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Old Jul 19, 2012, 06:41 PM
Retired Engineer
St. Augustine, Florida
Joined Sep 2006
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Cox Sky Cruiser / Nine Eagles Sky Runner Mod Thread, SpekTrum, B-Less & Ailerons

I am the proud owner of a new Cox Sky Cruiser. However as with all my Cox and Nine Eagles Micro Planes I am starting the upgrade to Brusless Motor, Spektrum Radio and adding ailerons.

I will post my Progress here. Let us all show our mods to this plane in this thread. I will post it as I progress, sorry are I have just started and find it easier to post as I go rather than at the end as I always miss something. To start things off I will show the Aileron Servo installation. I have already removed the stock motor, wiring and Receiver. (They are up for sale in the General Radio Equipment section along with the Transmitter)

Here: http://www.rcgroups.com/forums/showthread.php?t=1694826

Here are photos of the wing Servo installation in one of the wings, I am using 2 Hobby King HK-5320 Ultra micro Servos.

1) Select where you want to put your Aileron Servos in the Wing We installed ours dead on the CG line (35mm from the leading edge) The Center of the servo is aligned with the CG.

2) Mark the Servo outline with a marker and cut a hole for it. The servo depth is 6mm we used 2/3 of the depth that is 4mm from the win surface.

3) Cut a small slot 2mm in depth as shown in the photo. You will need to do the same for each wing.

This will not compromize the integrity or strength of the wing as the servo will be glued into the slot providing adequate if not better support. I have replaced the JST connectors with conventional JR connectors. There will be a small slot in the fuselage in each side at the leading edge of the wing where they will go into the receiver area and will be joined together with a short "Y" cable. You could hard wire them in to save a little weight but then you would not be able to remove the wings. Yor choice. I would rather have the extra small amount of weight. The Brushless motor will be stronger anyway and I will most like use a better prop.

The next step is to cut the Aileron itself out of the trailing edge of the wing. I am currently working the sizes out but will probably be 2/3 of the wing length as is usual for gliders.
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Last edited by ShokWaveRider; Jul 21, 2012 at 11:34 AM.
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Old Jul 20, 2012, 05:32 AM
semper mitis
gentle ben's Avatar
Paducah, Kentucky
Joined Nov 2004
983 Posts
Interesting project. Still looking forward to your motor, prop, and battery selections.
I'm assuming you'll be using this reciever?:
http://www.hobbyking.com/hobbyking/s...Receiver_.html
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Last edited by gentle ben; Jul 20, 2012 at 05:40 AM.
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Old Jul 20, 2012, 07:04 AM
Retired Engineer
St. Augustine, Florida
Joined Sep 2006
1,212 Posts
Quote:
Originally Posted by gentle ben View Post
Interesting project. Still looking forward to your motor, prop, and battery selections.
I'm assuming you'll be using this reciever?:
http://www.hobbyking.com/hobbyking/s...Receiver_.html
No. This one: http://www.hobbyking.com/hobbyking/s...Receiver_.html

Battery Stock 250mah. Motor 1230 Brushless 4200kv, 7amp ESC. Worked on my Xttra 300's and Sky Rangers.
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Old Jul 20, 2012, 11:50 AM
semper mitis
gentle ben's Avatar
Paducah, Kentucky
Joined Nov 2004
983 Posts
I haven't used that reciever before. Will it work with your servo's connectors?
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Old Jul 20, 2012, 12:12 PM
Retired Engineer
St. Augustine, Florida
Joined Sep 2006
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Quote:
Originally Posted by gentle ben View Post
I haven't used that reciever before. Will it work with your servo's connectors?
I mentioned in the OP that I changed the connections for JR.
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Old Jul 20, 2012, 01:48 PM
Retired Engineer
St. Augustine, Florida
Joined Sep 2006
1,212 Posts
Today I added the Receiver, Rudder and Elevator Servos and control linkages. How this was done is as follows.

Servos:
1) Remove the metal ends from each of the servo control arms (Servo End NOT Control Surface End) Keep them as they are threaded and we will be using those for the Aileron Servos later. This involves removing the heat shrink and un-gluing the metal rods from the Carbon Rods.

2) Replace each of them with a straight 3" piece of regular 0.032" Piano wire, Glue and heat shrink in the exact same way and position as the ones you removed.

3) The next part is tricky as you will have to put a 90 Degree bend in each rod end, and depending on where you mount your 2 servos another 90 degree bend. This will give you enough room to mount your servos upright. Remember Measure2twice cut once. Then install whatever servo clevis pins you intend to use. I simply used the 90 degree Retainer Style as in the photo. Your measurements will differ according to your installation. All Adjustments will be made at the control surface end.

This method enables you to mount the servos upright.

Receiver:

