Testing ProModeler DS85 Prototype Servos

Extreme Flight's 48" EXP series planes have set an untouchable standard for planes in the 4 foot class. The original Extra is now over a decade old, a long, long time for any 3DXA plane in today's ultra competitive market. The market changes every day, and planes come and go, but the one constant has the 48" EXPs dominance in this size class.

As the game changed and evolved, we were putting more and more stress on everything, especially the servos, to the point we were asking more from them than they were designed to give. Remember, the HS65MG was designed for planes like the original Extreme Flight 45" Extra on 3s batteries, but the planes have become so super high performance that we needed a little help with a faster, more powerful, and more modern servo. That's where the ProModeler DS85 is soon to come into play.

The Test Bed
Well, what else could it have been but the Extra EXP? These have been my primary plane for the last 10 years and the one I am most comfortable and confident flying. Extras are noted for how predictably they respond to set up and equipment changes, so any time I wanted to try or test anything, it has almost always been on the 48" Extra.

 

  

 

Having already experienced the difference the DS100 made in my 52s, I was really excited about making that kind of improvement on my beloved 48. I needed to replace a crashed one anyway, so this gave me a convenient excuse to build two new ones!

The reason I built two is because the middle of a testing program is a bad time to lose a plane. As you can see, we are well past the performance testing and now it's all about durability. You have to push the plane extremely hard, almost to the point of abuse, because if there's a weak point you have to weed it out now. Whatever you are testing can fail, but in this case it's much more likely I'll make a stupid mistake pushing too hard and bury the plane. Having a back up assures that even in the worst case I'm only a day away from being back in the air.

This was not going to be a time sensitive project, except, as we were gearing up the Extreme Flight Extra EXP V2 was announced. The hope is to have these ready and in production before that plane gets here. The V2 is going to be so nice (the perfection of the perfect plane) plane, and these servos are so superb that the two absolutely deserve each other.

In addition to the servos making the plane fly massively better, this program has given me a most excellent reason for hammering the crap out of the plane and simply enjoying the ride. I've always loved flying this plane and now it's better than ever.

The DS85 Servo
First a big thanks to John Beech of ProModeler for the opportunity to be part of this program. With lots of communication going back and forth, I've already learned more about servos in the last year than the last 40. As a big proponent of the 48" class, I'm delighted to be part of moving things forward, that is, so far forward that there's just never any going back.

The DS85 is going to have everything pilots are looking for in this size. First, the torque is a whopping 85 inches, or roughly enough to sink the Bismark, Turpitz and Yamato all at once! This plays out nicely at speed and in full deflection maneuvers........ no stalling, no blowback, no nothing except the servo doing what you ask it to. This gives you a better feel and a better connection" to the Plane. That and this much torque means the servo is under stressed, and that will show up big in boosting reliability and durability.

One really nice aspect of all of this is that the DS85 fits the servo opening cut in all the 48s, down the point the servo screw holes are the same pattern. I previously has HS5070 in this plane, and the DS85s dropped in bolted right down. Easy, especially if you are retrofitting an existing plane.

When flying this plane with HS70 servos I had to space the rudder servo out about 2/16" because it was bottoming out against the other side of the fuselage. The DS85 is shorter enough that it just goes right in without any spacers. It's always nicer when things fit perfectly.

One difference on my particular plane is that it was already set up for the large HS5087 on the elevator. I had cut the servo opening for the larger servo, but fortunately the ProModeler DS100 fits here too, so that's what I am running for now.

Above are a few detail shots of the components. You can see how beautifully the case is machined. Next to that is the case top which features brass insets where the gear pins locate. Brass wears a lot better than the plastic most case tops feature, but brass mounts keep the mesh perfect. The pins also mount into brass bushing on the bottom, so this is as solid and durable as it can get.

Flying
Testing new equipment can be a little unnerving because you don't for sure know what's going to happen (which is why it's called "testing") to your expensive plane. Buoyed by previous experience with ProModeler servos I more excited about the potential new performance than I was worried something bad would happen.

Testing ProModeler DS85 Prototype Servos 003 from Doc Austin on Vimeo.

Just like happened in my first ProModeler DS100 tests, the plane trimmed out in one pass. I was used to this from flying ProModeler for about a year now, but it's telling this seems to be a trait of all the ProModeler servos I've owned. On a lot of servos the trim shifts from one end of the field to the other and it's really nice to be done with that. Now you trim it and forget it, and then fly the plane forever and never think about it again. I still have not touched the trims on my original DS100 equipped 52" Extra in over 100 flights.

Torque is much more than adequate because I had full control at all speeds, including terminal velocity in snaps, blenders and full throttle tumbles. We were using about 50 before and that was plenty,but having 85 ounces certainly isn't going to hurt anything. We do not have a speed specification yet for this servo, but it seems like it's roughly the same as the HS5070MH, which is a quick little servo.

Testing ProModeler DS85 Prototype Servos 002 from Doc Austin on Vimeo.

Where a quick servo comes in handy for people running stability systems (which I am) is that the servo reacts to the gyro faster and stabilizes the plane quicker. In back to back test with the DS100 and DS150 servos, the faster servo just felt better and I felt more connected to the plane. It's much the same with these servos, and as well as I know this plane that connection really stands out.

The biggest pay off isn't really talked about that much, but it's always ProModeler's micrometer precise centering. A poor centering servo gives you a really, really poor flying plane because it simply won't trim out, and the trim changes from one maneuver to the next. You are essentially flying an out of trim plane, and we all know how much fun that is, right? You can't be precise or even smooth because the plane is always fighting you. It ruins the entire experience.

So far it's been nothing but my favorite plane flying better than ever. I'm flying the plane harder and enjoying it more, all good things. I don't know that I am necessarily flying it any better by I can tell you for a fact the plane is much better.

I'm not sure where exactly we are with regard to wrapping things up, but the precision and performance have already exceeded my expectations, and I was expecting a lot. We just need to breeze through the durability phase, but I am confident we will have zero issues. The servos have already been so good that I have supreme confidence in them.

Testing DS85 Prototype Servos__001 from Doc Austin on Vimeo.