Go Back  RCU Forums > RC Airplanes > Beginners
Reload this Page >

Tiger 60 Kit Balance Point ??

Notices
Beginners Beginners in RC start here for help.

Tiger 60 Kit Balance Point ??

Old 03-22-2008, 06:27 PM
  #1  
WILDBILL M
Member
Thread Starter
 
Join Date: Aug 2007
Location: Johnstown, PA
Posts: 54
Likes: 0
Received 0 Likes on 0 Posts
Default Tiger 60 Kit Balance Point ??

Tiger 60 CG is listed at 3-3/4 to 4-3/4 back from leading edge. What is best, 3-3/4, 4-3/4, or somewhere inbetween ?? How is flight affected at 3-3/4 vs 4-3/4 ??? Why a 1" span ?? Thanks guys. Bill M.
Old 03-22-2008, 06:37 PM
  #2  
CGRetired
My Feedback: (1)
 
CGRetired's Avatar
 
Join Date: Sep 2004
Location: Galloway, NJ
Posts: 8,999
Likes: 0
Received 1 Like on 1 Post
Default RE: Tiger 60 Kit Balance Point ??

The reason there is a span of the measurement pont is because of the variations in the build (or in the case of an ARF the assembly) process. They (Goldberg) has on idea where you plan on putting your battery, nor what kind of servos you intend to use. They all weigh in at different weights and can all cause a shift in the actual CG.

Measure it using any method you wish, your fingers or with a CG device, then set it for wher the nose will slightly dip at some point within the CG limits. Then fly it. After you fly, you can then adjust the CG as necessary by shifting the battey forward or aft, or by adding weight to the nose or removing it as necessary.

In other words, there is no real way to answer your question with a definitive "4 1/2 inches" or some other measurement with accuracy. It's a range that will get you in the air successfully, then you make adjustments as you see fit after that.

Hope this helps.

CGr.
Old 03-22-2008, 06:48 PM
  #3  
WILDBILL M
Member
Thread Starter
 
Join Date: Aug 2007
Location: Johnstown, PA
Posts: 54
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Tiger 60 Kit Balance Point ??

Thanks CGr Your reply helps. Bill M.
Old 03-22-2008, 07:45 PM
  #4  
da Rock
Senior Member
 
Join Date: Oct 2005
Location: Near Pfafftown NC
Posts: 11,517
Likes: 0
Received 2 Likes on 2 Posts
Default RE: Tiger 60 Kit Balance Point ??

Why is there a CG range described?

Because they wish to provide a safe range for the CG in case different people want different pitch stability from their model. The designer or developer has found that a 3.75" CG gives the most pitch stability with sufficient elevator response to be safe. And worked out that a 4.75" CG gives the most elevator response with sufficient stability to be safe. That's what CG ranges are about.

And then the designers test the elevator throws to find out what to recommend to match that CG range.

No matter what your airplane weighs after completion, the CG range fits. CG's are actually located by the size and shape of the wing versus the size, shape and location of the tail. My arf Tiger60 came out at 7'7oz. If your build comes out at 6lb 6oz, you can adjust battery or shift stuff to get the CG at 4.75" and your Tiger will fly just as agile as mine. My CG is right at 4.75" and mine is agile. Nice and agile. And both will have perfectly sufficient stability. They will have almost identical elevator response and recover pitch the same. You won't have to shift quite as much mass fore or aft to get your CG as I might, but a CG range is easy to predict and the prediction is dead reliable to do. Just measure the wing and tail and plug the numbers into the formulas that aeronautical designers have used forever. And if you're say the designer of the Tiger, you then go out with a safe CG located for the maiden flights. And if you WERE the designer, you then test fly with different CGs to prove the pitch response and pitch stability for your instruction manual.

BTW, my Tiger60 was preceeded by a TigerII. And with both models, I knew the CG ranges suggested were probably going to be conservative coming from a reputable company like Goldberg. And I knew I just might want more effectiveness out of the elevator than the suggested most aft CG probably would give. But I wanted to be sensible, so I measured both planes to get the numbers to plug into the formulas. And nowadays we don't have to work those formulas out with paper and pencil, or even a calculator. I ran them through the geistware.com application. I know from experience that some airplanes I've flown wound up with a CG WAY back, but no farther back than 10% Static Margin. So I ran the numbers through the geistware.com app with a 10% SM. It spit out that that CG would be at 4.75" Hey, that's what the manual gives. So when I took the sucker out with that CG, I knew it wouldn't be unflyable. It would be flyable. But I also knew the elevator throws would absolutely be sufficient, and with that CG would feel QUICK. Turns out they didn't feel too quick. With that CG pitch response that was really good. And elevator throws were ok. (look at how small the elevator is). Only bad thing I discovered, was that there was little need to test different CG locations. And I love to test stuff. So I'd cut myself out of some of the most fun testing.

CG ranges are starting points for the maiden flight. Then YOU can move it to suit with complete confidence of WHERE moving it would be safe.

That's what CG ranges do for you.
Attached Thumbnails Click image for larger version

Name:	Om34145.jpg
Views:	12
Size:	180.4 KB
ID:	910784  
Old 03-22-2008, 11:22 PM
  #5  
hungryandbroke
Senior Member
 
Join Date: May 2007
Location: blacksburg, SC
Posts: 322
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Tiger 60 Kit Balance Point ??

That is a Nice Flying plane..... .60 will be enough for smoothe flying buy stick a .90 on it and you will have one aerobatical airplane that flys like its on rails!

One of the best planes Goldberg ever came up with!

It's Awesome!
Old 03-23-2008, 07:04 AM
  #6  
Sourkraut
 
Sourkraut's Avatar
 
Join Date: Oct 2006
Location: Redneckville, CANADA
Posts: 356
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Tiger 60 Kit Balance Point ??



One of the best planes Goldberg ever came up with!

It's Awesome!
[/quote]

I concur.. I'm running a Tower Hobbies .75 on mine(started off with a GMS.76 in it which got put into another plane) and she really hauls ass. I use this plane to break in all my .61-.90 motors. CG is at 4.5" and all up weight is about 8.25 lbs(needed a fair bit of nose weight) Flies awesome and the landings are solid with no bouncing at all.

Curt
Attached Thumbnails Click image for larger version

Name:	Ec88877.jpg
Views:	9
Size:	70.5 KB
ID:	911129   Click image for larger version

Name:	Om33129.jpg
Views:	10
Size:	56.6 KB
ID:	911130   Click image for larger version

Name:	Lg16743.jpg
Views:	9
Size:	62.3 KB
ID:	911131  
Old 03-23-2008, 07:45 AM
  #7  
WILDBILL M
Member
Thread Starter
 
Join Date: Aug 2007
Location: Johnstown, PA
Posts: 54
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Tiger 60 Kit Balance Point ??

daRock - Very well Explained- Thank you and all the other replies. Installing an O.S. .61 FX with 13x6 Prop. Converted to tail drager. Bill M.

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.