If you side mount your engine in a AC do you need to balance the plane laterally? That is with the engine head hanging off to one side do you need to add weight to the opposite side wing panel. If not would you have to compensate with aileron trim?

skeeter

G'day Mate,
You should always check your lateral balance, it can make a huge difference to the way a plane flys, it doesn't matter which way your engine is mounted, check it anyway.

You should always balance laterally. I dont think it's as important as CG. Others wouldn't fly without it.
What you dont want to do is compensate with aileron trim, if you roll inverted you have magnified the problem. If you're so out of balance laterally that it effects the way it flys, weight it. Just because the engine is mounted sideways doesn't mean you have to weight it though.

Quite often when installing an engine especially a 2 stroke on its side we use a Pitts style muffler which puts the exhaust straight out the bottom,so the only extra side weight is the head of the motor.
To counter act that I normally place my flight battery on the opposite side in the fuse to the head.
Of course as you progress to better models and learn more about fine tuning the set up,you will always laterally balance your plane by first adjusting components inside the fuse and then by adding weight if you have to.
Most modelers just trim it out in flight with a bit of aileron or rudder.
Some times on my fun fly planes I balance them by the prop shaft and by the tail wheel assembly with some fishing line looped around each one.
I just add weight to the outer wing tip to get them level and even a large screw inserted into the very end of the wing will do the trick.
Have fun , hope this helps.

The first time I checked the lateral balance of a plane and saw it plunk down hard to one side, it scared me how far out it was!! It didn't take much weight near the outside edge of the wing tip to correct it but I can see that the plane could suddenly dump to the heavy side if I slowed the plane down as you would when getting ready to land!! [X(] After seeing that I take lateral balancing very seriously.

So how do you support the model to balance it laterally? String, rods underneath.

skeeter

If the plane is a trike gear, I rest the tip of the tail on the bottom of the fuselage on a pencil placed length wise to the fuselage on the freezer and lift the plane by the nose cone while hanging on to one side of the wing. Then I make sure that the plane is level and then carefully loosen my grip on the wing and see if it starts to tilt to the side or if the plane remains level. I may push the plane slightly to one side and then the other if the balance seems to be ok. If it is, it will self right itself. If the plane tilts to the side, I use some electrical tape and stick on a piece of weight beside the outside edge of the wing rib on the outside edge of the wing opposite to the tilt. Then I check the balance again and add or delete some weight until the plane balances. From experience I can usually guess how much weight to start with. When I have the weight I need, I make a slit in the covering over the wing rib and use canopy glue to glue the weight in. After the glue has cured overnight I patch the slit with a piece of covering. If the plane is a tail dragger, then the only difference is that I rest the plane on the tail wheel to check the balance. I use canopy glue instead of epoxy because it remains semi-flexible, flows around the weight easier, and won't let go. [8D]

Here is a "How To" on balancing. Scroll down to the section on "Lateral Balancing"

[link=http://www.rcuniverse.com/magazine/article_display.cfm?article_id=84]Balancing "How To"[/link]

As Illusion stated, I've found that merely moving the battery to one side and affixing it with ties/velcro/tape, etc. goes a long way to getting the latteral balance right.

Then you can use the technique of adding small wingtip weights as in Miniflyer's post, to fine tune the plane.

Often the battery alone can be enough, as you'll need to trim the plane out for torque effects anyway.

I use a little different system. I remove the prop and hook a loop in a suspended string over the prop shaft. I slip another string under the rudder hinge closest the thrustline of the engine. I do it once just before covering with all systems in place and again after covering. Note that if you haven't glued the hinges in you should masking tape the rudder to the vert. stab.

One of my favorite balancing methods is to place pennies over the aileron servo on the high wing. Then I remove the servo and tape the pennies to the servo housing with black electrical tape. Cheap and easy and you can alter it after the covering is on.

BTW, have you ever seen a side mounted engine at 3o'clock? They're all at 9o'clock, right. Ever think about it?

All our engines turn in the same direction, right. So all of them produce a reaction torque in the other direction. And hanging the engine out on the side they all hang out on, puts a tad of counterbalance against that torque.

So if you ever have a notion to mount the engine at 3o'clock, think again.

I thought it was so the muffler would stuck down and not up. You'll get your tail feathers all oily.

An alternative method is in-flight trimming. Trim for straight and level hands off then roll inverted and see if a wing drops. Add weight to the light wing and re-check. It should fly hands off both upright and inverted. The advantage is that this method can help show other issues such as a slightly twisted wing or assymetric flaps.

Either way, it's worth doing lateral balance. A plane that tracks straight through loops and rolls is lovely to fly.

Cheers from the Barfly.

On all the planes that I have put together, I place a small screw-in hook On the suggested CG point, if it is a low wing I put it on the bottom of the wing. This makes it easy to check the CG and to hang the plane from the ceiling. On all my planes I needed 10 to 20 grams of lead on the left wing .