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Old Nov 25, 2005, 03:38 AM
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BBCC2 Guillows Super Cub 24" - 2 or 3 servos ??

Was searching this forum for a while now, came back with this Guillows 24" Piper Super Cub the other day, started the build largely inspired by some experiences described here.

As the pic shows I would be ready to start with the RC setup, LPS motor, Etec 2S1P 450mah, counting 3 servos (ail/rud/elev.) all the elements come to 110 g (Exc. covering, windshield, wheels, finish.)

Covering will be made with Graupner Ecospan, wheels incl. tailwheel are planned in bluefoam (3-4 grs incl. wires)

Found some Guillows Cubs in progress but not finished.... flying ?

Maybe some advice ??

Thanks

Rawy

This dusty project is kindly accepted in the BBCC2 Contest
http://www.rcgroups.com/forums/showthread.php?t=1842080

rawy
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Last edited by rawy; Mar 29, 2013 at 10:24 AM. Reason: new title - Second Balsa Builders Conversion Contest
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Old Nov 25, 2005, 11:03 AM
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2 Servos are in there !

The question was if it would not dramatically influence the flight abilities adding the weight of a 3rd servo, I was a post fm Warren Jones where he describes a mixing of ailerons with rudder but i'm dreaming of "glissade finals" like on the fullscale cub owned by a buddy

I could save the job and weight if an experienced Guillows builder & flyer out there could tell me more about the flying & approx. AUW !

read in one thread that a 24" Guillows should be below 180 grs. which seems
haevy to me already ?
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Old Nov 25, 2005, 04:00 PM
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nice build.
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Old Nov 25, 2005, 05:03 PM
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Hi Rawy,

Looks like a very nice cub you have there!

I would personally keep it with 2 servos, and maybe even drop down to a 250mAh pack. I did my Guillows Fairchild 24 like that.

http://www.rcgroups.com/forums/showt...8&page=9&pp=10

http://www.virtualaerodrome.com/hang...32&p_user_id=1

Flies very nicely, but keeping that weight down is the #1 thing it seemed to me. I think mine came out at 96g. Control authority is still very good with rudder, but no ailerons.

Cheers, good luck with your cub.

-James.
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Old Nov 25, 2005, 10:23 PM
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Nice Job Rawy,
Keep the pictures coming. I agree with James, go with the 250mah pack, you will save about 12 grams, a lot for this plane. Of course if you are using that motor direct drive then it will fly with the 450mah and the 3rd servo, it will just be fast.
Matt
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Old Nov 25, 2005, 11:43 PM
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i built this plane for free flight rubber band. i had all intentions to convert it to Eflight. if i was to do it over i would :
1. remove every other wing rib.
2. renenforce the cowel area.
3. make laminated tail feathers (it's going to be tail heavy if i don't)

i covered mine with coverlite. it added less than nothing to the AUW.
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Old Nov 26, 2005, 02:13 AM
Go get them Meg!
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If you can squeeze the extra servo in without too much weight, why not?

Cubs don't have a lot of dihedral (None), so unless you add some in a la freeflight like Sgt Dirt did, rudder only may be a problem.

That kit is a great one, BTW. I've lost two of them thermaling OOS in freeflight. Nice build.
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Old Nov 26, 2005, 02:55 AM
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James & Matt, I agree with the 250mah Lipo(9 grs), there's other 10-12 grs I should be able to remove cutting all the excess lenths in wires...removing the receivers case !
It always seemed easyer for me to gain weight on the hardware than slicing balsa, anyway I decided to remove every fraction excess weight.

Sgtdirt, the tailfeathers are very light already, 1gr for the rudder, 2.6 grs the stab before covering.

Irsudog, it's exactly what I was thinking at, if there is a way to fly it with scale dihedral (none?), keeping the weight in a range that allows correct flying abilities, I go for the ailerons solution.

Ideas for a light aileron linkage ??

Will post some pics tonight, made a weight check last night 114 grs before the above mentionned mods, could end up under 100grs...!
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Old Nov 26, 2005, 09:08 AM
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2 hours for 1,1g


but I must agree it is nice to build with balsa !

