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Thursday, March 19, 2015

Laser EXP__The Spoileron Files




 
 3D flying has morphed into something completely different, though not necessarily new. The earliest 3D I saw was just a bunch of hovering around, but as pilots progressed and the planes improved, we started seeing the same planes performing high energy and precision maneuvers. Since in many of these maneuvers the wing is not stalled or partially stalled, this is not really 3D flight. Now we are into something else, but by combining high speed precision, high energy snap and tumble maneuvers and post stall 3D, we are really flying "Extreme Aerobatics."

As such, this means extracting as much performance out of the airframe as you can get. The elite manufacturers already make very capable planes, but even after they are done most extreme aerobatic pilots are still looking for more. This is why the servo debate and the power system debate rages on even after we already have amazing equipment. As hobbyists and tinkerers, this is simply part of our nature.

Spoileron and flaperon mixes are nothing new, but until recently they have not been considered essential on an aerobatic aircraft. It is the constantly evolving nature of extreme aerobatics that demanded we use them to get even more out of the aircraft, and this seemed like a really good challenge. It was also free and I would not have to build anything to try it!

The short version of the spoileron mix is this: The ailerons move up and down, coupled with the elevator and in the same direction as the elevator, but also remain independent enough that they can also act as ailerons. As the elevator goes up (or down), so do the trailing edges of the ailerons. This essentially under cambers the airfoil and causes it to create less lift. Since I am not an engineer, that's the best description you are going to get!

Set Up
With a modern computer radio this is easy to set up. I have not had a chance to set up a Spektrum yet, but on Futaba you just go to ele/flp mix, turn it on and assign it to a switch. There are times you won't want to use the mix, and this is why you put it on a switch. The mix improves some aspects of flight and hampers others and a switch allows to choose when to use it and when not to.

The default is 50% mix, but I found that to be too much for my purposes. Everyone is going to have to tinker with it and experiment with it for themselves, but I settled in at 25% for a lot of reasons I will explain a little later.

Of course, you have to run your ailerons on two different channels. If you are using a Y harness you can't make this work. I like separate channels because it allows me to sub trim the ailerons independent of each other and this makes set up much easier. Being able to use a spoileron mix is just a bonus.

Flying
 
Using a lot of spoileron mix can make the plane do some weird things, and in the beginning I simply used the switch to keep that from happening when I didn't want it to. Once or twice I got into trouble and barely fought my way out. The spoilerons kill (or spoil) lift, which is not what you need when you are fighting for your life!
 
The one incident that spooked me was trying to take off with a 50% spoileron mix. I had forgotten I had the mix on, and the plane was glued to the runway. I was taking off from the taxiway and crossing the runway, so I only had about 40 feet, and when the plane refused to lift up I drove it straight into the high grass. The plane covers that distance in about 2 seconds, so by the time I realized what I had done, I was simply screwed and had to ride it out. I ran off the runway and was lucky not to damage the plane, and it was not until a few years later that it occurred to me I was using too much mix for general flying.
 
So, I went into this hoping to find a happy medium. Naturally I wanted the mix to be effective, but I also wanted to turn it back a bit, with the goal of being able to use it for the entire time without having to flip it on and off all the time.


 
I found that 50% mix made takeoffs very long and difficult. It also made recovering from a stall take much more speed and power to the point that flying 3D you had to be extremely careful. Elevator drops were totally spectacular, though the plane would come down much faster because all the lift was being killed by the mix. Harrier was improved, but you had to carry the nose much higher and carry a lot more power because the plane was much more deeply stalled. In a parachute maneuver, the plane would rotate and then continue to fall at just about just about unabated speed.
 
This was all great fun, but you really had to stray on top of it. At 50% the mix simply worked too well. As time goes on I may or may not increase the mix as I become more adept at flying it, but for now I am using less.
 
 I wanted the plane to be a bit more docile and the mix to create more fun, so I started dialing it back, at first to 35% and that was still a bit much. I eventually settled on 25% because it felt good the first time I tried it. You could fly the plane and almost not even know it was on until you did an elevator drop or something. I could toss the plane around and fly out of trouble pretty easily, so that was the final piece I needed so I could leave the mix on.
 
Mix On
Once I started flying the plane at 25% mix, I just left it on all the time.  This way I could just fly the plane and not worry about if it was on or not. Instead of choosing when to use it, I just learned to use it for everything.
 
Elevator Drops
The most shocking thing the mix does is allow your to do an absolutely dead straight down elevator drop. You peg the elevator stick, stay off the ailerons and steer it with the rudder, and it looks like a spider dropping down it's own web, or a brick falling down an elevator shaft. With the reduced mix, the plane falls a little faster than with no mix, but you can easily arrest that with a bit of throttle. As far as what you do to fly this move, is really no different from not using the mix, except you have to carry more throttle nearer the ground (ground effect really sucks the plane in using the mix) and you have to be more overhead because the plane won't travel forward much. Most elevator drops are on a bit of an angle, but with the mix it is like it falls out of the air, only slower. This is simply good, safe fun. You start off high and if you get into trouble, punch out with throttle.
 
Harrier Flight
This is one of the most delightful parts of the mix. The mix will spoil lift, and now the plane will balloon less in a harrier. In fact, now when you pull the nose up the plane will sink instead, and this requires more throttle. With the lift on the wing being spoiled, it has to come from somewhere if you want to stay out of the ground, and all that's left is the power. This is where a good, smooth and tractable power system like the Torque and Airboss comes in.
 
For harrier you do not necessarily need to haul the nose way up there, but it is certainly easier and more fun. You will see in the videos how high I can carry the nose, and there is a little less danger of stalling the plane since it is already very nearly there anyway.
 
