Hi,

Ive just balanced my Kyosho Spitfire 40 ARFT kit on a GP CofG gauge and ive needed to add just under 1lb (1 pound) of weight to the nose/engine area to balance this plane. Ive been told the engine im using which is a OS46LA is quite a light engine.. Ive bascially moved everything as far forward as i could to get the right CofG but it still needs all this extra weight to balance properly.

The question is does that much sound normal ??? just seems a bit excessive for me, but im only following the instructions and using a proper gauge as it states 90mm from leading wing edge and im balancing it with the plane upside down, empty of fuel. Im going to attach the lead to the motor mount with screws...... will that be ok ??

Thx for any imput into this as i plan to fly her next sunday, so i just wanted to double check

Low wing planes should be balanced upside down. (wheels in the air!)
try that, and see what is required.

Where did you place the weight? You want it to be as far forward as posible.. the more forward you put it, the less you'll require.. Add it to the front of the firewall, not under the fuel tank...

Yes, 1lb sounds a bit drastic for a 40. sized plane, but not uncommon. Well, rarely..

I have put the weight at the moment on the engine mount just under the engine, soo i cant get any further forward than that...

Will this 1lb of weight effect the flight performance much ???

WOW! 1lb for a 40 size plane is a LOT!

Anybody else have one of these? Can that be right?

DAMN, thats a lot of dead weight! Have you tried moving the battery just behind the firewall too? You can also add a spinner weight nut made for balancing. I think you can gain up to 2 oz right on the nose which would give a good moment and it can be hidden under the actual spinner. The review of the kit says "Do not use the CG or control settings in the manual; use the recommendations in the supplemental sheet instead".

Supplement Sheet ??? lol i didnt get one i was following the one in the manual !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Thx alot cappio777 for letting me know that

Ok now for the stuipid question but i can only seem to work in mm's soo can anyone tell me what these convert too as this is what is states on the site.

C-G = 3- 13/16 to 4- 3/16
Elevator = 1/2 up 9/16 down
Alierons = 5/8
Rudder = 1- 3/8

????? none of those mesurements mean anything too me ;-0 if someone can covert those to mm's for me i would be extremely grateful

They recommend 97mm from the LE. Not much difference.

Here is an online Conversion page that would do any combination of units you want. Plug in the # on top, select the units on the left then select the units you want to convert to on the right.....answers come out the bottom.

[link=http://www.onlineconversion.com/length_common.htm]Online Conversion[/link]

Thx once again but how do i type in something like 3 - 13/16 ? it only seems to round it up

If its 3 13/16" then divide 13/16=8125....that gives you a decimal number. Now place the decimal behind the 3 like this.....3.8125. Thats your decimal interpretation of english units The rest is the same.

HMMMM MATHS 101



Prboz

One inch is very close to 25.4 mm. 1/16 inch is @ 1.6 mm. The 1.5 mm balsa sheet you buy at your hobby shop is essentially 1/16 sheet here in the USA.

Jim

is it true that low wing planes should be balanced upside down, i dont think that they are because they are made to fly the right way up not upside down
But you never know, i might be wrong.

Yes, it is true....

No matter how good, bad, or indiferent the builder and pilot are, they can not escape the laws of physics.... and gravity.

It is obvious that you have never balanced a low wing plane, so I am guessing that you have a high-wing trainer. As an experiment, try to balance your high-wing trainer upside down.... and you will discover that it will never balance, even on the exact Center of Gravity. This is because the center of gravity is above the pivot of the balance system, and it will "fall off" the pivot. Balance the plane the right way up, and the CofG will be below the pivot, and your plane becomes stable even when it is not pivoted exactly accross the CofG (it will just be nose-up or nose-down).

Believe it or not, but the laws of physics apply to both high, and low wing planes.... It is really hard to balance something on top of a pivot, but much easier to suspend something from a pivot.

I am trying to think of an every-day example .... when you carry a ladder, do you go to the middle of the ladder, lift the ladder on to your shoulder so that the bottom side of the ladder is on your shoulder, or do you lift the ladder, put your arm between the rungs, and put the top side of the ladder on your shoulder? With your arm through the ladder, the CoG of the ladder is below your shoulder, and low-and-behold, the ladder can balance on it's own. Put the whol ladder on your shoulder, and the ladder will not balance at all...

gus

P.S. Of course, your post may have been a troll, and if so, it was a good one .... Then again, people from down-under may do things upside down.....

An easier experiment that will make your light bulb blink...[sm=idea.gif].... get a bucket and try to find the center of balance with your finger while upside down. Quite easy right!. Now try to do the same thing with the bucket right side up and your finger on the bottom. Not sooooooooo easy now!

Gus, I think your ladder analogy is excellent.

Keep in mind, this is a beginners forum. No need to be so harsh on us.

I gue I guess I was a bit harsh .... should I edit ... or should I apologise .... apologies it is ....

Sorry for being harsh...

gus

Actually I think both Gus's ladder and Cappio777's bucket analogies were excellent, however, an outstanding analogy is when you balance two naked wom---oooppps wrong forum! [X(]

Stefan, can you show me how to get to that forum?

[sm=eek.gif]

[sm=lol.gif]

yes gus you are right, have never balanced a low wing plane, but i was just wondering

i have another question, when it comes to balancing something like a pitts special or an ultimate bi-plane, how do you do this.

yep,
It depends on where they say the balance point is. I have a bipe that calls for a balance point 3.75" behind the leading edge of the TOP wing, so I balance it right side up, and on the bottom of the top wing. If they happened to specify a point on the bottom wing, I'd turn the plane over (upside down) and use the top of the bottom wing.
Dennis-