Tailed Nutball Mod

Background/Overview

This is a mod for the FT Nutball design that changes little from a build perspective, but quite a bit in terms of flight characteristics. It changes the design from  tailless to tailed while still retaining the same RET control scheme, making the handling more predictable and easier for less experienced(and if set up correctly, even new)pilots. I had attempted myself(as a very new pilot before learning on a basic trainer) to build and fly a standard Nutball on a couple of different occasions, and both times the plane flew, but was erratic, uncontrollable, and dreadfully pitchy. I scratch built these just eyeballing the plans and they had slight imperfections, but they were still pretty much standard Nutballs.

I beleive with my experience now, I could get a stock Nutball to fly well and have some fun with it, but it would likely still be a somewhat challenging experience. I decided to experiment with tailed versions in an attempt to make the flight characteristics more docile and predictable, and more along the lines of a basic trainer, but still interesting for a more experienced pilot. Why? Because the Nutball design is extremely easy to build, has ridiculously low wing loading, and has a unique a cool and eye-catching shape. These are all things that make it very attractive to newer pilots, who are then usually overwhelmed by the plane's sensitive responses  and somewhat extreme aerobatics. My experiments and approach to making a more beginner friendly version of the Nutball were very successful, and I'm very statisfied with the tail mod for this purpose.

Difficulty

Build: 1/5; as simple as it gets.

Fly: 1-1.5/5; based on build, scale, and parts choice, it is possible to make this design about as easy to fly as any basic trainer.

How To

A tailplane is added. The main wing and tailplane can be cut as one piece if desired. Size and shape of surfaces to preference, with the elevator now being located on the tailplane rather than the main wing. The elevator will be moved to the tailplane. The main wing is now free from control surfaces, so a full wing dihedral or double dihedral can now be applied, or alternatively, the dihedrals can be left as they are on a stock Nutball. Experimenting with different variations and degrees of wing and/or wingtip dihedral seems to be the main way to affect and customize the handling of this design further after adding the tailplane.I can't comment on the exact specifications of a perfect, standardized tailed Nutball, and there is a lot best left to individual preference. I am still prototyping different variations myself. I imagine an ideal version for training would be about a 19'' wingspan like the swappable series Nutball, and have a moderate but not extreme dihedral.

The CG(center of gravity) will more or less want to be about where it is on the original tailless design, so either some nose weight will have to be added, or the nose and battery area should be extended out past the leading edge, to compensate for the addition of the tailplane.

How It Works

The addition of the tailplane will add a ton of pitch stability to the inherently pitchy desgin of the round wing. The tailplane creates negative lift which adds a bit of nose down leveling force and stability to the ptich axis, and it also reduces the inherent size of the elevator somewhat. The original design's high alpha abilities also diminish significantly. The result is a plane with handling very close to that of a basic trainer, with a pinch of the original Nutball's high alpha ability, which makes stalls gentle and landings more forgiving in some respects. This plane can also maneuver and turn tighter than most trainers, making it ideal for more confined outdoor flying spaces.

Flying

A properly built and trimmed tailed Nutball will handle a lot like any basic straight wing RET trainer, with a touch of the agility, maneuverability, and high alpha inherent to the Nutball design.This plane can perform snap 180 turns and even snap 360's, which look sort of like a Tokyo drift combined with a quadcopter "funnel" maneuver.The tailed Nutball handles well at low and fairly high speeds, and anything in between. The plane can loop and flip, but not quite as effortlessly as some straight wing trainers. My observations may be due to using a full dihedraled wing on my designs, whereas I imagine a wing where only the tips or part of the wings were dihedral would be a bit more stable in such maneuvers. In flying areas where landing gear is not suitable(such as the rough desert lot I usually fly in),using a basic tractor prop setup, a pilot can perform a "flop landing", coming in at a high angle of attack and cutting all throttle before the nose hits the ground. This will be easier on the props and motor if done gently. 

Video

This is compiled footage of a very simple prototype in the mini size range. My plane has a 15.8" wingspan and 1806 motor running 5x3 props on 3s. I went with a fully dihedraled wing with a fairly shallow dihedral. I would not really recommend this small scale for a trainer or beginner plane, but it handles quite well. I have just begun to learn the most rudimentary basics of video editing(and have still not quite figured out how to fix or remove the incorrect time stamp on my camera), but I think this compilation captures the full capabilities of the tailed Nutball.

Closing

I personally think the Nutball is a great platform for all sorts of mixing, modding, and customization. I hope my tail mod idea will make it more approachable to less experienced pilots, and inspire others to do some tinkering of their own with this and other setups!