Chipmunk C of G

I have this to maiden soon.

It's a Seagull 80" jobbie.

Now, I don't wholly trust manufacturers recommended C/Gs so I thought I'd canvass opinion here.

What other Chipmunks do you fly? And where is the C/G in percentage terms, at the root?

So that we all measure the same, please exclude any wing fairing but obviously do include the flaps.

Seagull's setting comes out at 33% which with the slight sweep forward (or less taper of the LE than the TE), means it might be a little aft?

On my Blackhorse 45cc Chippy, the cord is 420 mm and the Manual says 125mm back from leading edge,

It flys well at that setup,

It is 85” span

So I think that is about 30%,

Get the flaps mixed in with elevator trim,

Makes Chippys happier and easier to handle at full flap usage

Thanks Bert. This is 80" and the recommended position is 130mm and the cord 380. So that bears out my suspicion already.

The book says it can upto 135 from leading edge at root where the two half’s join

Hi Chris,

I have a Galaxy Models Chippy at 72" span

Chord : 350mm

CoG: 105mm - 118mm

Regards

Robert

I have flown my Seagull 80in Chippy with C of G at 130mm as per build instructions and she seems to fly well with it at this. Mine has an OS 120 upfront and with flaps fully deployed there is very little trim change.

Cheers

Peter

This works well, I've used on my Sig Zlin 526 which had a plan CG that looked odd (it was). **LINK**

My Airsail Chipmunk (apparently very close to scale as it was originally designed as an international level competition scale model) is shown at around 4.5" on a 13" root chord. The designer (Brian Borland) has stated that this C of G is conservative and can be moved backwards to suit the pilot.

I'm not sure where my C of G is now but I certainly set it to the plan position when I built it 17 years ago and it's always been a very well mannered model.  If it's any guide, spins are predictable but scale like without aileron input, the rate increasing after a couple of turns with the nose dropping. Recovery is less scale - almost instantaneous by simply centralising the controls.

Edited By Martin Harris on 10/03/2019 15:41:27