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Author Topic: Fun Cub-ery  (Read 935 times)

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Offline Deerslayer

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Fun Cub-ery
« on: September 14, 2015, 12:23:19 PM »
 The little Fun Cub is a great platform to try out things on, as it has full control surfaces, i.e., independent Aileron and Flap servos.  Not that this little bird really needs anything beyond plain vanilla setups, but you really owe it to yourself to tinker.

 I will describe a little set-up that I have. Why? Because it is a "Fun" Cub. It also is a good test bed on which to learn about Flight Modes, Throttle Curves and a bunch of other stuff. In fact, this setup is essentially what I am employing on 2 sailplanes. I use my Fun Cub as a sort of test bed because I can do gazillions of take-offs and landings with it in very short times and can learn things quickly that way. Note: I am using a Spektrum DX9, either in Airplane (for the Fun Cub) or Sailplane (for the V-ROC and Heron gliders); there are slight differences in the implementation but we achieve the same end result.

 I have a couple of Flight Modes set up: Normal is plain vanilla (yawn); TOGA (Take Off / Go Around) Flight Mode is the interesting one here, as it combines the actions of Throttle on a highly exponential Throttle Curve with Flaps + Spoilerons, all on the Left Stick. I can still retain coupling of Elevator-to-Flaps-and-Flaperons and/or Aileron-to-Flap coupling on the Right Stick , if I wish, either independent of, or dependent upon, any Flight Mode. There are many possibilities to play around with, overall.

So, what is this TOGA Flight Mode all about?

First, I set up a Throttle Curve which is invoked in this Flight Mode:

 The default Curve, which most people use without even examining, is linear. My TOGA-associated Curve is highly exponential (0,5,20,60,100). The lower half of the Left (Throttle) Stick travel only drives the Throttle Channel through a small percentage of its range, from zero rpm up to a fast Idle or so; the remainder of Stick travel is more linear, from perhaps 60% to 100% Throttle output. So, during a landing, the prop is usually serving as a speed brake; during a go-around, it is smoothly applying power. Nice ... so far. Or, I can simple flip Throttle Cut (Switch A) at any time to freeze the prop, e.g., during a glider landing where we want the prop to stop and fold before touchdown.

Next, comes the rest of the TOGA action:

 This Flight Mode couples the Flaps and Ailerons into the Throttle Stick to achieve variable Crow. NOTE: This is NOT the output of the Throttle Channel, just the Stick input to that channel; if you have the Throttle Cut applied, the motor is still disabled even while the stick is controlling  Crow. As the Throttle Stick is pulled back from, say, its half-way position, the Flaps progressively move down and the Alierons/Spoilerons rise. The result is Crow: A variably high Drag, decreased Lift configuration. All the while, you are still driving the aircraft normally, i.e., the Elevator has full control of Pitch.

 Those are the basics! How do you use it?

 So, as you swoop in for a landing or touch-and-go, you can go into TOGA Flight Mode at any time. As you pull back on the Throttle Stick, you are going to start dropping really quickly. Note: This may vary, depending upon the aircraft, e.g., on my sailplanes, I have to push Down Elevator quite a bit before they achieve the considerably reduced L/D while still holding low airspeed.

 Use your Elevator to maintain a suitable Pitch angle, play the Throttle/Crow as you wish. To abort the landing or simply touch-and-go, just nail the Throttle and the aircraft is automatically cleaned up and you are climbing. You can just leave the Flight Mode alone if you wish; provided you are flying at reasonably high Throttle, the Flaps and Ailerons mixing is no longer invoked - the aircraft cleans itself up and climbs out.

 If you do this, you lose nothing. You can, like me, still have available things like Elevator-to-Flaperon/Flap mixing, switch-selectable, whereby Up Elevator couples in some degree of Down Flap and Ailerons(Flaperons), enabling some wicked climb-outs or short take-offs from floats, or whatever else you have in mind.

 These radio systems have an incredible amount of capability. It is a bit intimidating. However, when you delve into it a bit, you will find that there is an awful lot of untapped Fun bottled up inside.

 If this lengthy discussion in any way intrigues you, I would be glad to try to help you try out some of this stuff on an aircraft. I may not know much, but what I do know is freely offered. :D


Aside: TOGA = Take Off / Go Around, a term familiar to those who fly bizjets, some airliners, etc. The idea is that a whole lot of stuff can/must happen quickly and precisely during a short and critical time when an aircraft drastically alters its configuration, power settings and resultant flying characteristics while the Pilot is busy on the "stick".
« Last Edit: September 14, 2017, 08:07:23 AM by Deerslayer »
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Offline Deerslayer

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Fun Cub-ery - an update
« Reply #1 on: February 06, 2016, 06:39:30 AM »
If anyone who has a DX9 or similar radio wishes to try this on their Fun Cub or any other plane, I would be happy to pass along my  .SPM file. There is no risk in this, as you simply bind a plane to this model configuration and you should not have to make any significant changes to try it out. I can help you to understand the setup and to try it out.
By now, I have many hours of use with this technique on a couple of sailplanes, the Fun Cub and, with variations, on other flapped and non-flapped aircraft (your 6-channel radio is just fine for that). What about on a Turnbuckle or one of its variants? Definately, as one friend is finding out on  his Minibuckle. 
My purpose in Life is to serve as a Warning to others