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Old Jul 20, 2012, 12:56 PM
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malden86's Avatar
San Antonio, TX.
Joined Feb 2009
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Thank for the reply Rich.
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Old Jul 27, 2012, 01:34 AM
La Mesa Air
La Mesa, CA
Joined Mar 2010
337 Posts
Hello my Skyfun friends,
I'm reposting this since I found the wrong thread before..
-------------------------
Hello people!
I didn't see a better thread to discuss the HK Skyfun Jet, and it looks like it was previously discussed in this thread. I figured I would share my setup and ask a question.

So I've got a few upgrades on my Skyfun as you can see in the pix.

Power:
Turnigy 2836 2350KV outrunner
6x4e APC pusher prop
Turnigy Sentry 60A ESC
Up to recently I've run a 3S2000, but now I'm running 4S2350 and 4S2800

Airframe:
Added carbon tube spars, each about 10", all gorilla glued in when I assembled the wings.
Balsa Elevons
Top mounted the servos and control horns
Hitec 65MG karbonite servos
Fixed landing gear - based on some eflite wheels and bent wire. I think the steerable nose wheel was a dubro kit or something.
Motor mount reinforced with a belly panel about 5" long. The actual metal mount on the top was drilled and tapped to accept #6-32 machine thread. The bottom panel is epoxied down giving a solid motor attachement.
Various other wood seen in the photos are more or less braces added after crashes to hold it all together.
Canopy is held on by a small dowel in the front, plus four magnets. None of the original plastic clips worked out of the box.

So with the 3S, I had measured by doppler about 80MPH. Last weekend I ran the 4S and borrowed a GPS logger, and got it up to 120MPH, although that includes slight dives.

One of my questions I've always had with this thing is where should CG be? Following the factory guidlines, the thing flew but was unstable, and lead to spins and high speed stalls. Now I have the CG pretty far forward. Currently I run it 2.5" back along the seam of wing and fuselage. That is about 1" in front of the root of the vertical stab. The way it flies now is a lot more manageable, but I always feel like I should be getting more elevon authority from it.

Anyhow, that's the rig. I'll have to get some video together for it soon.
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Old Jul 27, 2012, 07:52 AM
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idletime's Avatar
Canada, ON, Toronto
Joined Apr 2011
1,582 Posts
Well I'm super confused now about the Proper CG - which (if I'm not mistaken is supposed to be at the front of the finger holes).

But there is no way you that can happen if you mount the battery like kf6bbl has done (photo in above post) - way up at the front of the cockpit.

My battery would have to be placed directly in front of the ESC in his photo above - which barely fits as the canopy has no clearance at the back.

Where are other running the CG?
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Old Jul 27, 2012, 07:53 AM
Gravity sucks.
Australia, QLD, Toowoomba
Joined Mar 2011
562 Posts
Quote:
Originally Posted by kf6bbl View Post
Hello my Skyfun friends,
I'm reposting this since I found the wrong thread before..
-------------------------
Hello people!
I didn't see a better thread to discuss the HK Skyfun Jet, and it looks like it was previously discussed in this thread. I figured I would share my setup and ask a question.

So I've got a few upgrades on my Skyfun as you can see in the pix.

Power:
Turnigy 2836 2350KV outrunner
6x4e APC pusher prop
Turnigy Sentry 60A ESC
Up to recently I've run a 3S2000, but now I'm running 4S2350 and 4S2800

Airframe:
Added carbon tube spars, each about 10", all gorilla glued in when I assembled the wings.
Balsa Elevons
Top mounted the servos and control horns
Hitec 65MG karbonite servos
Fixed landing gear - based on some eflite wheels and bent wire. I think the steerable nose wheel was a dubro kit or something.
Motor mount reinforced with a belly panel about 5" long. The actual metal mount on the top was drilled and tapped to accept #6-32 machine thread. The bottom panel is epoxied down giving a solid motor attachement.
Various other wood seen in the photos are more or less braces added after crashes to hold it all together.
Canopy is held on by a small dowel in the front, plus four magnets. None of the original plastic clips worked out of the box.

