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-   -   Balancing (https://www.rcuniverse.com/forum/kit-building-121/7651007-balancing.html)

egrave 06-23-2008 09:58 AM

Balancing
 
I just built a high winger airplane and it is taking 20oz to balance it is that to much weight

MinnFlyer 06-23-2008 10:02 AM

RE: Balancing
 
It's never too much if that's what it takes to make it balance, but double check that you are balancing it in the correct place, and see if you can shift the battery forward to avoid so much added weight.

-pkh- 06-23-2008 10:51 AM

RE: Balancing
 
Definitely try to move stuff around to help reduce the weight you have to add to balance it out. First, I try to move stuff around to balance it and keep the weight the same, then if all else fails, I try to get something useful out of any weight I have to add (larger/heavier batteries, metal gear servos, larger engine, etc.)

Here's some tricks I've used:

Tail heavy:
1) Move battery as far front as possible
2) Move engine foward on the mount
3) Move receiver/servos forward if possible
4) Install a bigger engine!

Nose heavy:
1) Move battery as far back in the tail as possible, & use larger battery if necessary
2) Install metal gear servos (heavier) if there are any mounted behind the CG
3) Move engine back on the mount (closer to the firewall)

sgillmore 06-23-2008 12:07 PM

RE: Balancing
 
Some more detail would help answer your question.

1. Which kit/plane are we talking about?
2. What's the overall weight?
3. What engine are you using?

In general, it sounds like a LOT of weight to me. Most planes are designed to come out close within a specified engine range. I know there are a lot of variables that affect this. I always strive for no dead weight, but if I have to add more than 1/2 lb (8 oz) or so to a 60 to 1.20 plane I start looking for better solutions.

vicman 06-23-2008 12:12 PM

RE: Balancing
 
20 oz[X(]
Do you have the engine mounted??

egrave 06-23-2008 03:04 PM

RE: Balancing
 
The plane I got is call a perfection the fuselage is 48" long the wing sits 7" from the fire wall the wing root is 12".I have place the battery under the fuel tank and the receiver is just under the front of the wing I use a K&B twister engine. I have 5oz mounted on the motor mount and 8oz inside the fue tank well and I still need 8 more oz on the motor mount to balance it.

vicman 06-23-2008 03:13 PM

RE: Balancing
 
Try one of those brass prop nuts. Your pretty close.

outdoorhunting 06-24-2008 07:44 AM

RE: Balancing
 
Hey, guys. I don't want to steal the other guy's thread, but I have a balance question. I know that you balance a " high wing" right side up, & a "low wing" inverted. I have a Will Hobby Pole Cat " 40 size" 50" WSP powered by Magnum XL 46. It is a "mid-wing" Do I balance it inverted or right side up ??

RCKen 06-24-2008 09:11 AM

RE: Balancing
 
One quick question before you start moving everything and adding lots of weight. Did you balance the plane with the fuel tank empty or full?? The tank should have been empty and if there was any fuel in it that could really throw your balance out of whack.

Ken

egrave 06-24-2008 09:32 AM

RE: Balancing
 
No the fuel tank is completely empty

RCKen 06-24-2008 09:39 AM

RE: Balancing
 
Ok, then I would follow the advice the others have given above. Move as much equipment as you can before you start adding weight.

Ken

RICKSTUBBZ 06-24-2008 11:12 AM

RE: Balancing
 


ORIGINAL: egrave

I just built a high winger airplane and it is taking 20oz to balance it is that to much weight
In my opinion 20oz (1 1/4) pounds is a lot of weight if you are talking about a 5 to 6lb aircraft.

I am wondering, is there anything you can do to lighten the tail. Is there excessively heavy hardware that has been added? Have the elevator or rudder servos been put in the tail? If 20 oz has to be added to the nose then maybe only 4 or so needs removed from the tail.

I would also like to add in case there are any new comers reading this. Yes, balancing is typically done with an empty tank. But an airplane should still balance properly once the fuel tank is full.

Good luck

-pkh- 06-24-2008 11:55 AM

RE: Balancing
 
I agree, see if you can reduce the weight at the very back of the plane. Remember, it's the moment of an item (weight x distance from CG) that is important, so reducing weight at the very back, or adding weight to the very front (e.g. weighted prop nut) will give you the largest CG change with a given amount of weight added/removed.

I'd definitely consider moving the engine forward in the mount, and/or install a larger engine.

carrellh 06-24-2008 12:20 PM

RE: Balancing
 

ORIGINAL: egrave
The plane I got is call a perfection the fuselage is 48" long the wing sits 7" from the fire wall the wing root is 12".I have place the battery under the fuel tank and the receiver is just under the front of the wing I use a K&B twister engine. I have 5oz mounted on the motor mount and 8oz inside the fue tank well and I still need 8 more oz on the motor mount to balance it.
If you can move the battery pack and the lead from the tank compartment to the engine compartment you might be able to lose some of the weight.

Our club had a pylon race in May. Rules were pretty loose and it was for fun only. Everyone had to use a World Models Sky Raider Mach II with a .46 or smaller bushing engine. Every person's plane was tail heavy. Several people tie-wrapped the battery pack to the engine mount, or built a battery box, and avoided adding any lead to their planes.

vicman 06-24-2008 02:19 PM

RE: Balancing
 
That's strange Carrell, of the half dozen or so SRIIs I've been around or owned none of them had balance issues that required additional weight.[X(]

GAP-RCU 06-24-2008 02:46 PM

RE: Balancing
 


ORIGINAL: outdoorhunting

Hey, guys. I don't want to steal the other guy's thread, but I have a balance question. I know that you balance a " high wing" right side up, & a "low wing" inverted. I have a Will Hobby Pole Cat " 40 size" 50" WSP powered by Magnum XL 46. It is a "mid-wing" Do I balance it inverted or right side up ??
Balance it on which ever side that's the most stable - when it's balancing on your fingers or C.G. machine, it should not want to flip over with the slightest movement.


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