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Wednesday, March 4, 2015

60" Laser EXP__Finally

As much fun as I had with the Laser Sport and Laser HV projects, the next step would most naturally be the 60" Laser. Both the previous projects were in the yellow/white/blue/silver scheme instead of the usual Leo Loudenslager inspired Budweiser-style livery. The scheme is so attractive that I decided to continue that theme on my 60" Laser.

For a lot of reasons I have been unable to put a 60" Laser together until now. Part of that was available finances, but also the 60" Yak came out this year. I wanted to replace my beloved 60" Extra, so all of that soaked up the funding. Along with my 64" MXS, there is just nowhere to store one more larger plane in my small house. As it is, the new Laser is going to have to live on the floor in the gym until I destroy something else to make room for it!

I did get a chance to fly my friend Rob's Laser early last spring and loved it, but you can't really fly your friend's plane hard enough get a good assessment....not if you want to keep your friends, that is! Still, I liked the plane right away.

Looking back, it was my first experience with the kind of eerie stability the Laser shares with the 60" Yak. It's so smooth, solid and easy that it just doesn't seem right. Anything that seems so right and feels so good is usually a trap, right? At the time I thought it was odd, until I got my Yak and it felt the same way. The harder you push the Yak, the better it gets and that's what I am expecting once I get my own Laser and start flying it hard.

The big Laser is the one EXP in the 60" lineup that I have not yet owned, so it's definitely time to pick one up and get started.

The Kit
Holy cow is this thing huge! The box is so massive I almost wondered if they had sent me an 74" Laser by mistake! Unpacking the plane it becomes evident pretty quickly that the big Laser is a large airplane for it's wingspan, even by EXP standards. The fuselage is simply immense. Also large are the fin and rudder. Everything is just big on this plane.

Hardware is almost identical to the other 60 size EXPs. If there is a difference, I can't find any. These are the same ball links and pushrods we are used to working with, which is great because they give a nice, tight and slop free connection from the servo to the control surface.

Again featured is Extreme Flight's most excellent tail wheel assembly. I love this unit because it is very simple, and if you have a problem you can change the whole thing at at the field in about thirty seconds with just three screws. It is easy to set up and easy to maintain.

The last few EXPs I have gotten featured an improved tailwheel steering arm. The new arm features a bigger center section with more area where the two pieces are pressed together. I've been running these arms on my 60" Yak, 60" Extra and 48" HV Laser and they are staying solid. If there was one thing I would have improved on the EXPs, this would have been it, and now it's done.

Worth noting is how large the air intake nostrils are on this plane. The laser has a very wide cowl, especially around the cheek area, and this allows for a huge cooling inlet area. The kit comes with air deflectors that mount on the motor box and direct more air to the motor, but I don't think they will be necessary, even in the Florida heat.

Above we are about six hours into the build. All that's left is installing the servos and hooking up the pushrods, and that's only maybe an hour's work. I like to pre-fit the servos and remove them so I don't risk getting glue into them when I put the tail on.

That, and at the time of the photos, I didn't yet have the servos. I used a spare HS5245MH to drill the screw holes (they are identical to the HS7245MH we will be using). All that is left now is screwing the servos in and hooking up the pushrods.

The only thing I worry about on the 60 size EXPs is getting the right holes cut in the fuselage for the servos, but my Yak and now Laser came pre-cut, and nicely too. This took a lot of stress out of the build because I have gotten this part wrong in the past and had to patch things up, not something I enjoy on a brand new airplane.

On this model, installing the stabilizer took a bit more time than usual, but the reason is, admittedly, a bit odd. I slid it on and simply eyeballed it to get it sort of straight enough to begin measuring. Unbelievably, it was absolutely dead on perfectly aligned all the way around. Anything that is this easy is usually a trap, so I started to get a little paranoid that something was wrong or that I was measuring wrong or something.  I must have measured it fifty times because I could not believe how straight it was. It was so easy that I was getting worried, so I set it aside and installed the pilot. Some times you just gotta walk away for a few minutes and do something else instead of getting stressed out about one thing. When I came back to the stab, it still measured out perfect, so I nailed it down with CA.

