Balancing a Biplane
10-04-2010, 03:36 PM
#1
Thread Starter
Join Date: Aug 2010
Location: Bolingbrook, IL
Posts: 161
Likes: 0
Received 0 Likes
on
0 Posts
Balancing a Biplane
<span style="font-size: small">I have a Sig Hog Bipe and OF COURSE I want to make sure it's balanced properly. I have a Great Planes CG Machine, but there is no way to balance the hog with this tool unless you turn the plane upside down on the balancer. And that just doesn't work. Does anyone have a suggestion on how to use the GP Balancer to balance a biplane? If not, guess I have to go back to the two finger method.
Thanks in advance!! </span>
Thanks in advance!! </span>
10-04-2010, 03:53 PM
#2
RE: Balancing a Biplane
It may just be the wrong tool for the job.[
]
The plane should be supported under the upper wing for balance, but the rods of the CG machine will hit the lower wing, I believe.
Check this thread out:
http://www.rcuniverse.com/forum/m_70..._1/key_/tm.htm
]The plane should be supported under the upper wing for balance, but the rods of the CG machine will hit the lower wing, I believe.
Check this thread out:
http://www.rcuniverse.com/forum/m_70..._1/key_/tm.htm
10-04-2010, 05:08 PM
#3
Senior Member
Join Date: Apr 2007
Location: Port MacquarieNew South Wales, AUSTRALIA
Posts: 521
Likes: 0
Received 1 Like
on
1 Post
RE: Balancing a Biplane
Hi,
I use one of these to balance all my models. Twenty minutes work to make the device and your good to go. Works fine on bipes, pattern and 3D models. I leave mine permantly set up in the rafters of my shed.
http://home.mindspring.com/~the-plum...%20Machine.htm
Cheers,
Colin
I use one of these to balance all my models. Twenty minutes work to make the device and your good to go. Works fine on bipes, pattern and 3D models. I leave mine permantly set up in the rafters of my shed.
http://home.mindspring.com/~the-plum...%20Machine.htm
Cheers,
Colin
10-05-2010, 10:57 AM
#6
Senior Member
Join Date: Apr 2007
Location: Woodville, WI
Posts: 1,159
Likes: 0
Received 0 Likes
on
0 Posts
RE: Balancing a Biplane
I built one of these balancers.
I found you can get a "false positive" with it. How? Friction. There is friction everywhere.
1. On the pivoting dowel (wood-on-wood) on the top.
2. Where the string wraps around the dowel.
3. Where the string holds the wings.
I found I could have the plane be "level" and the friction could hold it there. But it wasn't balanced.
Maybe false positive is the wrong term. Maybe a better term would be "easily fooled into thinking the plane is balanced."
Sadly, you need the friction to operate this. Without friction, an out of balance plane would spin/slide, and your plane would be tail (or nose) down in an instant.
For example, if a plane is tail heavy, the friction could hold it level, and at best the plane would shift forward a little. The plump-bob might be behind your balance point, but it might only be a very little bit. You might be fooled into thinking, "That's pretty close. Close enough."
When I tried it on my Hog Bipe, I found I had to manipulate too many things simultaneously to use it effectively. I like to be able to set it on a balancer, no matter how out of balance, and not worry about the plane "getting away from me". I can move/tweak it a little without worry something would slip.
Your mileage may vary. Good luck.
I found you can get a "false positive" with it. How? Friction. There is friction everywhere.
1. On the pivoting dowel (wood-on-wood) on the top.
2. Where the string wraps around the dowel.
3. Where the string holds the wings.
I found I could have the plane be "level" and the friction could hold it there. But it wasn't balanced.
Maybe false positive is the wrong term. Maybe a better term would be "easily fooled into thinking the plane is balanced."
Sadly, you need the friction to operate this. Without friction, an out of balance plane would spin/slide, and your plane would be tail (or nose) down in an instant.
For example, if a plane is tail heavy, the friction could hold it level, and at best the plane would shift forward a little. The plump-bob might be behind your balance point, but it might only be a very little bit. You might be fooled into thinking, "That's pretty close. Close enough."
