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Friday, May 26, 2017

3DHS 48" Demonstrator__Too Much Joy

Too much joy, you know, like when you are doing something you aren't supposed to be doing and loving every second of it.,

 Remembering when we were young, the times we were doing something completely blissful was usually right before we got caught, and that instant lasts forever when you are flying a Demonstrator. It's so much fun you know that you are being a bad, bad boy. Truly, too much joy.

So, I just had to build a second one. You know, just in case.

My initial reaction to seeing the first photos of the Demonstrator was that, thankfully they finally put a nice landing gear on it, because the old Edge 1.5 Huck this plane is based on flew pretty well. Now it's going to be a nice plane. What caught me out was just how much nicer 3DHS has made this plane. The carbon motorbox, battery tray, anti rotation pins and supports, plus carbon reinforced servo mounts and cowl tabs not only stiffens up the plane considerably (which makes it fly and track better), but the bling value makes the Demonstrator as much fun to show off to people than any plane I can remember.

The capper is the superb printed color scheme with carbon style flames licking over the entire plane. From a cool standpoint, this plane is simply blinding.

Even though that's more than enough, that's not the real story behind this plane. The real joy is the most important part, which as always is the flying. I flew enough 1.5 hucks to know I was going to like this plane, but the surprise was how much better the improvements stiffened the plane, and how much better that makes it fly. I've got to be honest and say the 1.5 in my eye was never as good as the SHP, even for the new guys. Remember the SHP is my baseline plane, and I judge every other plane by how it compares to this. The 1.5 was a decent plane, but the SHP was always going to be better in every way. Now though, the Demonstrator is at least it's equal, so equal in fact that I can't separate them. If I had to choose just one, it would come down to flipping a coin.

As much fun as I have had over the last 10 years flying SHPs, the Demonstrator gives the same kind of giggles, only with sizzling coolness.

Servo Upgrade
I've been using Hitec HS65MGs in my current Demonstrator and while they have been great, after 300 really hard flights they are getting a little tired and I wanted to upgrade for this plane. They have been great, but since this is a new plane, I wanted the very best of everything for it, including servos.

My friends at Hitec RCD were kind enough to send me a set of HS5070MH servos, and the new Demonstrator was a good opportunity to put them into play. These servos run on 7.4 to 8.0 volts, and as such, have much better speed, torque and centering. This is going to show up big in how well the new plane will fly. There's going to be no stalling or blowback, which will give you a more responsive plane. Also, the plane will track like a laser beam with their precision centering. Major upgrade for only a few dollars.

 Also worth noting is that this HS5070MH is under stressed in this application, so they just sort of do the job loafing around. It's like using a hammer to drive a thumb tack, but the benefit is the servos are having such an easy time of it that reliability goes way up.

When I built the Murder SHP two years ago I went with the HS5070MH and they have been off the chain stellar. I beat that plane hard and often, and there was ever going to be a servo that screamed
"enough", it was going to be in that plane. Still, they are going strong.

 Since the Demonstrator is the same weight and size, this servo is idea and about as good of a servo as you can find in this size. The HS5070MH is the same size servo, and in fact even uses the same bolt pattern, but it's a little taller. Hitec kept this in mind when they designed the servo and they did not make it too tall for use in current planes. Basically, you can just swap the out for your HS65MGs and have an instant upgrade.

To feed these servo 8.0 volts, I rely on the trust Castle Creations 10 amp BEC. This is such a good little unit that I even use it in planes as big as my 60" EXPs.
 Power System
By now most readers know what's coming next. Of course, it was going to be a Torque and an Airboss.

But of course.

I started my association with Extreme Flight in 2008 representing the Torque and Airboss brands. That's 9 years of absolutely dead solid perfect reliability, so even if something else was recommended, and Torque and Airboss was still going to go into this plane. In this case it's my favorite of all of them, the venerable, versatile and bulletproof Torque 2814. I have flown this motor on 3, 4 and even 5 cells and it's always had great power, smooth running, perfect reliability and it's very own distinct turbine like sound. On 3s it just sounds like a sewing machine, on 4s it's like a turbine engine with the governor taken off and the throttle jammed open. On 5s it lets out a blood curling howl that's frightening to hear.

