Variable CofG
 

Heres a tip I discovered by accident - thought I would share it with you all.

The smoke tank in my model was located in my model just in front of the CofG and I noticed that the 3d ability of that model improved as the diesel (smoke fluid) was used up - not surprising as the GofG moved backwards - but it was a PITA to land with the CofG that far back.

So - moved the smoke tank to behind the CofG and got excellent 3d but as the smoke was used up the characteristics got gradualy more tame.

Put in 2 smoke tanks - 1 in front of the CofG and one behind - for take off the front tank was filled and once airborne the smoke pump is used to pump the diesel into the aft tank giving lively performance - for landing just pump the fluid (servo switchable festo fitting) back into the forward tank - easy landings.

Also useful for finding the optimum CofG - pump fluid backwards and forwards until optimum CofG is found - land - measure the balance point - empty the fluid - use lead or reposition stuff to get that balance back then you can use your smoke pump again for its intended purpose!!!

ps - two 12oz tanks fit in nicely in a WH Ultimate plus a 24 oz petrol tank

David.

RE: Variable CofG
 

You are a very clever fellow.

The only problem with this idea is the added weight of all this stuff. Total weight will be more because of shiftable ballast, but it's a very clever idea.

TF

RE: Variable CofG
 

RC Boats have been doing something similiar to this for years. They would have a empty tank on one side of th eboat and as the race went on and the fuel was used up, a water pickup would put water into the empty tank, keeping the balance point. Of course the hard part was finding out how slow or fast the tank should fill.

Bruce

RE: Variable CofG
 

One full 24oz tank of fuel it's 1 1/2lb+ so you are flying with an extra 1 1/2lb that is not needed and I bet you it would be more fun to fly a lighter plane than a plane with smoke but 1 1/2lb+ heavier!!!
Lighter flies better and it's a lot more fun than having smoke!!!! ?I have done both and I rather not to have smoke,,, mayube on 40% with 150cc of power an extra 1lb or 2lb wouldn't be so bad!!!

But that's just me!!!

RE: Variable CofG
 

I have found that not everyone thinks lighter flies better.

Weight is definitely the enemy when doing 3d stuff, but for anything else a plane can be too light. Especially for IMAC or other precision aerobatics, some added weight makes the plane steadier and it presents better.

Also a lot of people prefer a little extra weight if it is used to make the plane stronger. It's very irritating to put all that money and effort into a new plane just to knock the gear off on the first landing and tear up the bottom of the plane.

TF

RE: Variable CofG
 

I dont care about the extra 1 and 1/2 pounds - i dont see that weel under 10% of the AUW weight makes that much difference especially with a tuned Zenoah 62 in the nose.

RE: Variable CofG
 

I think you would be pleasently surprised to lose that 1 1/2 lbs... Not to mention the weight of the G62 over say a DA 50... But to each his own.

RE: Variable CofG
 

Yeah I hear what your saying but the place I fly is just on the west coast of the UK and is prone to frequent breezes of 15 to 20 knots. I have other planes that are very lightly loaded and its a bit like flying a kite on a breezy day - I sometimes ballast lightly loaded models like my 1/3 scale Clipped wing Taylorcraft just to make it flyable!! The difference the extra pound and a half of the smoke set up makes it flyable when otherwise it would not be practical. Much better penetration and acurate tracking - the trade off is higher landing speed but with a 1 mile tarmac strip I usually manage to stop before the end of it !!!:D