Go Back  RCU Forums > RC Airplanes > Kit Building
 Model weight specification >

Model weight specification

Community
Search
Notices
Kit Building If you're building a kit and have questions or want to discuss kit building post it here.

Model weight specification

Thread Tools
 
Search this Thread
 
Old 05-29-2013 | 06:05 AM
  #1  
Taxus812's Avatar
Thread Starter
Member
 
Joined: Apr 2012
Posts: 80
Likes: 0
Received 0 Likes on 0 Posts
From: windsor, CT
Default Model weight specification

<h2 style="font-size: 1.1em; color: rgb(39, 39, 39); clear: both; font-family: Arial, Helvetica, sans-serif; background-color: rgb(242, 242, 242);"></h2>is the model weight specification typicaly the weight of just the airframe or the aproximate weight of the assembled aircraft, motor and radio equipment ?


(I did see one listed as apromate flying weight so I assum that means fully built)



<br type="_moz" />
Old 05-29-2013 | 06:27 AM
  #2  
FlyerInOKC's Avatar
My Feedback: (6)
 
Joined: Nov 2004
Posts: 14,505
Received 400 Likes on 322 Posts
From: Oklahoma City, OK
Default RE: Model weight specification

It is the all up weight with the exception of fuel if a glow or gasser is used.
Old 05-29-2013 | 06:27 AM
  #3  
Banned
 
Joined: Oct 2002
Posts: 2,670
Likes: 0
Received 1 Like on 1 Post
From: San Diego, CA
Default RE: Model weight specification

Depends on how sneaky the manufacturer is. Frequently an estimate of all up, ready to fly, using standard components, Your mileage may vary. I have seen some, where the box of wood provided weighed more then the advertised all up weight. Kind of hard to get there from here.

Les
Old 05-29-2013 | 06:40 AM
  #4  
 
Joined: May 2002
Posts: 6,852
Received 33 Likes on 32 Posts
From: Mandeville, JAMAICA
Default RE: Model weight specification


ORIGINAL: LesUyeda

Depends on how sneaky the manufacturer is. Frequently an estimate of all up, ready to fly, using standard components, Your mileage may vary. I have seen some, where the box of wood provided weighed more then the advertised all up weight. Kind of hard to get there from here.

Les

Unfortunate but so true. I generally consider the weights specified as being minimum.
Old 05-29-2013 | 06:43 AM
  #5  
FlyerInOKC's Avatar
My Feedback: (6)
 
Joined: Nov 2004
Posts: 14,505
Received 400 Likes on 322 Posts
From: Oklahoma City, OK
Default RE: Model weight specification

Building techniques also affect the weight. I like to add a little modification here and there or reinforce something I don't like so I have a tendency to get a little heavier than advertised.
Old 05-29-2013 | 07:17 AM
  #6  
sensei's Avatar
 
Joined: Jul 2002
Posts: 2,829
Received 17 Likes on 15 Posts
From: SAN ANTONIO, TX
Default RE: Model weight specification

I like to leave as much in the box and on the shelves of the LHS as possible, so my stuff comes out on the light side of the kit manufacture's specifications.

Bob
Old 05-29-2013 | 07:47 AM
  #7  
FlyerInOKC's Avatar
My Feedback: (6)
 
Joined: Nov 2004
Posts: 14,505
Received 400 Likes on 322 Posts
From: Oklahoma City, OK
Default RE: Model weight specification

Show off!
Old 05-29-2013 | 07:59 AM
  #8  
Bax
My Feedback: (11)
 
Joined: Apr 2002
Posts: 19,483
Likes: 0
Received 8 Likes on 7 Posts
From: Monticello, IL
Default RE: Model weight specification

For all the kits/ARF's I'm familiar with, the weight range in the specifications is the recommended ready-to-fly weight of the model. For engine-powered models, it is without fuel, but electric models do include the battery packs.

Kits can weigh more in the box because there is a lot of extra wood that's not used (all the wood holding the die-cut pieces, and the centers of ribs and bulkheads, and sticks and sheet you'll cut down). You'll also wind up carving and sanding a lot more wood off the assembled airframe. Don't forget about the packing material that won't be used. ....And, yes, there are some kits that have such dense wood that you're not going to get the airframe anywhere close to the recommended weight range. If you can, talk to the kit maker about that.
Old 05-29-2013 | 10:38 AM
  #9  
Taxus812's Avatar
Thread Starter
Member
 
Joined: Apr 2012
Posts: 80
Likes: 0
Received 0 Likes on 0 Posts
From: windsor, CT
Default RE: Model weight specification

Im way over what they say this cub should be (http://www.hangar-9.com/Products/Def...ProdID=HAN1500).The original spec stated it would be 6 - 7 lbs flying weight (with a saito .56 FS) . I weigh in at 8.5lbs with an OS .72 FS supass II. The .72 is heavy (20oz) but not that much

I was a little worried about being so much over so I did a wing loading calculation.The wing cube loading puts me at about 9.3 (wing loading at 22oz/sq<font color="#000099" face="Arial, Helvetica, sans-serif" size="2">.ft)</font>so it should be ok.


<br type="_moz" />
Old 05-29-2013 | 12:23 PM
  #10  
My Feedback: (-1)
 
Joined: Apr 2003
Posts: 14,400
Received 9 Likes on 8 Posts
From: Hemderson, NV
Default RE: Model weight specification

Wouldn't worry about it as a cub has a bunch of lift. Being an ARF there isn't a lot you can do about it other then strip the covering and start lightening. Last one I built was the Goldberg Cub and it was heavy at 8 pounds with an OS .91fs. As a 40 size plane I thought it was heavy but the wing is built like a tank and it has a lot of ply in the build. In flight it is perfect though. The .91 was the only engine the fellow I built it for had but a nice .46 two stroke would do just as well. He added floats and figured he would need the extra power anyway, I don't think so but you use what you have.
Old 05-29-2013 | 06:55 PM
  #11  
My Feedback: (1)
 
Joined: May 2009
Posts: 1,284
Likes: 0
Received 3 Likes on 3 Posts
From: Ocala, Florida
Default RE: Model weight specification

If you have not yet C/G balanced the Cub and it is nose heavy with the four stroke .72, then move the RX and battery to the rear of the plane's cabin area to achieve C/G balance without adding any additional dead weight. Move the parts that have to be there to balance it if possible. Keep the amount of non functional added ballast to a minimum. Use a light weight spinner and a wooden prop to take a little weight off the nose if that helps. In any case at 8.5 lbs a J-3 cub of that size will fly fine. If you are putting a pilot in your plane, a J-3 Cub gets flown solo from the back seat. Enjoy...

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
Trackbacks are Off
Pingbacks are Off
Refbacks are On



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

Copyright © 2026 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.