Skyfun Project

[JC1]

Just flew a new plane tonight, the FPV has been a great excuse for me to buy and test cheap Chinese foam airplanes.

I ordered 2 Skyfun aircraft from Hobbyking and they arrived about 1.5-2 weeks after the ordered cleared.

The Skyfun is a flying wing, which is a rip-off (theft of concept) from a few other designs, this is pretty common with Chinese aircraft

I bought the models for US $63.29 each.

The skyfun includes 2 servos, 1 1900kV brushless outrunner motor and an 18 amp speed controller. I was expecting it to be an unflyable, underpowered, piece of garbage. (If you set expectations low, you will never be disappointed, especially on cheap stuff)

Overview
The aircraft is not too terrible, it has a very smooth finish. In fact it is shiny aside from the injection points for the foam which are the normal injection marks.

The aircraft assembled VERY quickly. There are 2 wingtips which need to be installed and two vertical stabilizers. I used a fair amount of foam safe spread across the mating surfaces evenly instead of epoxy. Of course when gluing any surface, clean it well. I used 91% rubbing alcohol (also known as isopropyl, normal store stuff) to scrub the surfaces, then dried with a clean towel, then let air dry for a bit. (epoxy is included and may be better, but I used the foam safe CA)

Setup
I used an 1800mAh Li-Poly battery for this. Specifically a Turnigy 3s 11.1v 40-50C pack. (They're rated at 5c charge now!?)

For the receiver I installed an 8 channel Airtronics 2.4Ghz receiver. The Atx is no good for FPV, but it's fine for test/fun flights!

A simple re-configuration of the radio to delta and the setting of 35% exponential and I was finished building Monday night in about 1 hour for 1 plane.

Flight
My friend was busy working so I had to hand launch myself. It took a few tries to get it in the air, but I'm sure someone with experience would have no problem.

Although the motor seems very small, the plane has quite enough power to get up to a good cruising speed once in the air. While it is certainly not going to do unlimited verticals, etc. it flies pretty damn well in basic flight. The plane rolls like crazy and it loops fairly well. The loops could be tighter and rolls faster by setting greater control throw distance.

FPV Considerations
This plane has a large space under the canopy for avionics and OSDs and other things inside of it. The one thing I notice about the Chinese planes is that because they use a minimal amount of material to be cost efficient, there is a TON of space available inside of them. Sure the plane may not be as durable as another similar one, but we build planes to fly, not to crash!

The Plane is quite nose-heavy, to add FPV equipment into it would mean finding a way to mount much of the weight towards the rear. With just the receiver and the 1800mAh battery I still had to add $0.50 worth of coins to the back of the plane to balance. My planes are becomming my retirement account with how much money I have glued and taped onto them!

This is certainly a craft I want to do FPV on. I just don't know if people move their systems around often, or if they buy multiple systems?

Here are a couple of pictures (once the camera battery is charged):

   

   

[Grandcaravan]

What a great review, Jon!
Thanks for sharing your thoughts about this plane

Do you have a Key Chain Spy Cam? If yes, you could make a video for us, to see the flight characteristics. Is this possible?
In my opinion you have to install a bigger motor for fpv use.

Thanks and best regards
Heiko

[BlueAngel]

Mh, there is really much space in the front, but way too forward, so its almost useless.


What type of foam is it?
EPS
EPO

[Mr_B]

That does look like it needs a way bigger motor for fpv. I would be a screamer with something that can pull 40 amps and up. Would probably need a carbon spar then too I would imagine.

Mr_B
8)
//

[JC1]

Hi Heiko, no unfortunately I don't have the forward looking keychain cam, though I will look to get one. I do have a pack of gum cam though which I use for sideways looking video. I'll stick it on tonight if the weather is willing.

The wing already has slots in it for a spar, but alas none was included in the kit. Easy enough to buy and install though. The wings are actually very sturdy feeling even as they are, it is a hard foam and does not bend easily. The motor should be able to be upgraded but you would likely need to adapt the existing motor mount or make a new one. The built in motor is pretty small. I can get specs for the motor bolt pattern (spacing) later this evening as well as more detailed pics.

There are also some videos on Vimeo from one person who uses it for FPV.:
http://www.vimeo.com/8130116

[JC1]

Here are a bunch of photos of my SkyFun FPV setup in progress, I did a lot of work this evening and should finish it off on Saturday. I am going to add a servo for pan, but it will be controlled by a rheostat on the transmitter, not a head-tracker.

I replaced the stock motor and ESC (1800kv & 18 Amps) with the original motor and ESC from my Mini-Titan which was serving duty in a wing. The Mini-Titan motor is 3500kV and ESC is 40 amps. The SkyFun motor mount supported this size motor with no bolt pattern modifications, however I did have to grind down the lower arm of the motor mount to keep the outrunner from rubbing. Very minor work with a file... then dremel to make the work go faster.

               

With all the space inside of the SkyFun, I set up a Velcro breadboard of sorts. In the past I've used large pieces of Velcro on each component to
attach them.

   

With this setup I use a LOT of the loop material to make a breadboard base, and the components have small patches of hook material. They hold well and are easy to relocate.

           

This model has the barometric altimeter as well as the barometric airspeed indicator, some of the setup is shown in the photos.

   

I have also added a 'data port' to the model for downloading flight logs from the Eagle Tree eLogger v3 without having to dig in and find the data pins on the logger.

                   

Some various in progress photos

       

[Grandcaravan]

Looks extremely good!
I think, you now should have enough power

[clearskies]

wow love the velcro board!

[Mr_B]

Wow, Awesome, can't wait to see how this powers along...

Can't wait for some moving pictures from onboard

Mr_B
8)
//

[JC1]

Well some tech notes:

Velcro board = AWESOME!

JUNK PROP ON AWESOME MOTOR = lame.. exploded prop.

I took the plane out saturday with all the stuffs, was looking forward to it. It was pretty windy, but.. I was tired of sitting inside with an FPV plane so I went out with a friend.

NOTES:

5x4.5 Pitch prop on Mini-Titan (heli) stock motor adapted for Skyfun = EXPLODED PROP

Top speed before exploding your propeller: 26mph

Top current before exploding your propeller: around 65 amps (good thing the ESC is rate 40 amps.....? lol)

Data logging equipment = PRICELESS!!!

I almost gave up the hobby this weekend, the FPV plane broke into tons of pieces, just like the Catalina. I do not get it. I have lots of luck with normal GOOD quality planes (Twist 60 on 1.15 four stroke from hangar 9, Reactor Biplane, Mini-Titan heli, etc) and the junky chinese crap works okay without FPV.... Anytime I add FPV.... major problems, not related to RFI(the interference, not the battery brand )

30 Minute Epoxy + Microfiber filler = WHOO New(ish) (like new) aeroplane.

Unfortunately I'm very busy with a trade show project for the next week, so it will be a bit before the next trial. I have attached Eagle Tree log information. Action happens around 11:35, you can get the data logger software for free from Eagle Tree's website if interested.