For those of you who are replacing their older beloved wire geared 48" Edges, or even SHPs, your Omega 130G will bolt right in and work just fine. The Omega 103 will work too, but you might find it to be a little underwhelming.

Worth mentioning is that if you buy the Torque/Airboss power system with your kit as a combo, you save about $70. That drops the price to where the motor is essentially almost free, or to the point the entire power system is very competitively priced with "budget" power systems that won't be nearly as good. If you already have a power system, that's good too, but if you need one for this plane, there's no better way to go than the Torque/Airboss power system combo.

I wanted to mount the ESC on the bottom of the motorbox, but I could not get the deans plug to come out where I wanted it. I may play around with it later, but for now it was essential to get the article finished and get some video in the can and on the net.

As such, I simply mounted it on the side of the motorbox and the deans plug comes into the battery compartment where it is out of the way for battery change out, but perfectly positioned to plug it into the battery.

Aileron Set UpSport flyers might think this set up looks wrong because the pushrod is not at a straight angle. The reason we set the pushrod this way is because in 3D we run so much throw that you want the pushrod as straight as you can get it at maximum throw. Bolting it to what appears to be the wrong side of the control horn actually gives you perfect geometry at full deflection.

In a major upgrade 3DHS is now supplying double ball link hardware. Ball links give you smoother, drag free operation, as well as eliminating any slop or looseness in the pushrod system. They are also much easier to set up that the old swivel connectors, You just bolt them on and you're done. I love this upgrade.
Elevator Set Up
Again, it's just a simple dual ball link set up. If you follow the manual, it's really hard, if not impossible to go wrong. The kit comes with hardened allen head bolts and lock nuts, so again it's just a simple bolt together operation.
I used the standard arm that comes with the servo and pegged my end points. This gives me slightly less than bevel to bevel deflection, so it's plenty of throw with no danger of the servo binding. Like the rest of my set up, this comes straight out of the manual. The entire plane is extremely well thought out.

You want your pushrods to be as straight as you can get them, so to achieve this for the elevator. I bolted the ball link to the inside of control horn. The alignment is absolutely perfect, which assures smooth operation and good centering of the control surface.

Ruder Set Up
I'm going to cheat a little here and point you to the picture above because it also gives you a good view of the pull/pull rudder cables. The slots in the fuselage come precut, so it's a simple matter to tuck the loose covering into the slot with a trim iron.

Pull/pull systems are not difficult to set up or maintain. You just need to know a few tricks, and you'll learn those on your own after you do a few of them yourself. The only thing that makes me crazy on pull/pull installations is that's it's not easy to do a clean looking installation. You've got the crimp piece and the wire loop and the extra wire hanging out, and to me I just cringe when I see work like that.

I think I've come up with a decent enough looking solution though. First, I slide the crimp piece very close to the threaded adjuster piece, and I pull the slack wire so tight that the loop you would normally see flattens out against the crimp piece. I crimp, run a little thin CA onto the crimp piece, and once the glue sets up I cover the whole thing with some heat shrink tubing.

It's not perfect, but it looks so much better than having everything exposed that I an reasonably happy with it. I am probably going to always have one of these planes, so I will work on making something even cleaner looking. I have a little bit of OCD on things like this, which always drives me to trying to do things better.

Here's what the cables look like hooked to the servo. You use that standard Hitec HS65MG servo arm that comes with the servo. Again, I got the crimp pieces as close as I could to the connector pieces, got the loop wire as tight as I could and heat shrunk the entire thing to make a neater looking package.

Radio Installation

Friday, May 19, 2017

Working With Pull Cable Systems

Еще раз спасибо моим друзьям в России, которые читали блог 1428 раз в этом месяце. Большое спасибо за отличную поддержку и, пожалуйста, расскажите всем своим друзьям. Также, это специальный привет моему другу Терранозавру!

I've had so much fun with my 48" 3DHS Demonstrator Edge that I wanted to build another one. I've been threatening to write an article on pull cable set up and this gave me an excuse to build another Demonstrator even though my first one is still in terrific shape. Maybe I'm just greedy.

For those who have never done a pull system, it can be quite intimidating, but it's really just as easy as using a pushrod, just different. Like anything else, you need to know a few tricks and you learn those by doing them, and hopefully, from reading this article.