When I tried it on my Hog Bipe, I found I had to manipulate too many things simultaneously to use it effectively. I like to be able to set it on a balancer, no matter how out of balance, and not worry about the plane "getting away from me". I can move/tweak it a little without worry something would slip.
Your mileage may vary. Good luck.
10-05-2010, 02:54 PM
#7
Senior Member
Join Date: Apr 2007
Location: Port MacquarieNew South Wales, AUSTRALIA
Posts: 521
Likes: 0
Received 1 Like
on
1 Post
RE: Balancing a Biplane
Hi vmsguy,
Not sure where your problem with friction arises as the entire assembly is or should be "free swinging". Certainly friction is required to hold the model level in the rig at the points you describe but the entire rig swings, unless you are using very heavy or stiff cord to suspend the rig the plumb bob must point to the CofG assuming both the rig and the plumb bob are free to swing?
You most certainly can have the model level and unbalanced but the plumb bob will point to the incorrect CofG. Add, remove or reposition weight until the level model has the plumb bob point to the correct GofG.
Cheers,
Colin
Not sure where your problem with friction arises as the entire assembly is or should be "free swinging". Certainly friction is required to hold the model level in the rig at the points you describe but the entire rig swings, unless you are using very heavy or stiff cord to suspend the rig the plumb bob must point to the CofG assuming both the rig and the plumb bob are free to swing?
You most certainly can have the model level and unbalanced but the plumb bob will point to the incorrect CofG. Add, remove or reposition weight until the level model has the plumb bob point to the correct GofG.
Cheers,
Colin
10-05-2010, 09:31 PM
#8
Senior Member
RE: Balancing a Biplane
Like this...
Old PSS sloper, c.g. long ago determined.
Set up in the sling with the pointer, the pointer showed that was the proper point with the equipment in the proper places in the plane.
Without knowing where the c.g. should be though, all the pointer shows is where the c.g. is at the time of the test.
Old PSS sloper, c.g. long ago determined.
Set up in the sling with the pointer, the pointer showed that was the proper point with the equipment in the proper places in the plane.
Without knowing where the c.g. should be though, all the pointer shows is where the c.g. is at the time of the test.
10-06-2010, 01:58 AM
#9
Senior Member
Join Date: Dec 2008
Location: Cape L\'\'\'\'\'\'\'\'Agulhas, SOUTH AFRICA
Posts: 687
Likes: 0
Received 2 Likes
on
2 Posts
RE: Balancing a Biplane
See pic - DARN, no wonder I cannot get the plane to balance.... I need to plant another tree at the tail....
Humor aside, I had alwaysa problem determining the correct CG for my rc planes, butwhen I read about this balancing tool, I had an "Eureka" moment - it is almost elegantly simple and effective.
Thanks to the inventor.
Bundu
Humor aside, I had alwaysa problem determining the correct CG for my rc planes, butwhen I read about this balancing tool, I had an "Eureka" moment - it is almost elegantly simple and effective.
Thanks to the inventor.
Bundu
10-06-2010, 08:02 AM
#10
My Feedback: (17)
Join Date: Nov 2002
Location: Goodyear, AZ
Posts: 1,427
Likes: 0
Received 0 Likes
on
0 Posts
RE: Balancing a Biplane
This a picture of how I balance a biplane. Two pieces of wood, say 1x2 screwed together around the upper wing with an eyelet back the correct distant from the leading edge of the upper wing. Use the front screw against the leading edge of the wing for the reference point. Hang the plane and adjust you gear to get the balance where it should be. (The piece of light plywood in the picture is unrelated to the balancing of the plane.)
Chuck
Chuck
10-06-2010, 12:35 PM
#11
Senior Member
Join Date: Apr 2007
Location: Woodville, WI
Posts: 1,159
Likes: 0
Received 0 Likes
on
0 Posts
RE: Balancing a Biplane
ORIGINAL: Crash Campbell
Hi vmsguy,
Not sure where your problem with friction arises as the entire assembly is or should be ''free swinging''. Certainly friction is required to hold the model level in the rig at the points you describe but the entire rig swings, unless you are using very heavy or stiff cord to suspend the rig the plumb bob must point to the CofG assuming both the rig and the plumb bob are free to swing?
