World Models Chipmunk

Ian,

Is it the chipmunk or super chipmunk that you are refering to?

-Reuben

Hi we have had several of the 90 size Super Chipmunk in the club and I have flown a couple of them. All have been really good sport model and seem to live up to weekly abuse well one is certainly 5 or 6 years old I should think. Buy with confidence, they are generally pretty good kits.

Linds

I decided to go for this model.

Its a very well made and complete kit.

I am putting a Saito 82 Four stroke up front.

My only concern is that it looks as if I am going to need about 1.5lb of lead in the front to get the CoG in the right place.

Is this normal?

Thanks, Ian

I don't know about the World Models one - I have the Black Horse version - and I have to say the only lead I added was a little bit (about 40g) to th tail! I have a couple of Tiger Moths as well (similar engine/cowl shape and nose length) and neither of them have required lead. So I'm a bit surprised. World models have a generally good reputation - so again its surprising to need so much lead in the nose. Are the tail servos rearward mounted? Is there anything you could move forward?

 

BEB

Ian, that sounds very odd, are you sure you have measured correctly, 1.5lb is very excessive I would have thought, I don't recall the models I flew having any requirement like that, I would double check the positon first.

Hi Ian Ive found a build blog for this W M super chipmunk on another model website

the guy used a saito 1.00 FS and only had to add 4oz to the tail maybe you need to find another heaver engine 1.5lb cant be correct ??? can it the saito 1.00 fs weighs in at about 20oz including the exhaust ,you could move the engine further out on the mounts its all about leverage and stick the rx batt in the cowl

 

cheers ........................mark

I made a slight error in this posting, as I went for the Black Horse version in the end.

I will move the battery into the cowl, but there is nothing else that I can see that will make much of a difference.

Hi Ian,

 

I take it from the engine size its the smaller Black Horse Chippy? That's the same as I have - now I'm even more puzzled!

 

I have an OS 91FS in mine. the weight of which is about 620g. You have a Saito 82 which admittedly is somewhat lighter at about 460g. So a weight difference of about 160g. I have to put 40g of weight in the tail - and you need over 600g in the nose! On the same model! It just doesn't add up!

 

I've flown mine several times - and the only complaint I have is its habit of nosing over when taxing! The tail on mine feel very light on the ground! Indeed I have set up a special extra high rate elevator setting just for taxing or I can't keep its backside down. What's more through other threads on here I know I'm not alone with this problem on this model! If you put that much weight in the nose of mine it would simply refuse to sit on its tail!

 

Something is wrong here Ian. I know the CoG is where it is but could you possibly be measuring from the wrong place, is it worth rechecking it?

 

BEB

Hi BEB,

 

I had a one of those Chipmunks until the elevator servo failed! I got it second hand and the previous owner put larger wheels on it and bent the undercarriage legs further forward. I didn't have any problems with it nosing over during my all to brief ownership. It had an OS 61 FX on it and had some lead bolted to the firewall. Can't remember how much but nowhere near 1 1/2 lb only a few ounces at most.

 

Hmm.....might have to get another one now

 

Andy

Hi TC,

 

I "fixed" mine just last weekend - well I hope its fixed I haven't been able to get out with it yet! I took the undercart off, redrilled the holes angled a bit further forward and then sleeved them with some brass tube araldited in to act as a bush/reinforcement.

 

I'll try that - if it still bounces its backside in the air I'll stick on some bigger wheels as well.

 

It flies great - really pleasant model - just a bit of a pain on the ground!

 

BEB