Report Overview
This report is going to be a little different, if not completely backwards. See, I've already had a 47" Vyper. It was a great little plane, and I loved it right up until I got stupid and wrecked it.
This report was being and published before my new Vyper had flown, but now that it has, you can read the flight report at The Vyper Strikes, Part II
The Tragedy Of Vyper #1
I was really excited about my Vyper. My background includes lots of competition precision aerobatics. This is what attracted me to 3DHS to begin with when I had my Aspera pattern plane. I loved that plane so much that I wanted more 3DHS planes, and that led me right into buying their 3D style planes, and learning 3D.
I have always loved graceful precision, and have learned to love 3D, so, I was pretty amped about the prospect of having a precision plane that flew like the Aspera, and with the flip of the rate switch could go right into crazed 3D antics. Best of both worlds, really, and what I have been looking for since I came back to the sport.
When I wrecked my first Vyper, I was so angry with myself that I threw the wreckage in the attic and moved on to the 42" Slick and 57" SC. Too many other nice planes to build and fly, but I have always known I would have another Vyper. I was just so angy with myself that I wanted to forget the whole mess.
This changed pretty quickly when my friend Steve got a Vyper and we set it up for sport. You can read about that here:
http://docaustinsfreakshow.blogspot.com/2010/01/sport-flying-3d-hobby-shop-vyper.html
Flying Steve's Vyper reminded me why I loved mine so much, and I ordered a new one as soon as I could get home that day.
Vyper #2 Strikes
Power Theory And management
My first Vyper was powered by the awesome Torque 2814 motor and Thunder Power 4s 2600 Pro Lite batteries. Like this it was an blindingly fast rocket, absolutely brutal, something which, at the time, impressed me greatly.
Lately, though, I've been cutting back on the power on all my planes, in exchange for lighter weight and a bigger prop. The benifits of lighter weight are obvious, though you have to fly the bigger prop to understand how that translates into more vectored thrust (and more control authority) in post stall Alpha flight. As long as you have a little power on, you maintain air, and control authority, flowing over the control surfaces.
Of course, dropping the voltage means you give up some power, but with 4s and the big motor the Vyper was seriously, wastefully, overpowered anyway. That and with less weight, you don't need all that extra power to haul it around. You simply don't need that much power for flying around at sub stall speeds. With big power, it might go 100mph, but that isn't what 3D is all about.
With lower power, throttle management is much, much easier. Before I was constantly working the throttle in a hover or harrier, and most of the time giving it too much and blasting out, but with the new set up, now I just set the throttle, leave it alone and fly the plane. The plane flies better and I fly better.
How this translates into the new Vyper set up is moving to the smaller and lighter Torque 2818 motor and Thunder Power 3s 2250 Pro Power batteries. This is much lighter than the big 2814 and bulkier 4s 2600 Pro Lite batteries. Also, by moving from an 11/5.5 prop to a 13/6.5, that's a full two extra inches of prop blast going over the control surfaces. In post stall flight, this is the holy grail.
CONTROL SET UP
I've noticed there is a formula to the set up of 3DHS planes. It's 27-30 degrees on aileron, and 45 degrees on elevator and rudder, with 75% exponential all the way around. On dedicated 3D planes, experienced 3D pilots run as much as 45 degrees on the ailerons, but the Vyper is a precision plane with a more efficent precision wing platform. It needs less aileron throw for roll control than a conventional 3D plane, so we are sticking to the 35 degree formula. The rest remains the same, including the low rates specified in the manual.
Ailerons
Here you can see we used the 3DHS phenolic servo arm extentions on the second hole out. With the end points maxxed we can get as much as 50 degrees of throw, but we backed it down to 35 degrees, at least until we fly it and figure out how much we really want. I'm pretty sure this will be about right because the first Vyper was perfect here. Still, tastes change when you grow as a pilot, and I might want more. That's why I left myself some room to crank the end points.
This is a very simple arrangement, made even easier now that I am using a seperate channel for each aileron. It's just a matter of using the sub trims to get the servos perfectly centered and avoiding unwanted differental. If I eventually want some differental, I can dial it in with the end point control. These new computer radios have made set up a little more complex to understand, but much more simple to execute.
Elevator
Again sticking to the formula, we shot for 45 degrees. The Vyper has a long tail movement, which makes it very pitch stable, but unfortuantely compromises pitch authority when compared to a short coupled dedicated 3D plane. To get around this we hinged this Vyper a little looser so we can get as much a 60 degrees of travel. We're starting with 45 degrees, but I am sure we will end up with a little more just to get the plane to rotate harder.
Again, we have 3DHS phenolic servo arm extentions on the second hole out, and end points dialed back to 125% to get the 45 degrees of travel. One departure here is the carbon rod glued over the metal pushrod. While not necessary, this stiffens up the whole assembly so much that there is no chance of any flexing at all, which is going to make the plane fly more precisely. The carbon tube costs next to nothing, and weights next to nothing, so if there is any improvement at all it will be more than worth it.
Besides, it looks cool.
Rudder
With the lighter batteries and motor we went with a rudder pull-pull cable set up to get the rudder servo out of the tail and closer to the CG. This not only makes balancing the plane easier, but moving the mass closer to the center makes the plane more agile. There is less mass to move on the ends, so the plane becomes much more responsive.