Mostly the whole thing went together almost before I knew it.


Servos Something different for this project are the HS7245MH servos that Hitec Multiplex was kind enough to send me. I've used these on my new Extra and am very pleased with them. High voltage (HV) servos are the current rage in this size class of planes. In fact, while Extreme Flight used to recommend the 5245MGs, they have updated their recommendation for all 60" EXPs to the 7245MG. These were the recommended servos for the Laser from the beginning.

I had held off on trying these servos because they are a bit expensive compared to what I am used to using, but expensive servos are generally expensive because they are worth it. The additional torque and speed will come in handy, and the better centering will compliment the plane's precision nature. These servos made the Extra a better flying plane so there was never going to be any other choice for this plane.

Motor Type: Coreless
Bearing Type: Dual Ball Bearings
Speed (6.0V/7.4V): 0.13/0.11
Torque oz./in. (6.0V/7.4V): 72 oz-in/89 oz-in
Torque kg./cm. (6.0V/7.4V): 5.2 kg-cm/6.4kg-cm
Size in Inches: 1.28 x 0.66 x 1.29
Size in Millimeters: 32.4 x 16.8 x 32.8
Weight oz.: 1.20
Weight g.: 34.0

I haven't had the chance to put a lot of flights on the 7245MH in my Extra yet, but I was very impressed with them. With more torque and holding power they won'[t be working as hard, which hopefully means they will be even more reliable and care free than my trusty 5265MGs.

Having said all of that about the HS7245MH, my HS5245MGs were still dammed good servos. I still  have my original set in my MXS, and both my Yak and Edge also use the 5245MG.

BEC Set Up
Once again I'll be running a Castle 10amp BEC, just like I did on my 60" Extra. This time I am a lot happier with my installation because it is out of the way while still in the airflow.

If this text looks like a copy/paste from the Extra article, that's because it is. The boss figured all the control set ups on the first 60" EXPs, and they are all virtually the same. All the EXPs use dual ball link hardware and G10 control arms, so if you have built one, that's as good as having built them all. It's nice to go into a new build having seen all of it before in the other EXPs. I pretty much knew exactly what to expect for the build and the set up.
I went for every bit of elevator travel I could steal. The laser is really huge and all of that area generates stability. To get the most agility out of the plane I can, I really needed to watch my control movement and get as much as I could. After the hinging was done I can move the elevator up to about 80 degrees from center, and that was with a pretty tight hinge gap. I've hinged so many planes I am almost starting to get good at it!
From there I believe it is absolutely critical to seal your hinge gaps. I suspect some people get tired of hearing me say it, but I believe it's that important. Gap sealing has it's greatest effect on slow speed control response, so to me that just screams "Ultimate 3D tweek!" Sealing also reduces the chances of high speed flutter, and believe me, this Laser is going to spend a lot of time going very, very fast. 
Servo Arms 
 I used Hitec's PN55709 arms when I rebuilt my 64" MXS and later when building my new 60 Edge, Yak and my newest Extra. These have held up really well, and they just happened to be the exact same size as arms I was using previously. Nothing changed here except the servo arms fit tighter on the servos, which makes the plane fly much more precisely. We are spending a lot of money to build precise flying planes, so you have to pay attention to details like this.
These linkages are similar to those found on the 48" EXP series except the bigger planes use a slightly beefier ball link. I like these a lot because you can really tighten down the bolt that secures them and that won't make the ball link stiffen up like happens with the smaller ball links. I put a lot of effort into getting the my ball links operating smoothly with no drag, so this saved me a lot of time.

As is customary on all my planes, I use Dubro 2mm hardened allen bolts and double nut all the ball links, then put a drop of thick CA on the exposed threads. Like this they will never come off on their own, but if I want to remove the ball link, I simply back off the outer nut and that will shatter the CA.