Setting Up The Pull System

My first pull system had me scratching my head and cursing a little, but I learned enough from that to make subsequent ones go smoother. It's not that hard and there are no mysteries. After you do a couple you will wonder why you were intimidated to begin with. What I'm going to try to do is show you some of the little tricks I learned the first few times.

If there are any hard and fast rules they are that you want a drag free and slop free system. The rudder has to move smoothly with no drag coming from a bad hinge job or ill fitted tailwheel assembly. The swivel connectors on the servo arms also have to have no drag on them, and as little slop as you can manage without getting them so tight they drag. If there is ever any doubt on any part of this, always go for smooth and drag free, slop free operation. This is critical for good rudder centering and makes for a good flying and nice tracking plane.

Cleaning Up The Cable Exits
The slots for the cable are already laser cut into the fuselage sides, and the covering is slit so the wires can pass through. The first step it to tuck the covering into the slot with a trim iron. Get them out of the way so they don't put any drag on the cables. You can either cut them flush with the edge of the slot or tuck them in, but tucking them in makes for a neater and cleaner looking job. Here you want to use low heat to avoid the iron sticking and pulling the printing off. Take your time, do a neat job. I think you'll agree this looks a lot cleaner than leaving it loose.

The Cable Ends
Now, thread the ball link onto the threaded connector piece. You can either hold the threaded connector with a pair of pliers and spin the ball link on by hand, or chuck the connector up in a small drill and spin it into the ball link. If you have arthritis, using the drill will make life a lot easier.

The connector will be easier to handle this way because it gives you something to grip. I suggest threading it on all the way, then backing it off five turns or so. This will give you some additional adjustment should you need it later.

With any operation, the cleanest and most tidy job is going to be the best solution. The least clean part of any cable installation are the cable ends and crimp pieces, and I've done my best to make that neater. Here is how the manual calls for the cable ends to be assembled. This works really well, though it's a bit messy for my taste. We are still going to do it the way the manual calls for, though we are going to tidy it up a bit.

Follow the manual and you will get what you see below. Again, this works well, but we're going to clean it up a little. I've put a battery on the ball link to hold it down and aid in getting a better photo.

We are not really going to deviate from the manual here. We are just going to go one step further in making it look better. Again, the cleanest solution is the best one. What I try to do is eliminate the loop in the cable and the extra wire sticking out. First, I pull the wire in the loop tight enough to take the loop out. This goes a long way toward a cleaner appearance. Then I move the crimp piece closer to the threaded end piece to make the whole thing smaller and visually less intrusive.

Once you get it all lined up. take a pair of pliers and smash the crimp piece flat. Just to be sure, put a drop of thin CA on the wire and hold the piece so gravity helps it run into the crimp piece. Snip off the loose end of the cable and the whole thing looks a lot better. It's still pretty ugly. but we're not quite done.

Finally. I use a piece of heat shrink tubing to cover the whole thing up and make a nice presentation.

Setting Up The Servo Arms
Now we take care of the other end.  Here I am using the standard Hitec double arm that comes with the servo and the 3DHS swivel connectors. These are nice because they afford easy cable tension adjustment.

First, drill the outer holes in the servo arm with a 5/64  size drill. I use a little hand drill from the Hobbico set, but in a pinch you can get away with hogging it out by spinning #11 Xacto blade in the hole. Drilling can leave behind some flash around the hole, and this can interfere with the swivels moving smoothly. I use an emery board to lightly sand the top and bottom of the arm. Good, smooth operation will help with proper servo centering.

On the newest 3DHS swivel connectors the threads on the end are a little tighter so the nut spins on a little harder. This is a good thing because it makes it harder for it to come loose. Get the nut as tight as you can get it without introducing any drag. Again, you always want smooth, drag free operation on any control system.

As you can see, the threaded end is a little long, and you have a few threads sticking out. The reason for this is you want to put to put CA on these threads to lock the nut on. I like to use a T pin to apply some thin CA to the exposed threads, and after that sets up, a dab of medium CA. This assures it's not going to come apart.

When you put the arm onto the rudder servo, use the sub trim in the transmitter to center it.

Hooking It All Up
With the cables attached to the control arm on the rudder and cables run forward into the fuselage, now it's time to hook them to the servo. Here I run the forward threaded end pieces halfway into the swivel connector,  and this gives me adjustment both fore and aft, and remember, we have some adjustment in the rear if we need it.

