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Thursday, December 14, 2017

52" Slick__More Fun With Hitec HS5085MG Servos

Doc's Disclaimer: Extreme Flight recommends Hitec HS-5087MH Digital HV Premium Metal Gear Micro servos for this plane. Using HS5085MGs in this plane is something I took solely upon myself to try.

The spectacular new 52" Slick and Extra EXPs are selling so well that occasionally retail outlets will run out of the recommended Hitec HS5087MH servos. When this happened during a build of my latest Extra, my friends at Hitec recommended I give the HS5085MG a try. That project remains a delightfully surprising success. I love that plane and fly it often. You can read about that in Even More Reasons To Fly The Extreme Flight 52" Extra EXP. That project went so well, it was only natural to want to try the 5085s in a Slick 580.

While the 5085 works really well for me in the Extra, the Slick 580 could be a completely different story. The Slick has a very tumbly, gyroscopic nature, and in a hard snap or tumble it can almost chew it's own tail off. The Slick is capable of some pretty incredible violence, and a much harsher test of a servo than the Extra. With this in mind, we were going to give to give it a try!

Worth noting is that the Hitec HS85MG, HS5085MG and GS5087MH are all built on the same servo case. Therefore, it's external dimensions and mounting holes are the same, and all three of them will happily drop right into the 52s pre-cut and pre-drilled servo openings. We used the HS85mg and 5085mg for the better part of a decade in the 51" Slicks, and with near perfect reliability too, so it is always confidence inspiring to work with products that have performed so superbly in the past.


Specs And Stuff
Mostly I have found Hitec servos suit just about everything I have flown in the last ten years, so I don't spend a lot of time pouring over specs and comparing servos trying to find that extra one ounce of torque or tenth of a second in speed. I'm not a spec guy and this isn't a tech blog. I just share what works for me.

 I just fly them hard and they either work or they don't. So far I have been happy with all my Hitec servos, but if I ever found one lacking the plan was always to upgrade to the next best Hitec servo, which so far has never been necessary.

  However, I know some of you want these details, so here we go.............

HS-5085MG Servo Specifications
Performance Specifications
Operating Voltage Range (Volts DC) 4.8V ~ 6.0V
Speed (Second @ 60°) 0.17 ~ 0.13
Maximum Torque Range oz. / in. 50 ~ 60
Maximum Torque Range kg. / cm. 3.6 ~ 4.3
Current Draw at Idle 3 mA
No Load Operating Current Draw 290 mA
Stall Current Draw 2150 mA
Dead Band Width 2 µs
Physical Specifications
Dimensions (Inches) 1.14 x 0.51 x 1.18
Dimensions (Metric) 29.0 x 13.0 x 30.0
Weight (Ounces) 0.77
Weight (Gram) 21.9
Circuit Type G1 Programable Digital
Motor Type 3 Pole Metal Brush Ferrite
Gear Material Metal
Bearing Type Top Ball Bearing
Output Shaft (type / Ømm) Standard 24
Case Material Plastic
Dust / Water Resistance N / A
Connector Gauge (AWG) / Strand Count 28 / 20 

Advantage Of Simplicity
The 5085 is a 6 volt servo, and this plays out in a simple installation that does not require a separate BEC and it's associated rat's nest of extra wiring, solder joints and complexity. You simply plug the Airboss 80 straight into the throttle channel of your receiver, let the Airboss' onboard 6 volt BEC do it's thing, forget about it and fly. Like this this Airboss' on/off safety switch still works, an important part of my preflight procedure for making sure I don't have a nasty propeller accident.

Here you can see how well the Airboss snuggles into it's designated location. With the absence of an separate BEC, the installation is much cleaner with less wires and less clutter. The standard Airboss installation and operation is what I have become used to over the last 10 years and, as such, this is the way I like doing things.

More Simplicity
Something else worth pointing out is how Extreme Flight has cleaned up the radio installation. Using hooks cut into the formers, you can restrain the servo wires so they don't flop around, and they stay out of the way when you are working in the radio compartment. This also looks very professional, so it's a win/win.

Once again I relied exclusively on Extreme Flight's brand of aftermarket accessories. I love the servo extension and servo mounting screws. For this project  I was a little short on funding and was not able to buy the terrific Xessories servo arms, but I can always add those later. You can read more in Once again I relied exclusively on Extreme Flight's brand of aftermarket accessories. I love the servo extension and servo mounting screws. For this project I was a little short on funding and was not able to buy the terrific Xessories servo arms, but I can always add those later. You can read more in Xessories Update.   

Set Up
Nothing new or exciting here because all that is important is that it simply works.
I have notched that the ball links that have come with my last few kits work much more smoothly with less drag. I usually tinker with the ball links a little to loosen them up, but on this kit all I did was bolt them on and they did not need any further attention. I was so easy I felt a little guilty, so to ease my conscience I put a drop of silicone oil on each one. I used to put a lot of effort into this part of the build, because it was as important to get it right as it was annoying. It's nice that now it's a bolt on, no tinkering operation.

Elevator Set Up
Nothing special here except Extreme Flight's excellent and exclusive G10 servo arm extension. I do something a little different from most people here, and instead of using the arm that comes with the servo, I use the anodized blue metal arm that comes with the HS7245MH (and other  Hitec) servo. This is a metal arm that will not get sloppy, wiggle around on the servo output shaft, and give you a sloppy connection. The arm stays tight, so I believe this is probably the best arm for this application.
Aileron Set Up
Once again I turn to the reliable Hitec PN55709 arm set, and I use the shortest arm, with the ball link on the outer hole. The Slick seems to have a slightly faster roll rate than the Extra, so for this plane I am most comfortable with the end points set at 125%.

 Rudder Set Up
At the risk of being repetitive, once again it's the Hitec PN55709 short arm.  I have the end points on my transmitter cranked to the left, and I only have to back it off 10% or so to the right.  This gives me full deflection in both directions.

While all of this seems too simple and too easy, that's actually a good thing. Simple means it is much less likely to ever fail, and easy means you are more likely to get it put together right. Simple and easy are two extremely solid concepts that pay big dividends on any build.
I was pretty confident these servos would be really good in this plane, and that's exactly how it worked out. The 5085 is about 10 years old (maybe even older). It is fully developed and refined, so they have plenty of speed, power and precise centering.

Just like the 5085mgs in my Extra, the Slick trimmed out all by itself. I did not touch the trim levers all day. It was perfect. The Slick also stayed trimmed. This tells me that centering is exceptional, but we knew this from the 5085 Extra test.

Speed is really good and I can't tell much difference between this and the 5087mh. No stalling, no blowback and I expect the same kind of reliability I have always had with Hitec producys.
Generally I am tickled silly with this plane for a lot of reasons. It was an effortless build, the build was also flawless (a first for me) and it flies perfectly. This might be the nicest plane I have ever owned. As far as overall project satisfaction goes, this one gets a 100%. 

We usually try to shoot two or three videos, but today was so much fun we forgot that's why we were there! I flew the Slick all day and by the time we got around to shooting we were all tired and hungry. We'll try to get more tomorrow and maybe do a separate flight report.

Slick EXP__Testing 5085MG from Doc Austin on Vimeo.

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