So with the 3S, I had measured by doppler about 80MPH. Last weekend I ran the 4S and borrowed a GPS logger, and got it up to 120MPH, although that includes slight dives.

One of my questions I've always had with this thing is where should CG be? Following the factory guidlines, the thing flew but was unstable, and lead to spins and high speed stalls. Now I have the CG pretty far forward. Currently I run it 2.5" back along the seam of wing and fuselage. That is about 1" in front of the root of the vertical stab. The way it flies now is a lot more manageable, but I always feel like I should be getting more elevon authority from it.

Anyhow, that's the rig. I'll have to get some video together for it soon.
cg is located in the forward end of the finger holes - i put landing gear like you've pictured on mine, but couldn't get it off the ground because my back wheels were too far behind the CG - meaning the plane couldn't rotate for takeoff - so, try moving those back wheels forward (to just behind the finger grips), and balancing the CG at the finger grips underneath. - your configuration looks like it may work better if you swap the location of the battery with the front wheel/steering combination.
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Old Jul 27, 2012, 09:19 AM
ICrashRCs
United States, TN, Memphis
Joined Jun 2011
1,196 Posts
Quote:
Originally Posted by idletime View Post
Well I'm super confused now about the Proper CG - which (if I'm not mistaken is supposed to be at the front of the finger holes).

But there is no way you that can happen if you mount the battery like kf6bbl has done (photo in above post) - way up at the front of the cockpit.

My battery would have to be placed directly in front of the ESC in his photo above - which barely fits as the canopy has no clearance at the back.

Where are other running the CG?
I would say you're running a light motor?
Or the battery is too large...
Do what you have to do to balance torward the front of the finger holes.
The battery should be pretty far forward.
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Old Jul 28, 2012, 11:46 PM
Thailand
Joined Aug 2010
506 Posts
I am amazed that the manufacturers of many Chinese models go to all the effort and expense of making the moulds and then give little or no information on CG, surface throws etc etc. It makes me wonder if they ever get flight tested at all?
I have never had one so I am only commenting from observing the many SkyFun models at our flying field.
This is a very long running thread but is that because the model is so bad or so good? It seems to need endless modifications.
Jim
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Old Jul 28, 2012, 11:58 PM
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idletime's Avatar
Canada, ON, Toronto
Joined Apr 2011
1,582 Posts
Quote:
Originally Posted by IFlyRCs View Post
I would say you're running a light motor?
Or the battery is too large...
Do what you have to do to balance torward the front of the finger holes.
The battery should be pretty far forward.
Quote:
Originally Posted by Fox-composites View Post
I am amazed that the manufacturers of many Chinese models go to all the effort and expense of making the moulds and then give little or no information on CG, surface throws etc etc. It makes me wonder if they ever get flight tested at all?
I have never had one so I am only commenting from observing the many SkyFun models at our flying field.
This is a very long running thread but is that because the model is so bad or so good? It seems to need endless modifications.
Jim
Skyfun flies fantastically (IMHO) once you get the CG right.

I moved up from (1) 3S_2200 to (2) 3S_2200 in parallel at first because my older batteries could not provide enough juice - then I switched to 4S_2200 which is a much heavier battery. Flew it once and never seemed to get the CG right after that. Crashed on takeoff the next two times and is kinda totaled.

Deciding if to try to rebuild or order another one. Or build one from scratch like the Prime Jet8

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Old Jul 29, 2012, 01:00 AM
ICrashRCs
United States, TN, Memphis
Joined Jun 2011
1,196 Posts
You should have just gotten a better 3s or an 1800 4s.
To me that's a happy weight for this airframe in a rather go-fast config.
It also flys nicely on 1000 mah with a slower/lighter motor.
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Old Aug 06, 2012, 02:27 AM
Registered User
Joined Apr 2012
37 Posts
Motor Mount

Hi There.