Now you want the rudder to stay centered so you can get the cable tension close, and for this I usually tape the rudder counter balance to the fin. Since the Demonstrator uses printed covering, I don't want to risk damaging it, so I have the wife or a friend  pinch the two together. 
I like to install one cable at a time because it's easier that way and you have less chance of mixing the cables up.  You want the cables to cross over top of each other inside the fuselage so they line up straighter to the servo. By doing one cable at a time, you simply start with the left cable and attach it to the right side of the servo arm and the right cable to the left arm. I don't know why, but I always start with the left cable.

 Make sure you slide the crimp piece onto the cable first.  Starting with the left cable, run it through the right side forward threaded connector piece. Pull the cable tight. You want to be careful that you don't pull so tight that you start breaking things, but you want it tight enough that you won't run out of adjustment later. Usually the cables end up not being as tight as you thought you had them, so get the slack out. If it's either too tight or two loose, we left ourselves some adjustment by centering the forward connector pieces in the swivel, and remember we also left ourseves some emergency adjustment at the rear with the ball links.

 One neat trick here (see above) is to get the cable tight, then bend it backwards at the connector. This will help it stay tight and not slip while you are running the wire back through the crimp piece. You can see I pulled the wire tight and then folded it over the connector. You can pinch the cable down on the connector with one hand and it's not going to come loose. Then you slide the other end into the crimp piece with your free hand (which has slid back out of sight in the photo).

Like so............

Now you do the loop, which I did not get a picture of, but it's the same as we did on the other end and the same as in the manual. Again, I like to pull the loop tight,  but also again, be careful you don't slip and start breaking stuff. If it's all good and still tight, smash the crimp piece down to lock that part of the adjustment in. Apply some thin CA to the crimp like you did on the rear and it's almost done. Put a paper towel in the bottom of the fuselage just in case you spill any CA. From there, snip off any excess wire, remove the threaded end pieces from the swivel and use heat shrink on the end and crimp pieces.

Do the other side exactly the same way and you're almost home. Yes, I am well aware the rest of the radio installation looks like a rat's nest, but we'll clean that up later

You may notice that my connectors did not even need adjusting. I got the centering and tension
perfect just by pulling the cables tight. Like I say, they normally come out a little looser than you planned, and keeping the slack out to begin with made it perfect. After you do one or two of these you can expect the same kind of results. None of this is a mystery. You just need to do one or two to get used to it, and then it's easy as pie.

Now all  the hard stuff is all done now. All that is left is the final adjustment.

Odds are pretty good you have it almost perfect. You want the cables tight enough that there is no sag in them, and there is no slop in the rudder. On the other hand, you don't want to get the cables guitar string tight either. That will kill the centering. Just adjust the cables so there is no sag in them, and no tighter. Assuming the rudder and swivel adjusters move smoothly with no drag, the rudder should center perfectly. if not, you probably have it too tight.

Slide the forward threaded connectors in or out of the swivel connectors to get the rudder perfectly centered, then tighten them down.  Generally, you don't want the cables so loose that you can move the rudder, and you don't want them so tight that the rudder doesn't center properly. The best rule of thumb is to get them tight enough that they don't sag, and no more. If you get them guitar string tight the rudder will center poorly and eventually the servo will burn out. If you get them too loose the rudder can move when the servo doesn't and it will center poorly to boot, which is never good.

Another good rule of thumb is that if the rudder centers well, you are pretty close. Finally, as long as the rudder will repeatedly center, leave it alone!  If you get it right now, you may have to adjust (usually tightening) the cables once or twice over the lifetime of the aircraft, but outside of that, it's pretty maintenance free. A little patience in getting it right now pays the dividend of you not having to mess with it later.

Generally I try to take a little pride in my writing, but this procedure has been challenging to put into written word. I tried to explain this to a friend out of state over the phone and I did a poor job. Later he visited me and brought his new Demonstrator. It was finished except for the pull system, and I showed him how to do it in five minutes. Showing was a heck of a lot easier than explaining, and infinitely easier to understand, and I tried to keep that in mind when I wrote this. I hope you will find this clear and helpful.