Started carving the wings out between the ribs, long job but gained 1 gr.

the small slots on the rudder 0,1 gr.

Still could not decide the ailerons linkage, would like to go for carb torque rods
(or should I say: I do no want to go for the metal wire ?)
the other aspect is that the cockpit is empty now & I wouldn't like to have this visible servo atop of it

Pull-pull ? what hinges ? how do you hinge with torque rods ' other systems ??

rawy
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Old Nov 26, 2005, 10:02 AM
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very nice sanding job. how about tape hinges.
you may be able to cram the servo above the window and into the wing and make your linkage go from there.
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Old Nov 26, 2005, 12:18 PM
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Rawy,

Great build, very nice airframe!

You could probably hide the aileron servo in the wing center above the cabin. There are some really small, light servos available nowadays, so the weight penalty shouldn't be that great. It would be a shame to fly a beautiful Cub like that without ailerons. You can just do so much more with them, as you well know by your mention of the "glissade finals".

I agree with you about using cf torque rods, although I would use some very small cf tubing, it's lighter and stiffer in torsion than the rods.

As for hinges, I would either use small ca hinges or preferably cut down the smallest plastic hinges you can find.

AmpAce
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Old Nov 27, 2005, 05:54 PM
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aileron hinges & linkage

Hi all,
thanks SgtDirt & Ampace, photos do not show everything & the so often mentioned quality of guillows balsa reveals with nice cracks when sanding the fuselage...
Did the aileron cutout, the cut or hinge line is not strait mmmhhh !!!

Will go this way http://www.rcgroups.com/forums/showp...&postcount=230

Concerning the linkage I'm almost convinced to go...pull-pull...
Was thinking about a linkage going thru the wings with a wooden spring returning to neutral or slightly down in case of trouble, a secondary loop arranged in the cockpit in order to place the 3rd sevro in the lower quart of cabin under pilots seat...theres plenty of ideas coming sanding balsa...

The servo placement under the wing in the upper back of the cabin does not attract me because in flight you always have this servo in sight mmmhh !!

the reason why I do not like the piano wire/plastic tube system is because of the short cord will result in a very short radius in the wing which in my opinion is too much energy & weight for an ugly result (steep angle toward horn)

Fullscale has pull-pull - lets study pull-pull
will have to study my geometry books once more,

Sadly have to put this little bird away for two weeks due to work, the photos of the actual progress are not so good, will post some more early next week.

Would enjoy to have some posts about "wired" aileron experience & I wish all of you a good start into December !
rawy
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Old Nov 27, 2005, 06:23 PM
Go get them Meg!
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The lightest and most trouble free aileron linkage would be the Dubro (catalog #850) micro torque rod aileron system. You might have to substitute a bit longer wire instead of the supplied torque rods (Because the Cub's ailerons are pretty far out on the span) but it comes with everything you need for around 4 bucks. For a light plane, this is perfectly adequate.

The aileron servo would be mounted upside down between the wings, with the linkage inside the cabin. Might be a little tricky since you cabin is already built, but it would only add maybe 3-5 grams to the plane, plus the servo of course.

*edit* After looking again at you structure pix, the aileron servo could easily be mounted behind the wing, and would be hidden once the Cub is covered.
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Old Nov 28, 2005, 01:59 PM
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pull - pull

There's some sanding to do again, will have time to think about where to hide that servo...

A lower servo position would allow to gain weight again, reducing the cable lenght..,I plan to solder the cables on the receiver, remove the case etc.
Was watching James video again and got haevily motivated to go
l i g h t

Basically I love the pull-pull complications...all my builds have p-p tailfeather linkage mostly modified from the plan, sometimes hidden in the fuselage (Beaver), or double rudder (K+WC36) on pull-pull thru center of fuse with cf rods to rudders.

But never made pull-pull ailerons & the aspect of ailerons trouble in flight makes one allergic to fuzzy systems

there's some sanding to do again...
rawy
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Old Nov 28, 2005, 02:31 PM
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Gasp, MY video? I'm honoured!

Looking forwards to seeing yours take to the air.

-James.
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