Roban 600 Size UH-60 Blackhawk Build

[PawPaw]

After receiving my 600 size UH-60 Blackhawk from MRC I decided a build thread might be beneficial for prospective purchasers of this and SH-60 variants. When I unboxed and inventoried the kit contents for potential warranty issues (there were none) one thing was immediately obvious: this kit will require a little structural enhancement in a critical area. Typically, any builder of a Roban heli might choose to add extra epoxy at ply to FG joints but this kit definitely requires that plus the addition of another structural member in the tail cone to mitigate a future disaster.

[PawPaw]

The tail cone, as designed, is too thin to support higher than normal landing loads imparted by the tail wheel. The ply support structure is intended to transmit those loads to the fiberglass skin, which is thin in this area. I plan to use a mixture of epoxy and milled fiberglass to fillet the open joints in the ply support. Additionally, Roban intended the tail cone be attached to the fuselage with an epoxy joint and they did reinforce the tail cone in that area with a strip of carbon fiber. However, the problem is that the tail cone needs longitudinal reinforcement between the tail wheel support structure and the fuselage...at least to the mating glue joint. I plan to glass in a 2mm x 12mm carbon fiber bar at the tail cone bottom seam line then allow it to overlap the mating joint when I glass them together.

[PawPaw]

This Blackhawk is large for a 600 size at 150cm long. Atypical for Roban, the cockpit and cabin areas were sprayed OD green and not left bare. Big plus for me. The first assembly task I zeroed in on was the LG install. I had a few problems with my 500 AH-64 Apache LG so wanted to see what I was in for here. Sure enough, the Dremel was needed to open up the main shock strut top mounting hole (easy) and the lower main strut exit hole (easy) to allow the main shock strut to pivot aft a few degrees upon compression. NOTE: If you don’t enlarge these 2 areas the top mounting bolt will crack the fg and the shock strut will not compress more than 1/8”, and is guaranteed to break the fg on a hard landing. That’s because the arc of the lower swing strut forces the main shock strut aft when it tries to compress and the factory slot is too narrow for movement. The pics show the enlarged areas and the unmodified lower slot and the lower swing strut arc.

[PawPaw]

Not a major issue, but I will epoxy a small 1/8” backing plate inside the lower LG swing strut mounting recess. The strut bracket is secured with a single 3mm screw into the thin FG as designed, and is essentially adequate as the lower swing strut is unloaded but it’s good practice to back those screws. For info the Krylon Camo Ultra Flat rattle can is a 99% match for Roban’s OD.

[PawPaw]

It appears Roban got it right with the main LG compression strut springs in this UH-60. Unlike the 500 size Apache, the springs won’t be fully compressed by its weight alone leaving reserve at landing. The tail compression strut, however, has limited travel either by design or manufacturing or assembly error. Mine has 50% available travel (position of stop screw in slot). I’ll live with it for now rather than risk the steel stop (grub) screw stripping the threads in the aluminum compression strut from trying to loosen a thread-locked assembly. May change my mind later.

[sfcfury]

Ohhhh this is what you been getting into today! lol

[PawPaw]

I just got the LG on it so it would sit on a shelf without scratching the belly and so I could take the box outside. Rest of the day has been painting and mounting the new blades on the Apache and grocery shopping.

[PawPaw]

Another great feature of this kit is the option to build it as an -A model or current HIRSS equipped version. There is no manual in the kit itself but the manuals available online show that at one time Roban included both the -A model square tailplane and the current version tapered one with the 600 UH-60, but not now. Tapered only. I plan to add the HIRSS so tapered tailplane is correct but the scale purist wanting an -A might be turned off.

[DCORSAIR]

Woohoo, someone got a new toy, looking forward to your build...

[PawPaw]

Sfcfury made me do it.

[sfcfury]

Sfcfury made me do it.

I needed somebody to distract this dog from my house!!

[PawPaw]

😂

[PawPaw]

One thing worth mentioning to prospective builders of this UH-60...or any Roban heli in my experience (5 and counting)...is that for whatever reason the recesses for add-ons molded into the fuselage never seem to match right and left. One part will fit its recess perfectly on one side but will require the Dremel on the other. Not at all hard to do but a fact of life it seems. The HIRSS units on this one both needed a little shave but due to their continuous compound curves I compromised to get the fit I was comfortable with, which was not perfect. Those willing and able (not me) to repaint the heli would easily fill and sand the seams instead.
I used the Dremel sanding drum to lightly remove enough of the gelcoat to get a decent fit. I did not cut into the cloth but would have if it was required since it is not a structural part. NOTE: The HIRSS internal ducts were not glued in at the factory and are removable. Nice feature.

[PawPaw]

My Chaos 600 mechanics just arrived so first order of business with it will be to conjure up 3.5mm spacer plates for the 2 vertical drop down shaft bearing blocks included in the kit. The original Align Trex 600ESP mechanics, which this and all other Roban 600 fuselages were designed for, has 47mm frame spacing while the newer PhoenixTech 600 and Chaos 600 frames are 54mm. I’ll probably fix it the hard way because that’s the way I do everything else. 🤔

[DCORSAIR]

My Chaos 600 mechanics just arrived so first order of business with it will be to conjure up 3.5mm spacer plates for the 2 vertical drop down shaft bearing blocks included in the kit. The original Align Trex 600ESP mechanics, which this and all other Roban 600 fuselages were designed for, has 47mm frame spacing while the newer PhoenixTech 600 and Chaos 600 frames are 54mm. I’ll probably fix it the hard way because that’s the way I do everything else. 🤔

I was told that the kit comes with the spacers for the bearing blocks back when I did my 600 Roban Bell 212??

[PawPaw]

Hmmmm...better go check all the hardware again. If you’re right I’m sending my first born.

[PawPaw]

No spacers. My current idea is to chuck up an end mill bit in the press and carve some aluminum or micarta. Jury’s still out.

[DCORSAIR]

No spacers. My current idea is to chuck up an end mill bit in the press and carve some aluminum or micarta. Jury’s still out.

I had these in my bag of parts that came with my Roban 600 Bell 212 conversion kit, I think Delta 106 shows these on his UH-1 conversion, they are spacers for the vertical tail transmission shaft bearing holders, is that what you need?
Hope I didn't misunderstand what your needing?

[PawPaw]

YEAH BUDDY!!!!!

[PawPaw]

From experience I’ve learned it’s much easier to iron out any mechanics mounting issues early, so I assembled the Chaos frame and added the gears and swash to reveal any clearance issues inside the fuselage. There were none, with the exception of the necessity to remove the pushrod swing arm from the bottom of the gearbox before sliding the mechanics back. There’s plenty of room to reinstall it and reconnect the ball ends once in place, it’s just that the ply tail wheel support structure impinges on the swing arm if left in place during install.