at the field with the wrench method. Note, the main shaft isn't perpendicular to the bottom of the frame. You have to look at the wrench in relation to the main shaft at the bottom and the Jezus bolt at the top.

This was the initial angle, with guessed pitch link length:



full resolution pic: http://rzavelli.home.xs4all.nl/stuff...s/IMG_2225.JPG


After some adjusting, I ended up with this:



full resolution pic: http://rzavelli.home.xs4all.nl/stuff...s/IMG_2251.JPG

The pitch link length ended up being about 26.75mm in between the joints.

[Dr. M]

Very nice kojer!

[kjoer]

Thank you!

Tail time!

First, servo horn aligning. Back to the V-Bar swash trim setup screen again to get a centered tail servo with disabled gyro. There's no way to trim the tail servo, other than mechanically, so it's important to pick a servo horn position that is reasonably perpendicular. Position 6 on this horn seemed to work best for me with this particular servo.



full resolution pic: http://rzavelli.home.xs4all.nl/stuff...s/IMG_2261.JPG


Some more annoying servo horn trimming, of course it has to look neat:



full resolution pic: http://rzavelli.home.xs4all.nl/stuff...s/IMG_2282.JPG


The BLS251 servo wires have some thick mantle. I had to file some slots in the tail mount to be able to run it within the frames:



full resolution pic: http://rzavelli.home.xs4all.nl/stuff...s/IMG_2288.JPG


One of the nice features of the Protos and Mini Protos is this bit. It is possible to leave all servo wires at their default length, yet run them inside the frames and hide them from sight completely. Behind the guide pulleys are two canals to stuff the servo wires down and back up. Very nice!



full resolution pic: http://rzavelli.home.xs4all.nl/stuff...s/IMG_2297.JPG


Still have to tidy it up, but you get the idea:



full resolution pic: http://rzavelli.home.xs4all.nl/stuff...s/IMG_2303.JPG


Now, the tailshaft case assembly. By default you have to install two shims to eliminate axial play of the pulley in the tailcase. The kit includes two extra undocumented shims to eliminate further possible play. Any play here will directly affect tail authority, since the whole hub assembly will be able to move left and right. Note the Al. 18T stretched pulley here and the plastic non-stretched 20T stock one.



full resolution pic: http://rzavelli.home.xs4all.nl/stuff...s/IMG_2321.JPG


With one shim either side, I ended up like this:



However, it turned out, for me, the pin had too much play in the tail pulley, causing axial play of the complete shaft. Shims won't help you with that.

Now I had two options:

• File down one side of the pulley, thus reducing the height of the pin slot, then adding extra shims in the assembly to compensate for the reduced pulley width.
• Use fitting green retaining compound to lock the pulley onto the shaft. Easy fix, but more work in the event of maintenance to get stuff apart.

I chose the latter option, using just one shim on either side of the tail pulley. It turned out to be perfect. No feel-able axial play, but free spinning. Be careful with tightening the rear bolt of the tail case, it has a profound effect on tail shaft axial play.


Boom support ends epoxy gluing, I sand the ends to remove the coating and to rough them up, using a bit of tape to prevent sanding further than needed.



full resolution pic: http://rzavelli.home.xs4all.nl/stuff...s/IMG_2337.JPG


A picture of the assembled tail:



full resolution pic: http://rzavelli.home.xs4all.nl/stuff...s/IMG_2349.JPG


I don't particular like the two blade grip ball joints in this pitch link system. This means there are three points on a single line, meaning, if every part isn't exactly nominal, the assembly will be over constrained. This may translate to increased tail slider drag. However, if it works, it works.

Ever since I had the hub set screw of the Goblin 700 backing out, with it just hanging on to the crater in the shaft, preventing disaster, I just mount hubs completely with set screws and green fitting retaining compound to the tail shaft. This is a stock tail, using tail blade grips lacking thrust bearings. An upgraded thrusted version is available.

The Protos tail rod has been revised somewhere in time, it now features a cup style rod that goes over the carbon, similar to the Mini Protos. This solution eliminates the chance of splitting the end, likely with screwing a threaded rod into a hollow carbon rod.

Next up are the motor, ESC and Mini V-Bar mounting.

[kjoer]

Ugh, a conflict in the manual, I didn't notice it earlier. Of course I picked the wrong orientation to optimize the original star shaped servo horn for.



full resolution pic: http://rzavelli.home.xs4all.nl/stuff...n_conflict.jpg




http://rzavelli.home.xs4all.nl/stuff...s/IMG_2354.JPG


Unscrewing the servo horn, I was hoping the Futaba serration has an even number of splines, so the horn would rotate exactly 180°. Of course it didn't, ruining a perpendicular position at the opposite side.

Fortunately I still have identical star shaped horns laying around, so I'll make a new one.



full resolution pic: http://rzavelli.home.xs4all.nl/stuff...s/IMG_2261.JPG