Questions and Answers If you have general RC questions or answers discuss it here.

Hobbico Avistar C.G. Range...

Reply
Old 03-01-2003, 04:15 AM
  #1
ufdfireman
Thread Starter
 
Join Date: Feb 2003
Location: Fairfield, NJ
Posts: 86
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Hobbico Avistar C.G. Range...

Using the Great Planes C.G. Machine, my Avistar is balanced at 2.75 ".
Here is my problem:
The instructions that came with the plane suggest the C.G. is @ 3.25" for your "first flights".
Another place I read, it says the C.G. Range is between 2.5" & 3.5".

Should I really be concerned where my C.G. is at or should I add weight to bring it to the 3.25" mark?
ufdfireman is offline  
Reply With Quote
Old 03-01-2003, 02:12 PM
  #2
Stick Jammer
 
Join Date: Nov 2002
Location: Crete, IL
Posts: 2,251
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Hobbico Avistar C.G. Range...

Tower's specs list the CG range between 3 5/8" to 4 1/2" back from the leading edge with 3 5/8" as a docile starting point.
At 2 3/4" your a little nose heavy which will probably be OK but it might make flaring for a nice landing a little more difficult. Have you tried moving the battery a little further back?
Stick Jammer is offline  
Reply With Quote
Old 03-01-2003, 03:42 PM
  #3
ufdfireman
Thread Starter
 
Join Date: Feb 2003
Location: Fairfield, NJ
Posts: 86
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Hobbico Avistar C.G. Range...

I forgot to mention that I already moved the receiver/battery tray as far back as possible.
ufdfireman is offline  
Reply With Quote
Old 03-01-2003, 04:48 PM
  #4
bullseye000
 
Join Date: Jul 2002
Location: Batavia, IL
Posts: 284
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Hobbico Avistar C.G. Range...

I haven't checked Towers web site but I built 2 of these last summer and I saved the manuals so I dug them out and checked. The manual says "The balance point is located 3-1/4" (83mm) back from the leading edge. This is the point at which your model should balance for your first flights. Later, you may experiment by shifting the balance up to 5/16" (8mm) forward or back to change the flying characteristics". It also recommends not exceeding the stated cg range. I balanced both planes at the 3-1/4" mark and both planes flew excellent and handled perfectly. I was pretty impressed with the overall quality of the planes.
bullseye000 is offline  
Reply With Quote
Old 03-01-2003, 04:51 PM
  #5
bullseye000
 
Join Date: Jul 2002
Location: Batavia, IL
Posts: 284
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Hobbico Avistar C.G. Range...

Sorry I did forget to mention that I added about 1/4 to a 1/2oz of lead to the tail of the plane to get it to balance on the recommended cg. I cut a 1" opening in the fuse ahead of the stab, coated the weight with epoxy and glued it in. Covered te hole with a scrap of Monokote.
bullseye000 is offline  
Reply With Quote
Old 03-01-2003, 05:16 PM
  #6
ufdfireman
Thread Starter
 
Join Date: Feb 2003
Location: Fairfield, NJ
Posts: 86
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Hobbico Avistar C.G. Range...

Well I did all I could...
It's to a point where it is balanced @ 3.25" with a roll of electrical tape about 3.25" down from the back window..

Now I just need to see what that weighs!

Photo 1

Photo 2

I just don't understand....
I buy an ARF version of a plane, build it as specified in the instructions, make absolutely no alterations and yet we have to add .25 - .5 oz of weight to get it properly balanced.
Very frustrating.

EDIT: I also just emailed Hobbico with the problem... lets see what they say.
ufdfireman is offline  
Reply With Quote
Old 03-01-2003, 07:05 PM
  #7
bgi
 
Join Date: Feb 2002
Location: Duluth, GA
Posts: 907
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Hobbico Avistar C.G. Range...

What brick of an engine do you have up front to cause this?
bgi is offline  
Reply With Quote
Old 03-01-2003, 07:31 PM
  #8
ufdfireman
Thread Starter
 
Join Date: Feb 2003
Location: Fairfield, NJ
Posts: 86
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Hobbico Avistar C.G. Range...

I have what came with the kit...
an OS .40 LA.
ufdfireman is offline  
Reply With Quote
Old 03-01-2003, 08:42 PM
  #9
Stick Jammer
 
Join Date: Nov 2002
Location: Crete, IL
Posts: 2,251
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Hobbico Avistar C.G. Range...

ufdfireman,
Don't get frustrated, most ARF's end up needing a little lead here or there. A half ounce is nothing.
Stick Jammer is offline  
Reply With Quote
Old 03-01-2003, 08:43 PM
  #10
hookedonrc
 
hookedonrc's Avatar
 
Join Date: Dec 2002
Location: Tulsa, OK
Posts: 2,838
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Hobbico Avistar C.G. Range...

I had the same problem with mine. It flies great with the OS46FX that I mounted, but there is enough lead in the tail you can use it as a weapon. During training, the tail was broken off on one of my better take off's. Pulled back on the throttle when it was about 5 ft off the ground instead of the elevator, snapped the tail right off when it hit. Was able to fix it and have used it for the last year. Still have the weight though.
hookedonrc is offline  
Reply With Quote
Old 03-02-2003, 01:48 AM
  #11
bgi
 
Join Date: Feb 2002
Location: Duluth, GA
Posts: 907
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Hobbico Avistar C.G. Range...

ufdfireman,

Wierd. I guess it's part of the manufacturing irregularities. Best to get it balanced, though! Stick Jammer is right. .25 to .5 oz is nothing.

clear skies.
bgi is offline  
Reply With Quote
Old 03-02-2003, 04:33 AM
  #12
bullseye000
 
Join Date: Jul 2002
Location: Batavia, IL
Posts: 284
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Hobbico Avistar C.G. Range...

You'll never notice the weight. The farther back you can get it the less you'll need. There is a solid former in front of the stab so I put the weight in front of it.
bullseye000 is offline  
Reply With Quote
Old 03-04-2003, 01:40 AM
  #13
ufdfireman
Thread Starter
 
Join Date: Feb 2003
Location: Fairfield, NJ
Posts: 86
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Hobbico Avistar C.G. Range...

Thanks for the help everyone....

I got it all balanced now... put it inside the fuse. in front of the stab like bullseye suggested.

Now I just need to patch the hole with covering!

Thanks again
ufdfireman is offline  
Reply With Quote
Old 03-04-2003, 04:37 PM
  #14
BenWillis
 
Join Date: Dec 2002
Location: Anderson, SC
Posts: 237
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Hobbico Avistar C.G. Range...

I put one of these together for may dad las weekend and it too needed about 1/2 oz of lead in the tail to ballance. It has an ASP 46 which i am sure is a bit heavier than the reccomended 40.

Yet to see how she files due to weather

Ben in SC
BenWillis is offline  
Reply With Quote
Old 03-04-2003, 05:14 PM
  #15
MinnFlyer
 
MinnFlyer's Avatar
 
Join Date: Apr 2002
Location: Willmar, MN
Posts: 28,519
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Hobbico Avistar C.G. Range...

Don't feel bad about 1/2 oz. I just completed an ARF that needed 3/4 of a POUND for nose weight!

BTW, It flew great.
MinnFlyer is offline  
Reply With Quote
Reply


Thread Tools
Search this Thread
Display Modes

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



All times are GMT -8. The time now is 02:25 AM.