Again, 3DHS phenolic arms, only this time on the inner hole.
We could have gotten away using a stock Hi tech arm, but this one was already made up from the last Vyper. Using the sub trims to perfectly center the servo, with 140% end point control the throw is perfect both directions.
Center Of Gravity
Each individual plane is a little different, but I ended up with the CG right in the middle of the wing tube on my last Vyper. I was slowly moving the battery back, and never got it perfect before I wrecked it. With the new rudder set up, I've got plenty of room to move the battery back. Where it sits now, the CG is right on the wing tube, and since this worked so well on the first Vyper, this is where we will start.
EQUIPMENT INSTALLATION
Extreme Flight Torque 2818 Motor
The teriffic little Extreme Flight Torque 2818 has served me extremely (no pun) well in my 47" SHPs, Edge 540s, Yaks and Katanas. Most of that time has been howling on 4s, and even at that these motors have been impossible to kill. Most 3DHS planes are designed to accept Torque motors with no modifications needed. The blind nuts are pre installed, so all you do is simply bolt the motor on.
On 3s the 2818 was plenty of power on Steve's Vyper. Since I'll be using higher discharge Thunder Power 2250 30C Pro Power packs, I can expect a little more, so there won't be any shortage of grunt.
Extreme Flight Airboss Elite 45 Electronic Speed Controller
As always, we use nothing but Extreme Flight Airboss Elite speed controllers (ESC). For this plane we merely transferred over an Airboss 45 we had sitting on the shelf. This is a bit of a rarity because I always seem to be at least one Airboss 45 short. Of course, this year's unprecedented carnage has made some previously allocated equipment available, but that's not the best way to do it. I need to pick up a few more Airboss 45s so I'm not always robbing one plane to set another up..
I am especially fond of the Airboss 45 because it gives me the flexibility to run 3, 4 or 5s batteries. It also requires nothing more than simply plugging it in, and I like safe, bulletproof things that are easy to use. The Airboss 45 is just that. All you really need to do is check your amp draw and make sure you prop the motor to pull less than 45 amps, and you're good to go.
I've used the Airboss Elite 45 ESCs in all my 47" airplanes, and they have provided hours and hours of perfect reliability and smooth, consistent performance. I won't use anything else.
On my first Vyper I mounted the ESC on the side of the motorbox. This is the way I always do it, but the Vyper is a little different. The cowling fits much closer to the motorbox, so with the ESC wedged between them, there isn't a lot of room for cooling air to flow around the critical electrics. I didn't have any problems, even in the blistering Florida summer, but this time we went with mounting the ESC on the bottom of the motorbox.
This achieves a few things. First, the ESC is now mounted directly on the centerline of the plane. Before both the ESC and the elevator servo were on the left side of the plane, and that couldn't be very good for laterally balancing the plane. This way, it's in the middle, which just happens to put the ESC right behind the onrushing air coming through the immense cooling hole in the front of the cowling. In this location, it's going to get a heck of a lot more cooling air going over it, but I would have already known that if I had read the instructions the first time around.
Receiver Installation
By now most readers already know I am extremely obesessive about radio installation. Like on the first Vyper, I mounted the receiver below and to the rear or the battery tray. This not only puts the receiver right on the CG, but it is easy to work on without the battery, ESC wires, or rudder servo and pull cables getting in the way. With 3" extensions on the aileron servo wires, the ailerons plug straight into the receiver with very little slack. This keeps the wires from flopping over on top of the rudder servo where the arm could grab and unplug them. With the receiver mounted nice and low, it stays out of the way, and so does the antenna installation. In this picture there are a few loose wires, most notably the rudder servo wire, but I am still piddling and I'll wire tie off the slack when I am satisfied everything is as neat as I can make it.
Part of this is pride, but mostly it is because things that are done sloppy, fly sloppy...when they don't fail altogether, that is.
Battery Compartment
As you can see, by placing the ESC below the motorbox, all the wiring is outside the battery compartment. This allows you to slide the battery in and out without snagging it on any wayward spaghetti and maybe ripping out something unimportant like the switch wires or something. This is just another way you can avoid potential ptroblems later by making things as neat and tidy as possible now.
NEW TRICKS
Something I have never tried before has been running the ailerons on seperate channels. Not only is this useful for centering the servos with sub trim independantly, but it also opens up mixing in flaperons and spoilerons.
For now we are just experimenting with the flaperons which operate in the opposite direction of the elevator, expecting this to greatly increase pitch authority and decrease the amount of space you can turn the plane around it. For the first flight I will have it disabled, but subsequently I will have it on a switch so I can turn it on and off. We will see how this works out, but if it gives the plane more extreme capabilities....well, 3D is all about the extreme, isn't it?
NAIL
I think that pretty mucn covers putting the plane together. With this out of the way it's just a matter of dialing it all in and shooting some video. Of course there will be a flight report, and I have learned so much about alpha technique since my first Vyper that I think I can much better take advantage of the Vyper's hybrid abilities to go back and forth from precision to 3D Alpha flight.
While the first Vyper was fascinating, the first of any new airplane is always the most difficult, though few end so tragically, so soon. Having learned alot about the Vyper and it's set up the first time around, I expect this one will be much better sorted out from the first take off. All we have to worry about now is the pilot going stupid again.
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