You most certainly can have the model level and unbalanced but the plumb bob will point to the incorrect CofG. Add, remove or reposition weight until the level model has the plumb bob point to the correct GofG.
Cheers,
Colin
Hi vmsguy,
Not sure where your problem with friction arises as the entire assembly is or should be ''free swinging''. Certainly friction is required to hold the model level in the rig at the points you describe but the entire rig swings, unless you are using very heavy or stiff cord to suspend the rig the plumb bob must point to the CofG assuming both the rig and the plumb bob are free to swing?
You most certainly can have the model level and unbalanced but the plumb bob will point to the incorrect CofG. Add, remove or reposition weight until the level model has the plumb bob point to the correct GofG.
Cheers,
Colin
I didn't write my previous post very well. That's my bad.
The "cradle" or "swing" style balancer can and does work. I conceed that as well.
And yes I know that the whole rig is free swinging/moving.
But I changed also changed my "false positive" to "easily mislead into thinking the plane is balanced"
As you said, it's posible for the rig to hold the plane level, even though it's out of balance. That's were the possibility of "misleading" the builder comes in.
Traditional "stand" type balancers, because they pivot on the desired balance point, "Level" and "Balanced" are the same thing.
But with this "cradle" style, "level" is not necesarily "balanced." It might be, but it also might NOT be. And that's the rub.
The builder, so used to equating "level" and "balanced" upon seeing the plane held level, the builder may think "Hey, it's balanced! WooHoo!" And if the builder isn't carefully watching the plumb-bob, they could have an unbalanced plane.
Personally, my biggest reason for abandoning its use was convenience, having a plane hang from the ceiling, getting all the string set up, moving the plumb-bob to proper height. Having the plane sway and settle. Took time, bump it, and another few minutes pass as the plane settles again. Shoot, the string slipped. Just was a pain in my posterior.
I ended building a simple one out of PVC pipe, and I had my bipe balanced in about 3 minutes.
10-07-2010, 04:49 PM
#12
Senior Member
Join Date: Apr 2007
Location: Port MacquarieNew South Wales, AUSTRALIA
Posts: 521
Likes: 0
Received 1 Like
on
1 Post
RE: Balancing a Biplane
ORIGINAL: vmsguy
I didn't write my previous post very well. That's my bad.
The ''cradle'' or ''swing'' style balancer can and does work. I conceed that as well.
And yes I know that the whole rig is free swinging/moving.
But I changed also changed my ''false positive'' to ''easily mislead into thinking the plane is balanced''
As you said, it's posible for the rig to hold the plane level, even though it's out of balance. That's were the possibility of ''misleading'' the builder comes in.
Traditional ''stand'' type balancers, because they pivot on the desired balance point, ''Level'' and ''Balanced'' are the same thing.
But with this ''cradle'' style, ''level'' is not necesarily ''balanced.'' It might be, but it also might NOT be. And that's the rub.
The builder, so used to equating ''level'' and ''balanced'' upon seeing the plane held level, the builder may think ''Hey, it's balanced! WooHoo!'' And if the builder isn't carefully watching the plumb-bob, they could have an unbalanced plane.
Personally, my biggest reason for abandoning its use was convenience, having a plane hang from the ceiling, getting all the string set up, moving the plumb-bob to proper height. Having the plane sway and settle. Took time, bump it, and another few minutes pass as the plane settles again. Shoot, the string slipped. Just was a pain in my posterior.
I ended building a simple one out of PVC pipe, and I had my bipe balanced in about 3 minutes.
ORIGINAL: Crash Campbell
Hi vmsguy,
Not sure where your problem with friction arises as the entire assembly is or should be ''free swinging''. Certainly friction is required to hold the model level in the rig at the points you describe but the entire rig swings, unless you are using very heavy or stiff cord to suspend the rig the plumb bob must point to the CofG assuming both the rig and the plumb bob are free to swing?