I also like to use a turning harrier to lose altitude and line the plane up for a maneuver at the same time. With the ability to use less throttle and have the plane drop more, it's easier to do this with more precision. I just had to adapt my flying style a bit and carry more throttle until I wanted it to drop.
 
Essentially harriers become more spectacular, but also, with the wing more deeply stalled, this reduces any wing rock you get from sloppy flying. The mix simply smoothes harrier flight out like a stick of hot butter. Hey, if it makes me look better it must be good, right?
 
Parachutes
Here we are going to start getting a bit scary. For a parachutes maneuver,  you dive straight down, gain some speed, and then hammer the elevator back. This rotates the plane so hard that it is like sticking your hand out the car window flat (fingers pointed into the wind) and then turning it up like a cop stopping traffic. The plane will jolt to a near stop, and if you hold the controls it will settle into a nice, falling elevator drop.
 
With the mix on, this becomes a little different. With plane stalling during the rotating, and with the ailerons pointed up, it simply stops flying without bleeding off a lot of speed. The plane will fall belly first at high speed. At first this was very unsettling, that is, until I learned that you absolutely have to get on the throttle almost instantly, and this slows the descent.
 
The plane has downward momentum, and if you are brave you use the momentum to get closer to the ground in a bigger hurry, and then use the throttle to slow the elevator to a sane enough speed to set it down on the ground. I have done a couple of these successfully, but since we are dealing with high speed pointed that the ground, this is a maneuver you don't want to get wrong and I have sort of backed off on it.
 
Most saner pilots won't experience this much fear simply because they won't cut it nearly so close. Best bet is to try this at a higher altitude the first few times so you can judge the sink rate for yourself. Then you can determine how hard you want to push it, if at all.This is not a deadly maneuver, but it will be if you get it wrong pushing it too hard. It's just different and very spectacular.
 
It also helps a lot to be running Hitec's awesome new HS5087MH (which is the high voltage digital equivalent of the HS85MG) on the elevator. This assures solid elevator response when you are asking for critical performance. A low level high speed parachute is not a good time to experience stalling or blowback, and this servo assures you won't.
 
Thanks to my friends at Hitec who provided the servos for this plane. It's this kind of assistance that makes it possible for me to do more projects like this.
 
 
Tumbles, KE Spins, Pop Tops And Such
I purposely used the MXS wing tips on this plane to give me a little more stability with the mix on. When I chose this, I was being a little cautions, and now it turns out the tips hamper tumbling somewhat. I put up with this because I liked the stability, but I will take them off for the next video shoot. I expect snapping and tumbling to be much improved, plus I will be able to get it into the car assembled again!

  
This is still a bit of a work in progress. This mix does not seem to affect the plane that much in positive (inside) snaps, but it definitely intensifies outside snap rolls. this shows up most in a pop top when the Laser will merrily spin around. I think for positive moves a flaperon mix would work much better, and I will eventually get around to trying that too. I just did not want to confuse myself while I was learning how to use a spoileron mix.
 
With the MXS tips the Laser is a bit more difficult to knife edge spin, but this disappeared with the spoileron mix. Now the plane KE spins like an Edge EXP. It is almost effortless. With the tips the entry is ia little more critical, and I use and outside snap roll to enter it with a little momentum. Like this it's just a matter of holding the sticks in the same position every time and the tail lobs over the noise beautifully. Full throttle KE spins are very hard on the entire package, so now I try to do them, with as little throttle as possible, and this works really well with this package. I imagine without the tips the KE spins will be even more ridiculous, though right now they are still as good as I have ever seen.
 
Hovering
I am probably not the right guy to talk much about hovering because I am not happy with my ability there, but the mix seems to give me more control in a hover. The plane seems to lock right in. I noticed this especially running the mix on my 60" Yak, but the Laser seems to benefit here as well.

Precision
I am not so sure about this just yet. In slow and point rolls I have a bit of trouble keeping the plane on a straight line, but it can be done. I think the spoileron mix changes the stick timing because when I flip the mix off everything here goes back to normal. I hit a few good slow rolls with the mix on, but can do it much better and more often with the mix off

Landing
The plane will fall faster if you are trying to bring it in way nose high, but outside of that the only difference I noticed is that the plane is easier to land in rough wind. The 60" EXPs are especially light on their winds and big gusts can make them balloon a little. The spoileron mix kills lift, so that helps settle the plane down a bit when you are flaring out. The 60s wheel land so nice that I prefer that on calm days, but when it's gusty the mix comes in handy when trying to set her down.
 
In General
For just flying around much does not change with this mix. I left it on for my point and slow rolls and it seems fine. The only time you need to be a little careful is at slow speed because any elevator movement makes the spoiler effect come on. This is simply an adjustment to your flying style, which is what the pilot is supposed to be for anyway.
 
For now this is something that is jolly good fun to play with. I will probably keep the mix on the transmitter but will go back to using the switch and choosing when I want it on .... when I can remember, that is. Since my current transmitter will allow me to choose only spoilerons or flaperons, but not both, I plan to shoot a couple more spoileron videos and then try the flaperon mix.
 
I am sure that will probably be a fun project too.

Nailed
OK, you probably knew a disclaimer would be coming, so here it is: The spoileron mix changes the way the plane flies. This is both a good thing, but a potentially tricky thing. For example, you will be blown away by how fast the airplane continues to fall after a parachute, maybe to the point that you stand there with your mouth, open watching it all the way to the ground.
 
Don't be that guy. When using the mix plan you maneuvers a little better, set them up better and definitely use more altitude. With a little time you will adjust your flying and sometimes even forget it is on.
 
Some people are going to like this mix and others will prefer not to run it. I didn't like it when I tried it a few years ago, but this time instead of trying to adapt my flying too much I adapted the mix to suit me. Start off at 10% mix and then turn it up until you don't like it, then turn it back to where you did.