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Old Oct 28, 2012, 04:35 AM
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davereap's Avatar
Ashford. Kent. England
Joined Feb 2005
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Originally Posted by lv2soar View Post
Hi I Am building a 36 inch Nutball. can anyone help with
what size servos I will need. I like Hitec Servos thanks
All depending on the flying weight ... My 36" was a KFm4 build and heavy ..30oz.. I used metal geared towerpro servos of about 14gms (MG9) and they were fine...for a smaller 20oz ball I used the same metal geared servos..but although I had no prolems with the small servos I used it might have been safer to use the 18gm towerpro MG16 on the bigger ball..
It more depends on the way you like to fly.. for mad aerobatics a stronger servo is safer..
The smaller standard 9gm plastic geared servos are not up to the job and will end up stripped
However as the big nutballs can cary a lot of extra weight, std servos can be used, if thats what you have handy
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Old Oct 28, 2012, 12:36 PM
repeat foam bender
ruddym's Avatar
Canada, ON, Ottawa
Joined Mar 2008
545 Posts
Quote:
Originally Posted by lv2soar View Post
Hi I Am building a 36 inch Nutball. can anyone help with
what size servos I will need. I like Hitec Servos thanks
HS-82 MG look like a pretty good option, and reasonably priced.
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Old Oct 28, 2012, 03:35 PM
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Los Angeles, CA
Joined Mar 2004
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Originally Posted by davereap View Post
well the weather here was poor yesterday.. so what do you do when your stuck inside with a big bundle of foam...
Yes I made another...This is a 30" all 6mm depron version.. Ive used a lot of the black depron here and increased the area to try and lower the wing loading .

Black depron is a lot lighter than white,and at the bigger sizes like this, it results in an overall saving of 2-2.5oz on the depron..
A 30" KFm4 nutball will be using 10sqft of foam..

For 6mm depron.....black is 0.5503ozsqft white is 0.8005ozsqft

For a bit of color I used white depron on the top which slightly lessened any saving, but looks better
Hi Dave

I am in the process of doing the split elevron mod
Do you have a drawing and dimension for the vertical stab and rudder assmebly or you just guess estimate it
Thank you
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Old Oct 28, 2012, 03:37 PM
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I R Irv's Avatar
United States, IL, Washington
Joined Nov 2008
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...

If you molded in an airfoil with dihedral what kind of thrust line would you give it? Also would any reflex in the elevator be needed?
TODD
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Old Oct 28, 2012, 04:44 PM
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Terry Rigden's Avatar
UK, Bedworth
Joined Apr 2004
2,813 Posts
Quote:
Originally Posted by lv2soar View Post
Which Hitec should I use? Thx
I've had great sucsess with Hitec hs55's on models up to 750 grams.

Terry
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Old Oct 28, 2012, 05:02 PM
repeat foam bender
ruddym's Avatar
Canada, ON, Ottawa
Joined Mar 2008
545 Posts
HS-55 is a good servo but there's no way I'd use it on a ~70 sq in control surface
A 36" Nutball is a pretty big plane.
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Old Oct 28, 2012, 05:06 PM
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Wingman26's Avatar
Oklahoma
Joined Aug 2008
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Originally Posted by ruddym View Post
HS-82 MG look like a pretty good option, and reasonably priced.
I've used the HS-81 with good results on planes where I wanted more power.
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Old Oct 28, 2012, 10:34 PM
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ruddym's Avatar
Canada, ON, Ottawa
Joined Mar 2008
545 Posts
Quote:
Originally Posted by lv2soar View Post
I am in the process of doing the split elevron mod
By splitting the elevator into elevons you're halving the largest control surface, so Wingman's HS-81 suggestion sounds good.
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Old Oct 29, 2012, 05:29 AM
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Ashford. Kent. England
Joined Feb 2005
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Quote:
Originally Posted by lv2soar View Post
Hi Dave

I am in the process of doing the split elevron mod
Do you have a drawing and dimension for the vertical stab and rudder assmebly or you just guess estimate it
Thank you
Its always a TLAR guestimate.. and Ive never had any problems.. I usually go a bit on the big size for any control surfaces, and get lots of movement...then downrate if its not needed and use expo..

simply splitting the elevator doesnt work well.. (especialy with the KF section giving more stability) the mod I made put in linked outer surfaces as well as a KFm4 wing section....as seen in the pic below.. that used one servo on each side with a double pushrod to work the two surfaces on each side... and it works well..giving ok inverted, ok hover and nice axial rolls...
note.... It still has a working rudder...the rudder pushrod is below the wing out of sight

why the KF... at the larger sizes it makes for a tougher stiffer wing.. I use a 3 layer KFm4 build.. then add tape for a strong model..
These larger sizes are more docile than the tiddlers, but are still highly maneuverable...
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Old Oct 29, 2012, 05:46 AM
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Los Angeles, CA
Joined Mar 2004
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Dave
Can you post a picture of the Rudder assembly also the top and bottom area
Thanks
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Old Oct 29, 2012, 06:35 AM
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Ashford. Kent. England
Joined Feb 2005
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do these help?
every shape ive used works fine for a rudder... there is a late addition of a CF rod to reinforce the fin.. when you chuck the model about the fin gets a lot of stress
The UC is on a ply plate velcro'd as seen
Pushrods have guide tubes every 2 or 3 inches for support.. this allows for a thinner dia. flexible and lighter rod

here is an old video.. you can see just how slow and docile the model can be flown and just how nice the rolls are. do note you can still power it up and fly as wild as you like..I prefer low slow and close..
.
Nutball KFm4 with elevons (6 min 55 sec)
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Old Oct 29, 2012, 11:24 AM
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Los Angeles, CA
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Thanks Dave the pictures are helpful. Can you give an idea what is the width and height of the rudder?
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Old Oct 29, 2012, 11:26 AM
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Los Angeles, CA
Joined Mar 2004
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Dave
I am building the 36" per instruction from here Post 2
And using the elevron mod from this thread. So it should work. Right?
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Old Oct 29, 2012, 11:54 AM
Lets break some props :D
joseico90's Avatar
United Kingdom, Liverpool
Joined Jun 2008
4,962 Posts
Quote:
Originally Posted by I R Irv View Post
If you molded in an airfoil with dihedral what kind of thrust line would you give it? Also would any reflex in the elevator be needed?
TODD

Now that looks nice indeed, I reckon the usual thrust lines would be fine 3 deg left 5 deg down, elevator reflex quite probably not needed.
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Old Oct 29, 2012, 04:31 PM
Re-Kitting Expert :o
Bullhead City, Arizona
Joined Jan 2005
1,689 Posts
Nutball Number 5

Here is my latest NutBall. A 24" er I built for flying outdoor. This one is built with 6mm Depron instead of the 3mm Depron I have used on the indoor planes. I started airbrushing this one while attending the Airbrush Getaway I just attended at the Tropicana in Las Vegas.




I took the Killer Skulls class, taught by Eddie Davis. It was awesome!
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