I am looking to upgrade by Skyfun specs again. Using a HK 2836 3700 with 6x4 running at around 800W. Sensational fun but needs strong servos. Upgraded to a high C battery (3S) which made a big difference.

http://www.rcgroups.com/forums/showp...&postcount=786

Anyway, seems about the time to push the envelope again. I have a Turnigy H3126 Brushless outrunner 1300KV (1500W) with 6S to install.

http://www.hobbyking.com/hobbyking/s...dProduct=11182

I dont really want to custom build a motor mount. Does anyone know of an off the shelf large motor mount that might work?

Cheers
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Last edited by mgbolts; Aug 06, 2012 at 02:28 AM. Reason: grammar
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Old Aug 06, 2012, 04:26 PM
ICrashRCs
United States, TN, Memphis
Joined Jun 2011
1,196 Posts
I think it was in this thread a few pages back someone had put ply on the bottom and screwed through into the motor mount. That would add a lot of support.
Don't know of a commercial mount available.
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Old Aug 06, 2012, 08:11 PM
Registered User
Southern Darling Downs Qld, Australia
Joined Sep 2010
148 Posts
Perfect Skyfun 2836 Set Up.......3648 Mount Wanted,

Hi , i have had a Skyfun running Turnigy 2836, 2350 kv,60amp plush, 6x4 prop , 4s 40c 2200 mah lipo. and it seems to be the perfect set up ( i have strenghtened a few things) flys beautifully. The performance is almost the same as my Stryker Q so i have decided to fit the Skyfun with a Turnigy 3648 ,1400kv 1600w motor and 6s lipo.and bigger esc. just to see what happens I was wondering if anyone could suggest a suitable mounting for this motor ... is there a suitable after market universal mount available ? Cheers Ken
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Old Aug 07, 2012, 05:21 AM
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Joined Apr 2012
37 Posts
Motor Mount

I have used this one on my skyfun but its to small for the new motor.

http://www.hobbyking.com/hobbyking/s...43_42mm_.htmlo
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Old Aug 16, 2012, 03:12 PM
Registered User
The Netherlands, DR, Erica
Joined May 2012
10 Posts
Hi Guys i thought i jump in and tell you my current specs of the skyfun! After owning it for 2 years(first one which never crashed) ive had 4 upgrades.

After starting with a turnigy on 3s i quikly moved to 4s with a little larger motor.

Then a little bigger 3200kv motor on 4s.

And finally ik running a turnigy fandrive on 6s with a 200 amp esc, and its a beast!
Hitting 300km/h, it screams like a cat in heat!

Also ive got more then 3 meters of led lights for nightflying!(havent done that on 6s tho)

Im using small but very powerfull digital metalgeared servo's from hobbyking which have never let me down!

I always got my cg right in front of the 2 holes, (so not in them) and its always spot on

I love the plane and thinking of downgrading now to use it for fpv!
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Old Aug 16, 2012, 03:34 PM
Wats the worst that can happen
TheCure's Avatar
Canada, BC, Surrey
Joined Jan 2009
513 Posts
How do you launch your 300km/h Skyfun?


Quote:
Originally Posted by SilentStatic View Post
Hi Guys i thought i jump in and tell you my current specs of the skyfun! After owning it for 2 years(first one which never crashed) ive had 4 upgrades.

After starting with a turnigy on 3s i quikly moved to 4s with a little larger motor.

Then a little bigger 3200kv motor on 4s.

And finally ik running a turnigy fandrive on 6s with a 200 amp esc, and its a beast!
Hitting 300km/h, it screams like a cat in heat!

Also ive got more then 3 meters of led lights for nightflying!(havent done that on 6s tho)

Im using small but very powerfull digital metalgeared servo's from hobbyking which have never let me down!

I always got my cg right in front of the 2 holes, (so not in them) and its always spot on

I love the plane and thinking of downgrading now to use it for fpv!
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Old Aug 17, 2012, 09:08 AM
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United States, MI, Paw Paw
Joined Sep 2011
4,104 Posts
Man every time I check this thread I get upset that I ever sold my skyfun the mods and the creativity in here is just awesome. I think I might have to order another one of these as my "funfighters" have brought that speed twitch back
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