This part was very easy, simply use double sided tape to stick the HK-R410 Reciver in place in the position shown, Tuck the Antenna into the ready made slot in the Fuselage and you are done.
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Last edited by ShokWaveRider; Jul 20, 2012 at 02:41 PM.
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Old Jul 21, 2012, 11:22 AM
Retired Engineer
St. Augustine, Florida
Joined Sep 2006
1,212 Posts
ESC Installed and Ailerons Cut. These photos are pretty self explanatory.
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Old Jul 22, 2012, 01:16 AM
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Joined Mar 2012
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Quote:
Originally Posted by ShokWaveRider View Post
ESC Installed and Ailerons Cut. These photos are pretty self explanatory.
ShockWaveRider...........
By the looks of your mods.......you are probably a very experienced
flyer. However if you haven't flown your sky cruiser yet, expect to
encounter execive pitchover with any throttle application. With the
Extremely high thrust line (twice as high as an easy star glider) there
Is inceficent incidence built into the stabilizer to prevent pitch over
Without a lot of up trim and elevator. Had the same problem with
my Cruiser........the fix.....set the TRX trim indicaor to neutral ,
Bias the elevator 1/6 to 3/32 up with the adjustable clevise, test
Glide and ad weight to the nose to accommodate the increased
Angle of incidence........it will fly as nice as the easy star glider.
Your going to like it.............just a Heads up. D.R.
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Old Jul 22, 2012, 08:58 AM
Retired Engineer
St. Augustine, Florida
Joined Sep 2006
1,212 Posts
Quote:
Originally Posted by Dutch rudder View Post
ShockWaveRider...........
By the looks of your mods.......you are probably a very experienced
flyer. However if you haven't flown your sky cruiser yet, expect to
encounter execive pitchover with any throttle application. With the
Extremely high thrust line (twice as high as an easy star glider) there
Is inceficent incidence built into the stabilizer to prevent pitch over
Without a lot of up trim and elevator. Had the same problem with
my Cruiser........the fix.....set the TRX trim indicaor to neutral ,
Bias the elevator 1/6 to 3/32 up with the adjustable clevise, test
Glide and ad weight to the nose to accommodate the increased
Angle of incidence........it will fly as nice as the easy star glider.
Your going to like it.............just a Heads up. D.R.
Thanks good info, I have not flown it yet of course even in it's standard form.
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Old Jul 23, 2012, 12:01 PM
Retired Engineer
St. Augustine, Florida
Joined Sep 2006
1,212 Posts
Aileron Servo & "Y" Splitter Installed

Here are some pics of the Aileron Servo Splitter and the Left Aileron Servo Wire Connected as it will appear in the Final configuration. In Addition I have included the Aileron Control using the threaded wire we repurposed from the Rudder/Elevator control rods. As you can see it is easy to do these mods without affecting the looks of the original Airframe.
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Last edited by ShokWaveRider; Jul 23, 2012 at 12:59 PM.
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Old Jul 24, 2012, 04:14 PM
Retired Engineer
St. Augustine, Florida
Joined Sep 2006
1,212 Posts
Here is the motor I will be using. It is the same as the HK-1230 4200kv. Fits right in the original motor mount. Have been using it in the Cox Xtra 300, there is pleny of power.

B1230 KV4100 EMP
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Old Jul 25, 2012, 09:25 AM
Retired Engineer
St. Augustine, Florida
Joined Sep 2006
1,212 Posts
Motor Added.

Added The 1230 4100kv Motor.
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Old Jul 26, 2012, 01:29 PM
Retired Engineer
St. Augustine, Florida
Joined Sep 2006
1,212 Posts
Prop Modification

I decided (While I was waiting for other parts) to modify the fuselage to accept a variety of propellers up to the GWS 5030, so up to 5". This required a fuse mod that would DEFINATELY compromize integrity unless reinforced as it was not designed for props larger than 4". I constructed a strong (stronger than the original foam anyway) Balsa and Ply insert. It will be painted white later on. The photos show what I did.
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Old Jul 26, 2012, 02:48 PM
Registered User
Joined Mar 2012
21 Posts
Sky Cruiser
Long Horn Conversion

1: two sets of wings required
2: cut one set of wings off 3" outboard of the wing root
3: cut the other set of wings off at the wing root
4: line up the leading edge and top airfoil, glue with C.A.
5: lay a strip of white 2" wide scotch brand packaging tape
(the one withe ribbed/fiber reinforcing) and lay on the under
side of each wing. Works good. Lasts a long time.

This mod is not labor intensive. About 7 minute per wing.....
The only thing a little time consuming is fabricating a
Miter box to make dead true cuts.

The result is a wing set that has the same aspect ratio as the
easy glider pro, and gives the Cruiser a beautiful sailplane
"look". 25% increase in wing area and a corresponding
decreasing wing loading. Flys as nice as it looks.
Unfortunately the closest thing I have to a computer is this IPhone,
and this fourm does not allow cut and past for photos.
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Old Jul 27, 2012, 01:44 PM
Proud of Brushless Sprouts
Commander Clumsy's Avatar
Belgium, Flanders, Antwerp
Joined Feb 2007
332 Posts
Finally a thread about modding the "big" Nine Eagles planes!
ShokWaveRider: maybe you could change the topic title, as the boards/motors/props/batteries are basically all the same?

I have the Cessna and Extra 300 myself and I must say that I am really happy with them after a few mods.

Cessna:
- Fibreglass reinforced tape under the wing to prevent wing flex
- Rudder enlarged by 2cm with clear tape - snap roll!
- Elevator should be enlarged with another 1cm as well to get it even snapier!
- The provided motor is ok for indoor, but the motor from the Extra (N60) is even better, the board takes it without any problem
- Removed the motor mount and "glued" that N60 motor back in with dubble sided 2-3mm insulation tape - crash proof plane!
- The standard snap-off props are worthless because of always hugely out off balance, I replace them for a GWS 4025
- 2S 300mAh (22 grams) to balance out the CoG issue, about 8-10 minutes flight time full throttle, cold motor

Extra 300:
- Same as above, except for the rudder/elevator mods
- The Extra also needs a less rigid connection between the front of the wing and the fuselage to prevent the fuse breaking in two after a heavy nose in (don't ask how I know) maybe something with rubber bands instead of a screw?

Happy camper here, let's hear these mods!
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