Aileron Set Up
Here you can see that I used the outermost hole in the smallest servo arm that comes in the pack. With my end points set at 140%, this gives me about 32 degrees of aileron, which, believe me, is enough on this plane. I have flown a friend's Extra that had more throw and I could barely hang on to it. With this set up  it feels just a touch faster than just right, to me anyway.

 Elevator set Up
Once again, we go for the gusto on the elevator. Using what I learned from my other 60" planes, this time I was able to get 75 degrees of elevator throw! I used the longest double arm that comes in the Hitec PN55709 pack and cut one arm off. Like this you get the equivalent of one more hole to move the ball link out to. I hinged the elevator with a reasonably tight gap and was still able to get that much. Even if I had a longer arm I don't think there's anything left. It's almost bevel to bevel.

I had to trim the arm just a little to clear the bottom of the stab. If I had this build to do over again I would cut maybe 1/8" off the bottom of the servo opening and drop the servo down just a little. I don't need to get any more throw .... just a little more clearance.

You may notice this set up is a little different from the manual in that the servo is turned around (opposite from what is in the manual) and the output shaft is closer to the tail. This way I was able to thread the ball links deeper on to the pushrods. They are very close to being totally bottomed out on both ends. In fact, they probably are past that because I used a drill to spin them in. Since they are translucent white, I could see how deep the pushrod was going in and stopped before I screwed the pushrod out the other side! I think I had to back one ball link off a couple of turns, but outside of that, they are screwed as deep onto the pushrod as they will go. It would take a nuclear explosion to pull one of those pushrods out.

If you try this, you may very well ruin a ball link, so make sure you have a few spares around.

Rudder set up
Again, we use the longest arm from the pack. Since the Extra is so stable with it's long tail moment, you want all the throw you can get here. I generally get it to hit the elevator and then back it off a little with the endpoints. Using the outer hole in the arm was so much throw that I have to dial my end points back to around 100 or so. Instead, I went in one hole and maxxed out my endpoints.

Unfortunately what was perfect building weather (cold, rainy) is not so good for testing a new plane, so we haven't had a chance to fly the plane yet. We'll save that for a new article once we have a few flights on the new Laser and get some video too. Hopefully that will happen quickly.

Spoileron Mix
I've been playing with a 50% spoileron mix on some of my 48" planes, Laser, but never really put enough effort into it to give it a fair chance until recently on my new 48" Laser. With spoilerons, the ailerons will work together in the opposite direction of the elevator, though they remain independent and still work as ailerons too. Spoilerons come in real handy for a few things, but we'll get into that later.
At first I didn't like the effect, but it turns out that 50% is too much mix unless you are going to be turning it on and off all the time depending on what you want to do. One of my buds over at RC Groups says he likes 37%, so I set mine up for 30 and tried it again. This time it was much better. I can leave the mix on full time and the plane even harriers and hovers better this way. I'de say the 48" laser with the mix harriers very close to as well as the 48" Edge does, which is saying something. At this point, it is so close to being right that I may try 25%
With the mix on the plane will do the most straight down elevator drops you have ever seen ...... totally sick. With 50% mix the plane fell too fast, but at 30% it's much better. Also, parachute maneuvers are more interesting because instead of popping to a stop the plane will rotate to flat, but keep sinking at a high rate of speed. Essentially you are using a parachute to enter a high speed elevator maneuver. With 50% mix the thing would fall so fast that I almost put it in the dirt a few times, but with 30% I can arrest the speed quite easily with power. In fact, I did a parachute into a high speed elevator and rode it all the way down into a perfect harrier landing.
I don't want to get too much into the flying aspect of the spoileron mix just yet because I think maybe this deserves it's own article. The mix is definitely very interesting to play with, and it also opens up the envelope of things you can do with the plane. This mix will be on the 60" Laser, though I suspect I won't mess with it much until I have a good feel for how the plane flies without it.

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