I'm working on the ailerons for a 1/4 scale Sig Cub. The 1/4x1/2 wood used to fill in between the top and bottom surface seams heavy. Has anyone cut holes in this area to reduce the weight?

I think it was a design intent to have that heavy (and strong) of wood so as to deal with the flight loads that the ailerons would be subject too. Cutting lightening holes in it would only weaken the structure. Given the 1600 square inches of wing surface for an airplane that weights 14 to 16 pounds when completed, I would think that the weight savings from cutting the lightening holes to be insignificant.

Cheers,

Good point.

Hey Steve,

Post pictures of your build!!! Everyone likes to see stuff like that and judging by the pictures shared thus far, you appear to be a master builder. Very nice work...


Cheers,

Here you go. Has anyone done split elevator with two servos on this plane? I don't like the way its joined.

I set up pull-pull on both elevator and rudder on mine, makes using a split elevator easy if that is what you want.

If it were me, I'd use the pull - pull cable solution as well. Makes for some difficult time getting the rigging right where both elevators track the same. But with patience it can be done. An alternative would be to drill through the dowel into the balsa, which joins the two elevator halves together with a 1/16" bit and go deep enough to allow a couple of tooth picks to be pushed through the dowel and into the balsa. This adds a great deal of strength in that joint when glued with thin CA.

I joined my elevators as per the plans and have had no issues, best flying plane I own.
Anthony

Does anyone have some pictures of the pull - pull cable system?

In the last 10 years I have built ,flown and sold three of these and the fouth is framed and ready for covering. If you follow the plans these build strong and durable . The light wing loading means you dont have to try to reduce the weight. The only failures on these planes that I have seen is the failure to follow instructions . If you try to save weight in the wrong areas you will weaken the design . I have hovered , rolled , snapped and spun and never had a weight concern or a failure . This is probably the only plane I have built so many of and found no need to change the plans (other than servo locations and firewall position due to engine choices ). I guess what I am saying is if you change the design use caution , but dont be affraid of the design as it is.

CK1
Its good to hear these fly so good. The only reason I'm looking at changing the elevator is the one side broke off (the side without the hardwood). I glued it back on and it looks to be OK (as you can see in the picture) but I would like some extra support. So I'm looking for options.

I would either put another piece of ply as it was done on the right side, or drill the hardwood dowel and pin it with toothpicks. I've done that on several airplanes with good success and a good deal of strength added. Keep things simple...

Cheers,

Drilling and pinning is a good option. My son has a Super Sportster (big one) and it has two servos on a split elevator. Its a nice setup. I just finished a TH Kaos ARF and it has a split elevator with two push rods on one servo also a nice working setup. I don't think the one servo two rod setup is suited for this plane but it got me thinking about options for the cub.

Ditto, a pull-pull is really overkill IMHO. If you want to pin them, go right ahead if it makes you more comfortable.

But this is a great flying plan as is, there's really no need for any modification (Except to clip the wing of course )

Steve,
Check my build thread out for my 1/4 C/W Cub, [link=http://www.rcuniverse.com/forum/m_2708451/mpage_1/key_Sig%2Cscale%2CClipped%2Cwing%2Ccub/tm.htm]C/W Cub[/link]
I made several mods, changed the struts,Robart gear and added a functional door. The plane is covered with Sig Koverall and is painted with latex paint. Still looks good after 5 years of flying.
Anthony

WacoNut,
I have looked at your thread and there is a lot of good inforamtion in it. I'm doing the metal struts from cubmans site and I will be using Koverall and latex paint. Did you use flat hingers like the plans show for the ailerons or robart?

I two was not comfortable with the dowel rod connected elevators. I used a dowel pushrod and two 4-40 pushrods to control the elevator halves. Once the set up is made it is pretty fool proof and I have used this method many times before.

Steve,
I used Robart hinges.
Anthony

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My cub is the two piece full wing version and I noticed at the rear of the right haft there is no mechanical connection to the center section. When I pull the wing forward it moves away at the back. Has anyone else seen this? I know when the plane is flying there will be pressure pushing on the wing but sometimes there could be negative pressure put on the wing. I will post some pictures later.

CK1...

I'm in the process of building my "first" 1/4 scale cub and am still trying to decide which engine to use. Since you've done several, could you tell us which engines you've used and which of those provided the best performance for this airframe?

Rick...

I'm at exactly the same spot on my build and noticed the same thing. I am building a small "box" that fits snugly around that aft spar that will include a blind nut on the top to accept a bolt to be installed in a recess in the bottom of the wing.

Rick...

Hi- the Cub frame-up looks very nice! If you wish to obtain the neat fabric fairing near the fin- stab junction consider making the stab in 2 separate halves. You can make them plug into the fuse and the rigging of the stab-fin-fuse will be functional. Cover the fuse with the fin in situ. Use fairing over the hole where the stab plugs in just like on fullscale. Make it from cardstock, styrene sheet or lithoplate. I can send pics of this if interested. Cubs are fun! I've built 3 with 2 more on the way!

Rick , The best performance in my opinion was with the Saito 150 , superb power and not as thristy as the Saito 180 . The OS 120 flew it very well but I pefered the added power of the 150 . I did build one with a G38 at request of the owner and he quickly decided he wanted it changed after the first few flights (way too much weight). I pulled the G38 off and put an OS 120 back on it for him . I have flown one on a 91fs and was not happy with the power . A cub needs to fly light (like a cub) adding a gas engine adds a lot of extra weight (engine , batteries , etc) and the end result is usualy a plane that looks like a cub but doesnt fly much like one . I hope this helps in your decision of an engine .

smkrcflyer , I know exactly what you are refering to . The wing joining can easily be modified by building in a joining tab that will keep the trailing edges from sliding apart .
This can be as simple as adding a small false spar that protrudes from the center section root rib that will fit into a pocket that you would build into the mating root rib on the right wing panel , The false spar can be secured permanantly to the center section and when the wings are slid together a screw would hold the false spar into the mating socket on the right wing panel . It is not as complicated as it may sound even if youve already covered the wing . The modification can be done on the underside of the wing were patching the covering wont be noticed .