"The Sixth" is [completed] - RC Groups
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Nov 08, 2009, 02:08 PM
Syberian's Avatar

"The Sixth" is [completed]

My name is Oleg. I am from Russia.
I want to share my first SPAD project and set up some questions.
Briefly, it will be a huge Piper Cub with 2.4m (94'') wingspan all made from coroplast. The engine is planned RCG 26cc gas.
The main goal is to settle some FPV stuff and having many exciting views of over-cloud flight

Wings have a "Clark Z" profile with spar and ribs. Total weight is expected up to 6-8 kg.
There are no plans other than scaled "Clark Z" footprint.

Here are my questions:
- how much servos should I place on the wings? and what torque is required to drive the aileron of such size?
- should I enforce the tail side of fuselage with aluminium ribs, or it will be sufficient to glue together coroplast plates?

Here are some photos of current state:
Last edited by Syberian; Mar 21, 2010 at 07:00 AM.
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Nov 08, 2009, 07:12 PM
Registered User
earlwb's Avatar
On the big 3D aerobatic planes, they typically run three aileron servos for each aileron and dual elevator servos (one for each elevator half). The three aileron servos prevent twisting under load when flying. otherwise the aileron only works around where the control arm is hooked up.

So I would run three aileron servos, one near each end and one in the middle of the aileron on each wing. Since you have more than one servo on the aileron the standard size servos should work fine. These are the servos that weigh around 55 grams each. You can simulate the air loading on the ailerons by holding the inner section still and flexing the outer part to see if it flexes a lot or not.

Depending on how big your elevator halves are you could run two servos or larger ones if needed.

I don't think you need to gang or parallel servos together to run the control surfaces like they do on the bigger larger planes with 100cc engines et cetera. Your 26cc engine doesn't strain the plane anymore than running a 120 (20cc) size 2 cycle engine would.
Nov 08, 2009, 09:33 PM
Syberian's Avatar
the standard size servos should work fine
I have spotted that cheap standard servos with 10kg/cm torque. I consider what two of them per half-wing will suffice.
Thanks for your competent answer.

[many apologises for my poor English. i don`t use any automatic translators `cause they are cr*p]
Last edited by Syberian; Nov 08, 2009 at 09:40 PM.
Nov 08, 2009, 09:54 PM
Registered User
earlwb's Avatar
Those are pretty good servos, especially for their price. i bought quite a few of them, and have them installed in three airplanes. None of the servos has gone bad on me, they all have been working OK. Granted one can easily get better servos, but it is hard to beat the price. Plus they do work OK. So I have been satisfied with them. I use its sister servo with the plastic gears as throttle servos as well.
Nov 08, 2009, 11:18 PM
Syberian's Avatar
My friend bought a pair of them to remote control water valves in the bathroom
Nice idea for automatic temp control because of our traditional water temp leaps.
Nov 09, 2009, 12:26 AM
Registered User
BEX's Avatar
Hi Syberian.

The wing looks cool , but why the ribs?
I have built a sport tipe coro plane of same wingspan at 4 kg AUW , so it is possible to aim lighter.

I use 4 x standard servos on the wing.
Nov 09, 2009, 12:51 AM
Syberian's Avatar
but why the ribs?
The ribs are needed to maintain the right airfoil shape. Also they makes the wing very hard to bent and axial twist.
The overall weight of both consoles is 1200g (2.65 lbs).
I wonder how the single-spar wing could resist to flutter and twists?
Nov 09, 2009, 03:43 AM
Registered User
Oleg, Very nice plane.. Are those Coro ribs? Let us know how she progresses. Video would be nice.
Nov 09, 2009, 04:07 AM
Syberian's Avatar
Are those Coro ribs?
Exactly. 3-mm thick.
It cuts easily with paper knife, glues with thermal pistol...
Nov 09, 2009, 08:51 AM
Registered User
BEX's Avatar
Single spar wings of that ize is no problem , i just ad a dowel in the TE to keep 2 winghalves lined up when i do a take-down wing. Look at this thread http://spadworld.net/forum/viewtopic.php?t=16176
and this one http://spadworld.net/forum/viewtopic.php?t=15869

I am busy building a 3m glider wing at the moment , 3 part takedown.
Nov 10, 2009, 11:36 AM
Syberian's Avatar
Hi all
Today I found the topic here, where was discussed the downtime of the famous STTB site.
To prevent any loss of such a unique information source, I was dare to archive all the SPAD section of that site.

Here are my backup in single-file .chm format (128 MB) - opened with simple doubleclick

If there are any copyright infringement, please notify me immediately to remove this link
Nov 14, 2009, 07:12 AM
Syberian's Avatar
Today I`m hardly stucked. Yesterday I moved my coroplast wings to the balcony (-20C). So they are deeply frozen and thermal glue breaks like a glass! I split the side rib by lightly pressing it with my finger.
What glue can beat the thermal glue and withstand the frost? Please help me.


Well... I splitted the wings to the components as there was no glueing at all. Will try soldering iron welding technique by piercing the holes in the materials.
Last edited by Syberian; Nov 14, 2009 at 03:12 PM.
Nov 14, 2009, 03:45 PM
Registered User
Siberian, I think CA is better than hot glue for cold weather flying. If you don't find CA you could use hot glue and add a few staples to the seam. Even zip-ties would help keep the wing together. You could sew the seam with monofilement fishing line. My wife has a recipe for pelmeni that requires the chef to put the pelmeni on a tray and place them outside until they freeze. We've been waiting for months here in California for them to freeze. You're very fortunate to be in Siberia!
Nov 14, 2009, 04:02 PM
Registered User
Oleg, Go to www.vorona.org. The crow is an accomplished SPADER and cold weather flier. He lives in Ufa, Rossia. I think he would be a great help to you. Good luck..

Nov 15, 2009, 06:28 AM
Syberian's Avatar
Well, I`d prefer to keep my pelmeni among the cold beer in my large refrigerator located under my Hawaii isle villa Just a dreams.

I`m already wrote to the Crow about the coro a couple of weeks ago and don`t rcvd any reply yet.

I got a lighter torch and the soldering iron and spent all night experimenting with the coro.

I believe now the welding is the best way to bond the coro plates together. Despite of thermometer readings.

UPD Just received an answer from crow.
Last edited by Syberian; Nov 15, 2009 at 09:53 AM.

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