You most certainly can have the model level and unbalanced but the plumb bob will point to the incorrect CofG. Add, remove or reposition weight until the level model has the plumb bob point to the correct GofG.
Cheers,
Colin
Hi vmsguy,
Not sure where your problem with friction arises as the entire assembly is or should be ''free swinging''. Certainly friction is required to hold the model level in the rig at the points you describe but the entire rig swings, unless you are using very heavy or stiff cord to suspend the rig the plumb bob must point to the CofG assuming both the rig and the plumb bob are free to swing?
You most certainly can have the model level and unbalanced but the plumb bob will point to the incorrect CofG. Add, remove or reposition weight until the level model has the plumb bob point to the correct GofG.
Cheers,
Colin
I didn't write my previous post very well. That's my bad.
The ''cradle'' or ''swing'' style balancer can and does work. I conceed that as well.
And yes I know that the whole rig is free swinging/moving.
But I changed also changed my ''false positive'' to ''easily mislead into thinking the plane is balanced''
As you said, it's posible for the rig to hold the plane level, even though it's out of balance. That's were the possibility of ''misleading'' the builder comes in.
Traditional ''stand'' type balancers, because they pivot on the desired balance point, ''Level'' and ''Balanced'' are the same thing.
But with this ''cradle'' style, ''level'' is not necesarily ''balanced.'' It might be, but it also might NOT be. And that's the rub.
The builder, so used to equating ''level'' and ''balanced'' upon seeing the plane held level, the builder may think ''Hey, it's balanced! WooHoo!'' And if the builder isn't carefully watching the plumb-bob, they could have an unbalanced plane.
Personally, my biggest reason for abandoning its use was convenience, having a plane hang from the ceiling, getting all the string set up, moving the plumb-bob to proper height. Having the plane sway and settle. Took time, bump it, and another few minutes pass as the plane settles again. Shoot, the string slipped. Just was a pain in my posterior.
I ended building a simple one out of PVC pipe, and I had my bipe balanced in about 3 minutes.
All becomes clear now. I guess I'm lucky as I have plenty of height in my shed to allow the Vanessa to be permanently set up. You are dead right level doesen't equate to balanced unless the bob points to the desired CofG. On a slightly differrent topic I rebuilt a Thunder Tiger Imagine 50 that a mate crashed on it's maiden apeared very tail heavy. He is an engineer (always goes by the book) and a very competent pattern flyer, he assembled it with the CofG exactly as the instructions advised. When I replaced the firewall and rebuilt the front of the fuselage I ran the dimensions through my Cof G calculator. It came out 50mm or two inches in front of the position advised in the instructions and now flys like a dream. I guess the message is if it doesn't "look right" don't fly until you check and re-check.
Cheers,
Colin
10-10-2010, 09:35 PM
#14
Senior Member
Join Date: Apr 2007
Location: Port MacquarieNew South Wales, AUSTRALIA
Posts: 521
Likes: 0
Received 1 Like
on
1 Post
RE: Balancing a Biplane
Hi valkeriy,
I guess it depends on what you want from the hobby and your participation. I'm sure more Moore people fly bies than you think
Cheers,
Colin
I guess it depends on what you want from the hobby and your participation. I'm sure more Moore people fly bies than you think
Cheers,
Colin
10-11-2010, 12:28 PM
#15
Senior Member
Join Date: Apr 2007
Location: Woodville, WI
Posts: 1,159
Likes: 0
Received 0 Likes
on
0 Posts
RE: Balancing a Biplane
ORIGINAL: valkeriy
LOL all of that just to balance a plane is why moore people dont buy biplanes
LOL all of that just to balance a plane is why moore people dont buy biplanes
One gets out of the sport what one puts into it.
I took my Hog Bipe to a fly-in in last spring.
There were some scale warbirds there. Some twins. And a bunch of simple sport planes. Not to mention the gaggle of Cubs.
Mine was the only biplane there. It's nothing special, just a standard ARF.
Anyway. Of the 'spectators' there. My plane got just as many, if not more, visitors and onlookers than most other planes.
Not crowing.. just saying...
