I have just finished a MW super chipmunk and the recommended CG is at 115mm on the plane I finished is at 100 to 105. Slightly nose heavy… Have a ST 90 on the front and 2 battery packs

Would I get away with this?.

I heard 3/8” (9mm) is ok each way is ˝” 12 mm pushing it?

thanks in advance for input

Yea, you'll get away with it but it could cause faster landings than it would if it were balanced correctly........Why not balance at the recommended cg?....... it's usually conservative.

nose heavy is OK! your landings are going to be a little fast. The chipmonk is not a good candidate for a tail heavy situation. If you manage to get it to recommended cg and decide to go further back then do it in very small increments. MW or WM? The World Models Chipmonk ARF is an exception to the chipmonk rule. It is an all around forgiving aircraft. Great flyer but its gonna fly like a chi[pmonk and not like an Extra!!!!

I known what you mean about the CG.. but everything is packed in so nicely.... I'll have to find a new place for the battery to secure to.

I have flaps... nose heavy hot and then hit the flaps??

and yes bit dyslexic to WM

Don't worry about it.That's such a little amount it won't make much difference at all.I have a wm super chipmunk with a os61fx and it fly's beautiful.Mines right at the recommended cg.Go fly and have fun---Mike

Remember this:

A nose heavy plane won't fly well; but a tail heavy plane won't fly at all.

CG location is very important. If you don't put it in the right spot then your flight characteristics will suffer. Aerobatic pilots know very well how important CG is. Being too tail heavy or too nose heavy will mean sloppy manuevers or worse; conditions that could lead to a spin that is un-recoverable.

While it's true that an aft CG will produce a plane that loops and snaps on a dime if you go outside the aft CG location you're just asking for trouble.

Nose heavy planes will require you to add elevator trim just to fly staight and level. You won't be able to have much use of that elevator when you need it. A plane should be properly balanced so the control surfaces aren't being over taxed and asked to do more than they need to. You'll also reduce the load on the servo and save battery power.

Bottom line: put the CG where it needs to be. A good starting point on first flights is at the forward end of the range given by the manufacturer. Depending on how the performance is and what your preferences are you can them move the CG back a bit and see how you like it. But never go outside the range listed unless you really, really know what you're doing and what the results will be.

CG and CP have an important relation ship to one another. The CP (center of pressure on the wing) needs to be behing the CG. When the CG is moved aft of the CP then you start becoming unstable. And the CP location is fixed and can't be moved. So don't ask how to change it. In order to change the CP you'd have to add wing sweep or change the airfoil section.

hth

Jeff

My experience is that the recommended CG is only an approximation and is almost always too far forward. You really need to fly the plane and decide for yourself if it's handling properly.

My opinion is that if you're within 1/2 inch, go fly the airplane. You can fine tune from there.

If you're an inexperienced pilot, it's alway safe to err on the nose heavy side. Moving the CG back to an optimum point, however, will result in the best handling airplane. That can only be accomplished by fly-and-try.

Good luck.

Its worth taking time to get the C of G right, better this than walking home with a bag of bits.
Make sure your method of balancing the model is accurate.
Finger ends under the wings is not good enough, you can easily be 10mm out.
Be accurate and mark or record the measurement.
Start off slightly nose heavy,...thats better than tail heavy. You can then adjust a bit at a time until you personally are happy with it. Dont follow someone elses advice who says " put it 20mm further back" It may be ok for them but not for you. It may take a dozen flights to get it right but who cares if it ends up right.
Last thing if you have computer radio, set the dual rates up so at least you have a chance at the flick of a switch if the Cof G is a bit out

Listen To Jbrundt.

A forward CG will cause the nose of the plane to always drop if power is not carried into the turns. It will also require that you carry more power to safely land the plane. The elevator will not be as effective as it could be in a nose heavy condition when the engine is at idle.

Since the moment arm from the tail to the nose is so great, it will take very little tail weight to balance correctly. Add some sheet lead under the tailwheel mount if you have one.

A Chipmunk can be an extremely responsive aircraft when it's set up correctly. Better to start at the correct starting CG and work your way to other CG locations. Remember, those advising you to make your first flights at a CG location other than those recommended by the manufacturer have nothing to lose. You, on the other hand, most certainly do.

Silversurfer

CG can make the difference between a good flying plane and a great flying plane. It is also a matter of how you plan to fly the plane. A 3D aerobat may need a different center than a 3 channel trainer.

For example my Aerobird, a RTF, comes perfectly balanced for a 6 cell battery. The company makes a 7 cell option available but makes no provision to move the battery back to maintain the CG.

The plane flies fine under power, but if you are gliding or just crusing at half throttle, it wants to nose down so you always have some back adjustment on the elevator. You have to work a little harder to make the plane fly smoothly.

Also, when you hand launch this electric, it drops more than you would like with the 7 cell even though the 7 cell has more power.

So, I cut the foam that sets the location of the 6 cell to move the 7 cell back 1/2 inch. Now she launches better glides better and cruises at half throttle much better.

That is what a minor move in CG does.

Hope that helps.

I thought the saying was:

A nose heavy plane flies poorly, a tail heavy plane flies once.

Fly the plane with the CG where it is. If it seems poorly responsive to the elevator, or won't slow down to land, do whatever it takes to move the CG back a bit. You are close enough that it should not be a huge problem.

Leonard

I saw a tail heavy plane fly once. Damn thing cleared out the spectators until it came down. After that, CG became more important than it had been to me.

cg on a plane is everything - for us!

we use this all the time

That graphic is great!